The effectiveness of incentive spirometry with physical therapy for high-risk patients after coronary artery bypass surgery.Key Words: Atelectasis atelectasis or lung collapse Lack of expansion of pulmonary alveoli (see pulmonary alveolus). With a large-enough collapsed area, the victim stops breathing. , Coronary artery bypass Coronary artery bypass Surgical procedure to reroute blood around a blocked coronary artery. Mentioned in: Heart Failure coronary artery bypass, n , Pulmonary physical therapy, Spirometry Spirometry The measurement, by a form of gas meter, of volumes of gas that can be moved in or out of the lungs. The classical spirometer is a hollow cylinder (bell) closed at its top. . Pulmonary complications in the period immediately following coronary artery bypass grafting coronary artery bypass graft n. Abbr. CABG A surgical procedure in which a section of vein or other conduit is grafted between the aorta and a coronary artery below the region of an obstruction in that artery. (CABG CABG coronary artery bypass graft. CABG abbr. coronary artery bypass graft CABG Coronary artery bypass graft, see there ) are a cause of morbidity.[1] Patients with preexisting pre·ex·ist or pre-ex·ist v. pre·ex·ist·ed, pre·ex·ist·ing, pre·ex·ists v.tr. To exist before (something); precede: Dinosaurs preexisted humans. v.intr. pulmonary disease have been reported to be at increased risk for complications following surgery.[1-3] By contrast, Warner et al[4] reported no increased risk following CABG. The effectiveness of physical therapy when provided routinely for patients following CA13G has not been proven to be effective in decreasing morbidity.[5-7] Jenkins et al[7] concluded that the addition of breathing exercises or incentive spirometry incentive spirometry Pulmonology A form of spirometry which may prevent the complications–eg, atelectasis and infiltrates–of acute chest syndrome in sickle cell anemia. See Acute chest syndrome. (IS) to early ambulation am·bu·late intr.v. am·bu·lat·ed, am·bu·lat·ing, am·bu·lates To walk from place to place; move about. [Latin ambul , forced expiratory ex·pi·ra·to·ry adj. Of, relating to, or involving the expiration of air from the lungs. expiratory relating to or employed in the expiration of air from the lungs. maneuvers, and coughing conferred no additional benefits to their patient population, whose average preoperative pre·op·er·a·tive adj. Preceding a surgical operation. preoperative preceding an operation. preoperative care the preparation of a patient before operation. spirometric data indicated no airflow limitations. Stiller et al[5] also studied patients whose preoperative spirometric data indicated no air-flow limitations. They reported that preoperative education. postoperative deep breathing exercises, and forced expiration maneuvers were not effective in reducing morbidity. Johnson et al[6] did not provide sufficient spirometric data to allow determination of whether their patients had airflow limitations. They reported that for those patients with minimal atelectasis at the time of extubation, the addition of sustained maximal inflations (SMI (1) (Storage Management Initiative) The initiative developed by the SNIA in 2003 to create a single standard interface for storage management technologies used by multiple vendors and networking communities. ) to a routine of education, early ambulation, and deep breathing exercises did not reduce morbidity.[6] The outcomes of those patients with marked atelectasis at the time of extubation were not Improved by the addition of percussion to a regimen of ambulation, deep breathing exercises, and SMI.[6] Patients with preexisting pulmonary disease may have been included in these and other studies that evaluated the effectiveness of both IS and physical therapy, but their data were not analyzed separately. Smoking is a risk factor for the development of both coronary artery disease coronary artery disease, condition that results when the coronary arteries are narrowed or occluded, most commonly by atherosclerotic deposits of fibrous and fatty tissue. [8] and pulmonary diseases,[9] and many patients undergoing CABG demonstrate spirometric evidence of pulmonary disease. Incentive spirometry is used frequently as a component of postoperative pulmonary management. Studies evaluating the effectiveness of IS in patients who have had cardiac surgery, however, have been unable to demonstrate the superiority of IS over breathing exercises,[7,10] early mobilization,[7,10] or intermittent positive pressure breathing intermittent positive pressure breathing n. Abbr. IPPB See controlled mechanical ventilation. .[11-13] In contrast, Oulton et al[14] compared the use of physical therapy alone with the use of physical therapy and each of two incentive spirometers and found that the group using an device requiring a preset volume goal had superior results. The purpose of this study, therefore, was to investigate whether a combination of IS and physical therapy was more effective than physical therapy alone in decreasing postoperative complications postoperative complications, n.pl unexpected problems that arise following surgery. The most frequent are bleeding, infection, and protracted pain. in high-risk patients with chronic airflow limitation secondary to obstructive airways disease obstructive airways disease Any lung disease–asthma, COPD with airway obstruction, hyperresponsiveness Management Inhaled corticosteroids, maintenance therapy with a β2 who were undergoing CABG. Methods and Materials Subjects All patients who were scheduled for coronary artery bypass surgery Coronary artery bypass surgery, also coronary artery bypass graft surgery, and colloquially heart bypass or bypass surgery is a surgical procedure performed to relieve angina and reduce the risk of death from coronary artery disease. alone (not associated with valve replacements or other procedures) between November 1991 and December 1993 underwent preoperative spirometry screening. Forced expired volume in 1 second ([FEV FEV forced expiratory volume. FEV abbr. forced expiratory volume FEV forced expiratory volume. .sub.1]) and forced vital capacity forced vital capacity n. Abbr. FVC Vital capacity measured with subject exhaling as rapidly as possible. forced vital capacity, n a measure of the maximum rate of exhalation. (FVC FVC forced vital capacity. FVC abbr. forced vital capacity FVC, n See forced vital capacity. FVC forced vital capacity. ) were collected preoperatively. Patients who met the criteria for the study ([FEV.sub.1] of less than 70% of the predicted value, using prediction equations reported by Crapo et al,[15] and an [FEV.sub.1]/FVC ratio of less than 0.8) were asked to participate in the study, and written informed consent was obtained. Patients who developed hemodynamic he·mo·dy·nam·ics n. (used with a sing. verb) The study of the forces involved in the circulation of blood. he complications (eg, intraoperative myocardial infarction myocardial infarction: see under infarction. , major blood loss, marked hypotension hypotension or low blood pressure Condition in which blood pressure is abnormally low. It may result from reduced blood volume (e.g., from heavy bleeding or plasma loss after severe burns) or increased blood-vessel capacity (e.g., in syncope). , reduced cardiac output cardiac output n. Abbr. CO The volume of blood pumped from the right or left ventricle in one minute. It is equal to the stroke volume multiplied by the heart rate. requiring the use of an intra-aortic balloon pump intra-aortic balloon pump n. A pump connected to a balloon device that is inserted into the descending aorta to provide temporary assistance to the heart in the management of left ventricular failure. or extraordinary use of medications) in the operating room operating room n. Abbr. OR A room equipped for performing surgical operations. and those who were intubated longer than 72 hours following arrival in the cardiovascular intensive care unit (CV-ICU) were excluded. Procedure Eligible subjects received preoperative physical therapy, which included assessment of pulmonary status and associated risk factors and education about postoperative management. Postoperative physical therapy commenced on the first day in the CV-ICU. The therapist assessed the patients, and then assisted them in lung-expansion maneuvers (sustained maximal inspiratory in·spi·ra·to·ry adj. Of, relating to, or used for the drawing in of air. inspiratory pertaining to or used in the inspiration of air into the lungs. maneuvers and bed mobility) and secretion-removal maneuvers (supported/assisted coughing). This management was provided once or twice per day by the physical therapist, and encouraged by other members of the health care team in the CV-ICU (nurses and respiratory therapists). Chest wall vibrations and percussions and suctioning were also done, if required. The frequency and content of physical therapy treatments and the encouragement by other staff members were provided similarly to all subjects in the trial. Patients were treated by the physical therapist more than once per day if they had at least one of the following signs: radiological evidence of lobar lo·bar adj. Of or relating to a lobe or lobes. Lobar Relating to a lobe, a rounded projecting part of the lungs. Mentioned in: Congenital Lobar Emphysema lobar pertaining to a lobe. atelectasis, marked hypoxia hypoxia Condition in which tissues are starved of oxygen. The extreme is anoxia (absence of oxygen). There are four types: hypoxemic, from low blood oxygen content (e.g., in altitude sickness); anemic, from low blood oxygen-carrying capacity (e.g. , bilateral or extensive adventitious ADVENTITIOUS, adventitius. From advenio; what comes incidentally; us adventitia bona, goods that, fall to a man otherwise than by inheritance; or adventitia dos, a dowry or portion given by some other friend beside the parent. or bronchial bronchial /bron·chi·al/ (brong´ke-al) pertaining to or affecting one or more bronchi. bron·chi·al adj. Relating to the bronchi, the bronchial tubes, or the bronchioles. breath sounds, or production of large amounts of sputum sputum /spu·tum/ (spu´tum) [L.] expectoration; matter ejected from the trachea, bronchi, and lungs through the mouth. sputum cruen´tum bloody sputum. . After extubation, physical therapy management continued as described. Thoracic mobility and shoulder range-of-motion exercises commenced on the second postoperative day and were reinforced subsequently. As soon as possible, patients were assisted with ambulation (this was usually on the third postoperative day when the patients' cardiovascular status was stable). Physical therapy management also included education about self-monitoring and progression of activity. At the time of extubation, normally in the first 24 hours postoperatively, subjects were assigned randomly to one of two treatment protocols, using a computer-generated random number table. Researchers[16,17] have reported a greater effect on pulmonary function for patients for whom the internal mammary artery mammary artery n. The internal thoracic artery or the lateral thoracic artery. Mammary artery A chest wall artery that descends from the aorta and is commonly used for bypass grafts. was used for the bypass when compared with saphenous vein saphenous vein n. Either of two main superficial veins of the leg, one larger than the other, that begin at the foot. Saphenous vein A long vein in the thigh or calf commonly used for bypass grafts. conduit. To ensure that subjects receiving the mammary artery conduits were equally distributed between the two treatment groups, separate randomization randomization (ranˈ·d  ·m tables were
used (prognostic stratification).Group 1. Subjects who were randomly assigned to this group received only the postoperative physical therapy described. Group 2. Subjects who were randomly assigned to this group received the physical therapy management described, and they were provided with an incentive spirometer(*) on the day of extubation, with directions for its use. This device is volume oriented, with a flow-monitoring component to encourage a sustained maximal inspiration. Nursing, respiratory therapy respiratory therapy Medical profession concerned with assisting the respiratory function of individuals who have severe lung disorders. Practices include suctioning to clear secretions from the airway, use of aerosol mists (sometimes medicated) or gases to ease breathing, , and physical therapy staff were instructed to remind all subjects in group 2 to use the device hourly, but spirometer spirometer /spi·rom·e·ter/ (spi-rom´e-ter) an instrument for measuring the air taken into and exhaled by the lungs. spi·rom·e·ter n. used was not successfully measured. Measurements The primary outcome measure chosen was atelectasis as estimated by chest radiography. Table 1 details the measurement schedule. Atelectasis, or collapse of the expanded lung, was evaluated using the scale shown in Table 2, which was based on previously described pulmonary radiographic radiographic (rā´dēōgraf´ik), adj relating to the process of radiography, the finished product, or its use. evaluation methodology.[7] These measurements were read and categorized by a single observer, who was blind to the treatment allocation of the patient. This observer also noted the presence or absence of pulmonary edema Pulmonary Edema Definition Pulmonary edema is a condition in which fluid accumulates in the lungs, usually because the heart's left ventricle does not pump adequately. , pneumothorax pneumothorax (n  mōthôr`ăks), collapse of a lung with escape of air into the pleural cavity between the lung and the chest wall. The cause may be traumatic (e.g. , and pleural
effusion Pleural Effusion DefinitionPleural effusion occurs when too much fluid collects in the pleural space (the space between the two layers of the pleura). It is commonly known as "water on the lungs. , because all of these sequelae sequelae Clinical medicine The consequences of a particular condition or therapeutic intervention can influence pulmonary function. Table 1. Measurement Schedule Measure(a) Preoperative Extubation Day 2 Day 3 Chest radiograph AP X X X X PA X Lateral X [FEV.sub.1], FVC X X X X Oxygen saturation X X X X Measure(a) Discharge Chest radiograph AP PA X Lateral X [FEV.sub.1], FVC X Oxygen saturation X (a) AP = anteroposterior anteroposterior /an·tero·pos·te·ri·or/ (-pos-ter´e-er) directed from the front toward the back. an·ter·o·pos·te·ri·or adj. Abbr. AP 1. Relating to both front and back. , PA = posteroanterior, [FEV.sub.1]=forced expired volume in 1 second, FVC = forced vital capacity. Table 2. Chest Radiograph Analysis Scale Finding 0 Clear or minor collapse, either unilaterally or bilaterally 1 Major collapse, either unilaterally or bilaterally Yes/no Pleural effusion Yes/no Pneumothorax Yes/no Pulmonary edema Secondary outcome measures included estimation of lung infection, oxygen saturation oxygen saturation sO2 The O2 concentration of blood expressed as a ratio of its total O2-carrying capacity; the OS is a measure of the utilization of O2 transport capacity; sO2 , and number of postoperative days in the hospital. Lung infection was determined to be present if there was a temperature at or above 38.5 [degrees] C (using an Ivac tympanic tympanic /tym·pan·ic/ (tim-pan´ik) 1. tympanal; of or pertaining to the tympanum. 2. bell-like; resonant. tym·pan·ic adj. 1. technique), after the day of surgery, associated with a positive sputum culture Sputum Culture Definition Sputum is material coughed up from the lungs and expectorated (spit out) through the mouth. A sputum culture is done to find and identify the microorganism causing an infection of the lower respiratory tract such as pneumonia . Increased temperature alone has not been demonstrated to be a reliable indicator of postoperative pulmonary complications.[18] Oxygen saturation was estimated noninvasively, using a pulse oximeter pulse oximeter n. A device, usually attached to the earlobe or fingertip, that measures the oxygen saturation of arterial blood. pulse oximetry n. .([dagger]) In the early postoperative phase, if the patient was using added oxygen, the pulse oximeter was removed for 15 minutes prior to assessment of oxygen saturation. If the patient desaturated below 88% while breathing room air, oxygen saturation was not measured. Pulse oximetry pulse oximetry Oxygen saturation measurement, SaO Critical care A method used to determine the O2 saturation–SaO2 and desaturation of blood in a continuous noninvasive fashion, through the noninvasive assessment of arterial Hb-bound measurements have been found to correlate well with direct measurements of arterial oxygenation oxygenation /ox·y·gen·a·tion/ (ok?si-je-na´shun) 1. the act or process of adding oxygen. 2. the result of having oxygen added. when saturations are above 80% (r=.878-.981).[19] Pulse oximeters consistently underestimate true saturation by 2.0% to 2.8%.[19] Nickerson et al[20] reported that changes of 1% in the saturation range above 90% and 2% in the range below 90% are indicative of clinical change.[20] The number of postoperative days in the hospital were extracted from each patient's hospital record, counting the day following surgery as the first postoperative day. Lung volumes lung volumes Physiology A group of air 'compartments' into which the lung may be functionally divided Lung volumes Expiratory reserve capacity–ERV The maximum volume of air that can be voluntarily exhaled ([FEV.sub.1], FVC) were also measured for the 3 days following extubation and prior to discharge because patients with radiologic evidence of atelectasis frequently have decreased lung volumes.[21] Spirometric measurements were taken with a portable spirometer,([double dagger]) with the patient seated or lying at a 45-degree incline, using standardized instructions. The best [FEV.sub.1] and FVC of three trials were recorded, not necessarily from the same trial. Forced expired volume in 1 second and FVC are among the most reliable of spirometric measures, with coefficients of variation of between 1.95% and 4.5% in asymptomatic individuals and slightly greater when associated with pathology.[20] Measurements obtained with pocket spirometers have been found to correlate highly with those obtained with the Vitalograph [sub sections] (r=.981 for FVC, r=.9491 for [FEV.sub.1]).[22] When measuring [FEV.sub.1], the pocket spirometer underestimates the volume by 201 mL, when compared with the Vitalograph, the standard bellows type of spirometer used to measure these lung volumes.[22] Data Analysis Characteristics of the two groups at baseline were compared using unpaired two-tailed Student's t tests (age, [FEV.sub.1], [FEV.sub.1] /FVC ratio, smoking pack-years) and chi-square tests (gender, use of internal mammary mammary /mam·ma·ry/ (mam´ah-re) pertaining to the mammary gland, or breast. mam·ma·ry adj. Of or relating to a breast or mamma. mammary pertaining to the mammary gland. conduit, number of vessels bypassed, number of patients undergoing redo To reverse an undo operation. See undo. procedure, current smokers, current use of bronchodilators Bronchodilators Definition Bronchodilators are medicines that help open the bronchial tubes (airways) of the lungs, allowing more air to flow through them. ). Postoperative atelectasis in the two groups was analyzed for each day of measurement, using chi-square tests. Radiologic evidence of pleural effusion, pneumothorax, and pulmonary edema was analyzed using a two-tailed Fisher's Exact chi-square test, as were incidence of postoperative infection and oxygen saturation. Student's t tests were used to compare days in the hospital.[23] A Mantel-Haenszel chi-square test was done to test the overall treatment effect.[24] A Breslow-Day test for homogeneity was performed to determine whether the treatment effect was similar between subjects with and without atelectasis at extubation. Subjects were stratified stratified /strat·i·fied/ (strat´i-fid) formed or arranged in layers. strat·i·fied adj. Arranged in the form of layers or strata. based on the presence or absence of pronounced atelectasis at the time of extubation. Two-by-two tables of treatment versus outcome were constructed for each subgroup. The Mantel-Haenszel procedure was used to test the average (summary) odds ratio over the two subgroups. The associated test of homogeneity of odds ratio over strata yielded the formal comparison of whether the treatment effect varied between strata. Risk reduction is computed as 1 minus the odds ratio. This is a measure of odds-ratio reduction or relative risk. A probability value of .05 was considered to be the limit of significance for all analyses. Results Nine hundred ninety-nine subjects who had CABG were screened for the study. The mean [FEV.sub.1] /FVC ratio was 75.96 (SD=9.8, range= 18-96), and the mean [FEV.sub.1] measured/[FEV.sub.1] predicted ratio was 80.3 (SD=17.8, range=13-133). One hundred ninety-nine subjects (19.9% of those screened) met the entry criteria for the study. One hundred eighty-five subjects entered the trial (for details of enrollment, see Tab. 3). Randomization was successful in that the two treatment groups were matched on all characteristics, and there were no differences on any of these factors (Tab. 4). One hundred fifty-three subjects had [FEV.sub.1]/FVC ratios of less than 0.75, which is indicative of a greater degree of airflow limitation, and they were equally distributed between the two groups. Table 3. Preoperative Screening for Eligibility and Reasons for Nonentry
No. of
Patients
Underwent screening for eligibility 999
Did not meet spirometry criteria 800
Met spirometry entry criteria 199
Refused consent 2
Intraoperative complications 3
Marked bronchospasm, unable to do spirometry 1
Intubated [is greater than] 72 h 6
Randomly assigned to receive only physical therapy,
given incentive spirometry by staff 2
Total eligible but not assigned to groups 14
Total eligible and randomly assigned to groups 185
Table 4.
Preoperative Profiles of Study Patients(a)
Variable PT Only IS+PT
Age (y)
X 64.8 64.0
SD 8.6 8.9
Range 42-83 38-78
Gender
Male (%) 79 (83%) 74 (82%)
[FEV.sub.1] (L)
X 1.8 1.9
SD 0.5 0.5
Range 0.49-2.68 0.71-2.8
[FEV.sub.1]/FVC ratio
X 0.68 0.65
Range 0.18-0.79 0.43-0.73
Vessels bypassed
X 2.9 2.8
SD 0.8 0.9
Range 1-5 1-5
Conduit
Internal mammary artery (%) 61 (64%) 58 (64%)
CABG: initial/redo
Initial (%) 91 (96%) 85 (94%)
Smoking at time of surgery
Yes (%) 9 (10%) 9 (10%)
Pack-years
X 30.6 31.0
SD 23 26
Range 0-84 0-80
Preoperative use of bronchodilators
Yes (%) 21 (22%) 15 (17%)
Variable Test/Significance
Age (y)
X t test/P=.54
SD
Range
Gender
Male (%) [chi square]/P=.87
[FEV.sub.1] (L)
X t test/P=.38
SD
Range
[FEV.sub.1]/FVC ratio
X t test/P=.057
Range
Vessels bypassed
X t test/P=.76
SD
Range
Conduit
Internal mammary artery (%) [chi square]/p=.97
CABG: initial/redo
Initial (%) [chi square]/p=.67
Smoking at time of surgery
Yes (%) [chi square]/p=1.00
Pack-years
X t test/P= .91
SD
Range
Preoperative use of bronchodilators
Yes (%) [chi square]/p= .40
(a) [FEV.sub.1] = forced expired volume in 1 second, FVC = forced vital capacity, CABG = coronary artery bypass grafting, PT = physical therapy, IS = incentive spirometry. Table 5 shows the numbers and percentages of subjects in each treatment group with marked collapse or consolidation. A major degree of atelectasis is defined as unilateral lobar or bilateral segmental lung collapse lung collapse Pneumothorax, see there. See Atelectasis. . There was no difference between the groups. Figure 1 depicts the incidence of atelectasis graphically. Slightly more subjects in group 2 had pronounced collapse or consolidation at the time of extubation (14.8% versus 9.5% in group 1), but this difference was not statistically significant. [Figure 1 ILLUSTRATION OMITTED] Table 5. Incidence of Atelectasis (Unilateral ar Bilateral) Measured Radiographically(a)
PT Only IS+PT
Significance(b)
(n=95) (n=90)
Preoperative 1/95 (1.0%) 0/90 (0%) ...(c)
Extubation(*) 9/95 (9.5%) 13/88 (14.8%) P=.36
Day 2(*) 19/91 (20.9%) 15/84 (17.9%) P=.73
Day 3(*) 11/49 (22.5%) 16/49 132.7%) P=.25
Discharge(*) 10/95 (10.5%) 9/89 (10.1 %) P=.97
(a) Asterisk (*) indicates some missing data. Radiographs not always available for each subject daily. PT = physical therapy, IS = incentive spirometry. (b) Significance based on chi-square test. (c) Not significant; unable to calculate because of "0" in one cell and "1" in another cell. Pleural effusion (diagnosed radiologically) was a common finding postoperatively (Tab. 6). Pneumothorax and pulmonary edema (evident radiologically) were less common (Tab. 6). There were no differences between the two treatment groups on any of these findings at any time. Table 6. Numbers of Subjects With Radiographic Evidence of Pleural Effusion, Pneumothorax, and Pulmonary Edema(a)
Extubation Day 2 Day
3
PT PT PT
Only IS+PT Only IS+PT Only
(n=95) (n=88) (n=91) (n=84)
(n=49)
Pleural effusion 17 18 31 25 24
Pneumothorax 2 3 2 1 2
Pulmonary edema 2 3 2 2 0
Discharge
PT
IS+PT Only IS+PT
(n=49) (n=95) (n=89)
Pleural effusion 19 38 37
Pneumothorax 1 0 1
Pulmonary edema 3 3 4
(a) PT = physical therapy, IS= incentive spirometry.
Secondary outcomes included number of postoperative days in hospital, incidence of infection, spirometry ([FEV.sub.1], FVC), and oxygen saturation. There was no difference between the two treatment groups on any of these outcomes (Tabs. 7 and 8, Figs. 2 and 3). [Figures 2-3 ILLUSTRATION OMITTED]
Table 7.
Postoperative Morbidity of Study Patients(a)
Outcome PT Only IS+PT Test/Significance
Postoperative days in
hospital
X 9.7 9.0 t test/P=.22
SD 4.9 3.1
Range 6-45 5-25
No. of patients with
postoperative
infection (%) 10 (10.5%) 8 (8.9%) [chi square]/P=.71
(a) PT = physical therapy, IS = incentive spirometry.
Table 8. Oxygen Saturation (Measured by Pulse Oximetry), Identifying the Number of Subjects. With Saturation of Less Than 88% Without Supplemental Oxygen(a)
PT Only IS+PT Test/Significance
Preoperative 0/89 0/84 ...(b)
Extubation 51/83 45/87 [chi square]/p=.45
Day 2 42/87 33/86 [chi square]/p=.19
Day 3 21/86 17/85 [chi square]/p=.25
Discharge 0/90 0/79 ...(b)
(a) PT = physical therapy, IS = incentive spirometry. (b) Unable to calculate because of "0" in at least one cell. We assumed that subjects with marked atelectasis at the time of extubation may benefit to a greater degree from the intervention. In addition, there were slightly more subjects with pronounced atelectasis in group 2. A stratified analysis, therefore, was undertaken. Figures 4 and 5 differentiate between those subjects who, at the time of extubation and randomization, had little evidence of atelectasis and those with pronounced evidence of atelectasis. Two patients did not undergo chest radiography on the day of extubation and thus could not included in this analysis. In the 161 patients with minimal atelectasis at extubation, there was no benefit on day 2, as demonstrated by the addition of IS (Fig. 4). Very few of these subjects had atelectasis on the next day, and there was no difference between the two treatment groups. Among the 22 subjects with clinically important atelectasis on extubation, there was a risk reduction of 28% in group 2 by the next day (Fig. 5). For the subjects in group 2, there was a 22% risk reduction by the third day following extubation and a 54% risk reduction by the time of discharge. The test for homogeneity was not significant, indicating that the relative risk was not statistically significant, despite the trend. There was no association between those 22 subjects with marked atelectasis at extubation and those with an [FEV.sub.1] /FVC ratio of less than 0.6, which indicates a greater degree of chronic airflow limitation secondary to obstructive lung disease lung disease Pulmonary disease Pulmonology Any condition causing or indicating impaired lung function Types of LD Obstructive lung disease–↓ in air flow caused by a narrowing or blockage of airways–eg, asthma, emphysema, chronic bronchitis; . [Figures 4-5 ILLUSTRATION OMITTED] Discussion Maximal inflations of the lung increase production of surfactant Surfactant Definition Surfactant is a complex naturally occurring substance made of six lipids (fats) and four proteins that is produced in the lungs. It can also be manufactured synthetically. , improve compliance and oxygenation,[25,26] and may assist in reexpansion of areas of atelectasis.[27] Clinical trials evaluating the management of postoperative complications have been plagued by small sample sizes, a lack statistical power to demonstrate a treatment effect, no consensus as to what constitutes a complication, and inadequate descriptions of the treatment. Trials that have failed to document the efficacy of routine postoperative physical therapy treatments have not included power calculations, which would enable the reader to detect a Type II error.[5-7] Despite the lack of evidence, usage of IS for prophylaxis of atelectasis remains common and varies widely, between 44% in the United Kingdom and 95% in the United States.[28,29] Incentive spirometry is provided in combination with physical therapy in the United Kingdom, whereas its combination with physical therapy is less frequent in the United States.[28,29] The incentive spirometer used in our study cost $7.25, and if proven to be as effective as physical therapy, would be an economic alternative. The results of our study indicate that the use of incentive spirometers in addition to physical therapy is not cost-effective. In our study, the only difference between the two treatment conditions was the addition of the visual biofeedback device biofeedback device Any instrument that measures physiologic parameters eg electromyographic activity, galvanic–electrodermal skin resistance, muscle tension, BP, and others; some mainstream physicians believe BDs may be used to control tachycardia, HTN, fecal (incentive spirometer), which was designed to enhance patient compliance. One explanation for the lack of difference in outcomes may be that subjects assigned to use the incentive spirometer did not comply. Our attempts to document patient compliance with the use of the incentive spirometer were not successful. All subjects in group 2 were provided with a form on which they and staff in the CV-ICU were asked to record use of the device each hour. Only 15 of the 90 subjects who were randomly assigned to receive the IS treatment documented any use. Subjects may have used the device as taught and failed to document utilization, or they may have used the device only minimally. Our study was designed to duplicate clinical practice, in which the patient is reminded by staff in the critical care unit to use the incentive spirometer as a visual cue to take maximal inspirations. Our primary outcome was radiographic evidence of atelectasis on the second postoperative day, at which time the radiographs of 95% of the subjects were available. We included the data and analysis from subsequent days because they support the findings, but we realize that the evidence is not as strong. Radiographs were available for only 58% of subjects on the third postoperative day, although they were obtainable for 99.5% of the subjects by the time of discharge. A control group with subjects receiving no postoperative physical therapy was not available, because such a protocol for patients considered to be at high risk would not have been approved by our institutional review board. The lack of differences in outcome between the two treatment groups (and especially in those subjects without marked atelectasis at extubation) may have been masked by the fact that the two treatments were not sufficiently different. This lack of differences in outcome could have been exacerbated by the apparent lack of compliance with use of the incentive spirometer. Our study replicates previous studies in which the use of IS combined with postoperative pulmonary physical therapy was compared with the use of physical therapy alone in a population undergoing CABG. In contrast to previous studies, however, the inclusion criteria for our study included an [FEV.sub.1]/FVC ratio of less than 0.8 and a measured [FEV.sub.1] of less than 70% of the predicted value. We were unable to find any benefit of IS combined with physical therapy over physical therapy alone in the management of these patients. Subjects who demonstrated preoperatively a more marked chronic airflow limitation were not more likely to develop marked atelectasis postoperatively. The use of radiological evidence as a primary outcome has been used in many trials.[7,30] There is no standardized method of radiographic analysis, but in our study all radiographs were evaluated by one of the researchers, who is both a pulmonologist pul·mo·nol·o·gist n. A physician who specializes in the diagnosis and treatment of respiratory disorders. and an intensivist (board-certified in surgery, internal medicine, or anesthesia, with additional training in managing patients in intensive care). In our study, the incidence of pronounced atelectasis, either unilateral or bilateral, was measured because both can be of clinical significance. If a true treatment effect reduces the rate of atelectasis by 50% (from the 21% in group 1), this study had a 47% power to detect this difference. Our study, therefore, may be considered slightly underpowered to detect a reasonable clinical effect. The stratified analysis of those 22 patients with marked collapse at extubation showed a trend toward an added benefit of IS, with risk reductions above 22%, when compared with the analysis of those patients who received only physical therapy. This trend, however, failed to reach statistical significance and was not associated with poorer preoperative spirometry. This failure to reach statistical significance may have been due to the small number of subjects (n=22) with marked atelectasis at the time of extubation. The incidence of marked atelectasis was 10.8% overall, which was higher than the incidence of 5.7% with segmental lobe collapse reported by Warner et al.[31] The overall rate of pulmonary infection was 9.7%, between the overall rate of 2.6% reported by Warner et al[31] and the overall rate of 20% reported by Johnson et al.[6] Both the incidence of marked atelectasis and the overall rate of pulmonary infection may have been associated with the degree of chronic airflow limitation and smoking history of our subjects. Conclusions In order for incentive spirometers to be effective, they must be used regularly (four to five sustained maximal inspirations during each hour that the patient is awake).[30] An observation made by the physical therapists involved in this study was that the incentive spirometer was often placed out of the patient's reach and sight. Adherence to usage appears to be an issue. If further study sanctions the effectiveness of IS in some patient populations, a counter or alarm could be added to encourage adherence. The results of our study add to the existing body of knowledge indicating that for the majority of patients with airflow limitation who undergo a CABG procedure, the addition of IS to physical therapy is not justified. The analysis indicates that for the small percentage of subjects (approximately 12% in this study) who exhibit marked atelectasis radiographically at the time of extubation, there may be an added benefit by the addition of IS to postoperative pulmonary physical therapy. Further study with a sufficient number of subjects is needed to establish whether the trend noted in our study is significant. Acknowledgments We thank the physical therapists who carried out the intervention and the respiratory therapists who collected the data, all of whom were from the General Division, Hamilton Civic Hospitals. (*) Voludyne 5000 spirometer, Sherwood Medical Co, 1915 Olive St, St Louis, MO 63103. ([dagger]) Model 8500, Nonin Medical, 12900 Highway 55, Plymouth, MN 55441. ([double dagger]) Roxon Pocket Spirometer, Micro Medical Ltd, PO Box 6, Rochester, Kent, United Kingdom ME1 2AZ. ([sub sections]) Vitalograph Ltd, 8347 Quivera Rd, Lenexa, KS 66215. References [1] Brooks-Brunn JA. Postoperative atelectasis and pneumonia. Heart Lung. 1995;24:94-115. [2] Dales RE, Dionne G, Leech JA, et al. Preoperative prediction of pulmonary complications following thoracic surgery Thoracic Surgery Definition Thoracic surgery is the repair of organs located in the thorax, or chest. The thoracic cavity lies between the neck and the diaphragm, and contains the heart and lungs (cardiopulmonary system), the esophagus, trachea, pleura, . Chest. 1993;104:155-159. [3] Gass GD, Olsen GN. Preoperative pulmonary function testing to predict postoperative morbidity and mortality Morbidity and Mortality can refer to:
[4] Warner MA, Tinker JH, Frye RL, et al. Risk of cardiac operations in patients with concomitant pulmonary dysfunction. Anesthesiology. 1982; 67:A57. Abstract. [5] Stiller K, Montarello J, Wallace M, et al. Efficacy of breathing and coughing exercises in the prevention of pulmonary complications after coronary artery coronary artery n. 1. An artery with origin in the right aortic sinus; with distribution to the right side of the heart in the coronary sulcus, and with branches to the right atrium and ventricle, including the atrioventricular branches and surgery. Chest. 1994;105:741-747. [6] Johnson D, Kelm C, To T, et al. Postoperative physiotherapy after coronary artery bypass surgery. Am J Respir Crit Care Med. 1995;152:953-958. [7] Jenkins SC, Soutar SA, Loukota JM, et al. Physiotherapy after coronary artery surgery: Are breathing exercises necessary? Thorax thorax, body division found in certain animals. In humans and other mammals it lies between the neck and abdomen and is also called the chest. The skeletal frame of the thorax is formed by the sternum (breastbone) and ribs in front and the dorsal vertebrae in back. . 1989;44:634-639. [8] Kannel WB. Update on the role of cigarette smoking in coronary artery disease. Am Heart J. 1981;101:319-328. [9] Habib MP, Burrows B. Chronic airways obstruction: the importance of certain risk factors for its development. Current Pulmonology pul·mo·nol·o·gy n. The branch of medicine that deals with diseases of the respiratory system. pulmonology The study of the lungs and respiratory function . 1990;2:247-272. [10] Dull JL, Dull WL. Are maximal inspiratory breathing exercises or incentive spirometry better than early mobilization after cardiopulmonary bypass cardiopulmonary bypass n. A procedure to circulate and oxygenate the blood during heart surgery involving the diversion of blood from the heart and lungs through a heart-lung machine and the return of oxygenated blood to the aorta. ? Phys Ther. 1983;63:655-659. [11] Gale GD, Sanders DE. incentive spirometry: its value after cardiac surgery. Canadian Anaesthetists' Society Journal. 1980;27:475-480. [12] 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. [13] Iverson LIG lig Brit slang Noun (esp. in the media) a function with free entertainment and refreshments Verb [ligging, ligged] to attend such a function ligger , Ecker RR, Fox HE, May IA. A comparative study of IPPB IPPB intermittent positive pressure breathing. IPPB abbr. intermittent positive pressure breathing IPPB intermittent positive-pressure breathing. , the incentive spirometer, and blow bottles: the prevention of atelectasis following cardiac surgery. Ann Thorac Surg. 1978;25:197-200. [14] Oulton JL, Hobbs GM, Hicken P. Incentive breathing devices and chest physiotherapy: a controlled trial controlled trial Clinical research A clinical study in which one group of participants receives an experimental drug while the other receives either a placebo or an approved–'gold standard' therapy. See Blinding, Double-blinded. . Can J Surg. 1981;24:638-640. [15] Crapo RO, Morris AH, Gardner RM. Reference spirometric values using techniques and equipment that meet ATS recommendations. Am Rev Respir Dis. 1981;123:659-664. [16] Berrizbeita LD, Tessler S, Jacobowitz IJ, et al. Effect of sternotomy and coronary bypass surgery Coronary bypass surgery A surgical procedure which places a shunt to allow blood to travel from the aorta to a branch of the coronary artery at a point past an obstruction. Mentioned in: Cardiac Catheterization, Thallium Heart Scan on postoperative pulmonary mechanics: comparison of internal mammary and saphenous vein bypass grafts. Chest. 1989;96:873-876. [17] Fernande PG, Beets G, Michels A et al. Pulmonary function tests after different techniques for coronary artery bypass surgery. Intensive Care Med. 1988;14:623-627. [18] Roberts J, Barnes W, Pennock M, Browne G. Diagnostic accuracy of fever as a measure of pulmonary complications. Heart Lung 1988;17:166-169. [19] Taylor MB, Whitwam JG. The accuracy of pulse oximeters. Anesthesiology. 1988;43:229-232. [20] Nickerson BG, Sarkson C, Tremper K. Bias and precision of pulse oximeters and arterial oximeters. Chest. 1988;93:515-517. [21] Peng MJ, Vargas FS, Cukier A, et al. Postoperative pleural Pleural Pleural refers to the pleura or membrane that enfolds the lungs. Mentioned in: Pneumothorax pleural emanating from or pertaining to the pleura. changes after coronary artery revascularization: comparison between saphenous vein and internal mammary artery grafting. Chest. 1992;101:327-330. [22] Hosie HE, Nimmo WS. Measurement of [FEV.sub.1] and FVC. Anesthesiology. 1988;43:233-238. [23] Norman GR, Streiner DL. PDQ (Parallel Data Query) A query optimized for massively parallel processors (MPPs). The software breaks down the query into pieces so that several parts of the database can be searched simultaneously. See SMP. Statistics. Toronto, Ontario, Canada: BC Decker; 1986:41-45, 103-105. [24] Fleiss JL. Statistical Methods for Rates and Proportions. New York New York, state, United States New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of , NY: John Wiley & Sons Inc; 1981: chap 10. [25] Williams JV, Tierney DF, Parker HR. Surface forces in the lung, atelectasis, and transpulmonary pressure transpulmonary pressure Physiology The difference between airway pressure and pleural pressure–PAW—PPL, a clinically important respiratory measure in ICU Pts; it is also derived by multiplying the airway pressure by the ratio of . J Appl Physiol. 1960;21:819-827. [26] Zikria BA, Spencer JL, Michailoff T, et al. Breathing patterns in preoperative, postoperative and critically ill patients. Surgical Forum. 1971;22:40-41. [27] Menkes HA, Traystman RJ. Collateral ventilation. Am Rev Respir Dis. 1977;116:287-309. [28] Jenkins SC, Soutar SA. A survey into the use of incentive spirometry following coronary artery bypass graft surgery Coronary Artery Bypass Graft Surgery Definition Coronary artery bypass graft surgery is a surgical procedure in which one or more blocked coronary arteries are bypassed by a blood vessel graft to restore normal blood flow to the heart. . Physiotherapy. 1986;72:492-493. [29] O'Donohue WJ. National survey of the usage of lung expansion modalities for the prevention and treatment of postoperative atelectasis following abdominal and thoracic surgery. Chest. 1985;87:76-80. [30] Craven JL, Evans GA, Davenport PJ, Williams RHP rhp abbr. rated horsepower . The evaluation of the incentive spirometer in the management of postoperative pulmonary complications. Br J Surg. 1974;61:793-797. [31] Warner MA, Offord KP, Warner ME, et al. Role of preoperative cessation and other factors in postoperative pulmonary complications: a blinded study of coronary artery bypass patients. Mayo Clin Proc. 1989;64:609-616. JM Crowe, MHSc, PT, is Assistant Clinical Professor, School of Rehabilitation Science, McMaster University, Bldg T17, 1280 Main St W, Hamilton, Ontario, Canada LOS 4K1 (crowe@fhs.mcmaster.ca), and Research Therapist, Department of Rehabilitation Services, General Division, Hamilton Civic Hospitals. Address all correspondence to Ms Crowe at the first address. CA Bradley, MD, FRCP FRCP Fellow of the Royal College of Physicians. FRCP abbr. Fellow of the Royal College of Physicians (C), is Assistant Clinical Professor, Department of Medicine, McMaster University, and Departments of Internal Medicine and Critical Care, General Division, Hamilton Civic Hospitals. This study was approved by the Institutional Review Board of Hamilton Civic Hospitals. Portions of this research were presented at the American Physical Therapy Association/Canadian Physiotherapy Association Joint Congress in Toronto, Ontario, Canada, in dune 1994, and at the Royal College of Physicians and Surgeons of Canada The Royal College of Physicians and Surgeons of Canada, (RCPSC) is a national, private, nonprofit organization established in 1929 by a special Act of Parliament to oversee the medical education of specialists in Canada. meeting in Montreal, Ontario, Canada, in September 1995. |
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