Sedation in children undergoing CT scan or MRI: effect of time-course and tolerance of rectal chloral hydrate

Efficacy of Rectal Versus Oral Chloral Hydrate in Pediatric Auditory Brainstem Response: Randomized Controlled Trial

Objective

To compare sedation success rates between rectal (RCH) and oral chloral hydrate (OCH) administration in children undergoing auditory brainstem response (ABR) testing and assess the incidence of adverse effects.

Study Design

Randomized controlled trial, performed between May 2023 and August 2023.

Setting

Ear, Nose, and Throat Outpatient Department at tertiary care hospital.

Methods

Pediatric patients aged 1 to 5 years, who were indicated for ABR testing were enrolled and randomly divided into 2 groups. The control group received 10% wt/vol chloral hydrate orally at a dose of 50 mg/kg, while the other group received the same dose through rectal administration. Onset of sedation, duration of sedation, recovery time, vital signs, and adverse effects were recorded and analyzed to assess sedative effectiveness and safety.

Results

Eighty-eight children were randomly assigned to RCH or OCH administration groups, the sedation success rates of RCH and OCH groups were 84.09% and 90.91%, respectively (P = .33). Adverse effects were detected in 11 children (12.5%), with a vomiting rate of 20.45% in the oral group versus 0% in the rectal group (P = .002). The diarrhea rate was 4.55% in the rectal group versus 0% in the oral group (P = .16). In either group, no serious adverse effects were documented.

Conclusion

RCH and OCH are both safe and effective for short-term sedation in pediatric patients during ABR testing. Interestingly, RCH administration offers a high success rate without vomiting or major adverse effects. This study established the effectiveness of RCH for sedation in children under specialized supervision.

Physiologically based pharmacokinetic/pharmacodynamic modeling to evaluate the absorption of midazolam rectal gel

OBJECTIVE

We aimed to 1) develop physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) models of a novel midazolam rectal gel in healthy adults, 2) assess the contribution of different physiologically relevant factors in rectal absorption, and 3) to provide supports for future clinical studies of midazolam rectal gel.

METHODS

We developed the rectal PBPK model after built the intravenous and the oral PBPK model. Then, the physiological progress of rectal route was described in terms of the drug release, the rectal absorption and the particle first-pass elimination. Next, the validated PBPK model was combined with the sigmoid E_max PD model. This PBPK/PD model was used to identify the dose range and the critical parameters to ensure safety sedation.

RESULTS

Based on the simulations, the recommended maximum dose for adults' sedation was 15 mg. And the retention time of midazolam rectal gel should be longer than 3 h to reach over 80% pharmacokinetics and pharmacodynamics effects.

CONCLUSION

We successfully developed a PBPK/PD model for the midazolam rectal gel, which accurately described the PK/PD behavior in healthy adults and indicated the transit time of rectum was the most sensitive parameter for absorption. This PBPK/PD model would be expected to support the future clinical studies and pediatric application.

Chloral hydrate as a sedating agent for neurodiagnostic procedures in children

BACKGROUND

This is an updated version of a Cochrane Review published in 2017. Paediatric neurodiagnostic investigations, including brain neuroimaging and electroencephalography (EEG), play an important role in the assessment of neurodevelopmental disorders. The use of an appropriate sedative agent is important to ensure the successful completion of the neurodiagnostic procedures, particularly in children, who are usually unable to remain still throughout the procedure.

OBJECTIVES

To assess the effectiveness and adverse effects of chloral hydrate as a sedative agent for non-invasive neurodiagnostic procedures in children.

SEARCH METHODS

We searched the following databases on 14 May 2020, with no language restrictions: the Cochrane Register of Studies (CRS Web) and MEDLINE (Ovid, 1946 to 12 May 2020). CRS Web includes randomised or quasi-randomised controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, the Cochrane Central Register of Controlled Trials (CENTRAL), and the specialised registers of Cochrane Review Groups including Cochrane Epilepsy.

SELECTION CRITERIA

Randomised controlled trials that assessed chloral hydrate agent against other sedative agent(s), non-drug agent(s), or placebo.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated studies identified by the search for their eligibility, extracted data, and assessed risk of bias. Results were expressed in terms of risk ratio (RR) for dichotomous data and mean difference (MD) for continuous data, with 95% confidence intervals (CIs).

MAIN RESULTS

We included 16 studies with a total of 2922 children. The methodological quality of the included studies was mixed. Blinding of the participants and personnel was not achieved in most of the included studies, and three of the 16 studies were at high risk of bias for selective reporting. Evaluation of the efficacy of the sedative agents was also underpowered, with all the comparisons performed in small studies. Fewer children who received oral chloral hydrate had sedation failure compared with oral promethazine (RR 0.11, 95% CI 0.01 to 0.82; 1 study; moderate-certainty evidence). More children who received oral chloral hydrate had sedation failure after one dose compared to intravenous pentobarbital (RR 4.33, 95% CI 1.35 to 13.89; 1 study; low-certainty evidence), but there was no clear difference after two doses (RR 3.00, 95% CI 0.33 to 27.46; 1 study; very low-certainty evidence). Children with oral chloral hydrate had more sedation failure compared with rectal sodium thiopental (RR 1.33, 95% CI 0.60 to 2.96; 1 study; moderate-certainty evidence) and music therapy (RR 17.00, 95% CI 2.37 to 122.14; 1 study; very low-certainty evidence). Sedation failure rates were similar between groups for comparisons with oral dexmedetomidine, oral hydroxyzine hydrochloride, oral midazolam and oral clonidine. Children who received oral chloral hydrate had a shorter time to adequate sedation compared with those who received oral dexmedetomidine (MD -3.86, 95% CI -5.12 to -2.6; 1 study), oral hydroxyzine hydrochloride (MD -7.5, 95% CI -7.85 to -7.15; 1 study), oral promethazine (MD -12.11, 95% CI -18.48 to -5.74; 1 study) (moderate-certainty evidence for three aforementioned outcomes), rectal midazolam (MD -95.70, 95% CI -114.51 to -76.89; 1 study), and oral clonidine (MD -37.48, 95% CI -55.97 to -18.99; 1 study) (low-certainty evidence for two aforementioned outcomes). However, children with oral chloral hydrate took longer to achieve adequate sedation when compared with intravenous pentobarbital (MD 19, 95% CI 16.61 to 21.39; 1 study; low-certainty evidence), intranasal midazolam (MD 12.83, 95% CI 7.22 to 18.44; 1 study; moderate-certainty evidence), and intranasal dexmedetomidine (MD 2.80, 95% CI 0.77 to 4.83; 1 study, moderate-certainty evidence). Children who received oral chloral hydrate appeared significantly less likely to complete neurodiagnostic procedure with child awakening when compared with rectal sodium thiopental (RR 0.95, 95% CI 0.83 to 1.09; 1 study; moderate-certainty evidence). Chloral hydrate was associated with a higher risk of the following adverse events: desaturation versus rectal sodium thiopental (RR 5.00, 95% 0.24 to 102.30; 1 study), unsteadiness versus intranasal dexmedetomidine (MD 10.21, 95% CI 0.58 to 178.52; 1 study), vomiting versus intranasal dexmedetomidine (MD 10.59, 95% CI 0.61 to 185.45; 1 study) (low-certainty evidence for aforementioned three outcomes), and crying during administration of sedation versus intranasal dexmedetomidine (MD 1.39, 95% CI 1.08 to 1.80; 1 study, moderate-certainty evidence). Chloral hydrate was associated with a lower risk of the following: diarrhoea compared with rectal sodium thiopental (RR 0.04, 95% CI 0.00 to 0.72; 1 study), lower mean diastolic blood pressure compared with sodium thiopental (MD 7.40, 95% CI 5.11 to 9.69; 1 study), drowsiness compared with oral clonidine (RR 0.44, 95% CI 0.30 to 0.64; 1 study), vertigo compared with oral clonidine (RR 0.15, 95% CI 0.01 to 2.79; 1 study) (moderate-certainty evidence for aforementioned four outcomes), and bradycardia compared with intranasal dexmedetomidine (MD 0.17, 95% CI 0.05 to 0.59; 1 study; high-certainty evidence). No other adverse events were significantly associated with chloral hydrate, although there was an increased risk of combined adverse events overall (RR 7.66, 95% CI 1.78 to 32.91; 1 study; low-certainty evidence).

AUTHORS' CONCLUSIONS

The certainty of evidence for the comparisons of oral chloral hydrate against several other methods of sedation was variable. Oral chloral hydrate appears to have a lower sedation failure rate when compared with oral promethazine. Sedation failure was similar between groups for other comparisons such as oral dexmedetomidine, oral hydroxyzine hydrochloride, and oral midazolam. Oral chloral hydrate had a higher sedation failure rate when compared with intravenous pentobarbital, rectal sodium thiopental, and music therapy. Chloral hydrate appeared to be associated with higher rates of adverse events than intranasal dexmedetomidine. However, the evidence for the outcomes for oral chloral hydrate versus intravenous pentobarbital, rectal sodium thiopental, intranasal dexmedetomidine, and music therapy was mostly of low certainty, therefore the findings should be interpreted with caution. Further research should determine the effects of oral chloral hydrate on major clinical outcomes such as successful completion of procedures, requirements for an additional sedative agent, and degree of sedation measured using validated scales, which were rarely assessed in the studies included in this review. The safety profile of chloral hydrate should be studied further, especially for major adverse effects such as oxygen desaturation.

Systematic Review: Rectal Administration of Medications for Pediatric Procedural Sedation

BACKGROUND

Per rectum (PR) medication delivery is an alternative to traditional oral (PO), intravenous (IV), or intramuscular (IM) administration of medication for procedural sedation of pediatric emergency department patients. However, many emergency physicians are unfamiliar with its use, and there are no widely adopted guidelines or reviews dedicated to this topic.

OBJECTIVE

Our aim was to provide emergency physicians with an overview of PR procedural sedation medications in pediatric patients.

METHODS

We performed a PubMed literature search of relevant keywords limited to studies of human subjects published in English between January 1, 1990 and December 31, 2017. We excluded case reports, general review articles, editorial/opinion pieces, correspondence, and abstracts. Two of the authors then conducted a structured review of the selected studies.

RESULTS

A total of 315 PubMed citations meeting the search criteria were found. Twenty-eight articles were included for final detailed review. Only 4 of the 28 included studies were conducted in the emergency department setting. A total of 9 different medications have been studied for PR procedural sedation. Sedation effectiveness ranged from 40% to 98%. No life-threatening complications were reported in any of the included clinical trials. Hypoxia was found to occur in up to 10% of those receiving PR sedation.

CONCLUSIONS

Pediatric procedural sedation with PR medications appears to be feasible, moderately effective, and safe based on our review of the current literature. However, further studies on its applicability in the emergency department setting are needed.

Chloral hydrate as a sedating agent for neurodiagnostic procedures in children

BACKGROUND

Paediatric neurodiagnostic investigations, including brain neuroimaging and electroencephalography (EEG), play an important role in the assessment of neurodevelopmental disorders. The use of an appropriate sedative agent is important to ensure the successful completion of the neurodiagnostic procedures, particularly in children, who are usually unable to remain still throughout the procedure.

OBJECTIVES

To assess the effectiveness and adverse effects of chloral hydrate as a sedative agent for non-invasive neurodiagnostic procedures in children.

SEARCH METHODS

We used the standard search strategy of the Cochrane Epilepsy Group. We searched MEDLINE (OVID SP) (1950 to July 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, Issue 7, 2017), Embase (1980 to July 2017), and the Cochrane Epilepsy Group Specialized Register (via CENTRAL) using a combination of keywords and MeSH headings.

SELECTION CRITERIA

We included randomised controlled trials that assessed chloral hydrate agent against other sedative agent(s), non-drug agent(s), or placebo for children undergoing non-invasive neurodiagnostic procedures.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the studies for their eligibility, extracted data, and assessed risk of bias. Results were expressed in terms of risk ratio (RR) for dichotomous data, mean difference (MD) for continuous data, with 95% confidence intervals (CIs).

MAIN RESULTS

We included 13 studies with a total of 2390 children. The studies were all conducted in hospitals that provided neurodiagnostic services. Most studies assessed the proportion of sedation failure during the neurodiagnostic procedure, time for adequate sedation, and potential adverse effects associated with the sedative agent.The methodological quality of the included studies was mixed, as reflected by a wide variation in their 'Risk of bias' profiles. Blinding of the participants and personnel was not achieved in most of the included studies, and three of the 13 studies had high risk of bias for selective reporting. Evaluation of the efficacy of the sedative agents was also underpowered, with all the comparisons performed in single small studies.Children who received oral chloral hydrate had lower sedation failure when compared with oral promethazine (RR 0.11, 95% CI 0.01 to 0.82; 1 study, moderate-quality evidence). Children who received oral chloral hydrate had a higher risk of sedation failure after one dose compared to those who received intravenous pentobarbital (RR 4.33, 95% CI 1.35 to 13.89; 1 study, low-quality evidence), but after two doses there was no evidence of a significant difference between the two groups (RR 3.00, 95% CI 0.33 to 27.46; 1 study, very low-quality evidence). Children who received oral chloral hydrate appeared to have more sedation failure when compared with music therapy, but the quality of evidence was very low for this outcome (RR 17.00, 95% CI 2.37 to 122.14; 1 study). Sedation failure rates were similar between oral chloral hydrate, oral dexmedetomidine, oral hydroxyzine hydrochloride, and oral midazolam.Children who received oral chloral hydrate had a shorter time to achieve adequate sedation when compared with those who received oral dexmedetomidine (MD -3.86, 95% CI -5.12 to -2.6; 1 study, moderate-quality evidence), oral hydroxyzine hydrochloride (MD -7.5, 95% CI -7.85 to -7.15; 1 study, moderate-quality evidence), oral promethazine (MD -12.11, 95% CI -18.48 to -5.74; 1 study, moderate-quality evidence), and rectal midazolam (MD -95.70, 95% CI -114.51 to -76.89; 1 study). However, children with oral chloral hydrate took longer to achieve adequate sedation when compared with intravenous pentobarbital (MD 19, 95% CI 16.61 to 21.39; 1 study, low-quality evidence) and intranasal midazolam (MD 12.83, 95% CI 7.22 to 18.44; 1 study, moderate-quality evidence).No data were available to assess the proportion of children with successful completion of neurodiagnostic procedure without interruption by the child awakening. Most trials did not assess adequate sedation as measured by specific validated scales, except in the comparison of chloral hydrate versus intranasal midazolam and oral promethazine.Compared to dexmedetomidine, chloral hydrate was associated with a higher risk of nausea and vomiting (RR 12.04 95% CI 1.58 to 91.96). No other adverse events were significantly associated with chloral hydrate (including behavioural change, oxygen desaturation) although there was an increased risk of adverse events overall (RR 7.66, 95% CI 1.78 to 32.91; 1 study, low-quality evidence).

AUTHORS' CONCLUSIONS

The quality of evidence for the comparisons of oral chloral hydrate against several other methods of sedation was very variable. Oral chloral hydrate appears to have a lower sedation failure rate when compared with oral promethazine for children undergoing paediatric neurodiagnostic procedures. The sedation failure was similar for other comparisons such as oral dexmedetomidine, oral hydroxyzine hydrochloride, and oral midazolam. When compared with intravenous pentobarbital and music therapy, oral chloral hydrate had a higher sedation failure rate. However, it must be noted that the evidence for the outcomes for the comparisons of oral chloral hydrate against intravenous pentobarbital and music therapy was of very low to low quality, therefore the corresponding findings should be interpreted with caution.Further research should determine the effects of oral chloral hydrate on major clinical outcomes such as successful completion of procedures, requirements for additional sedative agent, and degree of sedation measured using validated scales, which were rarely assessed in the studies included in this review. The safety profile of chloral hydrate should be studied further, especially the risk of major adverse effects such as bradycardia, hypotension, and oxygen desaturation.

Options and Considerations for Procedural Sedation in Pediatric Imaging

As pediatric imaging capabilities have increased in scope, so have the complexities of providing procedural sedation in this environment. While efforts by many organizations have dramatically increased the safety of pediatric procedural sedation in general, radiology sedation creates several special challenges for the sedation provider. These challenges require implementation of additional safeguards to promote safety during sedation while maintaining effective and efficient care. Multiple agent options are available, and decisions regarding which agent(s) to use should be determined by both patient needs (i.e., developmental capacities, underlying health status, and previous experiences) and procedural needs (i.e., duration, need for immobility, and invasiveness). Increasingly, combinations of agents to either achieve the conditions required or mitigate/counterbalance adverse effects of single agents are being utilized with success. To continue to provide effective imaging sedation, it is incumbent on sedation providers to maintain familiarity with continuing evolutions within radiology environments, as well as comfort and competence with multiple sedation agents/regimens. This review discusses the challenges associated with radiology sedation and outlines various available agent options and combinations, with the intent of facilitating appropriate matching of agent(s) with patient and procedural needs.

Pharmacological sedation for cranial computed tomography in children after minor blunt head trauma

OBJECTIVE

Children evaluated in emergency departments for blunt head trauma (BHT) frequently undergo computed tomography (CT), with some requiring pharmacological sedation. Cranial CT sedation complications are understudied. The objective of this study was to document the frequency, type, and complications of pharmacological sedation for cranial CT in children.

METHODS

We prospectively enrolled children (younger than 18 years) with minor BHT presenting to 25 emergency departments from 2004 to 2006. Data collected included sedation agent and complications. We excluded patients with Glasgow Coma Scale scores of less than 14.

RESULTS

Of 57,030 eligible patients, 43,904 (77%) were enrolled in the parent study; 15,176 (35%) had CT scans performed or planned, and 527 (3%) received pharmacological sedation for CT. Sedated patients' characteristics were as follows: median age, 1.7 years (interquartile range, 1.1-2.5 years); male 61%; Glasgow Coma Scale score of 15, 86%; traumatic brain injury on CT, 8%. There were 488 patients (93%) who received 1 sedative. Sedation use (0%-21%) and regimen varied by site. Pentobarbital (n = 164) and chloral hydrate (n = 149) were the most frequently used agents. Sedation complications occurred in 49 patients (9%; 95% confidence interval [CI], 7%-12%): laryngospasm 1 (0.2%; 95% CI, 0%-1.1%), failed sedation 31 (6%; 95% CI, 4%-8%), vomiting 6 (1%; 95% CI, 0.4%-2%), hypotension 13 (4%; 95% CI, 2%-7%), and hypoxia 1 (0.2%; 95% CI, 0%-2%). No cases of apnea, aspiration, or reversal agent use occurred. One patient required intubation. Vomiting and failed sedation were most common with chloral hydrate.

CONCLUSIONS

Pharmacological sedation is infrequently used for children with minor BHT undergoing CT, and complications are uncommon. The variability in sedation medications and frequency suggests a need for evidence-based guidelines.

Evidence of safety of chloral hydrate for prolonged sedation in PICU in a tertiary teaching hospital in southern Brazil

OBJECTIVE

To evaluate the utilization of chloral hydrate (CH) for sedation in pediatric intensive care and the incidence of adverse drug reactions.

METHODS

This was a cohort study including patients with prescription of chloral hydrate hospitalized in the pediatric intensive care unit (PICU) of a university-affiliated, general, tertiary teaching hospital. Data were collected from a spreadsheet for daily monitoring, and clinical events registered in the patient records were analyzed to evaluate the causality of suspected adverse drug reactions (ADR), applying the Naranjo algorithm.

RESULTS

Three hundred forty-three patients who had been prescribed CH were studied. Ages ranged from 0 to 18 years, and 63% were male. The most frequent cause for PICU admission was bronchiolitis (77.6%), and 58.6% required mechanical ventilation. In 92.7% of cases, CH was indicated to control agitation and in 7.3% for procedural sedation. The median time of CH use was 6 days. The incidence of suspected ADR was 22.7% ± 2.3. Oxygen desaturation was the most frequent adverse event (64.6%), followed by hypotension. Specific treatment was required in 60.9% of the events. Chloral hydrate as cause for suspected ADR was classified as probable in 39 events (35.5%) and as possible in 70 (63.6%), and no event was classified as definite. In the multivariate analysis, only mechanical ventilation was predictive of ADR to CH.

CONCLUSIONS

The study described the clinical practice of sedation with CH in the PICU setting of a tertiary teaching hospital in southern Brazil. Data suggest that CH is an alternative for prolonged sedation in PICU

Cardiac arrhythmias induced by chloral hydrate in rhesus monkeys

Chloral hydrate has been long used as a safe sedative and hypnotic drug in humans. However, reports on its cardiovascular adverse effects have been published from time to time. The present study was undertaken to use Rhesus monkeys as a model to define the dose regiment of chloral hydrate at which cardiac arrhythmias can be induced and the consequences of the cardiac events. Male Rhesus monkeys of 2-3 years old were intravenously infused with chloral hydrate starting at 50 mg/kg with an increasing increment of 25 mg/kg until the occurrence of cardiac arrhythmias. In addition, a traditional up-and-down dosing procedure was applied to define a single dose level at which cardiac arrhythmias can be induced. The data obtained showed that when the sequentially escaladed dose reached 125 mg/kg, cardiac arrhythmias occurred in all monkeys tested. The single effective dose to cause cardiac arrhythmias calculated from the crossover analysis was 143 ± 4 mg/kg. This value would be equivalent to 68.6 ± 1.9 mg/kg for children and 46.4 ± 1.3 mg/kg for adults in humans. Under either multiple or single dose condition, cardiac arrhythmias did not occur before 40 min after the onset of anesthesia induced by chloral hydrate. Cardiac arrhythmias were recovered without help at the end of the anesthesia in most cases, but also continued after the regain of consciousness in some cases. The cardiac arrhythmias were accompanied with compromised cardiac function including suppressed fractional shortening and ejection fraction. This study thus suggests that cautions need to be taken when chloral hydrate is used above certain levels and beyond a certain period of anesthesia, and cardiac arrhythmias induced by chloral hydrate need to be closely monitored because compromised cardiac function may occur simultaneously. In addition, patients with cardiac arrhythmias induced by chloral hydrate should be monitored even after they are recovered from the anesthesia.

Comprehensive integrated spirometry using raised volume passive and forced expirations and multiple-breath nitrogen washout in infants

With the rapid somatic growth and development in infants, simultaneous accurate measurements of lung volume and airway function are essential. Raised volume rapid thoracoabdominal compression (RTC) is widely used to generate forced expiration from an airway opening pressure of 30 cmH(2)O (V(30)). The (dynamic) functional residual capacity (FRC(dyn)) remains the lung volume most routinely measured. The aim of this study was to develop comprehensive integrated spirometry that included all subdivisions of lung volume at V(30) or total lung capacity (TLC(30)). Measurements were performed on 17 healthy infants aged 8.6-119.7 weeks. A commercial system for multiple-breath nitrogen washout (MBNW) to measure lung volumes and a custom made system to perform RTC were used in unison. A refined automated raised volume RTC and the following two novel single maneuvers with dual volume measurements were performed from V(30) during a brief post-hyperventilation apneic pause: (1) the passive expiratory flow was integrated to produce the inspiratory capacity (IC) and the static (passive) FRC (FRC(st)) was estimated by initiating MBNW after end-passive expiration; (2) RTC was initiated late during passive expiration, flow was integrated to produce the slow vital capacity ((j)SVC) and the residual volume (RV) was measured by initiating MBNW after end-expiration while the jacket (j) was inflated. Intrasubject FRC(dyn) and FRC(st) measurements overlapped (p=0.6420) but neither did with the RV (p<0.0001). Means (95% confidence interval) of FRC(dyn), IC, FRC(st), (j)SVC, RV, forced vital capacity and tidal volume were 21.2 (19.7-22.7), 36.7 (33.0-40.4), 21.2 (19.6-22.8), 40.7 (37.2-44.2), 18.1 (16.6-19.7), 40.7 (37.1-44.2) and 10.2 (9.6-10.7)ml/kg, respectively. Static lung volumes and capacities at V(30) and variables from the best forced expiratory flow-volume curve were dependent on age, body length and weight. In conclusion, we developed a comprehensive physiologically integrated approach for in-depth investigation of lung function at V(30) in infants.

A novel physiological investigation of the functional residual capacity by the bias flow nitrogen washout technique in infants

The dynamic functional residual capacity (FRC(dyn)), the lung volume most routinely measured in infants, is an unreliable volume landmark. In addition to the FRC(dyn), we measured the (passive) static FRC (FRC(st)) by inducing a brief post-hyperventilation apnea (PHA) in 33 healthy infants aged 7.4-127.2 weeks. A commercial system for nitrogen (N2) washout to measure FRC, and a custom made system to monitor and record flow and airway opening pressure signals in real-time were used in unison. Infants were manually hyperventilated to induce a PHA. After the last passive expiration, FRC(st) was estimated by measuring the volume of N2 expired after end-passive expiratory switching of the inspired gas from room air to 100% oxygen during the post-expiratory apneic pause. Repeatable intrasubject FRC(st) and FRC(dyn) measurements overlapped in most infants including the younger ones (P = 0.2839). Mean (95% confidence interval [CI]) FRC(st) was 21.1 (20.0-22.3), and error-corrected FRC(dyn) was 21.4 (20.4-22.4) ml/kg. Mean (washout time [t]) tFRC(st) was longer than tFRC(dyn) 60 sec (95% CI 55-65) versus 47 sec (95% CI 43-51) (P < 0.0001). The FRC and washout time were dependent on body length, weight and age. We conclude that the FRC(st) is not different from the FRC(dyn) in infants. The FRC(st) is a reliable volume landmark because the PHA stabilizes the end-expiratory level by potentially abolishing the sedated infant's breathing strategies. The FRC(st) lacks potential sources of errors and disadvantages associated with measuring the FRC(dyn). The findings cast significant doubt on the traditional physiology of air trapping in healthy infants' lungs.

Oral sedation with midazolam and diphenhydramine compared with midazolam alone in children undergoing magnetic resonance imaging

BACKGROUND

The purpose of this study was to compare the safety and efficacy of oral midazolam and midazolam-diphenhydramine combination to sedate children undergoing magnetic resonance imaging (MRI).

METHODS

We performed a prospective randomized double-blind study in 96 children who were randomly allocated into two groups. Group D received oral diphenhydramine (1.25 mg x kg(-1)) with midazolam (0.5 mg x kg(-1)), and Group P received oral placebo with midazolam (0.5 mg x kg(-1)) alone. Sedation scores, onset and duration of sleep were evaluated. Adverse effects, including hypoxemia, failed sedation, and the return of baseline activity, were documented.

RESULTS

Diphenhydramine facilitated an earlier onset of midazolam sedation (P < 0.01), and higher sedation scores (P < 0.01). In children who received midazolam alone, 20 (41%) were inadequately sedated, compared with 9 (18%) children who received midazolam and diphenhydramine combination (P < 0.01). Time to complete recovery was not significantly different between the two groups.

CONCLUSIONS

Our study indicates that the combination of oral diphenhydramine with oral midazolam resulted in safe and effective sedation for children undergoing MRI. The use of this combination might be more advantageous compared with midazolam alone, resulting in less sedation failure during MRI.

Efficacy and adverse effects of rectal thiamylal with oral triclofos for children undergoing magnetic resonance imaging

We studied the efficacy and adverse effects of rectal thiamylal in combination with oral triclofos in sedation for pediatric magnetic resonance imaging. Five hundred forty-six children underwent MRI examination from January of 1997 to December of 2001. Among them, 10mg/kg of rectal thiamylal was administrated after oral triclofos in 378 children. Successful sedation was obtained in 321 of 378 patients (85%) after a single rectal administration of thiamylal. Totally, 369 children (98%) could undergo MRI examination completely under successful sedation. Adverse effect was observed only in one patient showing respiratory depression. Rectal thiamylal is effective for sedation for MRI in children. Adverse effect was rare in our patients. Although the risk of side effect was considered to be rare, we should follow principles for the sedation of children.