Sep 10, 2002 - cherry-flavored pentobarbital sodium (Nembutal) and oral chloral hydrate to sedate infants undergoing radiologic imaging. SUBJECTS AND ...
Comparison of Oral Pentobarbital Sodium (Nembutal) and Oral Chloral Hydrate for Sedation of Infants During Radiologic Imaging: Preliminary Results Veronica J. Rooks 1,2 Taylor Chung 1,3 Linda Connor1 David Zurakowski 4 Frederic A. Hoffer 1,5 Keira P. Mason 6 Patricia E. Burrows 1
Received July 11, 2002; accepted after revision September 10, 2002. 1 Department of Radiology, Children’s Hospital and Harvard Medical School, 300 Longwood Ave., Boston, MA 02115. Address correspondence to P. E. Burrows. 2
Present address: Department of Radiology, Walter Reed Army Medical Center, 6825 16th St. N. W., Washington, DC 20307-5001. 3
Present address: Edward B. Singleton Department of Diagnostic Imaging, Texas Children’s Hospital, Baylor College of Medicine, 6621 Fannin, Houston, TX 77030.
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Department of Biostatistics, Children’s Hospital, Harvard Medical School, Boston, MA 02115. 5 Present address: Department of Diagnostic Imaging, St. Jude Children’s Research Hospital, University of Tennessee, 332 N. Lauderdale St., Memphis, TN 38105. 6
Department of Anesthesia, Children’s Hospital, Harvard Medical School, Boston, MA 02115. AJR 2003;180:1125–1128 0361–803X/03/1804–1125 © American Roentgen Ray Society
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OBJECTIVE. The purpose of this study was to compare the safety and efficacy of oral cherry-flavored pentobarbital sodium (Nembutal) and oral chloral hydrate to sedate infants undergoing radiologic imaging. SUBJECTS AND METHODS. We prospectively recorded data for all infants sedated with oral cherry-flavored pentobarbital sodium and oral chloral hydrate for imaging examinations between January 1997 and August 1999. The parameters recorded were each patient’s age, weight, and American Society of Anesthesiologists classification; the time required to sedate; the total length of sedation time; the time required to discharge from the recovery room; and adverse events. The two-sample Student’s t test and Fisher’s exact test were used for statistical analysis. RESULTS. Oral pentobarbital sodium was administered to 317 infants. These infants had a mean age ± SD of 6.9 ± 3.1 months and a mean weight of 7.8 ± 4.8 kg; they received a median dose of 4 mg/kg of body weight. Oral chloral hydrate was administered to 358 infants. These infants had a mean age of 5.9 ± 3.3 months and a mean weight of 7.3 ± 4.9 kg; they received a median dose of 50 mg/kg of body weight. The mean time required to sedate was 19 ± 14 min for infants receiving oral pentobarbital sodium and 16 ± 11 min for infants receiving oral chloral hydrate ( p = 0.02); the mean time required to discharge was 100 ± 35 min for infants in the oral pentobarbital sodium group and 103 ± 36 min for infants in the oral chloral hydrate group ( p = 0.31); the mean length of sedation was 81 ± 34 min for the oral pentobarbital sodium group and 86 ± 36 min for the oral chloral hydrate group ( p = 0.07); and median American Society of Anesthesiologists classification for both groups was P1. Oral pentobarbital sodium was inadequate for sedation in one patient (0.3%) and chloral hydrate was inadequate for sedation in another (0.3%) ( p = 1.00). Adverse events were recorded for five patients (1.6%) in the oral pentobarbital sodium group and for six patients (1.7%) in the chloral hydrate group ( p = 0.99). CONCLUSION. Oral pentobarbital sodium is as safe and efficacious as oral chloral hydrate for sedating infants.
T
he increasing use of CT, MR imaging, and interventional radiology procedures has resulted in an increasing number of infants who require sedation while undergoing imaging procedures. Oral chloral hydrate has been used successfully for sedating infants undergoing imaging [1–7] but is often difficult to administer because of its bitter taste and the relatively large volume that must be used. IV pentobarbital sodium (Nembutal; Abbott Laboratories, North Chicago, IL) has also been reported to be a safe form of sedation [6, 8, 9]. A pilot study at our institution to assess patient tolerance and parent satisfaction found that there was more acceptance of cherry-flavored pentobarbital
sodium and that pentobarbital sodium provided efficacy and safety that were similar to those provided with chloral hydrate [10]. In the prospective study we report, we sought to further compare the safety and efficacy of oral cherry-flavored pentobarbital sodium and oral chloral hydrate for use in infants undergoing radiologic imaging.
Subjects and Methods After gaining institutional review board approval, we prospectively recorded data for infants sedated with either oral pentobarbital sodium or oral chloral hydrate in preparation for imaging examinations performed between January 1997 and
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Rooks et al. August 1999. Patients receiving additional medications for sedation or analgesia were not included in our study. Before sedation, each patient’s medical record was evaluated for contraindications to sedation, and a medical history for the infant was obtained from one of the parents, including current medications, previous sedation experience, allergies, and oral intake status. A physical status classification was assigned as defined by the American Society of Anesthesiologists (ASA) physical status classification system [11]. Only patients assigned ASA class P1 (a generally healthy patient) or P2 (a patient with mild systemic disease) were sedated. Infants who did not qualify for sedation under this classification system were referred to our institution’s anesthesiology department. After obtaining informed parental consent, we administered the sedation in accordance with the Children’s Hospital radiology department sedation committee’s established (1993) sedation guidelines, which are based on the guidelines of the American Academy of Pediatrics [12–18]. Sedation was administered by a registered nurse trained in pediatric life support, under the supervision of a radiologist with credentials for pediatric sedation. The sedation agent was drawn and mixed in a syringe and administered orally. No enteric tubes were used. Infants in the oral pentobarbital sodium group were given an initial dose of 4 mg/kg of body weight (50 mg/mL) that was mixed with cherry syrup and titrated accordingly, up to a maximum of 8 mg/kg of body weight. Additional doses were administered at 20-min intervals. Infants in the oral chloral hydrate group were given an initial dose of 50 mg/kg of body weight (100 mg/mL) that was titrated at 20-min intervals up to a maximum of 100 mg/kg of body weight. All children were monitored continuously with pulse oximetry. Heart rate and transcutaneous oxygen saturation level were recorded every 5 min during the procedure and every 15 min during recovery. “Blow-by” oxygen was routinely administered to the sedated patients as is required by sedation policy guidelines. Discharge criteria were those approved by the postanesthesia care unit. The parents of all patients were contacted by a member of the radiology nursing staff 24 hr after sedation. Parameters recorded included the patient’s age, weight, and ASA classification as well as the dose administered. Outcome parameters recorded by the radiology nursing staff included the time required to sedate (defined as the length of time required after the sedative administration to achieve adequate sedation), the time required to discharge (defined as the length of time from sedative administration to discharge from the recovery room), and the total time sedated (defined as the total length of time that the patient was sedated). The adverse events recorded included failed sedation (defined as the inability to complete the imaging examination or procedure); prolonged sedation (defined as sedation lasting > 3 hr); abnormal oxygen saturation level (defined as oxygen saturation ≤ 95% and recorded in degrees of mild [90–95%], moderate
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[85–89%], and severe [< 85%]); vomiting; wheezing; and unplanned admission to the hospital. Delayed events—such as vomiting, hyperactivity, irritability, or other symptoms that caused parental concerns—were also recorded. Follow-up of all complications was conducted by having a member of the radiology nursing team contact the parent of each patient within 24 hr after the patient received the sedative drug and having the radiology sedation committee review the sedation records. A power analysis revealed that a total sample size of 675 patients in the two groups—pentobarbital sodium ( n = 317) and chloral hydrate (n = 358)—would provide 84% power to detect a 3% difference in the adverse event rate on the basis of Fisher’s exact test. Outcome variables included the occurrence of sedation failure as well as adverse and delayed effects. Continuous data were tested for normality using the Kolmogorov-Smirnov test [19] and found to be normally distributed. Therefore, the groups were assessed using unpaired Student’s t tests. Analysis of covariance was used to compare the time required to sedate and the time required to discharge in order to adjust for differences in age and weight between the treatment groups. Fisher’s exact test was used to compare proportions for categorical data. Confidence limits (95%) were determined for the rates of adverse events. All reported p values were two-tailed; values of less than 0.05 were considered to be statistically significant. Statistical analysis was performed using the a statistical software package (SPSS version 11.0; SPSS, Chicago, IL).
Results
In total, 675 infants were sedated for MR imaging, CT, nuclear medicine, and interventional radiology procedures. Patient population data were similar for both groups (Table 1). Among the 317 patients sedated with oral pentobarbital sodium, 228 (72%) were sedated after receiving a dose of 4 mg/ kg of body weight, 76 (24%) required 6 mg/ kg, and 13 (4.1%) received 8 mg/kg. Among the 358 patients sedated with chloral hydrate, 297 (83%) received 50 mg/kg of body weight or less, 60 (16.8%) received 75 mg/ kg, and one (0.3%) required 100 mg/kg. The mean time required to sedate (± SD) was 19 ± 14 min for the oral pentobarbital sodium group and 16 ± 11 min for the oral chloral hydrate group ( p = 0.02); the mean time required to discharge was 100 ± 35 min for the oral pentobarbital sodium group and 103 ± 36 min for the oral chloral hydrate group ( p = 0.31); the mean length of sedation was 81 ± 34 min for the oral pentobarbital sodium group and 86 ± 36 min for the oral chloral hydrate group ( p = 0.07). Sedation was unsuccessful in one patient (0.3%) in the oral pentobarbital sodium group
and in one patient (0.3%) in the chloral hydrate group ( p = 1.00). Adverse events were recorded for five patients (1.6%) in the oral pentobarbital sodium group versus six patients (1.7%) in the chloral hydrate group ( p = 0.99). In the oral pentobarbital sodium group, the patient in whom sedation failed vomited immediately after administration of the second dose and remained alert. One patient who received 6 mg/kg experienced a prolonged sedation without additional complication and was discharged 5 hr after administration of the sedative. One inpatient who had a history of severe gastroesophageal reflux experienced a severe decrease in oxygen saturation level. This patient had a gastrojejunal feeding tube in place and had been allowed nothing by mouth for 12 hr. He had been given 4 mg/kg of pentobarbital sodium through the jejeunal port yet had an abnormal oxygen saturation level (84%) for 15 min, requiring suctioning and airway repositioning to regain normal oxygen saturation. After the patient was stabilized, imaging was completed. No patients in the oral pentobarbital sodium group had unplanned admissions to the hospital. However, one patient in this group, who had no preexisting respiratory condition, became stridorous with inspiratory and expiratory wheezing but responded well to one albuterol treatment and met the criteria required for discharge 2 hr after sedation. There was one paradoxical reaction among the children in the oral pentobarbital sodium group.
TABLE 1
Patient Data for 675 Infants Receiving Oral Pentobarbital Sodium or Oral Chloral Hydrate Patient Group
Patient Data
Reason for sedation MR imaging CT Nuclear medicine Interventional radiology Age (mo)a Weight (kg)a Median dose (mg/kg) Median ASA
Pentobarbital Chloral Sodium Hydrate (n = 317) (n = 358)
230 85 1 1 6.9 ± 3.1 7.8 ± 4.8 4 1
268 87 1 2 5.9 ± 3.3 7.3 ± 4.9 50 1
Note.—ASA = American Society of Anesthesiologists classification [11]. a Mean ± SD.
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Sedation of Infants During Radiologic Imaging One delayed event occurred in the oral pentobarbital sodium group. Four hours after discharge, a parent brought a patient to the emergency department, reporting perioral cyanosis in the infant. A physician did not observe this event, and the condition of the patient appeared normal during the 4-hr observation period in the emergency department. No delayed events occurred after 24 hr in the oral pentobarbital sodium group. Of the six patients in the chloral hydrate group with adverse events (1.7%), four patients experienced mildly decreased oxygen saturation levels. Two patients required airway repositioning to regain normal oxygen saturation. One patient with a recorded abnormal oxygen saturation of 91% required resuscitation with an Ambu bag (Medibag; Ambu International, Linthicum, MD), observation in the postanesthesia care unit, and an additional 24 hr of observation but had no further complications. One patient with a transient decrease in the oxygen saturation level (90%) for less than 20 min was observed for 24 hr without further complications. These two patients accounted for the two unplanned hospital admissions that occurred in the oral chloral hydrate group. Other adverse events in the chloral hydrate group included irritability and hyperactivity lasting approximately 30 min ( n = 1) and one episode of vomiting ( n = 1). No delayed events beyond 24 hr after administration of sedation occurred in the oral chloral hydrate group.
Discussion
Our study found no significant difference in the safety of the two oral sedatives. Adverse events occurred infrequently in both groups. The few adverse events that did occur were managed expeditiously and did not result in a poor outcome for any patient. The number of patients in the chloral hydrate group who experienced mild, self-limiting, transient hypoxia lasting less than 10 min is similar to the number reported in the literature [2]. We found no difference between the two agents with respect to the number of mild hypoxic events that were corrected with head positioning. One patient in the oral pentobarbital sodium group experienced a severe transient hypoxic event but responded to suctioning and repositioning. Because the patient had a history of gastroesophageal reflux, he probably should have been sedated with airway protection in place. One patient in the chloral hydrate group had a mildly abnormal oxygen satura-
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tion level; he required resuscitation and observation in the postanesthesia care unit but experienced no further adverse events. Wheezing developed in one patient who received oral pentobarbital sodium, but the wheezing resolved after treatment with an albuterol nebulizer. The patient had not been given contrast medium, was not ill before sedation, and had no known history of asthma. Therefore, the wheezing was likely caused by pentobarbital sodium; it is a known side effect of this drug. We find it interesting that only one of 317 patients experienced a paradoxical reaction to oral pentobarbital sodium, approximately one third of our previously reported incidence using IV pentobarbital [20]. Vomiting occurred in a small number of infants in both groups, usually after reintroduction of oral intake. No patients vomited while sedated. The two sedation agents were also similar in efficacy; the success rate of 99% was similar to or better than the results reported in the literature for chloral hydrate [2, 3, 5, 7]. The mean time required to sedate was slightly longer (3 min) with oral pentobarbital sodium than with oral chloral hydrate. However, the mean length of time sedated and the mean time required to discharge were slightly shorter (5 min and 3 min, respectively) than with chloral hydrate. Differences in time required to achieve sedation and discharge may affect the efficient use of imaging facilities and nursing care. Palatability of oral medication is relatively important in the care of infants and young children. Infants frequently resist taking badtasting liquids and may expel the drug or cough and potentially aspirate it. This behavior makes accurate dosing impossible, leading to potential underdosing or overdosing. It also adds to the stress experienced by the patient, parents, and nursing staff. After the completion of our study, a 19month-old boy who received 8 mg/kg of oral pentobarbital sodium in our institution died at home approximately 12 hr after administration of the drug. The patient had not become sedated during the 2 hr that he was monitored after administration of the drug and was awake at discharge from the imaging unit. Because the patient had underlying medical conditions (Down syndrome and a severe seizure disorder), an autopsy was not performed. The available medical records were reviewed thoroughly after the event, but no conclusion concerning the cause of death was reached.
Although the role of oral pentobarbital in this patient’s death is not clear, the incident has resulted in increased concern about the potentially inconsistent nature of gastric absorption of drugs. Published experimental data in animals and healthy humans have shown that orally administered pentobarbital sodium is usually completely absorbed within 1 hr of ingestion [21, 22]. A review of departmental sedation data collected since our study was completed found no additional cases of severe adverse events in patients given oral pentobarbital sodium sedation. Therefore, our institution has decided to continue the use of oral pentobarbital sodium for sedation of infants younger than 1 year who are undergoing painless imaging procedures. Patients receiving oral sedation in our department are scheduled to undergo imaging in the morning to provide a relatively long time during which the patient can be monitored in the hospital or observed by parents at home. In conclusion, oral pentobarbital sodium flavored with cherry syrup is as safe and as effective as oral chloral hydrate for sedation of infants undergoing painless imaging procedures. Because it is more palatable than chloral hydrate, oral pentobarbital sodium may be the agent of choice for infants. Further studies involving larger numbers of patients are necessary to confirm the safety of this sedation regimen.
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