Aerosolized beta-adrenergic agonist therapy reduces pulmonary edema following lung surgery

Balanced Chest Drainage Prevents Post-Pneumonectomy Pulmonary Oedema

BACKGROUND

Pneumonectomy in the adult patient is associated with a mortality of 1-9%. Death is often due to post pneumonectomy pulmonary oedema (PPPO). The use of balanced chest drainage system (BCD) in the setting of post pneumonectomy has been reported to be of benefit in the prevention of PPPO. This study seeks to compare the incidence of PPPO in patients who underwent pneumonectomy and whose empty pleural space was managed either with CRD or BCD.

METHODS

This retrospective observational cohort study involved 98 patients who were operated on by one surgeon at Liverpool Hospital, Sydney, Australia from 1997 to 2019. The patients were divided into two groups according to the era in which they had their pneumonectomy. Group 1 consisted of 18 patients managed with clamp-release drainage between 1997 and 2002. Group 2 consisted of 80 patients managed with balanced chest drainage between 2003 and 2019. The primary outcomes of interest were the development of PPPO and death. Demographic and clinico-pathological variables between the groups were compared including whether the phrenic nerve was sacrificed, volume of infused intraoperative fluid, duration of single lung ventilation, intraoperative tidal volumes, agents of anaesthetic induction and maintenance, mean urine output in the first 4 postoperative hours, institution of a postoperative 1.5 L fluid restriction, total chest drainage, day of chest drain removal, presence of radiological postoperative mediastinal shift, post-pneumonectomy pulmonary oedema and death. Group characteristics were compared using t-test and chi-squared for continuous and categorical variables respectively. Univariate and multivariate analysis was also undertaken using the Firth method of logistic regression for rare occurrences in a stepwise fashion.

RESULTS

Through univariate analysis, balanced chest drainage, postoperative fluid restriction and intraoperative fluid infusion showed significant effect on PPPO. Through multivariate analysis, balanced chest drainage was found to have independent protective value for PPPO and mortality.

CONCLUSION

Compared with clamp-release drainage, balanced chest drainage results in a lower incidence of post-pneumonectomy pulmonary oedema and death.

Surfactant therapy for acute lung injury and acute respiratory distress syndrome

This article examines exogenous lung surfactant replacement therapy and its usefulness in mitigating clinical acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS). Surfactant therapy is beneficial in term infants with pneumonia and meconium aspiration lung injury, and in children up to age 21 years with direct pulmonary forms of ALI/ARDS. However, extension of exogenous surfactant therapy to adults with respiratory failure and clinical ALI/ARDS remains a challenge. This article reviews clinical studies of surfactant therapy in pediatric and adult patients with ALI/ARDS, focusing on its potential advantages in patients with direct pulmonary forms of these syndromes.

Role of endothelin-1 in acute lung injury

The alveolar-capillary membrane serves as a barrier that prevents the accumulation of fluid in the alveolar space and restricts the diffusion of large solutes while facilitating an efficient gas exchange. When this barrier becomes dysfunctional, patients develop acute lung injury (ALI), which is characterized by pulmonary edema and increased lung inflammation that leads to a life-threatening impairment of gas exchange. In addition to the increase of inflammatory cytokines, plasma levels of endothelin-1 (ET-1), which is a primarily endothelium-derived vasoconstrictor, are increased in patients with ALI. As patients recover, ET-1 levels decrease, which suggests that ET-1 may not only be a marker of endothelial dysfunction but may have a role in the pathogenesis of ALI. While pulmonary edema accumulates, alveolar fluid clearance (AFC) is of critical importance, as failure to return to normal clearance is associated with poor prognosis in patients with pulmonary edema. AFC involves active transport mechanisms where sodium (Na(+)) is actively transported from the alveolar airspaces, across the alveolar epithelium, and into the pulmonary circulation, which creates an osmotic gradient that is responsible for the clearance of lung edema. In this article, we review the relevance of ET-1 in the development of ALI, not only as a vasoconstrictor molecule but also by inhibiting AFC via the activation of endothelial ET-B receptors and generation. Furthermore, this review highlights the therapeutic role of drugs such as beta-adrenergic agonists and, in particular, of endothelin receptor antagonists in patients with ALI.