Typically, preoperative respiratory muscle training takes place over a period of weeks. Why did you choose to look at a much shorter regimen?

Most of the respiratory muscle training programs reported in clinical trials were two to four weeks long.

However, these trials were primarily in Western countries where preoperative respiratory muscle training takes place through pre-admission clinics, outpatient departments or home-based programs.

Such prehabilitation models have yet to be established in China; preoperative interventions, if deemed necessary, are undertaken after hospital admission.

Given these constraints and the associated cost implications, we designed this project to be a pragmatic feasibility study requiring patient admission three days before surgery.

Despite the shortened program, our findings demonstrated that three days of preoperative respiratory training improved both pulmonary reserves and recovery after open-heart surgery in our cohort.

We hope that the cost-saving implications of our evidence will support the case for establishing pre-admission clinics in China.

What other groups was the inspiratory muscle training group compared to?

The intensity of the training program varied between our three groups.

Our inspiratory muscle training (IMT) group trained at 30 per cent of maximal inspiratory pressure.

We compared this to a sham IMT group who trained at 10 per cent of maximal inspiratory pressure and a control group who received no IMT at all.

All groups received a standardised education session from a cardiac nurse.

How did the training affect patients as they were heading into the surgery?

Most studies report that preoperative training optimises post- surgical outcomes.

Our study provides evidence to show that preoperative respiratory muscle training actually raises the physiological reserves of a patient prior to surgery to combat the surgical stress response.

In comparison to the sham group, the IMT group showed improved forced vital capacity by 80 millilitres, forced expiratory volume in one second by 130 millilitres, maximal inspiratory pressure of 20 centimetres of water and maximum voluntary ventilation by 19 litres per minute on the day prior to surgery.

Our cohort’s ‘fit to fight’ status was therefore optimised.

Did these effects protect against pulmonary complications after surgery?

Definitely. The incidence of postoperative pulmonary complications was 60 per cent.

However, in the preoperative IMT group this incidence was only 43 per cent compared to 62 and 64 per cent in the sham and control groups.

The incidence of atelectasis was lowest in the IMT group, with an absolute risk difference of –0.27 and –0.20 when compared to the sham IMT and control groups respectively.

Were there any differences between the groups after being discharged from hospital?

Yes, the three-day preoperative respiratory training enhanced surgical recovery compared to both sham IMT and no training.

All lung function parameters in the three-day preoperative IMT group were higher than in the other two groups.

However, a decline in lung function after thoracic surgery is unavoidable due to the trauma of surgery, inflammatory response, post-anaesthesia effects, pain and lung micro-atelectasis.

On discharge from hospital—approximately seven days post-surgery—the maximal inspiratory pressure in the IMT group was only five centimetres of water below admission baseline, while the sham IMT and no training groups recorded around 30 centimetres of water below baseline.

The recovery of maximal voluntary ventilation at discharge showed comparable improvements, although these differences were less dramatic for forced expiratory volume in one second and forced vital capacity.

The decrease in these parameters was 60 millilitres and 180 millilitres less than the sham IMT and no training groups respectively.

What do you think research in this field should address next?

The evidence to support the cost-to-benefit ratio of prevention rather than managing complications post-surgery is overwhelming.

Dr Ianthe Boden and her group have provided strong evidence of the cost-effectiveness of preoperative physiotherapy interventions.

The next step should be to focus on identifying effective models of preoperative education delivery and intervention.

In Asian countries, researchers could explore the involvement of family and carers in the preoperative education of patients.

Support from the surgeon and family greatly enhances acceptance and compliance with preoperative and postoperative physiotherapy interventions.

>>Dr Alice Jones FACP is a Specialist Cardiorespiratory Physiotherapist (as awarded by the Australian College of Physiotherapists in 1995) and an honorary professor at the University of Queensland. She is also a visiting professor at the West China Hospital Sichuan University, Beijing Sport University, Kunming Medical University and Shanghai University of Traditional Chinese Medicine in China.