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Sleep-disordered breathing improves in the first 6-9 weeks following stroke, but remains highly prevalent. Worse sleep-disordered breathing was observed following lacunar stroke, and in older subjects or those with pre-stroke handicap.

The obstructive sleep apnoea syndrome (OSAS) was first identified only 40 years ago and its clinical importance is increasingly recognized. Although now acknowledged as a worldwide problem, which in Western countries affects 2-4% of middle-aged men and 1-2% of middle-aged women, the majority of affected individuals remain undiagnosed. OSAS is strongly associated with obesity but is also increasingly identified in the less obese, in whom a particular craniofacial structure is an important contributory factor. The prevalence of OSAS is likely to be increasing in parallel with the epidemic of obesity currently occurring in many countries. The common presenting complaints are excessive daytime sleepiness and loud snoring. The sleepiness impairs social functioning, work performance and driving ability, and accounts for a large socio-economic burden on the community. Hypertension is an important independent association. The treatment of choice is nocturnal continuous positive airway pressure which is highly effective and is also cost effective.

P Pu ul lm mo on na ar ry y h hy yp pe er ri in nf fl la at ti io on n a a c cl li in ni ic ca al l o ov ve er rv vi ie ew w G.J. GibsonPulmonary hyperinflation a clinical overview. G.J. Gibson. ERS Journals Ltd 1996. ABSTRACT: Pulmonary hyperinflation is usually defined as an abnormal increase in functional residual capacity, i.e. lung volume at the end of tidal expiration. As such, it is virtually universal in patients with symptomatic diffuse airway obstruction. Hyperinflation inferred from a standard chest radiograph implies an increase in total lung capacity.The relaxation volume of the respiratory system (Vr) increases in patients with chronic airway disease as a result of changes in the elastic properties of the lungs and chest wall. In addition, a variable degree of dynamic hyperinflation may be present. This results from the onset of inspiration before lung volume has fallen to Vr. Dynamic hyperinflation is frequently present at rest in patients with moderate-to-severe airway obstruction, and it increases further on exercise, thereby increasing the mechanical load on the inspiratory muscles and at the same time reducing their mechanical advantage.Important clinical consequences and associations of hyperinflation include: distortions of chest wall motion; impaired inspiratory muscle function; increased oxygen cost of breathing; greater likelihood of hypercapnia; impaired exercise performance; and greater severity of breathlessness. The symptomatic improvement after treatment with a bronchodilator may be due, in part, to lessening of hyperinflation.

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Respiratory parameters in 29 normal older subjects (mean age-73 years, SD = 5.7) were studied at rest, during single water swallows, and in continuous drinking. Respiration was recorded by intranasal air pressure changes and the moment of swallowing by pharyngoesophageal manometry. Compared with respiration at rest, respiratory rate increased immediately after 5 mL swallows as duration of breath cycles decreased from a mean of 3.8 s at rest to 3.5 s after swallowing (p = 0.003), but regularity of respiration was maintained. Deglutition apnea showed a trend toward increasing duration from a median of 1.06 to 1.24 s (p = 0.096) as bolus volume increased from 5 to 20 mL. Oxygen saturation levels were also compared, with a median fall of 2% during swallowing, but with larger and unexplained falls in several subjects. Direction of airflow monitoring showed 91% of single 5 mL swallows were followed by expiration, with postswallow inspiratory breaths occurring in 41% of subjects. Continuous swallowing of 100 mL of water from a cup and straw was typically performed with a pattern of multiple swallows per breath, with expiration occurring after 78.5% (cup) and 63.5% (straw) of swallows. This definition of swallowing-induced respiratory changes in normal older people forms a valuable basis for future comparison with elderly dysphagic patients.

Twenty eight patients with bronchial carcinoma were studied before pneumonectomy. Measurement of spirometric indices, static lung volumes, transfer factor (TLCO), and transfer coefficient (Kco) was undertaken before and four months after pneumonectomy. Fourteen of the patients also performed a symptom limited progressive exercise test on a cycle ergometer before and four months after pneumonectomy. All patients had standard xenon-133 ventilation and technetium-99m perfusion scans performed before operation. Eleven patients had krypton-81m ventilation scans in addition. Significant correlations were seen between changes in FEV1, TLCO and Kco and the preoperative function of the resected lung as determined by percentage preoperative perfusion to that lung (p < 0.001). There were mean decreases in FEV, of 22% and in vital capacity (VC) of 28-7% predicted. Estimation of postoperative FEV, from the preoperative values showed equally good agreement with measured postoperative values whether 99mTc perfusion or 8"mKr ventilation scans were used in the 11 patients in whom both scans were available. Significant correlations were seen between change in maximum exercise ventilation (VEmax) or maximum oxygen uptake (Vo2max) after pneumonectomy and percentage preoperative perfusion to the resected lung (p < 0O001). Estimation of postoperative maximum ventilation and maximum oxygen uptake from the postoperative values on the basis of 99mTc perfusion scans showed good agreement with observed values. Perfusion scans are useful in estimating not only the changes in spirometric indices that follow pneumonectomy for bronchial carcinoma but also changes in carbon monoxide transfer and exercise capacity.

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