The effect of incentive spirometry on postoperative pulmonary complications: a systematic review.

OBJECTIVE: To systematically review the evidence examining the use of incentive spirometry (IS) for the prevention of postoperative pulmonary complications (PPCs). METHODS: We searched MEDLINE, CINAHL, HealthSTAR, and Current Contents databases from their inception until June 2000. Key terms included "incentive spirometry," "breathing exercises," "chest physical therapy," and "pulmonary complications." Articles were limited to human studies in English. A secondary search of the reference lists of all identified articles also was conducted. A critical appraisal form was developed to extract and assess information. Each study was reviewed independently by one of three pairs of group members. The pair then met to reach consensus before presenting the report to the entire review group for final agreement. RESULTS: The search yielded 85 articles. Studies dealing with the use of IS for preventing PPCs (n = 46) were accepted for systematic review. In 35 of these studies, we were unable to accept the stated conclusions due to flaws in methodology. Critical appraisal of the 11 remaining studies indicated 10 studies in which there was no positive short-term effect or treatment effect of IS following cardiac or abdominal surgery. The only supportive study reported that IS, deep breathing, and intermittent positive-pressure breathing were equally more effective than no treatment in preventing PPCs following abdominal surgery. CONCLUSIONS: Presently, the evidence does not support the use of IS for decreasing the incidence of PPCs following cardiac or upper abdominal surgery.

Reliability of the six-minute walk test in people with fibromyalgia.

OBJECTIVE: To determine the test-retest reliability of the 6-minute walk test in people with fibromyalgia. METHODS: Twenty-six subjects (27-59 years of age) performed 3 walk tests over consecutive days before and after a 4-week treatment program. Reliability was determined using a one-way repeated measures analysis of variance and the intraclass correlation coefficient (ICC2,1). RESULTS: Reliability of the 6-minute walk test was excellent both at program intake (ICC2,1 = 0.91) and program completion (ICC2,1 = 0.98). On program intake, significant differences (P < 0.01) were found between test 1 (478 +/- 61 m) and test 2 (492 +/- 57 m), and between test 1 and test 3 (495 +/- 60 m). On program completion, there were no significant differences across the 3 replicate tests (507 m, 505 m, and 509 m). CONCLUSIONS: The 6-minute walk test is a reliable measure in people with fibromyalgia. In this study, two trials were required to achieve a stable walk performance before a treatment program. This learning effect was not present following the intervention.

Body position and cardiac dynamic and chronotropic responses to steady-state isocapnic hypoxaemia in humans.

Neural mediation of the human cardiac response to isocapnic (IC) steady-state hypoxaemia was investigated using coarse-graining spectral analysis of heart rate variability (HRV). Six young adults were exposed in random order to a hypoxia or control protocol, in supine and sitting postures, while end-tidal PCO2 (PET,CO2) was clamped at resting eucapnic levels. An initial 11 min period of euoxia (PET,O2 100 mmHg; 13.3 kPa) was followed by a 22 min exposure to hypoxia (PET,O2 55 mmHg; 7.3 kPa), or continued euoxia (control). Harmonic and fractal powers of HRV were determined for the terminal 400 heart beats in each time period. Ventilation was stimulated (P < 0.05) and cardiac dynamics altered only by exposure to hypoxia. The cardiac interpulse interval was shortened (P < 0.001) similarly during hypoxia in both body positions. Vagally mediated high-frequency harmonic power (Ph) of HRV was decreased by hypoxia only in the supine position, while the fractal dimension, also linked to cardiac vagal control, was decreased in the sitting position (P < 0.05). However, low-frequency harmonic power (Pl) and the HRV indicator of sympathetic activity (Pl/Ph) were not altered by hypoxia in either position. These results suggest that, in humans, tachycardia induced by moderate IC hypoxaemia (arterial O2 saturation Sa,O2 85 %) was mediated by vagal withdrawal, irrespective of body position and resting autonomic balance, while associated changes in HRV were positionally dependent.

Effect of TENS on pain, medications, and pulmonary function following coronary artery bypass graft surgery.

The efficacy of transcutaneous electrical nerve stimulation (TENS) as an adjunct to narcotic medications for the management of postoperative pain was assessed in a prospective, randomized, controlled study of patients following coronary artery bypass graft (CABG) surgery with the right or left internal thoracic artery (ITA). Forty-five male patients (mean age, 57 +/- 6 years) were randomly assigned to (1) TENS, (2) placebo TENS, or (3) control treatments (n = 15 each), following extubation and during the 24- to 72-h postoperative period. Two-way analysis of variance tests indicated no significant differences among treatment groups for (1) pain with cough, (2) narcotic medication intake, (3) FVC, (4) FEV1, and (5) PEFR (p > 0.05). However, pain at rest reported by the TENS group was significantly lower than that reported by the control group (treatment main effect; p < 0.04), although no significant differences were observed between the TENS and placebo or between the placebo and control groups (p > 0.05). All six criterion measures were characterized by significant changes over time for the entire group (n = 45; time main effect; p < 0.01), as follows: pain and medication intake were similar on days 1 and 2, but were significantly less on day 3, and pulmonary functions were significantly lower than preoperatively on day 1, decreased further on day 2, and despite an improvement on day 3, remained significantly lower than preoperative values (p < 0.01). This study suggests that the addition of TENS, applied continuously during the immediate postoperative period following CABG with ITA, may not be advantageous in pain management or the prevention of pulmonary dysfunction.

Pronounced increase in defibrillation threshold associated with pacing-induced cardiomyopathy in the dog.

Progressive changes in myopathology after implantation of an automatic defibrillator could compromise device efficacy. The influence of heart failure development on the defibrillation threshold was evaluated by means of a rapid ventricular pacing model of heart failure in dogs. After transvenous pacemaker lead implantation, adult mongrel dogs were randomly assigned to either the control (n = 7) or rapidly paced group (240 beats/min, n = 6). Seventeen days after implantation, triplicate determinations of the defibrillation threshold were made with three epicardial electrodes. The average defibrillation threshold was four times higher in the rapidly paced group, 13.3 +/- 2.0 joules (mean +/- SEM), than in the control group, 3.3 +/- 0.7 joules (p < 0.01), and was significantly correlated with ventricular weight (r = 0.70, p < 0.01). Both defibrillation threshold energy per gram of ventricle and ventricular weight corrected for body weight were significantly higher in rapidly paced dogs compared with control dogs. It was concluded that myocardial hypertrophy and heart failure may profoundly increase defibrillation energy requirements.

Effects of defibrillation shocks delivered directly over a major coronary artery.

This study investigated the influence of defibrillator shocks delivered directly over a coronary artery, independent of ventricular fibrillation, on cardiac hemodynamics. Thirty-six open chest, halothane anesthetized pigs were randomized to receive six shocks at one of 5.0, 7.5, or 10.0 joules (J). Shocks were delivered between two mesh electrodes (Medtronic TX-7) sutured onto the epicardium, one over the left anterior descending coronary artery and the second directly opposite on the posterobasal ventricular surface. Shock delivery was synchronized to the R wave of the cardiac cycle, to reduce the risk of inducing fibrillation, with a 5-minute stabilization period between successive shocks. Pressure from the left ventricle, the left anterior descending coronary artery, distal to the mesh electrode and the left circumflex (control) artery and contractility in the regions perfused by both arteries were measured. The shocks invariably produced an immediate (2-second postshock), but transient, depression in systolic pressure of the same magnitude for the left anterior descending coronary artery, circumflex artery and the left ventricle that recovered by 5-minute postshock. There was no dose dependent relationship to energy. Also there was no clear difference in myocardial wall motion between the area perfused by the left anterior descending coronary artery and that perfused by the circumflex artery. These results suggest that shocks up to 10 J delivered over an epicardial artery do not cause arterial spasm and do not compromise coronary artery blood flow.

Changes in centre of pressure of ground reaction forces prior to rapid arm movement in normal subjects and patients with cerebellar ataxia.

This study was designed to investigate the biomechanics of anticipatory postural responses. In particular the aim was to determine whether the centre of pressure of ground reaction forces moves in anticipation of an expected upper limb movement, and if so to determine the pattern (s) of centre of pressure change in normal subjects, and patients with cerebellar ataxia. Twenty-eight healthy, normal subjects (aged 30-64 years) and ten cerebellar ataxic patients (aged 30-80 years) each stood with feet parallel and 6 cm apart on a force platform. The subjects elevated their right arm to the horizontal as quickly as possible in response to a visual stimulus. The centre of pressure of ground reaction forces was recorded for 1 s: 600 ms before and 400 ms after initiation of arm movement. In 96% of normal subjects there were consistent patterns of change in the location of centre of pressure prior to the beginning of the rapid self-initiated arm movement. In 79% of subjects, there was a posterior shift of centre of pressure prior to arm movement. Ninety-six per cent of subjects exhibited a preparatory shift in centre of pressure in the lateral direction, most frequently to the left (75%). These patterns were repeatable both within and between subjects. There was a bimodal distribution in the onset time of the preparatory centre of pressure excursions, with initiation occurring at ⩽ 150 ms and ⩾ 300 ms prior to arm acceleration. Cerebellar ataxic subjects exhibited marked between-subject and within-subject variability in the patterns of centre of pressure excursion, including absence of preparatory excursions (in three subjects).