Comparison of cough peak expiratory flow measurement and cough strength measurement using the white card test in extubation success A randomized controlled trial

Failed extubation and subsequent re‑intubation in ventilated patients can lead to many adverse consequences, including organizational and personal expenditures. Extubation decisions based on subjective methods are a major contributor to extubation failure. This study compared the effect of cough peak expiratory flow (PEF) measurement and cough strength measurement using the white card test (WCT) on extubation success.

This randomized clinical trial was conducted in two groups in 2018 on 88 ventilated patients in intensive care units of Imam Reza Hospital in Mashhad, Iran. Ninety patients were divided into two groups of 45, but two were excluded from the white card group. The criteria established for extubation included PEF ≥60 L/ min during coughing in the cough PEF group and noticing card humidity in the WCT group. In both groups, extubation success was determined as the sole outcome and was compared with the standard PEF and cough strength. The researcher who assessed the outcome and statistician were blinded about group allocation.

Extubation success was measured as 97.8% in the cough PEF group and 76.7% in the WCT group (P = 0.003) during the first 24 h. In the second 24 h, however, successful extubation was reported as 90.9% in the cough PEF group and 60.6% in the WCT group (P = 0.002).

Using the cough PEF rate increases the likelihood of extubation success and reduces adverse effects, and is recommended to be used for extubation decision‑making.