Permeability pulmonary edema following lung resection

Bedside sonography assessment of extravascular lung water increase after major pulmonary resection in non-small cell lung cancer patients

Background

Extra vascular lung water (EVLW) following pulmonary resection increases due to fluid infusion and rises in capillary surface and permeability of the alveolar capillary membranes. EVLW increase clinically correlates to pulmonary oedema and it may generate impairments of gas exchanges and acute lung injury. An early and reliable assessment of postoperative EVLW, especially following major pulmonary resection, is useful in terms of reducing the risk of postoperative complications. The currently used methods, though satisfying these criteria, tend to be invasive and cumbersome and these factors might limit its use. The presence and burden of EVLW has been reported to correlate with sonographic B-line artefacts (BLA) assessed by lung ultrasound (LUS). This observational study investigated if bedside LUS could detect EVLW increases after major pulmonary resection. Due to the clinical association between EVLW increase and impairment of gas exchange, secondary aims of the study included investigating for associations between any observed EVLW increases and both respiratory ratio (PaO₂/FiO₂) and fluid retention, measured by brain natriuretic peptide (BNP).

Methods

Overall, 74 major pulmonary resection patients underwent bedside LUS before surgery and at postoperative days 1 and 4, in the inviolate hemithorax which were divided into four quadrants. BLA were counted with a four-level method. The respiratory ratio PaO₂/FiO₂ and fluid retention were both assessed.

Results

BLA resulted being increased at postoperative day 1 (OR 9.25; 95% CI, 5.28-16.20; P<0.0001 vs. baseline), and decreased at day 4 (OR 0.50; 95% CI, 0.31-0.80; P=0.004 vs. day 1). Moreover, the BLA increase was associated with both increased BNP (OR 1.005; 95% CI, 1.003-1.008; P<0.0001) and body weight (OR 1.040; 95% CI, 1.008-1.073; P=0.015). Significant inverse correlations were observed between the BLA values and the PaO₂/FiO₂ respiratory ratios.

Conclusions

Our results suggest that LUS, due to its non-invasiveness, affordability and capacity to detect increases in EVLW, might be useful in better managing postoperative patients.

Special article: the endothelial glycocalyx: emerging concepts in pulmonary edema and acute lung injury

The endothelial glycocalyx is a dynamic layer of macromolecules at the luminal surface of vascular endothelium that is involved in fluid homeostasis and regulation. Its role in vascular permeability and edema formation is emerging but is still not well understood. In this special article, we highlight key concepts of endothelial dysfunction with regards to the glycocalyx and provide new insights into the glycocalyx as a mediator of processes central to the development of pulmonary edema and lung injury.

Acute respiratory distress syndrome after pulmonary resection

Postoperative acute respiratory distress syndrome (ARDS) is a recognized complication of pulmonary resection. It is characterized by the acute onset of hypoxemia with radiographic infiltrates consistent with pulmonary edema, without elevations in the pulmonary capillary wedge pressure. Many studies suggest that around 2-5 % of patients develop some degree of lung injury, and the mortality from ARDS following pulmonary resection remains high. ARDS following thoracotomy and lung resection has a miserable prognosis, with overall hospital mortality rates over 25 %. The present review evaluates the evidence available in the literature tracking perioperative mortality and morbidity as well as the pathogenesis and management of ARDS in patients undergoing pulmonary resection.

Role of particle beam therapy in a trimodality approach to locally advanced non-small cell lung cancer

Lung cancer accounts for nearly one-fifth of all cancer deaths worldwide and is the most common cause of cancer-related death in the United States. Outcomes for locally advanced non-small cell lung cancer remain extremely poor with regards to both local control and overall survival. Modest gains in local control were obtained with the incorporation of multimodality treatment, including preoperative chemotherapy followed by surgical resection; combination chemoradiotherapy also improved survival, secondary to improved local control. While the natural progression to trimodality therapy resulted in superior local control, it did not translate to improved overall survival, secondary to increased toxicity. The additional morbidity is likely from radiation toxicity, the minimization of which will be crucial to the future success of trimodality therapy. One strategy to decrease toxicity is to utilize charged particles, such as protons, which deposit a high dose at the Bragg peak with a minimal dose beyond the peak, thereby reducing the dose to distal normal tissues. Trimodality therapy incorporating preoperative proton radiation therapy and chemotherapy, followed by surgery, is currently being evaluated as a potential strategy to achieve improved local control and overall survival in locally advanced non-small cell lung cancer.

Determining the aetiology of pulmonary oedema by the oedema fluid-to-plasma protein ratio

We hypothesised that the oedema fluid-to-plasma protein (EF/PL) ratio, a noninvasive measure of alveolar capillary membrane permeability, can accurately determine the aetiology of acute pulmonary oedema. 390 mechanically ventilated patients with acute pulmonary oedema were enrolled. A clinical diagnosis of acute lung injury (ALI), cardiogenic pulmonary oedema or a mixed aetiology was based on expert medical record review at the end of hospitalisation. The EF/PL ratio was measured from pulmonary oedema fluid and plasma samples collected at intubation. 209 patients had a clinical diagnosis of ALI, 147 had a diagnosis of cardiogenic pulmonary oedema and 34 had a mixed aetiology. The EF/PL ratio had an area under the receiver-operating curve of 0.84 for differentiating ALI from cardiogenic pulmonary oedema. Using a predefined cut-off of 0.65, the EF/PL ratio had a sensitivity of 81% and a specificity of 81% for the diagnosis of ALI. An EF/PL ratio >/=0.65 was also associated with significantly higher mortality and fewer ventilator-free days. Noninvasive measurement of the EF/PL ratio is a safe and reliable bedside method for rapidly determining the aetiology of acute pulmonary oedema that can be used at the bedside in both developed and developing countries.

Upright position mechanical ventilation: an alternative strategy for ALI/ARDS patients?

Use of body positioning to improve oxygenation in mechanically ventilated patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) has been well documented. However, neither prone position ventilation nor side lying ventilation has been reported to improve the survival. Whether there is a body position superior to routine supine position or other positions as therapeutic adjunct for ventilated patients with ALI and ARDS? We propose the hypothesis that upright position ventilation may be helpful to improve oxygenation and benefit patients with ALI/ARDS. According to the existing physiologic and pathophysiologic data of upright position investigation, we suppose that improvement of V/Q matching, increased functional residual capacity, alveolar recruitment, accelerated diaphragm recovery, early gastric emptying and enteric feeding may be a potential protect mechanism of upright position ventilation. Whether this can be translated into improvement in patient outcome should be further tested in clinical trial.

Respiratory failure following pulmonary resection

Improvements in the perioperative management of the patient undergoing pulmonary resections have reduced postoperative complication rates steadily in the last several decades. However, postresection respiratory failure, particularly lung injury with no discernible cause, remains a major cause of morbidity and mortality. Because the incidence of this entity is relatively low, the terminology, pathogenesis, and optimal management are poorly delineated in the literature. The purpose of this review is to describe the criteria used to define postresection lung injury, discuss the possible etiologic factors, and outline currently available treatment strategies.

Incidence and Risk Factors for Lung Injury After Lung Cancer Resection

BACKGROUND

Lung injury, defined as acute hypoxemia accompanied by radiographic pulmonary infiltrates without a clearly identifiable cause, is a major cause of morbidity and mortality after major anatomic pulmonary resection. Our objective was to identify the incidence and risk factors for the development of postoperative lung injury.

METHODS

A retrospective case-control study of consecutive patients undergoing resection for lung cancer at a single institution was performed. The severity of lung injury was defined using the American European Consensus Conference on ARDS (acute respiratory distress syndrome) criteria and the National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0 (http://ctep.cancer.gov/reporting/ctc.html). Patients with lung injury were compared with matched control patients, based on age, sex, and extent of resection, for examination of a priori defined risk factors.

RESULTS

From January 2001 to June 2004, 1,428 patients underwent attempted curative lung cancer resection. Postoperative lung injury occurred in 76 (5.3%) cases, 44 (3.1%) of which met criteria for acute lung injury or acute respiratory distress syndrome. After matching, there were no differences between cases and control patients with respect to use of induction therapy, perioperative transfusions, or tumor laterality. After univariate and multivariate analysis, increasing perioperative fluid administration and decreasing postoperative predicted lung function were significant risk factors for the development of lung injury. The overall mortality for patients with lung injury was 25%, compared with 2.6% for the control group.

CONCLUSIONS

Lung injury after lung resection has a high mortality. Lower predicted postoperative lung function, especially diffusion capacity, in combination with greater perioperative fluid administration were significant predictors of postoperative lung injury.

Radiographic and CT Findings of Thoracic Complications after Pneumonectomy

Pneumonectomy is the treatment of choice for bronchogenic carcinoma and intractable end-stage lung diseases such as tuberculosis and bronchiectasis, but it is often followed by postoperative complications, which account for significant morbidity and mortality. Knowledge of the radiologic features of such complications is of critical importance for their early detection and prompt management. Complications of pneumonectomy are classified as early or late, depending on when they occur in relation to the hospitalization period. Early complications of pneumonectomy include pulmonary edema, bronchopleural fistula, pneumonia of the contralateral lung, empyema, and adult respiratory distress syndrome, which may occur separately or in combination. Late postpneumonectomy complications include recurrent disease, infection, effects of radiation therapy or chemotherapy, and surgical complications such as late-onset bronchopleural fistula, postpneumonectomy syndrome, and esophagopleural fistula. Sequential examinations with chest radiography after pneumonectomy are an invaluable method of screening for these complications, especially in the early postoperative period. When the radiographic findings are inconclusive, computed tomography is helpful for establishing a diagnosis and obtaining detailed information about the disease process.

Complications of Pulmonary Resection: Postpneumonectomy Pulmonary Edema and Postpneumonectomy Syndrome

Bassed on the authors' review of the unusual variants of PPS and the body of published experience, a revision of the current classification scheme for PPS into a more comprehensive form is justified as follows: (1) by the nature of obstruction; and (2) by the time of onset. This classification encompasses early and late symptom onset, as well as considering both airway and vascular compression. This scheme argues in favor of an expanded cardiac work-up in addition to the measures outlined previously for airway assessment. Althought PPS remains a rare clinical entity, the refinement in the understanding of this condition and the evolution of treatment options have vastly improved patient outcomes. A careful evaluation of the patient must be done before embarking on treatment owing to the numerous etiologies for progressive dyspnea in the pneumonectomy patient.

Recombinant Human Serum Albumin Dimer has High Blood Circulation Activity and Low Vascular Permeability in Comparison with Native Human Serum Albumin

PURPOSE

Human serum albumin (HSA) is used clinically as an important plasma expander. Albumin infusion is not recommended for critically ill patients with hypovolemia, burns, or hypoalbuminemia because of the increased leakage of albumin into the extravascular spaces, thereby worsening edema. In the present study, we attempted to overcome this problem by producing a recombinant HSA (rHSA) dimer with decreased vascular permeability and an increased half-life.

METHODS

Two molecules of rHSA were genetically fused to produce a recombinant albumin dimer molecule. The pharmacokinetics and biodistribution of the recombinant proteins were evaluated in normal rats and carrageenin-induced paw edema mouse model.

RESULTS

The conformational properties of this rHSA dimer were similar to those for the native HSA (the HSA monomer), as evidenced by the Western blot and spectroscopic studies. The biological half-life and area under the plasma concentration-time curve of the rHSA dimer were approximately 1.5 times greater than those of the monomer. Dimerization has also caused a significant decrease in the total body clearance and distribution volume at the steady state of the native HSA. rHSA dimer accumulated to a lesser extent in the liver, skin, muscle, and fat, as compared with the native HSA. Up to 96 h, the vascular permeability of the rHSA dimer was less than that of the native HSA in paw edema mouse models. A prolonged plasma half-life of the rHSA dimer was also observed in the edema model rats.

CONCLUSIONS

rHSA dimer has a high retention rate in circulating blood and a lower vascular permeability than that of the native HSA.

Acute exacerbation of interstitial pneumonia following surgical lung biopsy

STUDY OBJECTIVES

Surgical lung biopsy (SLB) plays an important role in the diagnosis of interstitial pneumonia, however, the occurrence of acute respiratory failure following SLB remains largely unreported. We evaluated the incidence, clinical features, therapy and prognosis of acute exacerbation of interstitial pneumonia following SLB.

DESIGN

Retrospective study of consecutive patients who underwent SLB to establish a diagnosis of diffuse lung disease between May 1989 and April 2000. Patients with an acute exacerbation following lung biopsy were studied, and the HRCT images of the chest before and after surgery were reviewed.

MEASUREMENTS AND RESULTS

Among the 236 consecutive patients with interstitial pneumonia who underwent a surgical lung biopsy, five (2.1%) (IPF, 3; NSIP, 1; COP, 1) developed acute exacerbation of the diffuse lung disease in the course of 1-18 days after SLB. The extent of parenchymal involvement on HRCT before surgery was not significantly different between operated and contralateral nonoperated lung. Significantly increased regions of parenchymal involvement on HRCT were seen postoperatively compared with the preoperative CT in both the operated (20.7+/-12.5% versus 38.2+/-10.8%, P = 0.0431) and nonoperated lung (22.7+/-13.8% versus 70.5+/-24.4%, P = 0.0431), but the extent of the parenchymal involvement was significantly greater on the nonoperated side (P = 0.0251). Two of the 3 IPF patients died from the acute exacerbation.

CONCLUSIONS

It is important to be aware of the possibility of acute exacerbation of interstitial pneumonia following SLB even after an apparently uneventful immediate postoperative course. The asymmetric image findings suggest that intraoperative respiratory management is a possible etiologic factor.

Accuracy and limits of transpulmonary dilution methods in estimating extravascular lung water after pneumonectomy

STUDY OBJECTIVES

The measurement of extravascular lung water index by double indicator (EVLWIdi) or the measurement of extravascular lung water index by transpulmonary thermodilution (EVLWItt) could be useful after pneumonectomy. Since pulmonary blood flow and volume are altered after pneumonectomy, the validity of these methods is uncertain. This study has compared measurements of EVLWIdi and EVLWItt with measurement of extravascular lung water index by gravimetry (EVLWIg) in a porcine model of pulmonary edema induced after right pneumonectomy.

DESIGN

Randomized laboratory study.

SETTING

Animal research laboratory.

SUBJECTS

Twenty-seven female pigs; mean weight, 35 +/- 5 kg (+/- SD).

INTERVENTIONS

The pigs were anesthetized, placed on mechanical ventilation, and allocated to a two-lung group (n = 10) or a right pneumonectomy group (n = 17). EVLWIdi and EVLWItt were measured at baseline, 60 min after pneumonectomy, and 60 min after IV injection of oleic acid (OA).

MEASUREMENTS AND RESULTS

There was a good correlation between EVLWIg and EVLWIdi values (r = 0.96, p < 0.0001 in the two-lung group; and r = 0.81, p = 0.02 in the pneumonectomy group). EVLWIdi underestimated EVLWIg in the two-lung group (- 3 mL/kg; 95% confidence interval [CI], - 7 to + 2 mL/kg) and in the pneumonectomy group (- 0.9 mL/kg; 95% CI, - 3.3 to + 1.5 mL/kg). After pneumonectomy, EVLWItt decreased in mean by 27% and increased in mean by 70% after OA acid. There was a good correlation between EVLWIg and EVLWItt values (r = 0.96, p < 0.0001 in the two-lung group; and r = 0.90, p < 0.0001 after pneumonectomy). EVLWItt slightly overestimated gravimetric value in the two-lung group (+ 1.5 mL/kg; 95% CI, - 1.5 to + 4.2 mL/kg) and largely overestimated gravimetric value after pneumonectomy (+ 5 mL/kg; 95% CI, + 3.4 to + 6.8 mL/kg).

CONCLUSION

Double-indicator and transpulmonary thermodilution methods could be useful in monitoring extravascular lung water index (EVLWI) after pneumonectomy, but transpulmonary thermodilution largely overestimates EVLWI.

Edema pulmonar pós-pneumonectomia

A pneumonectomia, embora seja tecnicamente simples, está associada a alta incidência de complicações (cerca de 60%). As complicações respiratórias correspondem a aproximadamente 15% deste total. A mortalidade global dessa cirurgia é de 8,6%, mas em presença de complicações respiratórias, a taxa de mortalidade chega a 30%. O edema pulmonar pós-pneumonectomia é uma complicação rara (3% a 5%), mas muito grave, sendo fatal na maioria dos casos. Foi descrito pela primeira vez há pouco mais de vinte anos mas, apesar da gravidade alarmante, pouco sabemos acerca de sua fisiopatologia, embora muitas hipóteses tenham sido levantadas. Uma vez instalado, nenhuma medida é comprovadamente eficaz no seu tratamento. Vários fatores de risco estão associados ao aparecimento do edema pulmonar pós-pneumonectomia, dentre os quais a sobrecarga hídrica, que foi o primeiro fator evitado. Entretanto, muitos trabalhos mostram não haver relação direta entre o volume recebido e o desenvolvimento do edema. A prevenção é a melhor forma de evitá-lo e deve ser realizada de maneira multifatorial, envolvendo toda a equipe médica, desde o momento da anestesia até os cuidados cirúrgicos e na terapia intensiva. No entanto, tão importante quanto a prevenção, é a suspeita clínica precoce, identificando os pacientes em risco para essa grave complicação.

Anesthetic strategies for patients undergoing extrapleural pneumonectomy

Anesthetic management of patients with extrapleural pneumonectomy may contribute to risk reduction, and it differs from management of patients with standard pneumonectomy in several respects. Hemodynamic and intravascular fluid management is complicated by the significantly greater blood loss and impairments of venous return imposed by weighty tumors and the blunt dissection process. There are greater risks of catastrophic (central) bleeding, dysrhythmias, cardiac herniation, and electrocardiographic changes. Restrictive forces increase the likelihood of dependent lung atelectasis during single-lung ventilation. Preoperative assessment of cardiopulmonary reserve remains an imprecise process. Awareness of these risks and limitations enables the anesthesiologist to understand, anticipate, and potentially preempt many intraoperative problems.

Risk Factors for Acute Lung Injury After Thoracic Surgery for Lung Cancer

Acute lung injury (ALI) may complicate thoracic surgery and is a major contributor to postoperative mortality. We analyzed risk factors for ALI in a cohort of 879 consecutive patients who underwent pulmonary resections for non-small cell lung carcinoma. Clinical, anesthetic, surgical, radiological, biochemical, and histopathologic data were prospectively collected. The total incidence of ALI was 4.2% (n = 37). In 10 cases, intercurrent complications (bronchopneumonia, n = 5; bronchopulmonary fistula, n = 2; gastric aspiration, n = 2; thromboembolism, n = 1) triggered the onset of ALI 3 to 12 days after surgery, and this was associated with a 60% mortality rate (secondary ALI). In the remaining 27 patients, no clinical adverse event preceded the development of ALI-0 to 3 days after surgery-that was associated with a 26% mortality rate (primary ALI). Four independent risk factors for primary ALI were identified: high intraoperative ventilatory pressure index (odds ratio, 3.5; 95% confidence interval, 1.7-8.4), excessive fluid infusion (odds ratio, 2.9; 95% confidence interval, 1.9-7.4), pneumonectomy (odds ratio, 2.8; 95% confidence interval, 1.4-6.3), and preoperative alcohol abuse (odds ratio, 1.9; 95% confidence interval, 1.1-4.6). In conclusion, we describe two clinical forms of post-thoracotomy ALI: 1). delayed-onset ALI triggered by intercurrent complications and 2). an early form of ALI amenable to risk-reducing strategies, including preoperative alcohol abstinence, lung-protective ventilatory modes, and limited fluid intake.

IMPLICATIONS

In an observational study including all patients undergoing lung surgery, we describe two clinical forms of acute lung injury (ALI): a delayed-onset form triggered by intercurrent complications and an early form associated with preoperative alcohol consumption, pneumonectomy, high intraoperative pressure index, and excessive fluid intake over the first 24 h.

Strategic leukocyte depletion reduces pulmonary microvascular pressure and improves pulmonary status post-cardiopulmonary bypass

Cardiopulmonary bypass (CPB) precipitates inflammation that causes marked pulmonary dysfunction. Leukocyte filtration has been proposed to reduce these deleterious effects. Other studies show an improvement with aprotinin. We proposed that a combination of these two therapies would synergistically improve pulmonary outcomes. Two hundred and twenty-five patients participated in a randomized prospective study comparing pulmonary microvascular function and pulmonary shunt fraction postcoronary artery bypass grafting (CABG). The study group underwent leukocyte depletion with aprotinin during the procedure. Pulmonary microvascular function was assessed by pulmonary microvascular pressure (PMVP), a measure of pulmonary capillary edema, and pulmonary function was evaluated by comparing pulmonary shunt fractions. Elevated PMVP and increased pulmonary shunting compromise pulmonary performance. The leukocyte-depleted group had significantly reduced PMVP and pulmonary shunt fraction for at least the first 24 hours postbypass. The combination of strategic leukocyte filtration and aprotinin therapy can effectively reduce postoperative decline in pulmonary function. Cardiopulmonary bypass precipitates a variety of inflammatory effects that can cause marked pulmonary dysfunction to the point of respiratory failure, necessitating prolonged mechanical ventilation. Leukocyte filtration has been investigated previously and appears to be beneficial in improving pulmonary outcome by preventing direct neutrophil-induced inflammatory injury. Recent studies of leukocyte reduction profiles suggest that leukoreduction via leukofiltration is short lived with filter saturation occurring 30-45 minutes after onset of filtration. This phenomenon may explain the limited utility observed with higher risk patients. These patients typically require longer pump runs, so leukocyte reduction capability is suboptimal at the time of pulmonary vascular reperfusion. To more effectively protect the lung from reperfusion injury, leukocyte filtration can be delayed so that reduction of activated neutrophils is maximal at the time of pulmonary vascular reperfusion. It is, thus, conceivable that a timely use of arterial line leukoreducing filters may improve, more substantially, pulmonary function postbypass. Two hundred and twenty-five isolated coronary revascularization patients participated in this prospective, randomized trial. The patients received moderately hypothermic CBP alone (control group: n = 110) or combined with leukocyte depletion, initiated 30 minutes before crossclamp release, with filters placed in the bypass circuit (study group: n = 115). All patients also received full Hammersmith aprotinin dosing during the operation. Pulmonary microvascular pressures were lower in the study group at three hours postbypass, and continued to fall until 24 hours postbypass. In contrast, the control group measured a rise in PMVP and a continued plateau throughout 24 hours postbypass (p < 0.028). The calculated pulmonary shunt fraction also was reduced significantly throughout the study interval, with the greatest reduction occurring approximately three to six hours post-CPB (p < 0.002). Shunt fractions eventually converged at 24 hours postbypass. Outcome measures included hospital charges and length of stay, which were also markedly reduced in the treatment group. Increasing PMVPs are a direct reflection of pulmonary capillary edema, which, in conjunction with increased pulmonary shunt ratio, lead to an overall worsening of pulmonary function. Intraoperative strategic leukocyte filtration combined with aprotinin treatment improves post-CPB lung performance by reducing significantly the reperfusion inflammatory response and its sequelae. These benefits are manifested by reductions in ventilator times, hospital stay and patient morbidity.

Gastroesophageal reflux and tracheal aspiration in the thoracotomy position: should ranitidine premedication be routine?

Aspiration of gastric contents may contribute to pulmonary complications after thoracotomy. The incidence of gastroesophageal reflux (GER) and tracheal acid aspiration in patients undergoing thoracotomy in the lateral position is unknown. Ranitidine premedication reduces gastric volume, increases gastric pH, and may reduce GER. We used continuous intraluminal esophageal and tracheal pH monitoring probes to investigate the effect of ranitidine on the incidence of GER and tracheal aspiration in 80 adult patients undergoing thoracotomy. The study was placebo-controlled, randomized, and double-blinded. Patients at high risk of GER were excluded from the study. The incidence of acid GER in the placebo and ranitidine groups was 28.2% and 2.5%, respectively (P = 0.006). Multiple episodes of GER occurred in some patients in the placebo group only. The total number of episodes of GER in the placebo and ranitidine groups was 16 and 1, respectively (P = 0.002). The incidence of tracheal acid aspiration in the placebo and ranitidine groups was 7.7% and 2.5%, respectively (not significant). Patients undergoing thoracotomy are therefore at high risk of acid GER, which may lead to tracheal acid aspiration in an appreciable proportion. Premedication with ranitidine significantly reduces, but does not eliminate, the incidence of this potentially life-threatening complication.

IMPLICATIONS

Gastroesophageal reflux (GER) and tracheal aspiration of acid may increase morbidity and mortality in patients undergoing thoracotomy. This randomized, double-blinded, placebo-controlled study demonstrates frequent incidences of both acid GER and tracheal acid aspiration during surgery that are significantly reduced by premedication with ranitidine.

Asymmetric ARDS following pulmonary resection: CT findings initial observations

PURPOSE

To investigate whether asymmetric distribution of acute respiratory distress syndrome (ARDS) following lobectomy is due to compensatory hyperexpansion of the residual lung within the hemithorax operated on and to discern if this distribution reflects true asymmetry of the disease process.

MATERIALS AND METHODS

Retrospective review of the intensive care unit database was performed over a period of 6 years to identify all cases of lung injury following lung surgery that satisfied the American-European consensus criteria for ARDS. Time to onset following surgery, time of subsequent computed tomographic (CT) examination, patient age and sex, and nature of surgery were recorded, as well as eventual patient status (ie, death or discharge). Availability of both preoperative and postoperative CT scans was required for inclusion for further analysis. These images were analyzed on a commercial CT workstation for the volume of lung resected and the pre- and postoperative volume and density of each lung. Expected postoperative densities (preoperative density adjusted for volume) were compared with observed postoperative densities.

RESULTS

Review disclosed 583 patients who underwent lobectomy or segmentectomy. Seventeen patients (2.9%) developed postoperative ARDS. Nine of these patients had pre- and postoperative CT scans available for analysis. In eight of nine cases, density increased more in the nonoperated lung than in the operated lung (P =.01). The degree of density increase in the nonoperated lung was significantly greater (305 mg/mL; range, 48-449 mg/mL) than that in the operated lung (13 mg/mL; range, -198 to 231 mg/mL; P <.001).

CONCLUSION

Following lobectomy, there appears to be a truly asymmetric form of ARDS rather than compensatory hyperexpansion of the residual lung on the operated side.

Radiographic and CT findings in complications following pulmonary resection

A variety of pulmonary resection techniques are currently available, including pneumonectomy (intrapleural, extrapleural, intrapericardial, and sleeve pneumonectomy), lobectomy, and limited resection (sleeve lobectomy, segmentectomy, nonanatomic parenchyma-sparing resection). However, pulmonary resection is often followed by postoperative complications that differ according to the type of surgery and the time elapsed since surgery was performed. The most common complications are bleeding, pulmonary edema, atelectasis, pneumonia, persistent air leak, bronchopleural fistula, and empyema. Other, less frequent complications include cardiac herniation, lung torsion, chylothorax, anastomotic dehiscence, wound infection, esophagopleural fistula, and recurrent tumor. The radiologist plays a major role in the diagnosis of various complications following pulmonary resection. Unfortunately, chest radiography has a relatively low diagnostic accuracy in the detection of these complications. When radiographic findings are subtle or equivocal, computed tomography frequently allows more accurate identification of the disease process. Several complications that follow pulmonary resection are life-threatening and require prompt management. Therefore, knowledge of the diverse radiologic appearances of these complications as well as familiarity with the clinical settings in which specific complications are likely to occur are vital for prompt, effective treatment.

Nitric oxide for the treatment of postpneumonectomy pulmonary edema

Inhaled nitric oxide, a selective pulmonary vasodilator, has been used to improve arterial oxygenation in adult respiratory distress syndrome. To our knowledge, it has not been successfully used to treat this syndrome after major lung resection. We used nitric oxide to treat postpneumonectomy pulmonary edema with immediate and sustained improvement in oxygenation. The patient was successfully weaned from nitric oxide and extubated after 3 days of supportive therapy.

Pathophysiology of Postpneumonectomy Pulmonary Edema

Pulmonary edema is a rare, potentially fatal complica tion associated with major resection of the lung, usually pneumonectomy. Although pulmonary edema in this setting can often be attributed to a variety of causes such as cardiac failure, bacterial pneumonia, and fluid overload, the specific syndrome of postpneumonec tomy pulmonary edema (PPE) occurs in the absence of these factors. PPE remains a diagnosis of exclusion, and its pathophysiology is poorly understood. Overzealous perioperative fluid administration has traditionally been implicated in clinical cases of postpneumonectomy pulmonary edema, but there is a body of evidence suggesting several other potential mechanisms. These include increases in cardiac output secondary to cat echolamine release, interruption of mediastinal lym phatic drainage, endothelial injury secondary to release of humoral factors or stretching of intercellular junc tions, hyperinflation, and other unknown factors.

Clinical and radiologic features of pulmonary edema

Pulmonary edema may be classified as increased hydrostatic pressure edema, permeability edema with diffuse alveolar damage (DAD), permeability edema without DAD, or mixed edema. Pulmonary edema has variable manifestations. Postobstructive pulmonary edema typically manifests radiologically as septal lines, peribronchial cuffing, and, in more severe cases, central alveolar edema. Pulmonary edema with chronic pulmonary embolism manifests as sharply demarcated areas of increased ground-glass attenuation. Pulmonary edema with veno-occlusive disease manifests as large pulmonary arteries, diffuse interstitial edema with numerous Kerley lines, peribronchial cuffing, and a dilated right ventricle. Stage 1 near drowning pulmonary edema manifests as Kerley lines, peribronchial cuffing, and patchy, perihilar alveolar areas of airspace consolidation; stage 2 and 3 lesions are radiologically nonspecific. Pulmonary edema following administration of cytokines demonstrates bilateral, symmetric interstitial edema with thickened septal lines. High-altitude pulmonary edema usually manifests as central interstitial edema associated with peribronchial cuffing, ill-defined vessels, and patchy airspace consolidation. Neurogenic pulmonary edema manifests as bilateral, rather homogeneous airspace consolidations that predominate at the apices in about 50% of cases. Reperfusion pulmonary edema usually demonstrates heterogeneous airspace consolidations that predominate in the areas distal to the recanalized vessels. Postreduction pulmonary edema manifests as mild airspace consolidation involving the ipsilateral lung, whereas pulmonary edema due to air embolism initially demonstrates interstitial edema followed by bilateral, peripheral alveolar areas of increased opacity that predominate at the lung bases. Familiarity with the spectrum of radiologic findings in pulmonary edema from various causes will often help narrow the differential diagnosis.

Post-pneumonectomy pulmonary edema: is anesthesia to blame?

Post-pneumonectomy pulmonary edema is a major cause of early mortality following lung resection surgery. It is not clear whether this complication is caused by excessive perioperative intravenous fluid as was previously thought. The recent demonstration of increased pulmonary capillary permeability of the lung following a pneumonectomy suggests measures to try and decrease the incidence of this highly lethal syndrome. These measures include the judicious use of intravenous crystalloids, avoidance of lung hyperinflation and efforts to minimize the pulmonary artery pressure.

Inhaled nitric oxide for adult respiratory distress syndrome after pulmonary resection

BACKGROUND

The adult respiratory distress syndrome (ARDS) developing after pulmonary resection is usually a lethal complication. The etiology of this serious complication remains unknown despite many theories. Intubation, aspiration bronchoscopy, antibiotics, and diuresis have been the mainstays of treatment. Mortality rates from ARDS after pneumonectomy have been reported as high as 90% to 100%.

METHODS

In 1991, nitric oxide became clinically available. We instituted an aggressive program to treat patients with ARDS after pulmonary resection. Patients were intubated and treated with standard supportive measures plus inhaled nitric oxide at 10 to 20 parts/million. While being ventilated, all patients had postural changes to improve ventilation/perfusion matching and management of secretions. Systemic steroids were given to half of the patients.

RESULTS

Ten consecutive patients after pulmonary resection with severe ARDS (ARDS score = 3.1+/-0.04) were treated. The mean ratio of partial pressure of arterial oxygen to the fraction of inspired oxygen at initiation of treatment was 95+/-13 mm Hg (mean +/- SEM) and improved immediately to 128+/-24 mm Hg, a 31%+/-8% improvement (p<0.05). The ratio improved steadily over the ensuing 96 hours. Chest x-rays improved in all patients and normalized in 8. No adverse reactions to nitric oxide were observed.

CONCLUSIONS

We recommend the following treatment regimen for this lethal complication: intubation at the first radiographic sign of ARDS; immediate institution of inhaled nitric oxide (10 to 20 parts per million); aspiration bronchoscopy and postural changes to improve management of secretions and ventilation/perfusion matching; diuresis and antibiotics; and consideration of the addition of intravenous steroid therapy.

The Utility of Nitric Oxide in the Postoperative Period

Inhaled nitric oxide (iNO) is a pulmonary-selective vaso dilator with minimal bronchodilator activity in humans. NO also inhibits platelet and neutrophil activation and adhesion and inhibits ischemia-reperfusion injury. The pulmonary vasodilatory property of iNO causes a reduc tion in pulmonary vascular resistance and improvement in arterial oxygenation in a wide spectrum of diseases characterized by pulmonary hypertension and hypox emia. Promising examples of diseases for which NO may provide beneficial physiologic effects are primary and secondary pulmonary hypertension, right ventricu lar failure, cardiac transplantation, pulmonary embo lism, protamine reactions, acute respiratory distress syndrome, lung transplantation and, perhaps, chronic obstructive airways disease. The usefulness of iNO may be improved by concomitant therapy with pulmonary- selective intravenous vasoconstrictors (eg, Almitrine; Vectarian, Neuilly, France) and cGMP phosphodiester ase V inhibitors (eg, Zaprinast; Research Biochemicals International, Natick, MA). Almitrine improves oxygen ation, synergistically with iNO, and may be useful in disease states characterized primarily by hypoxemia. Zaprinast may be useful for weaning iNO and avoidance of rebound pulmonary hypertension.

Postpneumonectomy pulmonary edema. A retrospective analysis of incidence and possible risk factors

OBJECTIVE

To analyze the incidence of postpneumonectomy pulmonary edema (PPE) and to determine potential risk factors for PPE.

MATERIAL AND METHODS

A group of 197 patients was studied retrospectively, and the incidence of PPE was recorded over a 5-year period. Preoperative, perioperative, and postoperative clinical data were collected, and preoperative and postoperative chest radiographs were reviewed. A scoring system was used to distinguish between premanifest and manifest PPE. Postpneumonectomy patients with pulmonary edema, with no clinically evident cause, were considered to have PPE.

RESULTS

The incidence of premanifest PPE was 12.2% (n = 24), and that of manifest PPE was 2.5% (n = 5). Mortality in the group of patients who developed manifest PPE was 100%. Two significant perioperative associations were found in the PPE group. One was the administration of fresh frozen plasma (FFP) transfusions (relative risk, 4.3; 95% confidence interval, 1.3 to 14.4 corrected for age and sex), while the other was higher mechanical ventilation pressures during surgery (relative risk, 3.0; 95% confidence interval, 1.2 to 7.3).

CONCLUSION

Our data suggest that FFP transfusions form an important risk factor for PPE. The mechanism may be an increased permeability of the pulmonary vessels due to an immunologic reaction after multiple FFP transfusions. The significantly higher mechanical ventilation pressures we found in the PPE group may be explained as an early sign of the development of PPE.

Video-assisted thoracoscopic volume reduction surgery in patients with diffuse pulmonary emphysema: gas exchange and anesthesiological management

Arterial blood gases were studied prospectively using continuous intraarterial blood gas monitoring during thoracoscopic volume reduction surgery (VRS) in 24 patients with advanced diffuse pulmonary emphysema. Additionally, the early postoperative course (48 h) of arterial blood gases was studied retrospectively. Twenty-six operations were performed using a combination of thoracic epidural and general anesthesia with left-sided double-lumen intubation for one-lung ventilation (OLV). Arterial blood gases were determined awake, during two-lung ventilation prior to surgery, during OLV (extreme values), and after tracheal extubation. Additionally, the extremes during the whole procedure were determined: avoiding excessive peak inspiratory pressures (26.4 +/- 7.0 cm H2O), minimum PaO2 was 77 +/- 39 mm Hg (mean +/- SD), maximum PaCO2 65 +/- 14 mm Hg (P < 0.0001 versus preoperative values), and minimum pHa 7.22 +/- 0.08 (P < 0.0001). One tension pneumothorax occurred during OLV. Immediate postoperative extubation was performed in 25 of 26 cases, reintubation was necessary in two cases. One patient with coronary artery disease died 36 h after surgery. Hypercapnia (maximum PaCO2 49 +/- 8 mm Hg, minimum pHa 7.37 +/- 0.04, P < 0.01) was still observed 48 h after surgery. These results demonstrate that adequate oxygenation can be preserved during OLV for VRS, but CO2 elimination is impaired. However, intraoperative hypercapnia and immediate postoperative tracheal extubation are well tolerated.

[Recording effective capillary pressure: a useful technique in post-pneumonectomy edema]

Three cases of postpneumonectomy edema, in which hemodynamic stability was monitored with a Swan-Ganz catheter, are described. Measurement of pressure in the pulmonary capillary was based on the pulmonary artery occlusion curve. High capillary pressure and normal wedge pressure were observed in all 3 cases, suggesting that the rise in net filtration pressure as a consequence of excess flow is the pathogenic mechanism that triggers edema after pneumonectomy. We emphasize that measurement of effective pulmonary capillary pressure allows for more accurate assessment of the hemodynamic status of such patients than does the measurement of wedge pressure.

Pulmonary endothelial permeability changes after major lung resection

BACKGROUND

Increased pulmonary endothelial permeability has been proposed as a cause of postpneumonectomy pulmonary edema. This study investigated changes in pulmonary endothelial permeability after major lung resection.

METHODS

Lung scintigraphy was performed in 21 men (median age, 66 years; range, 34 to 73 years) after pneumonectomy (10 patients) or lobectomy (11 patients). Pulmonary endothelial permeability was measured by the net pulmonary accumulation of intravenous technetium-99m-labeled albumin, calculated as a ratio of lung:heart radioactivity counts. Pulmonary hemodynamics were monitored continuously by a pulmonary artery catheter, and serum levels of inflammatory cytokines were assayed.

RESULTS

The lung:heart radioactivity ratio increased significantly in the initial 8 hours after pneumonectomy but not after lobectomy (p < 0.01). Mean pulmonary artery pressure and pulmonary vascular resistance both increased significantly during pneumonectomy (p < 0.05). The intraoperative increase in mean pulmonary artery pressure was inversely related to preoperative mean pulmonary artery pressure (r = -0.47; p = 0.02). The postoperative change in lung:heart radioactivity ratio to the perioperative increase in pulmonary vascular resistance (r = 0.54; p = 0.02) but not to the increase in mean pulmonary artery pressure (r = 0.14; p > 0.05). Serum interleukin-8 and neutrophil elastase levels were elevated in all patients preoperatively. The postoperative change in lung:heart radioactivity ratio was related to preoperative elastase levels (r = 0.61; p = 0.02).

CONCLUSIONS

Pulmonary endothelial permeability appears to be increased after pneumonectomy. Preoperative neutrophil activation and the adaptation of the remaining pulmonary vasculature may be etiologic factors.

Acute lung injury following lung resection: is one lung anaesthesia to blame?

Further examination of the parameters of oxidative stress, perioperative changes in the vasoregulatory mechanisms of the pulmonary circulation, and characterisation of the endothelial insult that probably occurs in all patients undergoing lung resection is necessary if the operative conditions under which lung surgery is carried out are to be optimised. Perhaps, then, more insight might be gained into how to improve preservation of lungs for transplantation and how to protect the lung from significant injury following resection.

Lung injury in patients following thoracotomy

BACKGROUND

Postoperative lung injury is a recognised complication of thoracotomy for which there are few data regarding incidence and outcome.

METHODS

In a case controlled study the notes of all adult patients who developed acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) following thoracotomy between 1991 and 1994 were examined and classified according to the guidelines of the American Thoracic Society/European Respiratory Society for ALI/ARDS. The predictive value of a routine preoperative assessment and duration of anaesthesia in determining those patients most likely to develop ALI/ARDS was assessed.

RESULTS

Between 1991 and 1994 231 lobectomies, 103 pneumonectomies, and 135 wedge resections and segmentectomies were performed. The overall incidence of lung injury was 5.1%; 17 patients developed ARDS (two survived) and seven developed ALI (five survived). There was no significant difference compared with case matched controls in preoperative spirometric values, arterial oxygen tension (PaO2), or duration of anaesthesia. None of these parameters was useful in predicting those patients most likely to develop lung injury.

CONCLUSION

Lung injury after thoracotomy is associated with a high mortality. Conventional parameters for preoperative assessment do not predict those patients most likely to develop ALI/ARDS in these circumstances.

Postpneumonectomy pulmonary edema

Pulmonary edema is an uncommon but serious complication associated with major resection of the lung, usually after pneumonectomy. The pathophysiology of this condition is not completely understood, but recent experimental and clinical data suggest that this condition results from a combination of increased filtration gradient across the pulmonary microcirculation together with hyperpermeability. Overzealous perioperative infusions of fluid have been implicated in clinical cases. We present the reports of 2 patients with postpneumonectomy pulmonary edema we recently encountered and a review of the literature to provide diagnostic and therapeutic guidelines in dealing with this serious complication.