Deep-Breathing Exercises Reduce Atelectasis and Improve Pulmonary Function After Coronary Artery Bypass Surgery* Elisabeth Westerdahl, RPT, PhD; Birgitta Lindmark, RPT, PhD; ¨ rjan Friberg, MD; Tomas Eriksson, MD; O Go¨ran Hedenstierna, MD, PhD, FCCP; and Arne Tenling, MD, PhD

Study objectives: To investigate the effects of deep-breathing exercises on pulmonary function, atelectasis, and arterial blood gas levels after coronary artery bypass graft (CABG) surgery. Design, setting, and patients: In a prospective, randomized trial, patients performing deepbreathing exercises (n ⴝ 48) were compared to a control group (n ⴝ 42) who performed no breathing exercises postoperatively. Patient management was similar in the groups in terms of assessment, positioning, and mobility. Interventions: The patients in the deep-breathing group were instructed to perform breathing exercises hourly during daytime for the first 4 postoperative days. The exercises consisted of 30 slow, deep breaths performed with a positive expiratory pressure blow-bottle device (ⴙ 10 cm H2O). Measurements and results: Spirometric measurements, spiral CT (three transverse levels), arterial blood gas analysis, and scoring of subjective experience of the breathing exercises were performed on the fourth postoperative day. Atelectasis was only half the size in the deepbreathing group compared to the control group, amounting to 2.6 ⴞ 2.2% vs 4.7 ⴞ 5.7% (p ⴝ 0.045) at the basal level and 0.1 ⴞ 0.2% vs 0.3 ⴞ 0.5% (mean ⴞ SD) [p ⴝ 0.01] at the apical level. Compared to the control subjects, the patients in the deep-breathing group had a significantly smaller reduction in FVC (to 71 ⴞ 12%, vs 64 ⴞ 13% of the preoperative values; p ⴝ 0.01) and FEV1 (to 71 ⴞ 11%, vs 65 ⴞ 13% of the preoperative values; p ⴝ 0.01). Arterial oxygen tension, carbon dioxide tension, fever, or length of ICU or hospital stay did not differ between the groups. In the deep-breathing group, 72% of the patients experienced a subjective benefit from the exercises. Conclusions: Patients performing deep-breathing exercises after CABG surgery had significantly smaller atelectatic areas and better pulmonary function on the fourth postoperative day compared to a control group performing no exercises. (CHEST 2005; 128:3482–3488) Key words: atelectasis; breathing exercises; cardiac surgery; coronary artery bypass; CT; physical therapy; postoperative care; postoperative complications; thoracic surgery Abbreviations: BMI ⫽ body mass index; CABG ⫽ coronary artery bypass graft; FRC ⫽ functional residual capacity; HU ⫽ Hounsfield unit; IC ⫽ inspiratory capacity; PEP ⫽ positive expiratory pressure; VC ⫽ vital capacity

and arterial hypoxemia are commonly A telectasis seen after cardiac surgery. Chest physical therapy is widely used postoperatively for the prevention of pulmonary complications. A variety of treatment techniques are used, and there are differences in the management between *From the Department of Medical Sciences, Clinical Physiology (Drs. Westerdahl and Hedenstierna) and Department of Neuroscience, Section of Physiotherapy (Dr. Lindmark), University Hospital, Uppsala; the Departments of Cardiothoracic Surgery ¨ rebro University (Dr. Friberg) and Radiology (Dr Eriksson), O ¨ rebro; and the Department of Cardiothoracic AnesHospital, O thesia (Dr, Tenling), Karolinska University Hospital, Huddinge, Sweden.

countries. In later years, the routine use of breathing exercises after cardiac surgery has been questioned. Breathing exercises combined with physical therapy This study was supported by financial grants from the Heart and Lung Patients National Association, Sweden; the Karolinska ¨ rebro County Institute, Stockholm; the Research Committee of O ¨ rebro; and the Swedish Heart Lung Foundation and Council, O Uppsala University. Manuscript received July 9, 2004; revision accepted June 9, 2005. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal. org/misc/reprints.shtml). Correspondence to: Elisabeth Westerdahl, RPT, PhD, Depart¨ rebro University Hospital, SE-701 85 ment of Physiotherapy, O ¨ rebro, Sweden; e-mail: [email protected] O

3482

Downloaded From: http://journal.publications.chestnet.org/pdfaccess.ashx?url=/data/journals/chest/22033/ on 01/17/2017

Clinical Investigations

after coronary artery bypass graft (CABG) surgery have been reported not to be more effective than physical therapy, including early mobilization alone in reducing atelectasis,1 pneumonia,2 gas exchange and lung function impairment,3 or other kinds of pulmonary complications.4,5 Pasquina et al6 concluded that evidence is lacking on benefit from any method of prophylactic respiratory physical therapy after cardiac surgery, and that it is more comprehensive than justified by findings of clinical research. We have shown7 an immediate effect of a single session of voluntary deep-breathing exercises on atelectasis and oxygenation on the second postoperative day after CABG surgery. Incentive spirometry remains a frequently used technique for the prophylaxis and treatment of respiratory complications in postsurgical patients, but the evidence does not support the use of incentive spirometry for decreasing the incidence of atelectasis and pulmonary complications following cardiac surgery.1,8,9 The objective of this study was to evaluate the effectiveness of voluntary deep-breathing exercises performed with a positive expiratory pressure (PEP) blow-bottle device on pulmonary function, atelectasis, arterial blood gas levels, and subjective experience in CABG patients compared to a control group who performed no breathing exercises.

Materials and Methods Patients A sample of 115 patients undergoing CABG surgery at a university hospital were invited to participate in the study. Patients who had an emergency operation, previous cardiac surgery, severe renal dysfunction, or difficulties in cooperating during measurements were not included. Three patients declined participation. The patients were randomized to a deep-breathing group (n ⫽ 57) that performed deep-breathing exercises postoperatively and to a control group (n ⫽ 55) that performed no breathing exercises. Informed consent was obtained from each patient, and the study was approved by the local research ethics committee. Surgical and Postoperative Procedure All patients received general anesthesia, and the CABG was performed with saphenous veins and in most cases the left internal mammary artery. During anesthesia and following surgery, all patients inspired oxygen with a concentration of 40 to 80%. The surgical approach was through a median sternotomy. Cold-blood cardioplegia and occasionally topical cooling of the heart were used. An insulation pad was used to protect the phrenic nerve. The pericardium, the mediastinum and, occasionally one or both pleura were drained, usually ⬍ 24 h after surgery. Postoperatively, the patients received mechanical ventilation with a positive end-expiratory pressure of 5 to 10 cm H2O. The patients were extubated when they had resumed normothermia, were hemodynamically stable, had adequate diuresis and no www.chestjournal.org

severe bleeding in the drain, and were able to breathe normally without distress, in accordance with the ordinary clinical routines. Pain All patients were administered pain relief according to standard routines at the clinic. At the time of the pulmonary function test on the fourth postoperative day, the patients were asked to quantify the pain from the median sternotomy incision. A continuous visual analog scale from 0 (no pain) to 10 (the worst imaginable pain) was used. Study Groups and Chest Physical Therapy The day before the operation, or the week before if operated on a Monday, the patients received general information about postoperative routines by one of three physical therapists. All patients received chest physical therapy once or twice daily as normally performed at the clinic during the first 4 postoperative days. Therapy consisted of early mobilization, instructions in efficient coughing techniques, daily active exercises of the shoulder girdle and upper back and instructions, and assistance to turn from side to side and get out of bed. The patients were mobilized as early as possible by the nursing staff. The patients were sitting out of bed and/or standing on the first postoperative day, walked in the room or a short distance in the corridor on the second day, and walking a longer distance in the corridor on the third postoperative day. On the third and fourth postoperative days, the patients participated in a sitting group exercise program. The patients in the deep-breathing group were informed and practiced the breathing technique preoperatively. The exercises were started approximately 1 h after extubation, and the patients were encouraged to perform 30 deep breaths once per hour when awake (in daytime) for the first 4 postoperative days. The exercise included three sets of 10 deep breaths with a 30- to 60-s pause between each set. If needed, the patients were asked to cough during the pause to mobilize secretions. The patients were instructed to perform the deep breathing in the sitting position, if possible. A 50-cm plastic tube (1 cm in internal diameter) in a bottle containing 10 cm of water (the “blow-bottle”) was used to create an expiratory resistance of ⫹ 10 cm H2O. If the patient initially was unable to expire through the tube, a PEP/respiratory muscle training facemask (Astra Tech AB; Mo¨lndal, Sweden) was used to create the expiratory pressure. One of three experienced physical therapists supervised the breathing exercises, and the patients were instructed to perform slow maximal inspirations, while expiration was aimed to end approximately at functional residual capacity (FRC) to minimize airway closure and alveolar collapse. Compliance with treatment was documented in the patient record until the morning of the second postoperative day, and after that it was self-reported. The patients in the control group were not instructed to do any breathing exercises. Measurements Pulmonary function measurements were performed preoperatively and on the fourth postoperative day (Jaeger MasterScreen PFT/Bodybox; Spiropharma Cardiopulmonary Diagnostics; Klampenborg, Denmark) with proprietary software. The equipment was calibrated every morning prior to measurements. Six medical laboratory technicians who were unaware of the patient’s randomization performed the tests. The patients were in a sitting position, and a nose clip was used. Predicted values for pulmonary function were related to age, sex, and height according to the values reported by Quanjer et al.10 Spirometry was performed according to the recommendations of the European Respiratory CHEST / 128 / 5 / NOVEMBER, 2005

Downloaded From: http://journal.publications.chestnet.org/pdfaccess.ashx?url=/data/journals/chest/22033/ on 01/17/2017

3483

Society. The highest value of three technically satisfactory maneuvers was retained. First an inspiratory maneuver was obtained for measurement of vital capacity (VC). Then measurements of FVC and FEV1 were performed, followed by recording of the inspiratory capacity (IC) and FRC. Total lung capacity (TLC) was calculated as FRC ⫹ IC. Atelectasis and aeration of the lungs were assessed by spiral CT (Philips CT Secura; Philips Medical Systems; Eindhoven, the Netherlands)11–13 on the fourth postoperative day. The patients were transported to the Department of Radiology in a wheelchair. One radiologist and one radiographer who were blinded to study group assignments made all measurements. The patients lay in the supine position with their arms raised above their heads, and the examination was made during apnea at FRC. First, a frontal scanogram covering the chest was obtained for positioning. The scan time was 9 s for a 12-cm volume scan at 280 mA and 120 kV. Slice thickness was 1.0 cm, and a matrix of 512 ⫻ 512 elements was used. The total estimated effective dose was 1.5 millisieverts. Three of the CT scans were used for subsequent analysis, positioned 1 cm, 5 cm, and 9 cm above the top of the right diaphragm. A radiologist delineated the lung area manually from the inner margins of the thoracic cage, excluding pleural fluid and tissue between the ribs, mediastinum, or any part of the diaphragm. The computer identified the border between inflated lung tissue and atelectasis. Aerated lung area was defined as volume elements with attenuation values between ⫺ 100 Hounsfield units (HU) and ⫺ 1,000 HU, and atelectasis was defined as values between ⫹ 100 and ⫺ 100 HU.12,14 The most cephalad point of the diaphragm was determined in relation to the carina. Arterial blood gas measurements were done before induction of anesthesia and on the fourth postoperative day for blood gas analysis (Radiometer ABL 505; Inter Bio-Lab; Orlando, FL). The patients had been without supplementary oxygen for ⱖ 15 min. Body temperature was measured preoperatively and on postoperative days 1, 2, 3, and 4. On the fourth postoperative day, the patients in the deep-breathing group were asked to score their subjective benefit and/or discomfort of the breathing exercise on an arbitrary scale. Statistical Analysis All data were collected and analyzed in a statistical computer program (StatView; Abacus Concepts; Berkeley, CA) and presented as mean values ⫾ SD. Baseline data were compared by unpaired t test or by ␹2 test. The relative decrease in pulmonary function after the operation, the atelectatic area, and arterial blood gases were compared by an unpaired t test. Including 45 patients per group would yield 80% power (␣ ⫽ 0.05) to detect a decrease from 2.5 to 1.9% (percentage reduction, 20 to 25%) in bilateral atelectatic area in percentage of total lung area between groups, assuming a SD of 1.0%. This difference is assumed by the authors to be of clinical relevance. Dropout was anticipated to be up to 20%, and hence another 10 patients were included in each group. All results refer to two-sided tests, and p ⬍ 0.05 was considered significant.

Results Five women and 17 men (mean age ⫾ SD, 68 ⫾ 11 years) were excluded for various reasons, as reported in Table 1. In total, 90 patients (23 women and 67 men) were investigated. Demographic (Table 2) and surgical (Table 3) data did not significantly

Table 1—Causes of Exclusion From the Study*

Causes Circulatory instability Respiratory instability Neurologic complication Reoperation Pneumothorax Pleural effusion (⬎ 3 cm) Sternal infection Failure to cooperate Ad mortem

Treatment Group (n ⫽ 9)

Control Group (n ⫽ 13)

1 1 1

2 1 1 1 3 3 1 1

1 4

1

*Data are presented as No.

differ between the two groups. Pain from the sternotomy did not differ between the two groups. Mean value for the visual analog scale at rest was 1.4 ⫾ 1.6 cm; while taking a deep breath, 2.5 ⫾ 2.1 cm; while coughing, 4.3 ⫾ 2.8 cm; and during pulmonary function testing, 2.4 ⫾ 2.2 cm. No significant differences in length of ICU stay (deep-breathing group, 17.9 ⫾ 5.3 h; control group, 18.8 ⫾ 4.0 h), postoperative hospital stay (5.5 ⫾ 2.8 days vs 5.3 ⫾ 2.6 days), or fever (mean value for the 4 postoperative days, 37.5 ⫾ 0.3°C vs 37.6 ⫾ 0.4°C) were noticed. None of the patients had signs of pneumonia during the hospital stay. One of the excluded patients received antibiotics because of a sternal infection. Pulmonary Function The preoperative lung function showed a VC at or below ⫺ 2 SD in five patients in the treatment group and one patient in the control group. There was no

Table 2—Demographic Data*

Variables Male/female gender Age, yr Weight, kg Height, cm BMI, kg/m2 Smoking status Never Stopped Current smoker New York Heart Association class I-II IIIA-B IV Left ventricular ejection fraction, %

Treatment Group (n ⫽ 48)

Control Group (n ⫽ 42)

36/12 66 ⫾ 9 80 ⫾ 15 171 ⫾ 8 27 ⫾ 4

31/11 65 ⫾ 9 81 ⫾ 12 172 ⫾ 8 27 ⫾ 3

21 17 10

16 20 6

14 32 2 56 ⫾ 14

16 22 1 54 ⫾ 14

*Data are presented as mean ⫾ SD or No. of patients. No significant differences were found between groups.

3484

Downloaded From: http://journal.publications.chestnet.org/pdfaccess.ashx?url=/data/journals/chest/22033/ on 01/17/2017

Clinical Investigations

Table 3—Surgical Data*

Variables

Treatment Group (n ⫽ 48)

Control Group (n ⫽ 42)

Operation time, h Extracorporeal circulation time, min Aortic occlusion time, min Saphenous vein grafts, per patient Left internal mammary artery graft Left pleural space entered Bilateral pleural space entered Postoperative mechanical ventilation, h

2.5 ⫾ 0.8 79 ⫾ 18 47 ⫾ 15 3.6 ⫾ 0.9 46 36 5 5.0 ⫾ 2.1

2.8 ⫾ 0.8 83 ⫾ 27 49 ⫾ 16 4.0 ⫾ 1.1 40 26 8 5.0 ⫾ 1.7

*Data are presented as mean ⫾ SD or No. of patients. No significant differences were found between groups.

significant difference between the two groups. On the fourth postoperative day, the patients in the deep-breathing group had a significantly smaller reduction in FVC, down to 71 ⫾ 12% of the preoperative value, than patients in the control group (64 ⫾ 13%; p ⫽ 0.01). Similarly, FEV1 was reduced less in the deep-breathing group than the control group, to 71 ⫾ 11% vs 65 ⫾ 13% of the preoperative values (p ⫽ 0.01; Fig 1). Atelectasis Four days after CABG surgery, all examined patients had signs of atelectasis (missing data in the treatment group [n ⫽ 11] and in the control group [n ⫽ 6] because of technical and scheduling difficulties). The atelectatic area was largest at the basal

level, close to the diaphragm, and minor at the upper level, near the apex. A significantly smaller atelectatic area in the deep-breathing group, of one half the size, compared to the control group (p ⬍ 0.05) was found at the basal and apical levels. The mean values from both lungs at the three CT levels are shown in Table 4, and examples of CT scans are shown in Figure 2. The amount of atelectasis at the basal level (in percentage of the total lung area) correlated to FEV1 on the fourth postoperative day (r ⫽ ⫺ 0.32, r2 ⫽ 0.10, p ⬍ 0.01) as well as to the postoperative relative decrease in FEV1 (r ⫽ ⫺ 0.37, r2 ⫽ 0.14, p ⬍ 0.01). Patients with a body mass index (BMI) ⬎ 30 (n ⫽ 19) had the same amount of atelectasis as those with a BMI ⬍ 30; there no significant differences in the results of breathing exercises between the groups. The distance between the diaphragm and the carina did not differ between the treatment group (7.8 ⫾ 1.6 cm in the right lung and 9.9 ⫾ 1.3 cm in the left lung) and in the control group (7.9 ⫾ 1.6 cm and 9.2 ⫾ 1.8 cm, respectively). Arterial Blood Gas Levels No significant differences in Pao2, arterial oxygen saturation, or Paco2 between the two groups were found (Table 5). Subjective Experience and Self-Report of the Breathing Exercises All 46 patients (2 patients with missing data) in the deep-breathing group answered that the breathing

Figure 1. Pulmonary function values on the fourth postoperative day in percentage of preoperative values in the treatment group, performing deep-breathing exercises, and the control group. Error lines indicate 95% confidence intervals; p values refer to the difference in pulmonary function between the deep-breathing group and the control group. *p ⬍ 0.05. TLC ⫽ total lung capacity. www.chestjournal.org

CHEST / 128 / 5 / NOVEMBER, 2005

Downloaded From: http://journal.publications.chestnet.org/pdfaccess.ashx?url=/data/journals/chest/22033/ on 01/17/2017

3485

Table 4 —Atelectasis on the Fourth Postoperative Day* CT Level†

Treatment Group (n ⫽ 37)

Control Group (n ⫽ 36)

p Value‡

Upper Middle Basal Total

0.1 ⫾ 0.2 (0.1 ⫾ 0.3) 0.7 ⫾ 0.6 (1.2 ⫾ 1.1) 2.6 ⫾ 2.2 (4.9 ⫾ 3.7) 1.2 ⫾ 0.8 (8.5 ⫾ 5.9)

0.3 ⫾ 0.5 (0.4 ⫾ 0.6) 1.3 ⫾ 2.2 (2.0 ⫾ 2.8) 4.7 ⫾ 5.7 (7.3 ⫾ 7.5) 2.2 ⫾ 2.8 (13.0 ⫾ 13.6)

0.011 0.09 0.045 0.046

*Data are presented as mean ⫾ SD areas of bilateral atelectasis in % of total lung area (cm2). †The basal level is 1 cm above the top of the diaphragm, the middle level is 5 cm above the top of the diaphragm, and the upper level is 9 cm above the top of the diaphragm. The total atelectatic area is the mean of both lungs at the three CT levels. ‡Difference in atelectasis in % of total lung area between the deep-breathing group and the control group.

technique was easy to perform. Of these, 33 patients (72%) experienced a subjective benefit of the exercises, 2 patients found no benefit, and 11 patients had no opinion. Only five patients experienced discomfort during the exercises. The patients answered that they had performed the deep-breathing exercises 7 ⫾ 2 times per day (range, 2 to 12 times per day) postoperatively and that each session had consisted of 25 ⫾ 8 breaths (range, 8 to 30 breaths). Discussion In the present investigation, it was found that chest physical therapy including deep-breathing exercises significantly decreased atelectasis and improved spirometry values compared to a regime without breathing instructions following CABG surgery. Atelectasis on the fourth postoperative day was decreased by one half compared to the control group. The amount of atelectasis in the lungs expressed in percentage of the total transverse lung area was less in the present study (2 to 5% just above the diaphragm) than in a study7 performed on the

second postoperative day (10 to 12%) after CABG surgery. A decrease of atelectasis during the succeeding postoperative days has been shown after abdominal surgery,15 and a similar spontaneous recovery after cardiac surgery could be expected. Another possible explanation could be better preservation of pulmonary function because of shorter operation and extracorporeal circulation time in the present study. However, between the two groups we saw no difference in ICU or hospital stay, and there were no records of pulmonary infection in any patient. It must be clear that the study was not designed to evaluate clinical outcome: the material was too small and limited by the inclusion of CT in the study. Atelectasis could be a reason for pneumonia, but the diagnosis should be based on the presence of clinical signs and symptoms of pneumonia coupled with the identification of pathogenic bacteria, rather than radiographic identification of atelectasis.16,17 Despite the common use of breathing exercises in the management of CABG patients in many countries, scientific evidence for the efficacy of this treatment has been lacking.1,4,5,9 The physical therapy treatment has even been considered to cause adverse effects and costs only.6 In a previous investigation,7 we showed an immediate decrease in atelectatic area and an increase in oxygenation after a session of 30 deep breaths performed on the second postoperative day after CABG surgery. The effect was achieved by just one series of deep breathing; however, no significant differences between patients performing the breathing with or without a PEP device were present. In the present investigation, we examined deep breathing performed with a blow-bottle device because it is the standard technique at the university hospital where the study took place. The focus was to facilitate deep breaths, and the patients were instructed to perform

Figure 2. CT scans of a patients in the control group (left) and the treatment group (right) 1 cm above the diaphragm on the fourth postoperative day. Left: Atelectatic areas of 6 cm2 in the right lung and 7 cm2 in the left lung. Right: Atelectatic areas of 1 cm2 in the respective lungs. 3486

Downloaded From: http://journal.publications.chestnet.org/pdfaccess.ashx?url=/data/journals/chest/22033/ on 01/17/2017

Clinical Investigations

Table 5—Arterial Blood Gas Analysis* Before Surgery

After Surgery

Variables

Treatment Group

Control Group

Treatment Group

Control Group

p Value†

Pao2, kPa Sao2 , % Paco2, kPa

9.7 ⫾ 1.5 94.2 ⫾ 4.0 5.8 ⫾ 0.8

9.8 ⫾ 1.1 94.9 ⫾ 2.3 6.0 ⫾ 0.7

8.7 ⫾ 1.2 92.6 ⫾ 3.1 5.1 ⫾ 0.5

9.0 ⫾ 1.2 93.3 ⫾ 1.9 5.0 ⫾ 0.4

0.49 0.91 0.17

*Data are presented as mean (⫾ SD). The measurements were performed before and four days after surgery. Sao2 ⫽ arterial oxygen saturation. †Difference between the deep-breathing group and the control group.

maximal slow inspirations. The expiration was relaxed, and an expiratory pressure of 10 cm H2O was achieved if the patients were breathing out correctly. It is possible that the same results could have been obtained even without using the blow-bottle device.7 The patients were encouraged to perform the deep-breathing exercises once per hour throughout the day. The frequency (three sets of 10 breaths) was chosen according to the ordinary routines at the clinic. Compliance with the suggested exercises was not objectively measured, but it was self-reported by the patients in the deep-breathing group. The reported number of exercise sessions performed each day might be considered acceptable and is in accordance with what one can achieve in a clinical situation. At present, it is not known if increasing the frequency and intensity of the exercises is likely to be more efficacious. All patients found the breathing technique easy to perform, and most of the patients experienced a subjective benefit of the exercises; this is important for completion of the treatment. In our study, pulmonary function measurement was performed preoperatively and repeated on the fourth postoperative day. A marked reduction in lung volumes was present on the fourth postoperative day, which was of the same extent as found in previous investigations after CABG surgery.18 –20 A slightly better preservation of spirometric variables was also seen in the deep-breathing group compared to the control group on the fourth postoperative day; however, the effect on atelectasis was more obvious than the spirometric results. However, a correlation was found between atelectasis and worsening in FEV1, similar to a previous study15 on postoperative atelectasis after abdominal surgery. CT can give reliable measurement of atelectasis, but it is worth noting that up to this time CT has not been used in the evaluation of prophylactic chest physical therapy following cardiac surgery. Clear effects of deep breathing on pulmonary function parameters after cardiac surgery have earlier not been documented, and this could possibly be explained by the choice of outcome measures. Studies including control group patients who did not receive chest physiotherapy at all have been limited,3,4 and www.chestjournal.org

none of these studies have shown benefits from treatment regimens. Even though our patients were seen by a physical therapist daily and were instructed in active exercises and mobilized early, the patients in the deep-breathing group still had better pulmonary function and smaller atelectatic areas. A weak correlation between atelectatic areas and Pao2 has earlier been presented,7 but in the present study no significant difference in oxygenation was apparent between the deep-breathing group and the control group. Recruited lung tissue is most likely converted from a shunt region to a zone with low ventilation in relation to perfusion, still contributing to poor oxygenation of blood.21,22 Arterial oxygenation is also influenced by nonpulmonary factors such as mixed venous oxygen tension or cardiac output and efficiency of hypoxic pulmonary vasoconstriction.23 It should also be emphasized that atelectasis is a locus for inflammation. A variety of signs and symptoms can identify a postoperative pulmonary complication. The presence of atelectasis in combination with other chosen factors is often a criterion for the definition. Whether a reduced amount of atelectasis can decrease postoperative lung complications, if atelectasis is not considered a complication, remains to be tested. Conclusion Patients who performed deep-breathing exercises after CABG surgery showed a significantly smaller amount of atelectasis and had less reduction in FVC and FEV1 on the fourth postoperative day compared to patients who performed no breathing exercises. ACKNOWLEDGMENT: We thank the staff at the Departments of Cardiothoracic Surgery, Physiotherapy, and Clinical Physiology for support and measurements, and Martin Gustavsson, ¨ rebro University Hospital, for perDepartment of Radiology, O forming all CT measurements.

References 1 Crowe JM, Bradley CA. The effectiveness of incentive spirometry with physical therapy for high-risk patients after CHEST / 128 / 5 / NOVEMBER, 2005

Downloaded From: http://journal.publications.chestnet.org/pdfaccess.ashx?url=/data/journals/chest/22033/ on 01/17/2017

3487

coronary artery bypass surgery. Phys Ther 1997; 77:260 –268 2 Johnson D, Kelm C, To T, et al. Postoperative physical therapy after coronary artery bypass surgery. Am J Respir Crit Care Med 1995; 152:953–958 3 Jenkins SC, Soutar SA, Loukota JM, et al. Physiotherapy after coronary artery surgery: are breathing exercises necessary? Thorax 1989; 44:634 – 639 4 Stiller K, Montarello J, Wallace M, et al. Efficacy of breathing and coughing exercises in the prevention of pulmonary complications after coronary artery surgery. Chest 1994; 105:741–747 5 Brasher PA, McClelland KH, Denehy L, et al. Does removal of deep breathing exercises from a physiotherapy program including pre-operative education and early mobilisation after cardiac surgery alter patient outcomes? Aust J Physiother 2003; 49:165–173 6 Pasquina P, Tramer MR, Walder B. Prophylactic respiratory physiotherapy after cardiac surgery: systematic review. BMJ 2003; 327:1379 7 Westerdahl E, Lindmark B, Eriksson T, et al. The immediate effects of deep breathing exercises on atelectasis and oxygenation after cardiac surgery. Scand Cardiovasc J 2003; 37:363– 367 8 Matte P, Jacquet L, Van Dyck M, et al. Effects of conventional physiotherapy, continuous positive airway pressure and non-invasive ventilatory support with bilevel positive airway pressure after coronary artery bypass grafting. Acta Anaesthesiol Scand 2000; 44:75– 81 9 Overend TJ, Anderson CM, Lucy SD, et al. The effect of incentive spirometry on postoperative pulmonary complications: a systematic review. Chest 2001; 120:971–978 10 Quanjer PH, Tammeling GJ, Cotes JE, et al. Lung volumes and forced ventilatory flows: Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal; Official Statement of the European Respiratory Society. Eur Respir J Suppl 1993; 16:5– 40 11 Brismar B, Hedenstierna G, Lundquist H, et al. Pulmonary densities during anesthesia with muscular relaxation: a proposal of atelectasis. Anesthesiology 1985; 62:422– 428 12 Lundquist H, Hedenstierna G, Strandberg A, et al. CT-

13 14

15 16 17 18

19

20 21

22

23

assessment of dependent lung densities in man during general anaesthesia. Acta Radiol 1995; 36:626 – 632 Hedenstierna G, Lundquist H, Lundh B, et al. Pulmonary densities during anaesthesia: an experimental study on lung morphology and gas exchange. Eur Respir J 1989; 2:528 –535 Gattinoni L, Pesenti A, Bombino M, et al. Relationships between lung computed tomographic density, gas exchange, and PEEP in acute respiratory failure. Anesthesiology 1988; 69:824 – 832 Lindberg P, Gunnarsson L, Tokics L, et al. Atelectasis and lung function in the postoperative period. Acta Anaesthesiol Scand 1992; 36:546 –553 Johnson NT, Pierson DJ. The spectrum of pulmonary atelectasis: pathophysiology, diagnosis, and therapy. Respir Care 1986; 31:1107–1120 Woodring JH, Reed JC. Types and mechanisms of pulmonary atelectasis. J Thorac Imaging 1996; 11:92–108 Westerdahl E, Lindmark B, Almgren SO, et al. Chest physiotherapy after coronary artery bypass graft surgery: a comparison of three different deep breathing techniques. J Rehabil Med 2001; 33:79 – 84 Oikkonen M, Karjalainen K, Kahara V, et al. Comparison of incentive spirometry and intermittent positive pressure breathing after coronary artery bypass graft. Chest 1991; 99:60 – 65 Jenkins SC, Soutar SA, Forsyth A, et al. Lung function after coronary artery surgery using the internal mammary artery and the saphenous vein. Thorax 1989; 44:209 –211 Anjou-Lindskog E, Broman L, Broman M, et al. Effects of oxygen on central haemodynamics and VA/Q distribution after coronary bypass surgery. Acta Anaesthesiol Scand 1983; 27:378 –384 Rothen HU, Sporre B, Engberg G, et al. Influence of gas composition on recurrence of atelectasis after a reexpansion maneuver during general anesthesia. Anesthesiology 1995; 82:832– 842 Marshall BE, Hanson CW, Frasch F, et al. Role of hypoxic pulmonary vasoconstriction in pulmonary gas exchange and blood flow distribution: 2. Pathophysiology. Intensive Care Med 1994; 20:379 –389

3488

Downloaded From: http://journal.publications.chestnet.org/pdfaccess.ashx?url=/data/journals/chest/22033/ on 01/17/2017

Clinical Investigations