Cardiovascular responses to manual hyperinflation in post-operative coronary artery surgery patients

Abstract

The aims of this study were to investigate the acute cardiovascular response to manual hyperinflation and to determine whether the technique results in haemodynamic compromise in coronary artery surgery subjects in the early post-operative period. A repeated-measures clinical trial involving a single intervention period was conducted. Manual hyperinflation using a two-litre resuscitation circuit was delivered within 5 h of surgery by experienced physiotherapists for a period of 4 min to subjects (n = 30) who had undergone coronary artery surgery. Swan-Ganz catheters and bedside monitoring showed significant changes in heart rate, mean pulmonary artery pressure, central venous pressure and the pulmonary vascular resistance index measured during, or after, manual hyperinflation. These changes in mean pulmonary arterial pressure and central venous pressure may be due to alterations in intrathoracic pressures generated during manual hyperinflation; however, the changes in heart rate and the pulmonary vascular resistance index are not readily explained. We conclude that the use of manual hyperinflation as part of the immediate post-operative physiotherapy management of stable, mechanically ventilated coronary artery surgery patients does produce significant changes in some haemodynamic parameters, but none of the recorded changes were of a magnitude considered to be clinically significant.

Benefits and risks of manual hyperinflation in intubated and mechanically ventilated intensive care unit patients: a systematic review

“…We included 13 interventional studies (six randomized controlled trials of MH [5,20-24], two randomized crossover trials comparing MH with endotracheal suctioning [25,26], four randomized crossover trials comparing MH with hyperinflation by the mechanical ventilator [27-30], and one randomized crossover trial comparing two different manual-ventilation bags [31]), and six observational studies [7,8,32-35]. Physiological end points were respiratory mechanics [20-22,25,27-31], arterial oxygenation [5,20-24,26-28,30,31], and clearance of airway secretions [5,26,27,29-31].…”

“…Clinical end points included duration of mechanical ventilation [21,23], length of stay [21,23], and incidence of pneumonia [23]. Reported side effects included effects on heart rate and systemic blood pressure [7,8,20,26,32-34], cardiac output [7,8,32,33,35], and pulmonary artery pressures and central venous pressures [32,33,35]. …”

Manual hyperinflation causes norepinephrine release

“…43 Further work is planned to compare the hemodynamic and respiratory effects of various FiO 2 levels. Previous studies 17 have applied MHI with an FiO 2 Ͻ 1.0 with no detrimental effect on gas exchange.…”

“…Patient selection and treatment parameters in some studies 14 did not conform to accepted guidelines for MHI. 4 More recent studies 10,17,18 that have controlled PIP and inclusion criteria have demonstrated minimal hemodynamic effects. We recently completed a study 10 standardizing PIP, PEEP, and I:E ratio during MHI with minimal changes in hemodynamics.…”

“…13 This makes it difficult to establish the risk-to-benefit of using this technique in critically ill patients. There have been a range of effects in previous studies on hemodynamics 10,[14][15][16][17][18] ; however, a variety of personnel, peak inspiratory pressures (PIPs), positive end-expiratory pressures (PEEPs), and V T s were employed. Patient selection and treatment parameters in some studies 14 did not conform to accepted guidelines for MHI.…”