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29-06-2011 | Anaesthesiology | Article

Risk index predicts unanticipated postoperative intubation


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MedWire News: Researchers have developed a risk index to predict unanticipated early postoperative intubation (UEPI) in patients undergoing nonemergent noncardiac surgery.

The study, which appears in the journal Anesthesiology, also demonstrates a high risk for death among patients who undergo UEPI.

Satya-Krishna Ramachandran (University Hospital, Ann Arbor, Michigan, USA) and colleagues based their index on data from 222,094 patients in the American College of Surgeons-National Surgical Quality Improvement Program database.

UEPI within 30 days of surgery occurred in 0.83% of this cohort, and about half of these procedures occurred within 3 days of the operation.

The researchers identified 17 independent predictors of UEPI within 3 days of surgery; the strongest of these were medium-, high-, and very-high-risk surgery, which raised the odds of UEPI 2.2-, 2.6-, and 5.3-fold relative to low-risk surgery.

Other predictors were alcohol use, current smoking, being underweight or class III obese, having dyspnea, chronic obstructive pulmonary disease, diabetes, congestive heart failure, hypertension, abnormal liver function, cancer, or sepsis, or experiencing prolonged hospitalization or weight loss. These factors raised the risk for UEPI between 1.3- and 1.6-fold.

Together, the 17 predictors were 77% accurate for distinguishing between patients who did and did not undergo UEPI.

Ramachandran et al then divided the patients into six groups based on the number of risk factors they had for UEPI. This ranged from zero or one factor in risk class I to six or more in class V. The rates of UEPI were 0.2%, 0.5%, 1.0%, 1.9%, and 3.7% among patients in risk classes I, II, III, IV, and V, respectively. There was a similar pattern in a validation cohort of 109,636 patients.

UEPI had a major effect on mortality risk, report the researchers. They matched 979 patients with UEPI to 979 without for multiple risk factors including the 17 in the risk index. After matching, the 30-day rate of all-cause mortality was 15.0% among patients with UEPI, compared with just 1.9% among those without.

The effect on mortality extended to patients considered at low risk for UEPI, with mortality rates of 9.7% versus 0.2% among matched patients in risk class I with and without UEPI, respectively. The corresponding rates among patients in risk class V were 30.6% versus 9.5%.

"These data may provide an opportunity to target patients with high risk class for identification of specific interventions that may improve outcomes," say Ramachandran and team.

"This may involve developing triggers for early postoperative noninvasive ventilation," they say, citing a study that showed a 10-fold reduction in tracheal intubation if patients were given continuous positive airway pressure early after abdominal surgery.

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Eleanor McDermid