Summary
This is a second broadcast of Professor Denny Levett's EBPOM conference presentation on preoperative inspiratory muscle training (IMT). She walks through the epidemiology of post-operative pulmonary complications, explaining they affect 5-40% of surgical patients and are more common than cardiac complications. IMT trains the diaphragm and intercostal muscles using handheld resistance devices, with 30 breaths twice daily being the standard protocol. Levett reviews the evidence base including a Cochrane review showing 50% reduction in pulmonary complications and discusses the critical role of supervision in achieving results. She introduces the INSPIRE trial, a major NHS-funded 2,500-patient RCT designed to test IMT effectiveness in real clinical practice with IMT, sham, and usual care arms across multiple UK centers.
Key Points
- Pulmonary complications after surgery are 2-3x more common than cardiac complications
- IMT trains respiratory muscles through resistance breathing with a handheld device
- Standard protocol is 30 breaths twice daily at above 30% of maximum inspiratory pressure
- Systematic reviews consistently show approximately 50% reduction in post-op pulmonary complications
- Two weeks is the minimum effective training duration, with plateau at 8-12 weeks
- Without supervision, IMT shows no benefit -- patients need at least initial follow-up within 3-5 days
- IMT differs from incentive spirometry, which has no evidence of effectiveness
- The INSPIRE trial will recruit 2,500 patients across UK hospitals to test real-world implementation
Key Moments
Pulmonary complications are more common than cardiac after surgery
Professor Levett highlights that post-operative pulmonary complications are actually more common than cardiac complications, causing over 1 million complications annually in the US with nearly 5 million additional hospital days.
"In fact, pulmonary complications, although we focus a huge amount on cardiac complications, are more common than cardiac complications in the post-operative period."
Electronic IMT devices provide more training per breath than mechanical
Newer electronic IMT devices reduce load toward the end of each breath, accounting for the natural weakening of muscles at full inspiration. This means patients complete full breaths and get more training stimulus per breath compared to fixed mechanical devices.
"Where these new electronic devices, the load declines towards the end of the breath. And what's the net result of that? Why does that matter? It essentially means for each breath you get more training."
Two weeks of IMT is enough to reduce post-op complications before cancer surgery
Subgroup analysis shows that even training for less than 14 days produces similar risk reduction to longer programs, making IMT practical for tight surgical timelines like cancer surgery pathways.
"Quite reassuringly, in fact, more than 14 days to less than 14 days, there's very little difference, suggesting that you can get very significant effect within two weeks, which is excellent for our tight clinical pathways, so for example, before cancer surgery."
