Effectiveness of dexmedetomidine versus propofol on extubation times, length of stay and mortality rates in adult cardiac surgery patients: a systematic review and meta-analysis
Authors: Nguyen John , Nacpil Noel 
Published: May 2018

ABSTRACT

Objective:
To determine the effects of dexmedetomidine versus propofol on extubation time, intensive care unit (ICU) length of stay, total hospital length of stay and in-hospital mortality rates in cardiac surgery patients.

Introduction:
Recovery from cardiovascular surgery involves weaning from mechanical ventilation. Mechanical ventilation decreases the work of breathing for patients by inhaling oxygen and exhaling carbon dioxide via a ventilator or breathing machine. Prolonged mechanical ventilation is associated with complications, such as pneumonia and lung injury, and increases the risk of morbidity and mortality. Major risk factors that contribute to lung injury are due to high tidal volumes and barotrauma. Cardiac surgery patients remain on the ventilator postoperatively due to the high dose opioid-based anesthesia and the initial vulnerable hemodynamic state. An important component of postoperative management following cardiac surgery is the use of sedation to reduce the stress response, facilitate assisted ventilation, and provide anxiolysis. Propofol and dexmedetomidine are two common sedative agents with differing pharmacological profiles used to provide comfort and minimize hemodynamic disturbances during this recovery phase. Choice of drug may have an impact on length of mechanical ventilation, length of stay and mortality.

Inclusion criteria:
Participants included were ≥18 years, of any gender or ethnicity, undergoing valvular surgery, coronary artery bypass graft (CABG) surgery, or valvular surgery and CABG. Studies were excluded if participants received both dexmedetomidine and propofol concurrently as a primary sedative. Interventions were propofol compared to dexmedetomidine as continuous infusions for sedation after cardiac surgery. All variations of dosages and duration of both sedative agents were included. Outcomes of interest were: total time (hours) of mechanical ventilation after cardiac surgery, specifically from end of surgery to extubation; total length of stay (LOS) in the ICU (hours) following cardiac surgery, specifically from ICU admission to transfer to medical ward; total hospital LOS (hours) following cardiac surgery, from date of admission to date of discharge; and in-hospital mortality rates, from date of admission to date of discharge. Randomized controlled trials (RCTs), controlled trials, and prospective and retrospective cohort studies were considered for inclusion.

Methods:
A search was conducted in MEDLINE via PubMed, Embase, Trip Database, ProQuest Nursing and Allied Health Source Database, Web of Science, ProQuest Dissertations and Theses Global, and MedNar to locate both published and unpublished studies between January 1, 1999 and November 23, 2017. Two reviewers assessed the methodological quality using standardized critical appraisal instruments from the Joanna Briggs Institute System for the Unified Management, Assessment and Review of Information (JBI SUMARI). Quantitative data were extracted using the standardized data extraction tool from JBI SUMARI. Data were pooled using Comprehensive Meta-Analysis Software Version 3 (Biostat, NJ, USA). Mean differences (95% confidence interval [CI]) and effect size estimates were calculated for continuous outcomes. Meta-analysis using a random-effects model was performed for length of mechanical ventilation, ICU LOS, and hospital LOS. Results have been presented in narrative form when findings could not be pooled using meta-analysis. Standard GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) evidence assessment of outcomes has been reported.

Results:
A total of four studies were included in the review. Meta-analysis of three cohort studies revealed dexmedetomidine to be superior to propofol with an average reduction of 4.18 hours (95% CI −6.69 to −1.67, p = 0.001) on the extubation times, an average 9.89 hour (95% CI −18.6 to −1.19, p = 0.03) reduction in ICU LOS, and an average 37.9 hour (95% CI, −60.41 to −15.46, p = 0.00) reduction in overall hospital LOS. A RCT was excluded from pooling for meta-analysis, but its results were congruent with meta-analysis results. There was lack of sufficient data to perform meta-analysis on in-hospital mortality rates.

Conclusions:
In postoperative cardiac surgery patients, dexmedetomidine is associated with a shorter time to extubation, shorter ICU LOS, and shorter hospital LOS in postoperative cardiac surgery patients compared to propofol. The quality of evidence for these findings however is low and no recommendations can be made to change current practice. There was insufficient evidence to determine significant differences in-hospital mortality rates. Sedation protocols still need to be formulated.
There are significant gaps in the literature. Areas of further research include additional well-designed and appropriately powered RCTs with wide inclusion criteria to reflect this surgical population; quantitative, transparent, and standardized sedation, weaning, and extubation protocols; precise and standardized methods and measurements for interventions and outcomes, and short- and long-term morbidity and mortality follow-up.