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BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION
Brit. J. Anaesth. (1963), 35, 358
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION BY WALTER NORMS
Department of Anaesthetics, Royal Infirmary, Glasgow, Scotland SUMMARY
Cardiac catheterization is now an accepted method of investigation in children with congenital heart disease. It enables samples of blood to be removed in rapid succession from adjacent chambers of the heart and facilitates the recording of the blood pressure at these sites. Before such readings can be compared with each other it is essential that the patient has been maintained in a steady physiological state during the entire period of the examination. To achieve this in children, subjected to a lengthy procedure in strange surroundings, without producing marked alterations in their circulation or respiration is difficult. Herein lies the challenge to anaesthetists. Many techniques have been recommended to obtain satisfactory sedation for these patients. The problems to be overcome and the merits and demerits of the commonly used techniques have been reviewed recently (Norris, 1962) and the ideal way of handling such patients has yet to be found. It is difficult to evaluate any technique unless one knows what departures from the patient's resting state it produces and whether marked fluctuations in blood pressures and blood gases take place during the period when samples and pressure readings are being taken. Only recently has such information been published in support of some of the accepted methods and frequently it relates only to the time of sampling.
Basal narcosis based on bromethol was first used by Cournand in his early cases (Baldwin, Moore and Noble, 1946) and is still a popular method of sedating children during catheterization in many centres. The purpose of this paper is to study the changes produced by such a technique and to determine whether a steady state is produced. The results are compared with those obtained in older patients in whom the examination was performed after sedation short of sleep. MATERIAL AND METHODS
The patients. A total of 122 patients were studied, 63 being examined under basal narcosis and 59 under sedation. The distribution as to sex and age is shown in table I. Each group contained most of the common congenital heart lesions and the number of cyanotic patients in each group was similar. Techniques. Basal narcosis. This was based on bromethol given rectally half an hour before the cardiac catheterization in a dose of 100-125 mg/kg. All but the smallest children were given promethazine 10-25 mg orally 3 hours previously and, after the bromethol had induced sleep, pethidine 1 mg/lb. (2.2 mg/kg) and atropine 0.4-0.6 mg were injected intramuscularly. 358
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Basal narcosis based on bromethol was administered to sixty-three patients undergoing cardiac catheterization. The resultant changes in their circulation and respiration were similar to those found during normal sleep. Fluctuations in arterial oxygen saturation and systemic blood pressure during the catheterization were usually associated with restlessness or the intravenous administration of supplementary drugs. A further fiftynine cases were studied after sedation short of sleep. The results were variable, but when good sedation was achieved, the respiratory and circulatory changes were similar to those occurring after basal narcosis. In a disturbingly large number of patients, however, the signs of anxiety persisted throughout the catheterization and a steady state was not achieved.
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION TABLE I
The sex and age of the 122 patients and the technique adopted for cardiac catheterization. Basal narcosis
Sedation
Female Male
32 31
27 32
Age
<5 5-10 11-16 16-20 >20
14 38 8 2 1
0 2 13 21 23
Total
63
59
Sedation. The patients were sedated as follows: pentobarbitone 200-300 mg 15 cases amylobarbitone 200-300 mg 23 cases papaveretum 20 mg/hyoscine 0.4 mg 17 cases meprobamate 400-800 mg 4 cases Methods of Assessment. Given adequate time, assistance and equipment, there are many ways in which the state of respiration and circulation can be assessed. While most of these may be used during a cardiac catheterization, few can be applied to conscious children without upsetting the resting state. For the purposes of this study simple, painless tests were chosen. Respiration. Respiratory depression may be measured as a diminution of tidal and minute volumes or as an alteration in blood gas values. A reduction in ventilation is almost inevitable after basal narcosis as it accompanies normal sleep (Kleitman, 1929), but as oxygen consumption and carbon dioxide production correspondingly fall (Robin et al., 1958) it is not necessarily accompanied by any significant alteration in the oxygen or carbon dioxide content of the arterial blood and may indeed be beneficial during cardiac catheterization (Norris, 1962). We are, however, much concerned with blood p s changes, particularly changes in oxygen saturation and these have been measured. The arterial oxygen saturation can be easily measured with good relative accuracy by means of an ear oximeter. In this study a Stanco oximeter has been used and readings have been taken in
the ward, with the patient at rest, and repeatedly during the performance of the cardiac catheterization, in particular as each blood sample was removed. The patients are not disturbed by the earpiece either before or during the procedure, and even the small changes in arterial oxygen saturation caused by breath holding can be detected. The absolute accuracy of the instrument in our hands was similar to that reported by Mcllroy (1960). The arterial carbon dioxide tension was not measured in the resting state as it was not considered that the methods available at the time of this investigation could be applied to small children, without respiratory upset. However, the arterial sample obtained during the catheterization to estimate cardiac output was analyzed and the carbon dioxide tension thus obtained compared with normal Astrup standards (35-45 mm Hg). Circulation. Again simple painless tests are essential if they are to be carried out both before and during the cardiac catheterization. The arterial blood pressure was estimated by sphygmomanometer following the recommendations of Bordley et al. (1951), who, with Bergen et al. (1954), found good relative accuracy with this method. Repeated readings were taken before the procedure in the ward with the patient at rest in bed and a resting level thus obtained. Readings were again taken repeatedly during the catheterization and in particular when readings were being taken of intracardiac pressures. The heart rate was monitored before and during the procedure also, using either a pulse monitor or simple palpation. Miscellaneous. In some of the patients the radiation exposure at the patient's chin was measured to assess the risk to the anaesthetist's hand. All patients were in addition carefully observed and those examined, sedated but conscious, were questioned as to the presence of pain or unpleasant sensations. RESULTS
The results fall into two groups. In the first the readings taken at the time of the surgical cutdown and those when the catheter entered the patient's heart are compared separately with the
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Sex
359
360
BRITISH JOURNAL OF ANAESTHESIA TABLE II II TABLE
Changes in arterial oxygen saturation from resting state to (1) time of cut-down, (2) catheter entering heart. Percentage of patients Changes in oxygen saturation (per cent) Rise
>3 1-2 1-2 >3
Mean change Standard deviation Cases falling within ± 2 % of resting values
precatheterization levels and the degree of respiratory and circulatory depression estimated. In the second group the readings taken during the entire procedure and during the more limited sampling period are examined and, from the maximum and minimum readings obtained, the magnitude of the changes taking place during these times determined. Respiratory depression. The changes in arterial oxygen saturation from the resting state are shown in table II. It can be seen that the changes in arterial oxygen saturation following basal narcosis are minimal. In fact almost 85 per cent of all patients show an arterial saturation within ± 2 per cent of their resting values. The arterial carbon dioxide tensions measured as described are shown in table III. While significantly more patients have a Pac02 over 40 mm Hg after basal narcosis, the difference in the mean readings (2.1 mm Hg) is less than occurs during normal sleep (3.5 mm Hg) (Robin et al., 1958). III
Arterial carbon dioxide tension during cardiac catheterization. Percentage of patients Arterial Pco2 (mm Hg) 30-39 40-49 50 and over Mean tension (mm Hg) Standard deviation
Basal narcosis
Sedation
23 59 18
50 28 22
44-5
±6-42
42-4
±10-2
(1)
(2)
(1)
(2)
9 17 38 28 8
10 12 40 34 4
2 11 49 25 13
2 11 36 38 13
—0-62 ±3-74
—008
—0-59 ±1-35
—0-79
85
85
83
±2-24 86
±1-8
Circulatory changes. The changes in the systemic blood pressure after each of the techniques is shown in table IV. The mean fall in blood pressure after basal narcosis is greater than after sedation (P<0.01). At first this would seem to favour the use of sedation but this is not so. Much of the difference is explained by the fact that a much greater proportion of patients have a raised blood pressure after sedation (42 per cent against 4 per cent; P<0.01), showing that anxiety persists even up to the time of sampling. On examining the proportions of patients who show a similar change in blood pressure to that accompanying normal sleep, a fall in the systolic reading not exceeding 25 mm Hg, it is seen that a greater proportion show this change after basal narcosis (87 per cent against 51 per cent; P<0.01). More marked hypotension occurs with equal frequency in each series and is associated with cases showing a reduction in cardiac output as in aortic stenosis. The differences in results between the series were statistically significant both at the time of the cut-down and after the catheter had entered the heart. The changes in heart rate are shown in table V. It is interesting to note that although atropine was only administered in the series of cases with basal narcosis there is no significant difference between the two series. Variations in the steady state during catheterization. (1) Arterial oxygen saturation. The fluctuations
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No change FaU
TABLE
Sedation
Basal narcosis
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION
361
TABLE IV
Blood pressure changes from resting state to (1) cut-down, (2) catheter entering the heart. Percentage of patients Systolic pressure (mm Hg)
Basal narcosis
Sedation
(2)
(1)
(2)
4 18 69 9
2 12 77 9
42 24 27 7
37 12 42 9
Mean change (mm Hg) Standard deviation
—11-5 ± 9-3
—13-5 ± 9-9
Diastolic pressure (mm Hg)
— 1
±21-8
Basal narcosis
— 4-5
±20-5
Sedation
(1)
(2)
0)
(2)
Rise in pressure (S>5) No change Fall in pressure (<25) Fall in pressure (> 25)
5 20 70 5
7 15 73 5
25 30 40 5
23 30 45 2
Mean change (mm Hg) Standard deviation
— 8-5 ± 9-8
—10
— 3
— 3
±10-6
±13-2
±12-3
TABLE V
Changes in heart rate from resting state to (1) cut-down, (2) catheter entering heart. Percentage of patients Basal narcosis
Sedation
Change in heart rate (beats/min)
(1)
(2)
(1)
(2)
Fall No change or rise <20 Rise > 20
10 54 36
10 63 27
20 49 31
20 54 26
+ 15-5 ±14-3
+ 13-6 ±14-6
+ 15 ±19-9
+ 12-6 ±17-7
Mean change Standard deviation
in the arterial oxygen saturation during (1) the entire procedure and (2) the more limited period of sampling are shown in table VI. The only significant difference is in the wider scatter of readings after basal narcosis at the time of cutdown. When only the sampling period is considered there is nothing to choose between the methods. (2) Systemic blood pressure. The blood pressure fluctuations are summarized in table VII. During the entire period of the examination the mean fluctuation in blood pressure levels, systolic and diastolic, is less after basal narcosis (P<0.01).
After sedation the proportion of patients whose systolic pressure varies less than 10 mm Hg is smaller and the variability of the results is greater (P<0.05). Most of the fluctuations take place at the time of cut-down and, when the sampling period alone is considered, only the variability after sedation remains significantly greater. (3) Heart rate. The changes during the procedure are summarized in table VIII. It can be seen that the results produced by the two methods are almost identical.
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(1)
Rise in pressure (>5) No change Fall in pressure (<525) Fall in pressure (> 25)
BRITISH JOURNAL OF ANAESTHESIA
362 TABLE VI
Variations in arterial oxygen saturation (1) during entire catheterization, (2) during sampling time. Percentage of patients Variation in oxygen saturation (per cent) 0-2 3-5 >6
(1)
(2)
(1)
(2)
64 24 12
80 16 4
65 27 8
70 22 8
2-6 ±3
1-5 ±1-82
1-4
20 ±2-2
±2
TABLE VII
Variations in blood pressure (1) during entire procedure, (2) during sampling period. Percentage of patients Variation (mm Hg) Systolic 0-10 11-20 >20 Mean variation (mm Hg) Standard deviation Diastolic 0-10 11-20 >20 Mean variation (mm Hg) Standard deviation
Sedation
Basal narcosis (1)
(2)
(1)
(2)
66 22 12
86 12 2
40 31 29
75 12 13
11 ±7-94
6 ±6-58
18-5 ±13-9
8 ±10-8
80 11 9
93 7 0
65 23 12
80 14 6
7 ±7-35
3-2 5-34
11-7 ±9-38
7 8-44
TABLE VIII
Fluctuations in heart rate (1) during the entire procedure, (2) during sampling. Percentage of patients Basal narcosis Fluctuations (beats/min) 0-10 11-20 21-30 >30 Mean variation Standard deviation
Sedation
(1)
(2)
(1)
(2)
36 43 12 9
64 24 5 7
32 44 17 7
65 25 8 2
17 ±11 -8
10-5 ±10-7
15-5 ±10
9-5 ±8-9
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Mean variation Standard deviation
Sedation
Basal narcosis
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION
DISCUSSION
The cases studied under basal narcosis in most instances showed no greater interference with respiration or circulation than must be expected from the fact that they were examined asleep. Some of those who were desaturated, due to right-toleft shunts, were found to have a raised arterial oxygen saturation, due no doubt to the reduced oxygen demand after basal narcosis, as has previously been reported by Harmel and Lamont (1946), Smith (1950), Adelman et al. (1952) and Fieldman et al. (1955). It should be noted that in these patients a slight hypotension usually accompanied the rise in oxygen level. One child with Fallot's Tetralogy showed a rise in saturation from
80 to 89 per cent despite a fall in blood pressure from 100/60 mm Hg to 85/60 mm Hg while a child with Eisenmenger's syndrome showed a rise in saturation from 85 to 90 per cent despite a fall in blood pressure from 105/70 mm Hg to 85/60 mm Hg. This underlines the fact that mild hypotension in such cases does not necessarily cause an increase in the right-to-left shunt, as is sometimes claimed. It is equally true that raising the systemic pressure with vasoconstrictor drugs does not increase the arterial oxygen saturation of patients with Fallot's tetralogy (Burchell and Wood, 1949; Wood, 1956, 1958). A fall in arterial oxygen saturation of more than 2 per cent at the beginning of the catheterization was found in less than 10 per cent of cases and was due either to inadequate sedation and restlessness or to the use of intravenous thiopentone to supplement inadequate sedation. Hypotension greater than 25 mm Hg again occurred in less than 10 per cent of patients and was found in cases with restricted cardiac output, irrespective of the drugs used or the dosage employed. During cardiac catheterization some fluctuations in blood pressure and arterial oxygen saturation may result from other than anaesthetic causes (such as obstruction of a stenosed pulmonary artery by the catheter) and a fall of nearly 20 per cent was noted on such an occasion. Similar changes may follow the onset of supraventricular tachycardia. These changes have been excluded from consideration here as they are independent of the sedative method employed. Fluctuations in blood pressure and arterial oxygen saturation during basal narcosis arise from two causes, restlessness (fig. 1) and the use of intravenous thiopentone even in dilute solution (1£ per cent) (fig. 2) and, since so much depends on these two factors, they are considered in detail. Restlessness may be due to inadequate sedation arising from reduction in the dose of basal narcotic below 120-125 mg/kg, voiding of the enema, or drug resistance in cyanotic patients (Lucas, 1958). This latter resulted in three cyanosed patients arriving in the X-ray department awake after the full regime described earlier. It may also follow painful stimuli during the examination, as basal narcosis, while providing a state of sleep, does not abolish the reflex responses even to the pains reported by the conscious patients.
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Pain during cardiac catheterization. Cardiac catheterization is generally considered to be a painless procedure. In so far as pain comparable to that experienced during even minor surgery is concerned, this may be true. Nevertheless, during this study, when the anaesthetist was free to observe the sedated patients closely, it was noted that pain or discomfort occurred at times in twenty-seven out of fifty-nine cases. It was of such severity in seven cases that the patients wept openly for a time. Pain occurred in the arm either as the catheter was manipulated or as the local anaesthetic wore off, in the chest associated with bursts of arrhythmias, or in the shoulder or abdomen as the catheter was advanced. Discomfort was also experienced on those occasions when a stenosed pulmonary valve was obstructed by the catheter. Radiation hazards. Using a Stephen quartz fibre dosimeter an attempt was made to assess the total dose of radiation delivered at the patient's chin—the dose to which the anaesthetist's hand would be subjected. With the examination carried out at about 85 kV and 0.75 mA, the radiation at the chin measured 10-15 mR/min. This is greater than the exposure noted by Norton and Kubota (1960). Supplementary drugs. Dilute thiopentone was administered only when the narcosis with bromethol was considered inadequate at any time during the procedure. It was required more often when doses of bromethol less than 120 mg/kg were used than after the full dose (120-125 mg/kg) was given (70 per cent against 18 per cent; P<0.01).
363
BRITISH JOURNAL OF ANAESTHESIA
364
v
no
A
o •
100 V L
V
B.P. mmHg ,, O, sat. % Heart rate
v
8O
-u
JTO6O 6O
90
I2O
MIN
N
RESTLESS'
FIG. 1 Child aged 6; v.s.d. with pulmonary hypertension. Basal narcosis with bromethol (100 mg/kg). Note fall in oxygen saturation with rise in blood pressure while restless.
J6OJ8O
THIOPENTONE
110v
IOO-
A
o •
90
B.P. mmHg ,, „ O2 sat. % Heart rate
o
£ 7O 6O 5O
AT REST
o
3O
6O
9O
I2O
MIN
FIG. 2 Child aged 6; a.s.d. with pulmonary hypertension. Basal narcosis with bromethol but some was voided and child arrived awake at X-ray department. Note falls in oxygen saturation after thiopentone (1.25 per cent).
Pain arising from injection of local anaesthetic into the arm is transient and the child may be gently restrained while the drug is taking effect. In cyanosed patients it is wiser to give nitrous oxide and oxygen while the injection is made as even slight struggling may increase the cyanosis. Pain arising from passage of the catheter into abnormal sites, such as the abdomen, responds to withdrawal of the catheter and discomfort associaated with bursts of extra systoles can be similarly relieved. The high incidence of pain in the arm after an hour, as the local anaesthetic effect wears off, is considered of great importance, as it is often at this time that patients under basal narcosis
become restless. Routine re-infiltration of the wound after an hour reduces the need for supplementary intravenous thiopentone. Intravenous thiopentone still remains the standby of most anaesthetists when the level of basal narcosis is inadequate. It is indicated when the patient does not settle initially, even when undisturbed, when the examination is prolonged, or the patient moves in the absence of obvious stimuli. Despite the use of small doses of H per cent solution the drug causes falls in arterial oxygen saturation of up to 5 per cent for several minutes and a suitable period must be allowed for the oximeter reading to return to normal. On
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3O
R&T ° .
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION
(P<0.01). These findings suggest that changes in shunts are probably taking place in a considerable number of patients examined after sedation although the alteration is not sufficient to reverse the shunt and cause desaturation in non-cyanosed patients. The value of estimating shunt flow under such circumstances must, however, be questionable. Twelve patients were catheterized twice. The results of such a small series do not allow of more than tentative conclusions but the patients examined after basal narcosis showed the same response to the drugs on each occasion; those examined after sedation showed changes which depended on the degree of sedation produced; and when sedation was effective the changes closely resembled those, following basal narcosis. When both techniques were employed in the same patient basal narcosis produced sleep and steady readings, sedation, no depression but an uneven state. The circumstances of this investigation are such that any bias would have been in favour of the sedated cases as they were older and therefore more suitable for this technique. In addition some of the older patients, considered unsuited to sedation, were catheterized under basal narcosis. Despite this the results tend to favour basal narcosis but before embarking on this technique one must be prepared to supervise the children before, during and after the examination. The only anxiety caused by basal narcosis in over six years experience of this technique arose in one of the children in this group. After the enema had been given he was left unsupervised for a few minutes, due to a misunderstanding, and developed a mild respiratory obstruction and a severe tachycardia. The obstruction was quickly relieved and oxygen was given but the arterial oxygen saturation did not return to normal until the tachycardia resolved, which it did but slowly. The catheterization was cancelled but the child showed signs of cerebral irritation for a few days before making a complete recovery. How much this incident was due to mismanagement and how much to the tachycardia is difficult to assess. The child had been examined using the same technique a year before without causing undue anxiety and was subject to cyanotic attacks producing unconsciousness on the least excitement. Similar attacks
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two occasions, when cyanosis developed in cases with Fallot's Tetralogy during catheterization due either to restlessness or infundibular spasm (Wood, 1956, 1958; Lucas, 1958), small doses of thiopentone restored the oxygen saturation to normal within a very short time. Sedation short of sleep, by means of the doses of barbiturates or opiate described, produced some very surprising results. Thus while the methods used produced changes in oxygen saturation and carbon dioxide tension almost indistinguishable from those after basal narcosis, the frequent persistence of a raised blood pressure, even as the catheter entered the heart, suggests that anxiety remained in over a third of the cases examined and that the sedation had failed to produce the desired resting state. Although the rise in pressure is noted as "greater than 5 mm Hg", after sedation, all but two cases showed a rise in pressure of more than 10 mm Hg and three were in excess of 30 mm Hg. The changes in heart rate also suggest that anxiety persisted, as tachycardia was as common after sedation as after the basal narcotic combination which contained atropine. Quite marked variations in blood pressure took place during the examination when sedation was employed. Significantly more patients showed blood pressure variations of 20 mm Hg or more than after basal narcosis, even during the sampling period, and some of the fluctuations during cutdown were of the order of 50 mm Hg. The results which could follow these changes in cyanosed children are alarming. Obviously the effects of cardiorespiratory depression and fluctuations in the steady state will be most apparent in patients with right-to-left shunts. The present series included eight cyanosed children given bromethol and of these, five showed a rise in arterial oxygen saturation (1-8 per cent), one showed no change and two a fall (2 per cent, 3 per cent). After sedation two cases showed a rise in saturation (2 per cent, 3 per cent), two showed no change, and two falls of 1 per cent and 5 per cent. Under basal narcosis only two cases varied more than 5 per cent during the entire procedure and only one during sampling. After sedation four out of the six cases varied more than 5 per cent, even during sampling. The differences in these proportions are statistically significant
365
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BRITISH JOURNAL OF ANAESTHESIA
CONCLUSIONS
Basal narcosis using bromethol still provides satisfactory conditions for cardiac catheterization if adequate supervision is available. It is suggested that the initial dose of bromethol should seldom be reduced below 120-125 mg/kg as this lessens the chance of restlessness occurring and reduces the need for supplementary thiopentone. Careful attention to the known causes of pain and discomfort during the investigation will also reduce the need for intravenous anaesthesia. Although patients examined awake but apparently sedated require less supervision during and after the catheterization it appears that many remain anxious and a steady resting state is not in fact achieved. ACKNOWLEDGMENT
The patients examined were under the care of Dr. J. H. Wright, cardiologist to Glasgow Royal Infirmary, and to him and to the late Dr. G. J. Aitken and to Dr. R. M. Thomson I am grateful for their fullest co-operation during these studies. REFERENCES
Adelman, M. H., Rosenthal, A. I., Jacobson, E., and Millis, A. (1952). Anesthetic management in cardiac catheterisation. N.Y. St. J. Med., 52, 1866. Baldwin, E. de V. F., Moore, L. V., and Noble, R. B. (1946). Demonstration of ventricular septal defect by means of right heart catheterisation. Amer. Heart /., 32, 152. Bergen, F. H. van, Weatherhead, S., Treloar A. E., Dobkin, A. B., and Buckley, J. J. (1954). Comparison of indirect and direct methods of measuring arterial blood pressure. Circulation, 10, 481.
Boeson, I., Lind, J., Merrild Hansen, B., Rosendal, T., Storm, O., and Wegelius, C. (1956). The diagnosis of congenital heart disease in infants by catheterisation and selective angiocardiography. Brit. Heart J., 18, 355. Bordley, J., Connor, C. A. R., Hamilton, W. F., Kerr, W. J., and Wiggers, C. J. (1951). Recommendations for the determination of human blood pressure recording by sphygmomanometer. Circulation, 4, 503. Burchell, H. B., Helmholtz, H. F., and Wood, E. H. (1953). Overall experiences with cardiac catheterisation. Proc. Mayo Clin., 28, 50. Wood, E. H. (1949). Reproducibility of values for oxygen saturation of arterial blood in patients with congenital heart disease. /. appl. Physiol., 1, 560. Fieldman, E. J., Lundy, J. S., DuShane, J. W., and Wood, E. H. (1955). Anesthesia for children undergoing diagnostic cardiac catheterisation. Anesthesiology, 16, 868. Harmel, M. H., and Lamont, A. (1946). Anesthesia in surgical treatment of congenital pulmonary stenosis. Anesthesiology. 7, 477. Kepes, E. R., Livingstone, M., and Escher, D. J. W. (1955). Management of children during cardiac catheterisation with inhalation anesthesia. Curr. Res. Anesth. Analg., 34, 299. Kleitman, N. (1929). Sleep. Physiol. Rev., 9, 624. Lucas, B. G. B. (1958). Anoxic states and their management, in Modern Trends in Anaesthesia (eds. Evans, F. T., and Gray, T. C), p. 290. London: Butterworth. Mcllroy, M. B. (1959). The clinical use of oximetry. Brit. Heart j . , 21, 293. Norris, W. (1962). Cardiac catheterization and the anaesthetist. Brit. J. Anaesth., 34, 269. Norton, M. L., and Kubota, Y. (1960). Experiences with cardiac catheterisation using halothane compressed air anesthesia. Anesthesiology, 21, 374. Robin, E. D., Whaley, R. D., Crump, C. H., and Travis, D. M. (1958). Alveolar gas tensions, pulmonary ventilation and blood pH during physiologic sleep in normal subjects. /. clin. Invest., 37, 981. Schnabel, T. G. (1954). Cardiac catheterisation in heart disease. Med. Clin. N. Amer., 38, 16H. Smith, J. A. (1950). Anaesthesia for cardiac catheterisation. Brit. med. J., 1, 705. Wood, P. (1956). Pulmonary circulation and respiratory function. University of St. Andrews, p. 10. (1958). Symposium on congenital heart disease. Brit. Heart ]., 20, 282. L'ANESTHfiSIE DE BASE OU LES SEDATIVES EMPLOYES POUR LE CATH£T£RISME CARDIAQUE SOMMAIRE
Une anesthe'sie de base au brome'thol a 6t6 faite k 63 patients avant catheterisation intra-cardiale. Les modifications circulates et respiratoires e'taient analogues a celles trouvees pendant le sommeil normal. Les fluctuations dans la saturation arterielle en oxygene et dans la tension arterielle pendant la catheterisation etaient en general associees a de 1' agitation ou a 1'administration i.v. de medicaments complementaires. D'autres 59 cas furent etudtes apres sedation proche
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are also known to follow supraventricular tachycardia in such patients during cardiac catheterization without anaesthesia (Schnabel, 1954). It is always tempting, like Kepes et al. (1955), to attribute such troubles to the basal narcosis if this has been given and certainly in this case the respiratory obstruction was an aggravating factor, if not the cause of the trouble. It is well to remember that mishaps, and indeed deaths, have occurred during cardiac catheterization under many different sedative mixtures and that patients with such gross congenital lesions sometimes die suddenly while awaiting the investigation (Burchell et al., 1953; Boeson et al., 1956). This patient however, serves as a reminder of the heavy price to be paid for even the slightest slip in an exacting technique.
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION de l'e'tat de sommeil. Les resultats variaient, mais lorsque la sedation obtenue etait bonne, les modifications respiratoires et circulatoires etaient similaires a celles survenant apres une anesthesie de base. Chez un nombre de patients dont le nombre inquietait par son ampleur, les signes d'anxiet6 persisterent pendant toute la cathe'terisation et il fut impossible d'obtenir un 6tat de calme. BASISNARKOSE ODER SEDIERUNG FUER HERZKATHETERISIERUNG ZUSAMMENFASSUNG
sich einstellenden Veranderungen in bezug auf Kreislauf und Atmung waren ahnlich wie beim normalen Schlaf. Schwankungen im Sauerstoffgehalt des arteriellen Blutes und Schwankungen des Blutdruckes im grofien Kreislauf traten gewohnlich bei Unruhezustanden oder nach intravenoser Verabfolgung von zusatzlichen Medikamenten auf. Weitere 59 Patienten wurden nach Sedierung bei Schlaflosigkeit beobachtet. Die Ergebnisse waren unterschiedlich, aber bei guter Sedierung fanden sich Veranderungen der Atmung und des Kreislaufes ahnlich denen, wie sie bei der Basisnarkose auftraten. Bei einer unangenehmen grofien Anzahl von Patienten blieben jedoch wahrend der Herzkathederisierung die Erregungszeichen bestehen, ein ausgeglichener Zustand wurde nicht erreicht.
BOOK REVIEW The Regulation of Human Respiration (Proceedings of the J. S. Haldane Centenary Symposium). Edited by D. J. C. Cunningham and B. B. Lloyd. Published by Blackwell Scientific Publications, Oxford. Pp. 591. Price 905. Physiologists from all over the world recently gathered in Oxford to celebrate the centenary of Haldane's birth and to acknowledge his great contribution to the modern understanding of respiration. The proceedings of the symposium are now published in this book which opens with a series of eight tributes from experts in the various fields to which Haldane devoted his life. The first tribute is the original obituary notice written in 1936 for the Royal Society by Professor Douglas. This should be read by every initiate to the study of respiration, for here he will learn the origin of so great a part of the knowledge upon which his own work will be founded. Other contributions in this section include a characteristically lucid account of pulmonary gas exchange by J. H. Comroe and a discussion of Haldane's controversial views on the relation between quantum mechanics and biology by his son, Professor J. B. S. Haldane. Haldane's activity covered so wide a scope that it has not been possible even in this substantial volume to do more than deal with a small part of it. Indeed, the symposium was largely devoted to one aspect of Haldane's interest, the regulation of respiration. This subject is discussed in five of the seven sections of the book, each consisting of original contributions from a number of physiologists active in the field of respiration. The five sections include the peripheral receptors and effectors, the central receptors, the response to carbon dioxide, adaptation to high altitudes and the hyperpnoea of exercise. Each group of papers is followed by a free and lively discussion which is a most valuable feature of the book, but those readers who lack either time or special experience will regret that only a few of the papers and none of the
discussions are concluded by any form of summary. The book concludes with a few short communications relating to other subjects in which Haldane was interested, but inevitably there are many gaps and the publishers' claim that the book "is an authoritative summary of present-day knowledge of respiratory physiology" is not substantiated. Modern knowledge of the distribution of blood and the uptake of gases in the lung derived from such methods as mass spectrometry, carbon monoxide diffusion and radio-isotope techniques would surely have fascinated Haldane, but receive very little attention. Haldane was also concerned with the application of physiological methods to the elucidation of disease in man. Full justice is done to his interest in the disorders of high altitudes and great depths, but there is very little about the physiological investigation of such lung disease as silicosis to which Haldane devoted so much attention. There is not even a reference to some of the measurements of lung function most commonly used in clinical practice today (e.g. the forced expiratory volume, and the peak expiratory flow rate) nor indeed does the spirometer itself merit a place in the index. These criticisms of omission are, however, unfair to the editors who made no such claim as their publishers. They entitled their work The Regulation of Human Respiration and offered it as a tribute to J. S. Haldane. On both these counts the book is a triumph. There is surely no more comprehensive account of the control of respiration nor a more worthy memorial to a great man. The book should be available to every anaesthetist if for no better reason than to correct the impression given by one of the speakers in the symposium. This distinguished physiologist suggested that anaesthetists were suitably unbiased subjects for respiratory experiments because they "did not know much about the control of breathing". Colin Ogilvie
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An 63 Patienten wurde ftir die Herzkathederisierung eine Basisnarkose mit Bromethol verabfolgt. Die
367
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION BY WALTER NORMS
Department of Anaesthetics, Royal Infirmary, Glasgow, Scotland SUMMARY
Cardiac catheterization is now an accepted method of investigation in children with congenital heart disease. It enables samples of blood to be removed in rapid succession from adjacent chambers of the heart and facilitates the recording of the blood pressure at these sites. Before such readings can be compared with each other it is essential that the patient has been maintained in a steady physiological state during the entire period of the examination. To achieve this in children, subjected to a lengthy procedure in strange surroundings, without producing marked alterations in their circulation or respiration is difficult. Herein lies the challenge to anaesthetists. Many techniques have been recommended to obtain satisfactory sedation for these patients. The problems to be overcome and the merits and demerits of the commonly used techniques have been reviewed recently (Norris, 1962) and the ideal way of handling such patients has yet to be found. It is difficult to evaluate any technique unless one knows what departures from the patient's resting state it produces and whether marked fluctuations in blood pressures and blood gases take place during the period when samples and pressure readings are being taken. Only recently has such information been published in support of some of the accepted methods and frequently it relates only to the time of sampling.
Basal narcosis based on bromethol was first used by Cournand in his early cases (Baldwin, Moore and Noble, 1946) and is still a popular method of sedating children during catheterization in many centres. The purpose of this paper is to study the changes produced by such a technique and to determine whether a steady state is produced. The results are compared with those obtained in older patients in whom the examination was performed after sedation short of sleep. MATERIAL AND METHODS
The patients. A total of 122 patients were studied, 63 being examined under basal narcosis and 59 under sedation. The distribution as to sex and age is shown in table I. Each group contained most of the common congenital heart lesions and the number of cyanotic patients in each group was similar. Techniques. Basal narcosis. This was based on bromethol given rectally half an hour before the cardiac catheterization in a dose of 100-125 mg/kg. All but the smallest children were given promethazine 10-25 mg orally 3 hours previously and, after the bromethol had induced sleep, pethidine 1 mg/lb. (2.2 mg/kg) and atropine 0.4-0.6 mg were injected intramuscularly. 358
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Basal narcosis based on bromethol was administered to sixty-three patients undergoing cardiac catheterization. The resultant changes in their circulation and respiration were similar to those found during normal sleep. Fluctuations in arterial oxygen saturation and systemic blood pressure during the catheterization were usually associated with restlessness or the intravenous administration of supplementary drugs. A further fiftynine cases were studied after sedation short of sleep. The results were variable, but when good sedation was achieved, the respiratory and circulatory changes were similar to those occurring after basal narcosis. In a disturbingly large number of patients, however, the signs of anxiety persisted throughout the catheterization and a steady state was not achieved.
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION TABLE I
The sex and age of the 122 patients and the technique adopted for cardiac catheterization. Basal narcosis
Sedation
Female Male
32 31
27 32
Age
<5 5-10 11-16 16-20 >20
14 38 8 2 1
0 2 13 21 23
Total
63
59
Sedation. The patients were sedated as follows: pentobarbitone 200-300 mg 15 cases amylobarbitone 200-300 mg 23 cases papaveretum 20 mg/hyoscine 0.4 mg 17 cases meprobamate 400-800 mg 4 cases Methods of Assessment. Given adequate time, assistance and equipment, there are many ways in which the state of respiration and circulation can be assessed. While most of these may be used during a cardiac catheterization, few can be applied to conscious children without upsetting the resting state. For the purposes of this study simple, painless tests were chosen. Respiration. Respiratory depression may be measured as a diminution of tidal and minute volumes or as an alteration in blood gas values. A reduction in ventilation is almost inevitable after basal narcosis as it accompanies normal sleep (Kleitman, 1929), but as oxygen consumption and carbon dioxide production correspondingly fall (Robin et al., 1958) it is not necessarily accompanied by any significant alteration in the oxygen or carbon dioxide content of the arterial blood and may indeed be beneficial during cardiac catheterization (Norris, 1962). We are, however, much concerned with blood p s changes, particularly changes in oxygen saturation and these have been measured. The arterial oxygen saturation can be easily measured with good relative accuracy by means of an ear oximeter. In this study a Stanco oximeter has been used and readings have been taken in
the ward, with the patient at rest, and repeatedly during the performance of the cardiac catheterization, in particular as each blood sample was removed. The patients are not disturbed by the earpiece either before or during the procedure, and even the small changes in arterial oxygen saturation caused by breath holding can be detected. The absolute accuracy of the instrument in our hands was similar to that reported by Mcllroy (1960). The arterial carbon dioxide tension was not measured in the resting state as it was not considered that the methods available at the time of this investigation could be applied to small children, without respiratory upset. However, the arterial sample obtained during the catheterization to estimate cardiac output was analyzed and the carbon dioxide tension thus obtained compared with normal Astrup standards (35-45 mm Hg). Circulation. Again simple painless tests are essential if they are to be carried out both before and during the cardiac catheterization. The arterial blood pressure was estimated by sphygmomanometer following the recommendations of Bordley et al. (1951), who, with Bergen et al. (1954), found good relative accuracy with this method. Repeated readings were taken before the procedure in the ward with the patient at rest in bed and a resting level thus obtained. Readings were again taken repeatedly during the catheterization and in particular when readings were being taken of intracardiac pressures. The heart rate was monitored before and during the procedure also, using either a pulse monitor or simple palpation. Miscellaneous. In some of the patients the radiation exposure at the patient's chin was measured to assess the risk to the anaesthetist's hand. All patients were in addition carefully observed and those examined, sedated but conscious, were questioned as to the presence of pain or unpleasant sensations. RESULTS
The results fall into two groups. In the first the readings taken at the time of the surgical cutdown and those when the catheter entered the patient's heart are compared separately with the
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Sex
359
360
BRITISH JOURNAL OF ANAESTHESIA TABLE II II TABLE
Changes in arterial oxygen saturation from resting state to (1) time of cut-down, (2) catheter entering heart. Percentage of patients Changes in oxygen saturation (per cent) Rise
>3 1-2 1-2 >3
Mean change Standard deviation Cases falling within ± 2 % of resting values
precatheterization levels and the degree of respiratory and circulatory depression estimated. In the second group the readings taken during the entire procedure and during the more limited sampling period are examined and, from the maximum and minimum readings obtained, the magnitude of the changes taking place during these times determined. Respiratory depression. The changes in arterial oxygen saturation from the resting state are shown in table II. It can be seen that the changes in arterial oxygen saturation following basal narcosis are minimal. In fact almost 85 per cent of all patients show an arterial saturation within ± 2 per cent of their resting values. The arterial carbon dioxide tensions measured as described are shown in table III. While significantly more patients have a Pac02 over 40 mm Hg after basal narcosis, the difference in the mean readings (2.1 mm Hg) is less than occurs during normal sleep (3.5 mm Hg) (Robin et al., 1958). III
Arterial carbon dioxide tension during cardiac catheterization. Percentage of patients Arterial Pco2 (mm Hg) 30-39 40-49 50 and over Mean tension (mm Hg) Standard deviation
Basal narcosis
Sedation
23 59 18
50 28 22
44-5
±6-42
42-4
±10-2
(1)
(2)
(1)
(2)
9 17 38 28 8
10 12 40 34 4
2 11 49 25 13
2 11 36 38 13
—0-62 ±3-74
—008
—0-59 ±1-35
—0-79
85
85
83
±2-24 86
±1-8
Circulatory changes. The changes in the systemic blood pressure after each of the techniques is shown in table IV. The mean fall in blood pressure after basal narcosis is greater than after sedation (P<0.01). At first this would seem to favour the use of sedation but this is not so. Much of the difference is explained by the fact that a much greater proportion of patients have a raised blood pressure after sedation (42 per cent against 4 per cent; P<0.01), showing that anxiety persists even up to the time of sampling. On examining the proportions of patients who show a similar change in blood pressure to that accompanying normal sleep, a fall in the systolic reading not exceeding 25 mm Hg, it is seen that a greater proportion show this change after basal narcosis (87 per cent against 51 per cent; P<0.01). More marked hypotension occurs with equal frequency in each series and is associated with cases showing a reduction in cardiac output as in aortic stenosis. The differences in results between the series were statistically significant both at the time of the cut-down and after the catheter had entered the heart. The changes in heart rate are shown in table V. It is interesting to note that although atropine was only administered in the series of cases with basal narcosis there is no significant difference between the two series. Variations in the steady state during catheterization. (1) Arterial oxygen saturation. The fluctuations
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No change FaU
TABLE
Sedation
Basal narcosis
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION
361
TABLE IV
Blood pressure changes from resting state to (1) cut-down, (2) catheter entering the heart. Percentage of patients Systolic pressure (mm Hg)
Basal narcosis
Sedation
(2)
(1)
(2)
4 18 69 9
2 12 77 9
42 24 27 7
37 12 42 9
Mean change (mm Hg) Standard deviation
—11-5 ± 9-3
—13-5 ± 9-9
Diastolic pressure (mm Hg)
— 1
±21-8
Basal narcosis
— 4-5
±20-5
Sedation
(1)
(2)
0)
(2)
Rise in pressure (S>5) No change Fall in pressure (<25) Fall in pressure (> 25)
5 20 70 5
7 15 73 5
25 30 40 5
23 30 45 2
Mean change (mm Hg) Standard deviation
— 8-5 ± 9-8
—10
— 3
— 3
±10-6
±13-2
±12-3
TABLE V
Changes in heart rate from resting state to (1) cut-down, (2) catheter entering heart. Percentage of patients Basal narcosis
Sedation
Change in heart rate (beats/min)
(1)
(2)
(1)
(2)
Fall No change or rise <20 Rise > 20
10 54 36
10 63 27
20 49 31
20 54 26
+ 15-5 ±14-3
+ 13-6 ±14-6
+ 15 ±19-9
+ 12-6 ±17-7
Mean change Standard deviation
in the arterial oxygen saturation during (1) the entire procedure and (2) the more limited period of sampling are shown in table VI. The only significant difference is in the wider scatter of readings after basal narcosis at the time of cutdown. When only the sampling period is considered there is nothing to choose between the methods. (2) Systemic blood pressure. The blood pressure fluctuations are summarized in table VII. During the entire period of the examination the mean fluctuation in blood pressure levels, systolic and diastolic, is less after basal narcosis (P<0.01).
After sedation the proportion of patients whose systolic pressure varies less than 10 mm Hg is smaller and the variability of the results is greater (P<0.05). Most of the fluctuations take place at the time of cut-down and, when the sampling period alone is considered, only the variability after sedation remains significantly greater. (3) Heart rate. The changes during the procedure are summarized in table VIII. It can be seen that the results produced by the two methods are almost identical.
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(1)
Rise in pressure (>5) No change Fall in pressure (<525) Fall in pressure (> 25)
BRITISH JOURNAL OF ANAESTHESIA
362 TABLE VI
Variations in arterial oxygen saturation (1) during entire catheterization, (2) during sampling time. Percentage of patients Variation in oxygen saturation (per cent) 0-2 3-5 >6
(1)
(2)
(1)
(2)
64 24 12
80 16 4
65 27 8
70 22 8
2-6 ±3
1-5 ±1-82
1-4
20 ±2-2
±2
TABLE VII
Variations in blood pressure (1) during entire procedure, (2) during sampling period. Percentage of patients Variation (mm Hg) Systolic 0-10 11-20 >20 Mean variation (mm Hg) Standard deviation Diastolic 0-10 11-20 >20 Mean variation (mm Hg) Standard deviation
Sedation
Basal narcosis (1)
(2)
(1)
(2)
66 22 12
86 12 2
40 31 29
75 12 13
11 ±7-94
6 ±6-58
18-5 ±13-9
8 ±10-8
80 11 9
93 7 0
65 23 12
80 14 6
7 ±7-35
3-2 5-34
11-7 ±9-38
7 8-44
TABLE VIII
Fluctuations in heart rate (1) during the entire procedure, (2) during sampling. Percentage of patients Basal narcosis Fluctuations (beats/min) 0-10 11-20 21-30 >30 Mean variation Standard deviation
Sedation
(1)
(2)
(1)
(2)
36 43 12 9
64 24 5 7
32 44 17 7
65 25 8 2
17 ±11 -8
10-5 ±10-7
15-5 ±10
9-5 ±8-9
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Mean variation Standard deviation
Sedation
Basal narcosis
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION
DISCUSSION
The cases studied under basal narcosis in most instances showed no greater interference with respiration or circulation than must be expected from the fact that they were examined asleep. Some of those who were desaturated, due to right-toleft shunts, were found to have a raised arterial oxygen saturation, due no doubt to the reduced oxygen demand after basal narcosis, as has previously been reported by Harmel and Lamont (1946), Smith (1950), Adelman et al. (1952) and Fieldman et al. (1955). It should be noted that in these patients a slight hypotension usually accompanied the rise in oxygen level. One child with Fallot's Tetralogy showed a rise in saturation from
80 to 89 per cent despite a fall in blood pressure from 100/60 mm Hg to 85/60 mm Hg while a child with Eisenmenger's syndrome showed a rise in saturation from 85 to 90 per cent despite a fall in blood pressure from 105/70 mm Hg to 85/60 mm Hg. This underlines the fact that mild hypotension in such cases does not necessarily cause an increase in the right-to-left shunt, as is sometimes claimed. It is equally true that raising the systemic pressure with vasoconstrictor drugs does not increase the arterial oxygen saturation of patients with Fallot's tetralogy (Burchell and Wood, 1949; Wood, 1956, 1958). A fall in arterial oxygen saturation of more than 2 per cent at the beginning of the catheterization was found in less than 10 per cent of cases and was due either to inadequate sedation and restlessness or to the use of intravenous thiopentone to supplement inadequate sedation. Hypotension greater than 25 mm Hg again occurred in less than 10 per cent of patients and was found in cases with restricted cardiac output, irrespective of the drugs used or the dosage employed. During cardiac catheterization some fluctuations in blood pressure and arterial oxygen saturation may result from other than anaesthetic causes (such as obstruction of a stenosed pulmonary artery by the catheter) and a fall of nearly 20 per cent was noted on such an occasion. Similar changes may follow the onset of supraventricular tachycardia. These changes have been excluded from consideration here as they are independent of the sedative method employed. Fluctuations in blood pressure and arterial oxygen saturation during basal narcosis arise from two causes, restlessness (fig. 1) and the use of intravenous thiopentone even in dilute solution (1£ per cent) (fig. 2) and, since so much depends on these two factors, they are considered in detail. Restlessness may be due to inadequate sedation arising from reduction in the dose of basal narcotic below 120-125 mg/kg, voiding of the enema, or drug resistance in cyanotic patients (Lucas, 1958). This latter resulted in three cyanosed patients arriving in the X-ray department awake after the full regime described earlier. It may also follow painful stimuli during the examination, as basal narcosis, while providing a state of sleep, does not abolish the reflex responses even to the pains reported by the conscious patients.
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Pain during cardiac catheterization. Cardiac catheterization is generally considered to be a painless procedure. In so far as pain comparable to that experienced during even minor surgery is concerned, this may be true. Nevertheless, during this study, when the anaesthetist was free to observe the sedated patients closely, it was noted that pain or discomfort occurred at times in twenty-seven out of fifty-nine cases. It was of such severity in seven cases that the patients wept openly for a time. Pain occurred in the arm either as the catheter was manipulated or as the local anaesthetic wore off, in the chest associated with bursts of arrhythmias, or in the shoulder or abdomen as the catheter was advanced. Discomfort was also experienced on those occasions when a stenosed pulmonary valve was obstructed by the catheter. Radiation hazards. Using a Stephen quartz fibre dosimeter an attempt was made to assess the total dose of radiation delivered at the patient's chin—the dose to which the anaesthetist's hand would be subjected. With the examination carried out at about 85 kV and 0.75 mA, the radiation at the chin measured 10-15 mR/min. This is greater than the exposure noted by Norton and Kubota (1960). Supplementary drugs. Dilute thiopentone was administered only when the narcosis with bromethol was considered inadequate at any time during the procedure. It was required more often when doses of bromethol less than 120 mg/kg were used than after the full dose (120-125 mg/kg) was given (70 per cent against 18 per cent; P<0.01).
363
BRITISH JOURNAL OF ANAESTHESIA
364
v
no
A
o •
100 V L
V
B.P. mmHg ,, O, sat. % Heart rate
v
8O
-u
JTO6O 6O
90
I2O
MIN
N
RESTLESS'
FIG. 1 Child aged 6; v.s.d. with pulmonary hypertension. Basal narcosis with bromethol (100 mg/kg). Note fall in oxygen saturation with rise in blood pressure while restless.
J6OJ8O
THIOPENTONE
110v
IOO-
A
o •
90
B.P. mmHg ,, „ O2 sat. % Heart rate
o
£ 7O 6O 5O
AT REST
o
3O
6O
9O
I2O
MIN
FIG. 2 Child aged 6; a.s.d. with pulmonary hypertension. Basal narcosis with bromethol but some was voided and child arrived awake at X-ray department. Note falls in oxygen saturation after thiopentone (1.25 per cent).
Pain arising from injection of local anaesthetic into the arm is transient and the child may be gently restrained while the drug is taking effect. In cyanosed patients it is wiser to give nitrous oxide and oxygen while the injection is made as even slight struggling may increase the cyanosis. Pain arising from passage of the catheter into abnormal sites, such as the abdomen, responds to withdrawal of the catheter and discomfort associaated with bursts of extra systoles can be similarly relieved. The high incidence of pain in the arm after an hour, as the local anaesthetic effect wears off, is considered of great importance, as it is often at this time that patients under basal narcosis
become restless. Routine re-infiltration of the wound after an hour reduces the need for supplementary intravenous thiopentone. Intravenous thiopentone still remains the standby of most anaesthetists when the level of basal narcosis is inadequate. It is indicated when the patient does not settle initially, even when undisturbed, when the examination is prolonged, or the patient moves in the absence of obvious stimuli. Despite the use of small doses of H per cent solution the drug causes falls in arterial oxygen saturation of up to 5 per cent for several minutes and a suitable period must be allowed for the oximeter reading to return to normal. On
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3O
R&T ° .
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION
(P<0.01). These findings suggest that changes in shunts are probably taking place in a considerable number of patients examined after sedation although the alteration is not sufficient to reverse the shunt and cause desaturation in non-cyanosed patients. The value of estimating shunt flow under such circumstances must, however, be questionable. Twelve patients were catheterized twice. The results of such a small series do not allow of more than tentative conclusions but the patients examined after basal narcosis showed the same response to the drugs on each occasion; those examined after sedation showed changes which depended on the degree of sedation produced; and when sedation was effective the changes closely resembled those, following basal narcosis. When both techniques were employed in the same patient basal narcosis produced sleep and steady readings, sedation, no depression but an uneven state. The circumstances of this investigation are such that any bias would have been in favour of the sedated cases as they were older and therefore more suitable for this technique. In addition some of the older patients, considered unsuited to sedation, were catheterized under basal narcosis. Despite this the results tend to favour basal narcosis but before embarking on this technique one must be prepared to supervise the children before, during and after the examination. The only anxiety caused by basal narcosis in over six years experience of this technique arose in one of the children in this group. After the enema had been given he was left unsupervised for a few minutes, due to a misunderstanding, and developed a mild respiratory obstruction and a severe tachycardia. The obstruction was quickly relieved and oxygen was given but the arterial oxygen saturation did not return to normal until the tachycardia resolved, which it did but slowly. The catheterization was cancelled but the child showed signs of cerebral irritation for a few days before making a complete recovery. How much this incident was due to mismanagement and how much to the tachycardia is difficult to assess. The child had been examined using the same technique a year before without causing undue anxiety and was subject to cyanotic attacks producing unconsciousness on the least excitement. Similar attacks
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two occasions, when cyanosis developed in cases with Fallot's Tetralogy during catheterization due either to restlessness or infundibular spasm (Wood, 1956, 1958; Lucas, 1958), small doses of thiopentone restored the oxygen saturation to normal within a very short time. Sedation short of sleep, by means of the doses of barbiturates or opiate described, produced some very surprising results. Thus while the methods used produced changes in oxygen saturation and carbon dioxide tension almost indistinguishable from those after basal narcosis, the frequent persistence of a raised blood pressure, even as the catheter entered the heart, suggests that anxiety remained in over a third of the cases examined and that the sedation had failed to produce the desired resting state. Although the rise in pressure is noted as "greater than 5 mm Hg", after sedation, all but two cases showed a rise in pressure of more than 10 mm Hg and three were in excess of 30 mm Hg. The changes in heart rate also suggest that anxiety persisted, as tachycardia was as common after sedation as after the basal narcotic combination which contained atropine. Quite marked variations in blood pressure took place during the examination when sedation was employed. Significantly more patients showed blood pressure variations of 20 mm Hg or more than after basal narcosis, even during the sampling period, and some of the fluctuations during cutdown were of the order of 50 mm Hg. The results which could follow these changes in cyanosed children are alarming. Obviously the effects of cardiorespiratory depression and fluctuations in the steady state will be most apparent in patients with right-to-left shunts. The present series included eight cyanosed children given bromethol and of these, five showed a rise in arterial oxygen saturation (1-8 per cent), one showed no change and two a fall (2 per cent, 3 per cent). After sedation two cases showed a rise in saturation (2 per cent, 3 per cent), two showed no change, and two falls of 1 per cent and 5 per cent. Under basal narcosis only two cases varied more than 5 per cent during the entire procedure and only one during sampling. After sedation four out of the six cases varied more than 5 per cent, even during sampling. The differences in these proportions are statistically significant
365
366
BRITISH JOURNAL OF ANAESTHESIA
CONCLUSIONS
Basal narcosis using bromethol still provides satisfactory conditions for cardiac catheterization if adequate supervision is available. It is suggested that the initial dose of bromethol should seldom be reduced below 120-125 mg/kg as this lessens the chance of restlessness occurring and reduces the need for supplementary thiopentone. Careful attention to the known causes of pain and discomfort during the investigation will also reduce the need for intravenous anaesthesia. Although patients examined awake but apparently sedated require less supervision during and after the catheterization it appears that many remain anxious and a steady resting state is not in fact achieved. ACKNOWLEDGMENT
The patients examined were under the care of Dr. J. H. Wright, cardiologist to Glasgow Royal Infirmary, and to him and to the late Dr. G. J. Aitken and to Dr. R. M. Thomson I am grateful for their fullest co-operation during these studies. REFERENCES
Adelman, M. H., Rosenthal, A. I., Jacobson, E., and Millis, A. (1952). Anesthetic management in cardiac catheterisation. N.Y. St. J. Med., 52, 1866. Baldwin, E. de V. F., Moore, L. V., and Noble, R. B. (1946). Demonstration of ventricular septal defect by means of right heart catheterisation. Amer. Heart /., 32, 152. Bergen, F. H. van, Weatherhead, S., Treloar A. E., Dobkin, A. B., and Buckley, J. J. (1954). Comparison of indirect and direct methods of measuring arterial blood pressure. Circulation, 10, 481.
Boeson, I., Lind, J., Merrild Hansen, B., Rosendal, T., Storm, O., and Wegelius, C. (1956). The diagnosis of congenital heart disease in infants by catheterisation and selective angiocardiography. Brit. Heart J., 18, 355. Bordley, J., Connor, C. A. R., Hamilton, W. F., Kerr, W. J., and Wiggers, C. J. (1951). Recommendations for the determination of human blood pressure recording by sphygmomanometer. Circulation, 4, 503. Burchell, H. B., Helmholtz, H. F., and Wood, E. H. (1953). Overall experiences with cardiac catheterisation. Proc. Mayo Clin., 28, 50. Wood, E. H. (1949). Reproducibility of values for oxygen saturation of arterial blood in patients with congenital heart disease. /. appl. Physiol., 1, 560. Fieldman, E. J., Lundy, J. S., DuShane, J. W., and Wood, E. H. (1955). Anesthesia for children undergoing diagnostic cardiac catheterisation. Anesthesiology, 16, 868. Harmel, M. H., and Lamont, A. (1946). Anesthesia in surgical treatment of congenital pulmonary stenosis. Anesthesiology. 7, 477. Kepes, E. R., Livingstone, M., and Escher, D. J. W. (1955). Management of children during cardiac catheterisation with inhalation anesthesia. Curr. Res. Anesth. Analg., 34, 299. Kleitman, N. (1929). Sleep. Physiol. Rev., 9, 624. Lucas, B. G. B. (1958). Anoxic states and their management, in Modern Trends in Anaesthesia (eds. Evans, F. T., and Gray, T. C), p. 290. London: Butterworth. Mcllroy, M. B. (1959). The clinical use of oximetry. Brit. Heart j . , 21, 293. Norris, W. (1962). Cardiac catheterization and the anaesthetist. Brit. J. Anaesth., 34, 269. Norton, M. L., and Kubota, Y. (1960). Experiences with cardiac catheterisation using halothane compressed air anesthesia. Anesthesiology, 21, 374. Robin, E. D., Whaley, R. D., Crump, C. H., and Travis, D. M. (1958). Alveolar gas tensions, pulmonary ventilation and blood pH during physiologic sleep in normal subjects. /. clin. Invest., 37, 981. Schnabel, T. G. (1954). Cardiac catheterisation in heart disease. Med. Clin. N. Amer., 38, 16H. Smith, J. A. (1950). Anaesthesia for cardiac catheterisation. Brit. med. J., 1, 705. Wood, P. (1956). Pulmonary circulation and respiratory function. University of St. Andrews, p. 10. (1958). Symposium on congenital heart disease. Brit. Heart ]., 20, 282. L'ANESTHfiSIE DE BASE OU LES SEDATIVES EMPLOYES POUR LE CATH£T£RISME CARDIAQUE SOMMAIRE
Une anesthe'sie de base au brome'thol a 6t6 faite k 63 patients avant catheterisation intra-cardiale. Les modifications circulates et respiratoires e'taient analogues a celles trouvees pendant le sommeil normal. Les fluctuations dans la saturation arterielle en oxygene et dans la tension arterielle pendant la catheterisation etaient en general associees a de 1' agitation ou a 1'administration i.v. de medicaments complementaires. D'autres 59 cas furent etudtes apres sedation proche
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are also known to follow supraventricular tachycardia in such patients during cardiac catheterization without anaesthesia (Schnabel, 1954). It is always tempting, like Kepes et al. (1955), to attribute such troubles to the basal narcosis if this has been given and certainly in this case the respiratory obstruction was an aggravating factor, if not the cause of the trouble. It is well to remember that mishaps, and indeed deaths, have occurred during cardiac catheterization under many different sedative mixtures and that patients with such gross congenital lesions sometimes die suddenly while awaiting the investigation (Burchell et al., 1953; Boeson et al., 1956). This patient however, serves as a reminder of the heavy price to be paid for even the slightest slip in an exacting technique.
BASAL NARCOSIS OR SEDATION FOR CARDIAC CATHETERIZATION de l'e'tat de sommeil. Les resultats variaient, mais lorsque la sedation obtenue etait bonne, les modifications respiratoires et circulatoires etaient similaires a celles survenant apres une anesthesie de base. Chez un nombre de patients dont le nombre inquietait par son ampleur, les signes d'anxiet6 persisterent pendant toute la cathe'terisation et il fut impossible d'obtenir un 6tat de calme. BASISNARKOSE ODER SEDIERUNG FUER HERZKATHETERISIERUNG ZUSAMMENFASSUNG
sich einstellenden Veranderungen in bezug auf Kreislauf und Atmung waren ahnlich wie beim normalen Schlaf. Schwankungen im Sauerstoffgehalt des arteriellen Blutes und Schwankungen des Blutdruckes im grofien Kreislauf traten gewohnlich bei Unruhezustanden oder nach intravenoser Verabfolgung von zusatzlichen Medikamenten auf. Weitere 59 Patienten wurden nach Sedierung bei Schlaflosigkeit beobachtet. Die Ergebnisse waren unterschiedlich, aber bei guter Sedierung fanden sich Veranderungen der Atmung und des Kreislaufes ahnlich denen, wie sie bei der Basisnarkose auftraten. Bei einer unangenehmen grofien Anzahl von Patienten blieben jedoch wahrend der Herzkathederisierung die Erregungszeichen bestehen, ein ausgeglichener Zustand wurde nicht erreicht.
BOOK REVIEW The Regulation of Human Respiration (Proceedings of the J. S. Haldane Centenary Symposium). Edited by D. J. C. Cunningham and B. B. Lloyd. Published by Blackwell Scientific Publications, Oxford. Pp. 591. Price 905. Physiologists from all over the world recently gathered in Oxford to celebrate the centenary of Haldane's birth and to acknowledge his great contribution to the modern understanding of respiration. The proceedings of the symposium are now published in this book which opens with a series of eight tributes from experts in the various fields to which Haldane devoted his life. The first tribute is the original obituary notice written in 1936 for the Royal Society by Professor Douglas. This should be read by every initiate to the study of respiration, for here he will learn the origin of so great a part of the knowledge upon which his own work will be founded. Other contributions in this section include a characteristically lucid account of pulmonary gas exchange by J. H. Comroe and a discussion of Haldane's controversial views on the relation between quantum mechanics and biology by his son, Professor J. B. S. Haldane. Haldane's activity covered so wide a scope that it has not been possible even in this substantial volume to do more than deal with a small part of it. Indeed, the symposium was largely devoted to one aspect of Haldane's interest, the regulation of respiration. This subject is discussed in five of the seven sections of the book, each consisting of original contributions from a number of physiologists active in the field of respiration. The five sections include the peripheral receptors and effectors, the central receptors, the response to carbon dioxide, adaptation to high altitudes and the hyperpnoea of exercise. Each group of papers is followed by a free and lively discussion which is a most valuable feature of the book, but those readers who lack either time or special experience will regret that only a few of the papers and none of the
discussions are concluded by any form of summary. The book concludes with a few short communications relating to other subjects in which Haldane was interested, but inevitably there are many gaps and the publishers' claim that the book "is an authoritative summary of present-day knowledge of respiratory physiology" is not substantiated. Modern knowledge of the distribution of blood and the uptake of gases in the lung derived from such methods as mass spectrometry, carbon monoxide diffusion and radio-isotope techniques would surely have fascinated Haldane, but receive very little attention. Haldane was also concerned with the application of physiological methods to the elucidation of disease in man. Full justice is done to his interest in the disorders of high altitudes and great depths, but there is very little about the physiological investigation of such lung disease as silicosis to which Haldane devoted so much attention. There is not even a reference to some of the measurements of lung function most commonly used in clinical practice today (e.g. the forced expiratory volume, and the peak expiratory flow rate) nor indeed does the spirometer itself merit a place in the index. These criticisms of omission are, however, unfair to the editors who made no such claim as their publishers. They entitled their work The Regulation of Human Respiration and offered it as a tribute to J. S. Haldane. On both these counts the book is a triumph. There is surely no more comprehensive account of the control of respiration nor a more worthy memorial to a great man. The book should be available to every anaesthetist if for no better reason than to correct the impression given by one of the speakers in the symposium. This distinguished physiologist suggested that anaesthetists were suitably unbiased subjects for respiratory experiments because they "did not know much about the control of breathing". Colin Ogilvie
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An 63 Patienten wurde ftir die Herzkathederisierung eine Basisnarkose mit Bromethol verabfolgt. Die
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