© 2004 Lippincott Williams & Wilkins, Inc.
Volume 20(12) December 2004 pp 805-807
The Effect of Fasting Practice on Sedation With Chloral Hydrate
Keidan, Ilan MD*; Gozal, David MD†; Minuskin, Tal MD‡; Weinberg, Margalit RN, BA*; Barkaly, Haviva RN†;
Augarten, Arie MD‡
*Pediatric Anesthesia Unit, Sheba Medical Center, Tel Hashomer; †Department of Anesthesia and Intensive Care, Hadassah
Medical Center, Jerusalem and ‡Department of Pediatric Emergency Medicine, Sheba Medical Center, Tel Hashomer, affiliated to
the Sackler School of Medicine, Tel Aviv University, Israel.
Address correspondence and reprint requests to Arie Augarten, MD, Department of Pediatric Emergency Medicine, Sheba Medical
Center, Tel Hashomer, Ramat-Gan, Israel 52621. E-mail: email@example.com.
G Table 1
G Table 2
G Table 3
Objectives: Infants undergo various painless imaging procedures frequently. Mild sedation is required in such
cases to reduce anxiety as well as to ensure optimal performance of the procedure. The most frequently used
sedative as a single drug is chloral hydrate. The issue of preprocedural fasting is a subject of contention. The
purpose of this study was to assess the effect of the American Academy of Pediatrics (AAP)/American Society of
Anesthesiology (ASA) fasting practice guidelines on the efficacy and success of the sedation with chloral hydrate.
Methods: The sedation records of 200 infants from 2 hospitals who underwent auditory brainstem response for
evaluation of hearing loss were evaluated retrospectively. In the first hospital (group A), strict nulla per os (NPO)
guidelines were followed in accordance with the guidelines published by the AAP/ASA, whereas in the second
hospital (group B), no fasting period was required. All children were premedicated with chloral hydrate. We
evaluated the sedation failure rate, total dose of chloral hydrate needed, adverse effects, overall sleep time, and
time to discharge.
Results: The average fasting period as expected was significantly longer in group A patients than in group B
patients (5.7 ± 1.7 vs. 2 ± 0.2 hours; P < 0.001). Group A patients demonstrated a significantly higher failure rate
to achieve sedation with the first dose of chloral hydrate compared with group B patients (21% vs.11%; P = 0.03),
hence needing higher doses (83 ± 31 vs. 61 ± 21 mg/kg; P < 0.01), and were sedated for longer periods (103 ± 42
vs. 73 ± 48 minutes; P < 0.001) and discharged later. No difference was found in the adverse effect rate.
Conclusion: Fasting was associated with an increased failure rate of the initial sedation. As a consequence, an
increased total dose of chloral hydrate was required inducing a prolonged sedation time. Presumably, this is a
result of the fact that a hungry child is irritable and therefore more difficult to sedate.
Chloral hydrate is widely used in children to induce sedation during painless imaging procedures.
Preprocedural fasting has recently been an issue of concern. Stringent fasting guidelines promulgated by
the American Society of Anesthesiology (ASA)1,2 have been extended outside the operating room to
include procedural sedation, and was adopted by the American Academy of Pediatrics (AAP).3,4 AAP/
ASA guidelines rely on expert opinion and consensus. The literature, however, does not provide sufficient
evidence to test the hypothesis that preprocedure fasting results in a decreased incidence of adverse
outcomes among patients undergoing either moderate or deep sedation.5
In the emergency department, most procedures are not scheduled and fasting is unusual. It is common
practice in many children's hospitals to have no prerequisite for any fasting period prior to the
administration of chloral hydrate. The aim of this study was to evaluate the effects of fasting prior to
sedation with chloral hydrate. To accomplish this goal, a retrospective study was conducted involving
children who underwent auditory brainstem response (ABR) studies performed for hearing evaluation.
The study was held in 2 children's hospitals, one that adheres to AAP/ASA guidelines and one that does
This retrospective study was conducted in 2 large, urban hospitals in Israel: Hadassah Medical Center,
Jerusalem and Sheba Medical Center, Tel Hashomer. The study population consisted of 200 infants who
underwent ABR examination and were sedated with chloral hydrate (the first 100 subjects were sedated
during the year 2002 in each hospital). Patients were grouped according to the preprocedural fasting
policy. Group A (NPO group)-Hadassah Medical Center, where the guidelines published by the AAP/
ASA (avoiding solid food or formula for 6 hours, breast milk for 4 hours, or clear liquids for 2 hours)
were strictly adhered to. Group B-Sheba Medical Center, where no fasting period was required and the
parents were encouraged to feed their child just prior to their arrival to the audiology laboratory. The
sedation protocol followed in both hospitals allowed only the sedation of children with ASA physical
status I and II, and former preterm infants with a postconceptual age over 60 weeks. In both hospitals, the
sedation methodology and environment as well as hearing test technique and equipment were similar. All
children were sedated under the supervision of a qualified sedation nurse and were closely monitored in
accordance with the guidelines suggested by the AAP.4 The only medication given was chloral hydrate in
a dose range of 50 to 60 mg/kg of body weight. A second dose of chloral hydrate in the amount of 25 to
30 mg/kg of body weight was repeated if the first dose did not sedate the child successfully (within 30 to
45 minutes of the first dose).
The following information was extracted from the patients' sedation charts: demographic data, timing and
dose of chloral hydrate administration, ABR test starting and ending time, time of sleep and discharge.
The following adverse effects were recorded: desaturation (pulse oximetry <94% in room air), apnea,
irritability, failure to complete the test or nausea or vomiting. The need for a second dose and the dose
given was also recorded. Two-tailed Student t test, [chi]2, and Fisher exact tests were used for statistical
comparisons. Results were considered statistically significant for a P value <0.05.
The demographics of the children in the two groups were comparable (Table 1). Twenty-one percent and
11% of patients, in groups A and B, respectively, failed to be adequately sedated with the first dose of
chloral hydrate (P = 0.05). Most children, however, responded adequately to a second dose of chloral
hydrate, thereby allowing successful completion of the ABR study in the vast majority of cases. The
overall dose of chloral hydrate given to children in group A was significantly higher than that
administered to children in group B. The average sedation time and time to discharge were significantly
longer among the children in group A (Table 2). The number of children who spent more than 2 hours
sedated was significantly higher in group A as well (Table 3).
TABLE 1. Patient Demographics
TABLE 2. Comparison of Chloral Hydrate Dose and Effects between Groups
TABLE 3. Adverse Effects
There were no statistically significant differences in the incidence of adverse effects in either group.
Adverse effects noted included brief desaturation recorded in 4 children (1 in group B and 3 in group A).
The desaturations were transient in all cases and responded to head positioning and supplemental oxygen.
Agitation was noted in 2 children in group B who failed to complete the test (Table 3). No signs of
excessive nausea, vomiting, or aspiration were observed.
In most infants and small children undergoing hearing evaluation, as well as other painless procedures,
sedation is mandatory to allow satisfactory examination and meaningful results, free of artifacts created
by movement or crying. In most cases, only a mild to moderate sedative state is necessary, allowing the
reflexes protecting the airway to remain active. The ASA believes that fasting is still mandatory as a shift
on the sedation continuum toward deep sedation and the loss of protective airways reflexes is not always
In the present study, we found that patients who fasted prior to sedation with chloral hydrate had a
significantly higher sedation failure rate, needed higher doses of chloral hydrate and, consequently, were
sedated for longer periods compared with infants who were fed prior thereto. Several studies assessed the
relationship between fasting status and adverse events in pediatric patients undergoing procedural
sedation. Agrawal et al 6 found no difference between patients who had and had not fasted from among a
group of 905 children who underwent procedural sedation in the emergency department, as far as airway
complications, emesis, or other adverse events. Kennedy et al 7 found no association between the duration
of fasting and the occurrence of emesis in 260 patients who were sedated for orthopedic procedures.
Ghaffar et al 8 did not find any significant difference in the emesis rate between patients who fasted for
less than 2 hours and those who fasted for more than 2 hours prior to sedation for an echocardiogram.
Hoffman et al 5 tested the hypothesis that the application of an AAP/ASA-structured model would reduce
the risk of sedation-related adverse events. They found that adherence to fasting guidelines did not affect
the overall risk of complications. Interestingly, both Ghaffar et al 8 and Hoffman et al 5 found that the
occurrence of sedation failure was significantly higher among patients who fasted. These findings are
similar to ours and suggest that the higher sedation failure rate is due to the added difficulty in sedating a
In view of all the aforementioned, the AAP/ASA NPO guidelines for sedation are not evidence-based, and
their application is not always practical in the emergency department. An empty stomach in accordance
with these guidelines is recommended to prevent pulmonary aspiration, which is a rare event (an
estimation of 1 in 4500 elective procedures 9). On the other hand, implementation of these guidelines, as
shown above, involves the administration of higher doses of sedatives and, consequently, a prolonged
sedation time. These factors can affect the potency of protective airway reflexes and increase the
incidence of pulmonary aspiration.
However, the very low incidence of pulmonary aspiration and the small number of patients participating
in our study preclude us from commenting on the safety of sedation without following NPO guidelines.
An extremely large database will be required to detect differences in the incidence of such an uncommon
event in different fasting policies.
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Key Words: procedural sedation; chloral hydrate; fasting; auditory brainstem response (ABR) Download full-text
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