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(Radiology. 2000;216:660-664.)
© RSNA, 2000

Special Report

Conscious Sedation and Analgesia for Routine Aortofemoral Arteriography: A Prospective Evaluation1

Peter T. Kennedy, FRCSI, FRCR, Ian M. G. Kelly, MRCPI, FRCR, William C. Loan, FRCS, FRCR and Chris S. Boyd, FRCS

1 From the Department of Radiology, the Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BA, Northern Ireland (P.T.K., I.M.G.K., W.C.L., C.S.B.), and the Belfast City Hospital, Northern Ireland (P.T.K., W.C.L.). From the 1998 RSNA scientific assembly. Received June 14, 1999; revision requested August 3; revision received December 16; accepted January 12, 2000. Address correspondence to P.T.K. (e-mail: ptkennedy@classicfm.net).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
PURPOSE: To compare the effectiveness of temazepam and midazolam hydrochloride with or without fentanyl citrate versus a placebo in promoting patient acceptance of diagnostic aortofemoral arteriography.

MATERIALS AND METHODS: One hundred twenty-five patients undergoing aortofemoral arteriography were prospectively and randomly assigned to one of four treatment arms: placebo (group A), oral temazepam (group B), intravenous midazolam (group C), or intravenous midazolam and fentanyl (group D). Patients were blinded to the administered sedative. Five-point scales were used to assess degree of patient discomfort, willingness to undergo the same procedure again, patient compliance, and preprocedural anxiety.

RESULTS: There was no difference between patient groups in willingness to return for a repeat procedure (P = .89). Group C patients were less compliant during the procedure (P = .034). Mean patient discomfort scores were 1.81 for group A , 1.84 for group B, 1.53 for group C, and 1.27 for group D. Discomfort experienced during the procedure was not related to the degree of preprocedural anxiety (P = .42). Patients who had previously undergone arteriography reported a higher level of pain than did those who had not (P = .021).

CONCLUSION: Most patients experienced only low-level discomfort during diagnostic aortofemoral arteriography. In the authors’ opinion, conscious sedation should only be used selectively, not routinely, for diagnostic aortofemoral arteriography.

Index terms: Anesthesia, 92.64 • Angiography, 92.122 • Arteries, extremities • Arteries, stenosis or obstruction, 92.721 • Arteriosclerosis, 92.721 • Drugs, 92.64


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Aortofemoral arteriography is a common diagnostic procedure performed in patients with evidence of peripheral vascular disease. There is wide variation in the administration of sedatives and analgesics during this procedure, ranging from none to a combination of intravenously administered opiates and benzodiazepines (1,2). Developments in radiologic equipment and contrast media have resulted in changes in technique, which have undoubtedly changed the experience of arteriography from the patient’s perspective: Nonionic contrast media are less hyperosmolar than ionic contrast media and are associated with less discomfort during injection; digital imaging allows the use of a reduced volume of contrast medium during each bolus injection, which also results in less discomfort (3,4).

Pharmacologic sedation is widely used in many branches of medicine and is safe; nevertheless, both intravenous benzodiazepines and narcotics have cardiorespiratory depressant effects (5). Atherosclerosis is a systemic disease, and most patients with peripheral vascular disease will die of a myocardial event or cerebrovascular accident (6); therefore, the population of patients undergoing aortofemoral arteriography are particularly vulnerable to the risks involved in the use of these drugs.

This study was designed to assess the need for sedation and analgesia during aortofemoral arteriography and to try to identify any subgroups within the patient population who may benefit particularly from the use of benzodiazepines and narcotics.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Patients referred to the radiology departments of two university teaching hospitals (Royal Victoria Hospital and Belfast City Hospital, Northern Ireland) for diagnostic lower limb arteriography were eligible for inclusion in the study. Patients referred for vascular intervention or additional arteriography during the same procedure (eg, aortic arch arteriography) were excluded. The research ethical committees of both hospitals approved the trial, and all patients provided written informed consent for inclusion in the trial. Exclusion criteria were as follows: (a) known allergy to benzodiazepines or narcotics, (b) documented history of liver disease or severe respiratory compromise, (c) administration of analgesic or sedative drugs within 2 hours of the diagnostic study, (d) performance of any interventional procedure during the examination.

Patients were entered consecutively into the trial, and a total of 125 patients (83 men, 42 women) aged 43–93 years (mean age, 67.8 years) were recruited. Forty-three patients had symptoms and signs of critical ischemia, which manifested as pain at rest or tissue loss.

Each patient was administered a tablet 1 hour before the procedure and an intravenous injection once he or she had been prepared and draped in the angiographic suite. The nature of the tablet and injection depended on which of the four study groups the patient was randomly allocated to: Group A received a placebo tablet and a saline solution injection; group B, 10-mg temazepam and a saline solution injection; group C, a placebo tablet and a midazolam hydrochloride injection; or group D, a placebo tablet and midazolam and fentanyl citrate injections (Table 1). The patients were blinded to treatment; local sedation policy prevented blinding of the radiologist and nurse to the treatment.


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  		TABLE 1. Mean Drug Dose for Each Patient Group
 
Midazolam was administered at a loading dose of 14 µg per kilogram body weight (1 mg per 70 kg), with additional maintenance doses of 7 µg/kg after intervals of no less than 3 minutes. Fentanyl was administered at a loading dose of 0.71 µg/kg (50 µg per 70 kg) 3 minutes after administration of midazolam. Maintenance doses of 0.71 µg/kg were also delivered. The patient was maintained in a state of reduced perception: Eyelid ptosis and slurred speech were signs that the patient was adequately sedated but could be roused at all times and could respond to verbal commands. In group D, the administration of each drug was alternated, no less than 3 minutes apart, until the desired level of sedation was reached. The drugs were administered by an assisting physician. Patients in groups C and D were monitored with continuous observation of oxygen saturation and pulse measurements and intermittent noninvasive blood pressure measurement. A qualified nurse was responsible for monitoring and recording these observations. Oxygen was routinely administered to these patients by means of a face mask or nasal cannula at a rate of 3 L/min.

All patients received a subcutaneous injection of 2% lidocaine hydrochloride at the intended site of skin puncture. A common femoral arterial access was used in each patient. With a pigtail catheter positioned in the distal aorta, a 90-mL solution of nonionic monomeric contrast medium (iopamidol, Niopam; Bracco, Milan, Italy) containing 300 mg iodine per milliliter was injected at a rate of 9 mL/sec. A step table with five stations was used with a rapid film changer to obtain conventional radiographs during vessel opacification. Digital subtraction angiography was used to obtain oblique views and images of the distal vessels when initial conventional images were inadequate.

An assessment of each patient’s anxiety level was made prior to each examination by one of the authors (P.T.K., W.C.L., C.S.B.) by using a five-point analog scale with descriptors, as follows: score of 1, completely relaxed; score of 2, slightly tense; score of 3, moderately concerned; score of 4, very nervous; and score of 5, terrified. After the procedure, the radiologist and the nurse independently provided their interpretations of the pain experienced by the patient during the procedure. The radiologist also recorded the level of patient compliance and the technical difficulty of the procedure (Table 2). At least 6 hours after the procedure, each patient was asked to rate the pain experienced during the procedure and whether they would undergo the examination again if their physician recommended it. A five-point analog scale was used for each of these observations and responses. Descriptors associated with the increments for the pain assessment by radiologist, patient, and nurse were as follows: score of 1, no pain or discomfort; score of 2, minimal discomfort; score of 3, some pain; score of 4, bad pain; score of 5, severe pain.


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  		TABLE 2. Scores and Descriptors for Radiologists’ Ratings of Patient Compliance, Technical Difficulty, and Patient Willingness to Repeat the Procedure
 
Analysis of the data was performed by using Cochran-Mantel-Haenszel statistics, which are suitable for nonparametric discrete data (SAS/STAT user’s guide version 6, 4th ed; SAS Institute, Cary, NC).


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
The level of patient-reported pain in all the treatment arms was low (Figs 1, 2). The mean pain score for patients in the placebo group was 1.81. There was, however, a significant difference between the groups (P = .008), which remained significant when the scores were stratified according anxiety level before the procedure and the presence of critical ischemia. The lowest mean patient-reported pain score (mean, 1.27) was seen in group D; this score was significantly lower than that in the placebo group (group A) (P = .002, with significance achieved when P = .05/6; ie, P = .008 [Bonferroni correction]) (7). Although the mean pain score in group C was lower than that in group A, the difference was not significant.



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  		Figure 1. Graph shows ranges (vertical bars) and means (µ, horizontal hash marks) of pain scores for each treatment arm (patient group). The pain scores on the y axis are represented by their associated descriptors. min = minimal.

 


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  		Figure 2. Bar graph shows breakdown of pain scores for each treatment arm (patient group). The pain scores are represented by their associated descriptors. min = minimal.

 
There was a significant difference between treatment groups in the assessment of patient compliance (P = .034); this difference was also seen when the results were stratified according to the technical difficulty of the procedure. The least compliant patients were in group C, and, when compared with those in the placebo group, the difference was significant. (P = .003 [Bonferroni correction]). There was no difference in patient compliance when comparing the placebo group and group D.

When the patients were asked to rate their willingness to return for another arteriographic examination, if indicated, there was no difference between groups (P = .89). One hundred nine (87.2%) of 125 patients gave a score of 1, which indicated that they would return for arteriography without hesitation.

There was no association between preprocedural anxiety and pain experienced (P = .42). Fifty-eight (89%) of the 65 patients who expressed any concern about the procedure (anxiety score >= 2) reported either no pain or mild discomfort. There also was not any association between pain experienced and the presence of critical ischemia or patient age.

Those patients who had previously undergone arteriography described a higher level of pain than did those who had not (P = .021), although the same group of patients expressed less anxiety before the procedure (P = .042). Women expressed more anxiety before the procedure than did men (P = .04) but did not report more postprocedural discomfort than did men (P = .3).

The patients’ expression of discomfort was compared with the radiologists’ and nurses’ interpretations of patient discomfort during the procedure. The radiologists’ and nurses’ opinions were well correlated (Kendall {tau} rank-correlation coefficient = 0.55), but neither the radiologists nor the nurses predicted well which patients would express pain or discomfort (Kendall {tau} rank-correlation coefficients: radiologist vs patient, 0.30; nurse vs patient, 0.23). However, an increased degree of difficulty, as recorded by the radiologist, was associated with an increase in the patient pain score (Table 3). This finding did not quite reach statistical significance (P = .081)


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  		TABLE 3. Correlation between Technical Difficulty of Procedure and Patient-reported Pain
 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
Patient satisfaction and measures of outcome from the patient’s perspective are becoming increasingly important. Periprocedural pain and discomfort constitute one area of medicine that has come under particular scrutiny (8). The use of sedatives and analgesics for diagnostic angiography varies greatly from center to center, whereas many publications on the subject have started from the standpoint that some form of analgesia and anxiolysis is desirable, be it pharmacologic or behavioral (2). The developments of less hyperosmolar contrast media and digital subtraction angiography have together helped reduce the contrast medium volume required during angiography, which has reduced the discomfort experienced by patients (3,4). To our knowledge, there have been no prospective, placebo-controlled, randomized, blinded studies reported in the literature that demonstrate that sedation improves the patient’s experience during diagnostic angiography or, more important, that the risk-benefit ratio is favorably altered by the use of sedatives and analgesics.

The authors of one study (9) have shown that a combination of fentanyl and midazolam provided greater anxiolysis than did midazolam alone when used during diagnostic angiography. The results of that study were weakened, however, owing to the absence of a placebo group; therefore, the anxiolytic effect of the completion of the procedure could not be taken into account. Moreover, the patients in the fentanyl and midazolam group, by chance, had a higher preprocedural level of anxiety and were, therefore, likely to show a greater decrease in anxiety level once the procedure was completed.

The authors of another study (10) showed a significant reduction in pain and anxiety experienced by patients who were trained in relaxation techniques and who then practiced relaxation exercises during lower limb angiography; however, only ionic contrast medium was used in that study. It has been shown (11) that high pain and anxiety scores reported by the patients undergoing arteriography have no influence on the administration of sedatives and analgesics but that the institution at which the procedure is performed does have such an influence.

We have shown that the overall level of pain experienced by patients undergoing diagnostic femoral arteriography was low and that 109 (87.2%) patients assigned pain ratings of "none" or "slight discomfort". This raises the question of what is acceptable pain and what threshold merits pharmacologic intervention. In a study by Lang and Berbaum (8) on the education of interventional radiology personnel in techniques of nonpharmacologic analgesia, patients recorded an "acceptable" pain score of 1.52 on a scale of 0 to 6. This would be roughly equivalent to a score of 2.27 on our five-point scale. Although we did not record an "acceptable" pain level, we believe that the scores given by our placebo group indicate that the minimal discomfort experienced was within levels tolerable to the patient. If the ultimate end point of whether a procedure is acceptable or not is readiness to undergo it again, then it would appear that the use of sedatives and analgesics is not routinely necessary in the majority of patients. When asked whether they would be willing to undergo the procedure again if their physician recommended that they do so, there were no differences between treatment groups. When a physician recommends a diagnostic procedure, almost all patients will agree to undergo that procedure; however, our question was designed to measure any reluctance by the patients to return for another test.

We have shown a significant reduction in discomfort reported by the patients who received midazolam and fentanyl. However, we contend that this reduction in discomfort is not justified by the attendant risks and costs. Although these drugs are widely used for many procedures, there inevitably is a risk associated with their use, especially in the elderly population of patients with atherosclerotic disease and associated cardiorespiratory compromise. By 1990, more than 80 deaths in the United States had been associated with the administration of midazolam to sedate patients undergoing various diagnostic or therapeutic medical and surgical procedures (12). The combination of fentanyl and midazolam causes hypoxemia, apnea, and hypotension (12,13). Analgesic doses of fentanyl can, in rare cases, cause chest wall rigidity, which may make ventilation difficult (5,14). To use these drugs safely, therefore, requires the attendance of a nurse or physician trained in the management of conscious sedation, whose only role in the angiographic suite is to monitor and manage the provision of the drugs (15,16). Therefore, important resource issues and implications are raised by the routine practice of administering sedatives and analgesics for lower extremity angiography (17); however, if sedatives and analgesics are to be readily available to every patient, when needed, these costs cannot be entirely negated.

Although we failed to demonstrate an advantage in patient comfort when midazolam is administered intravenously, it could be argued that its use alone (without fentanyl) is safer (12,18) and could, therefore, be a useful compromise. However, we found that patient compliance was reduced with the use of midazolam, largely owing to involuntary movement or the development of agitation in some older patients. Cragg et al (9) also found significantly less cooperation in patients who received midazolam alone as compared with the level of cooperation in patients who received both midazolam and fentanyl. Furthermore, a combination of midazolam and fentanyl provides greater anxiolysis than does midazolam alone (19).

Having argued against the widespread use of conscious sedation in all patients undergoing lower limb arteriography, it would be useful to identify any subgroups of patients who might benefit from its selective use. Patients who had previously undergone arteriography reported higher pain levels than did those who had not. This is contrary to the result that one might have anticipated, because familiarity might be expected to lessen the fear of the unknown and thereby reduce pain perception (20). Our finding is, however, consistent with other research: An increase in analgesia requirements has previously been reported (17) in a group of patients undergoing repeat interventional radiologic procedures. Results of another study (20) also suggest that there is no reduction in pain experienced when an individual repeatedly undergoes a certain procedure. Patients who have previously undergone an interventional procedure may, therefore, benefit from the application of conscious sedation.

The present study had limitations: It was a single-blind, prospective, randomized study, and local restrictions required that the radiologists and nurses not be blinded to the treatment arm, which could introduce bias into the radiologists’ and nurses’ assessments. In addition, patients in our placebo group were administered sham drugs, so the placebo effect of the procedure alone was not evaluated. Moreover, the sham injections were delivered as a single bolus and so did not mimic exactly the multiple injections delivered to patients who received the sedative and/or analgesic injections.

In summary, we demonstrated that lower limb arteriography is a relatively painless experience for most patients when modern radiologic techniques are used. Although the use of intravenous midazolam and fentanyl provided a reduction in discomfort to those undergoing the procedure, we believe that the associated cardiorespiratory compromise and increased use of resources negate this slight advantage to the patient. We advocate that routine intravenous administration of sedatives for aortofemoral arteriography should be reviewed; we recommend the use of sedatives for protracted procedures and in patients who have previously undergone arteriography.


   FOOTNOTES
 
Author contributions: Guarantor of integrity of entire study, P.T.K.; study concepts, I.M.G.K., P.T.K.; study design, P.T.K.; definition of intellectual content, P.T.K., I.M.G.K.; literature research, P.T.K.; clinical studies, P.T.K., C.S.B., W.C.L.; data acquisition, P.T.K., W.C.L., C.S.B.; data analysis, P.T.K.; statistical analysis, P.T.K.; manuscript preparation, P.T.K.; manuscript editing and review, all authors.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

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