The Effect of Change in Posture on Spirometry in Patients with Obstructive Sleep Apnoea Syndrome.

OBJECTIVES: Obstructive sleep apnoea syndrome (OSAS) is a growing health concern as it is associated with serious comorbidities. OSAS is mainly related to obesity, age, gender and a narrowed upper airway is commonly seen in patients with OSAS. This study aimed to compare spirometry parameters between obese OSAS patients and non-obese OSAS patients when patients moved from sitting to supine. METHODS: This cross-sectional study was conducted at Sultan Qaboos University Hospital, Muscat, Oman, between December 2009 and December 2010. Patients with severe OSAS and who were OSAS treatment naïve were recruited. Spirometry was performed in all patients in sitting and supine positions to assess forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1/FVC, forced expiratory flow (FEF) 50%, FEF 25-75%, maximum forced inspiratory flow and expiratory reserve volume. The mean difference in spirometry parameters between patients in sitting and supine positions was calculated. RESULTS: A total of 27 OSAS patients (19 males and 8 females) were included in this study. There was a significant difference in FEV1/FVC in obese and non-obese patients when changing position (P = 0.03). In addition, there was a significant change between male and female patients' FVC percentages (P <0.05). Male patients with OSAS had reduced FVC compared to females. There was no significant difference in the remaining spirometry parameters with patients' change of position. CONCLUSION: A supine position may cause lower airway obstruction in obese patients with OSAS. The reduced FVC in males possibly contributes to the high prevalence of OSAS in men compared to women.

Effects of pranayam breathing on respiratory pressures and sympathovagal balance of patients with chronic airflow limitation and in control subjects.

OBJECTIVES: The objective of this study was to compare the effects of Pranayam breathing on respiratory muscle strength measured as maximum expiratory and inspiratory pressures (MEP and MIP) and relevant spirometry parameters in patients with chronic obstructive pulmonary disease (COPD) and in control subjects, and on the sympatho-vagal balance in both the groups. METHODS: The research was performed in the Clinical Physiology Department, Sultan Qaboos University Hospital, Oman. Eleven patients (mean age 43.91 ± 20.56 yr; mean BMI 21.9 ± 5.5 kg/m(2)) and 6 controls (43.5 ± 14.6yr; 25.4 ± 3.2 kg/m(2)) learnt and practised Pranayam. Their respiratory and cardiovascular parameters were recorded. Their respiratory "well being" was noted as a visual analogue score (VAS). The respiratory parameters were expressed as a percentage change of predicted values. RESULTS: Patients' respiratory parameters were significantly lower than those of controls. Patients' maximum respiratory pressures did not improve after Pranayam; however, they showed significant improvement in VAS 5.4 ± 2.4 to 7.2 ± 1.2 (P < 0.03). Controls showed significant increase in MIP after Pranayam exercises. There were no changes in other spirometry indices. Controls showed significant increase in their systolic blood pressure and stroke index after exercise. The vago-sympathetic balance shifted towards sympathetic in both patients and controls after exercise. CONCLUSION: The improvement in MIP in controls indicated the positive effect of Pranayam exercise; however, it may not be an adequately stressful exercise to produce changes in the respiratory parameters of COPD patients. The increase in VAS in patients suggested improvement in respiratory distress and quality of life.

To Err is Human Case Reports of Two Military Aircraft Accidents: Possible mechanisms of human failure.

It has been postulated that pilot error or in-flight incapacitation may be the main contributory factors to 70-80% of aircraft accidents. Two fatal aircraft accidents are presented in which either of the above possibilities may have played a role. The first case report describes an erroneous decision by a fighter pilot to use a seat position adjustment of the ejection seat leading to fatal injuries when he had to eject from his aircraft. Injuries to the body of the pilot, and observations on the state of his flying clothing and the ejection seat were used to postulate the mechanism of fatal injury and establish the cause of the accident. The second case report describes the sequence of events which culminated in the incapacitation of a fighter pilot while executing a routine manouevre. This resulted in a fatal air crash. Possible contributions of environmental factors which may have resulted in failure of his physiological mechanisms are discussed.