On the crucial ventilatory setting adjustment from two- to one-lung ventilation

Strategic ventilation reduces non-ventilated contralateral lung injury induced by one-lung ventilation in rabbits

ABSTRACT One lung ventilation (OLV) often results in trauma to the unventilated contralateral lung. This study aims to evaluate the effects of different OLV regimens on the injury of the unventilated contralateral lung to identify the best conditions for OLV. Forty rabbits were divided into five groups: a sham group, OLV group I (fraction of inspired oxygen (FIO2) 1.0, tidal volume (VT) 8mL/kg, respiratory rate (R) 40 breaths/min and inspiratory/expiratory ratio (I:E) 1:2), OLV group II (FIO2=1.0, VT 8mL/kg, R 40 breaths/min, I:E 1:2, and positive end-expiratory pressure (PEEP) 5 cm H2O), OLV group III (FIO2 1.0, VT 6mL/kg, R 40 breaths/min, I:E 1:2 and PEEP 5 cm H2O) and OLV group IV (FIO2 0.8, VT 6mL/kg, R 40 breaths/min, I:E 1:2 and PEEP 5 cm H2O). Animals from all OLV groups received two-lung ventilation (TLV) to establish a baseline, followed by one of the indicated OLV regimens. The rabbits in the sham group were intubated through trachea and ventilated with fresh air. Arterial blood gas samples were collected, lung injury parameters were evaluated, and the concentrations of TNF-α and IL-8 in bronchoalveolar lavage fluid (BALF) and pulmonary surfactant protein A (SPA) in the unventilated lung were also measured. In OLV group I, the unventilated left lung had higher TNF-α, IL-8 and lung injury score but lower SPA than the ventilated right lung. In OLV groups I to III, the concentrations of TNF-α, IL-8 and lung injury score in the left lung decreased but SPA increased. No differences in these parameters between OLV groups III and IV were observed. Strategic ventilation designed for OLV groups III and IV reduced OLV-induced injury of the non-ventilated contralateral lung in rabbits.

Mechanical ventilation management during cardiothoracic surgery: an open challenge

Mechanical ventilation during surgery is a highly complex procedure, particularly in cardiothoracic surgery, where patients need to undergo substantial hemodynamic management, involving large fluid exchanges and pharmacological manipulation of vascular resistance, as well as direct manipulation of the lungs themselves. Cardiothoracic surgery is burdened by a high rate of postoperative pulmonary complication (PPC), comorbidity, and mortality. Recent trials have examined various techniques to preserve lung function, although consensus on best practice has yet to be reached. This might be due to the close relationship between the circulatory and pulmonary systems. The use of a technique designed to prevent pulmonary complication might negatively impact the hemodynamics of an already critical patient. Stress-induced lung injury can occur during surgery for various reasons, some of which have yet to be fully investigated. In cardiac surgery, this damage is mainly ascribed to two events: cardiopulmonary bypass (CPB) and sternotomy. In thoracic surgery, on the other hand, overdistention and permissive hyperoxia, both routinely used on one lung to compensate for the collapse of the other, are generally to blame for lung injury. In recent years "protective" ventilation strategies have been proposed to spare lung parenchyma from stress-induced damage. Despite the growing interest in protective ventilation techniques, there are still no clear international guidelines for mechanical ventilation in cardiothoracic surgery. However, some recent progress has been made, with positive clinical outcomes.

Effect of tidal volume on extravascular lung water content during one-lung ventilation for video-assisted thoracoscopic surgery: a randomised, controlled trial

BACKGROUND

The use of low tidal volume during one-lung ventilation (OLV) has been shown to attenuate the incidence of acute lung injury after thoracic surgery.

OBJECTIVE

To test the effect of tidal volume during OLV for video-assisted thoracoscopic surgery on the extravascular lung water content index (EVLWI).

DESIGN

A randomised, double-blind, controlled study.

SETTING

Single university hospital.

PARTICIPANTS

Thirty-nine patients scheduled for elective video-assisted thoracoscopic surgery.

INTERVENTIONS

Patients were randomly assigned to one of three groups (n = 13 per group) to ventilate the dependent lung with a tidal volume of 4, 6 or 8 ml  kg(-1) predicted body weight with I:E ratio of 1:2.5 and PEEP of 5 cm H2O.

MAIN OUTCOME MEASURES

The primary outcomes were perioperative changes in EVLWI and EVLWI to intrathoracic blood volume index (ITBVI) ratio. Secondary outcomes included haemodynamics, oxygenation indices, incidences of postoperative acute lung injury, atelectasis, pneumonia, morbidity and 30-day mortality.

RESULTS

A tidal volume of 4 compared with 6 and 8 ml  kg(-1) after 45 min of OLV resulted in an EVLWI of 4.1 [95% confidence interval (CI) 3.5 to 4.7] compared with 7.7 (95% CI 6.7 to 8.6) and 8.6 (95% CI 7.5 to 9.7) ml  kg(-1), respectively (P < 0.003). EVLWI/ITBVI ratios were 0.57 (95% CI 0.46 to 0.68) compared with 0.90 (95% CI 0.75 to 1.05) and 1.00 (95% CI 0.80 to 1.21), respectively (P < 0.05). The incidences of postoperative acute lung injury, atelectasis, pneumonia, morbidity, hospitalisation and 30-day mortality were similar in the three groups.

CONCLUSION

The use of a tidal volume of 4 ml kg during OLV was associated with less lung water content than with larger tidal volumes of 6 to 8 ml kg(-1), although no patient developed acute lung injury. Further studies are required to address the usefulness of EVLWI as a marker for the development of postoperative acute lung injury after the use of a low tidal volume during OLV in patients undergoing pulmonary resection.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT01762709.

Effects of tidal volume and PEEP on arterial blood gases and pulmonary mechanics during one-lung ventilation

PURPOSE

The main problem of one-lung ventilation (OLV) is hypoxemia. The use of a high tidal volume for preventing hypoxemia during OLV is controversial. We compared the effects of a high tidal volume versus a low tidal volume with or without PEEP on arterial oxygen tension (PaO(2)) and pulmonary mechanics during OLV.

METHODS

Sixty patients (age range, 16-65 years; ASA I, II) who underwent wedge resection with video-assisted thoracostomy during OLV were assigned to three groups: group I received a high tidal volume (10 ml/kg) (n = 20), group II received a low tidal volume (6 ml/kg) (n = 20), and group III received a low tidal volume (6 ml/kg) with PEEP (5 cmH(2)O) (n = 20). Patient hemodynamics, pulmonary mechanics, and arterial blood gases were measured before (T(0)) OLV and 5 (T(1)), 15 (T(2)), 30 (T(3)), and 45 min (T(4)) after OLV.

RESULTS

The PaO(2)/FiO(2) ratios of group II and III were significantly decreased and the incidence of hypoxemia was significantly higher in groups II and III than in group I (P < 0.05).

CONCLUSION

During OLV, mechanical ventilation with a low tidal volume with or without PEEP increased hypoxemia as compared to that when performing OLV with a high tidal volume.