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1st World Congress on Intensive Care
1ST WORLD
CONGRESS
The first World Congress on Intensive Care was held at the Imperial College, London from 24 to 27 June 1974. The following papers of interest to our readers were presented at this Congress.
ON INTENSIVE
2.
Continuous Monitoring of Intracranial Pressure, of the Echo Median and of the EEG Y. LAZORTHES, L. CAMPAN, P. JAUSSERAND,B. AZALBERTand J. BUFFET Toulouse,
1.
Pulsatile Ultrasonic Monitoring of Cerebral Circulation during Coma, and its Particular Value in Irreversible Coma J. M. LEPETIT, J. P. PEFFERKORN,A. R. GAY and G. LEJEUNE Limoges. It 1s
DANY,
France.
accepted that in order to establish Irrefutable proof of the absence of carotid circulation, three methods are possible carottd angiography, the isotopic method, and stnce 1968 the investigation and study of ultrasonic pulsatile echoes. Lepetit et ui. The existence of pulsatile intracranial echoes confirms the integrity of the cerebral circulation: on the other hand. their abolitton is a sign of cerebral death. This method never falls: it is simple. non-traumatic and can be repeated as desired and is automatically available by continuous monitoring, it IS applicable in all places. it Immediately gives a posttive or negattv>e response and may be visualized by graphic tracing (Pulsatile Echo Monitor). To this diagnostic feature is added a major prognostic advantage in stage 11I coma (along with Grade IV comas of toxic origin): in fact. the persistence of pulsatile echoes means. that there may be hope of recovery and thus confirms the suitability of the brain for treatment. With reference tc> Grade IV coma. in “donor” subjects being considered for organ grafting. complete certainty of diagnoses seems to us to be assured by taking the following three criteria into account: I. Clinical signs: signs of irreversible coma 2. EEG: no trace (no activity) 3. Ultrasonic pulsatile echography: abolition of the hemispheric echoes. WC have developed. in collaboration with electronic engineers. an almost fully automatic apparatus for the investigation of pulsatile echoes: the Pulsatile Echo Monitor. comprtsing 16 channels which can function separately centimeter by centimeter across the diameter of the brain. thus giving a qualitative view of the /onal hemtsphere circulation. It also functions in additron as a method which evaluation of the overall cerebral gives a quantttativ’e hemisphertc circulation.
CARE
France.
Supervision of postoperative neurosurgical patients and those with head injuries IS still essentially based on clinical features. Monitoring equipment as used at present provides information on peripheral phystological parameters only. These parameters can give only indirect evidence for impairment of cerebral function and the development of complications. Indications for neuro-radiological diagnostic studies and for therapeutic steps could be put on a much firmer basis of specificparameters such as intracranial by the monitoring pressure, the echo median and the EEG. Intracranial pressure is the most important factor in assessing the role of intracranial hypertension and impairment of cerebral function in a worsening clinical SituatiOn. Present therapeutic measures for the lowering of intracranial pressure are very effective, and they can be dangerous if used in a routine and uncontrolled manner. Manometry of the lumbar spinal fluid provtdes only indirect information. and there is some risk in repeated lumbar punctures. Changes of intracrantal pressure can be very rapid. and so there IS a need for continuous monitoring. We have devised a sensor for I.P.. conststing of a miniaturized capsule which can be implanted into the extradurdl space of the cranial vault. As has been shown by expertmental studies. the sensor* has an excellent sensitivity for pressure (I mV;H20), and there have been no changes in sensittvity with varying temperatures and over a prolonged period of time. As the unit can be operated by very small currents. telemetry will finally be possible, but the device tn present use IS connected by wires. In unidirectional echo-encephalography (or echo A). the position of the median line IS identified with the aid of 2 sensors and 4 traces. The echo-encephalogram is displayed on the screen of an oscilloscope, pictures being taken with the aid of a Polaroid system. The shape of the median echo is specific. In order to get a better demonstration of shifts of the echo median. 2 bilateral and symmetric traces arc recorded. This simple and atraumatic diagnostic procedure can be easily repeated. thus taking advantage of the greater significance of a dynamic study. In the acute phase. the EEG too is of interest for the detection of focal depression of cerebral function as well as for the demonstration of irritative phenomena. lt will be
471
472
1st World Congress
made more meaningful by the possibility of repetitive examinations. In this way it can be Interpreted in relation to other data. The EEG is registered by an array of three clec(rodes placed subcutaneously in the scalp. Recording is llmited to a single trace. The whole assembly for amplification, visualization and recording of these three parameters is constructed according to the modular principle. Each untt can be integrated, in the form of a functional drawer, into the standard arrangement cardiovascular recording equipment. This electronic equipment is suitable for the supervision of operated and traumatized neurosurgical patients. and it momtoring”. It constitutes a step toward “neurosurgical will permit assessment of the effect of hypotensive treatment by objectlvc criteria, and it will enable us to act earlier and with more precision in patients whose clinical picture deteriorates or simply fails to Improve.
3.
Pilot Evaluation graph
of Transcutaneous
Aortoveb
L. H. LIGHT, G. CROSS, GILLIAN C. HANSON and R. PEISACH
Clinical Research Centre, Harrow, Middlesex, Cross Hospital, Leytonstone. London E. 1I.
Whipps
In many conditions measurements of blood pressure correlate so badly with body perfusion that a comparatively simple method of following changes m systemic blood flow should have much to offer in intensive care. In this belief we have developed a non-invasive technique, based on the ultrasonic Doppler principle, which gives a consistent
on Intensive
Care
index of a closely related variable, the mstantancous tlow velocity in the transverse aorta of the patient. A paper record of phasic mainstream blood velocity is produced by analysis of the signal obtained from a transducer which is placed on the suprasternal notch. Systolic flow appears as dlscretc wave-forms, the areas of which arc an index of stroke volume, the highest point of the wave representing peak velocity, and the base ventricular ejectlon time. Approximate proportionality would be expected between the observed velocity and flow rate m any one patient whenever. as will normally be the case, the aortlc cross-section transverse How profile and the fraction of cardiac output lost to observation into prior branches remain fairly constant. Pilot experimental comparisons with accepted measures of cardiac output and intraluminal velocity sensors confirm that good proportionality is obtainable in practice. Application of the technique to intensive therapy was assessed at Whipps Cross Hospital over a 4 month period. During this time Instantaneous blood velocity in the transverse aorta was recorded in 84 patients admitted to the unit. Twenty normal subjects were also investigated and these were used as a basis for comparison. Twenty-one patients with myocardtal infarctton and 12 In a variety of shock states were investigated. Serial recordings were used to follow changes In cardiovascular states in response to therapeutic manoeuvres such as. blood volume replacement. positive pressure ventilation, posltlvc end-explratory pressure, peritoneal dialysis. rapid antlhypertenslve and peripheral vasodilator drug therapy. Our findings confirmed the changes in wale form as a result oftherapy. or change in medical condition. were easily Interpreted and are likely to be of value in the management of crltlcally ill patients.
CONGRESS
The first World Congress on Intensive Care was held at the Imperial College, London from 24 to 27 June 1974. The following papers of interest to our readers were presented at this Congress.
ON INTENSIVE
2.
Continuous Monitoring of Intracranial Pressure, of the Echo Median and of the EEG Y. LAZORTHES, L. CAMPAN, P. JAUSSERAND,B. AZALBERTand J. BUFFET Toulouse,
1.
Pulsatile Ultrasonic Monitoring of Cerebral Circulation during Coma, and its Particular Value in Irreversible Coma J. M. LEPETIT, J. P. PEFFERKORN,A. R. GAY and G. LEJEUNE Limoges. It 1s
DANY,
France.
accepted that in order to establish Irrefutable proof of the absence of carotid circulation, three methods are possible carottd angiography, the isotopic method, and stnce 1968 the investigation and study of ultrasonic pulsatile echoes. Lepetit et ui. The existence of pulsatile intracranial echoes confirms the integrity of the cerebral circulation: on the other hand. their abolitton is a sign of cerebral death. This method never falls: it is simple. non-traumatic and can be repeated as desired and is automatically available by continuous monitoring, it IS applicable in all places. it Immediately gives a posttive or negattv>e response and may be visualized by graphic tracing (Pulsatile Echo Monitor). To this diagnostic feature is added a major prognostic advantage in stage 11I coma (along with Grade IV comas of toxic origin): in fact. the persistence of pulsatile echoes means. that there may be hope of recovery and thus confirms the suitability of the brain for treatment. With reference tc> Grade IV coma. in “donor” subjects being considered for organ grafting. complete certainty of diagnoses seems to us to be assured by taking the following three criteria into account: I. Clinical signs: signs of irreversible coma 2. EEG: no trace (no activity) 3. Ultrasonic pulsatile echography: abolition of the hemispheric echoes. WC have developed. in collaboration with electronic engineers. an almost fully automatic apparatus for the investigation of pulsatile echoes: the Pulsatile Echo Monitor. comprtsing 16 channels which can function separately centimeter by centimeter across the diameter of the brain. thus giving a qualitative view of the /onal hemtsphere circulation. It also functions in additron as a method which evaluation of the overall cerebral gives a quantttativ’e hemisphertc circulation.
CARE
France.
Supervision of postoperative neurosurgical patients and those with head injuries IS still essentially based on clinical features. Monitoring equipment as used at present provides information on peripheral phystological parameters only. These parameters can give only indirect evidence for impairment of cerebral function and the development of complications. Indications for neuro-radiological diagnostic studies and for therapeutic steps could be put on a much firmer basis of specificparameters such as intracranial by the monitoring pressure, the echo median and the EEG. Intracranial pressure is the most important factor in assessing the role of intracranial hypertension and impairment of cerebral function in a worsening clinical SituatiOn. Present therapeutic measures for the lowering of intracranial pressure are very effective, and they can be dangerous if used in a routine and uncontrolled manner. Manometry of the lumbar spinal fluid provtdes only indirect information. and there is some risk in repeated lumbar punctures. Changes of intracrantal pressure can be very rapid. and so there IS a need for continuous monitoring. We have devised a sensor for I.P.. conststing of a miniaturized capsule which can be implanted into the extradurdl space of the cranial vault. As has been shown by expertmental studies. the sensor* has an excellent sensitivity for pressure (I mV;H20), and there have been no changes in sensittvity with varying temperatures and over a prolonged period of time. As the unit can be operated by very small currents. telemetry will finally be possible, but the device tn present use IS connected by wires. In unidirectional echo-encephalography (or echo A). the position of the median line IS identified with the aid of 2 sensors and 4 traces. The echo-encephalogram is displayed on the screen of an oscilloscope, pictures being taken with the aid of a Polaroid system. The shape of the median echo is specific. In order to get a better demonstration of shifts of the echo median. 2 bilateral and symmetric traces arc recorded. This simple and atraumatic diagnostic procedure can be easily repeated. thus taking advantage of the greater significance of a dynamic study. In the acute phase. the EEG too is of interest for the detection of focal depression of cerebral function as well as for the demonstration of irritative phenomena. lt will be
471
472
1st World Congress
made more meaningful by the possibility of repetitive examinations. In this way it can be Interpreted in relation to other data. The EEG is registered by an array of three clec(rodes placed subcutaneously in the scalp. Recording is llmited to a single trace. The whole assembly for amplification, visualization and recording of these three parameters is constructed according to the modular principle. Each untt can be integrated, in the form of a functional drawer, into the standard arrangement cardiovascular recording equipment. This electronic equipment is suitable for the supervision of operated and traumatized neurosurgical patients. and it momtoring”. It constitutes a step toward “neurosurgical will permit assessment of the effect of hypotensive treatment by objectlvc criteria, and it will enable us to act earlier and with more precision in patients whose clinical picture deteriorates or simply fails to Improve.
3.
Pilot Evaluation graph
of Transcutaneous
Aortoveb
L. H. LIGHT, G. CROSS, GILLIAN C. HANSON and R. PEISACH
Clinical Research Centre, Harrow, Middlesex, Cross Hospital, Leytonstone. London E. 1I.
Whipps
In many conditions measurements of blood pressure correlate so badly with body perfusion that a comparatively simple method of following changes m systemic blood flow should have much to offer in intensive care. In this belief we have developed a non-invasive technique, based on the ultrasonic Doppler principle, which gives a consistent
on Intensive
Care
index of a closely related variable, the mstantancous tlow velocity in the transverse aorta of the patient. A paper record of phasic mainstream blood velocity is produced by analysis of the signal obtained from a transducer which is placed on the suprasternal notch. Systolic flow appears as dlscretc wave-forms, the areas of which arc an index of stroke volume, the highest point of the wave representing peak velocity, and the base ventricular ejectlon time. Approximate proportionality would be expected between the observed velocity and flow rate m any one patient whenever. as will normally be the case, the aortlc cross-section transverse How profile and the fraction of cardiac output lost to observation into prior branches remain fairly constant. Pilot experimental comparisons with accepted measures of cardiac output and intraluminal velocity sensors confirm that good proportionality is obtainable in practice. Application of the technique to intensive therapy was assessed at Whipps Cross Hospital over a 4 month period. During this time Instantaneous blood velocity in the transverse aorta was recorded in 84 patients admitted to the unit. Twenty normal subjects were also investigated and these were used as a basis for comparison. Twenty-one patients with myocardtal infarctton and 12 In a variety of shock states were investigated. Serial recordings were used to follow changes In cardiovascular states in response to therapeutic manoeuvres such as. blood volume replacement. positive pressure ventilation, posltlvc end-explratory pressure, peritoneal dialysis. rapid antlhypertenslve and peripheral vasodilator drug therapy. Our findings confirmed the changes in wale form as a result oftherapy. or change in medical condition. were easily Interpreted and are likely to be of value in the management of crltlcally ill patients.