Prevention Of Atelectasis Research Articles

The Effect of Recruitment Maneuver on Static Lung Compliance in Patients Undergoing General Anesthesia for Laparoscopic Cholecystectomy: A Single-Centre Prospective Clinical Intervention Study.

Background and Objectives: The aim of this study was to examine whether the use of an alveolar recruitment maneuver (RM) leads to a significant increase in static lung compliance (Cstat) and an improvement in gas exchange in patients undergoing laparoscopic cholecystectomy. Material and Methods: A clinical prospective intervention study was conducted. Patients were divided into two groups according to their body mass index (BMI): normal-weight (group I) and pre-obese and obese grade I (group II). Lung mechanics were monitored (Cstat, dynamic compliance-Cdin, peak pressure-Ppeak, plateau pressure-Pplat, driving pressure-DP) alongside gas exchange, and hemodynamic changes (heart rate-HR, mean arterial pressure-MAP) at six time points: T1 (induction of anesthesia), T2 (formation of pneumoperitoneum), T3 (RM with a PEEP of 5 cm H2O), T4 (RM with a PEEP of 7 cm H2O), T5 (desufflation), and T6 (RM at the end). The RM was performed by increasing the peak pressure by +5 cm of H2O at an equal inspiration-to-expiration ratio (I/E = 1:1) and applying a PEEP of 5 and 7 cm of H2O. Results: Out of 96 patients, 33 belonged to group I and 63 to group II. An increase in Cstat values occurred after all three RMs. At each time point, the Cstat value was measured higher in group I than in group II. A higher increase in Cstat was observed in group II after the second and third RM. Cstat values were higher at the end of the surgical procedure compared to values after the induction of anesthesia. The RM led to a significant increase in PaO2 in both groups without changes in HR or MAP. Conclusions: During laparoscopic cholecystectomy, the application of RM leads to a significant increase in Cstat and an improvement in gas exchange. The prevention of atelectasis during anesthesia should be initiated immediately after the induction of anesthesia, using protective mechanical ventilation and RM.

Efficacy of Incentive Spirometry in Expiratory Muscle Training Following Abdominal Surgery

BACKGROUND: Incentive spirometry is a device which helps in the improvement of lung function after abdominal surgery. It motivates the patients by giving visual feedback about their lung volumes. It is one of the less expensive and user-friendlydevices. Incentive spirometry facilitates the patients to take slow deep breath and there by producing a sustained maximal inspiration (SMI) that mainly helps in the prevention of atelectasis. But it is a common practice for physiotherapists to teach the patients to do expiratory exercise by reversing the incentive spirometer. The simplest way to measure the maximal inspiratory and expiratory pressures is by respiratory pressure meter in cmH2o. OBJECTIVE: To find out the efficacy of incentive spirometer in improving the expiratory muscle strength following abdominal surgery. METHODOLOGY: Quasi-Experimental study. PROCEDURE: 30 subjects were conveniently selected based on inclusion and exclusion criteria and allotted to group A (n=15) and group B (n= 15). Both groups were trained for inspiratory muscle and group A was also trained for expiratory muscle using incentive spirometry. OUTCOME MEASURES: Maximal inspiratory pressure (MIP), Maximal expiratory pressure (MEP). RESULT: This study shows that the mean MIP value have improved from 2nd to 7th postoperative day, but it is not statistically significant (P>0.05). The mean MEP values shows statistically significant (P<0.05) improvement from second to 7th postoperative day in group A when compared to group B. CONCLUSION:This study concludes that there is significant improvement in the expiratory muscle strength along with inspiratory muscle strength by training with the Incentive spirometry in the upside down and upright positions respectively.

Prevention of atelectasis by continuous positive airway pressure in anaesthetised children: A randomised controlled study.

Continuous positive airway pressure (CPAP) prevents peri-operative atelectasis in adults, but its effect in children has not been quantified. The aim of this study was to evaluate the role of CPAP in preventing postinduction and postoperative atelectasis in children under general anaesthesia. A randomised controlled study. Single-institution study, community hospital, Mar del Plata. Argentina. We studied 42 children, aged 6 months to 7 years, American Society of Anesthesiologists physical status class I, under standardised general anaesthesia. Patients were randomised into two groups: Control group (n = 21): induction and emergence of anaesthesia without CPAP; and CPAP group (n = 21): 5 cmH2O of CPAP during induction and emergence of anaesthesia. Lung ultrasound (LUS) imaging was performed before and 5 min after anaesthesia induction. Children without atelectasis were ventilated in the same manner as the Control group with standard ventilatory settings including 5 cmH2O of PEEP. Children with atelectasis received a recruitment manoeuvre followed by standard ventilation with 8 cmH2O of PEEP. Then, at the end of surgery, LUS images were repeated before tracheal extubation and 60 min after awakening. Lung aeration score and atelectasis assessed by LUS. Before anaesthesia, all children were free of atelectasis. After induction, 95% in the Control group developed atelectasis compared with 52% of patients in the CPAP group (P < 0.0001). LUS aeration scores were higher (impaired aeration) in the Control group than the CPAP group (8.8 ± 3.8 vs. 3.5 ± 3.3 points; P < 0.0001). At the end of surgery, before tracheal extubation, atelectasis was observed in 100% of children in the Control and 29% of the CPAP group (P < 0.0001) with a corresponding aeration score of 9.6 ± 3.2 and 1.8 ± 2.3, respectively (P < 0.0001). After surgery, 30% of children in the Control group and 10% in the CPAP group presented with residual atelectasis (P < 0.0001) also corresponding to a higher aeration score in the Control group (2.5 ± 3.1) when compared with the CPAP group (0.5 ± 1.5; P < 0.01). The use of 5 cmH2O of CPAP in healthy children of the studied age span during induction and emergence of anaesthesia effectively prevents atelectasis, with benefits maintained during the first postoperative hour. Clinicaltrials.gov NCT03461770.

Determination of Best PEEP (Positive End-expiratory Pressure) in Anesthetized Infants in Terms of Prevention of Atelectasis

Determination of Best PEEP (Positive End-expiratory Pressure) in Anesthetized Infants in Terms of Prevention of Atelectasis

Analysis of different levels of positive end-expiratory pressure during lung retrieval for transplantation: an experimental study.

Atelectasis and inadequate oxygenation in lung donors is a common problem during the retrieval of these organs. Nevertheless, the use of high positive end-expiratory pressure (PEEP) is not habitual during procedures of lung retrieval. Twenty-one Sprague-Dawley male consanguineous rats were used in the study. The animals were divided into 3 groups according to the level of PEEP used: low (2 cmH2O), moderate (5 cmH2O), and high (10 cmH2O). Animals were ventilated with a tidal volume of 6 mL/kg. Before lung removal, the lungs were inspected for the presence of atelectasis. When atelectasis was detected, alveolar recruitment maneuvers were performed. Blood gasometric analysis was performed immediately. Finally, the lungs were retrieved, weighed, and submitted to histological analysis. The animals submitted to higher PEEP showed higher levels of oxygenation with the same tidal volumes PO2=262.14 (PEEP 2), 382.4 (PEEP 5), and 477.0 (PEEP 10). The occurrence of atelectasis was rare in animals with a PEEP of 10 cmH2O, which therefore required less frequent recruitment maneuvers (need for recruitment: PEEP 2=100%, PEEP 5 =100%, and PEEP 10=14.3%). There was no change in hemodynamic stability, occurrence of pulmonary edema, or other histological injuries with the use of high PEEP. The use of high PEEP (10 cmH2O) was feasible and probably a beneficial strategy for the prevention of atelectasis and the optimization of oxygenation during lung retrieval. Clinical studies should be performed to confirm this hypothesis.

The effect of intrapulmonary percussive ventilation in pediatric patients: A systematic review.

Intrapulmonary percussive ventilation (IPV) is frequently used in clinical practice to enhance sputum evacuation and lung recruitment. However, the evidence in different respiratory pathologies, especially in children, is still lacking. This systematic review aims to enlist the effectiveness of IPV as an airway clearance technique in pediatric patients. A systematic literature search was performed in PubMed, Web of Science, and the Cochrane Library databases. Studies were included if the subjects suffered from a respiratory disease requiring airway clearance and the mean age of the sample was <18 years. After screening, nine articles remained for further analysis. Three of the nine articles examined patients with cystic fibrosis (CF). No significant differences in lung function or expectorated mucus were found compared to conventional chest physiotherapy. On the other hand, significant beneficial results were found for the treatment or prevention of atelectasis in non-CF patients using IPV. Similar results were seen when comparing therapies for neuromuscular/neurological patients. One study found that IPV reduced hospital stay and improved the clinical status of children with acute bronchiolitis compared to no physiotherapy. Severe adverse events did not occur in the included studies. A limited number of studies investigated IPV in the pediatric population. Despite the heterogeneity across the studies and the small sample sizes, the results seem promising. IPV is suggested to be a safe and effective alternative for airway clearance. Future research is required to confirm these results and to further analyze the possible benefits in different respiratory pathologies.

A Comparative Study between Protective Lung Ventilation versus Conventional Ventilation in Obese Patients Undergoing Abdominal Laparoscopic Surgery

Background: Obesity is a serious problem worldwide. During general anesthesia and post-operative period, obese patients more likely to develop post-operative pulmonary complications as atelectasis and impaired pulmonary function compared to non-obese. Intraoperative protective ventilation consisting of low tidal volume, high PEEP and recruitment maneuvers resulted in alveolar recruitment and optimization of intraoperative respiratory mechanics. Objective: This study tested two strategies of mechanical ventilation in obese patients to find out which is best regarding gas exchange optimization, airway mechanics and atelectasis score. Methods: Study was a randomized prospective comparative control study was carried out on 50 obese patients with BMI 30-50 kg/m2. Patients were prepared for laparoscopic cholecystectomy. Patient’s selection according to attendees at time of operation as a single numbers were protective ventilation (group A) and a double numbers were conventional ventilation (group B). Results: Study showed significance between preoperative and postoperative pulmonary function tests and revealed better POST FVC in group A mean 86.04 (± 10.35) L, while in group B was 74.96 (± 14.73) L, p value (0.021). Better POST FEV1 in group A mean 73.56 (± 16.49) L, while in group B was 56.92 (± 8.340) L, p value (0.046). Better post-operative oxygenation in protective ventilation (group A). Mean Post P (A-a) O2 in group A was 27.93 (±7.76) mmHg, while in group B was 35.82 (±11.98) mmHg, p value (0.022). Study found peak and plateau airway pressures were higher in protective group with no change in airway resistance. Pulmonary compliance was improved but, in this study revealed more alterations of the hemodynamics in the patients who were subjected to protective ventilation despite adequate preoperative fluid preload. Hemodynamic instability observed in 24% in group A, but only occurred in 8% in group B. Study found that protective ventilation was superior to standard ventilation in prevention of atelectasis development 64%of the cases in group A revealed normal postoperative CT Chest and 36% showed lamellar atelectasis. In group B, 48% of the cases showed normal postoperative CT Chest, 40% revealed lamellar atelectasis and 12% showed plate atelectasis. Conclusions: Study found protective ventilation was superior to conventional ventilation in prevention of lung atelectasis and associated with better oxygenation and pulmonary function tests in the post-operative in obese laparoscopic cholecystectomy. In spite of it was very effective in optimizing gas exchange, but associated with more hemodynamic affection.

The dual mode of ventilation ′pressure-controlled ventilation-volume guaranteed′ does not provide anymore benefit in obese anesthetized patients

Background Ventilatory strategies aim at the prevention of atelectasis and the improvement of oxygenation, but yet none is optimal. On comparing pressure-controlled ventilation (PCV) with volume-controlled ventilation (VCV) with the same tidal volume and inspiratory time, PCV tends to produce higher mean airway pressures, and thereby improves oxygenation. However, volume-targeted ventilators (VTV) allow to set the tidal volume directly. In order to deliver that volume. We compared PCV and pressure-controlled ventilation volume guaranteed (PCV-VG) with regard to the airway pressures produced when aiming to achieve the same tidal volume. Patients and methods Thirty obese ASA I-III patients scheduled for abdominal surgery were ventilated with PCV for 45 min; then, the PCV-VG mode was applied to all patients with the same parameters, targeting the same tidal volume of conventional PCV during the first phase. The plateau pressure and the mean airway pressure were recorded and compared between both modes. Vital signs, EtCO 2 , SpO 2 , arterial blood gases, and the oxygenation index were compared. Results No difference was observed between both modes of ventilation in terms of the plateau airway pressure (34.2 ΁ 1.8 vs. 34.1 ΁ 2.9 cmH 2 O, P = 0.484) and the mean airway pressure (13.4 ΁ 1.6 vs. 13.2 ΁ 1.8 cmH 2 O, P = 0.326). No significant difference was observed between PCV and PCV-VG with regard to the hemodynamics, EtCO 2 , and SpO 2 . No significant change was observed in the arterial blood gas analysis including pH (7.39 ΁ 0.3 versus 7.4 ΁ 0.2 with P value 0.204), PaCO 2 (30.8e 0.204) change in 0.2 with P value 0.06), PaO 2 (155.8 0.06)) change in0.2 with blood P value 0.316) and oxygenation index (4.34 oxygenation index.2 with bP value 0.176). ConclusionNo significant difference was observed between both modes of ventilation (PCV vs. PCV-VG) in obese patients.

Initial ventilator settings for critically ill patients

The lung-protective mechanical ventilation strategy has been standard practice for management of acute respiratory distress syndrome (ARDS) for more than a decade. Observational data, small randomized studies and two recent systematic reviews suggest that lung protective ventilation is both safe and potentially beneficial in patients who do not have ARDS at the onset of mechanical ventilation. Principles of lung-protective ventilation include: a) prevention of volutrauma (tidal volume 4 to 8 ml/kg predicted body weight with plateau pressure <30 cmH2O); b) prevention of atelectasis (positive end-expiratory pressure ≥5 cmH2O, as needed recruitment maneuvers); c) adequate ventilation (respiratory rate 20 to 35 breaths per minute); and d) prevention of hyperoxia (titrate inspired oxygen concentration to peripheral oxygen saturation (SpO2) levels of 88 to 95%). Most patients tolerate lung protective mechanical ventilation well without the need for excessive sedation. Patients with a stiff chest wall may tolerate higher plateau pressure targets (approximately 35 cmH2O) while those with severe ARDS and ventilator asynchrony may require a short-term neuromuscular blockade. Given the difficulty in timely identification of patients with or at risk of ARDS and both the safety and potential benefit in patients without ARDS, lung-protective mechanical ventilation is recommended as an initial approach to mechanical ventilation in both perioperative and critical care settings.

The Use of Intraoperative Positive End Expiratory Pressure

General anesthesia is associated with impaired gas exchange mainly because of increased shunt due to atelectasis in the dependent regions of the lung. Postoperative atelectasis is associated with adverse clinical outcomes in terms of hypoxic respiratory failure requiring endotracheal intubation and pneumonia secondary to impairment of ciliary and lymphatic functions. Prevention of atelectasis and/or airway closure could be a mechanism by which positive end expiratory pressure (PEEP) improves oxygenation. Positive end expiratory pressure has been used intraoperatively as a part of open lung and protective lung ventilation strategies. However, it is unclear at the present time whether the intraoperative use of PEEP is associated with a decrease in mortality or in the incidence of other important clinical surrogates of outcome such as postoperative respiratory failure. The aim of this review is to review the physiologic effects and history of PEEP, to present some of the current uses in specific surgical populations and comment on potential benefits on postoperative mortality and pulmonary complications that may be ascribed to intraoperative PEEP use.

Prevention of Atelectasis in Morbidly Obese Patients During General Anesthesia and Paralysis

Survey of Anesthesiology: October 2010 - Volume 54 - Issue 5 - p 224-225 doi: 10.1097/01.SA.0000387955.46927.ca

Observation on efficacy of compositive chest physiotherapy for the prevention of atelectasis after thoracotomy in the elderly patients

Objective To investigate the clinical effect of compositive chest physiotherapy for the prevention of atelectasis after thoracotomy in the elderly patients.Methods Sixty-eight elderly patients after thoracotomy were randomly divided into two groups, the experimental group adopted compositive chest physiotherapy(n = 35), the control group were given the traditional chest physiotherapy(n = 33).The factors considered included the action abide by doctor,the effect of expectoration, the improvement difference of PaO2 ,PaCO2 , SaO2 by blood gas analysis, the incidence of atelectasis.Results There were significant differences in the action abide by doctor and the effect of expectoration. After intervention, the improvement difference of PaO2 ,PaCO2 and SaO2 were significant higher than that of the control group(P <0.05); The rates of atelectasis were 5.71% (2 cases) and 27.27% (9 cases) in experimental group and control group respectively (P < 0.05).Conclusions Compositive chest physiotherapy is superior to traditional physiotherapy for elderly patients in pedoperation, which can clear sputum more effectively, improve blood oxygen partial pressure and lung expansion, also can prevent pest-operative atelectasis more effectively in the elderly patients. Key words: Chest physiotherapy; Elderly patient; Thoracotomy; Rock sputum ejection; Atelectasis

Prevention of Atelectasis in Morbidly Obese Patients during General Anesthesia and Paralysis

Morbidly obese patients show impaired pulmonary function during anesthesia and paralysis, partly due to formation of atelectasis. This study analyzed the effect of general anesthesia and three different ventilatory strategies to reduce the amount of atelectasis and improve respiratory function. Thirty patients (body mass index 45 +/- 4 kg/m) scheduled for gastric bypass surgery were prospectively randomized into three groups: (1) positive end-expiratory pressure of 10 cm H2O (PEEP), (2) a recruitment maneuver with 55 cm H2O for 10 s followed by zero end-expiratory pressure, (3) a recruitment maneuver followed by PEEP. Transverse lung computerized tomography scans and blood gas analysis were recorded: awake, 5 min after induction of anesthesia and paralysis at zero end-expiratory pressure, and 5 min and 20 min after intervention. In addition, spiral computerized tomography scans were performed at two occasions in 23 of the patients. After induction of anesthesia, atelectasis increased from 1 +/- 0.5% to 11 +/- 6% of total lung volume (P < 0.0001). End-expiratory lung volume decreased from 1,387 +/- 581 ml to 697 +/- 157 ml (P = 0.0014). A recruitment maneuver + PEEP reduced atelectasis to 3 +/- 4% (P = 0.0002), increased end-expiratory lung volume and increased Pao2/Fio2 from 266 +/- 70 mmHg to 412 +/- 99 mmHg (P < 0.0001). PEEP alone did not reduce the amount of atelectasis or improve oxygenation. A recruitment maneuver + zero end-expiratory pressure had a transient positive effect on respiratory function. All values are presented as mean +/- SD. A recruitment maneuver followed by PEEP reduced atelectasis and improved oxygenation in morbidly obese patients, whereas PEEP or a recruitment maneuver alone did not.

Intermittent manual positive airway pressure for the treatment and prevention of atelectasis

Intermittent manual positive airway pressure for the treatment and prevention of atelectasis

Prevention of atelectasis during general anaesthesia

Atelectasis is an important cause of impaired gas exchange during general anaesthesia; it causes pulmonary shunting. We studied the effects of gas composition on the formation of atelectasis and on gas exchange during the induction of general anaesthesia. In 12 adult patients, the lungs were ventilated with 30% oxygen in nitrogen during anaesthesia induction, and in another 12, a conventional technique was used (100% oxygen during induction and 40% oxygen in nitrogen thereafter). Extent of atelectasis was estimated by computed tomography and the ventilation-perfusion relation (VA/Q) by the multiple inert gas elimination technique. After anaesthesia induction, there was little atelectasis in the 30% oxygen group (mean 0·2 [SD 0·4] cm2) and a significantly greater amount (4·2 [5·6] cm2; p<0·001) in the 100% oxygen group. Patients in the 30% oxygen group were observed for another 40 min. 6 continued to receive 30% oxygen (subgroup A) and 6 were ventilated with 100% oxygen (subgroup B). During this time, the amount of atelectasis increased to 1·6 (1·6) cm2 in subgroup A and to 4·7 (4·5) cm2 in subgroup B (p=0·047 for difference between groups). In subgroup A, the shunt (VA/Q <0·005) increased from 1·6 (2·0)% of cardiac output to 3·2 (2·7)%, but the arterial oxygen tension did not change. In subgroup B, the shunt increased from 2·6 (5·2)% to 9·8 (5·7)% of cardiac output. These results suggest that the composition of inspired gas is important in atelectasis formation during general anaesthesia. Use of a lower oxygen concentration than is now standard practice might prevent the early formation of atelectasis.

Effects of Lung Surfactant Factor (LSF) Treatment on Gas Exchange and Histopathological Changes in an Animal Model of Adult Respiratory Distress Syndrome (ARDS): Comparison of Recombinant LSF with Bovine LSF

Summary: Repetitive lung lavage of adult rats leads to lung injury similar to ARDS resulting in poor gas exchange, protein leakage and infiltration of polymorphonuclear neutrophils (PMN) into the alveolar spaces (J Appl Physiol 1983; 55: 131-138). In a previous dose response comparison we have demonstrated that poor gas exchange could be improved by lung surfactant factor (LSF) instillation soon after lavage. Since Surfacten® (Tokyo Tanabe Co. Ltd., Tokyo, Japan) was described in vitro to inhibit PMN activity, we compared this preparation with a Recombinant LSF preparation (Byk Gulden, Konstanz, Germany; phospholipids plus human identical surfactant protein C) at doses of 25, 50 and 100 mg/kg body weight. Their efficacy was compared with an untreated control group with respect to improving gas exchange, inhibition of hyaline membrane formation and inhibition of the inflammatory response after multiple lavage. Tracheotomized rats were pressure-controlled ventilated (Siemens Servo Ventilator 900C, Sweden) with 100% oxygen at a respiratory rate of 30 breaths/min, inspiration:expiration ratio of 1:2, peak inspiratory pressure (PIP) of 28 cmH 2O at positive end-expiratory pressure (PEEP) of 8 cmH 2O. Two hours after LSF administration PEEP was reduced from 8 to 6 cmH 2O (first PEEP-reduction), from 6 to 3 (second reduction) and from 3 to 0 cmH 2O (third reduction) and finally raised to 8 cmH 2O. Results for the averaged partial arterial oxygen pressure [PaO 2 (mmHg)] of the 2 h period [PaO 2(5′-120′)] and for the PaO 2 during the second PEEP reduction [PaO 2(PEEP23/3)] were calculated. Both LSF preparations caused a dose-dependent increase of the PaO 2(5′-120′) and the PaO 2(PEEP23/3). Similarly, the formation of hyaline membranes was inhibited by both LSF preparations in a dose-dependent manner. Inhibition of the inflammatory response (infiltration of PMN) was not effected by either of the LSF preparations at any dose level. The described variations in ventilator settings are useful to evaluate the deflation stability and re-expansion potential of different LSF preparations. The reported results give evidence that prevention of atelectasis by LSF treatment improves gas exchange and inhibits formation of hyaline membranes, leading to the conclusion that LSF treatment may be a promising therapy in ARDS patients.

Bronchopulmonary Aspiration

Bronchopulmonary aspiration remains a significant threat to the surgical and intensive care unit patient, and mortality rates for this condition remain high. The key to improvement is prevention. However, if aspiration does occur, early recognition and aggressive treatment will produce the best results. Expeditious intubation, ventilation, removal of particulate matter, prevention of atelectasis, institution of antibiotics, and nutritional support are standards of care.

Liver transplants in children: importance for the otolaryngologist.

Orthotopic liver transplantation (OTLT) for children with end stage liver failure has doubled 1-year survival rates to over 70% with the employment of cyclosporine and prednisone in conjunction with skilled surgical and medical specialists providing supportive care. The otolaryngology service has assisted in the care of 18 of 61 children undergoing OTLT, particularly in managing respiratory problems that required improved pulmonary toilet and prolonged intubation. The prevention of atelectasis of the lung and subsequent sepsis appears to be improved by prompt bronchoscopy.

Postextubation Nasal Continuous Positive Airway Pressure. A Prospective Controlled Study

Nasal continuous positive airway pressure (N-CPAP), applied immediately after extubation, was prospectively evaluated in 18 neonates recovering from respiratory distress syndrome. Patients were randomly assigned to N-CPAP (group 1, N=9) or a control group given oxygen by hood (group 2, N=9). Groups were comparable in birth weight and duration of intubation. In the 24-hour period following extubation, group 1 showed a significantly lower mean respiratory rate (46 +/- 2 vs 74 +/- 4), alveolar-arterial oxygen gradient (94 +/- 9 vs 134 +/- 12 mm Hg), PCO2 (45 +/- 1 vs 50 +/- 1 mm Hg), higher pH (7.33 +/- 0.01 vs 7.30 +/- 0.01), and less atelectasis by roentgenographic scores. This was associated with considerably better clinical courses in group 1 when compared with group 2, in which six patients required a late trial of N-CPAP because of respiratory deterioration and two patients needed reintubation. Postextubation N-CPAP has a striking beneficial effect on respiratory function and prevention of atelectasis.

Pulmonary atelectasis after anaesthesia: pathophysiology and management.

The pathophysiological basis of pulmonary atelectasis is reviewed and risk factors that enhance lung collapse are discussed. Management strategies to reduce or eliminate risk factors and to prevent collapse are discussed and the rational bases of these strategies are identified. Instability of lung alveoli is a consequence of surface tension and regional differences in alveolar size. The inherent tendency of alveoli to collapse is enhanced by the following risk factors; low lung volume, high closing volume, oxygen therapy, a rapid shallow ventilatory pattern, chronic lung disease, smoking, obesity, postoperative pain following abdominal or thoracic surgery, narcotic induced ventilatory depression, and neurological, neuromuscular, muscular and musculoskeletal diseases associated with mechanical impairment of respiratory function. The primary goal of perioperative respiratory management is prevention of atelectasis. Appropriate management strategies include physiotherapy and delay of elective surgery if substantial improvement in respiratory status can be achieved by specific treatments such as antibiotics, bronchodilators, steroids, and reduction of tobacco use and caloric intake. In selected cases, elective postoperative controlled ventilation may be indicated.