What Is the Optimal Time to Perform Tracheostomy?
Abstract & Commentary
By Andrew M. Luks, MD, Pulmonary and Critical Care Medicine, University of Washington, Seattle, is Associate Editor for Critical Care Alert.
Dr. Luks reports no financial relationship to this field of study.
Synopsis: This retrospective cohort analysis demonstrates that patients who receive tracheostomy within the first 10 days of critical illness have a small, yet statistically significant, mortality benefit compared to those who undergo tracheostomy at a later point in time, but provides no insight into factors governing patient selection for early timing of the procedure.
Source: Scales DC, et al. The effect of tracheostomy timing during critical illness on long-term survival. Crit Care Med 2008;36:2547-2557.
Tracheostomy confers patient benefits such as decreasing laryngeal irritation, improving patient communication, and decreasing sedation requirements, but the optimal timing of this procedure in critically ill patients remains a subject of considerable debate. Scales and colleagues conducted a retrospective cohort study to determine whether performing tracheostomy earlier in the course of critical illness was associated with improvements in patient survival.
The authors examined the Ontario Health Databases to identify all critically ill patients who underwent tracheostomy across multiple centers over a 12-year period (1992 to 2004). Patients were excluded from the analysis if they underwent tracheostomy within 48 hours or after 28 days of initiating mechanical ventilation. The major independent variable in the analysis was the timing of tracheostomy. This was treated as a continuous variable, but they also conducted analyses in which it was treated as a dichotomous variable in which tracheostomy was defined as being "early" if it occurred between 3 and 10 days after initiation of mechanical ventilation and "late" if it occurred between 11 and 28 days following mechanical ventilation. The 10-day cutoff was selected based on the results of prior observational studies, which showed that the median time to tracheostomy is 9-14 days. The primary outcome measure was the hazard of dying after initiation of mechanical ventilation. Secondary outcomes included 90-day and 1-year mortality, time from tracheostomy to discontinuation of mechanical ventilation, ICU length of stay, and ventilator-free days at 28 at 180 days. All survivors were followed for between 1 and 13 years (median, 6.4 years).
A total of 10,927 patients were included in the analysis; 3758 (34%) of the patients underwent "early" tracheostomy while 7169 (66%) underwent a "late" procedure. There were important differences between the two groups as the early tracheostomy patients were older, had more cardiac disease, and more physician visits prior to their ICU admission, while the late tracheostomy group was less likely to have a neurologic disorder or traumatic injury. Overall, 7219 (66%) of patients died during the study period. Cumulative mortality was lower in the early tracheostomy group at 90 days (34.8% vs 36.9%; P = 0.03), one year (46.5% vs 49.8%; P = 0.001), and during the entire study period (63.9% vs 67.2%; P < 0.001). Multivariable analyses in which tracheostomy was treated as a time-dependent variable demonstrated that each additional 1-day delay in tracheostomy was associated with increased mortality (hazard ratio, 1.008; 95% confidence interval, 1.004-1.012). Patients receiving early tracheostomy had more ventilator-free days than the late tracheostomy patients at both 28 (mean number, 9.7 vs 3.0; P < 0.001) and 90 (mean, 94.2 vs 81.2; P < 0.001) days and faster weaning from mechanical ventilation (7 vs 13 days).
The results of this study are intriguing but should not leave anyone running for the percutaneous tracheostomy kit and bronchoscope just yet. Although there was a mortality benefit to early tracheostomy at 90 days, at one year, and over the entire study period, the absolute reductions were very small and likely only reached statistical significance because of the very large sample size. More importantly, it must be remembered that this was a retrospective study and, as a result, the authors were unable to control for important variables such as the reasons patients underwent tracheostomy at particular times. In fact, the Ontario Health Database that served as the foundation of this study did not include such information. To their credit, they did use multiple analyses to adjust for unmeasured confounding variables and these analyses consistently showed a small mortality benefit to early tracheostomy. However, as they admit themselves in the discussion and as was revealed in some of the demographic data about the early and late groups (e.g., the percentage of people with cardiac disease or neurologic injury), it is likely that there are systematic differences between the two groups that limit the applicability of these results. Rather than interpreting their results as indicative of a mortality benefit to early tracheostomy, I would argue that the very small differences observed in this study suggest we are probably not doing our patients any harm by waiting longer to see if they can get off the ventilator and then doing tracheostomy if they fail attempts at weaning.
Beyond the issue of whether the timing of tracheostomy affects mortality, there was one other particularly striking feature of the data; more than 30% of patients, regardless of the timing of their tracheostomy, died within 90 days of the procedure, while up to 67% of patients died within the study period, which lasted in some cases up to 13 years. These are surprisingly high numbers and suggest that the need for tracheostomy in critical illness portends an overall poor long-term prognosis for the patient.