Effectiveness and safety evaluation of a cough stimulation device in early postoperative respiratory rehabilitation in cardiac surgery patients

Abstract

To evaluate the effectiveness and safety of cough stimulation using the mechanical in- and exsufflator in the early postoperative period in cardiac surgery patients. The study included 37 patients; mean age was 57±12.3 years. Inclusion criteria: age over 18 years; post-extubation spontaneous breathing; fully conscious and cooperative; adequate gas exchange with oxygen therapy; adequate pain control (2 points or less on 10-point visual analogue scale). Exclusion criteria: need for re-intubation and mechanical ventilation; noninvasive mask ventilation; high-flow oxygen therapy; acute cerebrovascular event; uncontrolled bleeding; heart failure (inotropic score over 10); shock; need of extracorporeal blood purification; neuromuscular disease; pneumothorax, hydro- or hemothorax. Cough stimulation was performed using the mechanical in- and exsufflator Comfort Cough Plus («Seoil Pacific Corporation», Republic of Korea). The device provides cough stimulation after high-frequency vibrations transmitted through a special vest and lung tissue recruiting by changing the airways pressure of the gas mixture, delivered through the anesthesia face mask. Cough stimulation device use was associated with an increase in the cough effectiveness; the number of patients with productive cough increased 8-fold, from 4 (10.8%) to 32 (86.4%), p=0.0000. The increase of blood oxygen saturation (SpO2) on room air from 92% to 96% (p=0.000001) and inspiratory capacity (IC) from 750 mL to 1200 mL (p=0.000002) was observed. The number of patients with IC of 1200-1500 mL increased 3-fold, and those with an IC over 1500 mL increased 2.6-fold. The proportion of patients with low oxygenation (SpO2 less than 92%) decreased 5-fold after the procedure (p=0.0011). Good tolerability and no side effects of the procedure were noted in all patients. Impaired sputum expectoration early after cardiac surgery is observed in most patients and may cause low oxygenation. The main effects of the cough stimulation device were improvement of sputum expectoration and an increase in oxygenation. An increase in blood oxygen saturation and inspiratory capacity after a single procedure with this device was demonstrated. It resulted in a significantly decreased proportion of patients with respiratory insufficiency. No adverse effects of the procedure were observed.