The 'propofol infusion syndrome': the facts, their interpretation and implications for patient care

Unusual case of propofol-related infusion syndrome complicating severe COVID-19 ARDS

An elderly man presenting with shortness of breath and hypoxaemia was admitted with acute hypoxic respiratory failure secondary to COVID-19 pneumonia. Due to worsening hypoxaemia, he was transferred to the intensive care unit and required mechanical ventilation. Propofol was infused at 1.5-4 mg/kg/hour. Within 48 hours of initiation, we noticed worsening metabolic acidosis, acute kidney injury, hyperkalaemia, hyperphosphataemia, hypertriglyceridaemia, elevated creatine kinase and elevated myoglobin levels. Suspecting propofol-related infusion syndrome (PRIS), we discontinued his propofol infusion immediately and initiated supportive measures. In 48 hours, there was a significant improvement in metabolic acidosis, hypertriglyceridaemia, rhabdomyolysis and renal function. The propofol infusion rate and cumulative propofol dosage (under 140 mg/kg) were well below levels associated with PRIS. COVID-19's pathogenesis, still under investigation, may have contributed to this presentation. It is imperative for clinicians to maintain a high degree of suspicion once propofol is initiated, regardless of the cumulative dose or rate of infusion.

Effect of noradrenaline on propofol-induced mitochondrial dysfunction in human skeletal muscle cells

Background

Mitochondrial dysfunction is a hallmark of both critical illness and propofol infusion syndrome and its severity seems to be proportional to the doses of noradrenaline, which patients are receiving. We comprehensively studied the effects of noradrenaline on cellular bioenergetics and mitochondrial biology in human skeletal muscle cells with and without propofol-induced mitochondrial dysfunction.

Methods

Human skeletal muscle cells were isolated from vastus lateralis biopsies from patients undergoing elective hip replacement surgery (n = 14) or healthy volunteers (n = 4). After long-term (96 h) exposure to propofol (10 µg/mL), noradrenaline (100 µM), or both, energy metabolism was assessed by extracellular flux analysis and substrate oxidation assays using [14C] palmitic and [14C(U)] lactic acid. Mitochondrial membrane potential, morphology and reactive oxygen species production were analysed by confocal laser scanning microscopy. Mitochondrial mass was assessed both spectrophotometrically and by confocal laser scanning microscopy.

Results

Propofol moderately reduced mitochondrial mass and induced bioenergetic dysfunction, such as a reduction of maximum electron transfer chain capacity, ATP synthesis and profound inhibition of exogenous fatty acid oxidation. Noradrenaline exposure increased mitochondrial network size and turnover in both propofol treated and untreated cells as apparent from increased co-localization with lysosomes. After adjustment to mitochondrial mass, noradrenaline did not affect mitochondrial functional parameters in naïve cells, but it significantly reduced the degree of mitochondrial dysfunction induced by propofol co-exposure. The fatty acid oxidation capacity was restored almost completely by noradrenaline co-exposure, most likely due to restoration of the capacity to transfer long-chain fatty acid to mitochondria. Both propofol and noradrenaline reduced mitochondrial membrane potential and increased reactive oxygen species production, but their effects were not additive.

Conclusions

Noradrenaline prevents rather than aggravates propofol-induced impairment of mitochondrial functions in human skeletal muscle cells. Its effects on bioenergetic dysfunctions of other origins, such as sepsis, remain to be demonstrated.

SAFETY OF PROPOFOL ANESTHESIA DURING NEUROSURGICAL OPERATIONS

OBJECTIVE

The aim: The purpose of this study was to assess the safety of propofol use during neurosurgical operations of different durations.

PATIENTS AND METHODS

Materials and methods: 72 patients were divided into three groups depending on the type of operations; it were group 1 (ventriculostomy), group 2 (hematoma removal), and group 3 (tumor removal), the anesthesia durations in these groups were 65±5 min, 145±7 min and 225±10 min, respectively. Total propofol doses in patients of groups 1, 2, and 3 were 452±22 mg, 710±42 mg, and 966±51 mg, respectively. Before intervention and 1 h post operation, blood gas composition, serum levels of transaminase, triglycerides, creatine phosphokinase, and potassium, rate of urine output, level of mean arterial pressure, and heart rhythm rate were determined.

RESULTS

Results: No significant deviations concerning hemodynamic indicators, blood gas composition, changes of creatine kinase activity were found for any group patients during the perioperative period. The rate of urine output in all patients reached above 0.5 ml/kg/h without saluretics use. The deviated transaminase values returned to their normal ones during 24 h post intervention. The triglycerides levels were in normal range proving the absence of propofol doses used on the lipid metabolism.

CONCLUSION

Conclusions: Anesthetic protection of neurosurgical interventions using propofol in doses 2.5-3 mg/kg and 3.60.3 mg/kg/h for induction anesthesia and for anesthesia support, respectively, is safe and does not lead to dangerous undesired consequences. However, the propofol use for prolonged patient sedation and his/her adaptation for prolonged lung ventilation needs further studies.

The incidence of propofol infusion syndrome in critically-ill patients

PURPOSE

PRIS is a potentially fatal syndrome characterized by various clinical symptoms and abnormalities. Experts suggest that propofol treatment duration ≥48 h or dose ≥83 μg/kg/min is associated with developing PRIS. We hypothesized PRIS might be underdiagnosed due to the overlap of PRIS clinical manifestations with critical illnesses.

MATERIALS AND METHODS

Multihospital, retrospective study of adult patients who received continuous propofol infusion ≥48 h or dose ≥60μg/kg/min for >24 h since admission were assessed for the development of PRIS.

RESULTS

The incidence of PRIS was 2.9% with a PRIS-associated mortality rate of 36.8%. In PRIS patients, propofol was administered at a median dose of 36.4 μg/kg/min and over a median duration of 147.0 h. The development of PRIS was observed at a median of 125.0 h post-propofol initiation and a cumulative dose of 276.5 mg/kg. The development of metabolic acidosis (78.9%), cardiac dysfunction (52.6%), hypertriglyceridemia (100%), and rhabdomyolysis (26.3%) were observed in our PRIS patients.

CONCLUSION

PRIS can often be overlooked and underdiagnosed. It is important to monitor for early signs of PRIS in patients who are on prolonged propofol infusion. Prompt recognition and interventions can minimize the dangers resulting from PRIS.

Propofol-Related Infusion Syndrome: A Clinical Review

Propofol-related infusion syndrome (PRIS) is a lethal condition characterized by multiple organ system failures. It can occur due to prolonged administration of propofol (an anesthetic) in mechanically intubated patients. The main presenting features of this condition include cardiovascular dysfunction with particular emphasis on impairment of cardiovascular contractility, metabolic acidosis, lactic acidosis, rhabdomyolysis, hyperkalaemia, lipidaemia, hepatomegaly, acute renal failure, and eventually mortality in most cases. The significant risk factors that predispose one to PRIS are: critical illnesses, increased serum catecholamines, steroid therapy, obesity, young age (significantly below three years), depleted carbohydrate stores in the body, increased serum lipids, and most importantly, heavy or extended dosage of propofol. The primary pathophysiology behind PRIS is the disruption of the mitochondrial respiratory chain that causes inhibition of adenosine triphosphate (ATP) synthesis and cellular hypoxia. Further, excess lipolysis of adipose tissue occurs, especially in critically ill patients where the energy source is lipid breakdown instead of carbohydrates. This process generates excess free fatty acids (FFAs) that cannot undergo adequate beta-oxidation. These FFAs contribute to the clinical pathology of PRIS. It requires prompt management as it is a fatal condition. The clinicians must observe the patient's electrocardiogram (ECG), serum creatine kinase, lipase, amylase, lactate, liver enzymes, and myoglobin levels in urine, under propofol sedation. Doctors should immediately stop propofol infusion upon noticing any abnormality in these parameters. The other essentials of management of various manifestations of PRIS will be discussed in this article, along with a detailed explanation of the condition, its risk factors, diagnosis, pathophysiology, and presenting features. This article aims to make clinicians more aware of the occurrence of this syndrome so that better ways to manage and treat this condition can be formulated in the future.

Propofol Infusion Syndrome in the Postoperative Period of a Kidney Transplant

Sedation during medical procedures poses a risk to any patient, and the use of specific anesthetic agents should be carefully considered to avoid adverse outcomes. We report on a patient with propofol infusion syndrome diagnosed during the post-operative period of a renal transplant. A 58-year-old female on chronic hemodialysis due to end stage kidney disease secondary to microscopic polyangiitis underwent kidney transplant from a deceased donor. Anesthetic induction was performed with fentanyl, propofol, and cisatracurium, and maintained with continuous propofol infusion. In the recovery room, the patient developed somnolence, tachypnea, and thoracoabdominal dissociation secondary to residual neuromuscular block. An arterial-blood gas test indicated acidemia, high pCO₂, low HCO₃, and mildly increased serum lactate. The patient remained hemodynamically stable, on volume-controlled ventilation, with sedation by continuous propofol infusion. Blood gas tests revealed persistent acidemia without tissue hypoperfusion. Doppler ultrasound of the renal graft reported adequate blood flow and serum triglycerides were elevated. A diagnosis of propofol infusion syndrome was made, and infusion ceased. A decrease in serum lactate levels was observed, with normalization 4 h later. This case highlights the importance of considering adverse effects of anesthetic agents as the cause of post-operative complications when prolonged sedation is required.

Propofol infusion syndrome: a structured literature review and analysis of published case reports

Propofol infusion syndrome is a rare, potentially fatal condition first described in children in the 1990s and later reported in adults. We provide a narrative review of what is currently known about propofol infusion syndrome, including a structured analysis of all published case reports; child and adult cases were analysed separately as propofol is no longer used for long-term sedation in children. The review contains an update on current knowledge of the pathophysiology of this condition along with recommendations for its diagnosis, prevention, and management. We reviewed 108 publications documenting 168 cases of propofol infusion syndrome. We evaluated clinical features and analysed factors influencing mortality in child and adult cases using separate multivariate analysis models. We used separate multiple linear regression models to analyse relationships between cumulative dose of propofol and the number of features seen and organ systems involved. Lipidaemia, fever, and hepatomegaly occurred more frequently in children than in adults, whilst rhabdomyolysis and hyperkalaemia were more frequent in adults. Mortality from propofol infusion syndrome is independently associated with fever and hepatomegaly in children, and electrocardiogram changes, hypotension, hyperkalaemia, traumatic brain injury, and a mean propofol infusion rate >5 mg kg^-1 h^-1 in adults. The cumulative dose of propofol was associated with an increased number of clinical features and the number of organ systems involved in adult cases only. Clinicians should consider propofol infusion syndrome in cases of unexplained metabolic acidosis, ECG changes, and rhabdomyolysis. We recommend early consideration of continuous haemofiltration in the management of propofol infusion syndrome.

Clinical analysis of hyperkalemia after esophagectomy: A case report

RATIONALE

The occurrence of hyperkalemia after esophagectomy is clinically rare. Patients who underwent esophagectomy often have a serum potassium level due to perioperative reduced intake, fluids loss, consumption and other reasons. These patients often require the artificial administration of potassium. Rapid fluid loss and physiological consumption lead to the deficiency of potassium, even hypokalemia. Patients often require the addition of a large amount of potassium after operation. The occurrence of hyperkalemia after esophagectomy is never been reported.

PATIENT CONCERNS

The patient presented with continuous tachycardia, palpitations, chest tightness, progressive nausea, irritability, progressive myasthenia gravis.

DIAGNOSES

Hyperkalemia, sepsis, acidosis, diabetes, postoperative esophageal cancer.

INTERVENTIONS

Prompt anti-infection treatment and the management of blood sugar, hemodialysis was performed to correct sthe acidosis and electrolyte disorder OUTCOMES:: All symptoms were alleviated.

LESSONS

Therefore, there is a need to regularly test electrolytes, especially in patients with diabetes, as well as better blood glucose control. Attention should be paid to the potential of infection, and to avoiding ketoacidosis and risk of sepsis.

In vivo study of hepatic oxidative stress and mitochondrial function in rabbits with severe hypotension after propofol prolonged infusion

In humans, prolonged sedations with propofol or using high doses have been associated with propofol infusion syndrome. The main objective of this study was to evaluate the effects of prolonged high-dose administration of a specific propofol emulsion (Propofol Lipuro) and an improved lipid formulation (SMOFlipid) in liver mitochondrial bioenergetics and oxidative stress of rabbits, comparatively to a saline control. Twenty-one male New Zealand white rabbits were randomly allocated in three groups that were continuously treated for 20 h. Each group of seven animals received separately: NaCl 0.9 % (saline), SMOFlipid (lipid-based emulsion without propofol) and Lipuro 2 % (propofol lipid emulsion). An intravenous propofol bolus of 20 mg kg⁻¹ was given to the propofol Lipuro group to allow blind orotracheal intubation and mechanical ventilation. Anesthesia was maintained using infusion rates of: 20, 30, 40, 50 and 60 mg kg⁻¹ h⁻¹, according to the clinical scale of anesthetic depth and the index of consciousness values. The SMOFlipid and saline groups received the same infusion rate as the propofol Lipuro group, which were infused during 20 consecutive hours. At the end, the animals were euthanized, livers collected and mitochondria isolated by standard differential centrifugation. Mitochondrial respiration, membrane potential, swelling and oxidative stress were evaluated. Data were processed using one-way ANOVA (p < 0.05). The animals revealed a significant decrease in cardiovascular parameters showing bradycardia and severe hypotension. No statistical differences were observed when using pyruvate as substrate, however, when using succinate as respiratory substrate, significant decrease in ADP-stimulated respiration rate was observed for SMOFlipid group (p = 0.002). Lipid peroxides (p < 0.01) and protein carbonyls (p = 0.01) showed a statistically significant difference between propofol Lipuro and the SMOFlipid groups. These results suggest that lipid-based emulsions can be involved in the regulation of different pathways that ultimately lead to a decrease of state 3 mitochondrial respiration rate. The infusion of propofol Lipuro during prolonged periods, in addition to marked hypotension and hypoperfusion, also showed to have higher anti-oxidant activity and lower impairment of the mitochondrial function comparatively to the improved lipid formulation, SMOFlipid, using the rabbit as animal model.

Propofol Use in Israeli PICUs

OBJECTIVES

In Israel, the recommendation for the use of propofol is age limited. Furthermore, procedural sedations involving propofol must be performed only by anesthesiologists. Propofol is frequently used in the PICUs in Israel.

DESIGN

Questionnaire survey.

SETTING

PICUs in Israel.

SUBJECTS

None.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Physicians from 13 PICUs (86.6%) responded to the questionnaire. Propofol was used for induction, procedural sedation, and ongoing ICU sedation in 100%, 70%, and 12% of cases, respectively. Eighty-eight percent of the participants limited the duration of propofol infusion to 24 hours at a dose of less than or equal to 4 mg/kg/1 hr, but 40% administered propofol as needed without specifying an upper dose limit. Twenty-five percent encountered adverse effects such as apnea, desaturation, and bradycardia, but only two of the participants suspected propofol infusion syndrome, each in one patient. All the participants agreed to expand the indications for propofol use in the pediatric age group. Ketamine was the drug mostly used instead of propofol (50%), followed by fentanyl (30%), midazolam (30%), and remifentanil (5%). Apart from anesthesiologists, PICU physicians support the use of propofol by physicians who have the technical skills for rapid-sequence intubation and advanced airway management.

CONCLUSIONS

Off-label use of propofol is an accepted practice in Israeli PICUs. Propofol has a unique profile that makes it an attractive sedative agent in many clinical settings. PICU physicians may want to prescribe it, at least for short periods and at low doses.

Propofol-related infusion syndrome: rare and fatal

Propofol is one of the most commonly used sedating agents in critical care units worldwide. It is generally well tolerated and preferred for its pharmacokinetic profile. Here, we describe a rare and devastating adverse effect of propofol, the propofol-related infusion syndrome.

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 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.

Procedural sedation and analgesia in pediatric patients

A spectrum of conditions requires sedation and analgesia in pediatric population. Ineffective treatment of pain may result in physiological and behavioral responses that can adversely affect the developing nociceptive system. The recognition of pain in children can be facilitated by different pain scales. This article reviews the procedural sedation and analgesia (PSA) practices in children along with pharmacology of the drugs used for this purpose.

Use of propofol for short duration procedures in children with long chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) or trifunctional protein (TFP) deficiencies

The medication propofol, commonly used for anesthesia, has been avoided in patients with mitochondrial fatty acid oxidation disorders (FAODs) due to concerns that it contains long-chain fatty acids (LCFAs), and because of reports of severe side effects in some critically ill patients receiving high-dose propofol infusions that mimic some of the symptoms regularly found in FAOD patients. In this secondary analysis, we examined the outcomes of 8 children with long-chain 3-hydroxyacyl CoA dehydrogenase (LCHAD) deficiency or trifunctional protein (TFP) deficiency who were repeatedly sedated for an electroretinogram (ERG) as part of a longitudinal study of the progression of chorioretinopathy commonly found in this population. A total of 39 sedated ERG procedures were completed using propofol for sedation. The propofol dosing, estimated total energy needs of the subject, and inpatient dietary intake recording were completed in 32 of these procedures. The LCFAs in the propofol provided approximately 1.0% of the average total daily energy needs. The sedation with propofol resulted in no adverse side effects and was safely used in this short duration procedure.

Is propofol a friend or a foe of the pediatric intensivist? Description of propofol use in a PICU*

OBJECTIVE

The primary objective is to describe the practice patterns of nonprocedural propofol use in a single-center referral PICU. The secondary objective is to describe the rate of concordance of propofol use with the PICU local practice of a maximum mean rate of 4 mg/kg/hr and a maximum duration of 24 hours and to assess for signs and symptoms of propofol infusion syndrome.

DESIGN

Retrospective descriptive cohort study.

SETTING

PICU of a tertiary care teaching hospital and referral hospital for the Western Canada.

PATIENTS

Children 1 month to 17 years old who received a nonprocedural propofol infusion between January 1, 2009, and December 31, 2009.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Two hundred twenty-three infusions (representing 210 unique patients) were included in the study. The median average infusion rate (interquartile range) including boluses was 2.7 mg/kg/hr (1.9-3.6 mg/kg/hr), and the mean infusion duration (SD) was 10.3 hours (6.7 hr). Eighty-seven percent and 98% of infusions were concordant with PICU intensivists self-reported practice maximum rate and duration, respectively. No cases of propofol-related infusion syndrome or deaths associated with propofol infusions were identified.

CONCLUSIONS

The use of propofol infusions was in concordance with PICU local practice, and propofol infusion syndrome did not developed in patients. In agreement with previous recommendations, propofol infusions in the PICU appear to be safe when limiting doses to 4 mg/kg/hr and for less than 24 hours; however, appropriate monitoring of adverse effects is still warranted due to absence of robust evidence.

Propofol infusion syndrome associated with large-dose infusion for treatment of seizure activity

This article presents a case study of a young man with a history of epilepsy and the use of a propofol infusion to control his symptoms. Propofol-related infusion syndrome is presented.

Propofol infusion syndrome: a lethal condition in critically injured patients eliminated by a simple screening protocol

Propofol infusion syndrome (PIS) is defined by arrhythmia, rhabdomyolysis, lactic acidosis, and unrecognized leads to death. We sought to determine the incidence of PIS in trauma patients and evaluate the efficacy of a prospective screening protocol in this patient population.

MATERIALS AND METHODS

In Phase I of the before-and-after study (1st January, 2005-31st December, 2005), trauma patients who received propofol were evaluated. Records were reviewed for demographics, injury severity, propofol time, dose, and rates, laboratory values, and adverse events. Patients were identified with PIS based on two of the following criteria: (1) cardiac arrhythmia/collapse, (2) metabolic acidosis, (3) rhabdomyolysis, and (4) acute kidney injury. Phase II (1st January, 2006-31st December, 2011) consisted of a prospective screening protocol (elevated lactate or creatine phosphokinase (CPK)) to identify patients at risk for PIS.

RESULTS

207 patients were identified in Phase I. 6 (2.9%) developed PIS with a 50% mortality. No differences were seen in age, gender, or mechanism. PIS patients were more injured (median ISS 44 vs 26, p=0.04; median head AIS 5 vs 4, p=0.003) and received more propofol (median 50,350 vs 9770 mg, p=0.001) with longer infusion times (413 vs 65 h, p=0.001). Sodium, creatinine, and CPK levels were higher in those that developed PIS (160 vs 145 mmol/L, p=0.001; 4.3 vs 1.1mg/dL, p=0.005; 59,871 vs 520 U/L; p=0.002). Pre-screening PIS incidence was 2.9% (6/207), but after screening (January 2006) the incidence dropped to 0.19% (2/1038, p<0.001).

CONCLUSIONS

PIS is a morbid and lethal entity associated with sedation of critically injured patients. A simple screening procedure utilizing serum CPK (<5000 U/L) can essentially eliminate the development of PIS.

Propofol-related infusion syndrome: role of propofol in medical complications of sedated critical care patients

BACKGROUND

Propofol is a popular anesthetic and sedative. Use of propofol has increased manifold in this country over the last decade, and it is most commonly used in intensive care settings. Its rapid action with short half-life, decreased cerebral oxygen consumption, and reduction of intracranial pressure are properties that have made it a favorite in the intensive care unit. Many of these patients are critically ill or injured and require prolonged sedation. Propofol has been associated with morbidity and mortality, and in such cases the question often arises regarding the role propofol plays in these complications.

OBJECTIVE

To address the issue of propofol-related infusion syndrome and its management.

METHOD

A hypothetical clinical vignette was created to give a classic presentation of propofol-related infusion syndrome.

CONCLUSION

It is hoped that this short report will bring more awareness of this entity so that it will be considered in the differential diagnosis in sedated critical care patients.

Propofol infusion syndrome in refractory status epilepticus

BACKGROUND AND PURPOSE

Propofol is used for treating refractory status epilepticus, which has high rate of mortality. Propofol infusion syndrome is a rare but often fatal syndrome, characterized by lactic acidosis, lipidemia, and cardiac failure, associated with propofol infusion over prolonged periods of time. We investigated the clinical factors that characterize propofol infusion syndrome to know the risk of them in refractory status epilepticus.

METHODS

This retrospective observation study was conducted in Samsung medical center from Jan. 2005 to Dec. 2009. Thirty two patients (19 males, 13 females, aged between 16 and 64 years), with refractory status epilepsy were included. Their clinical findings and treatment outcomes were evaluated retrospectively. We divided our patients into established status epilepticus (ESE) and refractory status epilepticus (RSE). And then the patients with RSE was further subdivided into propofol treatment group (RSE-P) and the other anesthetics treatment group (RSE-O). We analyzed the clinical characteristics by comparison of the groups.

RESULTS

There were significant differences of hypotension and lipid change between ESE and RSE (p<0.05). However, there was no significant difference between RSE-P and RSE-O groups. The hospital days were longer in RSE than in ESE (p=0.012) and treatment outcome was also worse in RSE than in ESE (p=0.007) but there were no significant differences of hospital stays and treatment outcome between RSE-P and RSE-O.

CONCLUSIONS

RSE is very critical disease with high mortality, which may show as many clinical changes as propofol infusion syndrome. Therefore propofol infusion syndrome might be considered as one of the clinical manifestations of RSE.

A comparative study of non-lipid nanoemulsion of propofol with solutol and propofol emulsion with lecithin

BACKGROUND AND OBJECTIVES

Some formulations have been proposed to reduce the adverse reactions due to the lipid emulsion containing soybean oil used as propofol carrier. This study for endoscopy sedation was aimed at evaluating and comparing the safety, effectiveness and adverse effects of the use of propofol nanoemulsion compared to propofol currently commercialized.

METHOD

In this prospective study, 150 patients were submitted to upper digestive endoscopy. These patients were allocated into two groups: the control group (CONT Group; n=75) and the nanoemulsion group (NE Group; n=75). HR, SBP, DBP, SpO(2) and BIS (which is considered to be appropriate between 65 and 75 during procedure) were monitored. Gender, age, weight, height, BMI, ASA physical status, times and doses were analyzed, as well as adverse effects (phlogistic signs and pain on injection, apnea, nausea/vomiting) and alterations in monitoring variables. A p-value < 0.05 was considered significant.

RESULTS

The groups had similar results concerning anthropometric data and physical status. None of the patients developed apnea or presented phlogistic signs in the injection site. The incidence of pain on injection in the CONT Group was 82.7% and 53.3% in the NE Group (p<0.001), and the incidence of nausea and vomiting was 10.7% in the CONT Group and 2.7% in the NE Group (p>0.05). The times, induction doses and the SBP and DBP values at the end of examination and at the moment of discharge from the PACU were lower in the NE Group (p<0.05).

CONCLUSIONS

Lipid propofol and propofol nanoemulsion were equivalent concerning effectiveness, safety and adverse effects in the doses used. There was a lower incidence of pain on injection in the nanoemulsion formulation.

The use of propofol sedation in a paediatric intensive care unit

BACKGROUND

The aim of this study was to prospectively evaluate and report the experience of the use of continuous intravenous propofol sedation in a paediatric intensive care unit (PICU).

METHODS

All children younger than 16 years who were admitted to the PICU at a University Hospital for slightly more than a year and received propofol infusion were included prospectively and data were recorded before and within 6 h after completion of the propofol infusion.

RESULTS

A total of 174 out of 955 children (18·2%) received propofol infusion for sedation. The median age was 2 years 10 months (range: 2 months to 16 years), duration of propofol infusion 13 h (range: 1·6-179 h) and dose of propofol 2·9 mg/kg/h (range: 0·3-6·5 mg/kg/h). No one developed signs of the propofol infusion syndrome (PRIS). Neither dose >3 mg/kg/h, duration of infusion >48 h nor both were found to be related to adverse metabolic derangements or circulatory failure. Eight children increased their lactate concentration ≥1·8 mmol/L during propofol infusion. All had a favourable outcome. One child who had received propofol infusion for 10 h died, but this occurred 14 h after the infusion ceased and was without doubt attributed to a multiple organ failure not related to the propofol infusion.

CONCLUSION

Propofol infusion was used in this population at low risk of PRIS with no metabolic or circulatory adverse effects. These findings indicate that the occurrence of adverse effects may not be directly related to dose or duration of infusion, but emphasizes the risk that sporadic factors may be involved, such as genetic mutations. Guidelines are presented.

Intensive care unit management of patients with stroke

Patients admitted with the diagnosis of "stroke" have a variety of different disorders that require specific treatment approaches in the critical care unit. Early thrombolysis for ischemic stroke and improvements in surgical and neurointerventional techniques for the treatment of aneurysms and arteriovenous malformations in patients with subarachnoid hemorrhage have been milestones in the past decade, but the evolvement of general management principles in critical care and the dedication of neurointensivists are equally important for improved outcomes. Strategies, which have been developed in other areas of intensive care medicine (eg, in patients with septic shock, acute respiratory distress syndrome, or trauma), need to be adopted and modified for the stroke patient. Prevention of iatrogenic complications and nosocomial infections is of utmost importance and requires sufficient numbers of trained personnel and high-quality equipment. Although the focus of attention in stroke patients is "brain resuscitation," comorbidities often limit the diagnostic and therapeutic options, and overall cardiopulmonary and metabolic functions need to be optimized in order to prevent secondary injury and allow the brain to recover. As part of a holistic approach to the rehabilitation process, psychologic and spiritual support for the patient must start early on in the intensive care unit, and family members should be involved in the patient's care and provided with special support as well.

Is There a Relationship between Hyperkalemia and Propofol?

This is a case of a sudden cardio-pulmonary arrest in a 29 year-old female, which occurred immediately after a large bolus infusion of propofol (100 mg) intravenously during dilatation and curettage. The arrest suddenly occurred, and the patient was eventually transferred to our emergency room (ER) on cardiopulmonary resuscitation. At that time, severe hyperkalemia up to 9.1 mEq/L and ventricular fibrillation were noted. Resuscitation in ER worked successfully with conversion of electrocardiograph to sinus rhythm, but this patient expired unfortunately. On view of this acute event immediately after the bolus injection of propofol accompanied without other identified causes, severe hyperkalemia induced by propofol was strongly assumed to be the cause of death. To our understanding with the literature survey, propofol as a cause of hyperkalemia has not been well described yet. Through this case, the relationship as a cause and an effect between propofol and hyperkalemia is suggested.

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.

Review of propofol and auxiliary medications used for sedation

The sedative-hypnotic propofol (2,6-diisopropylphenol) is being increasingly used for sedation during painful diagnostic and therapeutic procedures in adults and children. The purpose of this article is to present a general overview of the use of propofol for endoscopic sedation. Advantages and disadvantages of using propofol for sedation, as well as its pharmacokinetics, preparation for use, dosing for endoscopic sedation, auxiliary sedative and analgesic medication options, methods of administering, adverse effects with interventions, recovery, and patient-physician satisfaction are discussed. Finally, next steps necessary to optimize future use of propofol are suggested.

Analgesia and sedation for painful interventions in children and adolescents

BACKGROUND

Painful procedures on children and adolescents often have to be performed with the aid of analgesia and sedation in order to prevent pain and emotional distress. Moreover, many procedures can be performed more rapidly and more effectively in a relaxed patient. Because the combination of analgesia and sedation can cause serious or even life-threatening complications, it must be accompanied by the same safety precautions as a general anesthetic.

METHODS

Selective review of the literature.

RESULTS

A high level of safety can be achieved by adherence to the published guidelines of the societies for anesthesiology and pediatrics. The depth of sedation during procedures performed under combined analgesia and sedation is often equivalent to that resulting from general anesthesia. Therefore, in order to avoid serious complications, combined analgesia and sedation should only be administered by physicians trained in pediatric anesthesia or pediatric critical care. This is particularly so when propofol is used, because it has a narrow therapeutic range and can cause cardiorespiratory respiratory problems without warning. As long as the appropriate safety precautions are followed, non-anesthesiologists can also administer propofol in combination with an analgesic, such as ketamine, to children and adolescents.

CONCLUSION

In children and adolescents, the combination of analgesia and sedation can prevent the emotional trauma that would result from a painful procedure, while often enhancing the quality of the procedure itself. This method should be considered a variant of general anesthesia. Accordingly, any non-anesthesiologist employing this method must be as well versed as an anesthesiologist in the management of its specific side effects and complications.

The propofol infusion syndrome: more puzzling evidence on a complex and poorly characterized disorder

The propofol infusion syndrome is a potentially devastating cardiovascular and metabolic derangement that has been described in both pediatric and adult patients sedated with propofol. Despite a large number of case reports that have appeared in the literature since 1992, the precise clinical features and pathophysiology of this disorder remain uncertain. Historically, the syndrome has been characterized by the occurrence of lactic acidosis, rhabdomyolysis, and circulatory collapse after several days of high-dose propofol infusion. The affected patients were typically young and critically ill, and the reported mortality was high. More recently, a number of atypical cases have been reported with favorable outcomes. These occurred after short-term or lower-dose infusions in noncritically ill patients in whom generally only a subset of the classical syndrome features was observed. It remains unclear whether these reports reflect true propofol infusion syndrome detected at an earlier and more salvageable stage, or mere associations with the use of sedative agents in general. Without better information on the true incidence of the propofol infusion syndrome, clinical guidelines on the safe use of this drug remain unsupported by good evidence.

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.

Attenuation of propofol tolerance conferred by remifentanil co-administration does not reduce propofol toxicity in rabbits under prolonged mechanical ventilation

BACKGROUND

Prolonged sedation with propofol at high doses may lead to fatal multi-organ dysfunction, know as propofol infusion syndrome. We tested the hypothesis that propofol plus remifentanil co-administration attenuates propofol tolerance to its sedative effect and assessed if such an effect has an impact on propofol toxicity in rabbits under prolonged mechanical ventilation.

MATERIALS AND METHODS

Eighteen healthy male rabbits were mechanically ventilated and received propofol (group P, n = 6), propofol plus remifentanil (group PR, n = 6), or remifentanil plus sevoflurane (group RS, n = 6) in order to be kept under sedation (group P) or sedation/analgesia (groups PR and RS) for up to 48 h. Initial propofol and remifentanil infusion rates (IRs) were adjusted, if needed, to maintain the desired level of sedation and analgesia, respectively (groups P and PR). In group RS, remifentanil was infused at IRs equivalent to those of group PR. Propofol IRs were recorded, propofol concentrations were measured in the arterial plasma, and blood biochemical parameters and organ histopathology were assessed.

RESULTS

Animals survived for 29-36 h in group P and 22-38 h in group PR (100% mortality rate). Tolerance was developed to propofol's sedative effect. The onset of tolerance was delayed and its magnitude was decreased in group PR compared with group P. Propofol was accumulated in the systemic circulation. Propofol clearance rate was gradually decreased. Arterial lactate, and serum aspartate aminotransferase (AST), lactate dehydrogenase (LDH), bilirubin, cholesterol, triglycerides, and creatine kinase (CK) levels were increased. The heart, lungs, liver, gallbladder, kidneys, urinary bladder, and skeletal muscles were seriously injured in groups P and PR. In group RS, mortality was 0%, while there was only mild injury of the lungs, liver, gallbladder, kidneys, and urinary bladder.

CONCLUSIONS

Although propofol tolerance is attenuated in propofol plus remifentanil receiving rabbits under prolonged mechanical ventilation, fatal multi-organ injury occurs resembling human propofol infusion syndrome.

Propofol infusion syndrome

Propofol (Diprivan) is an intravenous sedative hypnotic that is used in the induction and maintenance of anesthesia and sedation. High-dose infusions have been associated with several serious adverse effects and, when combined, they are known as propofol infusion syndrome (PRIS). Although PRIS is rare, it is frequently fatal if not identified early. The purpose of this article is to raise practitioner awareness to this syndrome, with recommendations for early identification, prevention, and treatment of 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.

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.

Metabolic acidosis in the critically ill: part 2. Causes and treatment

The correct identification of the cause, and ideally the individual acid, responsible for metabolic acidosis in the critically ill ensures rational management. In Part 2 of this review, we examine the elevated (corrected) anion gap acidoses (lactic, ketones, uraemic and toxin ingestion) and contrast them with nonelevated conditions (bicarbonate wasting, renal tubular acidoses and iatrogenic hyperchloraemia) using readily available base excess and anion gap techniques. The potentially erroneous interpretation of elevated lactate signifying cell ischaemia is highlighted. We provide diagnostic and therapeutic guidance when faced with a high anion gap acidosis, for example pyroglutamate, in the common clinical scenario 'I can't identify the acid--but I know it's there'. The evidence that metabolic acidosis affects outcomes and thus warrants correction is considered and we provide management guidance including extracorporeal removal and fomepizole therapy.

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.