Key Point

Patients who experience an unplanned extubation in the ICU may experience a survival benefit, provided that they do not require reintubation.

STAMFORD, CONN—Unplanned extubation (UE) occurs in approximately 1% to 14% of patients receiving mechanical ventilation. These extubations have widely varying effects on morbidity and mortality. To date, only three studies have examined the long-term health consequences of UEs in a case-control manner.

Recently, researchers at Stamford Hospital in Connecticut, a major teaching affiliate of the Columbia University College of Physicians and Surgeons, performed a case-control study of 100 patients with UEs compared with 200 control patients who received mechanical ventilation without UE. They found that UE was associated with increased lengths of both hospital and ICU stay—but decreased mortality. The mortality benefit was entirely explained by the subgroup (56 out of 100 patients) who did not require reintubation.¹

“My ICU has weaning protocols in place that prospectively identify patients on a regular basis who may be suitable for liberation from mechanical ventilation,” said lead author James S. Krinsley, MD, FCCP, Director of Critical Care at Stamford Hospital and Associate Clinical Professor of Medicine at Columbia University College of Physicians and Surgeons. “Even with these guidelines in place,” he continued, “some patients experience unplanned extubation, either due to airway accidents (eg, the tube slips out during patients’ repositioning in bed) or, more commonly, because of willful behavior on the part of the patients.”

The Stamford Hospital ICU (where the study took place) has a detailed database documenting all patients admitted to the ICU. The database tracks demographic, acuity, and outcome parameters for each patient and is updated daily.

The study group consisted of 100 patients admitted to the ICU between June 27, 1999, and September 3, 2003, who experienced UE. Two control patients matched for gender, age, and APACHE II score were found for each study patient. Two subgroups were identified from the main study group: those who required reintubation within 48 hours of UE and those who did not.

During the study period, there were 1,515 separate episodes of mechanical ventilation in 1,473 patients. Thus, the 100 patients with UE yielded an incidence rate of 6.6%. The median age of the entire population undergoing mechanical ventilation during the study period was 72. The median APACHE II score was 22.

Of the 100 UE patients, 44 required reintubation and 56 did not. “Multiple stepwise logistic regression analysis identified age as the only pre-UE factor that predicted the need for reintubation,” said Dr. Krinsley. “The patients who required reintubation either had upper airway problems (stridor, excessive secretions) or worsening respiratory failure—usually hypoxic—after the UE event.”

REINTUBATION PREDICTS POOR OUTCOMES

Interestingly, although UE resulted in longer hospital and ICU stays, as well as a longer duration of mechanical ventilation, the ICU and hospital mortality of the UE group was significantly lower than that of the control group. These findings can be explained by comparing the outcomes in UE patients who required reintubation versus the outcomes in those who did not. Specifically, UE patients who required reintubation had markedly longer ICU and hospital stays and longer duration of mechanical ventilation. In addition, the group requiring reintubation had a fivefold greater incidence of hospital mortality and significantly more infections while in the ICU.

However, a comparison of the UE patients who did not require reintubation versus the control group showed no significant differences in age, gender, race, admitting circumstances, or APACHE II scores. Neither did lengths of ICU or hospital stay differ. However, there was a substantial difference in hospital mortality: 7.8% of the UE group not requiring reintubation died, compared to 35% of the control group. Mortality in the control group was similar to that in the UE patients who required reintubation.

This study—the largest case-control study of its kind in the literature—demonstrated that patients who underwent UE were more likely to survive to hospital discharge. This survival benefit was entirely attributable to the UE patients who did not require reintubation. The authors noted that the lack of a need for reintubation in some UE patients may help identify patients for whom planned extubation has been delayed.

Two previous studies compared outcomes of patients with UEs to those of controls. In one study, by Epstein et al,2 56% of the UE patients required reintubation. Of these, 40% died, compared with 21% of patients who did not require reintubation and 28% of controls who were successfully weaned. In a study by Atkins and colleagues,3 74% of UE patients required reintubation and 51% of these patients died, compared with none of the UE patients who did not require reintubation. The need for reintubation was associated with the apparent increase in mortality among UE patients in both the Epstein and Atkins studies.

CANDIDATES FOR EARLIER WEANING?

The authors of the present study suggested that “patients who undergo UE and do not require reintubation may actually have better outcomes than do patients receiving [mechanical ventilation] without UE.” They added that this may be a result of an accelerated weaning process in those not requiring reintubation or that these patients may be physiologically better equipped to survive after UE.

“It is mandatory to prospectively and regularly identify patients who may be ready for planned extubation,” Dr. Krinsley emphasized. “There was a profound difference in outcome among patients with unplanned extubation who did not require reintubation (7% mortality—a remarkably low value for patients with a mean APACHE II score of 22) compared to those with unplanned extubation who did require reintubation (35% mortality).”

—Gale Jurasek

Reference
1. Krinsley JS, Barone JE. The drive to survive: unplanned extubation in the ICU. Chest. 2005;128:560-566.
2. Epstein SK, Nevins ML, Chung J. Effect of unplanned extubation on outcome of mechanical ventilation. Am J Respir Crit Care Med. 2000;161:1912-1916.
3. Atkins PM, Mion LC, Mendelson W, et al. Characteristics and outcomes of patients who self-extubate from ventilatory support: a case-control study. Chest. 1997;112:1317-1323.

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