Planned and unplanned postoperative admissions to critical care for mechanical ventilation

To determine which factors influence the clinician in choosing critical care admission and postoperative ventilation, we prospectively examined the incidence, timing, causes, and risk factors for admission to critical care for postoperative ventilation within 48 hr of a surgical procedure (excluding cardiac and neurosurgical).

Patients were categorized as: admission planned preoperatively; admission unplanned and identified in the OR (Operating Room) or PACU (Post Anaesthetic Care Unit); and admission unplanned, identified after PACU discharge. Rates of admission by category for those with specific preoperative and intraoperative characteristics were compared to those without the characteristics to determine risk factors for admission (P < 0.01).

Only 329 of 15,059 cases (2.2%) had a critical care admission. Of these, 288 were planned, 31 identified in the OR or PACU, and 10 after PACU discharge. A respiratory aetiology was the reason for admission in 75% of unplanned cases. Preoperatively, age > or = 60 yr and common systemic illnesses (cardiac, renal, pulmonary) were markers for planned admission, but only positive HIV status was a risk factor for unplanned admission. The two main physiological features which identified all critical care admissions were haemoglobin oxygen saturation < 90% (preoperatively breathing room air and intraoperatively) and tachycardia during the operative period. Six of ten of the unplanned after PACU discharge patients underwent bronchoscopy with a neurolept analgesic technique.

Postoperative admissions to a critical care unit, both planned and unplanned, are uncommon. This study has identified haemoglobin oxygen desaturation during the perioperative period and intraoperative tachycardia as important markers for all admissions to critical care.