Remifentanil dosage in critically ill patients is independent of organ dysfunction

Introduction

Continuous analgo-sedation of ICU patients with established opioids is difficult due to unfavorable pharmaco-kinetics, especially in patients with major organ dysfunctions. Remifentanil (RF) is more suitable for these patients because of its short half-life independent of the duration of the preceding infusion and organ functions. No large observational study has investigated the influence of multiple organ dysfunctions and old age on the dosage and duration of RF infusion in critically ill patients.

Methods

Set in a general surgical ICU of a university hospital. Within 28 months, 876 postoperative patients requiring ventilation received analgo-sedation with a constant low-dose propofol infusion (1.5 mg/kg/hour) and a variable continuous RF infusion to a target Ramsay Sedation Score 2–3, until either ventilatory withdrawal was initiated or sedation regimen was changed after 48 hours. The hourly dosage and total duration of RF infusion, and the SOFA score were documented. Potential predictors for RF dosage were evaluated by univariate and subsequent stepwise multiple regression analysis. Significance was set at P < 0.05.

Results

The median (± IQR) SOFA score was 7 ± 4, infusion duration 16 ± 12 hours, age 70 ± 29 years, mean (± SD) RF dosage 87 ± 44 ng/kg/min. Neither the total SOFA score or any single composite organ dysfunction influenced the dosage of RF infusion (Table 1). However, older patients needed considerably smaller RF dosages. Patients with multiple organ dysfunction had prolonged infusion duration, but no change in dosage. After discontinuation of RF infusion, all patients were awake and extubated within 1–2 hours.

Table 1

Conclusion

In critically ill ventilated postoperative patients, even multiple severe organ dysfunctions do not alter the dosage of continuous RF infusion. Due to predictable pharmacokinetic properties and reliably short extubation times, RF may be the most adaptable and safest choice for these patients. Actual dosages necessary to provide appropriate analgo-sedation are lower and therefore less costly than expected, especially in older patients. Further studies to evaluate a cost–benefit ratio and to afford dosage recommendations for RF analgo-sedation in ICU patients are warranted.