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PubMed1996

Lung hyaluronan decreases during group B streptococcal pneumonia in neonatal piglets.

Neonatal Group B streptococcus (GBS) sepsis and pneumonia result in lung injury and remain a major cause of morbidity and mortality in the newborn. Increased lung hyaluronan (HA) content is an important component of the lung's early response to damage in diseases such as adult respiratory distress syndrome (ARDS), infant respiratory distress syndrome (IRDS), and bleomycin-induced fibrosis. It is known, however, that GBS virulence factors include specific secretory enzymes such as hyaluronidase, an enzyme which breaks down HA. We therefore hypothesized that in lobar GBS pneumonia, lung HA would be decreased compared with normal values, and that in lobar pneumonia with atelectasis, lung HA would be further decreased because of increased substrate availability. The right lower lobes (RLL) and left lower lobes (LLL) of anesthetized piglets 16 +/- 2 d old were each selectively inoculated with 1 x 10(9) colony-forming units (CFU) GBS via an endobronchial catheter (n = 7). The LLL was subsequently collapsed by endobronchial occlusion following 10 min of 100% O2. Control animals (n = 6) was anesthetized, instrumented, and ventilated without exposure to GBS. At 4 h, lungs were removed and HA extracted and assayed using a competitive inhibition assay. HA extracted from areas of lobar pneumonia was significantly decreased (27 +/- 6.6 micrograms/g wet lung, p < 0.005) when compared with control values of control piglets (51 +/- 19.6 micrograms/g wet lung). Atelectasis plus lobar pneumonia further decreased lung HA to 10 +/- 13.3 micrograms/g wet lung, p < 0.0001. We conclude that lobar GBS decreases lung HA and that this process is augmented by collapsed lung regions, and speculate that this departure from the usual early lung response to injury contributes to GBS invasion of lung parenchyma.

Animals↗
PubMed1998

Effect of different pressure levels on the dynamics of lung collapse and recruitment in oleic-acid-induced lung injury.

The effects of different inspiratory and expiratory airway pressures (Paw) on the dynamics of lung collapse and recruitment were studied in 14 anesthetized, mechanically ventilated, pigs with oleic-acid-induced lung injury. Repetitive CT scans of the same slice were obtained every 0.8 s during different inspiration and expiration hold procedures. The mean lung density and amount of atelectasis were measured in each scan. Inspiration to a Paw of 15 cm H2O above PEEP resulted in recruitment of collapsed lung tissue, mainly within 1.4 s. During expiration lung density increased rapidly and at an almost even rate within the first 1.4 s, whereas a rapid increase of atelectasis occurred after an initial delay period of 0.6 s with PEEP = 10 or 15 cm H2O. PEEP of 20 or 25 cm H2O almost prevented lung collapse during expiration. Thus, in order to avoid cyclic alveolar collapse during mechanical ventilation in oleic-acid-induced lung injury, a PEEP level >= 20 cm H2O or an expiration time <= 0.6 s is required. Long inspiratory time intervals, as used in inverse ratio ventilation, seem to be of minor importance for the recruitment of collapsed lung tissue in this experimental model.

Analysis of Variance↗
PubMed1988

Lung volume maintenance prevents lung injury during high frequency oscillatory ventilation in surfactant-deficient rabbits.

Controversy exists whether high frequency oscillatory ventilation with an active expiratory phase (HFO-A) should be used at low ventilator pressures or high alveolar volumes to minimize lung injury in the atelectasis-prone lung. We therefore ventilated 20 anesthetized, tracheostomized rabbits made surfactant-deficient by lung lavage in 1 of 3 ways: HFO-A at a high lung volume (HFO-A/HI), HFO-A at a low lung volume (HFO-A/LO), or conventional mechanical ventilation (CMV); all received 100% oxygen for 7 h. We examined oxygenation, lung mechanics, and lung pathology. Arterial oxygenation in the HFO-A/HI rabbits was kept greater than 350 mm Hg. Mean lung volume above FRC in these animals was 23.4 ml/kg. In rabbits ventilated with HFO-A/LO and CMV, arterial oxygen tensions were 70 to 100 mm Hg. Mean lung volumes were 7.8 and 4.3 ml/kg, respectively. Total respiratory system pressure-volume curves (P-V curves) showed no change from baseline in the HFO-A/HI group after 7 h of ventilation. The low lung volume groups (HFO-A/LO and CMV) showed a diminution in hysteresis of their P-V curves, lower total respiratory system compliance, more hyaline membranes and severe airway epithelial damage. (All changes significant with p less than 0.05). We conclude that maintenance of alveolar volume is a key mechanism in the prevention of lung injury during mechanical ventilation of the atelectasis-prone lung. For optimal outcome using high frequency oscillatory ventilation, alveoli must be actively reexpanded and then kept expanded using appropriate mean airway pressures.

Airway Resistance↗
PubMed2002

Effects of respiratory rate, plateau pressure, and positive end-expiratory pressure on PaO2 oscillations after saline lavage.

One of the proposed mechanisms of ventilator-associated lung injury is cyclic recruitment of atelectasis. Collapse of dependent lung regions with every breath should lead to large oscillations in PaO2 as shunt varies throughout the respiratory cycle. We placed a fluorescence-quenching PO2 probe in the brachiocephalic artery of six anesthetized rabbits after saline lavage. Using pressure-controlled ventilation with oxygen, ventilator settings were varied in random order over three levels of positive end-expiratory pressure (PEEP), respiratory rate (RR), and plateau pressure minus PEEP (Delta). Dependence of the amplitude of PaO2 oscillations on PEEP, RR, and Delta was modeled by multiple linear regression. Before lavage, arterial PO2 oscillations varied from 3 to 22 mm Hg. After lavage, arterial PO2 oscillations varied from 5 to 439 mm Hg. Response surfaces showed markedly nonlinear dependence of amplitude on PEEP, RR, and Delta. The large PaO2 oscillations observed provide evidence for cyclic recruitment in this model of lung injury. The important effect of RR on the magnitude of PaO2 oscillations suggests that the static behavior of atelectasis cannot be accurately extrapolated to predict dynamic behavior at realistic breathing frequencies.

Animals↗
PubMed1996

Postoperative care following single-stage laryngotracheoplasty.

Single-stage laryngotracheoplasty (SSLTP) provides a method of correcting mild-to-moderate laryngotracheal stenosis while avoiding the risks of prolonged laryngeal stenting. Pediatric patients are orally intubated for 5 to 7 days postoperatively to ensure an adequate airway while edema resolves and healing begins. During this period, continuous neuromuscular blockade has been advocated in infants and young children to avoid endotracheal tube trauma to the fresh graft and potentially life-threatening accidental decannulation. Pulmonary atelectasis is the most common morbidity associated with prolonged neuromuscular blockade. Neuromuscular weakness also may follow prolonged paralysis and prolong hospitalization. This paper compares the postoperative course of 17 patients who underwent 18 SSLTP procedures by the senior author. The first 8 patients received continuous neuromuscular blockade in the early postoperative period. To reduce perceived morbidity, the last 9 patients were managed with a protocol that incorporated daily 4- to 8-hour "interruptions" of paralysis. Seven patients tolerated this protocol modification. As a group, these patients had less postoperative pulmonary atelectasis prior to extubation (p < .05) and were extubated sooner than patients receiving continuous neuromuscular blockade (p<.05) without compromising the surgical success of the procedure. Intermittent paralysis permitted for more accurate assessment of pain control and protected against accidental drug accumulation. Although self-extubation did not occur, diligent nursing care with adequate sedation and analgesia is necessary to avoid the risk of accidental extubation.

Child↗
PubMed1982

The role of the chest radiograph in the management of childhood asthma.

Emergency Room records were analyzed retrospectively for 1548 asthma patient visits over a 24-month period. Chest x-rays were obtained during 391 visits. Five per cent had focal atelectasis, ten per cent had a pulmonary infiltrate. There was no difference between the x-ray results of those children successfully treated as outpatients and those requiring hospitalization. Physicians frequently ordered x-rays for asthmatic children under 5 years of age, for those with temperature greater than 38.3 C, symptoms longer than 2 days, respiratory rate greater than 40, a more severe attack with asthma score greater than 3, or pulmonary rales. Significantly abnormal chest radiographs (focal atelectasis or pulmonary infiltrate) were found only in patients under 5 years old or in older patients with pulmonary rales. The other patient characteristics which appeared to indicate a more severe asthma attack did not correlate with abnormal radiograph reports. The routine chest x-ray does not appear to provide useful information for the design of treatment plans for children with asthma.

Age Factors↗
PubMed1990

Second place--Resident Clinical Science Award 1990. A porcine model of chronic endobronchial obstruction.

To elucidate the effects of both prolonged lobar atelectasis and subsequent re-expansion in a non-thoracotomized animal, we have developed a chronic, reversible porcine model of endobronchial obstruction. Eight adolescent pigs underwent the bronchoscopic placement of a left lower lobe bronchial plug. The obstruction was left in place for 24 hours. Four pigs then had the balloon bronchoscopically removed, while four controls underwent sham removal of the balloon. All animals showed significant atelectasis of the obstructed lobe compared to non-obstructed lobes at 24 hours. Pulmonary blood flow decreased significantly 24 hours after obstruction compared to pre-obstruction values in the collapsed lobe in all animals. Re-expansion was followed by arterial hypoxemia, which was accompanied by an increase in relative blood flow to the partially re-expanded lobe in the experimental group. No significant changes in lung water content occurred in the study group compared to controls.

Animals↗
PubMed2006

Feasibility of preoperative inspiratory muscle training in patients undergoing coronary artery bypass surgery with a high risk of postoperative pulmonary complications: a randomized controlled pilot study.

OBJECTIVE: To determine in a pilot study the feasibility and effects of preoperative inspiratory muscle training in patients at high risk of postoperative pulmonary complications who were scheduled for coronary artery bypass graft surgery. DESIGN: Single-blind, randomized controlled pilot study. SETTING: University Medical Centre Utrecht, the Netherlands. SUBJECTS: Twenty-six patients at high risk of postoperative pulmonary complications were selected. INTERVENTION: The intervention group (N = 14) received 2-4 weeks of preoperative inspiratory muscle training on top of the usual care received by the patients in the control group. MAIN MEASURES: Primary outcome variables of feasibility were the occurrence of adverse events, and patient satisfaction and motivation. Secondary outcome variables were postoperative pulmonary complications and length of hospital stay. RESULTS: The feasibility of inspiratory muscle training was good and no adverse events were observed. Treatment satisfaction and motivation, scored on 10-point scales, were 7.9 (+/- 0.7) and 8.2 (+/- 1.0), respectively. Postoperative atelectasis occurred in significantly fewer patients in the intervention group than in the control group (kappa(2)(DF1) = 3.85; P = 0.05): Length of hospital stay was 7.93 (+/- 1.94) days in the intervention group and 9.92 (+/- 5.78) days in the control group (P = 0.24). CONCLUSION: Inspiratory muscle training for 2-4 weeks before coronary artery bypass graft surgery was well tolerated by patients at risk of postoperative pulmonary complications and prevented the occurrence of atelectasis in these patients. A larger randomized clinical trial is warranted.

Aged↗
PubMed1975

A new model for neonatal pulmonary hemorrhage research.

Hemorrhagic atelectasis was successfully produced in newborn rabbits by pharmacologically narrowing airways leading to alveoli ventilated with oxygen-enriched gas. Between 48% and 62% of alveoli filled with blood cells. Areas of lung with a tendency to collapse were measured by pressure volume studies. Animals given supplemental oxygen retained 56% of total lung volume compared with 79% in the pilocarpine group, which suggested increased effectiveness of anti-atelectasis factors in the latter. Less total lung gas was present in the pilocarpine group (4.0 plus or minus 0.4 cc/g) compared with oxygen controls (5.1 plus or minus 0.81 cc/g), which indicated more noninflatable lung. Neither surfactant deficiency nor heart failure needed to be present for pulmonary hemorrhage to occur.

Animals↗
PubMed2006

The implications of arterial Po2 oscillations for conventional arterial blood gas analysis.

In a surfactant-depletion model of lung injury, tidal recruitment of atelectasis and changes in shunt fraction lead to large Pao2 oscillations. We investigated the effect of these oscillations on conventional arterial blood gas (ABG) results using different sampling techniques in ventilated rabbits. In each rabbit, 5 different ventilator settings were studied, 2 before saline lavage injury and 3 after lavage injury. Ventilator settings were altered according to 5 different goals for the amplitude and mean value of brachiocephalic Pao2 oscillations, as guided by a fast responding intraarterial probe. ABG collection was timed to obtain the sample at the peak or trough of the Pao2 oscillations, or over several respiratory cycles. Before lung injury, oscillations were small and sample timing did not influence Pao2. After saline lavage, when Po2 fluctuations measured by the indwelling arterial Po2 probe confirmed tidal recruitment, Pao2 by ABG was significantly higher at peak (295 +/- 130 mm Hg) compared with trough (74 +/- 15 mm Hg) or mean (125 +/- 75 mm Hg). In early, mild lung injury after saline lavage, Pao2 can vary markedly during the respiratory cycle. When atelectasis is recruited with each breath, interpretation of changes in shunt fraction, based on conventional ABG analysis, should account for potentially large respiratory variations in arterial Po2.

Animals↗
PubMed1993

Spontaneous pneumothorax following partial resolution of total bronchial obstruction.

Spontaneous pneumothorax following chest irradiation is thought to occur in patients with radiation fibrosis several months or more after the completion of therapy. In the four patients presented herein, spontaneous pneumothorax was seen during or immediately after therapeutic radiation of lung cancer. All patients had bronchoscopic findings of bronchial obstruction by the tumor before treatment and radiographic improvement of atelectasis was observed during therapy. The interval between the improvement of atelectasis and the development of pneumothorax varied by less than three weeks. These common findings suggest that rupture of alveoli or emphysematous bullae and subsequent pneumothorax might be due to overinflation of the affected lung caused by partial bronchial obstruction. We should be aware of the occurrence of spontaneous pneumothorax following partial resolution of total bronchial obstruction.

Aged↗
PubMed1994

Multiple pulmonary chondromata. A rare cause of neonatal respiratory distress.

A neonate with respiratory distress due to a right pneumothorax is presented. After drainage of the pneumothorax, atelectasis of the entire right lung developed. Because the atelectasis persisted, bronchoscopy was performed. On bronchoscopy the carina and right main-stem bronchus could not be visualized. Thoracotomy showed that the right main-stem bronchus was obstructed by a space-occupying lesion that was originating from the right upper lobe. Therefore, a sleeve resection of the right upper lobe was performed, and the right main-stem bronchus was reconstructed. Microscopic examination of the resected right upper lobe showed multiple chondromata. The lesions were located both in the lung parenchyma immediately beneath the pleura and in the bronchial wall. Pulmonary chondromata are rarely diagnosed in children. To our knowledge, this is the youngest patient ever presented with pulmonary chondromata.

Chondroma↗
PubMed1994

Fiberoptic bronchoscopy in the evaluation of carcinoma metastatic to the lung.

To determine the clinical presentation of patients with malignancies metastatic to the lung, the diagnostic utility of fiberoptic bronchoscopy (FB), and the primary site of malignancies metastasizing endobronchially, we retrospectively reviewed 1,853 FB records (1987 to 1991) and selected 111 cases for review. Cases were divided on the basis of FB findings into abnormal (44 patients) and normal (67 patients). Pulmonary symptoms (cough, hemoptysis, and chest pain) prompted referral significantly more often in the abnormal FB group (34/44) than in the normal FB group (24/67). The finding of atelectasis on chest radiograph occurred more frequently in patients with endobronchial abnormalities. The spectrum of extrapulmonary malignancies that metastasize endobronchially has changed during the AIDS epidemic. Our study shows the most frequent causes of endobronchial mass lesions were Kaposi's sarcoma and the lymphoma group (Hodgkin's disease, nonHodgkin's lymphoma, chronic lymphocytic leukemia) and the most common malignancies causing submucosal metastases were breast and the lymphoma group. In summary, the highest yield from FB can be expected in patients experiencing symptoms of cough or hemoptysis and/or having radiographic evidence of atelectasis. We propose a new mnemonic "KLAS" (Kaposi's sarcoma, Lymphoma, Adenocarcinoma, Sarcoma) to describe the malignancies most likely to metastasize endobronchially in the 1990s.

Biopsy↗
PubMed1994

Chest tubes, lung entrapment, and failure to wean from the ventilator. Report of three patients with quadriplegia.

The cases of three patients with traumatic quadriplegia who had been treated with chest tubes are described. Each had been injured at a neurologic level that typically allows weaning from the ventilator, yet none was able to clear refractory atelectasis or become ventilator free. Each underwent surgery during which lung adhesions, entrapment, or deformation at the former chest tube site were identified and corrected. Subsequently, each patient cleared his atelectasis and weaned from the ventilator. These cases suggest the importance of ruling out lung deformity in individuals with ventilator-dependent quadriplegia who have had chest tubes and unexpectedly fail to wean.

Adult↗
PubMed1994

Use of fiberoptic bronchoscopy in the diagnosis of bronchogenic carcinoma. A study in patients with idiopathic pleural effusions.

We reviewed our experience with 115 patients with pleural effusion in whom bronchogenic carcinoma was suspected who underwent fiberoptic bronchoscopy (FOB) to identify those for whom the procedure was useful. In 6 of 12 patients with hemoptysis, 8 of 12 with a mass or infiltrate, and 8 of 18 with atelectasis with negative fluid cytology and 3 of 7 with cytology positive, FOB was useful in diagnosis. Sixty-six patients had an isolated cytology-negative effusion. Seven of 18 with massive effusion had FOB detecting cancer. Fiberoptic bronchoscopy usually was nondiagnostic in lesser-sized effusions (47 of 48). Using outcome for those with nondiagnostic FOB, we established operating characteristics for the procedure. We conclude that FOB is useful in diagnosing bronchogenic carcinoma in such patients when there is hemoptysis, accompanying lung mass or infiltrate, atelectasis, the effusion is massive, or in cytology-positive effusions without obvious primary tumor. Due to the low prevalence of bronchogenic carcinoma in patients with effusions of lesser size, we suggest that in this group FOB not be routinely performed.

Bronchoscopes↗
PubMed1998

Pulmonary infiltrates in the surgical ICU: prospective assessment of predictors of etiology and mortality.

A prospective cohort study of 129 consecutive patients developing pulmonary infiltrates in the surgical ICU was conducted to determine the predictors and outcome of pulmonary infiltrates. Most common etiologies of pulmonary infiltrates were pneumonia (30%), pulmonary edema (29%), acute lung injury (15%), and atelectasis (13%). Enteral nutrition was associated with a significantly lower incidence of acute lung injury as compared with pneumonia (22% vs 58%, p = 0.012). Patients with liver disease were significantly more likely to have pulmonary infiltrates due to acute lung injury as compared with other etiologies (p = 0.02). Clinical pulmonary infection score (Pugin score) > 6 virtually excluded acute lung injury, pulmonary edema, or atelectasis as etiologies of pulmonary infiltrates. Nosocomial Haemophilus/pneumococcal pneumonia occurred significantly earlier in the ICU as compared with Gram-negative (p = 0.05) or methicillin-resistant Staphylococcus aureus pneumonia (p = 0.01). Pneumonia in trauma patients was significantly more likely to be due to Haemophilus/pneumococcus as compared with all other ICU patients (54% vs 0%, p = 0.0004). These data have implications for treatment of patients with nosocomial pneumonia in the ICU.

APACHE↗
PubMed2000

Patient preferences regarding possible outcomes of lung resection: what outcomes should preoperative evaluations target?

CONTEXT: Lung resection can lead to significant postoperative complications: Although many reports describe the likelihood of postoperative problems, such as atelectasis, pneumonia, and prolonged ventilator dependence, it is unclear whether patients perceive these outcomes as sufficiently severe to influence their decisions about surgery. OBJECTIVE: To assess patients' preferences regarding possible outcomes of lung resection, including traditional complications reported in the lung surgery literature and outcomes that describe functional limitation. DESIGN: Utility analysis. SETTING: A community hospital internal medicine clinic, a private internal medicine practice, and a private pulmonary practice. PARTICIPANTS: Sixty-four patients, aged 50 to 75 years, who were awaiting appointments at the designated clinic sites. MAIN OUTCOME MEASURE: Patients' strength of preference regarding potential outcomes of lung resection as derived from health utility scores. RESULTS: Common postoperative complications were assigned high utility scores by patients. On a scale for which 1.0 represents perfect health and 0 represents death, postoperative atelectasis, pneumonia, and 3 days of mechanical ventilation were all rated >0.75. Scores describing limited physical function were strikingly low. Specifically, activity limited to bed to chair movement and the need for complete assistance with activities of daily living were all assigned utility scores <0.2. Twenty-four-hour oxygen dependence was scored at 0.33. Presence or absence of pulmonary illness did not predict scores for any outcome. CONCLUSIONS: Whether patients suffer from chronic lung disease or not, they do not regard the postoperative outcomes reported in the lung surgery literature as sufficiently morbid to forego important surgery. However, physical debility is perceived as extremely undesirable, and anticipation of its occurrence could deter surgery. Therefore, identification of preoperative predictors of postoperative physical debility would be invaluable for counseling patients who face difficult decisions about lung resection.

Aged↗
PubMed2003

Pulmonary resection in infants for congenital pulmonary malformation.

STUDY OBJECTIVES: To review our experience with indications, timing, and results of pulmonary resection in infants. DESIGN: Retrospective cohort study. SETTING: Thoracic Surgery Department, Chest Diseases Hospital, Kuwait. PATIENTS AND INTERVENTION: Forty-seven infants with congenital lung diseases were treated with pulmonary resection from January 1993 to December 2000. RESULTS: The mean age at the time of diagnosis was 90 days (range, 7 days to 11 months). Thirty-four patients were male (72%). Congenital lobar emphysema, congenital cystic adenomatoid malformation, pulmonary sequestration, and atelectasis were seen in 26, 10, 6, and 5 patients, respectively. The indications for surgery were respiratory distress in 32 patients (68%), respiratory tract infections in 12 patients (26%), and the presence of asymptomatic chest radiographic findings in 3 patients (6%). A lobectomy was performed in 42 patients (89%), bilobectomy in 2 patients (4%), left pneumonectomy in 1 patient (2%), and excision of a mass in 2 patients with extralobar sequestration (4%). An emergency lobectomy was performed in seven patients (15%). Only one postoperative death occurred following a left pneumonectomy for extensive congenital adenomatoid malformation due to pulmonary hypertension. Four patients (9%) had postoperative complications: atelectasis (n = 2), prolonged air leak (n = 1), and pneumothorax (n = 1). Mean follow-up was 4 years (range, 1 to 5 years) for all patients. None of the patients had any physical limitations. CONCLUSION: Pulmonary resection is indicated for the majority of patients with congenital lung malformations. In case of severe respiratory distress, an emergency lobectomy can be performed safely.

Bronchopulmonary Sequestration↗