Short-term propofol infusions in children

Propofol Sedation Washouts in Critically Ill Infants: A Case Series

Medically complex infants are experiencing longer hospital stays, more invasive procedures, and increasingly involved therapeutic interventions that often require long-term analgesia and sedation. This is most commonly achieved with continuous intravenous infusions of opioids and benzodiazepines. There are times when patients develop a tolerance for these medications or the clinical scenario necessitates a rapid wean of them. A rapid wean of either class of medication can lead to increased signs of pain and agitation or withdrawal symptoms. As a result, when a rapid wean is needed or there has been a failure to control symptoms with conventional measures, alternative therapies are considered. Propofol, a sedative hypnotic typically used for general anesthesia and procedural sedation, is one such medication. It has effectively been used for short-term sedation in adults and children to facilitate weaning benzodiazepines and opioids. There is a paucity of data on the use of propofol in infants for this purpose. Here we describe the use of propofol to rapidly wean high-dose sedation and analgesia medications, a propofol sedation washout, in 3 infants. The washouts proved to be safe and efficacious. Based on institutional experience and a literature review, considerations and recommendations are made for propofol sedation washouts in infants.

Refractory atrial fibrillation with rapid ventricular response as a heralding sign of propofol infusion syndrome in a patient with COVID-19

A woman in her 40s was transferred to the medical intensive care unit due to severe COVID-19 infection causing respiratory failure. Her respiratory failure worsened rapidly, requiring intubation and continuous sedation with fentanyl and propofol infusions. She required progressive increases in the rates of the propofol infusion, as well as addition of midazolam and cisatracurium due to ventilator dyssynchrony. To support the high sedative doses, norepinephrine was administered as a continuous infusion. She developed atrial fibrillation with rapid ventricular response, with rates ranging between 180 and 200 s which did not respond to intravenous adenosine, metoprolol, synchronised cardioversion or amiodarone. A blood draw revealed lipaemia, and triglyceride levels were noted to be elevated to 2018. The patient developed high-grade fevers up to 105.3 and acute renal failure with severe mixed respiratory and metabolic acidosis, indicating propofol-related infusion syndrome. Propofol was promptly discontinued. An insulin-dextrose infusion was initiated which improved patient's fevers and hypertriglyceridaemia.

Propofol toxicity in the developing mouse heart mitochondria

BACKGROUND

Propofol infusion syndrome (PRIS) is a potentially lethal consequence of long-term propofol administration. Children are vulnerable and cardiac involvement is often prominent and associated with mortality. We aimed to determine the mechanism of propofol toxicity in newborn mice, hypothesizing that propofol would induce discrete defects within immature cardiac mitochondria.

METHODS

Newborn murine cardiac mitochondria were exposed to propofol or intralipid in vitro. Non-exposed mitochondria served as controls. Mitochondrial respiration and membrane potential (ΔΨ) were measured and respiratory chain complex kinetics were determined.

RESULTS

Propofol and intralipid exerted biological activity in isolated mitochondria. Although intralipid effects were a potential confounder, we found that propofol induced a dose-dependent increase in proton leak and caused a defect in substrate oxidation at coenzyme Q (CoQ). These impairments prevented propofol-exposed cardiomyocyte mitochondria from generating an adequate ΔΨ. The addition of the quinone analog, CoQ₀, blocked propofol-induced leak and increased Complex II+III activity.

CONCLUSIONS

Propofol uncoupled immature cardiomyocyte mitochondria by inducing excessive CoQ-sensitive leak and interfered with electron transport at CoQ. The findings provide new insight into the mechanisms of propofol toxicity in the developing heart and may help explain why children are vulnerable to developing PRIS.

IMPACT

Propofol uncouples immature cardiomyocyte mitochondria by inducing excessive coenzyme Q (CoQ)-sensitive proton leak. Propofol also interferes with electron transport at the level of CoQ. These defects provide new insight into propofol toxicity in the developing heart.

The effects of anaesthetics and sedatives on brain inflammation

Microglia are involved in many dynamic processes in the central nervous system (CNS) including the development of inflammatory processes and neuromodulation. Several sedative, analgesic or anaesthetic drugs, such as opioids, ∝2-adrenergic agonists, ketamine, benzodiazepines and propofol can cause both neuroprotective and harmful effects on the brain. The purpose of this review is to present the main findings on the use of these drugs and the mechanisms involved in microglial activation. Alpha 2-adrenergic agonists, propofol and benzodiazepines have several pro- or anti-inflammatory effects on microglia. Long-term use of benzodiazepines and propofol causes neuroapoptotic effects and α2-adrenergic agonists may attenuate these effects. Conversely, morphine and fentanyl may have proinflammatory effects, causing behavioural changes in patients and changes in cell viability in vitro. Conversely, chronic administration of morphine induces CCL5 chemokine expression in microglial cells that promotes their survival.

The Basic Study of the Mechanism of Propofol-Related Infusion Syndrome Using a Murine Skeletal Muscle Injury Model

Background

The pathophysiological mechanism of propofol-related infusion syndrome (PRIS) is believed to be due to the injury to the mitochondrial electron transport chain and the resultant metabolic disorders that are caused by both propofol agents and the lipid solvent. However, the mechanisms and causative factors of PRIS have not been fully elucidated.

Objectives

The aim of this study was to evaluate the possibility of a research model using the culture of differentiated C2C12 cells for fundamental research of PRIS.

Methods

First, differentiated C2C12 cells were cultured accompanied by several concentrations of chemical reagents of 2,6-diisopropylphenol (2,6 DIP) or dimethyl sulfoxide (DMSO) for 60 hours and the cell death rate was examined by trypan blue staining. Second, The cells were incubated with a commercially available propofol reagent or lipid reagent for 48 hours. The supernatant fluid of the cell culture medium was gathered and the numbers of floating cells were measured by cell counter. To investigate the mitochondrial disorder by the propofol preparation, JC-1, an experiment using fluorescent reagent, was performed for the 48 hours with 100 µg/mL propofol incubation.

Results

The rate of cell death was increased with elevating concentrations both of chemical reagents of 2,6 DIP group and dimethyl sulfoxide group. The rates of cell death were significantly higher in the 2,6 DIP group than DMSO group. The numbers of floating cells were increased with elevating concentrations both commercially available propofol reagent and lipid reagent groups. The decreased red/green fluorescence ratio by JC-1 staining in the propofol 100µg/mL group proved an attenuated mitochondrial membrane potential.

Conclusions

The dose-dependent cell damage induced by the propofol reagents and a lipid solvent may provide a proposed model as a basic experimental model for further investigations into PRIS.

Practicalities of Total Intravenous Anesthesia and Target-controlled Infusion in Children

Propofol administered in conjunction with an opioid such as remifentanil is used to provide total intravenous anesthesia for children. Drugs can be given as infusion controlled manually by the physician or as automated target-controlled infusion that targets plasma or effect site. Smart pumps programmed with pharmacokinetic parameter estimates administer drugs to a preset plasma concentration. A linking rate constant parameter (keo) allows estimation of effect site concentration. There are two parameter sets, named after the first author describing them, that are commonly used in pediatric target-controlled infusion for propofol (Absalom and Kataria) and one for remifentanil (Minto). Propofol validation studies suggest that these parameter estimates are satisfactory for the majority of children. Recommended target concentrations for both propofol and remifentanil depend on the type of surgery, the degree of surgical stimulation, the use of local anesthetic blocks, and the ventilatory status of the patient. The use of processed electroencephalographic monitoring is helpful in pediatric total intravenous anesthesia and target-controlled infusion anesthesia, particularly in the presence of neuromuscular blockade.

Recovery with Propofol Anesthesia in Children Undergoing Cleft Palate Repair Compared with Sevoflurane Anesthesia

Background

Nowadays, propofol total intravenous anesthesia (propofol TIVA) is a very attractive choice for routine pediatric anesthesia practice.

Objectives

To compare propofol- vs. sevoflurane-based anesthesia for pediatrics undergoing cleft palate repair in emergence characteristics and respiratory adverse effects.

Methods

Eighty infants, aged from six months to one year, scheduled for cleft palate repair surgery, were randomly divided into two groups (40 patients each). The group I received general anesthesia induced with intravenous propofol 2.5 mg/kg, 0.1 mg/kg of lidocaine, fentanyl one µg/kg and cisatracurium 0.15 mg/kg, and maintained by a continuous infusion of propofol 9 mg/kg/hr and cisatracurium 3 µg/kg/hr. While in the group II, general anesthesia induced by O₂/sevoflurane, intravenous fentanyl one µg/kg and cisatracurium 0.15 mg/kg then the maintenance was carried out by O₂/air, sevoflurane 2 MAC, and cisatracurium three µg/kg/hr. Postoperative FLACC behavioral pain assessment Scale, modified Hannallah score, postoperative laryngeal spasm incidence, the recovery time, time to extubation, and postoperative complication were recorded.

Results

The quality of emergence was assessed by modified Hannallah score, there was a significant decrease in the number of patients developed agitation after propofol TIVA in comparison to sevoflurane anesthesia (P < 0.001) with a significant decrease in the number of patients developed postoperative laryngeal spasm (P < 0.047). On the other hand, a significantly prolonged time of extubation was observed in the propofol TIVA group (P < 0.001).

Conclusions

Propofol TIVA regimen was the more peaceful recovery approach with less perioperative respiratory complications than sevoflurane-based anesthesia in infants undergoing cleft palate repair surgery.

A follow-up survey of total intravenous anesthesia usage in children in the U.K. and Ireland

BACKGROUND

Total intravenous anesthesia usage in children remains relatively unpopular in the UK and Ireland. A postal survey by Hill et al in 2008 indicated that only 26% of Consultants used a propofol infusion at least once a month.

AIMS

Following an increase in teaching and training opportunities in pediatric total intravenous anesthesia in the UK, we repeated the survey among Consultant members of Association of Paediatric Anaesthetists of Great Britain and Ireland and Society for Intravenous Anaesthesia, to see if this had affected total intravenous anesthesia usage in children and how practice may have changed.

METHODS

We used an anonymous online survey sent to Association of Paediatric Anaesthetists of Great Britain and Ireland and Society for Intravenous Anaesthesia members.

RESULTS

A total of 291 responses were analyzed. Total intravenous anesthesia was the default method of anesthesia in 8% of respondents and a further 46% used total intravenous anesthesia at least monthly. Overall total intravenous anesthesia usage had increased in the past year in 53%. The main indications were malignant hyperthermia susceptibility, and postoperative nausea and vomiting. Ear/nose/throat surgery was the most popular surgical specialty. The main reasons for not using total intravenous anesthesia were that it was too "fiddly" and lack of confidence in the user. Most respondents used propofol in combination with remifentanil. Over 80% used propofol target-controlled infusion. The potential for propofol-related infusion syndrome concerned many, with 74% limiting infusion duration as a result. Bispectral Index was not used routinely by the majority of anesthetists. Even though most anesthetists did not use total intravenous anesthesia routinely, 98% felt they would be confident to anesthetize an malignant hyperpyrexia-positive patient using the technique.

CONCLUSION

This survey has shown that although total intravenous anesthesia is not the default anesthetic technique for most anesthetists, overall usage in children has more than doubled in the past 10 years, with many happy to use it in a wide variety of patients and procedures.

Short-Term Low-Dose Propofol Anaesthesia Associated with Severe Metabolic Acidosis

Propofol-induced metabolic acidosis is well recognised in the paediatric literature, but the existence of such a syndrome in adults remains contentious. In most reported cases, metabolic acidosis complicated prolonged administration of propofol in critically ill patients. We present a case of severe non-fatal reversible metabolic acidosis, without ventilatory depression or hypoxia, related to short-term propofol infusion in an adult during and after coronary artery bypass grafting. We suggest that lactic acidosis occurred in a genetically susceptible patient with an abnormality of mitochondrial function. This report discusses an unusual adverse effect of propofol anaesthesia and sedation and highlights the need for further investigation to define propofol toxicity.

Short-Term Propofol Infusion and Associated Effects on Serum Lactate in Pediatric Patients

OBJECTIVES

This study aimed to determine if short-duration procedural sedation in children with propofol is related to an adverse metabolic stress response measured by serum lactate. Propofol infusion syndrome is associated with high-dose and long-duration infusion. It has not been studied with short-duration, outpatient propofol administration.

METHODS

This was a prospective, longitudinal study that included 50 patients between the ages of 2 and 18 years who were undergoing outpatient procedural sedation with propofol at a pediatric sedation unit. Patients received bolus or bolus and continuous infusion doses of propofol. Serum lactate values were obtained before and after the patients' sedated procedures.

RESULTS

The average length of procedure was 40.3 minutes, and the mean dose of propofol per patient was 8.2 mg/kg. The highest measured lactate value was 1.8 mmol/L. The average (SD) preprocedure and postprocedure lactate values were 1.0 (0.3) and 0.7 (0.2) mmol/L, respectively, resulting in an overall significant decrease in lactate of -0.3 (0.3) mmol/L (P < 0.001). There was a significant (P = 0.01) positive relationship between age and postprocedure lactate value, when controlling for the length of the procedure in a multivariable regression. No significant association was found between propofol dosage and length of the procedure with lactate values.

CONCLUSION

In this study, we did not find a significant increase in metabolic stress, measured by serum lactate. Using propofol for short-duration procedural sedation may not carry similar risks for propofol infusion syndrome to those for long-duration/high-dose infusion therapy.

Evaluation of methohexital as an alternative to propofol in a high volume outpatient pediatric sedation service

BACKGROUND

Propofol is a preferred agent for many pediatric sedation providers because of its rapid onset and short duration of action. It allows for quick turn around times and enhanced throughput. Occasionally, intravenous (IV) methohexital (MHX), an ultra-short acting barbiturate is utilized instead of propofol.

OBJECTIVE

Describe the experience with MHX in a primarily propofol driven outpatient sedation program and to see if it serves as an acceptable alternative when propofol is not the preferred pharmacologic option.

METHODS

Retrospective chart review from 2012 to 2015 of patients receiving IV MHX as their primary sedation agent. Data collected included demographics, reason for methohexital use, dosing, type of procedure, success rate, adverse events (AE), duration of the procedure, and time to discharge.

RESULTS

Methohexital was used in 240 patient encounters. Median age was 4years (IQR 2-7), 71.8% were male, and 80.4% were ASA-PS I or II. Indications for MHX use: egg+soy/peanut allergy in 93 (38.8%) and mitochondrial disorder 9 (3.8%). Median induction bolus was 2.1mg/kg (IQR, 1.9-2.8), median maintenance infusion was 4.5mg/kg/h (IQR, 3.0-6.0). Hiccups 15 (6.3%), secretions requiring intervention 14 (5.8%), and cough 12 (5.0%) were the most commonly occurring minor AEs. Airway obstruction was seen in 28 (11.6%). Overall success rate was 94%. Median time to discharge after procedure completion was 40.5min (IQR 28-57).

CONCLUSION

Methohexital can be used with a high success rate and AEs that are not inconsistent with propofol administration. Methohexital should be considered when propofol is not a preferred option.

Propofol Is Mitochondrion-Toxic and May Unmask a Mitochondrial Disorder

There are indications that preexisting mitochondrial disorders or beta-oxidation defects predispose for propofol infusion syndrome. This review aimed at investigating if propofol infusion syndrome occurs exclusively in patients with mitochondrial disorder and if propofol can unmask a mitochondrial disorder. Propofol infusion syndrome has been reported in genetically confirmed mitochondrial disorder patients. In addition, muscle biopsy of patients with propofol infusion syndrome revealed complex IV or complex II deficiency. In animal studies propofol disrupted the electron flow along the respiratory chain and decreased complex I, complex II, and complex III of the respiratory chain. In addition, propofol disrupted the permeability transition pore and reduced the mitochondrial membrane potential. In conclusion, propofol is mitochondrion-toxic and mitochondrial disorder patients should not receive propofol in high dosages over a prolonged period of time. Short-term application of propofol should be safe even in mitochondrial disorder patients. Not only does propofol infusion syndrome occur in mitochondrial disorder patients, but mitochondrial disorder patients are likely at higher risk to develop propofol infusion syndrome. Patients who develop propofol infusion syndrome should be screened for mitochondrial disorder. Propofol infusion syndrome is preventable if risk factors are thoroughly assessed, and if long-term propofol is avoided in patients at risk for propofol infusion syndrome.

Potential factors involved in the causation of rhabdomyolysis following status asthmaticus

Rhabdomyolysis is a rare but potentially fatal complication of status asthmaticus. Since the first case was reported in 1978, only a few dozen cases have been described till date. We performed a literature review with the aim to characterize the pathophysiological basis of the occurrence of rhabdomyolysis in patients with status asthmaticus. Excessive exertion of respiratory muscles, hypoxia and acidosis, electrolyte imbalance, infections, some drugs used for asthma control, use of mechanical ventilation, prolonged cardiopulmonary resuscitation, higher age of the patient and some underlying diseases or genetic factors appear to be involved in its causation. In patients with status asthmaticus, it is important to pay more attention to these factors and to closely monitor creatine kinase levels in blood so as to ensure early detection of rhabdomyolysis.

Propofol infusion syndrome: a structured review of experimental studies and 153 published case reports

INTRODUCTION

Propofol infusion syndrome (PRIS) is a rare, but potentially lethal adverse effect of a commonly used drug. We aimed to review and correlate experimental and clinical data about this syndrome.

METHODS

We searched for all case reports published between 1990 and 2014 and for all experimental studies on PRIS pathophysiology. We analysed the relationship between signs of PRIS and the rate and duration of propofol infusion causing PRIS. By multivariate logistic regression we looked at the risk factors for mortality.

RESULTS

Knowledge about PRIS keeps evolving. Compared to earlier case reports in the literature, recently published cases describe older patients developing PRIS at lower doses of propofol, in whom arrhythmia, hypertriglyceridaemia and fever are less frequently seen, with survival more likely. We found that propofol infusion rate and duration, the presence of traumatic brain injury and fever are factors independently associated with mortality in reported cases of PRIS (area under receiver operator curve = 0.85). Similar patterns of exposure to propofol (in terms of time and concentration) are reported in clinical cases and experimental models of PRIS. Cardiac failure and metabolic acidosis occur early in a dose-dependent manner, while arrhythmia, other electrocardiographic changes and rhabdomyolysis appear more frequently after prolonged propofol infusions, irrespective of dose.

CONCLUSION

PRIS can develop with propofol infusion <4 mg/kg per hour and its diagnosis may be challenging as some of its typical features (hypertriglyceridaemia, fever, hepatomegaly, heart failure) are often (>95 %) missing and others (arrhythmia, electrocardiographic changes) occur late.

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.

Propofol infusion syndrome in adults: a clinical update

Propofol infusion syndrome is a rare but extremely dangerous complication of propofol administration. Certain risk factors for the development of propofol infusion syndrome are described, such as appropriate propofol doses and durations of administration, carbohydrate depletion, severe illness, and concomitant administration of catecholamines and glucocorticosteroids. The pathophysiology of this condition includes impairment of mitochondrial beta-oxidation of fatty acids, disruption of the electron transport chain, and blockage of beta-adrenoreceptors and cardiac calcium channels. The disease commonly presents as an otherwise unexplained high anion gap metabolic acidosis, rhabdomyolysis, hyperkalemia, acute kidney injury, elevated liver enzymes, and cardiac dysfunction. Management of overt propofol infusion syndrome requires immediate discontinuation of propofol infusion and supportive management, including hemodialysis, hemodynamic support, and extracorporeal membrane oxygenation in refractory cases. However, we must emphasize that given the high mortality of propofol infusion syndrome, the best management is prevention. Clinicians should consider alternative sedative regimes to prolonged propofol infusions and remain within recommended maximal dose limits.

Possible pathogenic mechanism of propofol infusion syndrome involves coenzyme q

BACKGROUND

Propofol is a short-acting intravenous anesthetic agent. In rare conditions, a life-threatening complication known as propofol infusion syndrome can occur. The pathophysiologic mechanism is still unknown. Some studies suggested that propofol acts as uncoupling agent, others suggested that it inhibits complex I or complex IV, or causes increased oxidation of cytochrome c and cytochrome aa3, or inhibits mitochondrial fatty acid metabolism. Although the exact site of interaction is not known, most hypotheses point to the direction of the mitochondria.

METHODS

Eight rats were ventilated and sedated with propofol up to 20 h. Sequential biopsy specimens were taken from liver and skeletal muscle and used for determination of respiratory chain activities and propofol concentration. Activities were also measured in skeletal muscle from a patient who died of propofol infusion syndrome.

RESULTS

In rats, authors detected a decrease in complex II+III activity starting at low tissue concentration of propofol (20 to 25 µM), further declining at higher concentrations. Before starting anesthesia, the complex II+III/citrate synthase activity ratio in liver was 0.46 (0.25) and in skeletal muscle 0.23 (0.05) (mean [SD]). After 20 h of anesthesia, the ratios declined to 0.17 (0.03) and 0.12 (0.02), respectively. When measured individually, the activities of complexes II and III remained normal. Skeletal muscle from one patient taken in the acute phase of propofol infusion syndrome also shows a selective decrease in complex II+III activity (z-score: -2.96).

CONCLUSION

Propofol impedes the electron flow through the respiratory chain and coenzyme Q is the main site of interaction with propofol.

Anesthetic considerations in patients with mitochondrial defects

Mitochondrial disease, once thought to be a rare clinical entity, is now recognized as an important cause of a wide range of neurologic, cardiac, muscle, and endocrine disorders . The incidence of disorders of the respiratory chain alone is estimated to be about 1 per 4-5000 live births, similar to that of more well-known neurologic diseases . High-energy requiring tissues are uniquely dependent on the energy delivered by mitochondria and therefore have the lowest threshold for displaying symptoms of mitochondrial disease. Thus, mitochondrial dysfunction most commonly affects function of the central nervous system, the heart and the muscular system . Mutations in mitochondrial proteins cause striking clinical features in those tissues types, including encephalopathies, seizures, cerebellar ataxias, cardiomyopathies, myopathies, as well as gastrointestinal and hepatic disease. Our knowledge of the contribution of mitochondria in causing disease or influencing aging is expanding rapidly . As diagnosis and treatment improve for children with mitochondrial diseases, it has become increasingly common for them to undergo surgeries for their long-term care. In addition, often a muscle biopsy or other tests needing anesthesia are required for diagnosis. Mitochondrial disease represents probably hundreds of different defects, both genetic and environmental in origin, and is thus difficult to characterize. The specter of possible delayed complications in patients caused by inhibition of metabolism by anesthetics, by remaining in a biochemically stressed state such as fasting/catabolism, or by prolonged exposure to pain is a constant worry to physicians caring for these patients. Here, we review the considerations when caring for a patient with mitochondrial disease.

Lower incidence of emergence agitation in children after propofol anesthesia compared with sevoflurane: a meta-analysis of randomized controlled trials

BACKGROUND

Emergence agitation (EA) from general anesthesia has been reported as an adverse effect of sevoflurane in children. We describe a meta-analysis of randomized controlled trials that compared the incidence of EA between children who underwent sevoflurane anesthesia and those who underwent propofol anesthesia.

METHODS

A literature search was conducted to identify clinical trials that met our inclusion criteria. Prospective randomized trials comparing sevoflurane and propofol anesthesia in children less than 15 years of age were included in the meta-analysis. Data from each trial were combined using the random effects model to calculate pooled odds ratios (ORs) and their corresponding 95 % confidence intervals (CIs). The heterogeneity of data was assessed by Cochran's Q and I (2) tests. Sensitivity analysis was conducted for study quality, patient age, and type of surgical procedure.

RESULTS

The meta-analysis included 14 studies, in which 560 patients received sevoflurane and 548 received propofol. The pooled OR for EA was 0.25 with a 95 % CI of 0.16-0.39 (P = 0.000), which indicates that propofol anesthesia resulted in a lower incidence of EA. The heterogeneity of data was not statistically supported (P = 0.191). All sensitivity analyses strengthened the evidence for the lower incidence of EA with propofol.

CONCLUSIONS

Our meta-analysis demonstrated that EA in children is less likely to occur after propofol anesthesia compared with sevoflurane anesthesia.

Anesthesia with propofol induces insulin resistance systemically in skeletal and cardiac muscles and liver of rats

Hyperglycemia together with hepatic and muscle insulin resistance are common features in critically ill patients, and these changes are associated with enhanced inflammatory response, increased susceptibility to infection, muscle wasting, and worsened prognosis. Tight blood glucose control by intensive insulin treatment may reduce the morbidity and mortality in intensive care units. Although some anesthetics have been shown to cause insulin resistance, it remains unknown how and in which tissues insulin resistance is induced by anesthetics. Moreover, the effects of propofol, a clinically relevant intravenous anesthetic, also used in the intensive care unit for sedation, on insulin sensitivity have not yet been investigated. Euglycemic hyperinsulinemic clamp study was performed in rats anesthetized with propofol and conscious unrestrained rats. To evaluate glucose uptake in tissues and hepatic glucose output [(3)H]glucose and 2-deoxy[(14)C]glucose were infused during the clamp study. Anesthesia with propofol induced a marked whole-body insulin resistance compared with conscious rats, as reflected by significantly decreased glucose infusion rate to maintain euglycemia. Insulin-stimulated tissue glucose uptake was decreased in skeletal muscle and heart, and hepatic glucose output was increased in propofol anesthetized rats. Anesthesia with propofol induces systemic insulin resistance along with decreases in insulin-stimulated glucose uptake in skeletal and heart muscle and attenuation of the insulin-mediated suppression of hepatic glucose output in rats.

Preliminary experience with a combination of dexmedetomidine and propofol infusions for diagnostic cardiac catheterization in children

No specific regimen has been universally accepted as ideal for procedural sedation during cardiac catheterization in infants and children. In this paper, we retrospectively describe our preliminary experience with a continuous infusion of dexmedetomidine and propofol for sedation during cardiac catheterization in children with congenital heart disease. The short-half life of these two drugs creates a potential for easier titration, quicker recovery and less prolonged sedation-related adverse effects. This combination was not only able to limit the dose of either drugs, but was also very stable from cardio-respiratory standpoint. There were no adverse effects noted in our two patients. This initial experience showed that the combination of propofol and dexmedetomidine as a continuous infusion may be a suitable alternative for sedation in spontaneously breathing children undergoing cardiac catheterization.

Drug induced rhabdomyolysis

Rhabdomyolysis is a clinical condition of potential life threatening destruction of skeletal muscle caused by diverse mechanisms including drugs and toxins. Given the fact that structurally not related compounds cause an identical phenotype pinpoints to common targets or pathways, responsible for executing rhabdomyolysis. A drop in myoplasmic ATP paralleled with sustained elevations in cytosolic Ca²⁺ concentration represents a common signature of rhabdomyolysis. Interestingly, cardiac tissue is hardly affected or only secondary, as a consequence of imbalance in electrolytes or acid–base equilibrium.

This dogma is now impaired by compounds, which show up with combined toxicity in heart and skeletal muscle. In this review, cases of rhabdomyolysis with novel recently approved drugs will be explored for new target mechanisms in the light of previously described pathomechanisms.

Use of propofol in pediatric intensive care units: a national survey in Germany

OBJECTIVE

Propofol is not licensed for sedation in pediatric intensive care medicine mainly due to the risk of propofol infusion syndrome. Nevertheless, it is applied by many pediatric intensive care units. The aim of this national survey was to asses the current use of propofol in pediatric intensive care units in Germany.

DESIGN

We performed a nationwide survey. The questionnaire assessed the intensive care unit type, patient numbers, dosing, duration, age and time limits, indications, side effects, and institutional protocols for propofol usage.

SETTING

Pediatric intensive care units in Germany.

SUBJECTS

Questionnaire about routine use of propofol sent to 214 pediatric departments.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred ninety-four questionnaires (90.7%) were returned, ten had to be censored. The final analysis comprised 184 questionnaires (134 pediatric/neonatal intensive care units, 28 pediatric intensive care units, 22 neonatal intensive care units). Seventy-nine percent of intensive care units (n = 145 of 184) used propofol in children under the age of 16 yrs. Of these, 98% were for bolus application (n = 142 of 145), 78% for infusion ≥3 hrs (n = 113 of 145), and 33% for infusion >3 hrs (n = 48 of 145). A lower age limit was applied by 52% (n = 75 of 145) and a dose limit by 51% (n = 74 of 145). The median dose limit was 4 mg/kg/hr; 48% (n = 70 of 145) used 3 mg/kg/hr or less. A time limit was applied by 98% (n = 46 of 47), 70% (n = 33 of 47) used it for ≤24 hrs, and 30% (n = 15 of 47) for >24 hrs. MAIN INDICATIONS FOR PROPOFOL APPLICATION WERE: difficult sedation (44%), postoperative ventilation (43%), and difficult extubation (30%). Seven cases of propofol infusion syndrome were reported by seven centers.

CONCLUSIONS

This study shows that propofol is used off-license by many pediatric intensive care units in Ge. The majority of users has adopted tightly controlled regimens for propofol sedation, and limits the dose to ≤3-4 mg/kg/hr and the maximum application time to 24-48 hrs.

Inborn oxidative phosphorylation defect as risk factor for propofol infusion syndrome

Propofol is an anesthetic agent widely used for induction and maintenance of anesthesia, and sedation in children. Although generally considered as reliable and safe, administration of propofol can occasionally induce a potentially fatal complication known as propofol infusion syndrome (PRIS). Mitochondrial dysfunction has been implicated in the pathogenesis of PRIS. We report on an adult patient with Leber hereditary optic neuropathy (LHON) who developed PRIS. He was a carrier of the m.3460G>A mutation, one of the major three pathogenic point mutations associated with LHON. The propositus was blind and underwent propofol sedation after severe head injury. Five days after start of propofol infusion, the patient died. The activity of complex I of the oxidative phosphorylation (OXPHOS) system was severely deficient in skeletal muscle. Our observation indicates that fulminate PRIS can occur in an adult patient with an inborn OXPHOS defect and corroborates the hypothesis that PRIS is caused by inhibition of the OXPHOS system.

Lactate-to-pyruvate ratio as a marker of propofol infusion syndrome after subarachnoid hemorrhage

BACKGROUND

Propofol infusion syndrome (PRIS) is a rare but frequently fatal condition. It is characterized by cardiovascular collapse and metabolic derangement due to propofol exposure. The pathophysiology of PRIS is poorly understood, and its study has previously been limited to animal models and clinical observations. We present the first in vivo brain biochemical data in a patient with PRIS.

METHODS

We report the case of a 37-year-old woman with PRIS following aneurysmal subarachnoid hemorrhage who was monitored by cerebral microdialysis (CMD). A CMD catheter was inserted into the brain and provided near real-time monitoring of brain energy-related metabolites, including lactate and pyruvate, during the time period surrounding the diagnosis of PRIS. We recorded propofol exposure, clinical manifestations, and relevant laboratory measurements.

RESULTS

CMD revealed a temporal association between propofol exposure and the cerebral lactate-to-pyruvate ratio (LPR). The LPR increased linearly after propofol was restarted following an off period, and the LPR decreased linearly after propofol was discontinued. Serum lactate correlated with clinical worsening after the onset of PRIS, whereas cerebral LPR correlated with propofol exposure.

CONCLUSIONS

Cerebral LPR may be a sensitive marker of PRIS. Increases in LPR following propofol exposure should alert clinicians to the possibility of PRIS and might prompt early discontinuation of propofol thereby avoiding fatal complications.

Analytic Reviews: Propofol Infusion Syndrome in the ICU

Propofol is an alkylphenol derivative named 2, 6, diisopropylphenol and is a potent intravenous short-acting hypnotic agent. It is commonly used as sedation, as well as an anesthetic agent in both pediatric and adult patient populations. There have been numerous case reports describing a constellation of findings including metabolic derangements and organ system failures known collectively as propofol infusion syndrome (PRIS). Although there is a high mortality associated with PRIS, the precise mechanism of action has yet to be determined. The best preventive measure for this syndrome is awareness and avoidance of clinical scenarios associated with development of PRIS. There is no established treatment for PRIS; care is primarily supportive in nature and may include the full array of advanced cardiopulmonary support, including extracorporeal membrane oxygenation (ECMO). This article reviews the reported cases of PRIS and describes the current understanding of the underlying pathophysiology and treatment options.

Propofol infusion syndrome

A review of the history, incidence, presentation, pathophysiology, and treatment of propofol infusion syndrome.

Lactic acidosis: recognition, kinetics, and associated prognosis

Lactic acidosis is a common condition encountered by critical care providers. Elevated lactate and decreased lactate clearance are important for prognostication. Not all lactate in the intensive care unit is due to tissue hypoxia or ischemia and other sources should be evaluated. Lactate, in and of itself, is unlikely to be harmful and is a preferred fuel for many cells. Treatment of lactic acidosis continues to be aimed the underlying source.

A Rare Case of Propofol-Induced Acute Liver Failure and Literature Review

The incidence of drug-induced acute liver failure is increasing. A number of drugs can inhibit mitochondrial functions, alter β-oxidation and cause accumulation of free fatty acids within the hepatocytes. This may result in hepatic steatosis, cell death and liver injury. In our case, propofol, an anesthetic drug commonly used in adults and children, is suspected to have induced disturbance of the mitochondrial respiratory chain, which in consequence led to insufficient energy supply and finally liver failure. We report the case of a 35-year-old Caucasian woman with acute liver failure after anesthesia for stripping of varicose veins. Liver histology, imaging and laboratory data indicate drug-induced acute liver failure, presumably due to propofol. Hepatocyte death and microvesicular fatty degeneration of 90% of the liver parenchyma were observed before treatment with steroids. Six months later, a second biopsy was performed, which revealed only minimal steatosis and minimal periportal hepatitis. We suggest that propofol led to impaired fatty acid oxidation possibly due to a genetic susceptibility. This caused free fatty acid accumulation within hepatocytes, which presented as hepatocellular fatty degeneration and cell death. Large scale hepatocyte death was followed by impaired liver function and, consecutively, progressed to acute liver failure.

Incidence of propofol-related infusion syndrome in critically ill adults: a prospective, multicenter study

Introduction

While propofol is associated with an infusion syndrome (PRIS) that may cause death, the incidence of PRIS is unknown. Determining the incidence of PRIS and the frequency of PRIS-related clinical manifestations are key steps prior to the completion of any controlled studies investigating PRIS. This prospective, multicenter study sought to determine the incidence of PRIS and PRIS-related clinical manifestations in a large cohort of critically ill adults prescribed propofol.

Methods

Critically ill adults from 11 academic medical centers administered an infusion of propofol for [>/=] 24 hours were monitored at baseline and then on a daily basis until propofol was discontinued for the presence of 11 different PRIS-associated clinical manifestations and risk factors derived from 83 published case reports of PRIS.

Results

Among 1017 patients [medical (35%), neurosurgical (25%)], PRIS (defined as metabolic acidosis plus cardiac dysfunction and [>/=] 1 of: rhabdomyolysis, hypertriglyceridemia or renal failure occurring after the start of propofol therapy) developed in 11 (1.1%) patients an average of 3 (1-6) [median (range)] days after the start of propofol. While most (91%) of the patients who developed PRIS were receiving a vasopressor (80% initiated after the start of propofol therapy), few received a propofol dose >83 mcg/kg/min (18%) or died (18%). Compared to the 1006 patients who did not develop PRIS, the APACHE II score (25 +/- 6 vs 20 +/- 7, P = 0.01) was greater in patients with PRIS but both the duration of propofol use (P = 0.43) and ICU length of stay (P = 0.82) were similar.

Conclusions

Despite using a conservative definition for PRIS, and only considering new-onset PRIS clinical manifestations, the incidence of PRIS slightly exceeds 1%. Future controlled studies focusing on evaluating whether propofol manifests the derangements of critical illness more frequently than other sedatives will need to be large. These studies should also investigate the mechanism(s) and risk factors for PRIS.

Update on the propofol infusion syndrome in ICU management of patients with head injury

PURPOSE OF REVIEW

The propofol infusion syndrome is a rare condition characterized by the occurrence of lactic acidosis, rhabdomyolysis and cardiovascular collapse following high-dose propofol infusion over prolonged periods of time. Patients with traumatic brain injury are particularly at risk of developing this complication because large doses of propofol are commonly used to control intracranial pressure, whereas vasopressors are administered to augment cerebral perfusion pressure. In this review, we provide an update on the literature with particular emphasis on patients with traumatic brain injury.

RECENT FINDINGS

Several new case reports and reviews, as well as a number of experiments, have contributed significantly to our increased understanding of the cause of the syndrome. At the basis of the syndrome lies an imbalance between energy utilization and demand resulting in cell dysfunction, and ultimately necrosis of cardiac and peripheral muscle cells. Uncertainty remains whether a genetic susceptibility exists. Nonetheless, the growing number of case reports has made it possible to identify several risk factors.

SUMMARY

Propofol infusion syndrome is a rare but frequently lethal complication of propofol use. In patients with risk factors, such as traumatic brain injury, it is suggested that an infusion rate of 4 mg/kg per hour should not be exceeded. Early warning signs include unexplained lactic acidosis, lipemia and Brugada-like ECG changes. When these occur, propofol infusion should be discontinued immediately.

Vasopressors and propofol infusion syndrome in severe head trauma

INTRODUCTION

Propofol infusion syndrome (PRIS) is a rare, but lethal complication of high-dose propofol infusions. We undertook this study to evaluate the incidence of PRIS in a cohort of patients with severe head trauma and its relation to the use of vasopressors.

METHODS

We reviewed all patients with severe head trauma admitted to our Neuro-Intensive Care Unit over a 4-year period for use of propofol and vasopressors. Those patients who developed unexplained acidosis, creatine kinase elevation unrelated to trauma, and electrocardiographic changes were considered having PRIS. We investigated the concomitant use of vasopressors while propofol was used and calculated odds ratios for developing PRIS.

RESULTS

We report three adult patients who developed PRIS out of 50 (6%) admitted patients with severe head trauma on propofol infusions. Two of these patients survived and one expired after withdrawal of life support. Concomitant use of vasopressors was associated with development of PRIS in this cohort (odds ratio 29, 95% CI 1.5-581, P < 0.05).

CONCLUSIONS

Awareness and early recognition of PRIS in critically ill neurosurgical patients on vasopressors and daily screening for creatine kinase elevation, unexplained acidosis, or electrocardiographic changes may reduce the incidence and case-fatality.

Effects of dexmedetomidine on propofol and remifentanil infusion rates during total intravenous anesthesia for spine surgery in adolescents

INTRODUCTION

Total intravenous anesthesia with propofol and a synthetic opioid is a frequently chosen anesthetic technique for posterior spinal fusion. Despite its utility, adverse effects may occur with high or prolonged propofol dosing regimens including delayed awakening. The current study investigated the propofol-sparing effects of the concomitant administration of the alpha(2)-adrenergic agonist, dexmedetomidine, during spinal fusion surgery in adolescents.

METHODS

The surgical database of the department of orthopedic surgery was searched and patients (12-21 years of age) were identified who had undergone spinal fusion for either idiopathic or neuromuscular scoliosis during the past 24 months. Patients were assigned to two groups. Group 1 included patients anesthetized with propofol and remifentanil and group 2 included patients anesthetized with dexmedetomidine, propofol, and remifentanil. In the latter group, dexmedetomidine was administered as a continuous infusion of 0.5 microg.kg(-1).h(-1) started after the induction of anesthesia without a loading dose. Propofol was adjusted to maintain the bispectral index (BIS) number at 40-50 and remifentanil was adjusted to maintain the mean arterial pressure (MAP) at 50-65 mmHg. Labetolol or hydralazine was used if the MAP could not be maintained at 50-65 mmHg with remifentanil up to a maximum dose of 0.6 microg/kg/min. Statistical analysis included a nonpaired t-test for parametric data (age, weight, remifentanil/propofol infusion requirements, and heart rate/blood pressure values). A nonparametric statistical analysis (Dunn) was used to compare BIS numbers. Parametric data are presented as the mean +/- SD while nonparametric data are presented as the median and the 95th percentile confidence intervals.

RESULTS

Twelve patients received propofol-remifentanil-dexmedetomidine and 24 received propofol-remifentanil. There were no differences in the demographic data, BIS numbers or hemodynamic parameters between the two groups. There was a reduction in the propofol infusion requirements in patients who also received dexmedetomidine (71 +/- 11 microg.kg(-1).min(-1)) compared with those receiving only propofol-remifentanil (101 +/- 33 microg.kg(-1).min(-1), P = 0.0045). No difference was noted in the remifentanil infusion requirements or the use of supplemental agents (hydralazine and labetolol) to maintain controlled hypotension.

CONCLUSION

The concomitant use of dexmedetomidine in patients undergoing spinal fusion reduces propofol infusion requirements when compared with those patients receiving only propofol and remifentanil.

Propofol infusion syndrome: an overview of a perplexing disease

Propofol (2, 6-diisopropylphenol) is a potent intravenous hypnotic agent that is widely used in adults and children for sedation and the induction and maintenance of anaesthesia. Propofol has gained popularity for its rapid onset and rapid recovery even after prolonged use, and for the neuroprotection conferred. However, a review of the literature reveals multiple instances in which prolonged propofol administration (>48 hours) at high doses (>4 mg/kg/h) may cause a rare, but frequently fatal complication known as propofol infusion syndrome (PRIS). PRIS is characterized by metabolic acidosis, rhabdomyolysis of both skeletal and cardiac muscle, arrhythmias (bradycardia, atrial fibrillation, ventricular and supraventricular tachycardia, bundle branch block and asystole), myocardial failure, renal failure, hepatomegaly and death. PRIS has been described as an 'all or none' syndrome with sudden onset and probable death. The literature does not provide evidence of degrees of symptoms, nor of mildness or severity of signs in the clinical course of the syndrome. Recently, a fatal case of PRIS at a low infusion rate (1.9-2.6 mg/kg/h) has been reported. Common laboratory and instrumental findings in PRIS are myoglobinuria, downsloping ST-segment elevation, an increase in plasma creatine kinase, troponin I, potassium, creatinine, azotaemia, malonylcarnitine and C5-acylcarnitine, whereas in the mitochondrial respiratory electron transport chain, the activity of complex IV and cytochrome oxidase ratio is reduced. Propofol should be used with caution for sedation in critically ill children and adults, as well as for long-term anesthesia in otherwise healthy patients, and doses exceeding 4-5 mg/kg/h for long periods (>48 h) should be avoided. If PRIS is suspected, propofol must be stopped immediately and cardiocirculatory stabilization and correction of metabolic acidosis initiated. So, PRIS must be kept in mind as a rare, but highly lethal, complication of propofol use, not necessarily confined to its prolonged use. Furthermore, the safe dosage of propofol may need re-evaluation, and new studies are needed.

[Effects of sedative agents on metabolic demand]

Literature about the effects of sedative drugs on the metabolic demand of critically ill patients is relatively old and of relatively poor quality. Most are experimental or observational studies. Level of evidence is therefore relatively low corresponding to "expert opinion". The effects of analgesics and hypnotics on tissue metabolic demand associated remain difficult to be adequately quantified. They are essentially related to a decreased neuro-humoral response to stress. This response involves principally the sympathetic system, which could be effectively blocked by most of the anesthetic agents. Other factors could participate to the observed reduction in tissue metabolic demand, as a decrease in spontaneous muscular activity, a reduction in work of breathing and/or a decrease in body temperature. The relative contribution of these different factors will depend on the clinical situation of the patient. Proper effects of anesthetic agents on cellular metabolism are limited as they can only decrease the functional component of this metabolism especially at the level of the heart and to some extent, at the level of the brain. Although the control of the sympathetic activity may be beneficial in critically ill patient, complete sympathetic blockade could be detrimental. Indeed, when oxygen transport to the tissues is acutely reduced, the sympathetic system plays an important role in the redistribution of blood flow according of local metabolic demand. The complete blunting of the neuro-humoral response to stress and therefore of the sympathetic system alters this physiological mechanism and results in a decrease in tissue oxygen extraction capabilities. An imbalance between tissue oxygen demand and delivery could appear with the development of cellular hypoxia. The institution of sedation in a critically ill patient requires careful evaluation of the sedation level using an appropriate scale. In patients in whom a reduction in metabolic demand is specifically requested, but also in patients with limited oxygen transport, the effects of sedative agents on the oxygen consumption-oxygen delivery relationship must also be monitored. The choice of the different agents to be administered will depend on the predefined objectives. As far as intravenous agents are concerned, there is no evidence than one association is more efficient in reducing patient's metabolic demand.

Medication-related complications in the trauma patient

Trauma patients are twice as likely to have adverse reactions to medication as nontrauma patients. The need for medication in trauma patients is high. Surgery is often necessary, and immunosuppression and hypercoagulability may be present. Adverse drug events can be caused in part by altered pharmacokinetics, drug interactions, and polypharmacy. Medications may also have serious long-term adverse effects, which must be considered. It is not the purpose of this review article to discuss all adverse effects of all medications. This article will discuss the more common adverse effects of medications for trauma patients in the acute care setting, in the following categories: pain control, sedation, antibiotics, seizure prophylaxis in head trauma, atrial fibrillation, deep vein thrombosis and pulmonary embolism prophylaxis, hemodynamic support, adrenal insufficiency, factor VIIa.

Propofol-related infusion syndrome in intensive care patients

The Institute of Medicine has identified adverse drug events as factors that significantly contribute to increased patient morbidity and mortality. As critically ill patients receive numerous drugs to treat a multitude of complicated health problems, they are at high risk for adverse drug events. Sedation is often a key requirement for the optimal management of critical illness, and propofol, a common sedative, has many desirable characteristics that make it the ideal agent in numerous circumstances. However, over the last decade, increasing numbers of reports have described a potentially fatal adverse effect called propofol-related infusion syndrome. Whether this adverse drug event is preventable is unclear, but recommendations have been proposed to minimize the potential for development of this syndrome. Research is under way to collect data on the use of propofol in intensive care units and on its prevalence.

Propofol infusion syndrome in anaesthesia and intensive care medicine

PURPOSE OF REVIEW

Propofol infusion syndrome is a rare but often fatal syndrome, characterized by lactacidosis, lipaemic plasma and cardiac failure, associated with propofol infusion over prolonged periods of time. As propofol is used worldwide, knowledge of propofol infusion syndrome is essential for all anaesthesiologists and intensive care physicians. This review will provide an update on reported cases, and describe recent findings relevant to the pathophysiology and clinical presentation of propofol infusion syndrome.

RECENT FINDINGS

Case reports of propofol infusion syndrome have contributed new pathophysiological evidence. Reported cases of similar syndromes may represent initial propofol infusion syndrome, and may help to identify further risk factors such as low carbohydrate supply and early warning signs such as lactacidosis. Newly identified gene defects mimicking propofol infusion syndrome may elicit the underlying genetic susceptibility. Recommendations for the limitation of propofol use have been devised by various institutions.

SUMMARY

Propofol infusion syndrome must be kept in mind as a rare but highly lethal complication of propofol use, not necessarily confined to the prolonged use of propofol. Dose limitations must be adhered to, and early warning signs such as lactacidosis should lead to the immediate cessation of propofol infusion.

New Anticonvulsants—New Adverse Effects

Ongoing refinements in pharmacology continue to provide new medications for the treatment of seizure disorders and other neurologic conditions. The authors present the cases of two children who developed relatively uncommon adverse effects to new anticonvulsant medications, including metabolic acidosis with topiramate and hyponatremia with oxcarbazepine. In one of our two patients, intraoperative acidosis related to topiramate was noted. Appropriate investigation with documentation of normal serum lactate resulted in the exclusion of other potentially serious causes of acidosis and in the identification of topiramate as the causative agent. In our second patient, hyponatremia and status epilepticus resulted from therapy with oxcarbazepine. Prompt recognition of hyponatremia, fluid restriction, and cessation of oxcarbazepine therapy resulted in prompt correction of the hyponatremia. We review previous reports of these adverse effects with topiramate and oxcarbazepine, describe the pathophysiology of these metabolic alterations, provide treatment strategies, and make suggestions for monitoring patients during therapy with these anticonvulsant medications.

Paediatric anaesthesia and inhalation agents

Inhalation agents are amongst the mainstays of paediatric anaesthesia, as children are often induced by mask before venous access is obtained. Children do not like needles and obtaining venous access in an awake and moving child can be very demanding. Safety aspects are of particular importance in paediatric anaesthesia. Therefore, the possibility of monitoring end-tidal concentrations facilitates correct dosing in all patients, from the preterm infant weighing less than 1000 g to the adult-sized adolescent. For induction, sevoflurane has nearly universally replaced halothane, leading to increased cardiovascular safety. The main disadvantages of inhalation agents, especially sevoflurane and desflurane, are delirious behaviour and agitated states during emergence. In addition, there remains uncertainty regarding the relevance of the cerebral stimulating pattern of some of these agents. Inhalation anaesthesia has a long tradition, whereas the experience with propofol is comparatively small. The incidence and clinical relevance of the propofol infusion syndrome during clinical anaesthesia are still unknown. Inhalation anaesthesia is still considered to be the gold standard by the overwhelming majority of paediatric anaesthetists world-wide, however, intravenous techniques can be an attractive alternative in specific clinical situations.

Adverse Events Associated with Sedatives, Analgesics, and Other Drugs That Provide Patient Comfort in the Intensive Care Unit

Since the 2002 publication of multidisciplinary clinical practice guidelines for intensive care unit (ICU) sedation and analgesia, additional information regarding adverse drug events has been reported. Our understanding of the risks associated with these sedative and analgesic agents promises to improve outcomes by helping clinicians identify and respond to therapeutic misadventures sooner. This review focuses on many issues, including the potentially fatal consequences associated with the propofol infusion syndrome, the evolving understanding of propylene glycol intoxication associated with parenteral lorazepam, new data involving high-dose and long-term dexmedetomidine therapy, haloperidol- and methadone-related prolongation of QTc intervals on the electrocardiogram, adverse events associated with atypical antipsychotics, and the potential for nonsteroidal antiinflammatory drugs to interfere with bone healing.

Propofol-Infusionssyndrom

Propofol infusion syndrome has not only been observed in patients undergoing long-term sedation with propofol, but also during propofol anesthesia lasting 5 h. It has been assumed that the pathophysiologic cause is propofol's impairment of oxidation of fatty acid chains and inhibition of oxidative phosphorylation in the mitochondria, leading to lactate acidosis and muscular necrosis. It has been postulated that propofol might act as a trigger substrate in the presence of priming factors. Severe diseases in which the patient has been exposed to high catecholamine and cortisol levels have been identified as trigger substrates. Once the development of propofol infusion syndrome is suspected, propofol infusion has to be stopped immediately and specific therapeutic measures initiated, including cardiocirculatory stabilization and correction of metabolic acidosis. To increase elimination of propofol and its potential toxic metabolites, hemodialysis or hemofiltration are recommended. Due to its possible fatal side effects, the use of propofol for long-term sedation in critically ill patients should be reconsidered. In cases of unexplained lactate acidosis occurring during continuous propofol infusion, propofol infusion syndrome must be taken into consideration.