Pursed Lip Breathing: Abstracts and References

- Updated on August 3, 2021

This web page provides mainly abstract of medical research studies devoted to analysis of effects of pursed lip breathing exercises, suggestions, hypothesis, and results of clinical trials.

For detailed analysis of the pursed lip breathing technique exercises, with health conditions addressed (including COPD, asthma, emphysema, cystic fibrosis, stroke, hypertension, and some others), effects, instructions, and analysis, visit Pursed Lip Breathing.


Zhongguo Wei Zhong Bing Ji Jiu Yi Xue. 2008 Oct;20(10):607-10.
[A randomized controlled trial study of pulmonary rehabilitation with respiratory physiology as the guide on prognosis in patients with chronic obstructive pulmonary disease].
[Article in Chinese]
Zhang ZQ, Chen RC, Yang QK, Li P, Wang CZ, Zhang ZH.
Guangzhou Institute of Respiratory Diseases, First Affiliated Hospital, Guangzhou Medical College, Guangzhou 510120, Guangdong, China.
OBJECTIVE: To observe the effect of pulmonary rehabilitation with respiratory physiology as guide in patients with chronic obstructive pulmonary disease (COPD).
METHODS: Sixty patients of severe and very severe COPD as categorized by global proposed diagnostic criteria for COPD (GOLD, 2006) were enrolled for study. They were randomly divided into three groups, and with 20 patients in each group. The patients in group A were given pulmonary rehabilitation guided by respiratory physiology thrice a day, 15 minutes each time for 8 weeks. The patients in group B were given pulmonary rehabilitation with pursed lip respiration thrice a day, 15 minutes per time for 8 weeks. The patients in group C were given no pulmonary rehabilitation. Six minute-walk-distance (6MWD), medical research council (MRC) dyspnea scale, activities of daily living (ADL), maximal expiratory pressure (MEP), maximal inspiratory pressure (MIP), and quality of life (QOL) were determined before and after respective pulmonary rehabilitation course.
RESULTS: (1) There were 3, 5, 5 patients in group A, group B, group C dropped off in the course of rehabilitation respectively. (2) The patients’ MRC grade after pulmonary rehabilitation in group A and group B decreased compared with that before pulmonary rehabilitation (both P<0.01), but the difference was not significant between two groups (P>0.05). (3) 6MWD, ADL, MEP, MIP of patients in group A and group B increased after pulmonary rehabilitation compared with that before pulmonary rehabilitation, and 6MWD, ADL, MEP, MIP of patients in group A were increased after pulmonary rehabilitation more than those in group B (P<0.05 or P<0.01). (4)The patients’ body status, shortness of breath, social activity, home chores in group A and group B, and uneasiness in group A after pulmonary rehabilitation were improved more than those before pulmonary rehabilitation (P<0.05 or P<0.01), but the difference in state of mind, headache, appetite was not markedly different before and after pulmonary rehabilitation in two groups (all P>0.05). The difference in QOL was not marked between group A and group B after pulmonary rehabilitation (all P>0.05).
CONCLUSION: (1) The pulmonary rehabilitation with pursed lip respiration and the pulmonary rehabilitation with the guide of respiratory physiology ameliorates dyspnea, improves ADL, QOL, exercise tolerance, function of respiratory muscle in the severe and very severe COPD patients remarkably. (2) The effect of the pulmonary rehabilitation with the guide of respiratory physiology is better than that of the pulmonary rehabilitation with pursed lip respiration, and it can be considered as a more effective pulmonary rehabilitation method for the patients with severe and very severe COPD.

Int J Chron Obstruct Pulmon Dis. 2006;1(4):381-400.
Hyperinflation and its management in COPD.
Puente-Maestu L, Stringer WW.
Hospital General Universitario Gregorio Mara��n, Servicio de Neumologia, Madrid, Spain. lpuente.hgugm@madrid.salud.org
Chronic obstructive pulmonary disease (COPD) is characterized by poorly reversible airflow limitation. The pathological hallmarks of COPD are inflammation of the peripheral airways and destruction of lung parenchyma or emphysema. The functional consequences of these abnormalities are expiratory airflow limitation and dynamic hyperinflation, which then increase the elastic load of the respiratory system and decrease the performance of the respiratory muscles. These pathophysiologic features contribute significantly to the development of dyspnea, exercise intolerance and ventilatory failure. Several treatments may palliate flow limitation, including interventions that modify the respiratory pattern (deeper, slower) such as pursed lip breathing, exercise training, oxygen, and some drugs. Other therapies are aimed at its amelioration, such as bronchodilators, lung volume reduction surgery or breathing mixtures of helium and oxygen. Finally some interventions, such as inspiratory pressure support, alleviate the threshold load associated to flow limitation. The degree of flow limitation can be assessed by certain spirometry indexes, such as vital capacity and inspiratory capacity, or by other more complexes indexes such as residual volume/total lung capacity or functional residual capacity/total lung capacity. Two of the best methods to measure flow limitation are to superimpose a flow-volume loop of a tidal breath within a maximum flow-volume curve, or to use negative expiratory pressure technique. Likely this method is more accurate and can be used during spontaneous breathing. A definitive definition of dynamic hyperinflation is lacking in the literature, but serial measurements of inspiratory capacity during exercise will document the trend of end-expiratory lung volume and allow establishing relationships with other measurements such as dyspnea, respiratory pattern, exercise tolerance, and gas exchange.

Behav Modif. 2003 Oct;27(5):710-30.
Behavioral interventions in asthma. Breathing training.
Ritz T, Roth WT.
Psychological Institute III, University of Hamburg, Germany. Thomas.ritz@uni-hamburg.de
Breathing exercises are frequently recommended as an adjunctive treatment for asthma. A review of the current literature found little that is systematic documenting the benefits of these techniques in asthma patients. The physiological rationale of abdominal breathing in asthma is not clear, and adverse effects have been reported in chronic obstructive states. Theoretical analysis and empirical observations suggest positive effects of pursed-lip breathing and nasal breathing but clinical evidence is lacking. Modification of breathing patterns alone does not yield any significant benefit. There is limited evidence that inspiratory muscle training and hypoventilation training can help reduce medication consumption, in particular beta-adrenergic inhaler use. Breathing exercises do not seem to have any substantial effect on parameters of basal lung function. Additional research is needed on the psychological and physiological mechanisms of individual breathing techniques in asthma, differential effects in subgroups of asthma patients, and the generalization of training effects on daily life.

Medsurg Nurs. 2000 Aug;9(4):178-82.
Helping patients with COPD manage episodes of acute shortness of breath.
Truesdell S.
Division of Pulmonary and Critical Care Medicine, Henry Ford Hospital, Detroit, MI, USA.
The most disabling and frightening symptom experienced by patients with COPD is dyspnea. Even with the use of bronchodilators, the symptom may not be completely relieved. Patients often develop their own strategies for managing shortness of breath, including the use of a breathing technique called pursed-lip breathing. Although most nurses are familiar with this breathing technique, they often have difficulty assisting patients to use it during acute episodes of shortness of breath. A strategy is described which nurses can use to assist patients in implementing pursed-lip breathing effectively during episodes of acute dyspnea.

Nihon Kokyuki Gakkai Zasshi. 1998 Aug;36(8):679-83.
[Effects of a short-term pulmonary rehabilitation program on patients with chronic respiratory failure due to pulmonary emphysema].
[Article in Japanese]
Onodera A, Yazaki K.
Division of Respiratory Medicine, Yuri Kumiai General Hospital, Akita, Japan.
To evaluate the effects of a short-term pulmonary rehabilitation program on dyspnea, exercise capacity, and lung function, 15 patients with chronic respiratory failure due to pulmonary emphysema were enrolled in such a program for 3 weeks as inpatients. The program consisted of pursed lip breathing, diaphragmatic breathing, respiratory muscle stretch gymnastics, and walking with synchronized breathing. Dyspnea as measured with a visual analogue scale at the end of a 6-minute walk before and after the program (49.7 +/- 4.0% to 24.2 +/- 3.8%) decreased significantly (p < 0.01). As a measure of functional exercise capacity, the 6-minute walking distance (226.9 +/- 32.4 m to 292.1 +/- 35.8 m) increased significantly (p < 0.01). As an indicator of maximal exercise capacity, endurance time on an incremental treadmill test did not improve. Spirometric data did not change during the study. Total lung capacity (TLC) (8.44 +/- 0.70 L to 7.58 +/- 0.74 L) and residual volume (RV) (5.13 +/- 0.53 L to 4.28 +/- 0.59 L) decreased significantly (p < 0.01). The findings suggest that this program relieves dyspnea, increases functional exercise capacity, and decreases TLC and RV on patients with chronic respiratory failure due to pulmonary emphysema.

Chest. 1992 Jan;101(1):75-8.
The pattern of respiratory muscle recruitment during pursed-lip breathing.
Breslin EH.
Boston College.
Data from the present study indicate a change in the pattern of chest wall muscle recruitment and improved ventilation with pursed-lip breathing (PLB) in COPD. Pursed lip breathing led to increased rib cage and accessory muscle recruitment during inspiration and expiration, increased abdominal muscle recruitment during expiration, decreased duty cycle of the inspiratory muscles and respiratory rate, and improved SaO2. In addition, PLB resulted in no change in pressure across the diaphragm and a less fatiguing breathing pattern of the diaphragm. Changes in chest wall muscle recruitment and respiratory temporal parameters concomitant with the increased SaO2 indicate a mechanism of improving ventilation with PLB while protecting the diaphragm from fatigue in COPD. Alterations in the pattern of respiratory muscle recruitment with PLB may be associated also with the amelioration of dyspnea. Further investigation is necessary to explore the relationship between the pattern of respiratory muscle recruitment during PLB and dyspnea.

Clin Rehabil. 2010 Mar;24(3):240-50. Epub 2010 Feb 15.
Respiratory muscle training improves cardiopulmonary function and exercise tolerance in subjects with subacute stroke: a randomized controlled trial.
Sutbeyaz ST, Koseoglu F, Inan L, Coskun O.
OBJECTIVE: To determine whether two types of exercise–breathing retraining (BRT) and inspiratory muscle training (IMT)–improve on cardiopulmonary functions and exercise tolerance in patients with stroke.
DESIGN: A randomized controlled trial.
SETTING: Education and research hospital.
SUBJECTS: Forty-five inpatients with stroke (24 men, 21 women) were recruited for the study. The subjects were randomized into three groups: 15 assigned to receive inspiratory muscle training (IMT); 15 assigned to received breathing retraining, diaphragmatic breathing and pursed-lips breathing (BRT); 15 assigned to a control group.
INTERVENTIONS: All study groups participated in a conventional stroke rehabilitation programme. For the same period, the IMT and BRT groups trained daily, six times a week, with each session consisting of one half-hour of training for six weeks.
MAIN MEASURES: Each subject underwent pulmonary function and cardiopulmonary exercise tests. Subjects were also assessed for exertional dyspnoea, stages of motor recovery, ambulation status, activity of daily living and quality of life.
RESULTS: After the training programme, the IMT group had significantly improved forced expiratory volume at 1 second (FEV(1)), forced vital capacity (FVC), vital capacity (VC), forced expiratory flow rate 25-75% (FEF 25-75%) and maximum voluntary ventilation (MVV) values compared with the BRT and control groups, although there were no significant differences between the BRT and control groups (P<0.01). Peak expiratory flow rate (PEF) value was increased significantly in the BTR group compared with the IMT and control groups. The IMT group also had significantly higher peak oxygen consumption (Vo(2peak)) than the BRT and control groups, although there were no significant differences between the BRT and control groups (P<0.001). There was a statistically significant increase in maximum inspiratory pressure (PI(max)) and maximum inspiratory and expiratory pressure (PE(max)) in the BRT group and, PI(max) in the IMT group compared with baseline and the control group. In the IMT group, this was associated with improvements in exercise capacity, sensation of dyspnoea and quality of life.
CONCLUSIONS: Significant short-term effects of the respiratory muscle training programme on respiratory muscle function, exercise capacity and quality of life were recorded in this study.

Neurology. 2007 Aug 7;69(6):582-5.
Respiratory countermaneuvers in autonomic failure.
Thijs RD, Wieling W, van den Aardweg JG, van Dijk JG.
Department of Neurology and Clinical Neurophysiology, Leiden University Medical Centre, Leiden, the Netherlands. r.d.thijs@lumc.nl
BACKGROUND: Selective increase of inspiratory impedance augments blood pressure in healthy subjects through activation of the respiratory pump. We studied the efficacy of respiratory maneuvers to reduce orthostatic hypotension in autonomic failure.
METHODS: Mean arterial pressure (MAP) after standing up was recorded in 10 patients in five conditions: normal standing, leg muscle tensing, inspiratory pursed lips breathing, inspiratory sniffing, and a device causing inspiratory obstruction.
RESULTS: The maneuvers caused significant differences in standing MAP. Inspiratory obstruction and leg muscle tensing increased MAP to a comparable degree. The effect of inspiratory pursed lips breathing and inspiratory sniffing depended on concomitant hyperventilation.
CONCLUSION: Respiratory maneuvers reduce orthostatic hypotension in autonomic failure through activation of the respiratory pump, provided hyperventilation is avoided.

Appl Psychophysiol Biofeedback. 2006 Mar;31(1):37-49.
Short-term effects of a brief respiratory training on baroreceptor cardiac reflex function in normotensive and mild hypertensive subjects.
Reyes del Paso GA, Cea JI, Gonz�lez-Pinto A, Cabo OM, Caso R, Brazal J, Mart�nez B, Hern�ndez JA, Gonz�lez MI.
Departamento de Psicolog�a, Facultad de Humanidades y CC.EE, Universidad de Ja�n, 23071, Ja�n, Spain. greyes@ujaen.es
Baroreceptor cardiac reflex sensitivity is reduced in hypertension and is considered a powerful prognostic factor in cardiovascular health. This study analyzes the acute effects of a brief respiratory training on baroreceptor sensitivity and on two new proposed baroreflex parameters: baroreceptor power (i.e., the percentage of cardiac beats regulated by the baroreflex) and effectiveness (i.e., the frequency in which the baroreflex responds to transient alterations in blood pressure). Twenty-two participants, 10 primary mild hypertensives and 12 normotensives, learned and practiced a respiratory pattern characterized by breathing at 6 bpm, with time of expiration being twice time of inspiration, predominantly abdominal, and with pursed lips. Baroreceptor parameters are differentiated in terms of increases (“up” sequences) or decreases (“down” sequences) in blood pressure. Irrespective of the groups, the breathing manipulation increased baroreceptor sensitivity (only in the “up” sequences), power, and effectiveness (only in the “down” sequences). These results suggest that this type of respiratory training could be used as a promising intervention to increase baroreceptor cardiac function in primary hypertension.

Chest. 2006 Feb;129(2):278-84.
Heart rate variability biofeedback: effects of age on heart rate variability, baroreflex gain, and asthma.
Lehrer P, Vaschillo E, Lu SE, Eckberg D, Vaschillo B, Scardella A, Habib R.
Department of Psychiatry, UMDNJ-Robert Wood Johnson Medical School, 671 Hoes Lane, Piscataway, NJ 08854, USA. lehrer@umdnj.edu
OBJECTIVES: To present additional analysis of data from a previously published study showing that biofeedback training to increase heart rate variability (HRV) can be an effective component in asthma treatment. HRV and intervention-related changes in HRV are negatively correlated with age. Here we assess the effects of age on biofeedback effects for asthma.
DESIGN: Ten sessions of HRV biofeedback were administered to 45 adults with asthma. Medication was prescribed by blinded physicians according to National Heart, Lung, and Blood Institute criteria. Medication needs were reassessed biweekly.
RESULTS: Decreases in need for controller medication were independent of age. There were larger acute decreases in forced oscillation frequency dependence in the older group but larger increases in HRV variables in the younger group. Differences between age groups were smaller among subjects trained in pursed-lips abdominal breathing as well as biofeedback, than among those receiving only biofeedback.
CONCLUSIONS: Age-related attenuation of biofeedback effects on cardiovascular variability does not diminish the usefulness of the method for treating asthma among older patients. Additional training in pursed-lips abdominal breathing obliterates the effects of age on HRV changes during biofeedback.

Chest. 2005 Sep;128(3):1524-30.
Effects of 8-week, interval-based inspiratory muscle training and breathing retraining in patients with generalized myasthenia gravis.
Fregonezi GA, Resqueti VR, G�ell R, Pradas J, Casan P.
Departament de Pneumology, Area de Rehabilitaci�n Respiratoria, Hospital de la Santa Creu i de Sant Pau Av, Sant Antoni Maria Claret, 167 08025, Barcelona, Spain. gfreitas@hsp.santpau.es
STUDY OBJECTIVE: To assess the effect of interval-based inspiratory muscle training (IMT) combined with breathing retraining (BR) in patients with generalized myasthenia gravis (MG) in a partial home program.
DESIGN: A randomized controlled trial with blinding of outcome assessment.
SETTING: A secondary-care respiratory clinic.
PATIENTS: Twenty-seven patients with generalized MG were randomized to a control group or a training group.
INTERVENTIONS: The training group underwent interval-based IMT associated with BR (diaphragmatic breathing [DB] and pursed-lips breathing [PLB]) three times a week for 8 weeks. The sessions included 10 min each of DB, interval-based IMT, and PLB. Interval-based IMT consisted of training series interspersed with recovery time. The threshold load was increased from 20 to 60% of maximal inspiratory pressure (P(Imax)) over the 8 weeks.
MEASUREMENTS AND RESULTS: Lung function, respiratory pattern, respiratory muscle strength, respiratory endurance, and thoracic mobility were measured before and after the 8 weeks. The training group improved significantly compared to control group in P(Imax) (p = 0.001), maximal expiratory pressure (P(Emax)) [p = 0.01], respiratory rate (RR)/tidal volume (V(T)) ratio (p = 0.05), and upper chest wall expansion (p = 0.02) and reduction (p = 0.04). Significant differences were seen in the training group compared to baseline P(Imax) (p = 0.001), P(Emax) (p = 0.01), maximal voluntary ventilation (p = 0.02), RR/V(T) ratio (p = 0.003), Vt (p = 0.02), RR (p = 0.01), total time of RR (p = 0.01), and upper chest wall expansion (p = 0.005) and reduction (p = 0.005). No significant improvement was seen in lower chest wall or lung function.
CONCLUSIONS: The partial home program of interval-based IMT associated with BR is feasible and effective in patients with generalized MG. Improvements in respiratory muscle strength, chest wall mobility, respiratory pattern, and respiratory endurance were observed.

Chest. 2004 Aug;126(2):352-61.
Biofeedback treatment for asthma.
Lehrer PM, Vaschillo E, Vaschillo B, Lu SE, Scardella A, Siddique M, Habib RH.
Department of Psychiatry, Robert Wood Johnson Medical School, The University of Medicine and Dentistry of New Jersey, Piscataway, NJ 08854, USA. lehrer@umdnj.edu
STUDY OBJECTIVES: We evaluated the effectiveness of heart rate variability (HRV) biofeedback as a complementary treatment for asthma.
PATIENTS: Ninety-four adult outpatient paid volunteers with asthma.
SETTING: The psychophysiology laboratory at The University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, and the private outpatient offices of participating asthma physicians.
INTERVENTIONS: The interventions were as follows: (1) a full protocol (ie, HRV biofeedback and abdominal breathing through pursed lips and prolonged exhalation); (2) HRV biofeedback alone; (3) placebo EEG biofeedback; and (4) a waiting list control.
DESIGN: Subjects were first prestabilized using controller medication and then were randomly assigned to experimental groups. Medication was titrated biweekly by blinded asthma specialists according to a protocol based on National Heart, Lung, and Blood Institute guidelines, according to symptoms, spirometry, and home peak flows.
MEASUREMENTS: Subjects recorded daily asthma symptoms and twice-daily peak expiratory flows. Spirometry was performed before and after each weekly treatment session under the HRV and placebo biofeedback conditions, and at triweekly assessment sessions under the waiting list condition. Oscillation resistance was measured approximately triweekly.
RESULTS: Compared with the two control groups, subjects in both of the two HRV biofeedback groups were prescribed less medication, with minimal differences between the two active treatments. Improvements averaged one full level of asthma severity. Measures from forced oscillation pneumography similarly showed improvement in pulmonary function. A placebo effect influenced an improvement in asthma symptoms, but not in pulmonary function. Groups did not differ in the occurrence of severe asthma flares.
CONCLUSIONS: The results suggest that HRV biofeedback may prove to be a useful adjunct to asthma treatment and may help to reduce dependence on steroid medications. Further evaluation of this method is warranted.

Appl Psychophysiol Biofeedback. 2000 Sep;25(3):193-200.
Respiratory sinus arrhythmia biofeedback therapy for asthma: a report of 20 unmedicated pediatric cases using the Smetankin method.
Lehrer P, Smetankin A, Potapova T.
Department of Psychiatry, Robert W. Johnson Medical School, Piscataway, NJ 08854, USA.
This multiple case study describes pulmonary function changes in 20 asthmatic children from 30 consecutive cases undergoing biofeedback training for increasing the amplitude of respiratory sinus arrhythmia (RSA). The Smetankin protocol was used, which, in addition to RSA biofeedback, includes instructions in relaxed abdominal pursed-lips breathing. Ten individuals were excluded, including 6 who had been taking asthma medication, 2 who developed viral infections during the treatment period, and 2 who dropped out prior to completing treatment. Patients each received 13 to 15 sessions of training. Asthma tended to be mild, with mean spirometric values close to normal levels. Nevertheless, significant improvements were noted in 2 spirometry measures taken during forced expiratory maneuvers from maximum vital capacity: FEV1 and FEF50. These preliminary uncontrolled data suggest that the Smetankin protocol warrants further evaluation as a nonpharmacological psychophysiological treatment for this condition, although these data could not definitively prove that the method is effective.

Arch Phys Med Rehabil. 2000 Apr;81(4):472-8.
Pursed lips breathing improves ventilation in myotonic muscular dystrophy.
Ugalde V, Breslin EH, Walsh SA, Bonekat HW, Abresch RT, Carter GT.
Department of Physical Medicine and Rehabilitation, School of Medicine, University of California, Davis, USA.
OBJECTIVE: To determine the effects of pursed lips breathing on ventilation, chest wall mechanics, and abdominal muscle recruitment in myotonic muscular dystrophy (MMD).
DESIGN: Before-after trial.
SETTING: University hospital pulmonary function laboratory.
PARTICIPANTS: Eleven subjects with MMD and 13 normal controls.
INTERVENTION: Pursed lips breathing.
OUTCOME MEASURES: Electromyographic (EMG) activity of the transversus abdominis, external oblique, internal oblique, and rectus abdominis was recorded with simultaneous measures of gastric pressure, abdominal plethysmography, and oxygen saturation. Self-reported sensations of dyspnea, respiratory effort, and fatigue were recorded at the end of each trial.
RESULTS: Pursed lips breathing and deep breathing led to increased tidal volume, increased minute ventilation, increased oxygen saturation, reduced respiratory rate, and reduced endexpiratory lung volume. Dyspnea, respiratory effort, and fatigue increased slightly with pursed lips breathing. EMG activity of the transversus abdominis and internal oblique muscles increased in MMD only and was associated with an increase in gastric pressure.
CONCLUSIONS: Pursed lips breathing and deep breathing are effective and easily employed strategies that significantly improve tidal volume and oxygen saturation in subjects with MMD. Abdominal muscle recruitment does not explain the ventilatory improvements, but reduced end-expiratory lung volume may increase the elastic recoil of the chest wall. Further clinical studies are needed to ascertain if the ventilatory improvements with pursed lips breathing and deep breathing improve pulmonary outcomes in MMD.

Br J Surg. 1997 Nov;84(11):1535-8.
Randomized controlled trial of prophylactic chest physiotherapy in major abdominal surgery.
Fagevik Ols�n M, Hahn I, Nordgren S, L�nroth H, Lundholm K.
Department of Physiotherapy, University of G�teborg, Sweden.
INTRODUCTION: This randomized controlled study evaluated the clinical benefit and physiological effects of prophylactic chest physiotherapy in open major abdominal surgery.
METHODS: A group of 174 patients received chest physiotherapy including breathing with pursed lips, huffing and coughing, and information about the importance of early mobilization. In addition high-risk patients were given resistance training on inspiration and expiration with a mask. The resistance used during inspiration was -5 cmH2O and that during expiration +10 cmH2O. The control group (194 patients) received no information or treatment unless a pulmonary complication occurred.
RESULTS: Oxygen saturation on postoperative days 1-3 was significantly greater in the treatment group. Treated patients were mobilized significantly earlier. No difference was noted in peak expiratory flow rate or forced vital capacity. Postoperative pulmonary complications occurred in 6 per cent of patients in the treatment group and in 27 per cent of controls (P < 0.001). In high-risk patients the numbers with pulmonary complications were six of 40 and 20 of 39 respectively. Pulmonary complications were particularly common in patients with morbid obesity.
CONCLUSION: Preoperative chest physiotherapy reduced the incidence of postoperative pulmonary complications and improved mobilization and oxygen saturation after major abdominal surgery.

Physiother Res Int. 1997;2(3):167-77.
Respiratory muscle activity and pulmonary function during acutely induced airways obstruction.
van der Schans CP, de Jong W, de Vries G, Postma DS, Ko�ter GH, van der Mark TW.
Department of Rehabilitation, University Hospital, Groningen, The Netherlands.
BACKGROUND: Patients with airway obstruction may spontaneously breathe with a positive expiratory pressure by pursing their lips during expiration, especially in case of dyspnea. Dyspnea seems to be related to increased activity of the respiratory muscles. A potential explanation for the use of pursed lips breathing (PLB) is that this type of breathing leads to a reduction of respiratory muscle activity. The purpose of this study was to assess the effect of breathing with a positive expiratory pressure of 5 cm H2O, simulating pursed lips breathing (SPLB), on respiratory muscle activity and pulmonary function during induced airway obstruction.
METHODS: In twelve asthmatic patients, tonic and phasic electromyographic (EMG) activity of the following muscles was obtained: scalene muscle, parasternal muscle, and abdominal muscles. Pulmonary function and EMG measurements were performed before and after propranolol induced airway obstruction.
RESULTS: Simulated pursed lips breathing resulted in a significant increase of functional residual capacity and tidal volume both at baseline and during airway obstruction. Phasic respiratory muscle activity during PEP breathing increased especially at baseline. We conclude that beneficial effects of breathing with a positive expiratory pressure of 5 cm H2O, which is similar to pursed lips breathing, cannot be explained by changes in respiratory muscle activity or pulmonary function.

Zhonghua Jie He He Hu Xi Za Zhi. 1991 Oct;14(5):283-4, 319.
[Application of pursed lips breathing to chronic obstructive pulmonary disease patients with respiratory insufficiency].
[Article in Chinese]
Bai CX.
Zhongshan Hospital, Shanghai Medical University.
Eighteen COPD patients with respiratory insufficiency received the treatment of pursed lips breathing. The results showed that respiratory rate reduced (from 21.4 +/- 12.6 to 14.8 +/- 4.1 breath/min) and tidal volume increased (from 356.9 +/- 96.7 to 462.0 +/- 147.1 ml) significantly. In the meantime, arterial partial pressure of carbon dioxide decreased and arterial partial pressure of oxygen increased significantly (all p values less than 0.01).

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