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Blood Pressure Changes During Barium Enema
Clinical Radiology (2001) 56: 393±396 doi:10.1053/crad.2000.0664, available online at http://www.idealibrary.com on
Blood Pressure Changes During Barium Enema S. C . ROAC H , O .J .D . M A R T IN, A . OW E N, D . F. M A R T IN Department of Radiology, South Manchester University Hospitals, Manchester, U.K. Received: 20 June 2000
Revised: 3 October 2000
Accepted: 12 October 2000
AIMS: To document blood pressure changes during barium enema examination and to determine at what point in the examination changes are likely to occur. METHODS AND RESULTS: Blood pressure measurements were taken at seven points during the course of barium enema examination in 107 consecutive patients. We found that patients over the age of 60 years had statistically signi®cant decreases in blood pressure when they were stood up during the course of the examination. Many of these patients were asymptomatic. Patients who had symptoms (15/107, 14%) when standing up had a degree of hypotension. The duration of barium enema examination is longer in those patients who experience symptoms. CONCLUSION: During a barium enema examination hypotension occurs at the point of standing up more frequently in patients over 60 years and in those who suer symptoms at this time. Patients who fall into one of these groups should be considered at risk of fainting at this point in the examination. A modi®ed technique to avoid standing should be considered in at-risk patients. Roach, S. C. et al. (2001). # 2001 The Royal College of Radiologists Clinical Radiology 56, 393±396. Key words: barium enema, blood pressure, hypotension.
Barium enemas are performed daily in most U.K. hospitals. Two hundred and ®fty to 300 000 examinations are carried out in the U.K. each year [1], which is equivalent to 500 per 100 000 population. A barium enema is a very safe procedure, with a retrospective survey performed in 1997 reporting a mortality of 1 in 56 786. Deaths are usually the result of bowel perforation or cardiac arrhythmia [1]. However, the incidence of minor complications is much higher, with fainting or light-headedness being the most common. This can result in signi®cant injury and termination or prolongation of the study. The authors have personal knowledge of three cases in which litigation has been sought because of head injuries in two cases and a broken nose in one. The aim of this study was to identify patients at risk of hypotension during barium enema examination and to attempt to identify the particular features of the examination which are responsible for hypotension. This information may allow development of a modi®ed technique in susceptible individuals and thus reduce the incidence of complications. METHOD
One hundred and seven consecutive patients attending for routine out-patient barium enema examination were included in the study. There were no exclusion criteria and Address for correspondence and guarantor of study: Dr D.F. Martin, Department of Radiology, South Manchester University Hospitals, NHS Trust, Manchester M20 2LR, U.K. Fax: 0161 448 1688; E-mail: [email protected] 0009-9260/01/050393+04 $35.00/0
patients ranged from 19 to 88 years old, with an average age of 62.4 years. The group included 73 women and 34 men. Thirty-seven patients were under 60 years old and 70 patients were over 60 years. Patients completed a simple questionnaire regarding general health and medications. A single blood pressure measurement was taken on arrival at the department with the patient sitting at rest and then at six further points during the examination (see Table 1). The pressure measurements were performed using an automated device by one of two operators including a research assistant and a radiologist. The operator timed the duration of the examination, with start time being the point that the patient was in position on the table and the end time being the point of removal of the enema tube. An intravenous smooth muscle relaxant was administered in all cases. This was given after the barium was run in, prior to drainage. Intravenous hyoscine-N-butylbromide (Buscopan, Boehringer Ingelheim, Bracknell, UK) 20 mg Table 1 ± Timing of blood pressure measurements
Measurement Position 1 2 3 4 5 6 7
On arrival at the department Lying on the bed Once barium run in Two minutes after intravenous smooth muscle relaxant Immediately once standing After bed returned to horizontal At end of procedure on bed # 2001 The Royal College of Radiologists
394
CLINICAL RADIOLOGY
Fig. 1 ± Change in blood pressure in the over-60 years age group. Systolic (r), diastolic (j). The time axis represents the seven pre-de®ned points at which blood pressure was taken. Time point 5 represents the point of standing up.
was used as the smooth muscle relaxant in all but four cases, where glucagon (GlucaGen, Novo Nordisk, Crawley, UK) 1 mg was used because of a contraindication to Buscopan. Any symptoms experienced by the patient were documented along with the point in the procedure at which they occurred. Signi®cant symptoms were de®ned as symptoms severe enough to require temporary arrest of the procedure.
RESULTS
Fifteen patients (14.0% of the studied population) suered signi®cant symptoms during the course of the examination and these symptoms were all experienced at the point of standing up. The patients who experienced symptoms ranged in age from 33 to 85 years old, with ®ve being under 60 years and 10 being over 60 years. The average age of this group was 68 years, compared to the average age of the whole group of 62 years. The data suggests that older patients are more likely to be symptomatic but the mean age dierence between those with and without symptoms just failed to be signi®cant at a 90% con®dence interval. None of the patients who had been given glucagon suered symptoms. Symptoms consisted of faintness in 14 of the patients. Several of the patients also experienced nausea. One patient suered nausea and vomiting only. In no case was the procedure abandoned and no patient in this series suered injury. The average time taken to perform the procedure in symptomatic procedures was 46.4 min compared to 32.1 min for the asymptomatic patients. This was statistically signi®cant with a Student's t-test justifying this conclusion at a con®dence level of 99.9%. Statistical analysis of all of the blood pressure measurements using a Mann±Whitney U-test showed that there was a statistically signi®cant (P 5 0.001) fall in diastolic pressure seen in patients over the age of 60 years when
they were stood up during a barium enema examination (Fig. 1). The median fall in diastolic pressure was 5 mmHg, with an interquartile range of ÿ10 to 0. No signi®cant dierence was identi®ed between men and women in this group. Systolic pressure in this age group also showed a fall when the patient stood up, although this was not statistically signi®cant (P 0.59). The median fall was 5 mmHg, with an interquartile range of ÿ10 to 0. Changes in blood pressure were identi®ed in the symptomatic group at the point of standing up although this was not statistically signi®cant (P 0.07 for diastolic and 0.45 for systolic), perhaps due to the small numbers of patients in this group (Fig. 2). The median fall in diastolic pressure for symptomatic patients was 10 mmHg, with an interquartile range of ÿ15 to ÿ5. The median fall in systolic pressure was 10 mmHg, with an interquartile range of ÿ15 to ÿ5. No statistically signi®cant drop in blood pressure was identi®ed in the under-60 years age group at any time during barium enema examination. Median change in diastolic pressure was 0 mmHg, with an interquartile range of ÿ5 to 5. Median change in systolic pressure for this group was ÿ5 mmHg, with an interquartile range of ÿ10 to 0. No statistically signi®cant dierence was identi®ed between the symptomatic and asymptomatic patients in the over60 years age group or in the under-60 years age group, although particularly in the under-60 years age group this may be due to small numbers of symptomatic patients. In summary, our results showed a statistically signi®cant fall in diastolic pressure in the over-60 years age group at the point of standing up. A fall in systolic pressure was also seen in this group at the same point although this was not statistically signi®cant. There was also a trend towards a fall in systolic and diastolic pressure in the symptomatic patients at the point of standing up although this was not statistically signi®cant. The data suggest that older patients are more likely to be symptomatic than younger patients, although this just failed to be signi®cant at a 90% con®dence level. It
BLOOD PRESSURE CHANGES DURING BARIUM ENEMA
395
Fig. 2 ± Changes in blood pressure in symptomatic patients. Systolic (r), diastolic (j). Time axis as in Fig. 1.
was also seen that barium enema examination takes signi®cantly longer to perform in symptomatic patients than in those who remain asymptomatic.
DISCUSSION
Patients may faint during barium enema examinations and there are many potential reasons for this. Before the examination patients are subjected to a restricted diet and a course of laxatives. The patients in this study were on a low ®bre diet for 3 days with ¯uids only on the day prior to the examination. They also took two 10-mg sachets of Picolax (sodium picosulphate) in the 48 h prior to the examination. They were allowed breakfast on the day of the examination. These diet restrictions and laxatives are essential to clean the colon and thus optimize polyp detection, by minimizing faecal residue [2]. However, if ¯uid replacement is inadequate this process can result in dehydration due to excessive ¯uid loss. If dehydration is severe, the reduced circulating volume associated with this can result in peripheral vasoconstriction, tachycardia and hypotension. It has been shown that elderly patients are no more likely to experience problems related to bowel preparation than younger individuals [3]. Patients are also commonly given an anticholinergic smooth muscle relaxant during the examination in order to minimize bowel spasm and to optimize distention. Twenty milligrams of hyoscine-N-butylbromide (Buscopan) allows signi®cantly greater distention of the colon, allows more rapid transit of barium and has been found to have few side-eects, even in the elderly [4,5]. The only commonly encountered side-eect is temporarily blurred vision [5]. Cardiac complications as a consequence of Buscopan occur much more rarely and a survey from 1995 indicated that 2% of radiologists had experienced a cardiac complication in patients given Buscopan [6]. Buscopan works by competitive antagonism of acetylcholine at muscarinic
receptors. Its eects are decreased secretions (salivary, lacrimal, bronchial, sweat and gastric) and pupillary dilatation. Heart rate is initially slowed due to central increased vagal activity but at higher doses tachycardia develops as the cardiac muscarinic receptors are blocked and arrhythmias may also occur. Bronchial, biliary and urinary tract smooth muscles are also relaxed [7]. However, quaternary ammonium antimuscarinics such as Buscopan also have some ganglion blocking properties and can cause postural hypotension at high doses [8]. Glucagon is commonly used as a smooth muscle relaxant in those patients who have a contraindication to the use of Buscopan. Buscopan is the preferred antispasmodic as it is cheaper and produces better distension of the recto-sigmoid colon [5]. The most common reasons to use glucagon instead of Buscopan are glaucoma and urinary out¯ow obstruction. There were four patients in this study who were given glucagon. Glucagon works by having an inhibitory action on tone motility of smooth muscles in the gastro-intestinal tract. It has been reported to cause hypotension, although this is rare [8]. Studies looking at the use of glucagon as an antispasmodic during barium enema examinations have shown no signi®cant side-eects [5]. Gaseous distension of the colon is essential during barium enema in order to optimize the quality of the images. This results in vagal stimulation, which leads to a slowed heart rate and consequently a reduced capacity to increase cardiac output [9]. This would limit the ability of the heart to compensate for decreased blood pressure due to decreased blood volume or decreased peripheral vascular tone. As described previously, blood volume may be reduced due to dehydration from the vigorous bowel cleansing techniques required for diagnostic barium enema, and peripheral tone may be reduced due to the smooth muscle relaxant administered. The vagal stimulation caused by gaseous distension of the colon is likely to exacerbate the inability to increase cardiac output by reducing the heart rate. It has been shown that activation of vagal
396
CLINICAL RADIOLOGY
tone in combination with hypothalamic stimulation by emotional stress causes a greater drop in blood pressure than vagal stimulation alone. This is thought to be due to the vasodilatation within skeletal muscle that occurs in emotional stress [10]. Patients attending for barium enema examination suer both vagal stimulation and hypothalamic stimulation due to emotional stress from fear of the procedure or fear of an intravenous injection and are thus more prone to hypotension. It is common practice to stand patients up during the course of barium enema in order to coat the caecum, drain excess barium from the descending colon and to take double-contrast images of the ¯exures. This is usually performed after the barium has been run around the colon and after the smooth muscle relaxant has been administered. It is at this time that signi®cant falls in blood pressure were noted in the examined group and also the point that patients experienced symptoms. It has been shown in previous studies that arterial blood pressure remains relatively constant in healthy individuals during postural changes [11,12]. However, this study showed that patients over 60 years and those who experience signi®cant symptoms during barium enema examination do experience postural hypotension. It seems likely that a combination of additive features as described above may leave these individuals susceptible to postural hypotension. Previous studies have shown that the preparation of the colon with laxatives, dietary restriction and the use of smooth muscle relaxants improve the quality of the examination and in¯uence the ability to detect subtle colonic pathology [4,2]. No literature is available on the in¯uence of postural change during barium enema on quality of examination or side-eects experienced. It is postulated by this study that change in posture during barium enema examination results in a signi®cant increase in side-eects experienced in certain individuals with no documented bene®t to quality of images achieved. While it may be possible to detect those patients at risk of postural hypotension due to dehydration or autonomic dysfunction by doing a supine and erect blood pressure measurement at the beginning of the examination this would not detect those who suer hypotension due to the other causes mentioned. We feel that in the light of this information it may be appropriate to compare the quality of images obtained when barium enema examination is performed without standing the patient up with images achieved in the standard way. If no signi®cant change in quality is identi®ed it may be
appropriate to examine patients over 60 years and those who experience symptoms without standing them up. We have shown that falls in blood pressure occur in patients over the age of 60 years and those who are symptomatic when they are stood up during barium enema examination. The cause of this is likely to be multifactorial. The use of colonic preparation, dietary restriction, smooth muscle relaxant and colonic distension are likely contributors, but studies have shown that these factors improve the diagnostic quality of the examination. Standing the patient up during the examination will contribute to hypotension in the symptomatic patients and those over 60 years. We feel that it may be appropriate to perform examinations in atrisk individuals without standing them up in order to minimize the number of complications and reduce the number of abandoned or lengthy procedures. Acknowledgements. We would like to thank Mr D. Francis for his advice and assistance in the statistical analysis of the data.
REFERENCES 1 Blakeborough A, Sheridan MB, Chapman AH. Complications of barium enema examinations: a survey of U.K. consultant radiologists 1992 to 1994. Clin Radiol 1997;52:142±148. 2 Lee JR, Ferrando JR. Variables in the preparation of the large intestine for double contrast barium enema examination. Gut 1984;25:69±72. 3 Grad RM, Clar®eld AM, Rosenbloom M, Perrone M. Adequacy of preparation for barium enema among elderly outpatients. Can Med Assoc J 1991;144:1257±1261. 4 Lee JR. Routine use of hyoscine-N-butylbromide in double contrast barium enema examinations. Clin Radiol 1982;33:273±276. 5 Goei R, Nix M, Kessels AH. Use of anti-spasmodics in double contrast barium enema: glucagon or buscopan. Clin Radiol 1995;50:553±557. 6 Fink A, Aylward G. Buscopan and glaucoma: a survey of current practice. Clin Radiol 1995;50:160±164. 7 Rang HP, Dale MM, Ritter MM. Pharmacology, 4th ed. Edinburgh: Church Livingstone, 1999;120±123. 8 Par®tt K, Blake P, Parsons A, et al. Martindale. The Complete Drug Reference, 32nd ed. London: The Pharmaceutical Press. 9 Guyton A. Textbook of Medical Physiology, 7th ed. W. B. Saunders Company, 1986. 10 Niwa H, Hirota Y, Shibutani T, Sugiyama K, Matsuura H. The eects of the hypothalamus on haemodynamic changes elicited by vagal nerve stimulation. Anesthesia Progress 1996;43:41±51. 11 Saijyo T, Nomura M, Narkaya Y, et al. Analysis of blood pressure variability by tonometry. J Gastroenterol Hepatol 1998;13:816±820. 12 Mukai S, Hayano J. Heart rate and blood pressure variabilities during graded head-up tilt. J Appl Physiol 1995;78:212±216.
Blood Pressure Changes During Barium Enema S. C . ROAC H , O .J .D . M A R T IN, A . OW E N, D . F. M A R T IN Department of Radiology, South Manchester University Hospitals, Manchester, U.K. Received: 20 June 2000
Revised: 3 October 2000
Accepted: 12 October 2000
AIMS: To document blood pressure changes during barium enema examination and to determine at what point in the examination changes are likely to occur. METHODS AND RESULTS: Blood pressure measurements were taken at seven points during the course of barium enema examination in 107 consecutive patients. We found that patients over the age of 60 years had statistically signi®cant decreases in blood pressure when they were stood up during the course of the examination. Many of these patients were asymptomatic. Patients who had symptoms (15/107, 14%) when standing up had a degree of hypotension. The duration of barium enema examination is longer in those patients who experience symptoms. CONCLUSION: During a barium enema examination hypotension occurs at the point of standing up more frequently in patients over 60 years and in those who suer symptoms at this time. Patients who fall into one of these groups should be considered at risk of fainting at this point in the examination. A modi®ed technique to avoid standing should be considered in at-risk patients. Roach, S. C. et al. (2001). # 2001 The Royal College of Radiologists Clinical Radiology 56, 393±396. Key words: barium enema, blood pressure, hypotension.
Barium enemas are performed daily in most U.K. hospitals. Two hundred and ®fty to 300 000 examinations are carried out in the U.K. each year [1], which is equivalent to 500 per 100 000 population. A barium enema is a very safe procedure, with a retrospective survey performed in 1997 reporting a mortality of 1 in 56 786. Deaths are usually the result of bowel perforation or cardiac arrhythmia [1]. However, the incidence of minor complications is much higher, with fainting or light-headedness being the most common. This can result in signi®cant injury and termination or prolongation of the study. The authors have personal knowledge of three cases in which litigation has been sought because of head injuries in two cases and a broken nose in one. The aim of this study was to identify patients at risk of hypotension during barium enema examination and to attempt to identify the particular features of the examination which are responsible for hypotension. This information may allow development of a modi®ed technique in susceptible individuals and thus reduce the incidence of complications. METHOD
One hundred and seven consecutive patients attending for routine out-patient barium enema examination were included in the study. There were no exclusion criteria and Address for correspondence and guarantor of study: Dr D.F. Martin, Department of Radiology, South Manchester University Hospitals, NHS Trust, Manchester M20 2LR, U.K. Fax: 0161 448 1688; E-mail: [email protected] 0009-9260/01/050393+04 $35.00/0
patients ranged from 19 to 88 years old, with an average age of 62.4 years. The group included 73 women and 34 men. Thirty-seven patients were under 60 years old and 70 patients were over 60 years. Patients completed a simple questionnaire regarding general health and medications. A single blood pressure measurement was taken on arrival at the department with the patient sitting at rest and then at six further points during the examination (see Table 1). The pressure measurements were performed using an automated device by one of two operators including a research assistant and a radiologist. The operator timed the duration of the examination, with start time being the point that the patient was in position on the table and the end time being the point of removal of the enema tube. An intravenous smooth muscle relaxant was administered in all cases. This was given after the barium was run in, prior to drainage. Intravenous hyoscine-N-butylbromide (Buscopan, Boehringer Ingelheim, Bracknell, UK) 20 mg Table 1 ± Timing of blood pressure measurements
Measurement Position 1 2 3 4 5 6 7
On arrival at the department Lying on the bed Once barium run in Two minutes after intravenous smooth muscle relaxant Immediately once standing After bed returned to horizontal At end of procedure on bed # 2001 The Royal College of Radiologists
394
CLINICAL RADIOLOGY
Fig. 1 ± Change in blood pressure in the over-60 years age group. Systolic (r), diastolic (j). The time axis represents the seven pre-de®ned points at which blood pressure was taken. Time point 5 represents the point of standing up.
was used as the smooth muscle relaxant in all but four cases, where glucagon (GlucaGen, Novo Nordisk, Crawley, UK) 1 mg was used because of a contraindication to Buscopan. Any symptoms experienced by the patient were documented along with the point in the procedure at which they occurred. Signi®cant symptoms were de®ned as symptoms severe enough to require temporary arrest of the procedure.
RESULTS
Fifteen patients (14.0% of the studied population) suered signi®cant symptoms during the course of the examination and these symptoms were all experienced at the point of standing up. The patients who experienced symptoms ranged in age from 33 to 85 years old, with ®ve being under 60 years and 10 being over 60 years. The average age of this group was 68 years, compared to the average age of the whole group of 62 years. The data suggests that older patients are more likely to be symptomatic but the mean age dierence between those with and without symptoms just failed to be signi®cant at a 90% con®dence interval. None of the patients who had been given glucagon suered symptoms. Symptoms consisted of faintness in 14 of the patients. Several of the patients also experienced nausea. One patient suered nausea and vomiting only. In no case was the procedure abandoned and no patient in this series suered injury. The average time taken to perform the procedure in symptomatic procedures was 46.4 min compared to 32.1 min for the asymptomatic patients. This was statistically signi®cant with a Student's t-test justifying this conclusion at a con®dence level of 99.9%. Statistical analysis of all of the blood pressure measurements using a Mann±Whitney U-test showed that there was a statistically signi®cant (P 5 0.001) fall in diastolic pressure seen in patients over the age of 60 years when
they were stood up during a barium enema examination (Fig. 1). The median fall in diastolic pressure was 5 mmHg, with an interquartile range of ÿ10 to 0. No signi®cant dierence was identi®ed between men and women in this group. Systolic pressure in this age group also showed a fall when the patient stood up, although this was not statistically signi®cant (P 0.59). The median fall was 5 mmHg, with an interquartile range of ÿ10 to 0. Changes in blood pressure were identi®ed in the symptomatic group at the point of standing up although this was not statistically signi®cant (P 0.07 for diastolic and 0.45 for systolic), perhaps due to the small numbers of patients in this group (Fig. 2). The median fall in diastolic pressure for symptomatic patients was 10 mmHg, with an interquartile range of ÿ15 to ÿ5. The median fall in systolic pressure was 10 mmHg, with an interquartile range of ÿ15 to ÿ5. No statistically signi®cant drop in blood pressure was identi®ed in the under-60 years age group at any time during barium enema examination. Median change in diastolic pressure was 0 mmHg, with an interquartile range of ÿ5 to 5. Median change in systolic pressure for this group was ÿ5 mmHg, with an interquartile range of ÿ10 to 0. No statistically signi®cant dierence was identi®ed between the symptomatic and asymptomatic patients in the over60 years age group or in the under-60 years age group, although particularly in the under-60 years age group this may be due to small numbers of symptomatic patients. In summary, our results showed a statistically signi®cant fall in diastolic pressure in the over-60 years age group at the point of standing up. A fall in systolic pressure was also seen in this group at the same point although this was not statistically signi®cant. There was also a trend towards a fall in systolic and diastolic pressure in the symptomatic patients at the point of standing up although this was not statistically signi®cant. The data suggest that older patients are more likely to be symptomatic than younger patients, although this just failed to be signi®cant at a 90% con®dence level. It
BLOOD PRESSURE CHANGES DURING BARIUM ENEMA
395
Fig. 2 ± Changes in blood pressure in symptomatic patients. Systolic (r), diastolic (j). Time axis as in Fig. 1.
was also seen that barium enema examination takes signi®cantly longer to perform in symptomatic patients than in those who remain asymptomatic.
DISCUSSION
Patients may faint during barium enema examinations and there are many potential reasons for this. Before the examination patients are subjected to a restricted diet and a course of laxatives. The patients in this study were on a low ®bre diet for 3 days with ¯uids only on the day prior to the examination. They also took two 10-mg sachets of Picolax (sodium picosulphate) in the 48 h prior to the examination. They were allowed breakfast on the day of the examination. These diet restrictions and laxatives are essential to clean the colon and thus optimize polyp detection, by minimizing faecal residue [2]. However, if ¯uid replacement is inadequate this process can result in dehydration due to excessive ¯uid loss. If dehydration is severe, the reduced circulating volume associated with this can result in peripheral vasoconstriction, tachycardia and hypotension. It has been shown that elderly patients are no more likely to experience problems related to bowel preparation than younger individuals [3]. Patients are also commonly given an anticholinergic smooth muscle relaxant during the examination in order to minimize bowel spasm and to optimize distention. Twenty milligrams of hyoscine-N-butylbromide (Buscopan) allows signi®cantly greater distention of the colon, allows more rapid transit of barium and has been found to have few side-eects, even in the elderly [4,5]. The only commonly encountered side-eect is temporarily blurred vision [5]. Cardiac complications as a consequence of Buscopan occur much more rarely and a survey from 1995 indicated that 2% of radiologists had experienced a cardiac complication in patients given Buscopan [6]. Buscopan works by competitive antagonism of acetylcholine at muscarinic
receptors. Its eects are decreased secretions (salivary, lacrimal, bronchial, sweat and gastric) and pupillary dilatation. Heart rate is initially slowed due to central increased vagal activity but at higher doses tachycardia develops as the cardiac muscarinic receptors are blocked and arrhythmias may also occur. Bronchial, biliary and urinary tract smooth muscles are also relaxed [7]. However, quaternary ammonium antimuscarinics such as Buscopan also have some ganglion blocking properties and can cause postural hypotension at high doses [8]. Glucagon is commonly used as a smooth muscle relaxant in those patients who have a contraindication to the use of Buscopan. Buscopan is the preferred antispasmodic as it is cheaper and produces better distension of the recto-sigmoid colon [5]. The most common reasons to use glucagon instead of Buscopan are glaucoma and urinary out¯ow obstruction. There were four patients in this study who were given glucagon. Glucagon works by having an inhibitory action on tone motility of smooth muscles in the gastro-intestinal tract. It has been reported to cause hypotension, although this is rare [8]. Studies looking at the use of glucagon as an antispasmodic during barium enema examinations have shown no signi®cant side-eects [5]. Gaseous distension of the colon is essential during barium enema in order to optimize the quality of the images. This results in vagal stimulation, which leads to a slowed heart rate and consequently a reduced capacity to increase cardiac output [9]. This would limit the ability of the heart to compensate for decreased blood pressure due to decreased blood volume or decreased peripheral vascular tone. As described previously, blood volume may be reduced due to dehydration from the vigorous bowel cleansing techniques required for diagnostic barium enema, and peripheral tone may be reduced due to the smooth muscle relaxant administered. The vagal stimulation caused by gaseous distension of the colon is likely to exacerbate the inability to increase cardiac output by reducing the heart rate. It has been shown that activation of vagal
396
CLINICAL RADIOLOGY
tone in combination with hypothalamic stimulation by emotional stress causes a greater drop in blood pressure than vagal stimulation alone. This is thought to be due to the vasodilatation within skeletal muscle that occurs in emotional stress [10]. Patients attending for barium enema examination suer both vagal stimulation and hypothalamic stimulation due to emotional stress from fear of the procedure or fear of an intravenous injection and are thus more prone to hypotension. It is common practice to stand patients up during the course of barium enema in order to coat the caecum, drain excess barium from the descending colon and to take double-contrast images of the ¯exures. This is usually performed after the barium has been run around the colon and after the smooth muscle relaxant has been administered. It is at this time that signi®cant falls in blood pressure were noted in the examined group and also the point that patients experienced symptoms. It has been shown in previous studies that arterial blood pressure remains relatively constant in healthy individuals during postural changes [11,12]. However, this study showed that patients over 60 years and those who experience signi®cant symptoms during barium enema examination do experience postural hypotension. It seems likely that a combination of additive features as described above may leave these individuals susceptible to postural hypotension. Previous studies have shown that the preparation of the colon with laxatives, dietary restriction and the use of smooth muscle relaxants improve the quality of the examination and in¯uence the ability to detect subtle colonic pathology [4,2]. No literature is available on the in¯uence of postural change during barium enema on quality of examination or side-eects experienced. It is postulated by this study that change in posture during barium enema examination results in a signi®cant increase in side-eects experienced in certain individuals with no documented bene®t to quality of images achieved. While it may be possible to detect those patients at risk of postural hypotension due to dehydration or autonomic dysfunction by doing a supine and erect blood pressure measurement at the beginning of the examination this would not detect those who suer hypotension due to the other causes mentioned. We feel that in the light of this information it may be appropriate to compare the quality of images obtained when barium enema examination is performed without standing the patient up with images achieved in the standard way. If no signi®cant change in quality is identi®ed it may be
appropriate to examine patients over 60 years and those who experience symptoms without standing them up. We have shown that falls in blood pressure occur in patients over the age of 60 years and those who are symptomatic when they are stood up during barium enema examination. The cause of this is likely to be multifactorial. The use of colonic preparation, dietary restriction, smooth muscle relaxant and colonic distension are likely contributors, but studies have shown that these factors improve the diagnostic quality of the examination. Standing the patient up during the examination will contribute to hypotension in the symptomatic patients and those over 60 years. We feel that it may be appropriate to perform examinations in atrisk individuals without standing them up in order to minimize the number of complications and reduce the number of abandoned or lengthy procedures. Acknowledgements. We would like to thank Mr D. Francis for his advice and assistance in the statistical analysis of the data.
REFERENCES 1 Blakeborough A, Sheridan MB, Chapman AH. Complications of barium enema examinations: a survey of U.K. consultant radiologists 1992 to 1994. Clin Radiol 1997;52:142±148. 2 Lee JR, Ferrando JR. Variables in the preparation of the large intestine for double contrast barium enema examination. Gut 1984;25:69±72. 3 Grad RM, Clar®eld AM, Rosenbloom M, Perrone M. Adequacy of preparation for barium enema among elderly outpatients. Can Med Assoc J 1991;144:1257±1261. 4 Lee JR. Routine use of hyoscine-N-butylbromide in double contrast barium enema examinations. Clin Radiol 1982;33:273±276. 5 Goei R, Nix M, Kessels AH. Use of anti-spasmodics in double contrast barium enema: glucagon or buscopan. Clin Radiol 1995;50:553±557. 6 Fink A, Aylward G. Buscopan and glaucoma: a survey of current practice. Clin Radiol 1995;50:160±164. 7 Rang HP, Dale MM, Ritter MM. Pharmacology, 4th ed. Edinburgh: Church Livingstone, 1999;120±123. 8 Par®tt K, Blake P, Parsons A, et al. Martindale. The Complete Drug Reference, 32nd ed. London: The Pharmaceutical Press. 9 Guyton A. Textbook of Medical Physiology, 7th ed. W. B. Saunders Company, 1986. 10 Niwa H, Hirota Y, Shibutani T, Sugiyama K, Matsuura H. The eects of the hypothalamus on haemodynamic changes elicited by vagal nerve stimulation. Anesthesia Progress 1996;43:41±51. 11 Saijyo T, Nomura M, Narkaya Y, et al. Analysis of blood pressure variability by tonometry. J Gastroenterol Hepatol 1998;13:816±820. 12 Mukai S, Hayano J. Heart rate and blood pressure variabilities during graded head-up tilt. J Appl Physiol 1995;78:212±216.