The influences of positive end expiratory pressure (PEEP) associated with physiotherapy intervention in phase I cardiac rehabilitation

Effectiveness of early cardiac rehabilitation in patients with heart valve surgery: a randomized, controlled trial

OBJECTIVE

Complications of heart valve surgery lead to physical inactivity and produce harmful effects. This study aimed to investigate the role of a cardiac rehabilitation program and its long-term effect in patients after heart valve surgery.

METHODS

We performed a single-blind, randomized, controlled trial. Patients with heart valve surgery were randomly assigned to receive early cardiac rehabilitation (intervention group, 44 patients) or the usual care (control group, 43 patients). The intervention group performed sitting, standing, and walking exercises, followed by endurance training. The control group received usual care and did not engage in any physical activity. Physical function was assessed by the Short Physical Performance Battery (SPPB) and other measurement tools.

RESULTS

The intervention group showed a significant beneficial effect regarding physical capacity as shown by the SPPB and the 6-minute walking test at hospital discharge, and a better long-term effect was achieved at 6 months compared with the control group. An improvement in physical function (e.g., the SPPB) after hospital discharge predicted follow-up mortality (odds ratio = 0.416, 95% confidence interval: 0.218-0.792).

CONCLUSION

Early cardiac rehabilitation appears to be an effective approach to improve the physical function and survival of patients with heart valve surgery.

Effect of Positive Expiratory Pressure Therapy on Lung Volumes and Health Outcomes in Adults With Chest Trauma: A Systematic Review and Meta-Analysis

OBJECTIVE

The purposes of this study were to evaluate the effect of positive expiratory pressure (PEP) therapy on lung volumes and health outcomes in adults with chest trauma and to investigate any adverse effects and optimal dosages leading to the greatest positive impact on lung volumes and recovery.

METHODS

Data sources were MEDLINE/PubMed, Embase, Cochrane Library, Physiotherapy Evidence Database, CINAHL, Open Access Thesis/Dissertations, EBSCO Open Dissertations, and OpenSIGLE/Open Grey. Randomized controlled trials investigating PEP therapy compared with usual care or other physical therapist interventions were included. Participants were >18 years old and who were admitted to the hospital with any form of chest trauma, including lung or cardiac surgery, blunt chest trauma, and rib fractures. Methodological quality was assessed using the Physiotherapy Evidence Database Scale, and the level of evidence was downgraded using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Eleven studies involving 661 participants met inclusion eligibility. There was very low-level evidence that PEP improved forced vital capacity (standardized mean difference = -0.50; 95% CI = -0.79 to -0.21), forced expiratory volume in 1 second (standardized mean difference = -0.38; 95% CI = -0.62 to -0.13), and reduced the incidence of pneumonia (relative risk = 0.16; 95% CI = 0.03 to 0.85). Respiratory muscle strength also significantly improved in all 3 studies reporting this outcome. There was very low-level evidence that PEP did not improve other lung function measures, arterial blood gases, atelectasis, or hospital length of stay. Both PEP devices and dosages varied among the studies, and no adverse events were reported.

CONCLUSION

PEP therapy is a safe intervention with very low-level evidence showing improvements in forced vital capacity, forced expiratory volume in 1 second, respiratory muscle strength, and incidence of pneumonia. It does not improve arterial blood gases, atelectasis, or hospital length of stay. Because the evidence is very low level, more rigorous physiological and dose-response studies are required to understand the true impact of PEP on the lungs after chest trauma.

IMPACT

There is currently no strong evidence for physical therapists to routinely use PEP devices following chest trauma. However, there is no evidence of adverse events; therefore, in specific clinical situations, PEP therapy may be considered.

Beneficial Effects of a Short Course of Physical Prehabilitation on Neurophysiological Functioning and Neurovascular Biomarkers in Patients Undergoing Coronary Artery Bypass Grafting

This study aimed to evaluate the effects of a short course of physical prehabilitation on neurophysiological functioning and markers of the neurovascular unit in patients undergoing coronary artery bypass grafting (CABG). We performed a prospective randomized study involving 97 male CABG patients aged 45–70 years, 47 of whom underwent a 5–7-day preoperative course of aerobic physical training (PhT). Both groups of patients were comparable with respect to baseline clinical and anamnestic characteristics. An extended neuropsychological and electroencephalographic (EEG) study was performed before surgery and at 7–10 days after CABG. Markers of the neurovascular unit [S100β, neuron-specific enolase (NSE), and brain-derived neurotrophic factor (BDNF)] were examined as metabolic correlations of early postoperative cognitive dysfunction (POCD) at three time points: before surgery, within the first 24 h after surgery, and 7–10 days after CABG. POCD developed in 58% of patients who underwent preoperative PhT, and in 79.5% of patients who did not undergo training, 7–10 days after CABG. Patients without prehabilitation demonstrated a higher percentage of theta1 power increase in the relative change values as compared to the PhT patients (p = 0.015). The short preoperative course of PhT was associated with low plasma S100β concentration, but high BDNF levels in the postoperative period. Patients who underwent a short preoperative course of PhT had better cognitive and electrical cortical activity indicators. Markers of the neurovascular unit indicated lower perioperative brain injury after CABG in those who underwent training. A short course of PhT before CABG can decrease the brain’s susceptibility to ischemia and reduce the severity of cognitive impairments in cardiac surgery patients. Electrical brain activity indicators and neurovascular markers, such as S100β and BDNF, can be informative for the effectiveness of cardiac rehabilitation programs.

Effect of continuous positive airway pressure associated to exercise on the breathing pattern and heart rate variability of patients undergoing coronary artery bypass grafting surgery: a randomized controlled trial

Continuous positive airway pressure (CPAP) has been used to improve gas exchange and diaphragmatic function, among others benefits. Moreover, it can be used to increase exercise tolerance and positively influence ventilatory function and breathing pattern (BP) during exercise. However, there is no information about the long-term effects of CPAP, as an adjunct to an inpatient cardiac rehabilitation (CR) program, on BP and heart rate variability (HRV) of patients after coronary artery bypass grafting surgery (CABG). Twenty patients were allocated to receive, after randomization, standard inpatient CR without CPAP (control group - CG) or CR with CPAP between 10 to 12 cmH₂O (CPAP group - CPG) associated with the exercises. Participants were assessed preoperatively and on the discharge day, in the sitting rest position. Outcome measurements included BP variables, collected by respiratory inductive plethysmography, and HRV, collected by polar precision performance. The CPG presented lower values of percent rib cage inspiratory and expiratory contributions to tidal volume (%RCi and %RCe) at discharge time, compared to CG. No statistical differences between groups were observed for HRV variables and both groups presented lower values of these indices, compared to preoperative ones. In this context, the patients who received CPAP throughout the whole rehabilitation program were discharged with a better BP, which could indicate more synchronized breathing. CPAP did not influence cardiac autonomic modulation in the long term.

Cardiovascular Physiotherapy on Respiratory Sinus Arrhythmia of Patients Undergoing Coronary Artery Bypass Grafting

Introduction: Patients in the postoperative period of coronary artery bypass grafting (CABG) present respiratory and autonomic dysfunctions. In this sense, cardiovascular physiotherapy has been offered as an indispensable differential for the improvement of the prognosis of this population. Heart rate variability is a simple, noninvasive method to analyze autonomic modulation, as well as the accentuation maneuver of respiratory sinus arrhythmia, which demonstrates the parasympathetic autonomic control over the heart. Five patients undergoing cardiac surgery performed a protocol of cardiovascular physiotherapy in the postoperative period and had their data referring to the preoperative period, the 1st and 4th postoperative days analyzed.

Positive expiratory pressure in postoperative cardiac patients in intensive care: A randomized controlled trial

OBJECTIVE

To evaluate effectiveness of positive expiratory pressure blow-bottle device compared to expiratory positive airway pressure and conventional physiotherapy on pulmonary function in postoperative cardiac surgery patients in intensive care unit.

DESIGN

A randomized controlled trial.

SETTINGS

Tertiary care.

SUBJECTS

48 patients (16 in each group; aged 64.5 ± 9.1 years, 38 male) submitted to cardiac surgery.

INTERVENTIONS

Patients were randomized into conventional physiotherapy (G1), positive expiratory pressure blow-bottle device (G2) or expiratory positive airway pressure, both associated with conventional physiotherapy (G3). G2 and G3 performed three sets of 10 repetitions in each session for each technique.

MAIN MEASURES

Pulmonary function (primary); respiratory muscle strength, radiological changes, pulmonary complications, length of intensive care unit and hospital stay (secondary) assessed preoperatively and on the 3rd postoperative day.

RESULTS

Pulmonary function (except for forced expiratory volume in one second/ forced vital capacity % predicted) and respiratory muscle strength showed significant reduction from the preoperative to the 3rd postoperative in all groups (P < 0.001), with no difference between groups (P > 0.05). Regarding radiological changes, length of intensive care unit stay and length of hospital stay, there was no significant difference between groups (P > 0.05).

CONCLUSION

Both positive expiratory pressure techniques associated with conventional physiotherapy were similar, but there was no difference regarding the use of positive expiratory pressure compared to conventional physiotherapy.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03639974.https://clinicaltrials.gov/ct2/show/NCT03639974.

Methodological Quality of Randomized Clinical Trials of Respiratory Physiotherapy in Coronary Artery Bypass Grafting Patients in the Intensive Care Unit: a Systematic Review

OBJECTIVE

To assess methodological quality of the randomized controlled trials of physiotherapy in patients undergoing coronary artery bypass grafting in the intensive care unit.

METHODS

The studies published until May 2015, in MEDLINE, Cochrane and PEDro were included. The primary outcome extracted was proper filling of the Cochrane Collaboration's tool's items and the secondary was suitability to the requirements of the CONSORT Statement and its extension.

RESULTS

From 807 studies identified, 39 were included. Most at CONSORT items showed a better adequacy after the statement's publication. Studies with positive outcomes presented better methodological quality.

CONCLUSION

The methodological quality of the studies has been improving over the years. However, many aspects can still be better designed.

Acute bag-valve breathing maneuvers plus manual chest compression is safe during stable septic shock: a randomized clinical trial

Objective

To evaluate the effects of bag-valve breathing maneuvers combined with standard manual chest compression techniques on safety, hemodynamics and oxygenation in stable septic shock patients.

Design

A parallel, assessor-blinded, randomized trial of two groups. A computer-generated list of random numbers was prepared by an independent researcher to allocate treatments.

Setting

The Intensive Care Unit at Hospital São Lucas, Pontifícia Universidade Católica do Rio Grande do Sul.

Participants

Fifty-two subjects were assessed for eligibility, and 32 were included. All included subjects (n = 32) received the allocated intervention (n = 19 for the Experimental Group and n = 13 for the Control Group).

Intervention

Twenty minutes of bag-valve breathing maneuvers combined with manual chest compression techniques (Experimental Group) or chest compression, as routinely used at our intensive care unit (Control Group). Follow-up was performed immediately after and at 30 minutes after the intervention.

Main outcome measure

Mean artery pressure.

Results

All included subjects completed the trial (N = 32). We found no relevant effects on mean artery pressure (p = 0.17), heart rate (p = 0.50) or mean pulmonary artery pressure (p = 0.89) after adjusting for subject age and weight. Both groups were identical regarding oxygen consumption after the data adjustment (p = 0.84). Peripheral oxygen saturation tended to increase over time in both groups (p = 0.05), and there was no significant association between cardiac output and venous oxygen saturation (p = 0.813). No clinical deterioration was observed.

Conclusion

A single session of bag-valve breathing maneuvers combined with manual chest compression is hemodynamically safe for stable septic-shocked subjects over the short-term.

Effectiveness of an early mobilization program on functional capacity after coronary artery bypass surgery: A randomized controlled trial protocol

Background:

Muscle atrophy and prolonged inactivity are associated with an increased sensation of fatigue and reduced functional capacity in the postoperative period in patients undergoing coronary artery bypass grafting. Cardiac rehabilitation after hospital discharge is highly recommended and contributes to improvement in functional capacity and quality of life. However, few studies have evaluated the effectiveness of early mobilization protocols during hospitalization on the patterns of physical activity and functional capacity after coronary artery bypass grafting.

Objective:

To investigate the effectiveness of an early mobilization program on the functional capacity of patients undergoing coronary artery bypass grafting in the short and long term.

Methods:

This is a prospective, randomized, controlled, single-blind trial protocol that will evaluate 66 consecutive patients undergoing coronary artery bypass grafting. Patients will be randomized into two training groups: the control group (N = 33), which will perform breathing exercises and the intervention group (N = 33), which will perform breathing exercises and aerobic exercises. The groups will receive treatment from first to the seventh postoperative day, twice daily. In the preoperative period, the following outcomes will be assessed: physical activity level (Baecke Questionnaire), Functional Independence Measure, and functional capacity (6-min walking test). Functional capacity will be reassessed after the 7th and 60th postoperative day. Pulmonary complications and length of hospital stay will also be evaluated. Statistical analysis will be calculated using linear mixed models and will be based on intention-to-treat. The level of significance will be set at α = 5%.

High-Intensity Inspiratory Protocol Increases Heart Rate Variability in Myocardial Revascularization Patients

Objective:

To evaluate heart rate variability during an inspiratory muscle endurance protocol at three different load levels [30%, 60% and 80% of maximal inspiratory pressure], in patients who had previously undergone coronary artery bypass grafting.

Methods:

Nineteen late postoperative myocardial revascularization patients participating in a cardiovascular rehabilitation program were studied. Maximal inspiratory pressure maneuvers were performed. An inspiratory muscle endurance protocol at 30%, 60% and 80% of maximal inspiratory pressure was applied for four minutes each, in random order. Heart rate and RR intervals were recorded and heart rate variability was analyzed by time (RMSSD-the mean of the standard deviations for all R-R intervals, and RMSM-root-mean square differences of successive R-R intervals) and frequency domains indices (high and low frequency) in normalized units. ANOVA for repeated measurements was used to compare heart rate variability indices and Student t-test was used to compare the maximal inspiratory pressure and maximal expiratory pressure values.

Results:

Heart rate increased during performance of maximal respiratory pressures maneuvers, and the maximal inspiratory pressure and maximal expiratory pressure mean values were significantly lower than predicted values (P<0.05). RMSSD increased significantly at 80% in relation to rest and 30% of maximal inspiratory pressure and RMSM decreased at 30% and 60% of maximal inspiratory pressure in relation to rest (P<0.05). Additionally, there was significant and progressive decrease in low frequency and increase in high frequency at 30%, 60% and 80% of maximal inspiratory pressure in relation to the resting condition.

Conclusion:

These results suggest that respiratory muscle training at high intensities can promote greater parasympathetic activity and it may confer important benefits during a rehabilitation program in post-coronary artery bypass grafting.

Continuous Positive Airway Pressure During Exercise Improves Walking Time in Patients Undergoing Inpatient Cardiac Rehabilitation After Coronary Artery Bypass Graft Surgery: A RANDOMIZED CONTROLLED TRIAL

PURPOSE

Continuous positive airway pressure (CPAP) has been used as an effective support to decrease the negative pulmonary effects of coronary artery bypass graft (CABG) surgery. However, it is unknown whether CPAP can positively influence patients undergoing CABG during exercise. This study evaluated the effectiveness of CPAP on the first day of ambulation after CABG in patients undergoing inpatient cardiac rehabilitation (CR).

METHODS

Fifty-four patients after CABG surgery were randomly assigned to receive either inpatient CR and CPAP (CPG) or standard CR without CPAP (CG). Cardiac rehabilitation included walking and CPAP pressures were set between 10 to 12 cmH2O. Participants were assessed on the first day of walking at rest and during walking. Outcome measures included breathing pattern variables, exercise time in seconds (ETs), dyspnea/leg effort ratings, and peripheral oxygen saturation (SpO2).

RESULTS

Twenty-seven patients (13 CPG vs 14 CG) completed the study. Compared with walking without noninvasive ventilation assistance, CPAP increased ETs by 43.4 seconds (P = .040) during walking, promoted better thoracoabdominal coordination, increased ventilation during walking by 12.5 L/min (P = .001), increased SpO2 values at the end of walking by 2.6% (P = .016), and reduced dyspnea ratings by 1 point (P = .008).

CONCLUSIONS

Continuous positive airway pressure can positively influence exercise tolerance, ventilatory function, and breathing pattern in response to a single bout of exercise after CABG.

Preoperative inspiratory muscle training for postoperative pulmonary complications in adults undergoing cardiac and major abdominal surgery

BACKGROUND

Postoperative pulmonary complications (PPCs) have an impact on the recovery of adults after surgery. It is therefore important to establish whether preoperative respiratory rehabilitation can decrease the risk of PPCs and to identify adults who might benefit from respiratory rehabilitation.

OBJECTIVES

Our primary objective was to assess the effectiveness of preoperative inspiratory muscle training (IMT) on PPCs in adults undergoing cardiac or major abdominal surgery. We looked at all-cause mortality and adverse events.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 10), MEDLINE (1966 to October 2014), EMBASE (1980 to October 2014), CINAHL (1982 to October 2014), LILACS (1982 to October 2014), and ISI Web of Science (1985 to October 2014). We did not impose any language restrictions.

SELECTION CRITERIA

We included randomized controlled trials that compared preoperative IMT and usual preoperative care for adults undergoing cardiac or major abdominal surgery.

DATA COLLECTION AND ANALYSIS

Two or more review authors independently identified studies, assessed trial quality, and extracted data. We extracted the following information: study characteristics, participant characteristics, intervention details, and outcome measures. We contacted study authors for additional information in order to identify any unpublished data.

MAIN RESULTS

We included 12 trials with 695 participants; five trials included participants awaiting elective cardiac surgery and seven trials included participants awaiting elective major abdominal surgery. All trials contained at least one domain judged to be at high or unclear risk of bias. Of greatest concern was the risk of bias associated with inadequate blinding, as it was impossible to blind participants due to the nature of the study designs. We could pool postoperative atelectasis in seven trials (443 participants) and postoperative pneumonia in 11 trials (675 participants) in a meta-analysis. Preoperative IMT was associated with a reduction of postoperative atelectasis and pneumonia, compared with usual care or non-exercise intervention (respectively; risk ratio (RR) 0.53, 95% confidence interval (CI) 0.34 to 0.82 and RR 0.45, 95% CI 0.26 to 0.77). We could pool all-cause mortality within postoperative period in seven trials (431 participants) in a meta-analysis. However, the effect of IMT on all-cause postoperative mortality is uncertain (RR 0.40, 95% CI 0.04 to 4.23). Eight trials reported the incidence of adverse events caused by IMT. All of these trials reported that there were no adverse events in both groups. We could pool the mean duration of hospital stay in six trials (424 participants) in a meta-analysis. Preoperative IMT was associated with reduced length of hospital stay (MD -1.33, 95% CI -2.53 to -0.13). According to the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) Working Group guidelines for evaluating the impact of healthcare interventions, the overall quality of studies for the incidence of pneumonia was moderate, whereas the overall quality of studies for the incidence of atelectasis, all-cause postoperative death, adverse events, and duration of hospital stay was low or very low.

AUTHORS' CONCLUSIONS

We found evidence that preoperative IMT was associated with a reduction of postoperative atelectasis, pneumonia, and duration of hospital stay in adults undergoing cardiac and major abdominal surgery. The potential for overestimation of treatment effect due to lack of adequate blinding, small-study effects, and publication bias needs to be considered when interpreting the present findings.

Efficacy of cardiopulmonary rehabilitation with adaptive servo-ventilation in patients undergoing off-pump coronary artery bypass grafting

BACKGROUND

Postoperative complications after cardiac surgery increase mortality. This study aimed to evaluate the efficacy of cardiopulmonary rehabilitation with adaptive servo-ventilation (ASV) in patients undergoing off-pump coronary artery bypass grafting (OPCAB).

METHODS AND RESULTS

A total of 66 patients undergoing OPCAB were enrolled and divided into 2 groups according to the use of ASV (ASV group, 30 patients; non-ASV group, 36 patients). During the perioperative period, all patients undertook cardiopulmonary rehabilitation. ASV was used from postoperative day (POD) 1 to POD5. Hemodynamics showed a different pattern in the 2 groups. Blood pressure (BP) on POD6 in the ASV group was significantly lower than that in the non-ASV group (systolic BP, 112.9±12.6 vs. 126.2±15.8 mmHg, P=0.0006; diastolic BP, 62.3±9.1 vs. 67.6±9.3 mmHg, P=0.0277). The incidence of postoperative atrial fibrillation (POAF) was lower in the ASV group than in the non-ASV group (10% vs. 33%, P=0.0377). The duration of oxygen inhalation in the ASV group was significantly shorter than that in the non-ASV group (5.1±2.2 vs. 7.6±6.0 days, P=0.0238). The duration of postoperative hospitalization was significantly shorter in the ASV group than in the non-ASV group (23.5±6.6 vs. 29.0±13.1 days, P=0.0392).

CONCLUSIONS

Cardiopulmonary rehabilitation with ASV after OPCAB reduces both POAF occurrence and the duration of hospitalization.

Application of positive airway pressure in restoring pulmonary function and thoracic mobility in the postoperative period of bariatric surgery: a randomized clinical trial

Objective:

To evaluate whether the application of bilevel positive airway pressure in the postoperative period of bariatric surgery might be more effective in restoring lung volume and capacity and thoracic mobility than the separate application of expiratory and inspiratory positive pressure.

Method:

Sixty morbidly obese adult subjects who were hospitalized for bariatric surgery and met the predefined inclusion criteria were evaluated. The pulmonary function and thoracic mobility were preoperatively assessed by spirometry and cirtometry and reevaluated on the 1^st postoperative day. After preoperative evaluation, the subjects were randomized and allocated into groups: EPAP Group (n=20), IPPB Group (n=20) and BIPAP Group (n=20), then received the corresponding intervention: positive expiratory pressure (EPAP), inspiratory positive pressure breathing (IPPB) or bilevel inspiratory positive airway pressure (BIPAP), in 6 sets of 15 breaths or 30 minutes twice a day in the immediate postoperative period and on the 1^st postoperative day, in addition to conventional physical therapy.

Results:

There was a significant postoperative reduction in spirometric variables (p<0.05), regardless of the technique used, with no significant difference among the techniques (p>0.05). Thoracic mobility was preserved only in group BIPAP (p>0.05), but no significant difference was found in the comparison among groups (p>0.05).

Conclusion:

The application of positive pressure does not seem to be effective in restoring lung function after bariatric surgery, but the use of bilevel positive pressure can preserve thoracic mobility, although this technique was not superior to the other techniques.

Respiratory pressures and expiratory peak flow rate of patients undergoing coronary artery bypass graft surgery

Background

To evaluate clinical and laboratorial parameters that predict decreased respiratory function in patients subjected to coronary artery bypass graft surgery (CABG).

Material/Methods

This was a prospective study evaluating 61 patients subjected to CABG with cardiopulmonary bypass, median sternotomy, and under mechanical ventilation for up to 24 h. One day before surgery, clinical information was recorded. Maximal inspiratory (MIP) and expiratory (MEP) pressures, and expiratory peak flow rate (EPFR) values were assessed 1 day before surgery and on the fifth postoperative day. Student’s t test, 2-way ANOVA, Pearson’s linear correlation, and logistic regression were used for statistical analysis.

Results

Patients were 63±10 years old, 67% males. Arterial hypertension was found in 75.4% of the patients, diabetes in 31.2%, dyslipidemia in 63.9%, tabagism in 25%, and chronic obstructive pulmonary disease (COPD) in 16.4%. Previous myocardial infarction was found in 67%. Preoperative hemoglobin levels were 12.8±1.71 g/dL. Older individuals had lower preoperative MEP and EPFR values. Preoperatively, positive association was found between hemoglobin levels and maximal respiratory pressures and EPFR values. Patients with both class III angina and COPD presented higher reductions in pulmonary pressures between the preoperative period and the 5^th postoperative day.

Conclusions

Older age and low hemoglobin levels are associated with preoperative low maximal respiratory pressures and EPFR. The combination of severe angina and COPD results in higher postoperative reduction of maximal respiratory pressures for patients who underwent CABG.

Longitudinal evaluation the pulmonary function of the pre and postoperative periods in the coronary artery bypass graft surgery of patients treated with a physiotherapy protocol

Background

The treatment of coronary artery disease (CAD) seeks to reduce or prevent its complications and decrease morbidity and mortality. For certain subgroups of patients, coronary artery bypass graft surgery (CABG) may accomplish these goals. The objective of this study was to assess the pulmonary function in the CABG postoperative period of patients treated with a physiotherapy protocol.

Methods

Forty-two volunteers with an average age of 63 ± 2 years were included and separated into three groups: healthy volunteers (n = 09), patients with CAD (n = 9) and patients who underwent CABG (n = 20). Patients from the CABG group received preoperative and postoperative evaluations on days 3, 6, 15 and 30. Patients from the CAD group had evaluations on days 1 and 30 of the study, and the healthy volunteers were evaluated on day 1. Pulmonary function was evaluated by measuring forced vital capacity (FVC), maximum expiratory pressure (MEP) and Maximum inspiratory pressure (MIP).

Results

After CABG, there was a significant decrease in pulmonary function (p < 0.05), which was the worst on postoperative day 3 and returned to the preoperative baseline on postoperative day 30.

Conclusion

Pulmonary function decreased after CABG. Pulmonary function was the worst on postoperative day 3 and began to improve on postoperative day 15. Pulmonary function returned to the preoperative baseline on postoperative day 30.

Inspiratory muscle strength as a determinant of functional capacity early after coronary artery bypass graft surgery

Stein R, Maia CP, Silveira AD, Chiappa GR, Myers J, Ribeiro JP. Inspiratory muscle strength as a determinant of functional capacity early after coronary artery bypass graft surgery.

OBJECTIVE

To evaluate the effects of a 6-day postoperative in-hospital cardiopulmonary rehabilitation program on inspiratory muscle strength and its potential association with improved functional capacity after coronary artery bypass graft (CABG) surgery.

DESIGN

Prospective, randomized controlled trial.

SETTING

Tertiary public hospital in Brazil.

PARTICIPANTS

Men (N=20) after CABG were randomized to cardiopulmonary rehabilitation (n=10; age, 64+/-8y) or to usual care (n=10; age, 63+/-7y).

INTERVENTIONS

Ten subjects underwent a 6-day postoperative in-hospital program, which included the use of expiratory positive airway pressure mask and bronchial hygiene techniques, coupled with progressive distance walking and calisthenics as well as cardiopulmonary training. Ten controls were followed by their own physicians and received routine nursing assistance but were not exposed to any specific respiratory or motor physical intervention.

MAIN OUTCOME MEASURES

Maximal inspiratory and expiratory pressure were measured by a pressure transducer, and the highest pressure obtained in 6 measurements was used for analysis (before surgery, and 7 and 30d after surgery). The six-minute walk test (6MWT) was performed 7 days after surgery, and maximal cardiopulmonary exercise testing was performed 30 days after CABG.

RESULTS

After randomization, clinical and functional characteristics were similar in the 2 groups. Rehabilitation resulted in maintenance of maximal inspiratory pressure (PImax) measured at 7 and 30 days postoperatively, respectively (from 68+/-19% at baseline to 58+/-22% and to 61+/-22% predicted), while it was significantly reduced in the control group. 6MWT distance was longer 7 days after CABG in rehabilitation subjects (416+/-78m) than controls (323+/-67m). Peak oxygen uptake (Vo(2)peak) at day 30 was also higher (28%) in the rehabilitation group and was correlated with PImax (r=.90).

CONCLUSIONS

A 6-day rehabilitation program attenuated the postoperative reduction in respiratory muscle strength and also improved the recovery of functional capacity after CABG. The correlation between PImax and Vo(2)peak during the late postoperative period suggests that inspiratory muscle strength is an important determinant of functional capacity after CABG.

Acute application of bilevel positive airway pressure influences the cardiac autonomic nervous system

INTRODUCTION

Noninvasive positive pressure has been used to treat several diseases. However, the physiological response of the cardiac autonomic system during bilevel positive airway pressure (Bilevel) remains unclear.

OBJECTIVE

The aim of this study was to evaluate the heart rate variability (HRV) during Bilevel in young healthy subjects.

METHODS

Twenty men underwent 10-minute R-R interval recordings during sham ventilation (SV), Bilevel of 8-15 cmH(2)O and Bilevel of 13-20 cmH(2)O. The HRV was analyzed by means of the parallel R-R interval (mean R-Ri), the standard deviation of all R-Ri (SDNN), the root mean square of the squares of the differences between successive R-Ri (rMSSD), the number of successive R-Ri pairs that differ by more than 50 milliseconds (NN50), the percentage of successive R-Ri that differ by more than 50 milliseconds (pNN50), the low frequency (LF), the high frequency (HF) and SD1 and SD2. Additionally, physiological variables, including blood pressure, breathing frequency and end tidal CO(2), were collected. Repeated-measures ANOVA and Pearson correlation were used to assess the differences between the three studied conditions and the relationships between the delta of Bilevel at 13-20 cmH(2)O and sham ventilation of the HRV indexes and the physiological variables, respectively.

RESULTS

The R-Ri mean, rMSSD, NN50, pNN50 and SD1 were reduced during Bilevel of 13-20 cmH(2)O as compared to SV. An R-Ri mean reduction was also observed in Bilevel of 13-20 cmH(2)O compared to 8-15 cmH(2)O. Both the R-Ri mean and HF were reduced during Bilevel of 8-15 cmH(2)O as compared to SV, while the LF increased during application of Bilevel of 8-15 cmH(2)O as compared to SV. The delta (between Bilevel at 13-20 cmH(2)O and sham ventilation) of ETCO(2) correlated positively with LF, HF, the LF/HF ratio, SDNN, rMSSD and SD1. Acute application of Bilevel was able to alter the cardiac autonomic nervous system, resulting in a reduction in parasympathetic activity and an increase in sympathetic activity and higher level of positive pressure can cause a greater influence on the cardiovascular and respiratory system.

Noninvasive ventilation acutely modifies heart rate variability in chronic obstructive pulmonary disease patients

OBJECTIVE

The purpose of present study was to evaluate the acute effects of bi-level positive airway pressure (BiPAP) on heart rate variability (HRV) of stable chronic obstructive pulmonary disease patients (COPD).

METHODS

Nineteen males with COPD (69+/-8 years and with forced expiratory volume in 1s <50% of predicted) and eight healthy sedentary age-matched (69 years) males in the control group (CG) were evaluated during two conditions of controlled respiratory rate: spontaneous breathing (SB) and BiPAP (inspiratory and expiratory levels between 12-14 cmH(2)O and 4-6 cmH(2)O, respectively). Peripheral oxygen saturation (SpO(2)), end-tidal of carbon dioxide (ETCO(2)), systolic blood pressure (SBP) and R-R interval were obtained. HRV was analyzed by time (RMSSD and SDNN index) and frequency domains (high frequency - HF, low frequency - LF and HF/LF ratio).

RESULTS

Significant reduction of ETCO(2) and SBP in both groups and increase of SpO(2) in COPD group was observed during BiPAP ventilation (p<0.05). During spontaneous breathing, patients with COPD presented lower values of LF, LF/HF and higher values of HF when compared to CG (p<0.05). However, HF was significantly reduced and LF increased during BiPAP ventilation (58+/-19-48+/-15 and 41+/-19-52+/-15 un, respectively) in COPD group. Significant correlations between delta BiPAP-SB (Delta) ETCO(2) and DeltaHF were found (r=0.89).

CONCLUSIONS

Sympathetic and parasympathetic neural control of heart rate is altered in COPD patients and that BiPAP acutely improves ventilation, enhances sympathetic response and decreases vagal tonus. The improvement of ventilation caused by BiPAP was associated with reduced cardiac vagal activity in stable moderate-to-severe COPD patients.