Gas exchange and pulmonary hemodynamics during lung resection in patients at increased risk: relationship with preoperative exercise testing

Preoperative Evaluation of Patients Submitted to Pneumonectomy for Lung Carcinoma: Role of Exercise Testing

The aim of the present investigation was to evaluate which parameters of preoperative spirometry, arterial blood gas, radionuclide lung scanning and cardiopulmonary exercise test are the best predictor of postoperative morbidity and mortality in patients submitted to pneumonectomy. The study was conducted in 150 patients (mean age, 57.1). Forty-four patients (29.3%) had postoperative complications. Four patients (2.7%) died within one month of the pneumonectomy. Patients with complications had significantly lower ppoFEV1 as percentage of predicted and lower VO2 max, and those who died also had a significant decrease in PaO2 during exercise. Moreover, among patients with obstructive pulmonary disease (FEV1<70% of predicted), we found a significantly higher percentage predicted residual volume and a significantly lower VO2 max in complicated patients. The present data support the suggestion that exercise testing could be a useful adjunt in the evaluation of postoperative risk for pneumonectomy, especially in patients with obstructive pulmonary disease. In particular, patients with VO2 max <50% of predicted should be considered at high risk of morbidity from cardiopulmonary causes.

Pulmonary hemodynamic profile in chronic obstructive pulmonary disease

Introduction

Few data are available in regards to the prevalence of pulmonary hypertension (PH) in the broad spectrum of COPD. This study was aimed at assessing the prevalence of PH in a cohort of COPD patients across the severity of airflow limitation, and reporting the hemodynamic characteristics at rest and during exercise.

Methods

We performed a retrospective analysis on COPD patients who underwent right-heart catheterization in our center with measurements obtained at rest (n=139) and during exercise (n=85). PH was defined as mean pulmonary artery pressure (mPAP) ≥25 mmHg and pulmonary capillary wedge pressure <15 mmHg. Exercise-induced PH (EIPH) was defined by a ratio of ΔmPAP/Δcardiac output >3.

Results

PH was present in 25 patients (18%). According to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification, PH prevalence in GOLD 2 was 7% (3 patients); 25% (14 patients) in GOLD 3; and 22% (8 patients) in GOLD 4. Severe PH (mPAP ≥35 mmHg) was identified in four patients (2.8%). Arterial partial oxygen pressure was the outcome most strongly associated with PH (r=−0.29, P<0.001). EIPH was observed in 60 patients (71%) and had a similar prevalence in both GOLD 2 and 3, and was present in all GOLD 4 patients. Patients with PH had lower cardiac index during exercise than patients without PH (5.0±1.2 versus 6.7±1.4 L/min/m², respectively; P=0.001).

Conclusion

PH has a similar prevalence in COPD patients with severe and very-severe airflow limitation, being associated with the presence of arterial hypoxemia. In contrast, EIPH is highly prevalent, even in moderate COPD, and might contribute to limiting exercise tolerance.

Preoperative pulmonary vascular morphology and its relationship to postpneumonectomy hemodynamics

RATIONALE AND OBJECTIVES

Pulmonary edema and pulmonary hypertension are postsurgical complications of pneumonectomy that may represent the remaining pulmonary vasculature's inability to accommodate the entirety of the cardiac output. Quantification of the aggregate pulmonary vascular cross-sectional area (CSA) has been used to study the development of pulmonary vascular disease in smokers. In this study, we applied this technique to demonstrate the potential utility of pulmonary vascular quantification in surgical risk assessment. Our hypothesis was that those subjects with the lowest aggregate vascular CSA in the nonoperative lung would be most likely to have elevated pulmonary vascular pressures in the postoperative period.

MATERIALS AND METHODS

A total of 61 subjects with postoperative hemodynamics and adequate imaging were identified from 159 patients undergoing pneumonectomies for mesothelioma. The total CSA of blood vessels perpendicular to the plane of computed tomographic (CT) scan slices was computed for blood vessels <5 mm(2) (CSA 5 mm). This measurement expressed as a percentage of lung parenchyma area (CSA 5%) was compared to postoperative hemodynamic measurements obtained by right heart catheterization.

RESULTS

In patients where a contrasted CT scan was used (n = 26), CSA 5% was correlated with postoperative day 0 minimum cardiac index (R = 0.37, P = .03) but not with the maximum pulmonary arterial pressures. In patients with noncontrast CT scans (n = 35), CSA 5% was inversely correlated with postoperative day 0 maximum pulmonary arterial pressures (R = 0.43, P = .03) but not with the minimum cardiac index. The preoperative perfusion fraction of the nonsurgical lung did not correlate with postoperative hemodynamics.

CONCLUSIONS

CSA of pulmonary vasculature with an area ≤5 mm(2) has potential in estimating the ability of pulmonary vascular bed to accommodate postsurgical changes in pneumonectomy.

Monitoring of exhaled carbon monoxide and carbon dioxide during lung cancer operation

OBJECTIVE

Carbon monoxide (CO) is expelled mainly via the lungs, so that exhaled carbon monoxide (Ex-CO) concentration reflects endogenous production. Recent reports have shown that Ex-CO levels are increased in critically ill patients and after anaesthesia and surgery. However, there has been no investigation of the changes in Ex-CO level during a lung operation. We continuously monitored Ex-CO and exhaled carbon dioxide (Ex-CO2) concentrations during surgery for lung cancer.

METHODS

Eighteen lung cancer patients who underwent elective lung cancer lobectomy were enrolled in this study. All patients were endotracheally intubated and ventilated under general anaesthesia. Ex-CO and Ex-CO2 concentrations were separately monitored and recorded continuously using two sets of Carbolyzer® breath analysers (Taiyo Inc., Osaka, Japan).

RESULTS

Ex-CO concentration increased rapidly in response to changes in body position from supine to decubitus and was significantly decreased when patients were once again lying back (supine 2). Upon restarting bilateral ventilation, Ex-CO concentration in the operated lung was significantly higher than that in the breathing lung. In the lateral decubitus position, Ex-CO2 concentration showed the same pattern of increase as seen for Ex-CO. In the operated lung, the Ex-CO2 concentrations changed significantly at clamping, declamping and supine 2. In the re-ventilated, operated lung, the Ex-CO2 concentration was significantly lower than in the breathing lung. In the breathing lung, the Ex-CO2 concentration did not exhibit any significant changes over the course of the operation.

CONCLUSIONS

When breathing was restarted, the Ex-CO level of the target lung was significantly higher than that of the breathing lung. The Ex-CO concentration was also affected by the surgical body position and this change was marked and transient.

Changes in cerebral oxygenation in patients with pulmonary dysfunction after lung resection

Lung resection would be associated with lower jugular bulb oxygen saturation (SjvO₂) values in patients with moderate to severe pulmonary dysfunction. We aimed to study the effects of lung resections on the postoperative changes in SjvO₂, incidence of SjvO₂ < 50%, pulmonary functions, cerebral blood flow equivalent (CBFE), and arterial to jugular difference in oxygen content (AjvDO₂) in the patients with pulmonary dysfunction. Fifty-three patients scheduled for lung resection were allocated on the basis of forced vital capacity (FVC %) and forced expiratory volume in 1 second (FEV(1)%) into the following: good FVC and FEV₁ (n = 14), mild (n = 14), moderate (n = 13), and severe (n = 12) pulmonary dysfunction groups. After lung resections, patients with pulmonary dysfunctions had significantly lower SjvO₂, CBFE, FEV₁, and FVC (P < .001), higher AjvDO₂ (P < .001), and frequent episodes with SjvO₂ < 50% (P < .03). Perioperative changes in FEV₁ had a significant negative correlation with SjvO₂ desaturation (P < .002). Patients with pulmonary dysfunction showed significant SjvO₂ < 50% after lung resection, which is correlated to the perioperative changes in FEV₁.

Nuclear factor-kappa B mediates one-lung ventilation-induced acute lung injury in rabbits

INTRODUCTION

Several studies have revealed the adverse effect of one-lung ventilation (OLV) on pulmonary function. Nuclear factor-kappa B (NF-κB) is a principal transcription factor of proinflammatory genes. This study was designed to investigate the role of NF-κB in OLV-mediated lung injury.

METHODS

Male rabbits, weighing 2.2 ± 0.3 kg, were randomly divided into five groups: sham tracheostomized (Sham), OLV (V(T) = 10 ml/kg, FiO(2) = 1.0), two-lung ventilation (TLV, V(T) = 10 ml/kg, FiO(2) = 1.0), OLV preceded by the treatment with NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC, 50 mg/kg, i.v.), and TLV with the PDTC pretreatment. Arterial blood gases, lung pathological changes, and production of proinflammatory cytokines (tumor necrosis factor-α and interleukin-8) were assessed. NF-κB activation was determined by electrophoretic mobility shift assay (EMSA) and western blotting of nuclear NF-κB p65.

RESULTS

The OLV significantly decreased the ratio of partial pressure of oxygen and fraction inspired oxygen (PaO(2)/FiO(2)) compared to the Sham group (p < .01). However, the TLV had no evident effect on the PaO(2)/FiO(2) ratio. The pretreatment with PDTC significantly reversed the OLV-induced reduction in the PaO(2)/FiO(2) ratio. The PDTC pretreatment also markedly attenuated the OLV-mediated lung injury and proinflammatory cytokine production. The OLV potentiated the NF-κB DNA binding activity assessed by EMSA and the NF-κB nuclear translocation. The OLV-mediated NF-κB activation was markedly inhibited by the PDTC pretreatment.

CONCLUSION

Our data collectively demonstrate that OLV can cause lung injury through the activation of NF-κB and the production of proinflammatory cytokines. Blocking NF-κB reduces lung inflammation and may be an effective strategy in the management of OLV-induced lung damage.

Comparison of two protective lung ventilatory regimes on oxygenation during one-lung ventilation: a randomized controlled trial

BACKGROUND

The efficacy of protective ventilation in acute lung injury has validated its use in the operating room for patients undergoing thoracic surgery with one-lung ventilation (OLV). The purpose of this study was to investigate the effects of two different modes of ventilation using low tidal volumes: pressure controlled ventilation (PCV) vs. volume controlled ventilation (VCV) on oxygenation and airway pressures during OLV.

METHODS

We studied 41 patients scheduled for thoracoscopy surgery. After initial two-lung ventilation with VCV patients were randomly assigned to one of two groups. In one group OLV was started with VCV (tidal volume 6 mL/kg, PEEP 5) and after 30 minutes ventilation was switched to PCV (inspiratory pressure to provide a tidal volume of 6 mL/kg, PEEP 5) for the same time period. In the second group, ventilation modes were performed in reverse order. Airway pressures and blood gases were obtained at the end of each ventilatory mode.

RESULTS

PaO2, PaCO2 and alveolar-arterial oxygen difference did not differ between PCV and VCV. Peak airway pressure was significantly lower in PCV compared with VCV (19.9 ± 3.8 cmH2O vs 23.1 ± 4.3 cmH2O; p < 0.001) without any significant differences in mean and plateau pressures.

CONCLUSIONS

In patients with good preoperative pulmonary function undergoing thoracoscopy surgery, the use of a protective lung ventilation strategy with VCV or PCV does not affect the oxygenation. PCV was associated with lower peak airway pressures.

Risk factor analysis for postoperative acute respiratory distress syndrome and early mortality after pneumonectomy: the predictive value of preoperative lung perfusion distribution

OBJECTIVES

This study aims to establish the preoperative risk factors in the development of acute respiratory distress syndrome (ARDS) and early mortality after pneumonectomy for lung cancer and to examine the influence of reduced pulmonary perfusion on outcomes.

METHODS

Between 1994 and 2009, of 425 patients who underwent simple pneumonectomy for primary lung cancer, 164 who were preoperatively evaluated with lung perfusion scanning formed the population of this study.

RESULTS

Of 30 (18.3%) patients who had major pulmonary complications, 17 (10.4%) progressed to ARDS, 15 of whom subsequently died. On multivariable logistic regression analyses, lower predicted postoperative forced expiratory volume in 1 second (ppo-FEV(1); relative risk of 0.93 [P = .020] for ARDS and 0.94 [P = .027] for mortality) and greater perfusion fraction of resected lung (relative risk of 1.10 [P = .003] for ARDS and 1.09 [P = .002] for mortality) were found to be independent factors associated with ARDS and early mortality. With a cut-off value of 35% for perfusion fraction of resected lung, patients with a perfusion fraction of greater than 35% had a greater incidence of ARDS (17.3% vs 3.3%, P = .005) and early mortality (19.8% vs 6.0%, P = .010) than those with a perfusion fraction of 35% or less.

CONCLUSIONS

Patients with a low ppo-FEV(1), a high perfusion fraction of resected lung, or both had a higher incidence of ARDS and early mortality after pneumonectomy. Therefore, although the ppo-FEV(1) appears to be within an acceptable limit for pneumonectomy, much attention should be given to patients with a high perfusion fraction of resected lung.

Effects of Arginine Vasopressin on Oxygenation and Haemodynamics during One-Lung Ventilation in an Animal Model

In a case of arterial hypotension during one-lung ventilation, haemodynamic support may be required to maintain adequate mean arterial pressure. Arginine vasopressin, a potent systemic vasoconstrictor with limited effects on the pulmonary artery pressure, has not been studied in this setting. Twelve female pigs were anaesthetised and ventilated and arterial, central venous and pulmonary artery catheters were inserted. A left-sided double lumen tube was placed via tracheostomy and one-lung ventilation was initiated. The animals were in the left lateral position, with the left lung ventilated and right lung collapsed. Respiratory and haemodynamic values were recorded before and during a continuous infusion of arginine vasopressin sufficient to double the mean arterial pressure. The arginine vasopressin caused a decrease in cardiac output (3.8±1.1 vs. 2.7±0.7 l/min, P <0.001) and mixed-venous oxygen tension (39.1±5.8 vs. 34.4±5 mmHg, P=0.003). Pulmonary artery pressure was unchanged (24±2 vs. 24±3 mmHg, P=0.682). There was no effect of the arginine vasopressin on arterial oxygen tension (226±106 vs. 231±118 mmHg, P=0.745). However, there was a significant decrease in shunt fraction (28.3±6.2 vs. 24.3±7.8%, P=0.043) and a significant proportional increase in perfusion of the ventilated lung (78.8±9.5 vs. 85.5±7.9%, P=0.036). In our animal model of one-lung ventilation, doubling mean arterial pressure by infusion of arginine vasopressin significantly affected global haemodynamics, but had no influence on systemic arterial oxygen tension.

Surgical treatment of patients with lung cancer and limited lung function: Preoperative assessment, operative mortality and morbidity

Introduction: Lung resection in patients with limited lung function is one of the greatest challenges in general thoracic surgery. Objective. The aim of the study was to analyze the pattern of lung function changes after operation, operative morbidity and mortality and to compare them with control group of patients. Method. The study included 34 patients with limited lung function, operated for primary lung cancer in one-year period. All patients underwent preoperative desobstructive treatment. The type of ventilatory disorder was analyzed depending on preoperative radiographic and bronchoscopic aspect. Statistics: chisquare test, t-test. Results. In patients with lobectomy, the mean difference in forced expiratory volume in the first second (FEV1) between preoperative and postoperative values was 16.81%, whilst in the pneumonectomy group this difference was 39.51%. The mean change in forced vital capacity (FVC) in the lobectomy and pneumonectomy group was 15.83% and 42.73% respectively. In the control group of 28 patients with lobectomy, the decrease in FVC and FEV1 was 19.9% and 24.18% respectively. In the control group of 28 patients with pneumonectomy, the decrease in FVC and FEV1 was 43.52% and 41.36% respectively. In patients with limited lung function and lobectomy, changes in FEV1 and VC after resection were significantly lower compared to the control group of patients with lobectomy and normal lung function. None of 34 operated patients with borderline lung function died inside 30 postoperative days. In the same period, of a total number of 344 patients without respiratory function impairment, operative mortality was 3.1%. In the analyzed group, operative morbidity was 32.35%. Cardiovascular and respiratory complications in the analyzed and control groups occurred in 14.7% and 6.1% of patients respectively (p>0.05). Conclusion. Surgery should not be excluded in patients with borderline lung function prior to preoperative treatment and additional lung function assessment. .

Surgical lung cancer

STUDY OBJECTIVE

To identify those variables that are associated with operative morbidity or mortality in cases of thoracotomy in lung cancer.

SETTING

Third level university hospital.

PATIENTS

Consecutive patients with thoracotomy due to lung cancer operated on between 1994 and 1997 (n = 115).

METHODS

Pre- and postoperative variables potentially associated with operative morbidity or mortality were retrieved prospectively as follows: demographic and clinical characteristics of the patients, cardiopulmonary function characteristics, tumour characteristics, and treatment characteristics. A bivariate analysis of all variables under evaluation was carried out in order to identify those variables associated with operative morbidity and mortality. A multivariable analysis of the selected variables was then conducted using a logistic model.

RESULTS

The predicted postoperative product (predicted FEV1 x predicting diffusing capacity of carbon monoxide), the carbon monoxide diffusion coefficient (Kco) and the contralateral pulmonary perfusion are variables that relate to the overall morbidity or mortality (number of events 63, 55%) (-2 log likelihood chi2 = 22.9; R2 = 0.27). For variables associated with postoperative morbidity, the best associative model combines functional variables (diffusion, predicted FEV1), endoscopic variables (obstructed segments to be resected), clinical variables (comorbidity) and an important postoperative variable, the pathological tumoural staging (pN) (number of events 49, 43%) (-2 log likelihood chi2 = 32.9; R2 = 0.36).

CONCLUSION

The numerous variables under analysis are poorly associated with morbidity or mortality after thoracotomy in lung cancer. With regard to postoperative morbidity, the best associative models combine information that is known pre- and postoperatively and which is provided by both the patient and the tumour.

One-lung ventilation with high tidal volumes and zero positive end-expiratory pressure is injurious in the isolated rabbit lung model

We tested the hypothesis that one-lung ventilation (OLV) with high tidal volumes (VT) and zero positive end-expiratory pressure (PEEP) may lead to ventilator-induced lung injury. In an isolated, perfused rabbit lung model, VT and PEEP were set to avoid lung collapse and overdistension in both lungs, resulting in a straight pressure-time (P-vs-t) curve during constant flow. Animals were randomized to (a) nonprotective OLV (left lung) (n = 6), with VT values as high as before randomization and zero PEEP; (b) protective OLV (left lung) (n = 6), with 50% reduction of VT and maintenance of PEEP as before randomization; and (c) control group (n = 6), with ventilation of two lungs as before randomization. The nonprotective OLV was associated with significantly smaller degrees of collapse and overdistension in the ventilated lung (P < 0.001). Peak inspiratory pressure values were higher in the nonprotective OLV group (P < 0.001) and increased progressively throughout the observation period (P < 0.01). The mean pulmonary artery pressure and lung weight gain values, as well as the concentration of thromboxane B(2), were comparatively higher in the nonprotective OLV group (P < 0.05). A ventilatory strategy with VT values as high as those used in the clinical setting and zero PEEP leads to ventilator-induced lung injury in this model of OLV, but this can be minimized with VT and PEEP values set to avoid lung overdistension and collapse.

IMPLICATIONS

One-lung ventilation with high tidal volumes and zero positive end-expiratory pressure (PEEP) is injurious in the isolated rabbit lung model. A ventilatory strategy with tidal volumes and PEEP set to avoid lung overdistension and collapse minimizes lung injury during one-lung ventilation in this model.