The Future of Intensive Care Unit Sedation: A Report of Continuous Infusion Ketamine as an Alternative Sedative Agent

Continuous infusion ketamine for sedation of mechanically ventilated adults in the intensive care unit: A scoping review

Introduction

Mechanical ventilation (MV) is a common and often live-saving intervention on the Intensive Care Unit (ICU). The optimisation of sedation to mechanical ventilation is fundamental, and inappropriate sedation has been associated with worse outcomes. This scoping review has been designed to answer the question 'What is known about the use of ketamine as a continuous infusion to provide sedation in mechanically ventilated adults in the intensive care unit, and what are the gaps in the evidence?'

Methods

The protocol was designed using the PRISMA-ScR checklist and the JBI manual for evidence synthesis. Data were extracted and reviewed by a minimum of two reviewers.

Results

Searches of electronic databases (PubMed, OVID, Scopus, Web of Science) produced 726 results; 45 citations were identified for further eligibility assessment, an additional five studies were identified through keyword searches, and 12 through searching reference lists. Of these 62 studies, 27 studies were included in the final review: 6 case reports/case series, 11 retrospective cohort/observational studies, 1 prospective cohort study, 9 prospective randomised studies.

Conclusion

We found a lack of high-quality well-designed studies investigating the use of continuous ketamine sedation on ICU. The available data suggests this intervention is safe and well tolerated, however this is of very low certainty given the poor quality of evidence.

Temporal Trends and Variability in Ketamine Use for Mechanically Ventilated Adults in the United States

Rationale The epidemiology of continuous ketamine use in the management of critically ill adults receiving invasive mechanical ventilation (MV) in the U.S. is unknown. Objective To quantify the temporal trends and variation across U.S. hospitals in continuous ketamine use. Methods We performed a retrospective cohort study of adults (age ≥18) receiving MV who were discharged (alive or dead) from U.S. hospitals contributing data to the Premier Healthcare Database between January 2008 and September 2018. We used mixed effects multivariable logistic regression modeling (fixed effects: patient and hospital characteristics; random effect: discharge hospital) to evaluate the associations of discharge quarter and discharge hospital with continuous ketamine use (defined as a charge for intravenous ketamine on ≥2 consecutive calendar days). Results We identified 2,059,599 MV adults across 842 hospitals; of these, 7,927 (0.4%) received continuous ketamine. Ketamine use increased over time from 0.07% of all patients in quarter 1 2008 to 1.1% of all patients in quarter 3 2018. After adjustment, the odds of receiving continuous ketamine were consistently increased starting in quarter 4 2011 (odds ratio [95% confidence interval]: 1.83 [1.09-3.06] vs quarter 1 2008, p=0.023) with >10-fold increased odds starting in quarter 2 2017. Out of 842 hospitals, 486 (57.7%) used continuous ketamine on at least one cohort patient during the study period. Across these hospitals ever using ketamine, median use was 0.2% (IQR 0.08%-0.5%) with 5 hospitals using continuous ketamine in >5% of patients. The adjusted median odds ratio for discharge hospital was 3.72 (95% confidence interval: 3.37-4.13) which was higher than the odds ratio for any patient or hospital covariable other than discharge quarter. Conclusions In U.S. hospitals, use of continuous infusion ketamine increased markedly over time in critically ill patients receiving MV, with substantial variability between hospitals. Given the unique properties of ketamine as a sedative, further research is needed to assess its safety and utility in critically ill populations.

Alternatives to Rapid Sequence Intubation: Contemporary Airway Management with Ketamine

Endotracheal intubation (ETI) is a high-risk procedure commonly performed in emergency medicine, critical care, and the prehospital setting. Traditional rapid sequence intubation (RSI), the simultaneous administration of an induction agent and muscle relaxant, is more likely to harm patients who do not allow appropriate preparation and preoxygenation, have concerning airway anatomy, or severe hypoxia, acidemia, or hypotension. Ketamine, a dissociative anesthetic, can be used to facilitate two alternatives to RSI to augment airway safety in these scenarios: delayed sequence intubation - the use of ketamine to allow airway preparation and preoxygenation in the agitated patient; and ketamine-only breathing intubation, in which ketamine is used without a paralytic to facilitate ETI as the patient continues to breathe spontaneously. Ketamine may also provide hemodynamic benefits during standard RSI and is a valuable agent for post-intubation analgesia and sedation. When RSI is not an optimal airway management strategy, ketamine's unique pharmacology can be harnessed to facilitate alternative approaches that may increase patient safety.