A pharmacokinetically based propofol dosing strategy for sedation of the critically ill, mechanically ventilated pediatric patient

Neonatal Anesthesia and Oxidative Stress

Neonatal anesthesia, while often essential for surgeries or imaging procedures, is accompanied by significant risks to redox balance in the brain due to the relatively weak antioxidant system in children. Oxidative stress is characterized by concentrations of reactive oxygen species (ROS) that are elevated beyond what can be accommodated by the antioxidant defense system. In neonatal anesthesia, this has been proposed to be a contributing factor to some of the negative consequences (e.g., learning deficits and behavioral abnormalities) that are associated with early anesthetic exposure. In order to assess the relationship between neonatal anesthesia and oxidative stress, we first review the mechanisms of action of common anesthetic agents, the key pathways that produce the majority of ROS, and the main antioxidants. We then explore the possible immediate, short-term, and long-term pathways of neonatal-anesthesia-induced oxidative stress. We review a large body of literature describing oxidative stress to be evident during and immediately following neonatal anesthesia. Moreover, our review suggests that the short-term pathway has a temporally limited effect on oxidative stress, while the long-term pathway can manifest years later due to the altered development of neurons and neurovascular interactions.

Safety of Propofol versus Nonpropofol-Based Sedation in Children Undergoing Gastrointestinal Endoscopy: A Systematic Review and Meta-Analysis

BACKGROUND

The majority of children who undergo gastrointestinal (GI) endoscopy require anesthesia or procedural sedation for comfort, cooperation, and procedure efficiency. The safety profile of propofol is not well established in children but has been studied in the literature.

OBJECTIVE

The aim of this study is to evaluate and compare the safety of propofol-only sedation for GI endoscopy procedures to other anesthetic regimes in the pediatric population.

METHODS

A search was conducted in the MEDLINE, Embase, and Cochrane Library databases. Randomized clinical trials and prospective cohorts were included in the study.

RESULTS

No significant difference was noted in total complications between the two cohorts with a pooled OR of 1.31 (95% CI: 0.57-3.04, chi2 = 0.053, I2 = 54.31%). The pooled rate of complications in the studies was 23.4% for those receiving propofol only and 18.2% for those receiving other anesthetic regimens. Sensitivity analysis was performed removing a study with a very different control comparison compared to the rest of the studies included. Once excluded, there was minimal heterogeneity in the remaining studies and a significant difference in overall complications was detected, with more complications seen in the propofol-only group compared to the other anesthetic groups (OR 1.87, 95% CI 1.09-3.20).

CONCLUSION

Significantly higher incidence of cardiorespiratory complications was noted in the propofol-only versus other anesthetic regimens in pediatric patients undergoing GI endoscopy in this meta-analysis. However, the overall quality of the evidence is very low.

HOW TO APPLY THIS KNOWLEDGE FOR ROUTINE CLINICAL PRACTICE

Clinicians providing sedation to a pediatric population for GI endoscopy should consider there may be increased risks when using a propofol-only regimen, but further study is needed.

Factors affecting propofol dosage for sedation in pediatric oncology

BACKGROUND

There is limited reference data for determining the appropriate dose of propofol for individual patients. Therefore, we investigated the factors affecting propofol dosage for pediatric patients undergoing sedation for computed tomography (CT) simulation.

METHODS

We retrospectively analyzed the electronic medical records of pediatric patients who underwent CT simulation for proton therapy following a cancer diagnosis at the National Cancer Center (Korea) between 1 May 2012 and 30 April 2016. We evaluated the following factors, which reflect comorbidities or chronic illness in pediatric oncology patients: age, tumor lesion, preterm birth, American Society of Anesthesiologists (ASA) classification, pre-sedation temperature, history of propofol use, nothing by mouth time, chemotherapy history, pre-sedation laboratory findings, regular medication (opioids, anticonvulsants), and use of diuretics. A regression analysis was performed and P < 0.05 was considered statistically significant.

RESULTS

Electronic medical records of 84 pediatric cancer patients were used in the analysis. Patients in ASA classes 1-2 required approximately 43% more propofol than patients in classes 3-4 (exp(β), 1.43; 95%CI: 1.21-1.69, P < 0.001).

CONCLUSION

American Society of Anesthesiologists class 3 or 4 is an independent indicator of decreased propofol dosage for pediatric oncology patients during sedation.

Comparison in anesthetic effects of propofol among patients with different ABO blood groups

Our study was aimed to investigate anesthetic effects of propofol in patients with different blood groups.A total of 72 participants were enrolled from patients arranged for surgeries of cholecystectomy, tonsillectomy, and spinal operation. Each blood group (A, B, AB, and O) contained 18 participants. Mean arterial pressure (MAP), heart rate (HR), and bispectral index (BIS) were assayed with Philips monitor. These indexes were observed before propofol anesthesia (T0), and then were recorded when concentration of propofol was 1 μg/mL (T1), 2 μg/mL (T2), 3 μg/mL (T3), and 4 μg/mL (T4). The differences in MAP, HR, and BIS at T0 among groups were compared with the χ test. Multiple comparisons were adopted to calculate the differences in MAP, HR, and BIS between groups at T1, T2, T3, and T4.No significant differences in age, sex, and weight of all groups were found (P > .05). Before propofol anesthesia (T0), all the participants exhibited no differences in MAP, HR, and BIS (P > .05). Subsequently, we found obvious differences in ΔMAP, ΔHR, and ΔBIS between groups. The patients in the B blood group showed highest ΔMAP and ΔHR at each time point (P < .05 for both). As for ΔBIS, patients in A blood group exhibited highest value at T3 and T4 (P < .05).The blood group remarkably affects the anesthetic effects of propofol.

Pediatric Anti-N-Methyl-d-Aspartate Receptor Encephalitis: A Review with Pooled Analysis and Critical Care Emphasis

PURPOSE

Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is being recognized with increasing frequency among children. Given the paucity of evidence to guide the critical care management of these complex patients, we provide a comprehensive review of the literature with pooled analysis of published case reports and case series.

METHODS

We performed a comprehensive literature search using PubMed, Scopus, EMBASE, and Web of Science for relevant published studies. The literature search was conducted using the terms NMDA, anti-NMDA, Anti-N-methyl-d-aspartate, pediatric encephalitis, and anti-NMDAR and included articles published between 2005 and May 1, 2016.

RESULTS

Forty-eight references met inclusion criteria accounting for 373 cases. For first-line treatments, 335 (89.8%) received high-dose corticosteroids, 296 received intravenous immunoglobulin (79.3%), and 116 (31%) received therapeutic plasma exchange. In these, 187 children (50.1%) had a full recovery with only minor deficits, 174 patients (46.7%) had partial recovery with major deficits, and 12 children died. In addition, 14 patients were reported to require mechanical ventilation.

CONCLUSION

Anti-NMDA encephalitis is a formidable disease with great variation in clinical presentation and response to treatment. With early recognition of this second most common cause of pediatric encephalitis, a multidisciplinary approach by physicians may provide earlier access to first- and second-line therapies. Future studies are needed to examine the efficacy of these current therapeutic strategies on long-term morbidity.

Clinical Pharmacology Studies in Critically Ill Children

Developmental and physiological changes in children contribute to variation in drug disposition with age. Additionally, critically ill children suffer from various life-threatening conditions that can lead to pathophysiological alterations that further affect pharmacokinetics (PK). Some factors that can alter PK in this patient population include variability in tissue distribution caused by protein binding changes and fluid shifts, altered drug elimination due to organ dysfunction, and use of medical interventions that can affect drug disposition (e.g., extracorporeal membrane oxygenation and continuous renal replacement therapy). Performing clinical studies in critically ill children is challenging because there is large inter-subject variability in the severity and time course of organ dysfunction; some critical illnesses are rare, which can affect subject enrollment; and critically ill children usually have multiple organ failure, necessitating careful selection of a study design. As a result, drug dosing in critically ill children is often based on extrapolations from adults or non-critically ill children. Dedicated clinical studies in critically ill children are urgently needed to identify optimal dosing of drugs in this vulnerable population. This review will summarize the effect of critical illness on pediatric PK, the challenges associated with performing studies in this vulnerable subpopulation, and the clinical PK studies performed to date for commonly used drugs.

How the cortico-thalamic feedback affects the EEG power spectrum over frontal and occipital regions during propofol-induced sedation

Increasing concentrations of the anaesthetic agent propofol initially induces sedation before achieving full general anaesthesia. During this state of anaesthesia, the observed specific changes in electroencephalographic (EEG) rhythms comprise increased activity in the δ- (0.5-4 Hz) and α- (8-13 Hz) frequency bands over the frontal region, but increased δ- and decreased α-activity over the occipital region. It is known that the cortex, the thalamus, and the thalamo-cortical feedback loop contribute to some degree to the propofol-induced changes in the EEG power spectrum. However the precise role of each structure to the dynamics of the EEG is unknown. In this paper we apply a thalamo-cortical neuronal population model to reproduce the power spectrum changes in EEG during propofol-induced anaesthesia sedation. The model reproduces the power spectrum features observed experimentally both in frontal and occipital electrodes. Moreover, a detailed analysis of the model indicates the importance of multiple resting states in brain activity. The work suggests that the α-activity originates from the cortico-thalamic relay interaction, whereas the emergence of δ-activity results from the full cortico-reticular-relay-cortical feedback loop with a prominent enforced thalamic reticular-relay interaction. This model suggests an important role for synaptic GABAergic receptors at relay neurons and, more generally, for the thalamus in the generation of both the δ- and the α- EEG patterns that are seen during propofol anaesthesia sedation.

Propofol: a review of its role in pediatric anesthesia and sedation

Propofol is an intravenous agent used commonly for the induction and maintenance of anesthesia, procedural, and critical care sedation in children. The mechanisms of action on the central nervous system involve interactions at various neurotransmitter receptors, especially the gamma-aminobutyric acid A receptor. Approved for use in the USA by the Food and Drug Administration in 1989, its use for induction of anesthesia in children less than 3 years of age still remains off-label. Despite its wide use in pediatric anesthesia, there is conflicting literature about its safety and serious adverse effects in particular subsets of children. Particularly as children are not "little adults", in this review, we emphasize the maturational aspects of propofol pharmacokinetics. Despite the myriad of propofol pharmacokinetic-pharmacodynamic studies and the ability to use allometrical scaling to smooth out differences due to size and age, there is no optimal model that can be used in target controlled infusion pumps for providing closed loop total intravenous anesthesia in children. As the commercial formulation of propofol is a nutrient-rich emulsion, the risk for bacterial contamination exists despite the Food and Drug Administration mandating addition of antimicrobial preservative, calling for manufacturers' directions to discard open vials after 6 h. While propofol has advantages over inhalation anesthesia such as less postoperative nausea and emergence delirium in children, pain on injection remains a problem even with newer formulations. Propofol is known to depress mitochondrial function by its action as an uncoupling agent in oxidative phosphorylation. This has implications for children with mitochondrial diseases and the occurrence of propofol-related infusion syndrome, a rare but seriously life-threatening complication of propofol. At the time of this review, there is no direct evidence in humans for propofol-induced neurotoxicity to the infant brain; however, current concerns of neuroapoptosis in developing brains induced by propofol persist and continue to be a focus of research.

Total intravenous anesthesia will supercede inhalational anesthesia in pediatric anesthetic practice

Inhalational anesthesia has dominated the practice of pediatric anesthesia. However, as the introduction of agents such as propofol, short-acting opioids, midazolam, and dexmedetomidine a monumental change has occurred. With increasing use, the overwhelming advantages of total intravenous anesthesia (TIVA) have emerged and driven change in practice. These advantages, outlined in this review, will justify why TIVA will supercede inhalational anesthesia in future pediatric anesthetic practice.

A predictive pharmacokinetic/pharmacodynamic model of fentanyl for analgesia/sedation in neonates based on a semi-physiologic approach

BACKGROUND AND OBJECTIVES

Fentanyl is a synthetic opioid commonly used as an anesthetic and also increasingly popular as a sedative agent in neonates. Initial dosage regimens in this population are often empirically derived from adults on a body weight basis. However, ontogenic maturation processes related to drug disposition are not necessarily always body weight correlates. We developed a predictive pharmacokinetic/pharmacodynamic model that includes growth and maturation physiologic changes for fentanyl in neonatal care.

METHODS

Key pharmacokinetic variables and principles (protein binding, clearance, distribution) as related to fentanyl pharmacokinetic/pharmacodynamic behavior in adults (tricompartmental model) and to neonatal physiologic data (organ weights and blood flows, body composition, renal and hepatic function, etc.) were used to guide the building of a semi-physiologic ontogenic model. The model applies to a normal-term neonate without any other intervention. Then, extension to a pharmacokinetic/pharmacodynamic link model for fentanyl was made. The final model was evaluated by predicting the time course of plasma concentrations and the effect of a standard regimen of 10.5 μg/kg over a 1-h period followed by 1.5 μg/kg/h for 48 h.

RESULTS

Hepatic clearance was linked to ontogeny of unbound fraction and of α1-acid glycoprotein. All parameters were reduced in the neonate compared to adults but in a differing proportion due to qualitative changes in physiology that are analyzed and accounted for. Systemic clearance (CLS), volume of the central compartment (V1) and steady-state volume of distribution predicted by the model were 0.028 L/min, 1.26 L, and 22.04 L, respectively. Weight-corrected parameters generally decreased in adults compared with neonates, but differentially, e.g., CLS = 0.0093 versus 0.0088 L/min/kg, while V1 = 0.42 versus 0.18 L/kg (neonates vs. adults). Under such complexity a pharmacokinetic/pharmacodynamic model is the appropriate method for rational efficacy targeting. Fentanyl pharmacodynamics in neonates were considered to be similar to those in adults except for the equilibrium rate constant, which was also scaled on an ontogenic basis. The model adequately predicted the reported mean expected concentration-time profiles for the standard regimen.

CONCLUSIONS

Integrated pharmacokinetic/pharmacodynamic modeling showed that the usually prescribed dosage regimens of fentanyl in neonates may not always provide the optimum degree of sedation. The model could be used in optimal design of clinical trials for this vulnerable population. Prospective clinical testing is the reasonable next step.

How to control propofol infusion in pediatric patients undergoing gamma knife radiosurgery

INTRODUCTION

Although Gamma Knife radiosurgery (GKS) is commonly performed under local anesthesia, general anesthesia is sometimes required. The authors previously reported a remote-controlled patient management system consisting of propofol-based general anesthesia with a target-controlled infusion (TCI) that we designed for pediatric GKS. However, a commercially available propofol TCI system has age and weight limitations (<16 years and <30 kg). We examined a manually controlled regimen of propofol appropriate for pediatric GKS.

METHODS

A pharmacokinetic model of the TIVA Trainer© with Paedfusor's parameter was used. A manually controlled infusion scheme to achieve a sufficient level of propofol for pediatric GKS was examined in five models ranging from 10 to 30 kg.

RESULTS

Following a loading dose of 3.0 mg/kg, the combination of continuous infusion of 14, 12, 10, and 8 mg/kg/h resulted in a target concentration of 3.0-4.0 μg/ml, the required level for pediatric GKS.

CONCLUSION

Propofol titration is a key issue in GKS. Manual infusion is less accurate than TCI, but the combination of a small bolus and continuous infusion might be a substitute. Considering the characteristics of propofol pharmacokinetics in children, co-administration of opioids is recommended.

Remifentanil and propofol for weaning of mechanically ventilated pediatric intensive care patients

Mechanically ventilated pediatric intensive care patients usually receive an analgesic and sedative to keep them comfortable and safe. However, common drugs like fentanyl and midazolam have a long context sensitive half time, resulting in prolonged sedation and an unpredictable extubation time. Children often awake slowly and struggle against the respirator, although their respiratory drive and their airway reflexes are not yet sufficient for extubation. In this pilot study, we replaced fentanyl and midazolam at the final phase of the weaning process with remifentanil and propofol. Twenty-three children aged 3 months-10 years were enrolled. Remifentanil and propofol revealed throughout excellent or good weaning conditions with rapid transition from hypnosis to the development of regular spontaneous breathing, airway protective reflexes, and an appropriate level of alertness. Extubation time following discontinuation of the remifentanil and propofol infusion was only 24 ± 20 min (5-80 min). We conclude that the combination of remifentanil and propofol is a promising option to improve the weaning conditions of pediatric intensive care patients. Randomized controlled trials are needed to compare remifentanil and propofol with conventional weaning protocols.

Propofol and children--what we know and what we do not know

The pharmacokinetics of propofol are relatively well described in the pediatric population. Recent work has confirmed the validity of allometric scaling for predicting propofol disposition across different species and for describing pediatric ontogenesis. In the first year of life, allometric models require adjustment to reflect ontogeny of maturation. Pharmacodynamic data for propofol in children are scarcer, because of practical difficulties in data collection and the limitations of currently available depth of anesthesia monitors for pediatric use. Hence, questions relating to the comparative sensitivity of children to propofol, and differences in time to peak effect relative to adults, remain unanswered. K(eo) half-lives have been determined for pediatric kinetic models using time to peak effect techniques but are not currently incorporated into commercially available target-controlled infusion pumps.

Efficacy of sedation regimens to facilitate mechanical ventilation in the pediatric intensive care unit: a systematic review

OBJECTIVE

Children admitted to pediatric intensive care units (PICUs) often receive sedatives to facilitate mechanical ventilation. However, despite their widespread use, data supporting appropriate dosing, safety, and optimal regimens for sedation during mechanical ventilation are lacking. Therefore, we conducted a systematic review of published data regarding efficacy of sedation to facilitate mechanical ventilation in PICU patients. Our primary objective was to identify and evaluate the quality of evidence supporting sedatives used in PICUs for this purpose.

DATA SOURCES

We searched MEDLINE, EMBASE, and The Cochrane Registry of Clinical Trials from 1966 to June 2008 to identify published articles evaluating sedation regimens to facilitate mechanical ventilation in PICU patients.

STUDY SELECTION

We included only those studies of intubated PICU or pediatric cardiac intensive care unit patients receiving pharmacologic agents to facilitate mechanical ventilation that reported quality of sedation as an outcome.

DATA EXTRACTION

We analyzed studies separately for study type and by agents being studied. Studies were appraised using criteria of particular importance for reviews evaluating sedatives.

DATA SYNTHESIS

Our search strategy yielded 39 studies, including 3 randomized trials, 15 cohort studies, and 21 cases series or reports. The 39 studies evaluated a total of 39 different sedation regimens, with 21 different scoring systems, in a total of 901 PICU/cardiac intensive care unit patients ranging in age from 3 days to 19 years old. Most of the studies were small (<30 patients), and only four studies compared one or more agents to another. Few studies thoroughly evaluated drug safety, and only one study met all quality criteria.

CONCLUSIONS

Despite the widespread use of sedatives to facilitate mechanical ventilation in the PICU, we found that high-quality evidence to guide clinical practice is still limited. Pediatric randomized, controlled trials with reproducible methods and assessment of drug safety are needed.

Propofol sedation: intensivists' experience with 7304 cases in a children's hospital

OBJECTIVE

The objective of this study was to determine the safety profile of propofol as a deep-sedation agent in a primarily outpatient program consisting of pediatric critical care physicians and specifically trained nurses with oversight provided by anesthesiology. One hypothesis was investigated: adverse events and/or airway interventions are more likely to occur in children with an abnormal airway score.

METHODS

A 36-month dual-site prospective, observational, clinical study was conducted in a single center with interchangeable providers operating within the guidelines of a single sedation program. A total of 7304 propofol sedations for 4464 unique patients who ranged in age from 1 month to 21 years were studied; >97% of the children were >1 year of age.

RESULTS

The following adverse reactions were identified, and a descriptive statistical analysis of the data were performed: mild oxygen desaturation (85%-90%), 1.73%; serious oxygen desaturation (<85%), 2.9%; laryngospasm, 0.27%; regurgitation without aspiration, 0.05%; regurgitation with aspiration, 0.01%; bronchospasm, 0.15%; and hypotension, 31.4%. Interventions required included oral airway, 0.96%; nasal trumpet, 1.57%; rescue breaths for >1 minute, 0.37%; intubation, 0.03%; volume requirement of >40 mL/kg per hour, 0.11%; sedation-induced ward or PICU admission, 0.04%; cardiac arrest medications, 0%; and aborted sedation or procedure, 0%. We devised an airway score to identify at-risk patients. Patients with an abnormal airway score were significantly more likely to: have oxygen desaturation (13.1% vs 4.3%); require an oral airway (5.9% vs 0.8%); and require a nasal trumpet (13.9% vs 1.2%).

CONCLUSIONS

Propofol has an acceptable safety profile for deep sedation when used in the context of a program with critical care physicians, specifically trained nurses, and anesthesiology oversight. A preprocedure airway score can assist in identifying patients who may require airway interventions.

Development and preliminary psychometric testing of the Multidimensional Assessment of Pain Scale: MAPS

BACKGROUND

This study aimed to test the preliminary psychometric properties of the Multidimensional Assessment Pain Scale (MAPS), a clinical instrument developed for assessing postoperative pain in critically ill preverbal children.

METHODS

The MAPS was developed using pain indicators observed in postoperative critically ill infants. Content validity was established by a panel of experts. The scale was tested for validity and reliability in 43 postoperative children aged 0-31 months admitted to the pediatric intensive care units of two tertiary referral hospitals. Pain was measured concurrently by three independent assessors using the MAPS, the Face, Leg, Activity, Cry, and Consolability scale (FLACC) and the Visual Analog Scale (VAS) to assess concurrent and convergent validity.

RESULTS

Internal consistency was moderate (r = 0.68). Interrater reliability of the MAPS was good (kappa: 0.68-0.84) for all categories and moderate for breathing pattern (kappa = 0.54). Excellent interrater reliability was shown for total MAPS (intraclass correlation 0.91). Agreement measurements between MAPS and FLACC, and MAPS and VAS showed that the risk of measurement error was small.

CONCLUSION

Although initial psychometric testing of the MAPS shows promising results, the tool requires further psychometric testing, including responsiveness to analgesic effect (currently in progress).

The Cerebrovascular Response to Hypocapnia in Children Receiving Propofol

Hypocapnia is used to treat acute increases in intracranial pressure during neurosurgery. Cerebrovascular reactivity to carbon dioxide (CCO(2)R) is preserved above 35 mm Hg ETco(2) in children during propofol anesthesia; however, a plateau effect has been suggested below 35 mm Hg. To further delineate this phenomenon, we measured CCO(2)R by transcranial Doppler (TCD) sonography over small increments in ETco(2) in 27 healthy children. Anesthesia comprised a standardized propofol infusion and a caudal epidural block. A TCD probe was placed to measure middle cerebral artery blood flow velocity (V(mca)). ETco(2) was adjusted between 24 and 40 mm Hg at 1-2 mm Hg increments using an exogenous source of CO(2). There was an exponential relationship between ETco(2) and V(mca) above an ETco(2) value of 30 mm Hg (r = 0.82). However, V(mca) did not change with ETco(2) less than 30 mm Hg (r = 0.06). There were no significant changes in heart rate or arterial blood pressure. We conclude that when contemplating methods to decrease brain volume and intracranial pressure, hyperventilation to ETco(2) values less than 30 mm Hg may not be necessary in children receiving propofol, as no further reduction in cerebral blood flow velocity will be achieved.

Short-term propofol infusion as an adjunct to extubation in burned children

Children who require intubation as a component of their burn management generally need heavy sedation, usually with a combination of opiate and benzodiazepine infusions with a target sensorium of light sleep. When extubation approaches, the need for sedation to prevent uncontrolled extubation can conflict with the desire to lighten sedation enough to ensure that airway protective reflexes are strong. The several hours' half-life of these medications can make this period of weaning challenging. Therefore, the hours preceding extubation are among the most difficult in which to ensure safe adequate sedation. The pharmacokinetics of propofol allow for the rapid emergence of a patient from deep sedation. We have had success with an extubation strategy using short-term propofol infusions in critically ill children. In this work, children were maintained on morphine and midazolam infusions per our unit protocol, escalating doses as required to maintain comfort. Approximately 8 hours before planned extubation, these infusions were decreased by approximately half and propofol infusion added to maintain a state of light sleep. Extubation was planned approximately 8 hours later to allow ample time for the chronically infused opiates and benzodiazepines to be metabolized down to the new steady-state level. Thirty minutes before planned extubation, propofol was stopped while morphine and midazolam infusions were maintained at the reduced level. When the children awakened from the propofol-induced state of light sleep, they were extubated while the reduced infusions of morphine and midazolam were maintained. These were subsequently weaned slowly, depending on the child's need for ongoing pain and anxiety medication, per our unit protocol to minimize the incidence of withdrawal symptoms. Data are shown in the text as mean +/- standard deviation. These 11 children (eight boys and three girls) had an average age of 6.6 +/- 5.6 years (range, 1.2-13 years), average weight of 36.9 +/- 28.7 kg (range, 9.3-95 kg), and burn size of 43 +/- 21.4% (range, 10-85%). Three children had sustained scald burns and eight had flame injuries with associated inhalation injury. They had been intubated for an average of 12.7 +/- 10.9 (range, 2-33 days). Morphine infusions immediately before the initiation of propofol averaged 0.26 +/- 0.31 mg/kg/hour (range, 0.04-1.29 mg/kg/hr) and midazolam averaged 0.15 +/- 0.16 mg/kg/hr (range, 0.06-0.65 mg/kg/hr). Morphine infusions after beginning propofol and at extubation averaged 0.16 +/- 0.16 (range, 0.04-0.65 mg/kg/hr) and midazolam averaged 0.09 +/- 0.08 mg/kg/hr (range, 0.02-0.32 mg/kg/hr). Propofol doses after initial titration during the first hour of infusion averaged 3.6 +/- 2.9 mg/kg/hr (range, 0.4-8.1 mg/kg/hr). Nine of the 11 children (82%) were successfully extubated on the first attempt. Two required reintubation for postextubation stridor 2 to 6 hours after extubation but were successfully extubated the next day after a short course of steroids, again using the same propofol technique. All were awake at extubation and went on to survive. Morphine and midazolam infusions were gradually weaned, and there were no withdrawal symptoms noted. Although prolonged (days) infusions of propofol have been associated with adverse cardiovascular complications in critically ill young children and should probably be avoided, short-term (in hours) use of the drug can facilitate smooth extubation.

Electroencephalograph variables, drug concentrations and sedation scores in children emerging from propofol infusion anaesthesia

BACKGROUND

Inadequate sedation or oversedation are common problems in Paediatric Intensive Care because of wide variations in drug response and the lack of objective tests for sedative depth. We undertook a pilot study to try to identify correlates of propofol drug concentration, electroencephalographic (EEG) variables and observed behaviour during a stepwise reduction in propofol infusion after paediatric cardiac surgery.

METHODS

This was a prospective pilot study with 10 children (5 months to 8 years) emerging from propofol anaesthesia following cardiac surgery with cardiopulmonary bypass (CPB). Patients underwent a stepped wake-up from propofol anaesthesia during which the propofol infusion rate was decreased from 4 mg.kg(-1).h(-1) in 1 mg.kg(-1).h(-1) steps at 30 min intervals. EEG variables, propofol blood concentrations and clinical sedation scores (COMFORT scale) were recorded during the stepped wakeup. Analgesia was maintained with a standardized continuous infusion of fentanyl.

RESULTS

: Mean (SD) whole blood propofol concentrations at arousal varied considerably [973 ng.ml(-1) (SD 523 ng.ml(-1))]. The summed ratio (SR) of high frequency to low frequency bands correlated with both propofol infusion rate (R2 value=0.47) and propofol blood concentrations (R2 value=0.64). The mean SR in deeply sedated patients was significantly different from that in the 5 min prior to wakening (6.84 vs 1.55, P=0.00002). There was no relationship between COMFORT scores and SR.

CONCLUSIONS

In this group of patients receiving opioid analgesia and relatively high doses of propofol, sedation scores were unhelpful in predicting arousal. The SR correlated with propofol blood concentrations and clinical arousal and may have potential as a predictive tool for arousal in children.

[Total intravenous anesthesia. On the way to standard practice in pediatrics]

Since venous cannulation in children has become easier and extensive experience has been gained with total intravenous anaesthesia (TIVA) in adults, the interest in TIVA for children has recently increased. An intensified sensitivity of the operating room atmosphere to contamination with volatile anaesthetic agents is another important reason to choose intravenous techniques for paediatric anaesthesia. One of the most interesting agents for TIVA in paediatric anaesthesia is propofol. The pharmacokinetic and pharmacodynamic data for modern intravenous drugs is poor. Because the interpatient variability is relatively large, pharmacokinetic data can only provide guidelines for the dosage of propofol. Propofol has a rapid and smooth onset of action and is as easy to titrate in children as in adults. Propofol can be excellently controlled. Severe haemodynamic side-effects are missing in healthy children and plasma is cleared rapidly of propofol by redistribution and metabolism. There is no evidence of significant accumulation, not even after prolonged infusion times. Because propofol has no analgetic properties it must be combined with analgetics or a regional block for all painful procedures. The combination with the ultra-short acting remifentanil is a major advantage, but requires effective analgetic concepts for painful procedures. In comparison the combination of propofol with long acting opioids abolishes some of the favourable properties of propofol. Further studies of the kinetics and dynamics of propofol and other intravenous agents are needed in paediatrics which should focus on age, maturity and severity of illness. The whole importance of the propofol-infusion syndrome has to be cleared up urgently. TIVA has an important significance in paediatric anaesthesia for diagnostic and therapeutic procedures, especially where these have to be repeated. In day-case anaesthesia TIVA has advantages for all short procedures and for ENT and ophthalmic surgery: even after prolonged infusion children have an short recovery time. There is no evidence of agitation or other behavioural disorders after TIVA with propofol in paediatric anaesthesia. Propofol has anti-emetic properties. TIVA with propofol can be combined with regional anaesthesia advantageously to provide long-lasting analgesia after surgery. TIVA with propofol has been used successfully for sedation of spontaneously breathing children for MRI and CT and other procedures with open airways like bronchoscopy or endoscopy. Propofol facilitates endotracheal intubation without the use of muscle relaxants. Of course, in malignant hyperthermia TIVA will continue to be the technique of choice. Nothing is known about awareness under TIVA in paediatric patients. TIVA must be considered by comparison with the volatile agents. The use of ultra-short acting agents may cause problems such as awareness, vagal response, involuntary movements and in some cases slow recovery after prolonged infusion of propofol. But it is not known exactly how often this happens during paediatric anaesthesia. With TIVA an effective postoperative analgesia must be provided. Newer administration techniques such as the target-controlled infusions or closed-loop control systems are under development and will help to minimise the potential risk of overdosage with TIVA in paediatrics. At the present TIVA is an interesting and practicable alternative to volatile anaesthesia for pre-school and school children. TIVA with propofol in infants younger than 1 year old requires extensive experience with TIVA in older children and with the handling of this special age group and should be undertaken with maximum precautionary measures.

Lacticacidosis after short-term infusion of propofol for anaesthesia in a child with osteogenesis imperfecta

We describe the case of a 7-year-old boy with osteogenesis imperfecta, who underwent anaesthesia with propofol-fentanyl-nitrous oxide-suxamethonium for orthopaedic surgery of a distal femur fracture. He developed lacticacidosis after short-term propofol infusion (150 min, mean infusion rate 13.5 mg.kg-1.h-1) associated with a prolonged recovery time without serious haemodynamic changes. The highest lactate concentration was 9.2 mmol.l-1 at 160 min after discontinuation of propofol. There was no significant increase in body temperature. The boy fully recovered.

Cerebrovascular carbon dioxide reactivity in children anaesthetized with propofol

BACKGROUND

Propofol, by virtue of its favourable pharmacokinetic profile, is suitable for maintenance of anaesthesia by continuous infusion during neurosurgical procedures in adults. It is gaining popularity for use in paediatric patients. To determine the effects of propofol on carbon dioxide cerebrovascular reactivity in children, middle cerebral artery blood flow velocity was measured at different levels of endtidal (PECO2) by transcranial Doppler sonography.

METHODS

Ten ASA I or II children, aged 1-6 years undergoing elective urological surgery were enrolled. Anaesthesia comprized propofol aimed at producing an estimated steady-state serum concentration of 3 microg x ml-1 and a caudal epidural block. PECO2 was adjusted randomly in an increasing or decreasing fashion between 3.3, 5.2 and 7.2 kPa (25, 40 and 55 mmHg) with an exogenous source of CO2 while maintaining ventilation parameters constant.

RESULTS

Cerebral blood flow velocity increased as PECO2 increased from 3.3 to 5.2 kPa (25-40 mmHg) (P < 0.001) and from 5.2 to 7.2 kPa (40-55 mmHg) (P < 0.001). Mean heart rate and blood pressure did not change significantly.

CONCLUSIONS

This study demonstrates that cerebrovascular CO2 reactivity is maintained over PECO2 values of 3.3, 5.2 and 7.2 kPa (25, 40 and 55 mmHg) in healthy children anaesthetized with propofol.

Use of propofol infusion in Australian and New Zealand paediatric intensive care units

Despite the risk of propofol infusion syndrome, a rare but often fatal complication of propofol infusion in ventilated children and possibly adults, propofol infusion remains in use in paediatric intensive care units (PICU). This questionnaire study surveys the current pattern of use of this sedative infusion in Australian and New Zealand PICUs. Thirty-three of the 45 paediatric intensive care physicians surveyed (73%), from 12 of the 13 intensive care units, returned completed questionnaires. The majority of practitioners (82%) use propofol infusion in children in PICU, the main indication being for short-term sedation in children requiring procedures. 39% of respondents consider propofol infusion useful in ventilated children requiring longer-term sedation. 67% of paediatric intensivists use maximum infusion doses that may be considered dangerously high (> or = 10 mg/kg/h). Nineteen per cent use propofol infusion for prolonged periods (> 72 hours). A smaller proportion (15%) of respondents indicate that they may use both higher doses and prolonged periods of infusion, a practice likely to lead to a greater chance of serious adverse events. Knowledge of local protocols for the use of propofol infusion is associated with a significantly greater level of monitoring for possible adverse events. We suggest that national guidelines for the use of propofol infusion in children should be developed. These should include clear indications and contraindications to its use, a maximum dose rate and maximum period of infusion, with a ceiling placed on the cumulative dose given and clearly stated minimum monitoring requirements.

Continuous propofol infusion in 142 critically ill children

OBJECTIVE

In recent years, continuous intravenous propofol infusion has been widely used in pediatric intensive care units. Several case reports have raised concerns about its safety. The objective of this study was to report our experience with continuous intravenous propofol in consecutive patients during an 18-month period.

METHODS

The study design was a retrospective review of a case series. Case was defined as a critically ill child who was treated with continuous intravenous propofol. The attending physician staff agreed to prescribe propofol via continuous intravenous infusion at a dose not to exceed 50 microg/kg/min. The protocol allowed for each patient to receive an additional intravenous bolus of propofol at a dose of 1 mg/kg no more than once per hour. The study entailed data collection from consecutive patients who were prescribed a continuous infusion of propofol in either the pediatric intensive care unit or bone marrow transplant unit.

RESULTS

Data from 142 patients were analyzed. Each patient enrolled was adequately sedated. Administration of propofol via continuous intravenous infusion was not associated with metabolic acidosis or hemodynamic compromise. No patient in the study group was inadvertently extubated or had a central venous catheter accidentally discontinued.

CONCLUSIONS

Propofol can be safely and effectively used to provide sedation to critically ill infants and children. We speculate that continuous infusion of propofol for extended periods of time should not exceed 67 microg/kg/min.

Pharmacokinetics and effects of propofol 6% for short-term sedation in paediatric patients following cardiac surgery

AIMS

This paper describes the pharmacokinetics and effects of propofol in short-term sedated paediatric patients.

METHODS

Six mechanically ventilated children aged 1-5 years received a 6 h continuous infusion of propofol 6% at the rate of 2 or 3 mg kg-1 h-1 for sedation following cardiac surgery. A total of seven arterial blood samples was collected at various time points during and after the infusion in each patient. Pharmacokinetic modelling was performed using NONMEM. Effects were assessed on the basis of the Ramsay sedation score as well as a subjective sedation scale.

RESULTS

The data were best described by a two-compartment pharmacokinetic model. In the model, body weight was a significant covariate for clearance. Pharmacokinetic parameters in the weight-proportional model were clearance (CL) = 35 ml kg-1 min-1, volume of central compartment (V1) = 12 l, intercompartmental clearance (Q) = 0.35 l min-1 and volume of peripheral compartment (V2) = 24 l. The interindividual variabilities for these parameters were 8%, < 1%, 11% and 35%, respectively. Compared with the population pharmacokinetics in adults following cardiac surgery and when normalized for body weight, statistically significant differences were observed the parameters CL and V1 (35 vs 29 ml kg-1 min-1 and 0.78 vs 0.26 l kg-1P < 0.05), whereas the values for Q and V2 were similar (23 vs 18 ml kg-1 min-1 and 1.6 vs 1.8 l kg-1, P > 0.05). In children, the percentage of adequately sedated patients was similar compared with adults (50% vs 67%) despite considerably higher propofol concentrations (1.3 +/- 0.10 vs 0.51 +/- 0.035 mg l-1, mean +/- s.e. mean), suggesting a lower pharmacodynamic sensitivity to propofol in children.

CONCLUSIONS

In children aged 1-5 years, a pharmacokinetic model for propofol was described using sparse data. In contrast to adults, body weight was a significant covariate for clearance in children. The model may serve as a useful basis to study the role of covariates in the pharmacokinetics and pharmacodynamics of propofol in paediatric patients of different ages.

Propofol decreases cerebral blood flow velocity in anesthetized children

PURPOSE

Propofol, by virtue of its favourable pharmacokinetic profile, is suitable for maintenance of anesthesia by continuous infusion during neurosurgical procedures in adults. It is gaining popularity for use in pediatric patients. To determine the effects of propofol on cerebral blood flow in children, middle cerebral artery blood flow velocity (Vmca) was measured at different levels of propofol administration by transcranial Doppler (TCD) sonography.

METHODS

Twelve ASA I or II children, aged one to six years undergoing elective urological surgery were randomized to receive one of two propofol dosing regimens. Half of the patients received propofol in an escalating fashion, initially targeting an estimated steady-state serum concentration of 3 microg x mL-1, which was then doubled. The other half received propofol designed initially to target the high concentration followed by the lower one. In each child anesthesia was induced and maintained with propofol according to the protocol, rocuronium was given to facilitate tracheal intubation, and a caudal epidural block was performed. A TCD probe was placed appropriately to measure Vmca. Cerebral blood flow velocity (CBFV), mean arterial pressure (MAP) and heart rate (HR) were recorded simultaneously at both levels of propofol administration.

RESULTS

Twelve patients were studied. At the higher estimated target serum propofol concentration there were significant decreases in Vmca (17%, P < 0.001), MAP (6%, P < 0.002) and HR (8%, P < 0.05) when compared to the lower targeted concentration.

CONCLUSION

This study shows that a higher rate of propofol infusion is associated with lower CBFV and MAP values in children. Propofol's cerebral vasoconstrictive properties may be responsible for this finding.

The propofol infusion syndrome in infants and children: can we predict the risk?

Propofol has been an immensely successful anaesthetic induction agent but there is an increasing number of reports of serious complications when it has been used as an infusion to provide sedation for prolonged periods. The first reports involved children who died from intractable myocardial failure preceded by a metabolic acidosis, lipaemic plasma, fatty infiltration of the liver and evidence of muscle damage. As more cases have been reported the association between propofol and the syndrome has become more certain. Recently adult cases have appeared and a metabolic explanation has been suggested. The syndrome has a high mortality and the only effective treatment appears to be dialysis.

An item analysis of the COMFORT scale in a pediatric intensive care unit

OBJECTIVE: The objective of this study was to conduct an item analysis of the COMFORT scale within a sample of critically ill children. The COMFORT scale is a tool that measures eight clinical parameters at the bedside to determine a critically ill child's level of distress. However, documentation of the reliability and validity of specific components of this instrument has been limited to date. DESIGN: This was an observational study. SETTING: A tertiary care pediatric intensive care unit. PATIENTS: A sample of 18 intubated, mechanically ventilated patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: An item analysis of the COMFORT scale was conducted. The scale was used for variable intervals with each child, providing a total of 514 individual completed ratings. These ratings were then submitted to descriptive, correlational, factor, and regression analyses using the Statistical Package for the Social Sciences. The principal finding of this item analysis was that 97% of the total score variance was explained by six of the eight items. In particular, it was remarkable that heart rate and blood pressure demonstrated very limited reliability and validity as determinants of the total COMFORT score. As well, the clinical experience of the investigators with this scale has demonstrated that these two items can be cumbersome to use, given that these parameters are often affected by hemodynamic factors. CONCLUSIONS: On the basis of these findings, we propose a modified COMFORT scale based on a six-item scoring system. This modified scale would provide a more reliable and valid measure for research as well as clinical purposes, by eliminating two parameters that can be affected by factors other than the child's level of distress.

Propofol compared with general anesthesia for pediatric GI endoscopy: is propofol better?

BACKGROUND

The objective of this study was to compare the efficacy and safety of propofol and general anesthesia in children undergoing elective GI endoscopy.

METHODS

The study design was prospective, randomized, and open label. Pediatric patients aged 2 to 21 years in whom elective GI endoscopy under general anesthesia was required were randomized to receive propofol or standard inhalational anesthesia. The parameters monitored in the 2 groups were (1) time until wake-up after completion of the procedure, and (2) total time for anesthesia and recovery. Adverse events during the procedures were noted with each agent.

RESULTS

Fifty pediatric patients were recruited, 25 in each group. The mean (SD) time until wake-up in the propofol group was 29.92 (16.01) minutes and 18.52 (10.03) minutes in the anesthesia group, (p = 0.002). With stratification into 4 age groups, it was noted that the youngest children, those 2 to 5 years of age, took the longest to awaken with propofol compared with inhalational anesthesia, whereas in the other age groups the differences were not statistically significant. In contrast, the mean total time for anesthesia and recovery in the propofol group was 107.4 (30.14) minutes and 139 (7.61) minutes in the inhalational anesthesia group (p < 0.004). The total time for anesthesia and recovery was longest in the group 5 to 8 years of age who had inhalational anesthesia (p < 0.01). Changes in systolic and diastolic blood pressure occurred with equal frequency in both groups. Transient apnea was noted in 20% of patients receiving propofol. Restlessness and agitation occurred in 52% of patients receiving inhalational anesthesia compared with 8% in the propofol group (p = 0.001).

CONCLUSIONS

Propofol, administered by an anesthesiologist, is an excellent and safe intravenous anesthetic agent for pediatric GI endoscopy.

Pain management in the critically ill child

Children frequently received no treatment, or inadequate treatment, for pain and for painful procedures. The newborn and critically ill children are especially vulnerable to no treatment or under-treatment. Nerve pathways essential for the transmission and perception of pain are present and functioning by 24 weeks of gestation. The failure to provide analgesia for pain results in rewiring the nerve pathways responsible for pain transmission in the dorsal horn of the spinal cord and results in increased pain perception for future painful results. Many children would withdraw or deny their pain in an attempt to avoid yet another terrifying and painful experiences, such as the intramuscular injections. Societal fears of opioid addiction and lack of advocacy are also causal factors in the under-treatment of pediatric pain. False beliefs about addictions and proper use of acetaminophen and other analgesics resulted in the failure to provide analgesia to children. All children even the newborn and critically ill require analgesia for pain and painful procedures. Unbelieved pain interferes with sleep, leads to fatigue and a sense of helplessness, and may result in increased morbidity or mortality.

Sedation-analgesia in the pediatric intensive care unit

The provision of sedation and analgesia is an integral aspect of the care of PICU patients. A careful systems approach to the provision of sedation and analgesia can minimize complications and maximize benefit to patients. Vigilance in monitoring and adherence to published guidelines are important for safety. Physicians must define the goals in clearly devising a plan and tailor the prescription to those goals rather than use a regimented protocol for all patients.

The reliability and validity of the COMFORT scale as a postoperative pain instrument in 0 to 3-year-old infants

The aim of this study was to test the reliability and validity of the COMFORT scale as a postoperative pain instrument for children aged 0-3 years. Subjects were 158 neonates and toddlers after major abdominal or thoracic surgery. Trained nurses rated the children's pain at 3, 6 and 9 h postoperative on the Pediatric Surgical Intensive Care Unit using the COMFORT and a VAS for pain. Interrater reliability of the COMFORT items proved to be good (Kappa 0.63-0.93) for all items with the exception of the item 'Respiratory response', which was moderate (Kappa 0.54). LISREL analyses showed that the structure of the COMFORT data was best represented by three latent variables: COMFORT 'behaviour' with loadings from the behavioural items (Alertness, Calmness, Respiratory response/Crying, Physical movement, Muscle tone and Facial tension) and separate latent variables for 'Heart rate baseline' (HR) and 'Mean arterial blood pressure baseline' (MAP). Factor loadings of the items were invariant across time, indicating stability of the structure. The latent variables COMFORT 'behaviour' and VAS pain were highly interrelated indicating congruent validity. Stability of COMFORT 'behaviour' and VAS pain was moderate which might be due to varying painful episodes in this sample. HR and MAP, although stable across time, were weakly related to VAS pain and COMFORT 'behaviour'. These findings support the use of the COMFORT 'behaviour' scale to assess postoperative pain in neonates and infants.

Procedural anesthesia at the bedside

Procedural anesthesia at the bedside offers patients relief from anxiety, discomfort, and pain and may expedite the procedure by increasing patient cooperation. Prospective planning requires knowledge of the condition of the patient and an assessment of the anesthetic requirements of the proposed procedure. The spectrum of anesthetic options includes sedation and analgesia, monitored anesthesia care, to total intravenous anesthesia (see Fig. 1). Identification of the at-risk patient and modifying the anesthetic should reduce complications (see Box 3). The choice of pharmaceuticals varies depending on the level of anticipated anesthesia. Personnel requirements also vary. Although an anesthesiologist is not required to administer medications and monitor the patient for sedation and analgesia or monitored anesthesia care, TIVA requires the services of an anesthesiologist. Costs are influenced by the personnel requirements and length of the procedure, which sets the drug requirements and drug costs. In the end, personal experience combined with knowledge should guide the provider to offer efficacious and cost-effective procedural anesthesia in the ICU.

Propofol reduces the migration of human leukocytes through endothelial cell monolayers

OBJECTIVE

To test propofol and the solvent of propofol on leukocyte function in the presence of endothelial cell monolayers. The interactions of leukocytes with endothelial cells play a tremendous role during inflammation. Previous studies have investigated the influence of propofol on leukocytes.

DESIGN

Prospective, controlled study.

SETTING

University research laboratories.

SUBJECTS

Seven independent experiments were performed to investigate the influence of propofol (0.4, 4, and 40 ng/mL) on the migration of human leukocytes through human endothelial cell monolayers. Moreover, the authors tested the solvent of propofol on leukocyte migration.

INTERVENTIONS

Human endothelial cell monolayers and/or human leukocytes were preincubated with clinically relevant higher and lower concentrations of propofol. The amount of leukocyte migration after 3 hrs was measured with a fluorometer.

MEASUREMENTS AND MAIN RESULTS

Human endothelial cells isolated from umbilical veins were cultured on microporous membranes until they formed an endothelial cell monolayer. Leukocytes were separated by standard procedures. The migration of leukocytes through monolayers of endothelial cells using the clinically relevant concentration of propofol was reduced to 93% +- 3.8% (so; p < .05) when the leukocytes but not the endothelial cell monolayers were preincubated with propofol. Leukocyte migration was reduced to 80% - 5.9% (p < .05) when only monolayers of endothelial cells were treated with propofol, and was reduced to 73% + 10.4% (p < .05) when both leukocytes and monolayers of endothelial cells were treated with propofol. The higher and lower concentrations showed a dose-dependent effect. The solvent of propofol had no significant effect.

CONCLUSION

The authors investigated the influence of propofol and its solvent on the interaction between both cell systems-leukocytes and endothelial cells. Propofol is able to reduce significantly the migration of leukocytes through endothelial cell monolayers. The use of different doses revealed a dose-dependent effect. The current model allowed treatment of one cell type: leukocyte or endothelial cell. The results of this investigation indicate that the influence of propofol on leukocyte migration affects endothelial cells more than leukocytes.

Propofol infusion syndrome in children

The use of propofol infusions to sedate children in intensive care units has decreased after reports of deaths from myocardial failure. More recently it has been suggested that propofol might have been prematurely condemned. Information about 18 children who had received propofol infusions and suffered serious unwanted effects was used to define their common features. Three of the deaths occurred in one intensive care unit where propofol infusions had been used between 1987 and 1993. During this period 44 children with respiratory tract infections had been admitted to this unit and sedated for at least 48 h. Nine had received long-term (> 48 h), high-dose (> 4 mg.kg-1.h-1) propofol infusions and three had developed progressive myocardial failure and died. There was a significant association between receiving a long-term, high-dose propofol infusion and developing progressive myocardial failure (Fisher's Exact Test, two-tailed hypothesis, P = 0.0128) although a causative relationship could not be proved.

Lactic acidemia and bradyarrhythmia in a child sedated with propofol

OBJECTIVES

To describe a severe adverse reaction in a child who received an infusion of propofol for sedation in the intensive care unit (ICU). To describe the management and further investigation of this patient and review similar published reports.

DESIGN

Case report and literature review.

SETTING

Community hospital ICU and tertiary pediatric ICU.

PATIENT

Infant with upper respiratory obstruction secondary to an esophageal foreign body who required tracheal intubation and mechanical ventilation.

INTERVENTIONS

Conventional cardiovascular and respiratory support. Continuous veno-venous hemofiltration (CVVH) and plasmapheresis.

MEASUREMENTS AND MAIN RESULTS

The patient received a propofol infusion at a mean rate of 10 mg/kg/hr for 50.5 hrs. He developed lipemia and green urine and subsequently, a progressive severe lactic acidemia and bradyarrhythmias unresponsive to conventional treatment. These abnormalities resolved with CVVH. He was encephalopathic and developed liver and muscle necrosis histologically compatible with a toxic insult. Examination of homogenized muscle tissue demonstrated a reduction in cytochrome C oxidase activity. There was no evidence of systemic infection or underlying metabolic disease. He eventually recovered completely.

CONCLUSION

Propofol has been associated with severe adverse reactions in children receiving intensive care. The biochemical and histologic abnormalities described in this patient may guide further investigation. We advise against prolonged use of propofol for sedation in children.

The pediatric sedation unit: a mechanism for pediatric sedation

OBJECTIVES

We have created a pediatric sedation unit (PSU) in response to the need for uniform, safe, and appropriately monitored sedation and/or analgesia for children undergoing invasive and noninvasive studies or procedures in a large tertiary care medical center. The operational characteristics of the PSU are described in this report, as is our clinical experience in the first 8 months of operation.

METHODS

A retrospective review of quality assurance data was performed. These data included patient demographics and chronic medical diagnoses, procedure, or study performed; sedative or analgesic medication given; complications (defined prospectively); and sedation and monitoring time. Patient-specific medical records related to the procedure and sedation were reviewed if a complication was noted in the quality assurance data.

RESULTS

Briefly, the PSU was staffed with an intensivist and pediatric intensive care unit nurses. Patients were admitted to the PSU and assessed medically for risk factors during sedation. Continuous heart rate, respiratory rate, and pulse oximetry monitoring were used, and blood pressure was determined every 5 minutes. After sedation and stabilization, with monitoring continued, the patient was transported to the site to undergo the procedure or study. The pediatric intensive care unit nurse remained with the patient at all times. All necessary emergency equipment was transported with the patient. After the procedure or study was completed, the patient was returned to the PSU for recovery to predetermined parameters. We were able to analyze 458 episodes of sedation for this review. Procedures and studies included radiologic examinations, cardiac catheterization, orthopedic manipulations, solid organ and bone marrow biopsy, gastrointestinal endoscopy, bronchoscopy, evoked potential measurements, and others. Patients were 2 weeks to 32 years of age. The average time from initiation of sedation to last dose of medication administered was 84 minutes. The average time from initiation of sedation to full recovery was 120 minutes. Sedative and analgesia medications use was not standardized; however, the majority of children needing sedation received propofol or midazolam. For patients requiring analgesia, ketamine or fentanyl was added. In 79 of 458 (12%) sedation episodes, complications were documented. Mild hypotension (4.4%), pulse oximetry <93% (2.6%), apnea (1.5%), and transient airway obstruction (1.3%) were the most common complications noted. Cancellation of 11 (2.4%) procedures was attributable to complications. No long-term morbidity or mortality was seen.

CONCLUSIONS

Many children require sedation or analgesia during procedures or studies. Safe sedation is best ensured by appropriate presedation risk assessment and with monitoring by a care provider trained in resuscitative measures who is not involved in performing the procedure itself. Uniformity of care in a large institution is a standard met by the creation of a centralized service, with active input from the department of anesthesiology. We present the PSU as a model for achieving these goals.

Convulsions, ataxia and hallucinations following propofol

A 6-year-old fit girl experienced convulsions 44 h after an otherwise uneventful anaesthesia with propofol, alfentanil and nitrous oxide. As an underlying pathology was suspected, the child was kept sedated for 6.5 h for further investigations. During this period she received a continuous infusion of propofol amounting in total to 1600 mg. After having regained consciousness, she was strikingly ataxic and remained so for 5 days. During this period she also experienced two episodes of hallucinations lasting about 2 h. Investigations including lumbar puncture, EEG, cerebral CT and MR scan could not explain the neurological symptoms. She recovered without long-term sequelae.