Atelectasis is a common problem in post-operative patients and those with neuromuscular or chest wall disease. Because atelectasis in some patients appears to be due to repeated small inspirations, deeper breaths may be helpful. Incentive spirometers encourage expansion of the lungs as much as possible above spontaneous breathing; these have proved to be beneficial in controlled studies.
The use of intermittent positive pressure breathing (IPPB) has been declining because the benefit has been difficult to demonstrate in most patients. Although sometimes used to deliver bronchodilator medications, IPPB is usually intended to prevent or treat atelectasis. In objective studies, patients can improve atelectasis if and only if IPPB can increase the depth of breathing more than the patient alone can achieve. Intermittent positive pressure breathing can be tried in patients with respiratory muscle weakness due to neuromuscular disease, those with chest wall abnormalities, and after abdominal surgery. In general, the literature suggests that incentive spirometry should be tried first and IPPB used only when there is proof that larger inspired volumes can be reached with this technique. Intermittent positive pressure breathing is contraindicated in persons with untreated tension pneumothorax.
In a systematic review, Pasquina et al (2003) examined if respiratory physiotherapy, including IPPB, prevented pulmonary complications after cardiac surgery. The authors concluded that the usefulness of respiratory physiotherapy for the prevention of pulmonary complications after cardiac surgery remains unproved. Large randomized studies are needed with no intervention controls, clinically relevant end points, and reasonable follow-up periods. Indeed, the American Association for Respiratory Care (AARC)'s clinical practice guideline on IPPB (Sorenson et al, 2003) did not list prophylactic respiratory physiotherapy following cardiac surgery as a recommended indication for IPPB.
Pasquina and colleagues (2006) examined the efficacy of respiratory physiotherapy for prevention of pulmonary complications after abdominal surgery. These investigators searched in databases and bibliographies for articles in all languages through November 2005. Randomized trials were included if they investigated prophylactic respiratory physiotherapy and pulmonary outcomes, and if the follow-up was at least 2 days. Efficacy data were expressed as risk differences (RDs) and number needed to treat (NNT), with 95 % confidence intervals (CIs); 35 trials tested respiratory physiotherapy treatments. Of 13 trials with a "no intervention" control group, 9 studies (n = 883) did not report on significant differences, and 4 studies (n = 528) did: in 1 study, the incidence of pneumonia was decreased from 37.3 to 13.7 % with deep breathing, directed cough, and postural drainage (RD, 23.6 %; 95 % CI: 7 % to 40 %; NNT, 4.3; 95 % CI: 2.5 to 14); in 1 study, the incidence of atelectasis was decreased from 39 % to 15 % with deep breathing and directed cough (RD, 24 %; 95 % CI: 5 % to 43 %; NNT, 4.2; 95 % CI: 2.4 to 18); in 1 study, the incidence of atelectasis was decreased from 77 % to 59 % with deep breathing, directed cough, and postural drainage (RD, 18 %; 95 % CI: 5 % to 31 %; NNT, 5.6; 95 % CI: 3.3 to 19); in 1 study, the incidence of unspecified pulmonary complications was decreased from 47.7 % to 21.4 - 22.2 % with IPPB, or incentive spirometry, or deep breathing with directed cough (RD, 25.5 % to 26.3 %; NNT, 3.8 to 3.9). A total of 22 trials (n = 2,734) compared physiotherapy treatments without no intervention control subjects; no conclusions could be drawn. The authors concluded that there are only a few trials that support the usefulness of prophylactic respiratory physiotherapy. The routine use of respiratory physiotherapy after abdominal surgery does not seem to be justified.
In an unblinded, randomized cross-over study, Laffont et al (2008) examined if IPPB improved lung compliance, work of breathing, and respiratory function in patients with recent high spinal cord injury (SCI). A total of 14 patients with SCI caused by trauma within the last 6 months and located between C5 and T6 were included in the study. Two months of IPPB and 2 months of conventional treatment were evaluated prospectively in random order in patients with SCI. Non-invasive lung function tests and arterial blood gas measurements were obtained repeatedly in all patients. Repeated measurements of dynamic lung compliance and work of breathing as measured by computing the area enclosed between the inspiratory esophageal pressure-tidal volume curve, and the theoretical chest wall static pressure-volume curve were performed in 7 patients. Intermittent positive pressure breathing had no long-term effects on vital capacity (52.1 % +/- 11.3 % versus 54.5 % +/- 12.5 %, after conventional treatment and IPPB, respectively; p = 0.27), lung compliance (66.4 +/- 48.9 ml/cmH(2)O versus 70.3 +/- 38.4 ml/cmH(2)O; p = 0.56), or other lung function tests. Intermittent positive pressure breathing did not exert short-term effects on lung compliance or work of breathing. The authors concluded that IPPB produced no immediate or long-term improvements in lung function or ventilatory mechanics in patients with recent SCI.
In a Cochrane review, Guimaraes and colleagues (2009) evaluated the effects of incentive spirometry (IS) compared to no such therapy (or other therapy) on all-cause post-operative pulmonary complications (atelectasis, acute respiratory inadequacy) and mortality in adult patients admitted for upper abdominal surgery. These investigators searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 3), MEDLINE, EMBASE, and LILACS (from inception to July 2006). They included randomized controlled trials of IS in adult patients admitted for any type of upper abdominal surgery, including patients undergoing laparoscopic procedures. Two authors independently assessed trial quality and extracted data. These researchers included 11 studies with a total of 1,754 subjects. Many trials were of only moderate methodological quality and did not report on compliance with the prescribed therapy. Data from only 1,160 patients could be included in the meta-analysis. Three trials (n = 120) compared the effects of IS with no respiratory treatment; 2 trials (n = 194) compared IS with deep breathing exercises; 2 trials (n = 946) compared IS with other chest physiotherapy. All showed no evidence of a statistically significant effect of IS. There was no evidence that IS is effective in the prevention of pulmonary complications. The authors concluded that there is no evidence regarding the effectiveness of the use of IS for the prevention of post-operative pulmonary complications in upper abdominal surgery. They noted that this review underlines the urgent need to conduct well-designed trials in this field. There is a need for large randomized trials of high methodological rigour in order to define any benefit from the use of IS regarding mortality.
Ludwig and colleagues (2011) examined if atelectasis can be avoided and if post-operative lung function is improved following major lung resections with the use of IPPB. Prospective analysis was carried out in 135 patients operated on between 2007 and 2009; 55 received IPPB and 80 did not receive IPPB. Pre- and post-operative lung function tests were similar in both groups. Pulmonary complications were observed in 19 % of patients without IPPB and 27 % of those who received this treatment. The authors were unable to find evidence that additional improvement in post-operative pulmonary function is achieved when adding IPPB to the standard physical therapy.
Cattano et al (2010) examined if a systematic use of IS prior to surgery could help patients to preserve their respiratory function better in the post-operative period. A total of 41 morbidly obese (body mass index [BMI] greater than 40 kg/m²) candidates for laparoscopic bariatric surgery were consented in the study. All patients were taught how to use an incentive spirometer but then were randomized blindly into 2 groups. The control group was instructed to use the incentive spirometer for 3 breaths, once-daily. The treatment group was requested to use the incentive spirometer for 10 breaths, 5 times per day. Twenty experimental (mean BMI of 48.9 +/- 5.67 kg/m²) and 21 control patients (mean BMI of 48.3 +/- 6.96 kg/m²) were studied. The initial mean inspiratory capacity (IC) was 2,155 +/- 650.08 (SD) cc and 2,171 +/- 762.98 cc in the experimental and control groups, respectively. On the day of surgery, the mean IC was 2,275 +/- 777.56 cc versus 2,254.76 +/- 808.84 cc, respectively. On post-operative day 1, both groups experienced a significant drop of their IC, with volumes of 1,458 +/- 613.87 cc (t-test, p < 0.001) and 1,557.89 +/- 814.67 cc (t-test, p < 0.010), respectively. The authors concluded that these findings suggested that pre-operative use of the IS does not lead to significant improvements of inspiratory capacity and that it is a not a useful resource to prevent post-operative decrease in lung function.
Carvalho et al (2011) performed a systematic review to evaluate the evidence of the use of IS for the prevention of post-operative pulmonary complications and for the recovery of pulmonary function in patients undergoing abdominal, cardiac and thoracic surgeries. Searches were performed in the following databases: Medline, Embase, Web of Science, PEDro and Scopus to select randomized controlled trials in which IS was used in pre- and/or post-operative in order to prevent post-operative pulmonary complications and/or recover lung function after abdominal, cardiac and thoracic surgery. Two reviewers independently assessed all studies. In addition, the studies quality was assessed using the PEDro scale. A total of 30 studies were included (14 abdominal, 13 cardiac and 3 thoracic surgery; n = 3,370 patients). In the analysis of the methodological quality, studies achieved a PEDro average score of 5.6, 4.7 and 4.8 points in abdominal, cardiac and thoracic surgeries, respectively. Five studies (3 abdominal, 1 cardiac and 1 thoracic surgery) compared the effect of the IS with control group (no intervention) and no difference was detected in the evaluated outcomes. The authors concluded that there was no evidence to support the use of IS in the management of surgical patients.
The AARC's clinical practice guideline on "Incentive spirometry" (Restrepo et al, 2011) provided the following recommendations:
- IS alone is not recommended for routine use in the pre-operative and post-operative setting to prevent post-operative pulmonary complications.
- Routine use of IS to prevent atelectasis in patients after upper-abdominal surgery is not recommended.
- Routine use of IS to prevent atelectasis after coronary artery bypass graft surgery is not recommended.
Contraindications of IS include:
- Patients who can not be instructed or supervised to assure appropriate use of the device
- Patients in whom co-operation is absent or patients unable to understand or demonstrate proper use of the device
- Very young patients and others with developmental delays
- Patients who are confused or delirious
- Patients who are heavily sedated or comatose
- Patients unable to deep breathe effectively due to pain, diaphragmatic dysfunction, or opiate analgesia
- Patients unable to generate adequate inspiration with a vital capacity less than 10 ml/kg or an inspiratory capacity less than 33 % of predicted normal
In a Cochrane review, Freitas et al (2012) compared the effects of IS for preventing post-operative pulmonary complications in adults undergoing coronary artery bypass graft (CABG). These investigators searched CENTRAL and DARE on The Cochrane Library (Issue 2 of 4 2011), MEDLINE OVID (1948 to May 2011), EMBASE (1980 to Week 20 2011), LILACS (1982 to July 2011) , the Physiotherapy Evidence Database (PEDro) (1980 to July 2011), Allied & Complementary Medicine (AMED) (1985 to May 2011), CINAHL (1982 to May 2011). Randomized controlled trials comparing IS with any type of prophylactic physiotherapy for prevention of post-operative pulmonary complications in adults undergoing CABG were selected. Two reviewers independently evaluated trial quality using the guidelines of the Cochrane Handbook for Systematic Reviews and extracted data from included trials. For continuous outcomes, they used the generic inverse variance method for meta-analysis; and for dichotomous data they used the Peto Odds Ratio. This update of the 2007 review included 592 participants from 7 studies (2 new and 1 that had been excluded in the previous review in 2007. There was no evidence of a difference between groups in the incidence of any pulmonary complications and functional capacity between treatment with IS and treatment with physical therapy, positive pressure breathing techniques (including continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP) and IPPB, active cycle of breathing techniques (ACBT) or pre-operative patient education. Patients treated with IS had worse pulmonary function and arterial oxygenation compared with positive pressure breathing. Based on these studies there was no improvement in the muscle strength between groups who received IS demonstrated by maximal inspiratory pressure and maximal expiratory pressure. The authors concluded that this review suggested that there is no evidence of benefit from IS in reducing pulmonary complications and in decreasing the negative effects on pulmonary function in patients undergoing CABG. In view of the modest number of patients studied, methodological shortcomings and poor reporting of the included trials, these results should still be interpreted cautiously. An appropriately powered trial of high methodological rigor is needed to determine if there are patients who may derive benefit from IS following CABG.
In a Cochrane review, Bjornson et al (2013) evaluated the effectiveness (measured by croup scores, rate of intubation and health care utilization such as rate of hospitalization) and safety (frequency and severity of side effects) of nebulized epinephrine versus placebo in children with croup, evaluated in an emergency department (ED) or hospital setting. These investigators searched CENTRAL 2013, Issue 6, MEDLINE (1966 to Week 3 of June 2013), EMBASE (1980 to July 2013), Web of Science (1974 to July 2013), CINAHL (1982 to July 2013) and Scopus (1996 to July 2013). Randomized controlled trials (RCTs) or quasi-RCTs of children with croup evaluated in an ED or admitted to hospital were selected for analysis. Comparisons were: nebulized epinephrine versus placebo, racemic nebulized epinephrine versus L-epinephrine (an isomer) and nebulized epinephrine delivered by IPPB versus nebulized epinephrine without IPPB. Primary outcome was change in croup score post-treatment. Secondary outcomes were rate and duration of intubation and hospitalization, croup return visit, parental anxiety and side effects. Two authors independently identified potentially relevant studies by title and abstract (when available) and examined relevant studies using a priori inclusion criteria, followed by methodological quality assessment. One author extracted data while the second checked accuracy. These researchers used the standard methodological procedures expected by the Cochrane Collaboration. A total of 8 studies (225 participants) were included. In general, children included in the studies were young (average age of less than 2 years in the majority of included studies). Severity of croup was described as moderate-to-severe in all included studies. Six studies took place in the inpatient setting, 1 in the ED and 1 setting was not specified. Six of the 8 studies were deemed to have a low-risk of bias and the risk of bias was unclear in the remaining 2 studies. Nebulized epinephrine was associated with croup score improvement 30 minutes post-treatment (3 RCTs, standardized mean difference (SMD) -0.94; 95 % CI: -1.37 to -0.51; I(2) statistic = 0 %). This effect was not significant 2 and 6hours post-treatment. Nebulized epinephrine was associated with significantly shorter hospital stay than placebo (1 RCT, MD -32.0 hours; 95 % CI: -59.1 to -4.9). Comparing racemic and L-epinephrine, no difference in croup score was found after 30 minutes (SMD 0.33; 95 % CI: -0.42 to 1.08). After 2 hours, L-epinephrine showed significant reduction compared with racemic epinephrine (1 RCT, SMD 0.87; 95 % CI: 0.09 to 1.65). There was no significant difference in croup score between administration of nebulized epinephrine via IPPB versus nebulization alone at 30 minutes (1 RCT, SMD -0.14; 95 % CI: -1.24 to 0.95) or 2 hours (SMD -0.72; 95 % CI: -1.86 to 0.42). None of the studies sought or reported data on adverse effects. The authors concluded that nebulized epinephrine is associated with clinically and statistically significant transient reduction of symptoms of croup 30 minutes post-treatment. Evidence does not favor racemic epinephrine or L-epinephrine, or IPPB over simple nebulization. Moreover, they noted that data and analyses were limited by the small number of relevant studies and total number of participants and thus most outcomes contained data from very few or even single studies.
An UpToDate review on “Croup: Pharmacologic and supportive interventions” (Woods, 2014a) stated that “Administration of epinephrine does not alter the natural history of croup in the short (>2 hours) or longer term (24 to 36 hours). In the studies described above, racemic epinephrine was administered either by nebulization alone or by nebulization combined with intermittent positive pressure breaths. Another study compared these two methods [nebulization alone or by nebulization combined with IPPB] of administration and found them to be similarly effective”. Furthermore, an UpToDate review on “Croup: Approach to management” (Woods, 2014b) does not mention IPPB as a therapeutic option.