Koehle
SCUBA breathing decreased diffusing capacity following a shallow immersion dive, but not when using SCUBA out of the water.
| Clinical Bottom Line: 1. Breathing through SCUBA underwater reduced diffusing capacity, but breathing through SCUBA on the surface did not. |
Citation/s: 1. Koehle MS, Hodges ANH,LynnBM, Rachich MF, McKenzie DC. Diffusing capacity and spirometry following a dive to 4.5 meters. Undersea and Hyperbaric Medicine 2006; 33(2):109-118.
Three-part Clinical Question: For SCUBA divers, does the use of the SCUBA itself, compared to the use of SCUBA while immersed, result in any changes in pulmonary function? Search Terms: Diving, diffusing capacity, spirometry
The Study:Non-blinded randomised cross-over trial with intention-to-treat. The Study Patients: Healthy SCUBA divers with no history of respiratory disease. Control group (N = 10; 10 analysed): A 60 minute period of breathing through SCUBA at 1 ATA while non-immersed. Two separate iterations at least 48 hours apart. Experimental group (N = 10; 10 analysed): A 60 minute period of breathing through SCUBA whilst immersed at 4.5 metres in a swimming pool.
The Evidence:
| Measure | Pre-exposure | Post-exposure | Difference at 90 minutes | 95% CI | ||
| ^ | Mean | SD | Mean | SD | ^ | ^ |
| Diffusing capacity for CO in controls (mmol/min/kPa) | 8.65 | 2.48 | 8.64 | 2.45 | 0.010 | -2.31 to 2.33 |
| Diffusing capacity for CO in immersed group (mmol/min/kPa) | 8.96 | 2.35 | 7.68 | 2.48 | 1.280 | -0.99 to 3.55 |
Comments: 1. Measured changes were greater at 90 minutes than 60 minutes. 2. The authors' more sophisticated statistics showed a significant reduction where our simple t-test does not. 3. There were no significant changes in any spirometry measurements. 4. The observed changes seem to imply that alterations in diffusing capacity may not be depth related, but rather, immersion related.
Appraised by: Mike Bennett, Sydney ; Tuesday, 26 June 2007Email: [| m.bennett@unsw.edu.au] Kill or Update By: December 2021
