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Use of Intravenous Methohexital as a Sedative in Pediatric Emergency Departments
Hanan Sedik, MD
Arch Pediatr Adolesc Med. 2001;155:665-668.
ABSTRACT
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Objective To evaluate the effectiveness and safety of intravenous methohexital
as a sedative in children undergoing emergency computed tomographic scans.
Design Case series.
Setting An urban pediatric emergency department at a level I trauma center.
Participants Patients receiving intravenous methohexital for sedation to undergo
emergency computed tomographic scans.
Methods Descriptive data were generated, including demographics, doses administered,
times of sedation, outcomes, and complications.
Results Data are reported from a total of 55 patients. The doses administered
ranged from 0.5 mg/kg to 2.0 mg/kg (mean ± SD, 1 ± 0.5 mg/kg).
Onset of sedation was rapid (mean ± SD, 1 ± 0.4 minutes), sedation
was brief (mean ± SD, 12 ± 5 minutes), and the mean ±
SD length of the drug's effects was 14 ± 6 minutes. Sedation was effective
in most cases, and only a few patients had complications.
Conclusion Intravenous methohexital is a short-acting and effective sedative for
use in pediatric emergency departments to obtain computed tomographic scans.
INTRODUCTION
COMPUTED tomographic (CT) scans are frequently performed on an emergent
basis in pediatric emergency departments (PEDs). Infants and young children
often require sedation for CT scans to be completed successfully. The duration
of CT scans may vary from 5 to 30 minutes, depending on the type of scan and
the need for additional imaging. Different classes of medications have been
used to achieve sedation in children for this purpose. These include chloral
hydrate (both orally and rectally), barbiturates such as pentobarbital, benzodiazepines
such as midazolam, and narcotics like meperidine (alone or in combination
with promethazine) and chlorpromazine.1, 2, 3, 4, 5, 6, 7, 8, 9
Most of these medications have long induction and recovery times that extend
patients' length of stay in the emergency department.
Methohexital is an ultrashort-acting barbiturate, producing few cumulative
adverse effects and a more rapid recovery than other barbiturates.10, 11, 12, 13 Because
of its quick onset, predictable physiological effects, minimal complication
rate, and short duration of action, methohexital may be an attractive option
for sedation in children. Rapid induction and speed of recovery make it ideal
in situations where a brief effect is desired, such as CT scans. Although
in our institution intravenous (IV) methohexital has been used as a sedative
to obtain CT scans, data in the literature remain sparse about its use in
PEDs.
The objective of this study was to evaluate the effectiveness and safety
of IV methohexital in achieving sedation in pediatric patients undergoing
emergency CT scans, and to document our experience with the use of methohexital
in our PED.
PATIENTS AND METHODS
We conducted this study in 2 phases. In phase 1, we retrospectively
reviewed medical records of patients in whom IV methohexital had been used
to achieve sedation to obtain CT scans. In phase 2, we prospectively studied
the use of IV methohexital to achieve sedation for the same procedure.
PHASE 1
After approval from our institutional review board, we reviewed medical
records of 653 children younger than 6 years who came to our PED between January
1990 and February 1998 and required CT scans. Of those, 35 patients were identified
in whom IV methohexital was used to achieve sedation. From these records,
we collected data on demographics, type of CT scan done, dose of methohexital
given, and complications.
PHASE 2
Between March 1998 and September 1998, all patients who came to our
PED requiring emergency CT scans and falling into the age group that might
require sedation were invited to participate in the study. Inclusion criteria
were patients meeting the American Society of Anesthesiologists class 1 or
2 criteria, parental consent, and the need for sedation to undergo the CT
scan. Exclusion criteria were abnormalities of the airway or the cardiorespiratory
system, a history of hypersensitivity to barbiturates, and patients who received
any sedatives or hypnotics within 6 hours of the CT scan. All patients had
existing IV lines for reasons other than the purpose of the study.
The institutional review board approved the research protocol, study
design, and consent forms. We followed guidelines published by the American
Academy of Pediatrics for monitoring patients during and after sedation for
diagnostic and therapeutic procedures.14 Sedation
flow sheets were created documenting patients' demographics, type of scan,
and presedation vital signs (including heart rate, respiratory rate, blood
pressure, and pulse oximetry).
While the patient was on the CT scan table, 1% methohexital sodium solution
was administered through a standard IV catheter followed by a 3-mL saline
flush. At the principal investigator's discretion, doses were titrated to
achieve sedation, marked by an adequate state of motionlessness that allowed
the start and completion of the scan. The initial dose was 0.5 mg/kg, titrated
up using increments of 0.5 mg/kg to a maximal dose of 2.0 mg/kg. No additional
sedatives were used.
Documentation of the dose of methohexital and times of administration,
onset of sedation (marked by motionlessness without stimulation), start of
scan, end of scan, end of sedation (marked by patients either starting to
move or cry, simultaneously or on stimulation), and return to a presedation
state (marked by return of vital signs and mental status) were all reported
on the sedation flow sheets.
Subjects were monitored continuously throughout the procedure by the
principal investigator and an accompanying nurse. Documentation of vital signs
included heart rate; respiratory rate and pulse oximetry were done at 1- to
2-minute intervals throughout the procedure. Presedation and postsedation
blood pressure was included in the documented vital signs. Complications and
interventions were also documented. In case of sedation failure, IV ketamine
was used to achieve conscious sedation to obtain the CT scans. The criterion
for discontinuation of monitoring was a return to a presedation level of consciousness.
STATISTICAL ANALYSIS
The primary end points were the percentage of patients who remained
motionless throughout their CT scans, as a measure of effectiveness of the
medication, and percentage of patients experiencing complications, as a measure
of drug safety.
Descriptive statistics were generated, including percentage distributions,
means, and SDs where appropriate. Data from phases 1 and 2 were examined separately
and then compared for differences between the 2 groups using the  2 test, t test, and Kruskal-Wallis test where
appropriate. Analysis was performed using Stata 6.0 (Stata Corp, College Station,
Tex) and SAS 6.12 (SAS Institute Inc, Cary, NC) statistical software.
RESULTS
There were a total of 55 patients, 35 in phase 1 and 20 in phase 2.
Twenty-two sedations were performed in phase 2 because 2 patients required
additional scans. There was no statistical difference between patients in
phase 1 compared with those in phase 2 in regard to age, weight, race, scan
type, total dose given, and dose in mg/kg (P >.05
for all), although there were more boys in phase 2 (85% vs 43%, P = .002).
In phase 1, the mean ± SD patient age was 28 ± 24 months,
and 43% were boys. The mean ± SD weight was 16 ± 13 kg. Of the
CT scans performed, 80% were for the head, 9% were for the abdomen, and 11%
were both head and abdominal. The mean ± SD dose of methohexital given
was 1 ± 0.4 mg/kg, and the mean ± SD total dose was 20 ±
18 mg/kg. There were no data on dose titration in phase 1 patients. All 35
patients remained motionless for the CT scans to be completed. No complications
were reported, and no interventions were needed.
In phase 2, the mean ± SD patient age was 26 ± 17 months,
and 85% were boys. The mean ± SD weight was 12 ± 4 kg, and 91%
of the CT scans performed were for the head. The mean ± SD dose of
methohexital given was 1 ± 0.5 mg/kg, and the mean ± SD total
dose was 14 ± 7.5 mg/kg.
For patients in phase 2, where prospective design allowed more data
collection, the mean onset of sedation was 1 minute, and the mean adequate
sedation time was 12 minutes. Although the mean scan time was 9 minutes, the
mean total procedure time was 15 minutes, as demonstrated in Table 1.
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Times of Sedations in Phase 2 of the Study*
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Only 2 patients (<1%) failed to be sedated, whereas the remaining
20 patients remained motionless for the CT scans to be completed. Three patients
(<1%) had a transient drop in their pulse oximetry that ranged from 93%
to 94% on room air, and were counted as complications. Those patients required
only a chin lift maneuver to bring their pulse oximetry to a value higher
than 95%, and remained stable throughout the procedure. No other complications
were observed.
COMMENT
Methohexital use as an induction agent has been well documented in the
anesthesia literature. Its use in children for induction of anesthesia has
been demonstrated via the rectal, intramuscular, and IV routes.15, 16, 17, 18
The pharmacokinetics of methohexital have been studied in humans, particularly
in children.19, 20
Methohexital has been used in adult emergency departments and has been
found to produce rapid and brief sedation, especially for orthopedic procedures.
Lerman et al21 studied 76 adult patients in
a prospective observational study where IV methohexital had been used for
a variety of procedures, and concluded that it caused clinically insignificant
changes in hemodynamics and oxygenation. Although respiratory depression did
occur, if significant it was brief and easily managed. Zink et al22 reported a consecutive case series of 102 patients
(including 10 patients younger than 10 years) who received IV methohexital
for various procedures. The authors concluded that methohexital is safe and
effective in selected emergency department patients.
Despite the popularity of methohexital in adult emergency departments,
its use in PEDs is rare. In a recent survey to all members of the emergency
medicine section of the American Academy of Pediatrics by Conners et al,23 less than 1% of respondents used methohexital (unmentioned
route of administration) to sedate uncooperative stable children for posttraumatic
head CT scans. Most of those respondents were board certified in pediatrics
and pediatric emergency medicine.
The use of methohexital via the rectal and intramuscular routes in children
undergoing imaging procedures has been documented in 3 published studies.
Manuli and Davies24 demonstrated its effectiveness
via the rectal route compared with oral chloral hydrate in a series of 190
patients undergoing CT scans and magnetic resonance imaging, and no cardiorespiratory
complications or allergic reactions occurred. Varner et al25
demonstrated methohexital use via the intramuscular route, comparing 3.5%
to 5% solution in achieving sedation for CT scans in a series of 50 pediatric
patients, and concluded that intramuscular methohexital is safe, effective,
and short acting. The use of rectal methohexital as a sedative for CT scans
of stable PED patients has been documented in a recent study by Pomeranz et
al.26
In our case series, we looked at IV methohexital in doses of 0.5 mg/kg
to 2.0 mg/kg to achieve sedation in pediatric patients for obtaining emergency
CT scans during their stay in the PED. Our primary measure was its effectiveness
in keeping patients motionless to obtain CT scans; most of the scans were
completed, signifying adequate sedation. The other measure was safety, and
only 3 of our patients had a small drop in their oxygen saturation, which
was transient and easily handled by the chin lift maneuver with no supplemental
oxygen.
In phase 2 of our study, we achieved rapid and brief sedation. The mean
onset of sedation after administering the drug was 1 minute; therefore, we
recommend that methohexital be given while the patient is on the CT scan table
and the radiology technician is ready to start the scan. The shortest adequate
sedation was 5 minutes, which is usually long enough to complete a noncontrast
head CT scan, whereas the longest adequate sedation was 21 minutes, enough
time to complete most abdominal CT scans. This rapid induction and recovery
help to expedite the process of discharging patients from the PED.
To our knowledge, our case series is exclusive in documenting the use
and effectiveness of IV methohexital in sedating children for CT scans during
their stay in the PED; however, it is limited by the number of sedations performed.
We documented a drop in oxygen saturation in only 3 of 55 patients. Although
this complication was transient and easily managed, our study had too few
patients to have detected rarer adverse effects of IV methohexital.
In summary, we conclude that IV methohexital produces rapid and effective
sedation, and we recommend its use as a sedative in PEDs for brief, nonpainful
procedures such as CT scans. We recommend further studies using IV methohexital
with larger numbers of patients for monitoring rare adverse effects. Studies
comparing IV methohexital with other sedatives in the PED are also recommended.
AUTHOR INFORMATION
Accepted for publication January 25, 2001.
The abstract was presented at the joint meeting of the Pediatric Academic
Societies and the American Academy of Pediatrics, "Advancing Children's Health
2000," Boston, Mass, May 13, 2000.
We thank Sunday Clark, MPH, for her help with the statistical analysis,
and Carlos A. Camargo, MD, DrPH, for his helpful comments on the manuscript.
From the Division of Pediatric Emergency Medicine, Henry Ford Hospital,
Detroit, Mich. Hanan Sedik, MD, is now at the Division of Pediatric Emergency
Medicine, Boston Medical Center, and at the Department of Pediatrics, Boston
University School of Medicine, Boston, Mass.
Corresponding author and reprints: Hanan Sedik, MD, Division of Pediatric
Emergency Medicine, Boston Medical Center, 91 E Concord St, Maternity 6, Boston,
MA 02169 (e-mail: Hanan.Sedik{at}bmc.org).
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ABSTRACT
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