Chest
Volume 137, Issue 4, April 2010, Pages 777-782
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Original Research
Critical Care Medicine
Involuntary Cough Strength and Extubation Outcomes for Patients in an ICU

https://doi.org/10.1378/chest.07-2808Get rights and content

Background

Removing the artificial airway is the last step in the mechanical ventilation withdrawal process. In order to assess cough effectiveness, a critical component of this process, we evaluated the involuntary cough peak flow (CPFi) to predict the extubation outcome for patients weaned from mechanical ventilation in ICUs.

Methods

One hundred fifty patients were weaned from ventilators, passed a spontaneous breathing trial (SBT), and were judged by their physician to be ready for extubation in the Tri-Service General Hospital ICUs from February 2003 to July 2003. CPFi was induced by 2 mL of normal saline solution at the end of inspiration and measured using a hand-held respiratory mechanics monitor. All patients were then extubated.

Results

Of 150 enrolled patients for this study, 118 (78.7%) had successful extubation and 32 (21.3%) failed. In the univariate analysis, there were higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores (16.0 vs 18.5, P = .018), less negative maximum inspiratory pressure (−45.0 vs −39.0, P = .010), lower cough peak flows (CPFs) (74.0 vs 42.0 L/min, P < .001), longer postextubation hospital stays (15.0 vs 31.5 days, P < .001), and longer postextubation ICU stays (1.0 vs 9.5 days, P < .001) in the extubation failures compared with the extubation successes. In the multivariate analysis, we found that a higher APACHE II score and a lower CPF were related to increasing risk of extubation failure (odds ratio [OR] = 1.13; 95% CI, 1.03-1.25; and OR = 0.95; 95% CI, 0.93-0.98, respectively). The receiver operator characteristic curve cutoff point for CPF was 58.5 L/min, with a sensitivity of 78.8% and specificity of 78.1%.

Conclusions

CPFi as an indication of cough reflex has the potential to predict successful extubation in patients who pass an SBT.

Section snippets

Patients

Three hundred four patients on mechanical ventilation in tertiary intensive care units at Tri-Service General Hospital from January 2003 through December 2003 were evaluated for the study. From this group we recruited 150 patients who had been ventilated for ≥ 3 days, had passed a 2-h SBT, and were judged by their physician to be ready for extubation. The reasons for excluding the other 154 patients are summarized in Figure 1.

Internal Review Board

The weaning guidelines specified by our weaning and extubation

Results

Of the 150 patients eligible for this study, 118 (78.7%) were successfully extubated, and 32 (21.3%) patients failed extubation. Table 1 summarizes the demographics and clinical features of these 150 patients. Univariate logistic regression analysis was used to explore the correlation between variables and extubation failure status (Table 1). Patients who failed extubation had lower CPFi (range [minimum, maximum]: 42 [21,112] L/min vs 74 [19,138], P < .001), higher APACHE II scores (χ2 = 8.32,

Discussion

Extubation failure increases hospital mortality in patients in ICUs7, 8, 9, 10, 11 and prolongs mechanical ventilation, ICU stay, and hospital stay.6, 7, 12 We also found longer ICU stays in our extubation failures. In our multivariate analysis, we demonstrated that involuntary CPF and APACHE II were the primary predictors of extubation success in critically ill patients who passed an SBT.

Cough is defined as deep inspiration followed by strong expiration against a closed glottis, which then

Acknowledgments

Author contributions: Dr W.-L. Su: contributed to designing the study and writing the protocol, managing literature searches and analyses, and writing the first draft of the manuscript.

Dr Y.-H. Chen: contributed to managing the literature searches and analyses.

Dr C.-W. Chen: contributed to designing the study and writing the protocol.

Mr Yang: contributed to statistical analysis.

Ms C.-L. Su: contributed to statistical analysis.

Dr Perng: contributed to managing literature searches and analyses.

Dr

References (0)

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    Previous studies have demonstrated that CPEF is a competent indicator for predicting successful extubation in patients undergoing SBT. Patients with CPEF < 60 L/min were five times more likely to fail extubation (Smina et al., 2003; Su et al., 2010). In these studies, the mean duration of mechanical ventilation was 3.4–4.0 days, comparable to the ventilator days for our SMV group (2.1 days), but much shorter than those for the PMV group (33.8 days).

  • The use of cough peak flow in the assessment of respiratory function in clinical practice- A narrative literature review

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    In the literature, CPF values of above 160 l/min at the mouth or above 60 l/min measured at the level of the endotracheal tube were shown to predict successful extubation. In addition, there was an association with reduced length of stay in ICU, expenditure and morbidity and mortality which merits further research [57]. The use of CPF has also been used in predicting the successful decannulation of a tracheotomy tube in neurosurgical patients [58].

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