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Department of Anesthesiology & Critical Care Medicine, The Childrens Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania
Address correspondence and reprint requests to Donna M. Rajchert, MD, Department of Anesthesiology & Critical Care Medicine, Childrens Hospital of Philadelphia, 9th Floor Main Bldg., 34th Street and Civic Center Boulevard, Philadelphia, PA 19104-4399. Address e-mail to rajchert{at}email.chop.edu
| Abstract |
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) and prior history of reactive airways disease (RR, 4.6; 95% CI, 1.514.3). In a case-control study, all cases of bronchospasm during induction of anesthesia in the 5-mo time period that rapacuronium was available for clinical use were identified. Aside from the 12 cases of bronchospasm with rapacuronium, 11 additional cases of bronchospasm were associated with the use of other muscle relaxants. Four controls were randomly selected for each of the 23 cases of bronchospasm. Children with bronchospasm during induction of anesthesia were several times more likely (odds ratio, 10.1; 95% CI, 3.528.8) for having received rapacuronium compared with other muscle relaxants. IMPLICATIONS: In a retrospective cohort study, significant risk factors for the development of bronchospasm with the administration of rapacuronium on induction of anesthesia included rapid sequence induction and prior history of reactive airways disease. In a case-control study, children with bronchospasm during induction of anesthesia were several times more likely to have received rapacuronium compared with other muscle relaxants.
| Introduction |
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Rapacuronium became available for clinical use at The Childrens Hospital of Philadelphia on March 1, 2000. Several severe cases of bronchospasm presented within the first few months of clinical use that appeared to be temporally related to the administration of rapacuronium prompted two related studies. All of these cases were reported to the Food and Drug Administration (FDA), and rapacuronium was withdrawn from the hospitals formulary on July 31, 2000 pending results of the studies. First, a retrospective cohort study was performed to determine which risk factors, if any, existed for the development of bronchospasm after the administration of rapacuronium. Second, a case-control study was designed to answer the question, "Are children with bronchospasm during induction of anesthesia more likely to have received rapacuronium compared with other muscle relaxants?"
| Methods |
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The timeframe for both the retrospective cohort and the case-control studies was limited to the period during which rapacuronium was available for clinical use (March 1, 2000 to July 31, 2000). For the retrospective cohort study, our intraoperative anesthesia record database was queried using the research module of the CompuRecord® system to identify all cases in which rapacuronium was administered to patients 018 yr old. Two independent reviewers inspected these records to determine which patients met the criteria for a diagnosis of bronchospasm during induction of anesthesia. Criteria for the diagnosis of bronchospasm during induction included either a statement in the narrative of the anesthesia record that the patient had developed bronchospasm or documentation of the use of a bronchodilator within 15 min after induction of anesthesia. The following data were abstracted from each anesthesia record: age, weight, sex, ASA physical status, history of reactive airways disease (RAD), history of drug allergy, rapacuronium dose (mg/kg), mode of induction of anesthesia (rapid or modified rapid sequence induction [RSI] versus routine inhaled or IV induction), IV induction drug (propofol versus thiopental), and use of morphine. Patients were considered to have prior RAD only if their ASA physical status was II or more and if at least one of the following items were documented in the preanesthetic evaluation or intraoperative anesthesia record: a) RAD was listed as a concomitant diagnosis or b) the patient was receiving at least one medication used for the treatment of RAD (e.g., inhaled or oral bronchodilators, inhaled steroids or cromolyn sodium).
In addition to the cases of bronchospasm during induction of anesthesia with rapacuronium identified in the retrospective cohort study, cases of bronchospasm during induction of anesthesia with other muscle relaxants were identified for the case-control study. First our intraoperative anesthesia record was queried using the research module for the standard comment "albuterol aerosol treatment." The CQI database was queried to find all cases of voluntarily reported bronchospasm during the study time frame. Two independent reviewers applied the same criteria as in the cohort study for identification of bronchospasm during induction of anesthesia. Four controls were identified for each case of bronchospasm. The controls were randomly selected from among the patients undergoing procedures on the same day as each case by matching the last digit of medical record number with a table of random digits. Patients were excluded from the Control group if an oral or nasal tracheal tube or tracheostomy tube was present before induction of anesthesia, if a muscle relaxant was not administered, or if the patient was >18 yr of age. Data abstracted from each anesthesia record were the same as those for the retrospective cohort study with the addition of the specific muscle relaxant administered. The criteria for determining a history of RAD were the same as that used for the retrospective cohort study.
The statistical approach was similar for both the retrospective cohort and the case-control studies. Univariate analyses were conducted using an unpaired Students t-test for parametric variables. Fishers exact test and relative risk (RR) (cohort study) or odds ratio (OR) (case-control study) calculated for categorical variables. The 95% CIs were calculated for both the RR and OR. A P value < 0.05 was considered significant as were RR or OR whose 95% CI excluded unity. The Kappa statistic was calculated to assess degree of agreement between the two reviewers.
| Results |
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for RSI). A definite history of the presence or absence of RAD was noted in the preoperative evaluation or intraoperative anesthesia record of 186 of the 287 patients who received rapacuronium. The remaining 101 patients were classified as not having RAD, giving an overall incidence of RAD of 23%. The RR of developing bronchospasm was significantly increased (RR, 4.6) for patients with a history of prior RAD (Table 2).
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| Discussion |
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We identified rapacuronium as a possible cause of bronchospasm in part because of the severity of several of the episodes and withdrew rapacuronium from clinical use at the end of July 2000. There have been case reports of severe bronchospasm temporally related to the administration of rapacuronium during the induction of anesthesia including reports of five deaths (6). In recent published reports, 14 of 21 patients had very severe bronchospasm after rapacuronium use (79). Descriptions of the events were laden with catastrophic phrases such as inability to ventilate, no chest wall movement, lack of detection of PETCO2 on capnography despite visual confirmation of the correct placement of the tracheal tube, and oxygen desaturation. Narrative comments in our anesthetic records were similar to those previously reported. (Table 1).
Bronchospasm has been reported with the use of many neuromuscular blocking drugs including succinylcholine, d-tubocurarine, atracurium, rocuronium, mivacurium, and rapacuronium (719). A 10.7% incidence of pulmonary side effects (bronchospasm and increased airway pressure) in patients receiving rapacuronium has been reported with only one case of bronchospasm described as a serious adverse experience (20). Another study reported a 14.7% incidence of bronchospasm with rapacuronium administration without any increases in plasma histamine levels (21). None of these patients was difficult to ventilate. We found that pediatric patients with bronchospasm during induction of anesthesia were 10 times more likely to have received rapacuronium than another neuromuscular blocking drug. We estimated the incidence of bronchospasm for patients receiving rapacuronium at 4.2%. The manufacturers estimated incidence in the package insert is 3.2%, which lies within the 95% CI of our estimate.
Many nondepolarizing drugs have been administered in larger than usual doses to speed onset of clinical effect (22). Because RSI was a risk factor for bronchospasm, it might have been expected that patients with bronchospasm would have received larger doses of rapacuronium. However, we found no difference in the dose of rapacuronium between patients who developed bronchospasm and those who did not. This suggests the possibility that the rapidity of drug administration during RSI rather than the magnitude of the dose may play a role in the development of bronchospasm.
Historically, the anesthesia record has been seen as a means of documenting the patients condition. Because the advent of the computerized anesthesia record has increased the ease of extracting and interpreting data, the role of the anesthesia record has expanded; it is now valuable as a research tool. However, research using the automated anesthesia recording system has not yet been systematically conducted in pediatrics, and we are aware of only two publications that have used these records to determine outcomes in anesthetized adults (23,24). This study shows the importance of a computerized anesthesia record for research, especially in investigating adverse events. It is extremely useful in conducting retrospective cohort and case-control studies. Although these observational studies cannot prove cause and effect, they can offer valuable information that cannot be obtained in a randomized clinical trial because of ethical or practical considerations. This may be particularly useful for identification of clinical problems that occur infrequently.
One of the major limitations of our study was the possibility that we did not capture all the reports of postinduction bronchospasm for patients who did not receive rapacuronium. In our computerized anesthesia record system there is a check box for a standard comment of albuterol aerosol treatment. Some of the anesthesiologists may have entered a narrative comment of the use of albuterol rather than checking the standard comment. Although our computerized anesthesia recording system allows for easy querying of common drugs and standardized comments, it does not allow us to query narrative comments in the body of the anesthesia record. We can be confident that our study captured all the patients who received rapacuronium because we examined the record of every patient who received this drug. However, we may not have captured all cases where bronchospasm occurred if another muscle relaxant was used. Unless the anesthesiologist voluntarily reported this complication to our CQI database, it would be irretrievable. Although voluntary reporting in CQI is not reliable for minor events that are not life-threatening, it is more likely that all severe cases will be reported (25). Although only 6 of the 12 cases of bronchospasm after the administration of rapacuronium were reported to the CQI database, these were the severe cases. A better design of the record and increased education of the users may resolve this problem.
The presence or absence of RAD could not be definitely determined for 35.2% of the retrospective cohort and 28.7% in the case-control subjects. However, we took the conservative approach by classifying all of these patients as not having a history of RAD. Despite this approach, the RR for a history of RAD was 4.6 (95% CI, 1.514.3) in the Bronchospasm group. If we assumed that the total incidence of RAD in the entire cohort was the same as the incidence in patients in whom a definite presence or absence of RAD history was established, the RR for RAD would be even larger at 5.6 (95% CI, 1.520.3).
In conclusion, this retrospective cohort study has determined that a history of RAD and the RSI were risk factors for the development of bronchospasm after induction of anesthesia and rapacuronium administration. In a case-control study we have determined that children with bronchospasm during induction of anesthesia were several times more likely to have received rapacuronium than other muscle relaxants.
| Footnotes |
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| References |
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