Altered Pharmacokinetics in Prolonged Infusions of Sedatives and Analgesics Among Adult Critically Ill Patients: A Systematic Review

Practical approach to inhaled sedation in the critically ill patient. Sedation, analgesia and Delirium Working Group (GTSAD) of the Spanish Society of Intensive and Critical Care Medicine and Coronary Units (SEMICYUC)

The use of sedatives in Intensive Care Units (ICU) is essential for relieving anxiety and stress in mechanically ventilated patients, and it is related to clinical outcomes, duration of mechanical ventilation, and length of stay in the ICU. Inhaled sedatives offer benefits such as faster awakening and extubation, decreased total opioid and neuromuscular blocking agents (NMB) doses, as well as bronchodilator, anticonvulsant, and cardiopulmonary and neurological protective effects. Inhaled sedation is administered using a specific vaporizer. Isoflurane is the recommended agent due to its efficacy and safety profile. Inhaled sedation is recommended for moderate and deep sedation, prolonged sedation, difficult sedation, patients with acute respiratory distress syndrome (ARDS), status asthmaticus, and super-refractory status epilepticus. By offering these significant advantages, the use of inhaled sedatives allows for a personalized and controlled approach to optimize sedation in the ICU.

Potential pharmacological confounders in the setting of death determined by neurologic criteria: a narrative review

Guidelines for the determination of death by neurologic criteria (DNC) require an absence of confounding factors if clinical examination alone is to be used. Drugs that depress the central nervous system suppress neurologic responses and spontaneous breathing and must be excluded or reversed prior to proceeding. If these confounding factors cannot be eliminated, ancillary testing is required. These drugs may be present after being administered as part of the treatment of critically ill patients. While measurement of serum drug concentrations can help guide the timing of assessments for DNC, they are not always available or feasible. In this article, we review sedative and opioid drugs that may confound DNC, along with pharmacokinetic factors that govern the duration of drug action. Pharmacokinetic parameters including a context-sensitive half-life of sedatives and opioids are highly variable in critically ill patients because of the multitude of clinical variables and conditions that can affect drug distribution and clearance. Patient-, disease-, and treatment-related factors that influence the distribution and clearance of these drugs are discussed including end organ function, age, obesity, hyperdynamic states, augmented renal clearance, fluid balance, hypothermia, and the role of prolonged drug infusions in critically ill patients. In these contexts, it is often difficult to predict how long after drug discontinuation the confounding effects will take to dissipate. We propose a conservative framework for evaluating when or if DNC can be determined by clinical criteria alone. When pharmacologic confounders cannot be reversed, or doing so is not feasible, ancillary testing to confirm the absence of brain blood flow should be obtained.

The use of dexmedetomidine in the emergency department: A systematic review

BACKGROUND

Dexmedetomidine (DEX), a centrally acting alpha-2 agonist, is increasingly used for sedation in multiple clinical settings. Evidence from the intensive care unit and operative settings suggests DEX may have significant advantages over traditional GABAergic sedatives such as benzodiazepines. There has been limited research on the use of DEX in the emergency department (ED).

METHODS

We performed a systematic review of the medical literature to identify all published evidence regarding the use of DEX in the ED. We included randomized and nonrandomized studies and studies reporting any use of DEX in the ED, even when it was not the primary focus of the study. Two authors reviewed studies for inclusion, and a single author assessed studies for quality and risk of bias and abstracted data.

RESULTS

We identified 35 studies meeting inclusion criteria, including 11 randomized controlled trials, 13 cohort and other nonrandomized studies, and 11 case reports and case series. Significant heterogeneity in interventions, comparators, indications, and outcomes precluded data pooling and meta-analysis. We found modest evidence that DEX was efficacious in facilitating medical imaging and mixed and limited evidence regarding its efficacy for procedural sedation and sedation of nonintubated medical and psychiatric patients. Our results suggested that DEX is associated with bradycardia and hypotension, which are generally transient and infrequently require medical intervention.

CONCLUSIONS

A limited body of generally poor- to moderate-quality evidence suggests that the use of DEX may be efficacious in certain clinical scenarios in the ED and that DEX use in the ED is likely safe. Further high-quality research into DEX use in the ED setting is needed, with a particular focus on clear and consistent selection of indications, identification of clear and clinically relevant primary outcomes, and careful assessment of the clinical implications of the hemodynamic effects of DEX therapy.

Pharmacokinetic Alterations Associated with Critical Illness

Haemodynamic, metabolic, and biochemical derangements in critically ill patients affect drug pharmacokinetics and pharmacodynamics making dose optimisation particularly challenging. Appropriate therapeutic dosing depends on the knowledge of the physiologic changes caused by the patient's comorbidities, underlying disease, resuscitation strategies, and polypharmacy. Critical illness will result in altered drug protein binding, ionisation, and volume of distribution; it will also decrease oral drug absorption, intestinal and hepatic metabolism, and renal clearance. In contrast, the resuscitation strategies and the use of vasoactive drugs may oppose these effects by leading to a hyperdynamic state that will increase blood flow towards the major organs including the brain, heart, kidneys, and liver, with the subsequent increase of drug hepatic metabolism and renal excretion. Metabolism is the main mechanism for drug clearance and is one of the main pharmacokinetic processes affected; it is influenced by patient-specific factors, such as comorbidities and genetics; therapeutic-specific factors, including drug characteristics and interactions; and disease-specific factors, like organ dysfunction. Moreover, organ support such as mechanical ventilation, renal replacement therapy, and extracorporeal membrane oxygenation may contribute to both inter- and intra-patient variability of drug pharmacokinetics. The combination of these competing factors makes it difficult to predict drug response in critically ill patients. Pharmacotherapy targeted to therapeutic goals and therapeutic drug monitoring is currently the best option for the safe care of the critically ill. The aim of this paper is to review the alterations in drug pharmacokinetics associated with critical illness and to summarise the available evidence.

Gabapentin to treat acute alcohol withdrawal in hospitalized patients: A systematic review and meta-analysis

BACKGROUND

Gabapentin is an antiepileptic medication with evidence of benefit in alcohol use disorder patients. The mechanism of action of gabapentin may also benefit patients suffering from acute alcohol withdrawal syndrome (AWS).

METHODS

A systematic review and meta-analysis were conducted to examine if gabapentin can effectively replace/reduce the use of benzodiazepines for the treatment of acute alcohol withdrawal symptoms in hospitalized patients. Time to alcohol withdrawal symptom resolution, amount of benzodiazepines administered, rate of resolution of alcohol withdrawal symptoms, serious withdrawal-related complications, and hospital length of stay (LOS) were examined.

RESULTS

Eight retrospective studies (n = 2030) were included in this meta-analysis. There were no studies that examined study outcomes for patients who received only gabapentin and no benzodiazepines; in all studies, gabapentin-treated patients may have received benzodiazepines prior to gabapentin. There were no significant differences between gabapentin-treated and benzodiazepine-treated groups in time to symptom resolution, amount benzodiazepines administered, withdrawal-related complications, or LOS. There was a significant difference in the rate of symptom resolution favoring gabapentin-treated patients (p = 0.05); however, this analysis included only one study. Subgroup analyses of severe AWS patients revealed a significant decrease in LOS (p = 0.04) and a decrease in amount of benzodiazepines administered (p = 0.02) in gabapentin-treated patients, but these analyses included only one study. Subgroup analysis of patients receiving only gabapentin without benzodiazepines found a significantly decreased LOS in the gabapentin group compared to the benzodiazepine group (p < 0.001), but this analysis included only two studies.

CONCLUSIONS

There is insufficient evidence to support the widespread use of gabapentin to treat inpatients suffering AWS. All studies included in this meta-analysis are retrospective with high risk of confounding. Well-designed, randomized, controlled studies of gabapentin to treat patients with AWS are required.

Identifying encephalopathies from acute metabolic derangements

Metabolic derangements, when acute and severe, affect brain function. This presents mostly with a marked decline in the level of consciousness, resulting in impaired responsiveness, abnormal receptivity, impaired content, and loss of memory retention. The term metabolic encephalopathy has been used but is conjecture that can be challenged in the age of modern neuroimaging. We now recognize that many metabolic encephalopathies may involve structural lesions and at an early stage. Common clinical conundrums are the evaluation of the degree of brain injury and its recoverability. This review discusses the appropriate terminology for these conditions, the diagnostic approach, therapy recommendations, and prediction of recovery potential. In evaluating a presumed metabolic cause for encephalopathy, we must (1) search for and rule out structural injury to the brain despite an obvious explanatory metabolic derangement, (2) recognize that several confounding conditions often co-exist, and (3) acknowledge that resolution of brain dysfunction may be protracted despite normalization of laboratory values.

Monitoring of sedation in mechanically ventilated patients using remote technology

PURPOSE OF REVIEW

Two years of coronavirus disease 2019 (COVID-19) pandemic highlighted that excessive sedation in the ICU leading to coma and other adverse outcomes remains pervasive. There is a need to improve monitoring and management of sedation in mechanically ventilated patients. Remote technologies that are based on automated analysis of electroencephalogram (EEG) could enhance standard care and alert clinicians real-time when severe EEG suppression or other abnormal brain states are detected.

RECENT FINDINGS

High rates of drug-induced coma as well as delirium were found in several large cohorts of mechanically ventilated patients with COVID-19 pneumonia. In patients with acute respiratory distress syndrome, high doses of sedatives comparable to general anesthesia have been commonly administered without defined EEG endpoints. Continuous limited-channel EEG can reveal pathologic brain states such as burst suppression, that cannot be diagnosed by neurological examination alone. Recent studies documented that machine learning-based analysis of continuous EEG signal is feasible and that this approach can identify burst suppression as well as delirium with high specificity.

SUMMARY

Preventing oversedation in the ICU remains a challenge. Continuous monitoring of EEG activity, automated EEG analysis, and generation of alerts to clinicians may reduce drug-induced coma and potentially improve patient outcomes.

Isoflurane promotes early spontaneous breathing in ventilated intensive care patients: A post hoc subgroup analysis of a randomized trial

BACKGROUND

Spontaneous breathing is desirable in most ventilated patients. We therefore studied the influence of isoflurane versus propofol sedation on early spontaneous breathing in ventilated surgical intensive care patients and evaluated potential mediation by opioids and arterial carbon dioxide during the first 20 h of study sedation.

METHODS

We included a single-center subgroup of 66 patients, who participated in a large multi-center trial assessing efficacy and safety of isoflurane sedation, with 33 patients each randomized to isoflurane or propofol sedation. Both sedatives were titrated to a sedation depth of -4 to -1 on the Richmond Agitation Sedation Scale. The primary outcome was the fraction of time during which patients breathed spontaneously.

RESULTS

Baseline characteristics of isoflurane and propofol-sedated patients were well balanced. There were no substantive differences in management or treatment aside from sedation, and isoflurane and propofol provided nearly identical sedation depths. The mean fraction of time spent spontaneously breathing was 82% [95% CI: 69, 90] in patients sedated with isoflurane compared to 35% [95% CI: 22, 51] in those assigned to propofol: median difference: 61% [95% CI: 14, 89], p < .001. After adjustments for sufentanil dose and arterial carbon dioxide partial pressure, patients sedated with isoflurane were twice as likely to breathe spontaneously than those sedated with propofol: adjusted risk ratio: 2.2 [95%CI: 1.4, 3.3], p < .001.

CONCLUSIONS

Isoflurane compared to propofol sedation promotes early spontaneous breathing in deeply sedated ventilated intensive care patients. The benefit appears to be a direct effect isoflurane rather than being mediated by opioids or arterial carbon dioxide.

Differential Effects of Gamma-Aminobutyric Acidergic Sedatives on Risk of Post-Extubation Delirium in the ICU: A Retrospective Cohort Study From a New England Health Care Network

OBJECTIVES

To evaluate whether different gamma-aminobutyric acidergic (GABAergic) sedatives such as propofol and benzodiazepines carry differential risks of post-extubation delirium in the ICU.

DESIGN

Retrospective cohort study.

SETTING

Seven ICUs in an academic hospital network, Beth Israel Deaconess Medical Center (Boston, MA).

PATIENTS

Ten thousand five hundred and one adult patients mechanically ventilated for over 24 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We tested the hypothesis that benzodiazepine versus propofol-based sedation is associated with fewer delirium-free days within 14 days after extubation. Further, we hypothesized that the measured sedation level evoked by GABAergic drugs is a better predictor of delirium than the drug dose administered. The proportion of GABAergic drug-induced deep sedation was defined as the ratio of days with a mean Richmond Agitation-Sedation Scale of less than or equal to -3 during mechanical ventilation. Multivariable regression and effect modification analyses were used. Delirium-free days were lower in patients who received a high proportion of deep sedation using benzodiazepine compared with propofol-based sedation (adjusted absolute difference, -1.17 d; 95% CI, -0.64 to -1.69; p < 0.001). This differential effect was magnified in elderly patients (age > 65) and in patients with liver or kidney failure (p-for-interaction < 0.001) but not observed in patients who received a low proportion of deep sedation (p = 0.95). GABAergic-induced deep sedation days during mechanical ventilation was a better predictor of post-extubation delirium than the GABAergic daily average effective dose (area under the curve 0.76 vs 0.69; p < 0.001).

CONCLUSIONS

Deep sedation during mechanical ventilation with benzodiazepines compared with propofol is associated with increased risk of post-extubation delirium. Our data do not support the view that benzodiazepine-based compared with propofol-based sedation in the ICU is an independent risk factor of delirium, as long as deep sedation can be avoided in these patients.

Effects of modified multimodal analgesia on postoperative pain, sedation, and prognosis of gynecological patients

Patient-controlled intravenous analgesia is one of the most common pain relief methods in  the postoperative period, but its adverse reactions remain high. This study aimed to explore the role of improved combined analgesia methods in pain, sedation, postoperative nausea, and vomiting (PONV) in patients undergoing gynecological surgeries. This study was a prospective, randomized, double-blind controlled study. A study population of 72 patients undergoing gynecological surgery were randomly assigned to either the TAPB + S group or the TAPB + N group. All patients in both groups underwent a transversus abdominis plane block (TAPB) after induction of anesthesia. The TAPB + S group received a continuous intravenous infusion (2 ml/h) of sufentanil (1 μg/kg) plus metoclopramide (30 mg) through 100 ml elastomeric pumps postoperatively. The TAPB + N group received a continuous intravenous infusion (2 ml/h) of nalbuphine hydrochloride (1 mg/kg) plus metoclopramide (30 mg) postoperatively. The main outcome measures were as follows: postoperative pain intensity, Ramsay sedation score (RSS) after surgery, PONV occurrence rate, and rescue analgesics. The RSS of the TAPB + S group was significantly higher than that of the TAPB + N group at 2, 4, and 6 h after the operation. However, the visual analog scale score of the TAPB + S group was much higher than that of the TAPB + N group. No significant differences were found between the two groups in terms of consumption of opioids and other narcotic drugs at 2, 4, 6, 24, and 48 h after the operation. No statistically significant differences were found with respect to PONV and other adverse events in both groups. Taken together, our data indicate that the TAPB + N program can provide better postoperative analgesia and also reduce the use of strong opioids. The more optimized scheme of perioperative analgesia still needs to be researched further.

Management of Sedation and Analgesia in Critically Ill Patients Receiving Long-Acting Naltrexone Therapy for Opioid Use Disorder

The explosion of the opioid epidemic in the United States and across the world has been met with advances in pharmacologic therapy for the treatment of opioid use disorder. Long-acting naltrexone is a promising strategy, but its use has important implications for critical care, as it may interfere with or complicate sedation and analgesia. Currently, there are two available formulations of long-acting naltrexone, which are distinguished by different administration routes and distinct pharmacokinetics. The use of long-acting naltrexone may be identified through a variety of strategies (such as physical examination, laboratory testing, and medical record review), and is key to the safe provision of sedation and analgesia during critical illness. Perioperative experience caring for patients receiving long-acting naltrexone informs management in the intensive care unit. Important lessons include the use of multimodal analgesia strategies and anticipating patients' demonstrating variable sensitivity to opioids. For the critically ill patient, however, there are important distinctions to emphasize, including changes in drug metabolism and medication interactions. By compiling and incorporating the currently available literature, we provide critical care physicians with recommendations for the sedation and analgesia for critically ill patients receiving long-acting naltrexone therapy.

Protein Binding and Population Pharmacokinetics of Dexmedetomidine after Prolonged Infusions in Adult Critically Ill Patients

PURPOSE

Dexmedetomidine (DEX) is a highly selective α₂-adrenoceptor agonist with high protein binding of 94%. Critical illness may affect protein binding and the pharmacokinetic (PK) parameters of many drugs, including DEX. In critically ill patients receiving prolonged infusions of DEX, there is little information documenting the relationship between key pathophysiologic factors and DEX protein binding or PK parameters. The purpose of this study was to characterize the protein binding and PK profile of prolonged DEX infusion in critically ill patients.

METHODS

Critically ill, adult intensive care unit patients at a university hospital in Hong Kong were studied. The association between the pathophysiologic changes of critical illness and protein binding was evaluated using a generalized estimating equation. A population pharmacokinetic model to establish the PK profile of DEX was developed, and key pathophysiologic covariate effects of severity of illness, organ dysfunction measures, and altered protein binding on DEX PK parameters in this critically ill population were evaluated.

FINDINGS

A total of 22 critically ill patients and 1 healthy control were included. Mean protein binding of DEX in the critically ill patients was 90.4% (95% CI, 89.1-91.7), which was 4% lower than that in the healthy control. The PK data were adequately described by a 2-compartment model. The estimated population mean (relative standard error [RSE]) values of systemic clearance (CL), volume of distribution of the central compartment (V2), intercompartmental clearance (Q), and V_d in the peripheral compartment (V3) were 38.6 (11.7) L/h, 32.1 (46.1) L, 114.5 (58.3) L/h and 95.1 (30.6) L, respectively. The corresponding estimated interindividual variability expressed as CV% (RSE) was 52.4 (23.8) for CL, 172.9 (19.3) for V2, 123.7 (33.7) for Q, and 106 (39.9) for V3. No significant explanatory pathophysiologic covariates were identified.

IMPLICATIONS

Although a marginally significant reduction of protein binding in critically ill patients was demonstrated, the magnitude of the difference was unlikely to be of clinical significance. Higher alanine aminotransferase concentration was associated with decreased protein binding. No significant pathophysiologic covariates were associated with the observed PK parameters. The high interindividual variability of PK parameters supports the current practice of dose titration to ensure the desired clinical effects of DEX infusion in the intensive care unit setting.

Current status of perioperative hypnotics, role of benzodiazepines, and the case for remimazolam: a narrative review

Anaesthesiologists and non-anaesthesiologist sedationists have a limited set of available i.v. hypnotics, further reduced by the withdrawal of thiopental in the USA and its near disappearance in Europe. Meanwhile, demand for sedation increases and new clinical groups are using what traditionally are anaesthesiologists' drugs. Improved understanding of the determinants of perioperative morbidity and mortality has spotlighted hypotension as a potent cause of patient harm, and practice must be adjusted to respect this. High-dose propofol sedation may be harmful, and a critical reappraisal of drug choices and doses is needed. The development of remimazolam, initially for procedural sedation, allows reconsideration of benzodiazepines as the hypnotic component of a general anaesthetic even if their characterisation as i.v. anaesthetics is questionable. Early data suggest that a combination of remimazolam and remifentanil can induce and maintain anaesthesia. Further work is needed to define use cases for this technique and to determine the impact on patient outcomes.

Analgesia and Sedation in Critically Ill Adult Patients Admitted to a COVID-19 Intensive Care Unit

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing the COVID-19 has spread globally, prompting world health organization (WHO) to declare COVID-19 a pandemic. As of January 2, 2021, about 82,579,768 laboratory-confirmed COVID-19 cases had been reported to the WHO with 1,818,849 deaths (https://covid19.who.int). The pandemic has severely impacted health care systems around the world, resulting in a vast number of surgical procedures being cancelled or postponed and an unprecedented burden on intensive care units (ICU). A critical component of the perioperative or ICU services delivery is the provision of analgesia and sedation. Volatile inhalational anesthetics combined with opioids are widely used in an operating room, whereas in ICUs, intravenous drugs are used for this purpose. Although target-controlled infusions are not routinely used in ICUs, in the context of the thematic series on total intravenous anesthesia during COVID-19 pandemic, this article will focus on key aspects of intravenous sedation and analgesia in the management of critically ill patients admitted to an ICU following positive swab test for SARS-CoV-2 RNA.

Development and validation of a liquid chromatography coupled to tandem mass spectrometry method for the simultaneous quantification of five analgesics and sedatives, and six of their active metabolites in human plasma: Application to a clinical study on the determination of neurological death in the intensive care unit

A sensitive and selective high-performance liquid chromatographic method coupled to tandem mass spectrometry was developed and validated for the quantification of morphine, hydromorphone, fentanyl, midazolam and propofol and their metabolites morphine-3-β-d-glucuronide, morphine-6-β-d-glucuronide, hydromorphone-3-β-d-glucuronide, 1'-hydroxymidazolam-β-d-glucuronide, α-hydroxymidazolam and 4-hydroxymidazolam in human plasma using potassium oxalate/sodium fluoride mixture as anticoagulant. Human plasma samples (0.4 mL) to which were added a mixture of eleven deuterated internal standards were subjected to solid phase extraction using a mixed-mode polymeric Oasis PRiME MCX in 96-well format. Propofol was selectively eluted and further derivatized using 2-Fluoro-1-methylpyridinium p-toluenesulfonate, whereas the remaining 10 analytes were eluted separately and further concentrated. The derivatized propofol was analyzed separately in a second injection. The analytes were chromatographically separated on a Kinetex phenyl-hexyl analytical column in gradient elution mode, using a mobile phase consisting of aqueous ammonium formate/formic acid buffer and methanol. The overall run time was 8 min. Detection was performed using an AB/SCIEX 4000 QTRAP instrument with positive electrospray ionization employing scheduled multiple reaction monitoring mode. The lower limits of quantification ranged from 0.02 to 5 ng/mL depending on the analyte. Calibration curves covered a concentration range of 1000× in all cases but 1'-hydroxymidazolam-β-d-glucuronide where it covered a range of 500 × . The validated method was accurate and precise, the intra-day accuracy and precision of quality control samples (4 concentration levels, n = 6 each) being within 91.5-112 % and 1.3-13.2 % (coefficient of variation), respectively, and inter-day (n = 24; 4 days) accuracy and precision of quality control samples (3 concentration levels) being within 94.8-103.5 % and 3.2-11.2 % (coefficient of variation). Mean absolute extraction recoveries were above 60 % for all compounds, except for hydromorphone-3-β-d-glucuronide (44 %) and for 1'-hydroxymidazolam-β-d-glucuronide (33 %). Internal standard corrected matrix effect ranged from -4.8 to 3.8 % in normal plasma and in plasma containing 1 % hemolyzed blood. Analytes were stable (above 90 %) in plasma and blood for 19 h at 22 °C, in blood for 90 h at 5 °C, in plasma for 60 days at -20 °C, for 4 months at -70 °C and after three freeze-thaw cycles, and in the injection solvent for at least 3 days in the autosampler. The present method is successfully being applied in a multicenter clinical study for the analysis of plasma samples from patients in intensive care units from a number of Canadian hospitals.

Challenges in anaesthesia and pain management for burn injuries

Burn-injured patients provide unique challenges to those providing anaesthesia and pain management. This review aims to update both the regular burn anaesthetist and the anaesthetist only occasionally involved with burn patients in emergency settings. It addresses some aspects of care that are perhaps contentious in terms of airway management, fluid resuscitation, transfusion practices and pharmacology. Recognition of pain management failures and the lack of mechanism-specific analgesics are discussed along with the opioid crisis as it relates to burns and nonpharmacological methods in the management of distressed patients.

A pragmatic approach to intravenous anaesthetics and electroencephalographic endpoints for the treatment of refractory and super-refractory status epilepticus in critical care

Status epilepticus is a common neurological emergency, with overall mortality around 20%. Over half of cases are first time presentations of seizures. The pathological process by which spontaneous seizures are generated arises from an imbalance in excitatory and inhibitory neuronal networks, which if unchecked, can result in alterations in intracellular signalling pathways and electrolyte shifts, which bring about changes in the blood brain barrier, neuronal cell death and eventually cerebral atrophy. This narrative review focusses on the treatment of status epilepticus in adults. Anaesthetic agents interrupt neuronal activity by enhancing inhibitory or decreasing excitatory transmission, primarily via GABA and NMDA receptors. Intravenous anaesthetic agents are commonly used as second or third line drugs in the treatment of refractory status epilepticus, but the optimal timing and choice of anaesthetic drug has not yet been established by high quality evidence. Titration of antiepileptic and anaesthetic drugs in critically ill patients presents a particular challenge, due to alterations in drug absorbtion and metabolism as well as changes in drug distrubution, which arise from fluid shifts and altered protein binding. Furthermore, side effects associated with prolonged infusions of anaesthetic drugs can lead to multi-organ dysfunction and a need for critical care support. Electroencelography can identify patterns of burst suppression, which may be a target to guide weaning of intravenous therapy. Continuous elctroencephalography has the potential to directly impact clinical care, but despite its utility, major barriers exist which have limited its widespread use in clinical practice. A flow chart outlining the timing and dosage of anaesthetic agents used at our institution is provided.