EFFECT OF UNPLANNED EXTUBATION ON OUTCOME OF MECHANICAL VENTILATION

	To the Editor :

I read with interest the paper by Epstein and colleagues (1) regarding the outcome of unplanned extubation (UE). I have had a long-standing interest in this subject (2) and would like to comment on what I think is a skewed approach to the problem. Various studies have looked at different aspects of the problem, including predictors of UE, predictors of reintubation, outcome of UE, etc. Unfortunately, most of these studies have had relatively high rate of UE and this most basic aspect of UE is either not commented upon, or is viewed as an inevitable aspect of translaryngeal intubation. The current study had a UE rate of 11% per patient and 1.6% per intubated day. Another study also published in 2000 (6) also had UE rates of 11.4-17.1% per patient and 1.51-2.47% per intubated day. These high rates are found in much of the literature (1, 2). Compare this with the situation in Australia where, in 1998-1999, the Australian Council on Health Care standards recorded an UE rate of 119 incidents over 29,652 intubated days (0.4%) (5). Anecdotally, UE rates in the UK (3, 5) and Sweden (5) too are very low. Our experience is similar (2). Over 4 years (1994-1997) we recorded UE rates of 0.71% per patient and 0.39% per intubated day, respectively. This incidence was similar to that of 0.68% and 0.32% in the next two years (1998-1999). It is particularly instructive to read the experiences of medical and nursing personnel who have had the opportunity to work in different continents, as this clearly explains the marked difference in the UE rates (5). Unlike Epstein, who used physical restraints liberally in agitated patients, other ICUs that have recorded these low UE rates do not resort to physical restraint as a means of preventing UE. Does the physical restraint actually decrease UE, or does it worsen patient agitation and increase UE? The literature is equivocal.

Although the authors conclude that UE is not associated with increased mortality, they should note that in one particular study (7) the authors recorded 24 incidents of UE in 53 patients in which three incidents directly resulted in death. This gives a mortality of 5.7% directly as a consequence of UE. UE is a potentially fatal complication, and the best way to prevent any associated mortality is to ensure that the UE does not occur.

I believe that when viewing the problem of UE in the context of improving standards of critical care, statistical analysis regarding predictors of UE, predictors of reintubation, or predictors of mortality is not the way forward. Instead, each UE should be viewed as an individual incident, in an attempt at analyzing why such an incident was allowed to occur in the first place. Our experience showed that 50%-78% (2) of airway accidents were either completely or partly preventable. Focusing on individual incidents especially with respect to nursing supervision, adequate securing of the endotracheal tube, adequate sedation and appropriately early weaning is usually all that is required to keep UE rates below 0.5% per intubated day.

Hinduja National Hospital and Medical Research Center, Mumbai, India

1. Epstein S, Nevins ML, Chung J. Effect of unplanned extubation on outcome of mechanical ventilation. Am J Respir Crit Care Med 2000; 161: 1912-1916 [Abstract/Free Full Text].

2. Kapadia F, Bajan KB, Raje K. Airway accidents in intubated ICU patients: an epidemiological study. Crit Care Med 2000; 28: 659-666 [Medline].

3. Kapadia F. Accidental tracheal extubation. Lancet 1998; 352: 1633 [Medline].

4. Kapadia F. Unplanned extubations. Chest 1995; 108: 1768-1769 .

5. Kapadia F. Airway accidents in ICU. (Cybernet: http://ccm-1.med.edu/farhad.html). Ind J Critical Care Medicine 2000; 4: 59-68 .

6. Carrion MI, Ayuso D, Marcos M, Paz Robles M, de la Cal MA, Alia I, Esteban A. Accidental removal of endotracheal and nasogastric tubes and intravascular catheters. Crit Care Med 2000; 28: 63-66 [Medline].

7. Amato MB, Barbas CS, Medeiros DM, Magaldi RB, Schettino GP, Lorenzi-Filho G, Kairalla RA, Deheinzelin D, Munoz C, Oliveira R, et al . . Effect of a protective ventilation strategy on mortality in acute respiratory distress syndrome. N Eng J Med 1998; 338: 347-354 [Abstract/Free Full Text].

	From the Authors :

I agree with Dr. Kapadia that a skewed analysis of the unplanned extubation literature is not the best way to proceed. A review of the peer-reviewed literature clearly demonstrates that unplanned extubation is a frequent event when studying medical, general surgical, or multidisciplinary ICU patient populations (1). In these studies, with a minimum mean duration of mechanical ventilation of three days (range 3-11 days), 3 to 16% of patients experienced at least one episode of unplanned extubation. In contrast, Kapadia and colleagues, in an uncontrolled study, observed an extraordinarily low unplanned extubation rate among their ICU population, more than 75% of whom were cardiac surgery patients (2). Although the low rate was attributed to a specific prevention strategy, the authors failed to account for the impact of their unique case mix, with a mean duration of mechanical ventilation less than two days. Patients requiring such a short duration of ventilation are unlikely to have high severity of illness, require ICU procedures that have a tendency to lead to accidental extubation, or have the opportunity to experience self-extubation.

After controlling for APACHE II, comorbid conditions, age, sex, and indication for mechanical ventilation in a medical ICU, we demonstrated that unplanned extubation resulted in a prolonged duration of mechanical ventilation, ICU stay and hospital stay and increased the need for postacute care among survivors (3). Our results highlight the need to focus on prevention of unplanned extubation among mechanically ventilated populations frequently encountered by ICU practitioners. One possible way of reducing the incidence of unplanned extubation is to apply "adequate" chemical sedation (2). Unfortunately there is accumulating evidence that aggressive sedation policies can lead to prolonged duration of mechanical ventilation, ICU and hospital stay and need for tracheostomy (4). Therefore, before advocating specific prevention strategies, investigators should conduct properly controlled studies in the ICU populations at highest risk for unplanned extubation.

Tufts University School of Medicine, Boston, Massachusetts

1. Epstein SK. Endotracheal extubation. Respir Care Clin N Am 2000; 6: 321-360 . [Medline]

2. Kapadia FN, Bajan KB, Raje KV. Airway accidents in intubated intensive care unit patients: an epidemiological study. Crit Care Med 2000; 28: 659-664 .

3. 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 .

4. Brook AD, Ahrens TS, Schaiff R, Prentice D, Sherman G, Shannon W, Kollef MH. Effect of a nursing-implemented sedation protocol on the duration of mechanical ventilation. Crit Care Med 1999; 27: 2609-2615 [Medline].

5. Kollef MH, Levy NT, Ahrens TS, Schaiff R, Prentice D, Sherman G. The use of continuous i.v. sedation is associated with prolongation of mechanical ventilation. Chest 1998; 114: 541-548 [Abstract/Free Full Text].

6. Kress JP, Pohlman AS, O'Connor MF, Hall JB. Daily interruption of sedative infusions in critically ill patients undergoing mechanical ventilation. N Engl J Med 2000; 342: 1471-1477 [Abstract/Free Full Text].