Respiratory Effects of a Single Dive to 50 Meters in Sport Divers with Asymptomatic Respiratory Atopy

Abstract

Increasing popularity of sports diving makes it likely that subjects with allergic respiratory diseases will be involved in diving with self contained underwater breathing apparatus (scuba). The present study evaluated the effects of a single scuba-dive on pulmonary function in subjects with respiratory atopy. Specific airways conductance (sGaw), residual volume (RV), forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), mid expiratory flow at 50% of FVC (MEF50), and transfer factor for carbon monoxide (TLCO) were measured in 9 sport divers with a history of hay fever and 9 matched healthy sport divers (control) before, 3 hours and 24 hours after a wet hyperbaric chamber dive to a depth of 50 m. Airway hyperresponsiveness (AHR) was assessed by methacholine challenge 4 weeks after the dive. Atopic subjects and controls did not differ with respect to anthropometric data, diving experience, and predive lung function. A 3% reduction in FVC was found 24h after the dive (p < 0.05) in both groups, whereas sGaw decreased by 15% 24 h after the dive (p < 0.05) in the subjects with respiratory atopy only. Postdive changes in RV, FEV1, MEF50, and TLCO did not reach level of statistical significance. AHR was obtained in 8/9 subjects with respiratory atopy. We conclude that subjects with atopic sensitization and asymptomatic AHR may be more susceptible to effects of diving on pulmonary function.

Short- and long-term effects of diving on pulmonary function

“…After exercise, there was a significant deterioration of FEV1 and forced expiratory flow at 25-75% of FVC in the asthmatic subjects compared to both the post-exercise dry control condition and healthy control subjects [77]. In a study comparing changes in pulmonary function after a simulated wet chamber dive to 50 m between nine subjects with hay fever and nine healthy controls there were slight reductions in FVC 24 h after the dive and a reduction in specific airway conductance in the atopic subjects only [78], which was interpreted as an increased susceptibility of atopic subjects to diving exposure. Another study investigated pulmonary function in 15 atopic nonasthmatic subjects and 15 healthy controls after dry chamber dives to simulated 50 m depth and wet dives to 50 m in seawater [79].…”

A Review of Asthma and Scuba Diving

“…One study revealed pronounced but minor lung function changes after a deep dive to 50 msw in a small group of asymptomatic scuba divers with airway hyperresponsiveness as assessed by methacholine challenge. [49] ASTHMA AS A CONSEQUENCE OF SCUBA DIVING?…”

“…[47] Occasionally, airway hyperresponsiveness has been reported to be present in single experienced divers elsewhere. [48,49] Thus, among selected samples of scuba divers there are a larger number of asymptomatic divers with airway hyperresponsiveness who had dived uneventfully for years. There are as yet no data indicating an increased risk of divingrelated injury in asymptomatic subjects with airway hyperresponsiveness.…”

Prevalence and characteristics of lung function changes in recreational scuba divers

“…They also demonstrated that effects on respiratory function were consistent with small airways dysfunction which may lead to long-term effects on respiratory function in SCUBA divers. 2 Cross-sectional studies have shown that divers frequently have unusually large lung volumes associated with a low forced expiratory volume in one second (FEV 1) / forced vital capacity (FVC) ratio (FEV 1%) suggestive of obstructive airways disease or airflow limitation. 3 Reduced airflow may be due to air trapping, which increases the risk of pulmonary barotrauma and arterial gas embolism during ascent.…”

“…2 The dive profile was controlled and subjects used full-face masks rather than demand valves. The study concluded that atopic divers are more susceptible to the effects of diving on lung function and suggested that divingrelated factors and diving history are associated with diminished flows in lung volumes.…”