Misleading "pulmonary wedge pressure" after pneumonectomy: its importance in postoperative fluid therapy

Literature and new innovations leading to the rise and fall of the Swan-Ganz catheter

BACKGROUND

In 1970, Harold James Charles Swan and William Ganz published their work on the pulmonary artery catheter (PAC or Swan-Ganz catheter). They described the successful bedside use of a flow-directed catheter to continuously evaluate the heart, and it was used extensively in the years following to care for critically ill patients. In recent decades, clinicians have reevaluated the risks and benefits of the PAC.

AIM

We acknowledge the contributions of Swan and Ganz and discuss literature, including randomized controlled trials, and new technology surrounding the rise and fall in use of the PAC.

METHODS

We performed a literature search of retrospective and prospective studies, including randomized controlled trials, and editorials to understand the history and clinical outcomes of the PAC.

RESULTS

In the 1980s, clinicians began to question the benefits of the PAC. In 1996 and 2003, a large observational study and randomized controlled trial, respectively, showed no clear benefits in outcome. Thereafter, use of PACs began to drop precipitously. New less and noninvasive technology can estimate cardiac output and blood pressure continuously.

CONCLUSIONS

Swan and Ganz contributed to the bedside understanding of the pathophysiology of the heart. The history of the rise and fall in use of the PAC parallels the literature and invention of less-invasive technology. Although the PAC has not been shown to improve clinical outcomes in large randomized controlled trials, it may still be useful in select patients. New less-invasive and noninvasive technology may ultimately replace it if literature supports it.

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.

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.

Anesthetic management of patients undergoing extrapleural pneumonectomy for mesothelioma

PURPOSE OF REVIEW

Extrapleural pneumonectomy is a radical and aggressive surgery that presents a great challenge to the thoracic anesthesiologist. This surgery is performed routinely by only a few centers in the world and this review represents our institution's experience in anesthetic care.

RECENT FINDINGS

Prominent among the developing multimodal treatment options is the combination of extrapleural pneumonectomy with intraoperative intracavitary hyperthermic chemotherapy. Outcome survival benefits have recently been demonstrated for the less completely cytoreductive pleurectomy procedure when combined with intraoperative intracavitary hyperthermic chemotherapy and trials are well under way for extrapleural pneumonectomy plus intraoperative intracavitary hyperthermic chemotherapy. Anesthetic management of extrapleural pneumonectomy is further impacted by these developments.

SUMMARY

Anesthetic management importantly contributes to containment of the perioperative complications of extrapleural pneumonectomy. An appreciation of the technical aspects and physiologic disruptions associated with extrapleural pneumonectomy is critical to effective management. While data on this relatively uncommon surgical procedure are scarce, some referral centers have accumulated extensive experience. This review summarizes relevant surgical aspects and anesthetic insights from the Brigham and Women's Hospital experience. Included are the anesthetic implications of intraoperative intracavitary hyperthermic chemotherapy in combination with extrapleural pneumonectomy - an emerging therapeutic option in the treatment of malignant pleural mesothelioma.

Extravascular lung water after pneumonectomy and one-lung ventilation in sheep

OBJECTIVE

To compare the single thermodilution and the thermal-dye dilution techniques with postmortem gravimetry for assessment of changes in extravascular lung water after pneumonectomy and to explore the evolution of edema after injurious ventilation of the left lung.

DESIGN

Experimental study.

SETTING

University laboratory.

SUBJECTS

A total of 30 sheep weighing 35.6 +/- 4.6 kg. The study included two parts: a pneumonectomy study (n = 18) and an injurious ventilation study (n = 12).

METHODS

Sheep were anesthetized and mechanically ventilated with an FiO2 of 0.5, tidal volume of 6 mL/kg, and positive end-expiratory pressure of 2 cm H2O. In the pneumonectomy study, sheep were assigned to right-sided pneumonectomy (n = 7), left-sided pneumonectomy (n = 7), or lateral thoracotomy only (sham operation, n = 4). In the injurious ventilation study, right-sided pneumonectomy was followed by ventilation with a tidal volume of 12 mL/kg and positive end-expiratory pressure of 0 cm H2O (n = 6) or by ventilation with a tidal volume of 6 mL/kg and positive end-expiratory pressure of 2 cm H2O for 4 hrs (n = 6). Volumetric variables, including extravascular lung water index (EVLWI), were measured with single thermodilution (STD; EVLWI(STD)) and thermal-dye dilution (TDD; EVLWI(TDD)) techniques. We monitored pulmonary hemodynamics and respiratory variables. After the sheep were killed, EVLWI was determined for each lung by gravimetry (EVLWI(G)).

RESULTS

In total, the study yielded strong correlations of EVLWI(STD) and EVLWI(TDD) with EVLWI(G) (n = 30; r = .83 and .94, respectively; p < .0001). After pneumonectomy, both the left- and the right-sided pneumonectomy groups displayed significant decreases in EVLWI(STD) and EVLWI(TDD). The injuriously ventilated sheep demonstrated significant increases in EVLWI that were detected by both techniques. The mean biases (+/-2 SD) compared with EVLWI(G) were 3.0 +/- 2.6 mL/kg for EVLWI(STD) and 0.4 +/- 1.6 mL/kg for EVLWI(TDD).

CONCLUSIONS

After pneumonectomy and injurious ventilation of the left lung, TDD and STD displayed changes in extravascular lung water with acceptable accuracy when compared with postmortem gravimetry. Ventilator-induced lung injury seems to be a crucial mechanism of pulmonary edema after pneumonectomy.

Acute lung injury and acute respiratory distress syndrome after pulmonary resection

The occurrence of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) after thoracic surgery are perplexing and persistent problems. Variously described as postpneumonectomy pulmonary edema, noncardiogenic pulmonary edema, and postlung resection pulmonary edema, ALI and ARDS may be considered a single entity, with ALI being the less severe form of ARDS. It is characterized by the acute onset of hypoxemia with radiographic infiltrates consistent with pulmonary edema, without elevations in the pulmonary capillary wedge pressure. Although this syndrome does not occur frequently and is usually without identifiable cause, the mortality is high. However, the phenomenon has not been rigorously studied owing to the low incidence, with primarily retrospective case series reported. Thus, the nomenclature, risks, and pathogenesis are not well defined. Interest in this syndrome has recently been renewed as the rate of other perioperative complications has declined. ALI/ARDS is reviewed with a focus on potential etiologies and the spectrum of available interventions.

Anesthetic Considerations for Lung Volume Reduction Surgery and Lung Transplantation

Anesthetic considerations for lung transplantation and LVRS have been reviewed, with an emphasis on critical intraoperative junctures and decision points. Cognizance of these issues promotes coordinated and optimal care and provides the potential to improve outcome in this particularly high-risk population.

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.

Preload indexes in thoracic anesthesia

PURPOSE OF THE REVIEW

An adequate cardiac preload is essential in the treatment of critically ill patients. During anesthesia for thoracic surgery, volume and vasoactive therapy to optimize cardiac output, oxygen delivery (tissue perfusion) and to avoid pulmonary edema is a central therapeutic aspect. Cardiac preload has been estimated with different techniques in clinical practice, even though studies performed on thoracic anesthesia are lacking.

RECENT FINDINGS

We analyze the conventional pulmonary artery catheter, transesophageal echocardiography and the transpulmonary indicator dilution technique as preload monitoring devices with their indications and limits in thoracic anesthesia.

SUMMARY

The pulmonary artery catheter is confirmed as a fundamental device particularly in patients with pulmonary hypertension. For transesophageal echocardiography monitoring, the dependency on operator experience, the low repeatability and the high costs limit its interpretation and diffusion in clinical practice. During lung transplantation, Swan Ganz catheter monitoring is recommended. The optimization of fluid balance and vasoactive drug administration based on volumetric monitoring makes the transpulmonary indicator dilution technique a new option as an effective monitoring system during anesthesia for thoracic surgery when intravascular volume management is a primary objective.

Preload index: pulmonary artery occlusion pressure versus intrathoracic blood volume monitoring during lung transplantation

In this study, during lung transplantation, we analyzed a conventional preload index, the pulmonary artery occlusion pressure (PAOP), and a new preload index, the intrathoracic blood volume index (ITBVI), derived from the single-indicator transpulmonary dilution technique (PiCCO System), with respect to stroke volume index (SVIpa). We also evaluated the relationships between changes (Delta) in ITBVI and PAOP and DeltaSVIpa during lung transplantation. The reproducibility and precision of all cardiac index measurements obtained with the transpulmonary single-indicator dilution technique (CIart) and with the pulmonary artery thermodilution technique (CIpa) were also determined. Measurements were made in 50 patients monitored with a pulmonary artery catheter and with a PiCCO System at six stages throughout the study. Changes in the variables were calculated by subtracting the first from the second measurement (Delta(1)) and so on (Delta(1) to Delta(5)). The linear correlation between ITBVI and SVIpa was significant (r(2)=0.41; P < 0.0001), whereas PAOP poorly correlated with SVIpa (r(2) = -0.01). Changes in ITBVI correlated with changes in SVIpa (Delta(1), r(2) = 0.30; Delta(2), r(2) = 0.57; Delta(4), r(2) = 0.26; and Delta(5), r(2) = 0.67), whereas PAOP failed. The mean bias between CIart and CIpa was 0.15 l. min(-1). m(-2) (1.37). In conclusion, ITBVI is a valid indicator of cardiac preload and may be superior to PAOP in patients undergoing lung transplantation.

IMPLICATIONS

The assessment of intrathoracic blood volume index (ITBVI) by the transpulmonary single-indicator technique is a useful tool in lung transplant patients, providing a valid index of cardiac preload that may be superior to pulmonary artery occlusion pressure. However, more prospective, randomized studies are necessary to evaluate the role and limitations of this technique.

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.

Pathogenesis and management of respiratory insufficiency following pulmonary resection

The underlying principle of the surgical treatment of non-small-cell lung cancer (NSCLC) is complete removal of the local/regional disease within the thorax. Pulmonary resection should be as conservative as possible without compromising the adequacy of tumor removal. A multitude of factors influence the incidence and severity of complications following pulmonary resection including the pre-operative physical and psychological status of the patient, the pathologic process requiring resection, the physiologic impact of the procedure, and the addition of pre-operative or postoperative adjuvant therapy. The insidious onset of interstitial changes on chest X-ray (CXR) 1 to 2 days after pulmonary resection forewarns of respiratory distress; however, the pathophysiology of adult respiratory distress syndrome (ARDS) with progression to respiratory failure requiring mechanical ventilation and advanced critical care often unfolds. Management of patients with severe respiratory failure remains primarily supportive. "Good critical care" is the mainstay of therapy: this includes gentle mechanical ventilation to avoid ventilator-induced barotrauma and over-extension of remaining functional alveoli, diuresis, infection identification and management, and nutritional support. New therapeutic strategies that may impact on outcomes in the adult population include pressure-limited ventilation (permissive hypercapnia), inverse ratio ventilation, high-frequency jet ventilation, high-frequency oscillatory ventilation, intratracheal pulmonary ventilation, and prone position ventilation. In addition, alternative therapies such as partial liquid ventilation, inhaled nitric oxide, and extracorporeal techniques including extracorporeal membrane oxygenation (ECMO), extracorporeal carbon dioxide removal (ECCO(2)R), intravascular oxygenation (IVOX), and arteriovenous carbon dioxide removal (AVCO(2)R), provide additional modalities. A component of some or all of these strategies is finding a role in clinical practice.

Acute lung injury and acute respiratory distress syndrome after pulmonary resection

BACKGROUND

In this study we investigate the frequency and mortality of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) after pulmonary resection.

METHODS

Patients that underwent pulmonary resection at the Royal Brompton Hospital between 1991 and 1997 were included. The case notes of all patients developing postoperative complications were retrospectively reviewed.

RESULTS

The overall combined frequency of ALI and ARDS was 3.9%. The frequency was higher in patients over 60 years of age, males and those undergoing resection for lung cancer. ALI/ARDS caused 72.5% of the total mortality after resection in this series.

CONCLUSIONS

In our experience ALI and ARDS are major causes of mortality after lung resection.

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.

Postpneumonectomy pulmonary edema: can it be predicted preoperatively?

Postpneumonectomy pulmonary edema (PPE) is a rarely reported form of acute lung injury which occurs in up to 4% of all pneumonectomies. The details of two well-documented cases of PPE are described with special emphasis paid to the preoperative lung functions. Both cases illustrated a striking disparity between preserved spirometric lung function and advanced emphysema as detected by quantitative CT emphysema scores and single-breath diffusion of carbon monoxide measurements. Though retrospective in nature, these results suggest a restricted capillary volume plays a critical role in the development of PPE.

Perioperative anaesthetic considerations for patients undergoing lung transplantation

PURPOSE

Five thousand, two hundred and eight lung transplants were performed worldwide before April, 1996. This review will discuss lung transplantation from an historical perspective, its indications, donor and recipient selection criteria, donor lung preparation, surgical considerations, perioperative anaesthetic management, and associated morbidity and mortality.

SOURCE

Recent literature on perioperative anaesthetic management of lung transplantation and experience from international centres including the Toronto Lung Transplant Group and the St. Louis Lung Transplant Group.

PRINCIPAL FINDINGS

Lung transplantation comprises of a family of operations, including single lung transplant, bilateral single lung transplant, lobar transplant and block heart-lung transplant. Improved donor lung preservation techniques have increased the duration of cold ischaemic time. The advent of bilateral single lung transplant has decreased the requirement for cardiopulmonary bypass, and airway complications have been reduced by adoption of the telescoping bronchial anastomoses. Advances in perioperative monitoring (including transoesophageal echocardiography), pulmonary vasodilators (e.g., nitric oxide and prostaglandin E1), cardiopulmonary bypass and ventilatory management, and a better understanding of the pathophysiological processes during the procedure have improved perioperative anaesthetic management. Also, advances in broad spectrum antibiotics and immunosuppressant drugs have improved the outcome by better management of the complications of infection and rejection.

CONCLUSION

Lung transplantation improves the quality of life with marginal improvement in life expectancy of the recipients. It is an expensive procedure requiring continued resources for long term management of these patients.

[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.

Hyperinflation of canine lung allografts during storage increases reperfusion pulmonary edema

The optimal state of inflation for lung allografts during preservation is not known. We previously showed that hyperinflation of canine lung allografts during storage improved posttransplant graft function as measured during 10 minutes of contralateral pulmonary artery occlusion. However, we have also shown that hyperinflation during storage increases pulmonary capillary permeability. It is possible that short-term total cardiac perfusion through the transplanted left lung (for assessment) may not adequately reproduce the clinical situation. The purpose of this study was to assess the effects of hyperinflation during storage in a canine left single-lung transplantation model in which all perfusion was continuously directed to the graft after implantation. Twenty canine left single-lung transplants were done. The lungs of donor animals were ventilated at a tidal volume of 750 ml and an inspired oxygen fraction of 100%. Donor lungs were flushed with modified Euro-Collins solution and the trachea occluded at end inspiration. For donors in groups I and III, the trachea was sealed at that postinflation volume. In groups II and IV, 200 cc of air was withdrawn from the endotracheal tube under positive pressure and the trachea sealed at the lower tidal volume. Lungs were then extracted and stored at 1 degree C for 12 hours. After the preservation period, left lung transplants were performed. After implantation in all groups, the right pulmonary artery was ligated. In groups I and II, the right bronchus was ligated and in groups III and IV the right bronchus was kept open. Subsequent allograft gas exchange and hemodynamics were assessed during a 6-hour period of reperfusion. After assessment, both lungs were excised, wet/dry lung weight ratio was calculated, and histologic examination was done. During the 6-hour assessment, lungs stored in a state of hyperinflation (groups I and III) showed rapid deterioration of gas exchange. At the final assessment, arterial oxygen tension and alveolar-arterial oxygen gradient of groups I and III were significantly worse than those of groups II and IV (group I versus group II: arterial oxygen tension 87.5 +/- 15.0 versus 373.8 +/- 65.5 mm Hg, alveolar-arterial oxygen gradient 564.4 +/- 13.2 versus 298.6 +/- 69.3 mm Hg, p < 0.05; group III versus group IV: arterial oxygen tension 245.4 +/- 33.0 versus 543.6 +/- 41.8 mm Hg, alveolar-arterial oxygen gradient 392.5 +/- 35.6 versus 120.5 +/- 34.7 mm Hg, p < 0.01). We conclude that donor lung hyperinflation during storage does not provide better posttransplant allograft function when perfusion is limited only to the allograft.

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.

Pressure gradient across the pulmonary artery anastomosis during lung transplantation

BACKGROUND

Perioperative monitoring of pulmonary artery (PA) pressures in lung transplant recipients is critical. This report characterizes an intraoperative gradient across the PA anastomosis in a series of patients undergoing bilateral sequential lung transplantation.

METHODS

Hemodynamic measurements were obtained in a series of 10 patients before anesthetic induction, during one-lung ventilation/perfusion of the newly transplanted first lung with the PA catheter proximal and distal to the anastomosis and after arrival in the intensive care unit. The following measurements were recorded: central venous pressure, cardiac output, PA occlusion pressure, and systemic and pulmonary arterial pressures (systolic, diastolic, mean).

RESULTS

Although a systolic pressure gradient of more than 10 mm Hg across the anastomosis was observed in all patients, there was a significant variation in systolic (13 to 59 mm Hg), diastolic (2 to 10 mm Hg), and mean (5 to 27 mm Hg) PA gradients. Mean proximal systolic PA pressure measurements (56.2 +/- 20.6 mm Hg) were greater when compared to measurements obtained distal to the anastomosis (28.6 +/- 10.1 mm Hg, p = 0.001) and to those obtained in the postoperative period (32.1 +/- 9.7 mm Hg, p = 0.004).

CONCLUSIONS

The present study demonstrates that during single-lung ventilation and perfusion, the PA pressure measured proximally may not reflect accurately the pressure distal to the vascular anastomosis.

Administration of prostaglandin E1 after lung transplantation improves early graft function

Early graft dysfunction continues to be a major clinical problem after lung transplantation. The objective of this experiment was to determine whether continuous administration of prostaglandin E1 (PGE1) after lung transplantation has a beneficial effect on early graft function. Left lung allotransplantation was performed in 10 size-matched mongrel dogs (weight, 24.4 to 31.4 kg). Lung preservation consisted of a bolus injection of PGE1 (250 micrograms) into the pulmonary artery, followed by a pulmonary artery flush with 50 mL/kg of 4 degrees C modified Euro-Collins solution. The lungs were then stored at 1 degree C for 12 hours. Left lung transplantation was performed using standard technique. The right pulmonary artery and right bronchus were ligated prior to chest closure. Animals were placed in the supine position and ventilated for 6 hours with 100% oxygen at a rate of 20 breaths/min, a tidal volume of 550 mL, and a positive end-expiratory pressure of 5 cm H2O. Animals were randomly allocated to one of two groups. Group I animals (n = 6) received continuous PGE1 infusion from the onset of implantation. The dose was gradually increased and fixed when mean systemic pressure showed a 10% decrease (mean PGE1 dose, 31.7 +/- 6.9 ng.kg-1.min-1). Group II animals (n = 4) received no PGE1. After the 6-hour assessment period, arterial oxygen tension and alveolar-arterial oxygen pressure difference were preserved in group I compared with group II (group I versus group II: arterial oxygen tension, 255.8 +/- 37.6 mm Hg versus 64.7 +/- 7.9 mm Hg [p < 0.05]; alveolar-arterial oxygen pressure difference, 411.1 +/- 70.5 mm Hg versus 597.5 +/- 1.3 mm Hg [p < 0.05]).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Pulmonary arterial wedge pressure measurement can modify pulmonary haemodynamics in patients with chronic lung disease

In 20 patients with chronic lung disease in stable condition, haemodynamic values were compared during wedging of a Swan-Ganz catheter, either in a distal branch of the pulmonary artery, or by balloon inflation (with 1 ml) in a proximal branch, mostly excluding right lower lobe perfusion. Average pulmonary arterial wedge pressure, systemic arterial pressure, transcutaneous and mixed venous oxygen saturation, cardiac output and pulmonary blood volume (PBV) were not statistically different during distal and proximal wedging, but systolic pulmonary arterial pressure and pulmonary vascular resistance were slightly higher during balloon inflation (P < 0.05). In four patients, PBV decreased by 20% or more; cardiac output was reduced and mean systemic arterial pressure diminished by 10 mmHg or more in three patients. Of the two patients with the lowest PBV, one did not tolerate the balloon inflation because of dyspnoea, and the other showed dramatically haemodynamic changes. These were more likely to occur when the occlusion lead to the exclusion of a still well perfused area. Our results support optimal matching between ventilation and perfusion in patients with chronic lung disease, although both are inhomogeneous. When pulmonary vascular restriction can be suspected, pressure obtained during catheter wedging by balloon inflation should be interpreted with caution. Monitoring arterial oxygen saturation and systemic arterial pressure before and during the manoeuver could help to diagnose haemodynamic effects of the balloon inflation in a proximal pulmonary artery.

Noncardiogenic pulmonary edema complicating lung resection

Postresectional pulmonary edema is a rare but potentially fatal complication of thoracic operations. In a retrospective study of 402 lung resections we have identified 11 cases of postresectional, noncardiogenic pulmonary edema. We have analyzed the individual data to test recognized hypotheses regarding this condition. Pulmonary edema occurred in 5.1% of right pneumonectomies, 4.0% of left pneumonectomies, and 1% of all lobectomies. In 2 patients the symptoms occurred immediately after operation; in the other 9 the mean interval to diagnosis was 43.4 hours. All 11 patients were in a positive fluid balance in the first 24 hours after operation (mean, 20.8 +/- 9.1 mL/kg). However, there was no significant difference between this value and the respective values for control groups of 20 patients having pneumonectomies and 20 patients having lobectomies in whom pulmonary edema did not develop. Our findings differ from other reported series in that perioperative fluid overload was not found to be a significant contributory factor in the development of postresectional pulmonary edema. We discuss other possible mechanisms for this phenomenon.

Hemodynamic effects of lobar pulmonary artery occlusion in a porcine sepsis model

We induced severe pulmonary hypertension and acute lung injury in 6 pigs by Pseudomonas aeruginosa infusion. We studied the effect of pulmonary artery catheter inflation of a pulmonary artery catheter balloon in the left lower lobar pulmonary artery was accompanied by a significant (p less than 0.05, paired t test) increase in pulmonary artery pressure, a decrease in left atrial pressure, a decrease in cardiac output, and a decrease in mean arterial pressure. No significant changes occurred when the catheter was advanced into the wedged position without balloon inflation. Balloon inflation had no significant effect on these variables before bacterial infusion. We conclude that with sufficiently severe pulmonary hypertension in association with diffuse lung injury, lobar pulmonary artery occlusion may cause alterations in cardiac output and left atrial pressure. This may confuse interpretation of pulmonary artery catheter measurements.

Permeability pulmonary edema following lung resection

The etiology of edema associated with pulmonary resection was investigated in five patients during the immediate postoperative period. Three patients received pneumonectomy while two patients had one lobe resected. All patients suffered from severe respiratory distress and had x-ray evidence of diffuse interstitial pulmonary edema within 12 hours of surgery. Hemodynamic data were obtained with radial and pulmonary artery catheters. Edema fluid was obtained along with blood samples for simultaneous determination of protein and albumin content. All patients studied had normal or high cardiac output, normal cardiac filling pressures, and edema fluid protein to serum protein ratio of 0.6 or greater suggestive of permeability changes contributing to edema fluid accumulation. Calculated shunt fraction exceeded 25 percent in all patients. Pulmonary edema has been noted in patients following pulmonary resection in the early postoperative period. In patients reviewed here, two factors appeared to be significant. First is an increase in pulmonary capillary pressure associated with passage of a normal to high cardiac output in a reduced volume pulmonary vascular bed. The second factor, as demonstrated by protein content in the edema fluid, is injury to the alveolar capillary membrane.

Postpneumonectomy pulmonary oedema

The occurrence of pulmonary oedema was studied retrospectively in 243 patients who underwent pneumonectomy in one hospital from 1975 to 1984. Pulmonary oedema developed in eight of 113 patients who had a right sided pneumonectomy and in three of 130 patients undergoing a left sided procedure. It occurred more commonly in patients requiring a second thoracotomy because of blood loss (in three out of seven patients). There were no significant differences preoperatively in pulmonary function, lung perfusion scans, or cardiovascular condition between patients who subsequently developed pulmonary oedema and those who did not. Postoperative fluid balance was significantly more positive in patients developing pulmonary oedema than in those not developing oedema. Thus pulmonary oedema was associated with right sided pneumonectomy, repeat thoracotomy, and more positive fluid balance.

Cardiac dysrhythmia following pneumonectomy. Clinical correlates and prognostic significance

Cardiac tachydysrhythmias occurred in 53 (22 percent) of 236 consecutive patients undergoing pneumonectomy. All patients had preoperative electrocardiograms which showed normal sinus rhythm. Patients did not receive digitalis before surgery. Atrial fibrillation was the most common dysrhythmia (64 percent; 34/53), followed by supraventricular tachycardia (23 percent; 12/53) and atrial flutter (13 percent; 7/53). No episodes of ventricular tachycardia were documented. Elevated concentrations of cardiac enzymes were associated with 12 (28 percent) of 43 tachydysrhythmias. Recurrent or persistent dysrhythmias were documented in 29 (55 percent) of 53 patients despite medical management or electrocardioversion (or both). Thirty-one percent (9/29) of these patients subsequently died during their hospitalization. There was no correlation between standard preoperative pulmonary function tests and the incidence of postoperative dysrhythmia. In addition, there was no correlation of dysrhythmia with postoperative diagnoses, surgical staging for lung cancer, postoperative arterial blood gas levels, or the fact that a completion pneumonectomy or chest wall resection was undertaken. An increased incidence of tachydysrhythmia was noted in patients undergoing intrapericardial dissections and those who developed postoperative interstitial or perihilar pulmonary edema. Twenty-five percent (13) of the patients experiencing tachydysrhythmias died within 30 days following their pneumonectomy. We conclude that tachydysrhythmias after pneumonectomy are associated with significant mortality, have poor correlation to preoperative pulmonary function, and occur more frequently following intrapericardial dissection and in patients who develop postoperative interstitial pulmonary edema or perihilar pulmonary edema.