Respiratory depression under long-term sedation with sufentanil, midazolam and clonidine has no clinical significance.

OBJECTIVE: Assessment of respiratory depression caused by long-term sedation with sufentanil, midazolam and clonidine.

DESIGN: Retrospective assessment using data from a patient data management system.

SETTING: University hospital anaesthesiological ICU.

PATIENTS: Three hundred ninety-five surgical and trauma patients with an ICU stay of more than 48 h.

INTERVENTION: None.

MEASUREMENTS AND RESULTS: Arterial blood partial pressure of carbon dioxide (PCO2) was evaluated during mechanically assisted spontaneous ventilation (continuous positive airway pressure, synchronised intermittent mandatory ventilation, mandatory minute ventilation, bilevel positive airway pressure). Continuous sedation with sufentanil, midazolam or clonidine or a combination of those drugs was administered to achieve a Ramsay score between 2 and 4. Spontaneously breathing patients without continuous sedation and patients on controlled mechanical ventilation (and sedation) served as control groups. Mean arterial PCO2 from spontaneously breathing patients without continuous sedation was 39.5 +/- 7.3 torr compared with 42.7 +/- 6.8 torr under sufentanil (median 0.44 microg x kg(-1) x h(-1), 98 % of observations between 0.1 and 2.1 microg x kg(-1) x h(-1)), 41.5 +/- 6.1 torr under sufentanil (median 0.90 microg x kg(-1) x h(-1) (0.1-2.8)) plus midazolam (median 45 microg x kg(-1) x h(-1) (7-170)) and 39.8 +/- 5.6 torr under a combination of sufentanil (median 1.15 microg x kg(-1) x h(-1) (0.2-3.6)), midazolam (median 45 microg x kg(-1) x h(-1) (11-216)) and clonidine (median 1.3 microg x kg(-1) x h(-1) (0.2-2.5)). Mean arterial PCO2 from patients on controlled mechanical ventilation was 39.9 +/- 6.1 torr.

CONCLUSION: Patients under continuous sedation with sufentanil exhibit a statistically significant rise in arterial PCO2, however this respiratory depression is only slight and has no clinical significance. Mechanically assisted spontaneous ventilation modes can safely be used under continuous sedation with sufentanil, midazolam or clonidine.