[Propofol infusion syndrome]

Metabolic Profiles of Propofol and Fospropofol: Clinical and Forensic Interpretative Aspects

Propofol is an intravenous short-acting anesthetic widely used to induce and maintain general anesthesia and to provide procedural sedation. The potential for propofol dependency and abuse has been recognized, and several cases of accidental overdose and suicide have emerged, mostly among the health professionals. Different studies have demonstrated an unpredictable interindividual variability of propofol pharmacokinetics and pharmacodynamics with forensic and clinical adverse relevant outcomes (e.g., pronounced respiratory and cardiac depression), namely, due to polymorphisms in the UDP-glucuronosyltransferase and cytochrome P450 isoforms and drugs administered concurrently. In this work the pharmacokinetics of propofol and fospropofol with particular focus on metabolic pathways is fully reviewed. It is concluded that knowing the metabolism of propofol may lead to the development of new clues to help further toxicological and clinical interpretations and to reduce serious adverse reactions such as respiratory failure, metabolic acidosis, rhabdomyolysis, cardiac bradyarrhythmias, hypotension and myocardial failure, anaphylaxis, hypertriglyceridemia, renal failure, hepatomegaly, hepatic steatosis, acute pancreatitis, abuse, and death. Particularly, further studies aiming to characterize polymorphic enzymes involved in the metabolic pathway, the development of additional routine forensic toxicological analysis, and the relatively new field of ‘‘omics” technology, namely, metabolomics, can offer more in explaining the unpredictable interindividual variability.

Association of preservative-free propofol use and outcome in critically ill patients

BACKGROUND

Propofol is widely used to provide sedation to patients in the intensive care unit (ICU). This study examined whether preservative-free propofol infusion independently influences outcome in critically ill patients.

METHODS

This was a nested cohort study within a randomized controlled trial. ICU patients who received preservative-free propofol and those who did not were compared. The following data were collected: demographic information, APACHE II score, admission category, chronic severe illnesses, nutritional data, and blood glucose level and insulin dose. The main exposure was the use of preservative-free propofol infusion. The main outcomes were the occurrence of ICU-acquired infections, ICU-acquired sepsis, and ICU and hospital mortality.

RESULTS

A total of 523 patients were included (no propofol group, n = 399; propofol group, n = 124). After adjustment for differences in baseline characteristics, preservative-free propofol use was associated with increased risk of ICU-acquired infections (adjusted odds ratio [aOR], 1.89, 95% confidence interval [CI], 1.17-3.06; P = .009) and ICU-acquired severe sepsis and septic shock (aOR, 1.91; 95% CI, 1.12-3.28; P = .02), but not with ICU or hospital mortality.

CONCLUSION

Preservative-free propofol infusion in critically ill patients may be associated with increased risk of ICU-acquired infections and ICU-acquired sepsis, with no significant difference in ICU or hospital mortality. This association might have been related to the use of preservative-free preparations.

[Long-term therapy with propofol has no impact on microcirculation in medical intensive care patients]

BACKGROUND

Microcirculation has become a major focus of research in critical care medicine due to its growing clinical relevance detecting changes in organ perfusion at an early stage. A negative impact of propofol infusion on microcirculation during short-term anesthesia was described recently. The influence of long-term sedation with propofol on microflow of critical care patients is still unclear.

PATIENTS AND METHODS

Microflow was analyzed using sidestream darkfield microscopy of sublingual mucosa in 28 patients of whom eleven received continuous infusion of propofol. According to current guidelines, microflow was recorded digitally. Quantitative analysis was performed offline in a semiquantitative way (0: no flow; 1: intermittent flow; 2: sluggish flow; 3: continuous flow).

RESULTS

Good microflow rates were detected in sublingual vessels (10-100 microm) in hemodynamically stable, medical intensive care patients. In the majority of cases, continuous flow profiles were recorded. There was no difference in flow rates between patients with and without propofol therapy.

CONCLUSION

In hemodynamically stable intensive care patients, long-term therapy with propofol did not affect sublingual microflow in this small cohort. However, intensive care physicians should keep such possible interactions in mind avoiding administration of these substances in patients with manifested shock. The effects of propofol in hemodynamically impaired patients should be evaluated in further studies.

Propofol infusion syndrome in adult cardiac surgery

We report a case of rapid and progressive severe metabolic acidosis in the postoperative period after coronary artery bypass grafting. After exclusion of potential causes for this phenomenon, it was attributed to perioperative intravenous propofol infusion causing propofol infusion syndrome. We discontinued this intravenous agent resulting in a prompt and considerable improvement in the lactic acidosis and clinical condition in the subsequent 6 hours resulting in an uneventful recovery and hospital discharge.

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.