SUMMARY1. The change in ventilation at the start of exercise was determined during both hyperoxic rebreathing and air breathing in four volunteers.2. In order to differentiate between the effects of limb-movement frequency and exercise load in terms of oxygen uptake, three treadmill exercises were tested: El, at an oxygen uptake of 1 1/min on a level treadmill; E2, at 2 1/min on an inclined treadmill at the same speed as El; E3, at 2 1/min on a level treadmill at a higher speed. All of the exercises were performed at a walking pace. 3. Prior to rebreathing, hyperventilation for 5 min to 20 mmHg was used to reduce carbon dioxide to below the central chemoreceptor threshold. From eleven to fourteen rebreathing experiments were done on each volunteer for each of the three exercises, with the treadmill started at carbon dioxide levels which ranged from 36 (below threshold) to 58 mmHg (above threshold).4. Ten experiments were performed on each volunteer for each of the three exercises during air breathing, with the treadmill started after 5 min of rest.5. In both the rebreathing experiments and the air breathing experiments it was found that the change in ventilation at the start of exercise was the same for exercises El and E2, and significantly greater for exercise E3.6. It was concluded that the frequency of limb movement, rather than exercise load (oxygen consumption) is a determinant of the change in ventilation at the start of exercise.

These experiments examined the changes in ventilation during a 40-s ramp increase in exercise load, produced by increasing either the speed of the treadmill or the grade, to equivalent end-points of oxygen uptake. Six subjects underwent five trials each for grade and speed, while ventilation was monitored breath-by-breath. For each subject, ventilation versus time for all five of the speed trials was plotted on a single graph and fitted by linear regression. The data for the grade trials were similarly treated. For all subjects, the slope of the regression line for the speed plots was found to be significantly (P < 0.05) greater than that for the grade plots. We concluded that these experimental results support the hypothesis that the neural drive to ventilation persists as exercise continues and is proportionately related to the frequency of limb movement.

OBJECTIVE: To provide physicians, physiotherapists, nurses and respiratory therapists with guidelines for the application of airway suctioning. DESIGN: This clinical practice guideline was developed using the model by Browman and colleagues. A working group of representatives from four professional colleges (nurses, physicians and surgeons, physiotherapists and respiratory therapists) and research experts was formed to conduct a systematic review, develop evidence-based recommendations and generate clinical practice guidelines. MEDLINE (1966 to 1998), CINAHL (1982) and EMBASE (1974 as well as the reference lists of identified articles were searched. Inclusion of articles was determined by at least two group members, and studies were classified according to type. Randomized, controlled; randomized; and nonrandomized crossover and comparative cohort trials were grouped by type of intervention and population for use in the development of recommendations. Other observational and animal studies dealing with adverse effects of suctioning were included in the review but were not used in the development of recommendations. Input on the evidencebased recommendations was sought and incorporated from members of all four professions and from experts on content and methodology. SETTING: Any setting (hospital or home) where suctioning is performed. POPULATION: Intubated and nonintubated adults, infants and children. RESULTS AND CONCLUSIONS: An attempt was made to develop recommendations in each of the subcategories of suctioning techniques addressed by at least one study. In some subcategories, definite recommendations were made (13 in adults, and three in children and infants); in other subcategories, insufficient evidence precluded recommendations. The recommendations addressed the following aspects of suctioning: preoxygenation, hyperinflation, insufflation, hyperoxygenation, hyperventilation, saline instillation, adaptor use, medication use, open and closed systems, and various types of catheters.

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The authors concluded that the evidence was sparse, weak and difficult to interpret. The authors' conclusions reflect the paucity of the evidence presented but the implications for practice may be overstated due to the quality and quantity of the underlying evidence. Authors' objectives To evaluate the evidence for cardiorespiratory physical therapy techniques in the management of patients with acute medical conditions. Searching MEDLINE and CINAHL were searched to February 2002 and EMBASE was searched to August 2002; search terms were reported. The Cochrane Library was searched (dates not reported). Searches were limited to articles in English. Reference lists of identified studies were checked. Study selection Randomised controlled trials (RCTs) of cardiorespiratory physical therapy interventions for adult in-patients with acute medical conditions were eligible for inclusion. RCTs with a crossover design were included. Studies with significant methodological and/or statistical problems and studies of postsurgical patients were excluded. Cardiorespiratory physical therapy interventions included postural drainage, coughing, huffing, percussion, vibration, positioning, turning and hyperinflation. Studies evaluated physical therapy in a range of acute conditions (atelectasis, pneumonia, pneumothorax, pleural effusion, deep vein thrombosis, acute myocardial infarction and mechanically ventilated patients). Measured outcomes included pulmonary and cardiorespiratory measures, mortality and length of hospital stay. Titles and abstracts were assessed by at least two reviewers; results from the Cochrane Library search were assessed by one reviewer. Assessment of study quality Two reviewers independently assessed study quality using the Jadad scale of randomisation, blinding and withdrawals. Generally, the maximum Jadad score is 5 (indicating higher quality). Disagreements were resolved by consensus. Data extraction Two reviewers were involved in data extraction, which focused on directions of effect, statistical significance of differences and p-values. Methods of synthesis A narrative synthesis was presented. Studies were grouped by patient population. Results of the review Twenty four RCTs were included (1,603 patients); seven RCTs were a crossover design. Thirteen studies scored 3 on the Jadad scale (the best possible score owing to double-blinding often not being possible). Most of the included studies were small and all were underpowered. The evidence showed either mixed results or no differences between physiotherapy and control group outcomes in patients with atelectasis, pneumonia, pneumothorax, pleural effusion, deep vein thrombosis and acute myocardial infarction. One large study supported the use of prone positioning to improve oxygenation in patients with acute respiratory distress syndrome. One small crossover study found oxygenation was improved in mechanically ventilated