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PubMed1991

[Diagnosis of pleural effusions and atelectases: sonography and radiology compared].

In a prospective study it was shown that chest ultrasonography is superior to conventional x-ray diagnosis of recumbent patients in diagnosing pleural effusion and lung atelectasis. In 110 supine radiographs we found a sensitivity of 47% and a specificity of 71% for right pleural effusions and a sensitivity of 55% and a specificity of 93% for left pleural effusions in comparison to 110 sonographic examinations. The results of supine radiographs in detection of atelectasis were less efficient: sensitivity for the right side: 7%; sensitivity for the left side: 13.5%. Hence, the knowledge of chest ultrasonographic diagnosis can improve the interpretation of supine radiographs.

Critical Care↗
PubMed2004

Follow-up of acute pulmonary complications in cystic fibrosis by magnetic resonance imaging: a pilot study.

UNLABELLED: The aim of this pilot study was to obtain information on the value of MRI in the follow-up of atelectasis and pneumonic infiltrates in cystic fibrosis (CF). Six patients aged 5-15 y were initially examined using chest X-ray and magnetic resonance imaging (MRI). Both methods provided identical information. During follow-up, MRI proved suitable to monitor pulmonary complications. CONCLUSION: MRI of the lung is feasible and valuable in the follow-up of atelectasis and pulmonary infiltrates in CF.

Acute Disease↗
PubMed2000

Within-breath arterial PO2 oscillations in an experimental model of acute respiratory distress syndrome.

Tidal ventilation causes within-breath oscillations in alveolar oxygen concentration, with an amplitude which depends on the prevailing ventilator settings. These alveolar oxygen oscillations are transmitted to arterial oxygen tension, PaO2, but with an amplitude which now depends upon the magnitude of venous admixture or true shunt, QS/QT. We investigated the effect of positive end-expiratory pressure (PEEP) on the amplitude of the PaO2 oscillations, using an atelectasis model of shunt. Blood PaO2 was measured on-line with an intravascular PaO2 sensor, which had a 2-4 s response time (10-90%). The magnitude of the time-varying PaO2 oscillation was titrated against applied PEEP while tidal volume, respiratory rate and inspired oxygen concentration were kept constant. The amplitude of the PaO2 oscillation, delta PaO2, and the mean PaO2 value varied with the level of PEEP applied. At zero PEEP, both the amplitude and the mean were at their lowest values. As PEEP was increased to 1.5 kPa, both delta PaO2 and the mean PaO2 increased to a maximum. Thereafter, the mean PaO2 increased but delta PaO2 decreased. Clear oscillations of PaO2 were seen even at the lowest mean PaO2, 9.5 kPa. Conventional respiratory models of venous admixture predict that these PaO2 oscillations will be reduced by the steep part of the oxyhaemoglobin dissociation curve if a constant pulmonary shunt exists throughout the whole respiratory cycle. The facts that the PaO2 oscillations occurred at all mean PaO2 values and that their amplitude increased with increasing PEEP suggest that QS/QT, in the atelectasis model, varies between end-expiration and end-inspiration, having a much lower value during inspiration than during expiration.

Animals↗
PubMed2002

Effect of different pulses of nitric oxide on venous admixture in the anaesthetized horse.

BACKGROUND: Dependent atelectatic lung areas open towards the end of inspiration when the lung opening pressure increases, and recollapse during expiration. We hypothesized that inhaled nitric oxide (NO) counteracts hypoxic vasoconstriction in these collapsing lung areas, resulting in increased pulmonary shunt perfusion. METHODS: We administered NO as a pulse and varied the pulse timing during inspiration in equine anaesthesia, where atelectasis develops regularly. Six spontaneously breathing standard breed trotters were studied under isoflurane anaesthesia in lateral recumbency. NO pulsed into the first 30% of inspiration (group NOp1) was assumed to affect open lung areas. To cover more open lung areas NO was then pulsed into the first 60% of inspiration (group NOp2). In a third group, administration between 50 and 80% of inspiration was aimed at the intermittently opening lung areas (group NOp3). RESULTS: With NOp1, venous admixture decreased by 8 (2)% (mean (SEM), P=0.045) and with NOp2 by 10 (1)% (P=0.01). With NOp3, venous admixture reduction was insignificant. CONCLUSIONS: Pulsed administration of NO in early inspiration is optimal in reducing right to left vascular shunt in atelectatic equine lung. This reduction is positively correlated with the magnitude of the initial shunt. With administration in early inspiration, NO is mostly taken up by the lung. This prevents NO accumulation and NO2 formation in rebreathing circuits. These findings may be important in humans when atelectasis occurs increasingly with overweight and age during anaesthesia, but also in postoperative intensive care and in ARDS.

Anesthesia, Inhalation↗
PubMed2006

The effect of bi-level positive airway pressure mechanical ventilation on gas exchange during general anaesthesia.

BACKGROUND: Atelectasis may occur and ventilation-perfusion mismatch may increase during general anaesthesia with neuromuscular paralysis and mechanical ventilation, though preservation of some intermittent muscle contraction might mitigate this process. There is still no ideal manoeuvre to minimize such mismatch or atelectasis. Bi-level positive airway pressure (BiPAP) ventilation adjusts to extra breaths and improves gas exchange during recovery of diaphragm function after neuromuscular paralysis. We hypothesize that BiPAP ventilation may limit the development of pulmonary shunt and may improve ventilation-perfusion mismatch when compared with standard IPPV, with or without PEEP when neuromuscular paralysis has been used during surgery. METHODS: Twenty ventilated patients either on BiPAP or IPPV with or without PEEP were studied randomly using the multiple inert gas elimination technique (MIGET) at 60 and 120 min after rocuronium at induction and after 60 min. Non-invasive cardiac output (NICO) monitoring and plasma concentrations of rocuronium were measured. We compared the data of MIGET, gas exchange, haemodynamic variables and pulmonary mechanics measurements between the different ventilatory modes. RESULTS: Intrapulmonary shunt (blood flow to V(A)/Q < 0.005) did not increase at 60 min of anaesthesia in any of the different ventilation modes compared with the shunt value before anaesthesia. Log standard deviation of perfusion increased in IPPV, with and without PEEP groups, compared with the baseline (P< 0.05) but did not increase in the BiPAP group. BiPAP ventilation generated a higher level of Pa(O2)than IPPV with or without PEEP (P<0.05). CONCLUSION: BiPAP ventilation was beneficial in decreasing ventilation-perfusion mismatch and improving oxygenation when compared with conventional IPPV (with or without PEEP).

Aged↗
PubMed1997

The effectiveness of incentive spirometry with physical therapy for high-risk patients after coronary artery bypass surgery.

BACKGROUND AND PURPOSE: The purpose of this study was to determine whether the addition of incentive spirometry (IS) to postoperative pulmonary physical therapy is more effective than physical therapy alone in reducing postoperative pulmonary complications in high-risk patients after coronary artery bypass grafting (CABG). Patients were given the spirometer and instructed in its use, as often occurs in clinical settings. SUBJECTS: Patients with chronic airflow limitation following CABG (N = 185) participated. METHODS: Subjects were randomly assigned to receive either postoperative pulmonary physical therapy (breathing exercises, secretion removal, mobility) or physical therapy combined with IS. RESULTS: No difference was found between the two groups in atelectasis, spirometry, oxygen saturation, pulmonary infection, or hospital stay. CONCLUSION AND DISCUSSION: Incentive spirometry combined with physical therapy is no more effective than postoperative physical therapy alone in reducing atelectasis for this population. Use of the spirometer, however, was not monitored, and although the study mimicked practice as it often occurs, the effectiveness of the spirometer cannot be fully evaluated.

Adult↗
PubMed1984

Time course and responses of sustained hypoxic pulmonary vasoconstriction in the dog.

The stability of the pulmonary blood pressure and flow response to alveolar hypoxia (hypoxic pulmonary vasoconstriction or HPV) was studied in six pentobarbital anesthetized, mechanically ventilated open-chested dogs. Aortic and left pulmonary artery blood flows; systemic and pulmonary arterial, central venous, left atrial, and airway pressures; hemoglobin; arterial and mixed venous blood gases were measured. The right lung was ventilated continuously with 100% oxygen, while the left lung was ventilated alternately with 100% O2 ( prehypoxia control phase), an hypoxic gas mixture containing 4% O2, 3% CO2, balance N2 for 4 h, or 100% O2 (post-hypoxia control phase). Hypoxic ventilation of the left lung resulted in an immediate and sustained decrease in left lung blood flow (QL%) from 39.0 +/- 1.8% (mean +/- SE) to 9.9 +/- 3.6% at 15 min of hypoxic ventilation. QL% remained decreased and did not vary significantly during the 4 h of hypoxia. Venous admixture correspondingly was increased and PaO2 decreased by hypoxic ventilation and did not vary significantly during the 4 h of hypoxia. All variables returned to control levels upon reestablishing ventilation with 100% O2. While the maximal reduction in QL% with left lung hypoxic ventilation was identical to that observed during atelectasis previously in our laboratory, the time course of the response was different. The response to hypoxia was maximal by 15 min, however, QL% decreased more slowly during atelectasis, where the maximal reduction was observed by 60 min. The present study therefore demonstrated that hypoxic ventilation of the left lung yielded an immediate and sustained decrease in left lung blood flow for 4 h. The stability of the HPV response probably was accounted for by the lack of such confounding factors as respiratory alkalosis, severe systemic hypoxemia, and increased cardiac output.

Analysis of Variance↗
PubMed1980

The effect of smoke inhalation on pulmonary surfactant.

This paper details efforts to define the primary pathophysiology of acute smoke inhalation without the variables of infection, burns, or fluid resuscitation. A standard dose of smoke (wood and kerosene) was delivered at 37 C to mongrel dogs. The parameters studied included blood gases, carboxyhemoglobin, pulmonary and systemic hemodynamics, respiratory mechanics, surface tension area curves as an indication of surfactant activity, and in vivo photomicroscopy. The FiO2 of the smoke was 17 volumes per cent; the carbon monoxide 17,000 ppm. Immediately following smoke exposure, dense, nonsegmental atelectasis developed. Hemodynamic changes were insignificant, but the PaO2 fell to 49 mmHg; the right to left shunt rose from 5 to 41%. Surfactant reduction was significant: enough to cause an increase in the minimum surface tension from 7 to 22 dynes/cm. This surfactant loss may explain the atelectasis seen and the marked instability of subpleural alveolar walls. The data collected are consistent and support the acute inactivation of surfactant as one of the primary pathophysiologic events in smoke inhalation. The clinical correlation is good; surfactant loss may explain why victims of smoke inhalation are so vulnerable to fluid administration if they have thermal burns as well effectiveness of medical devices.

Animals↗
PubMedDate not supplied

Complications of long tracheostomy tubes.

Complications of long tracheostomy tubes are not generally appreciated. We report three cases which illustrate that long tracheostomy tubes may impinge on the carina or, less commonly, intubate the right main-stem bronchus, with resultant atelectasis of the left lung. Since larger diameter tracheostomy tubes are also longer, they are much more likely than narrow tracheostomy tubes to produce this complication. The tracheostomy tube position should be checked frequently, especially in patients who develop atelectasis and pneumonia of the left lung.

Adolescent↗
PubMedDate not supplied

Balloon catheter re-expansion of atelectatic lung.

Selective re-inflation of the lung with lobar atelectasis was carried out in four patients who were receiving mechanical ventilation. The increased pressure and volume were delivered mainly to the atelectatic lung by momentary obstruction of mainstem bronchus of the uninvolved lung with a balloon-tipped catheter. Blood gases and chest x-rays following the procedure showed improvement in oxygenation with prompt re-expansion of the atelectatic lung. The described procedure is recommended in atelectasis involving major portions of the lung with severe hypoxemia not responding to aggressive conventional treatment.

Adult↗
PubMed2002

Ventilatory care in myasthenia gravis crisis: assessing the baseline adverse event rate.

OBJECTIVE: Myasthenic patients who require mechanical ventilation often develop pneumonia or atelectasis. Although there are differences in the prevalence of these complications among various institutions, there is no evidence that aggressive treatment shortens the course of the myasthenic crisis. We have quantified the severity of lung injury and aggressiveness of respiratory intervention in myasthenic patients admitted to the neuro-critical care unit. DESIGN: We retrospectively identified all mechanically ventilated myasthenic patients admitted in our unit between 1990 and 1998. SETTING: Neuro-critical care unit of a tertiary care center in an urban area with a large, established, regional neuromuscular disease program. PATIENTS: Eighteen myasthenia gravis patients with 24 episodes of respiratory failure requiring mechanical ventilation. INTERVENTIONS: A novel respiratory intervention index, comprising the use of suction, intermittent positive-pressure breathing or bronchodilator treatments, sighs, and chest physiotherapy represented the aggressiveness of the respiratory treatment. The respiratory intervention index was correlated with the lung injury score, used as a measure of lung involvement and other respiratory variables. MEASUREMENTS AND MAIN RESULTS Our patients had less atelectasis and pneumonia than previously published series (46% vs. 91%), leading to shorter mechanical support and neuro-critical care unit stay. The mean respiratory intervention index correlated with lung injury score and inversely with forced vital capacity. CONCLUSIONS: This study presents an estimate for both severity of pulmonary complications and intensity of respiratory therapy in the severe myasthenic patient with mechanical ventilatory compromise. Our results suggest that aggressive respiratory treatment should be used in myasthenic patients in crisis to diminish the risk for prolonged respiratory complications. These observations should be validated in a prospective study.

Aged↗
PubMed1994

Receiver operating characteristic evaluation of computer display of adult portable chest radiographs.

RATIONALE AND OBJECTIVES: The suitability of using an image console monitor for interpretation of adult portable chest radiographs was evaluated with receiver operating characteristic (ROC) analysis and subjective techniques. METHODS: Radiologists read 80 chest images, once on a display monitor and once on computed radiography film, for the presence or absence of pneumothorax or atelectasis. Judgments of correct or incorrect positions of tubes and lines were reported, and total viewing time was recorded. RESULTS: A statistically significant difference was found in favor of monitor reading for detection of pneumothoraces. Atelectasis detection also was higher with monitor reading, but the difference did not reach statistical significance. Tube/line judgments were equivalent for both modes. Total viewing time was approximately 1 minute longer per image with the monitor. CONCLUSIONS: Viewing computed radiography images on a workstation monitor does not seem to affect diagnostic accuracy compared with film viewing. Preset image defaults tailored to the individual radiologist could decrease total viewing time to acceptable levels.

Adult↗
PubMedDate not supplied

Lower lobe collapse due to pleural effusion: a CT analysis.

In the presence of a pleural effusion, volume loss is seen in the adjacent lung, primarily in the lower lobe. With a modest effusion a compliant lower lobe may show displacement and generalized volume loss without focal atelectasis, but more commonly segmental atelectasis does occur, typically in the posterior basal segment. Large effusions result in a major degree of lower lobe collapse. The collapsed lobe tends to be uplifted by the fluid and compressed toward the hilum with consequent stretching and attenuation of the inferior pulmonary ligament, rather than collapsing posteriorly and medially.

Adult↗
PubMedDate not supplied

Necrotizing Aspergillosis of large airways: CT findings in eight patients.

PURPOSE: The aim of this study was to evaluate the CT findings of pathologically proven necrotizing aspergillosis of the large airways (necrotizing Aspergillus bronchitis). METHOD: Medical records and imaging studies from two tertiary medical centers were reviewed for pathologically proven cases of necrotizing aspergillosis of the large airways. Fiberoptic bronchoscopic examination and CT scans of the chest were available in all cases. Two thoracic radiologists who were blinded to the clinical and pathologic data reviewed the thoracic CT scans retrospectively and reached a final decision. The CT images were evaluated for the presence, distribution, and extent of CT findings. RESULTS: The study included eight patients, seven men and one woman, ranging in age from 28 to 67 years (mean age 46 years). All patients had histopathologically proved necrotizing Aspergillus of the large airways and no other superimposed infections. Six patients had leukemia, one had chronic liver disease, and one had chronic obstructive lung disease. All patients had bronchial wall thickening and focal bronchial narrowing involving a lobar or segmental bronchus. The bronchial narrowing was irregular or nodular in seven patients and smooth in one. Atelectasis distal to a narrowed bronchus was present in five patients. CONCLUSION: The CT findings of necrotizing bronchial aspergillosis include bronchial wall thickening, which is often nodular, and narrowing of the bronchial lumen, which is often associated with distal atelectasis.

Adult↗
PubMed2000

Effects of fiberoptic bronchoscopy on intracranial pressure in patients with brain injury: a prospective clinical study.

BACKGROUND: Fiberoptic bronchoscopy (FB) plays an important role in making the diagnosis of nosocomial pneumonia and resolving lobar atelectasis in critically injured trauma patients. It has been shown to be a safe procedure with only occasional complications. However, in patients with head injuries, FB can lead to intracranial hypertension. Sustained increases in intracranial pressure (ICP) leads to poor outcome in these patients. Because of this, a prospective study was done not only to assess the effect of FB on ICP and cerebral perfusion pressure (CPP) in patients with brain injuries, but also to identify a regimen of sedation and anesthesia that could prevent significant increases in ICP during FB. METHODS: Twenty-six FB were performed in 23 patients with ICP monitors or ICP monitors and ventriculostomy drains in place for Glasgow Coma Scale score < 8 or management of postcraniotomy trauma. FB was performed to aid in the diagnosis of nosocomial pneumonia or to aid in resolving lobar atelectasis. Before FB, all patients received a standard anesthetic regimen consisting of vecuronium (10 mg), morphine sulfate (4 mg), and midazolam (2.5 mg). Patients with diminished cranial compliance, defined as ICP > 10 mm Hg, also received a nebulizer treatment of 3 mL of 4% lidocaine before FB. All patients were preoxygenated with FIO2 = 1.0 for 10 minutes. Intracranial pressure, mean arterial pressure, and CPP were monitored continuously throughout the procedure. These same variables were also recorded at baseline and at 2-minute intervals during the procedure. The time to return to baseline ICP was also recorded. RESULTS: The mean ICP at baseline (immediately before FB) was 12.6 mm Hg. After introduction of the bronchoscope, the ICP rapidly increased in 21 procedures (81%) and the mean highest ICP was 38.0 mm Hg. There was also a concomitant increase in mean arterial pressure such that there was no substantial change in CPP. The mean lowest CPP was 73.1 mm Hg. The average time for return of ICP to baseline was 13.9 minutes. In the subgroup of patients with ICP > 10, attempting to blunt the tracheal stimulation by anesthetizing the trachea with 4% nebulized lidocaine did not seem to be successful. The mean highest ICP in this subgroup was 41.8 mm Hg. The CPP changed in a similar manner, as the mean lowest CPP was 74.0 mm Hg. The mean time to return to baseline was 12.5 minutes. No patient had acute neurologic deterioration secondary to FB. CONCLUSIONS: Although FB is an important procedure in the pulmonary care of head injured patients, it produces substantial, but transient, increases in ICP and should be used with caution in patients with diminished cranial compliance. Sedation, analgesia, paralysis, and topical tracheal anesthesia did not completely prevent the rise in ICP. Although no acute deterioration in condition occurred, secondary brain injury caused by localized cerebral ischemia is certainly possible. Because of the substantial increases in ICP, herniation may be precipitated in an occasional patient. Further study is needed to identify a regimen that will confer protection.

Adolescent↗
PubMed1991

Differentiation of bronchogenic carcinoma from postobstructive pneumonitis by magnetic resonance imaging: histopathologic correlation.

Obstructive pneumonitis frequently occurs distal to hilar bronchogenic carcinomas or in lung adjacent to peripheral tumors. The article evaluates the role of MRI in the differentiation of tumor from pneumonitis. Twelve patients underwent MRI of the thorax before surgery. T1-weighted (SE 310/20) and T2-weighted (SE 2000/60-120) images were obtained through the tumor and presumed areas of pneumonitis. Five histologic types of pneumonitis were identified on pathologic examination of the 12 specimens. Cholesterol pneumonitis, found in 7 patients, was the most common type. Organizing pneumonitis, bronchiectasis with mucus plugs, atelectasis, and abscess were found in 3, 4, 2, and 1 patients, respectively. MRI was able to differentiate tumor from pneumonitis in 5 of 6 patients with a hilar mass and in 5 of 6 patients with a peripheral tumor. This was achieved by a visual difference in signal intensity on heavily T2-weighted (SE 2000/120) images. Cholesterol pneumonitis and bronchiectasis with mucus plugs were always hyperintense relative to tumor, and organizing pneumonitis and atelectasis were isointense and indistinguishable from tumor. MRI can differentiate tumor from pneumonitis provided that pneumonitis is of the cholesterol type or if there are mucus plugs in the collapsed lung.

Aged↗
PubMed1991

Differentiation of central lung tumor from postobstructive lobar collapse by rapid sequence computed tomography.

When central lung tumor is associated with lobar collapse, discrimination of tumor from atelectasis is important for determining operability or for field planning should radiation therapy be utilized. Because tumor and collapsed lung have similar attenuation values, they cannot always be distinguished with usual contrast-enhanced CT. The article describes separation of tumor from collapsed lung by means of RSCT with bolus injection of nonionic contrast medium. With this technique collapsed lung is appreciably enhanced, but tumor enhancement is slow and minimal. The difference is most marked from 40 seconds to 2 minutes after scanning begins. This phenomenon is probably related to the marked increase in blood flow per unit area of collapsed lung due to crowding of relatively large pulmonary arteries compared to tumor blood supply through small bronchial arteries. Tumor can also be delineated from atelectasis by differences in internal structure with this technique.

Aged↗
PubMed2002

Pulmonary function after pectoralis major myocutaneous flap harvest.

OBJECTIVE: The pectoralis major myocutaneous flap is widely used in the reconstruction of surgical defects in the head and neck region. Pulmonary atelectasis has been reported in patients undergoing these procedures, and many of these patients are heavy smokers and drinkers and have associated cardiopulmonary disorders. Flap harvest and donor site closure may lead to impairment of pulmonary function before and after the use of pectoralis major myocutaneous (PMC) in surgical reconstruction in patients with cancer of the head and neck. METHODS: Patients undergoing extirpation of head and neck tumors with PMC reconstruction were prospectively evaluated. Patient age, smoking history (pack-years), anesthesia duration, percentage predicted pre- and postoperative FEV1, percentage-predicted pre- and postoperative FVC (forced vital capacity), and preoperative SaO2 (oxygen saturation) were evaluated. Preoperative FEV1/FVC ratio was calculated. Chest x-rays were reviewed. RESULTS: Only 11 patients, 5 of whom smoked, could be evaluated postoperatively. Preoperative FEV1/FVC was more than 70 and FEV1 more than 75% predicted in all patients. A decrease in FVC was observed in 7 of the 11 patients, which ranged between 2% and 27% without any clinically obvious respiratory manifestations. A baseline SaO2 of more than 96% was noted in all patients. Four of 9 postoperative chest x-rays demonstrated atelectasis. CONCLUSIONS: PMC harvest and donor site closure may lead to the recorded decrease in FVC measurements. These changes did not manifest clinically. Nevertheless, alternative methods of surgical defect closure should be considered in patients with severe preexisting pulmonary disorders.

Aged↗