Peak expiratory flow in mechanically ventilated patients under three modalities of manually assisted coughing

Introduction

Bronchopulmonary hygiene physical therapy refers to techniques that promote clearance of airway secretion. One of these techniques is manually assisted coughing (MAC), which could be applied unilaterally, bilaterally or thoracic–abdominally. The first research about MAC was published in 1966; nevertheless, until now, no study has tried to compare the three different forms of applying this technique. Studies about MAC have just analysed the effects of secretion clearance on oxygenation. The aim of this study was therefore to compare the peak expiratory flow (PEF) produced by MAC when accomplished in different application forms, in mechanically ventilated patients.

Design

A prospective, experimental and blinded study.

Methods

Twenty-six patients (mean age 60 ± 13.5 years) admitted to the Hospital Português Clinical–Surgery Intensive Care Unit requiring controlled mechanical ventilation and with positive end expiratory pressure of 5.5 ± 1.44 cmH₂O were assessed. Patients with a history of pulmonary disease, hemodynamic instability, rib cage and/or abdominal abnormalities, scoliosis, pregnancy, obesity, a cardiac pacemaker, pneumothorax, unstable thorax and positive end expiratory pressure higher than 10 cmH₂O were excluded. The PEF was measured by the Navigator Graphics Monitor (Newport Medical Instruments Inc., Newport Beach, CA, USA). MAC was performed five times in each hand position (unilateral, bilateral and abdominal–thoracic) in an alleatory way, with intervals of three breathings between each application of the technique. The Mann–Whitney rank-sum test was used to compare the groups. Differences with P < 0.05 were considered significant.

Results

Means of PEF variations are presented in Table 1. When comparing the different modalities of MAC, no statistical significant differences were noted.

Table 1

Conclusion

MAC was efficient to increase the PEF in all tested modalities. Nevertheless, these results confirm that the efficacy was no different between the modalities, suggesting that it is a personal choice involving the patient and the therapist on the moment of technique performance.