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Value of body plethysmography in preoperative assessment of thoracotomy candidates.

The usefulness of body plethysmography in the assessment of thoracotomy candidates is not well documented. Reported thresholds for operability are generally expressed in absolute values, which do not take into account a patient's size, age or gender. Spirometric and plethysmographic data of 103 patients undergoing thoracotomy were examined for their ability to predict death due to cardiopulmonary insufficiency, pneumonia, and atelectasis during the first 30 postoperative days. Neither plethysmographic nor spirometric parameters could predict atelectasis. Patients who underwent lobectomy were susceptible to the development of atelectasis. A weak correlation between elevated functional residual capacity (FRC) and occurrence of postoperative pneumonia was found. Lung function testing was not able to separate survivors from non-survivors. Patients with pneumonia were at high risk of death in their postoperative course. Because of the non-linear relationship, a correlation coefficient between spirometric and plethysmographic variables was not calculated. The prevalence of cardiac risk factors was high, so the decision for invasive hemodynamic studies should rather be based upon a patient's history than restricted to patients with impaired lung function. Because of methodological differences, and probably insuitable reference values, body plethysmography cannot substitute for spirometry. For FRC and FRC to total lung capacity (FRC/ TLC) ratio, further investigations must be undertaken to establish a correct reference value.

Adult↗

Respiratory outcomes with early extubation after coronary artery bypass surgery.

OBJECTIVE: Aortocoronary bypass surgery has undergone recent changes, promoting the concept of "fast tracking," in which patients are extubated and discharged postoperatively at an accelerated pace compared with previous historic patterns. Postoperative respiratory function and complications have not been previously studied in patients selected for "fast tracking." DESIGN: Matched retrospective cohort study. SETTING: Referral university teaching hospital. PATIENTS: Thirty-one patients who were compared with a retrospective matched cohort of 112 patients. Matching was based on forced vital capacity, age, and gender. INTERVENTIONS: Respiratory physiological outcomes defined as pneumonia, postoperative pulmonary spirometry, chest x-ray atelectasis or lobar collapse, and gas exchange were compared. MAIN RESULTS: The increase in atelectasis score compared with preoperative (0 = no atelectasis, 4 = lobar collapse) was higher (p < 0.01) on the day of extubation in the late extubation group (4.1 +/- 1.4) compared with the early extubation group (2.6 +/- 1.3). These chest radiographic findings were not related to pain (0 to 10 visual analog scalei, which were equivalent between groups (4.0 +/- 2.3 v 4.2 +/- 1.6). The decreases in spirometry on postoperative day 5 (FVC 1.15 +/- 0.42 v 0.86 +/- 0.54 liters; FEV1 0.92 +/- 0.38 v 0.59 +/- 0.50 liters) were greater (p < 0.001) in the late extubation group. A significantly (p < 0.001) greater decrease in FEV1/FVC ratio in the late extubation group (3.25 +/- 0.87 v -1.6 +/- 1.11%) was indicative of greater airway obstruction. Fluid balance until extubation was greater in the late extubation group (4.0 +/- 2.1 v 1.4 +/- 1.2 liters). CONCLUSIONS: Differences in chest radiographs in the late extubation group at the time of extubation may be related to greater use of fluids or increased airway obstruction. The rationale of early extubation is based on cost minimization to decrease hospital duration. This article suggests that respiratory physiological outcomes are not worsened in patients who are extubated and discharged early after elective aortocoronary bypass surgery.

Airway Obstruction↗

How to inform a morbidly obese patient on the specific risk to develop postoperative pulmonary complications using evidence-based methodology.

BACKGROUND AND OBJECTIVE: Patients have the right to be informed about the expected benefits and risks of medical and surgical procedures. Ideally this information should be scientifically based and presented to the patient in time. In morbidly obese patient undergoing general anaesthesia, postoperative pulmonary complications are an important cause of postoperative morbidity and mortality. A 46-yr-old female with a body mass index of 89.8 kg m(-2) was scheduled to undergo radical abdominal surgery for cervix carcinoma. In order to inform her accurately on the risk of developing postoperative pulmonary complications, we undertook to answer the following question: What is the risk to develop postoperative pulmonary complications in a morbidly obese patient about to undergo abdominal surgery under general anaesthesia? METHODS: A Medline search was conducted from 1966 to 2004 with respect to postoperative pulmonary complications in abdominal surgery of morbidly obese patients. Altogether, 213 articles were found, of which seven were selected. Additionally, seven cross-references and or related articles were used. RESULTS: For obese patients who undergo abdominal surgery under general anaesthesia, the likelihood to develop atelectasis is 10.4 +/- 4.8% (P < 0.001) with a correlation coefficient of 0.28-0.34 (P < 0.05). The likelihood to develop atelectasis and pneumonia taken together is 29.3% with an adjusted odds ratio of 2.82 (95% confidence interval 1.66-4.78; P = 0.0001). CONCLUSION: Considering the positive correlation coefficient and the high body mass index of this patient she has a risk of at least 29.3% to develop pneumonia and/or atelectasis, which should affect the anaesthetic strategy in this patient.

Anesthesia, General↗

Supplemental oxygen is not required in trauma patients treated with IV opiates.

The risk of respiratory depression can prevent the proper use of opioids in trauma patients and lead to use of supplemental oxygen. However, high FiO(2) might contribute to atelectasis formation and consequently to relative hypoxia. Supplemental oxygen also can cause a risk of fire. In a randomized, controlled study we evaluated the need and effects of supplemental oxygen in 13 patients with extremity trauma who were treated pain-free with an intravenous opioid, oxycodone (dose range 6.75-13.6 mg). After opioid injection, 7 patients received 40% supplemental oxygen and 6 were breathing room air. Pulse oxygen saturation (SpO(2)), arterial blood gases, and hemodynamic parameters were monitored for 30 minutes. Atelectasis formation was evaluated with a computed tomography scan. No hypoxia, hypoventilation, or significant atelectasis formation was detected in any of the patients. Accordingly, routinely given supplemental oxygen was not considered necessary in these patients because no complications were seen.

Adult↗

Repeated endotracheal intubations and bronchial lavage in the postoperative treatment of tracheoesophageal fistula.

Recurrent pulmonary atelectasis occurs often in neonates following primary repair of esophageal atresia, leading to massive pneumonia and respiratory failure. The atelectasis is caused by tenacious mucous plugs which are presumably formed as a result of ciliary mucosal damage secondary to reflux of gastric fluid through a tracheo-esophageal fistula. Early aggressive treatment of the atelectasis by repeated gentle tracheal intubation with bronchial lavage and suction is advocated. This treatment is well tolerated and is preferred to continuous intubation with its inherent dangers for the neonatal patient.

Bronchoscopy↗

Incentive spirometry to prevent acute pulmonary complications in sickle cell diseases.

BACKGROUND: This study was designed to determine the incidence of thoracic bone infarction in patients with sickle cell diseases who were hospitalized with acute chest or back pain above the diaphragm and to test the hypothesis that incentive spirometry can decrease the incidence of atelectasis and pulmonary infiltrates. METHODS: We conducted a prospective, randomized trial in 29 patients between 8 and 21 years of age with sickle cell diseases who had 38 episodes of acute chest or back pain above the diaphragm and were hospitalized. Each episode of pain was considered to be an independent event. At each hospitalization, patients with normal or unchanged chest radiographs on admission were randomly assigned to treatment with spirometry or to a control nonspirometry group. Each patient in the spirometry group took 10 maximal inspirations using an incentive spirometer every two hours between 8 a.m. and 10 p.m. and while awake during the night until the chest pain subsided. A second radiograph was obtained three or more days after admission, or sooner if clinically necessary, to determine the incidence of pulmonary complications. Bone scanning was performed no sooner than two days after hospital admission to determine the incidence of thoracic bone infarction. RESULTS: The incidence of thoracic bone infarction was 39.5 percent (15 of 38 hospitalizations). Pulmonary complications (atelectasis or infiltrates) developed during only 1 of 19 hospitalizations of patients assigned to the spirometry group, as compared with 8 of 19 hospitalizations of patients in the nonspirometry group (P = 0.019). Among patients with thoracic bone infarction, no pulmonary complications developed in those assigned to the spirometry group during a total of seven hospitalizations, whereas they developed during five of eight hospitalizations in the nonspirometry group (P = 0.025). CONCLUSIONS: Thoracic bone infarction is common in patients with sickle cell diseases who are hospitalized with acute chest pain. Incentive spirometry can prevent the pulmonary complications (atelectasis and infiltrates) associated with the acute chest syndrome in patients with sickle cell diseases who are hospitalized with chest or back pain above the diaphragm.

Acute Disease↗

Randomized controlled trial of physiotherapy for postoperative pulmonary complications.

A prospective randomized controlled trial was conducted in patients undergoing elective cholecystectomy to assess the value of routine chest physiotherapy. One hundred and two patients entered the study: 47 patients developed no pulmonary complications, 29 had pulmonary atelectasis and a further 26 developed chest infection. The pattern of changes in arterial oxygen tension in the period after operation supported the clinical allocation of the patients. Of 51 patients not receiving physiotherapy, 11 developed atelectasis and 19 chest infection. Of 51 treated patients, 18 developed atelectasis and seven chest infection. Routine prophylactic postoperative chest physiotherapy decreased significantly the frequency of chest infection (P less than 0.02).

Adult↗

Repeated vital capacity manoeuvres after cardiopulmonary bypass: effects on lung function in a pig model.

Respiratory failure following cardiopulmonary bypass (CPB) is a major complication after cardiac surgery. A vital capacity inflation of the lungs, performed before the end of CPB, may improve gas exchange, but the necessity to repeat it is unclear. Therefore, we studied 18 pigs undergoing hypothermic CPB. A vital capacity manoeuvre (VCM) was performed in two groups and consisted of inflating the lungs for 15 s to 40 cm H2O at the end of CPB. In one group, VCM was repeated every hour. The third group served as controls. Atelectasis was studied by CT scan. Intrapulmonary shunt increased after bypass in the controls and improved spontaneously 3 h later without returning to baseline values. From 3 to 6 h after CPB, there was no more improvement and more than 10% atelectasis remained at 6 h. In contrast, the two groups treated before termination of CPB with VCM showed only minor atelectasis and no abnormal changes in gas exchange directly after bypass or later. We conclude that the protective effect of VCM remained for 6 h after bypass, and there was no extra benefit on gas exchange by repeating the VCM.

Animals↗

Variation of venous admixture, SF6 shunt, PaO2, and the PaO2/FIO2 ratio with FIO2.

BACKGROUND: Measures of impairment of oxygenation can be affected by the inspired oxygen fraction. METHODS: We used a mathematical model of an inhomogenous lung to predict the effect of increasing inspired oxygen concentration (FIO2) on: (1) venous admixture (Qva/Qt); (2) arterial oxygen partial pressure (PaO2); (3) the PaO2/FIO2 index of hypoxaemia; and (4) sulphur hexafluoride (SF6) retention (often taken to be true right-to-left shunt). This model predicts whether or not atelectasis will occur. RESULTS: For lungs with regions of low V/Q, increasing the inspired oxygen concentration can cause these regions to collapse. In the absence of atelectasis, the model predicts that Qva/Qt will decrease and arterial oxygen partial pressure increase as FIO2 is increased. However, when atelectasis occurs, Qva/Qt rises to a constant value, whilst PaO2 falls at first, but then begins to rise again, with increasing FIO2. The SF6 retention increased markedly in some cases at high FIO2. CONCLUSIONS: Venous admixture will estimate true right-to-left shunt at high FIO2, even when oxygen consumption is raised. This model can explain the way that the Pa/Fl ratio changes with increasing inspired oxygen concentration.

Computer Simulation↗

The comparative effects of postoperative analgesic therapies on pulmonary outcome: cumulative meta-analyses of randomized, controlled trials.

UNLABELLED: We performed meta-analyses of randomized, control trials to assess the effects of seven analgesic therapies on postoperative pulmonary function after a variety of procedures: epidural opioid, epidural local anesthetic, epidural opioid with local anesthetic, thoracic versus lumbar epidural opioid, intercostal nerve block, wound infiltration with local anesthetic, and intrapleural local anesthetic. Measures of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), vital capacity (VC), peak expiratory flow rate (PEFR), PaO2, and incidence of atelectasis, pulmonary infection, and pulmonary complications overall were analyzed. Compared with systemic opioids, epidural opioids decreased the incidence of atelectasis (risk ratio [RR] 0.53, 95% confidence interval [CI] 0.33-0.85) and had a weak tendency to reduce the incidence of pulmonary infections (RR 0.53, 95% CI 0.18-1.53) and pulmonary complications overall (RR 0.51, 95% CI 0.20-1.33). Epidural local anesthetics increased PaO2 (difference 4.56 mm Hg, 95% CI 0.058-9.075) and decreased the incidence of pulmonary infections (RR 0.36, 95% CI 0.21-0.65) and pulmonary complications overall (RR 0.58, 95% CI 0.42-0.80) compared with systemic opioids. Intercostal nerve blockade tends to improve pulmonary outcome measures (incidence of atelectasis: RR 0.65, 95% CI 0.27-1.57, incidence of pulmonary complications overall: RR 0.47, 95% CI 0.18-1.22), but these differences did not achieve statistical significance. There were no clinically or statistically significant differences in the surrogate measures of pulmonary function (FEV1, FVC, and PEFR). These analyses support the utility of epidural analgesia for reducing postoperative pulmonary morbidity but do not support the use of surrogate measures of pulmonary outcome as predictors or determinants of pulmonary morbidity in postoperative patients. IMPLICATIONS: When individual trials are unable to produce significant results, it is often because of insufficient patient numbers. It may be impossible for a single institution to study enough patients. Meta-analysis is a useful tool for combining the data from multiple trials to increase the patient numbers. These meta-analyses confirm that postoperative epidural pain control can significantly decrease the incidence of pulmonary morbidity.

Administration, Oral↗

An evaluation of incentive spirometry in the management of pulmonary complications after cardiac surgery in a pediatric population.

Changes in pulmonary function and the development of atelectasis in the postoperative period have been well documented in the adult population. The use of incentive spirometry has been shown to be effective in the prevention of these postoperative complications. At the Hospital of Sick Children, we studied 17 children (8 control and 9 study) to determine if the same trends occurred. Baseline and follow-up roentgenograms and pulmonary function tests (PFTs) were documented for both groups. In addition, the study group followed the protocol for incentive spirometry. There was significantly less atelectasis in the study group (33%) than in the control group (88%). There was a significant loss of pulmonary function postoperatively in both groups. However, there were no statistically significant differences between the groups either in the degree of pulmonary function loss postoperatively or in the recovery baseline pulmonary function to discharge. We conclude that incentive spirometry is as effective in reducing the incidence of atelectasis in children undergoing cardiac surgery as in adults.

Adolescent↗

Influence of the method of re-expansion of atelectatic lung upon the development of pulmonary edema in dogs.

An endobronchial tube was used to separately ventilate each lung in anesthetized dogs, and absorption atelectasis was then induced in the left lung and maintained for 3 1/2 h. The left lung was partially re-expanded by ventilation at normal tidal volumes for 10 min, and then completely re-expanded by manual hyperinflation. This delayed re-expansion was associated with an extravascular water content significantly greater than that of the right lung. A previous study demonstrated no increase in the ratio of left to right lung water content after 3 h of atelectasis alone and a significant increase after immediate hyperinflation. Delayed re-expansion produces significantly different results, and it is therefore concluded that the method of lung re-expansion influences the development of pulmonary edema after atelectasis.

Animals↗

Effect of high-frequency positive-pressure ventilation on halothane ablation of hypoxic pulmonary vasoconstriction.

High-frequency positive-pressure ventilation (HFPPV) was compared to intermittent positive-pressure ventilation (IPPV) during unilateral atelectasis with and without halothane anesthesia. Dogs with electromagnetic flow probes chronically implanted on their main (Qt) and left (Ql) pulmonary arteries were ventilated via Carlen's dual-lumen endotracheal tubes. In eight closed-chest dogs, about 43% of the cardiac output perfused the left lung during bilateral ventilation by either a Harvard animal respirator (IPPV) or a Health-dyne model 300 high-frequency ventilator (HFPPV). Unilateral atelectasis decreased blood flow (Ql/Qt) to that lung. Ql/Qt was 19 +/- 1% with HFPPV during left-lung atelectasis and right-lung ventilation, compared to 32 +/- 1% with unilateral IPPV. This suggests that HFPPV permits stronger hypoxic pulmonary vasoconstriction. Addition of 1% halothane increased blood flow to the atelectatic left lung during unilateral ventilation with IPPV but not with HFPPV. This suggests that halothane decreases the effects of hypoxic pulmonary vasoconstriction during conventional ventilation but not during HFPPV.

Animals↗

Effect of a rotating bed on the incidence of pulmonary complications in critically ill patients.

The risk of nosocomial pneumonia and atelectasis is high among critically ill immobilized patients. We hypothesized that continuous turning on the kinetic treatment table would reduce their incidence. Sixty-five critically ill patients, immobilized because of head injury or traction, were prospectively randomized for treatment in a conventional bed (n = 38) or the kinetic treatment table (n = 27). Patients were well matched for baseline demographic and pulmonary risk factors. Patients in the conventional bed group had a higher incidence of cigarette smoking. The combined incidence of significant atelectasis or pneumonia was higher (66%) in the conventional vs. kinetic treatment table (33%) groups (p less than .01). Atelectasis, pneumonia, adult respiratory distress syndrome, requirements for ventilator treatment, for PEEP, and for an FIO2 greater than 0.50 were not significantly different, but tended to be higher in the control group. Survival and the incidence of decubitus ulcers were similar.

Adult↗

Computed tomography of lobar collapse: 2. Collapse in the absence of endobronchial obstruction.

The computed tomographic appearance of collapse without endobronchial obstruction is reviewed. These 57 cases were classified by the etiology of collapse. The largest group consisted of 29 patients with passive atelectasis, i.e., collapse secondary to fluid, air, or both in the pleural space. Twenty-three of 29 proved secondary to malignant pleural disease. Computed tomography accurately predicted a malignant etiology in 22 of 23 cases. The second largest group of patients had lobar collapse secondary to cicatrization from chronic inflammation. In all cases the underlying etiology was tuberculosis. Radiation caused adhesive atelectasis in six patients secondary to a lack of production of surfactant. In each case a sharp line of demarcation could be defined between normal and abnormal collapsed pulmonary parenchyma. Three cases of unchecked tumor growth caused a peripheral form of collapse (replacement atelectasis). This form of collapse was characterized by an absence of endobronchial obstruction and extensive tumor not delineated by the normal boundaries of the pulmonary lobes.

Cicatrix↗

Effect of CPAP during cardiopulmonary bypass on postoperative lung function. An experimental study.

BACKGROUND: Respiratory failure secondary to cardiopulmonary bypass (CPB) remains a major complication after cardiac surgery. We tested the hypothesis that post-CPB lung function impairment can be prevented by continuous positive airway pressure (CPAP) applied during the CPB. METHODS: In 6 pigs, CPAP with 5 cmH2O pressure was applied during CPB. Six other pigs served as control, i.e. the lungs were open to the atmosphere during CPB. After median sternotomy, the right atrial appendage as well as the ascending aorta were cannulated. The total CPB duration was 90 min with 45 min cardioplegic arrest. Ventilation-perfusion distribution was measured with the multiple inert gas elimination technique and atelectasis by CT-scanning. RESULTS: Large atelectasis appeared after CPB, corresponding to 14.5% +/- 5.5 (percent of the total lung area) in the CPAP group and 18.7% +/- 5.2 in the controls (P = 0.20). Intrapulmonary shunt increased and PaO2 decreased after the CPB in both groups. CONCLUSIONS: We conclude that in this pig model post-CPB atelectasis is not effectively prevented by CPAP applied during CPB.

Airway Resistance↗

Asbestos-related focal lung masses: manifestations on conventional and high-resolution CT scans.

In 260 asbestos-exposed individuals evaluated by means of computed tomography (CT), 43 unsuspected pulmonary masses were found in 27 individuals. The masses included fissural pleural plaques (n = 10), dense fibrotic bands (n = 3), round atelectasis (n = 11), carcinomas (n = 3), and other presumed benign masses (n = 16). The most helpful features in the diagnosis of rounded atelectasis with CT were (a) contiguity to areas of diffuse pleural thickening, (b) a lentiform or wedge-shaped outline, (c) evidence of volume loss in the adjacent lung, and (d) a characteristic "comet tail" of vessels and bronchi sweeping into the margins of the mass. Less advanced areas of focal atelectasis had fewer classic features. Intrafissural pleural plaques were readily identified with high-resolution CT. In asbestos-related masses, the demonstration of stability over time is necessary. Careful interpretation of CT and high-resolution CT features and close surveillance can obviate the need for biopsy in the majority of instances.

Asbestos↗

Mechanism of change in pulmonary shunt flow with hemorrhage.

In the presence of regional atelectasis, hemorrhage increases the pulmonary shunt fraction (Qs/Qt). We wanted to determine if the increase in Qs/Qt occurs due to inhibition of hypoxic vasoconstriction or due to hydrostatic effects associated with a collapsed lung and decrease in cardiac output. We compared the effects of hemorrhage on flow to a hypoxic lung (Qh) produced in two ways in anesthetized dogs. In six dogs atelectasis of one lung was produced by bronchial occlusion and in a second group of six dogs one lung was ventilated with 100% nitrogen. The other lung in each group was ventilated with 100% nitrogen. The other lung in each group was ventilated with 100% O2. Hemorrhage (20 ml/kg) had no effect on Qh/Qt in dogs with a nitrogen-ventilated lung suggesting that hemorrhage did not inhibit hypoxic vasoconstriction. In contrast, hemorrhage caused a marked increase in Qh/Qt in dogs with a collapsed lung because the flow to the inflated ventilated lung fell, while flow to the collapsed lung did not change. The increase in Qs/Qt in the dogs with atelectasis can be explained solely on the basis of mechanical effects produced by the differences in lung heights and alveolar pressures between ventilated and atelectatic lung.

Animals↗