Oxygen toxicity during one-lung ventilation: is it time to re-evaluate our practice?

Perioperative outcomes of non-intubated versus intubated video-assisted thoracoscopic surgery in different thoracic procedures: a propensity score-matched analysis

Background

Non-intubated video-assisted thoracoscopic surgery (NIVATS) is increasingly performed in different types of thoracic procedures. Based on the anesthetic perspective, the outcomes of this method are limited. General anesthesia with intubation and controlled ventilation for video-assisted thoracoscopic surgery (IVATS) is a standard technique. The current study aimed to compare the pulmonary gas exchange between NIVATS and IVATS, with a focus on desaturation event.

Methods

This was a retrospective study conducted at Vajira Hospital. Data were collected from the hospital medical record database between January 9, 2019, and May 15, 2020. A propensity score-matched analysis was used to adjust the confounders by indications and contraindication between NIVATS and IVATS. The perioperative outcomes of VATS and NIVATS were compared by the regression analysis method.

Results

In total, 180 patients were included in the analysis. There were 98 and 82 patients in the NIVATS and IVATS groups, respectively. After a propensity score matching, the number of patients with similar characteristics decreased to 52 per group. None of the patients in both groups experienced desaturation. The lowest oxygen saturation of the NIVATS and IVATS groups did not significantly differ (96.5% vs. 99%, respectively; p = 0.185). The NIVATS group had a significantly higher ETCO2 peak than the IVATS group (43 vs. 36 mmHg, respectively; p < 0.001). According to the regression analysis, the NIVATS group had a significantly shorter anesthetic induction time (Mean difference (MD) = -5.135 min (95% CI = (- 8.878)- (-1.391)) and lower volume of blood loss (MD = -75.565 ml (95%CI = (- 131.08)—(- 20.65) but a higher intraoperative ETCO2 than the IVATS group (MD = 4.561 mmHg (95%CI = 1.852—7.269). Four patients in the NIVATS group required conversion to intubation due to difficulties encountered when using the surgical technique (7.7%, p = 0.041). Seven patients in the IVATS group, but none in the NIVATS group, presented with sore throat (13.5% vs. 0%, respectively; p = 0.006). Moreover, none of the patients in both groups experienced postoperative pneumonia, underwent reoperation, or died.

Conclusions

The anesthetic and surgical outcomes of NIVATS were comparable to those of IVATS.

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.

Perioperative fluid management for pulmonary resection surgery and esophagectomy

Perioperative fluid management is of significant importance during pulmonary resection surgery and esophagectomy. Excessive fluid administration has been consistently shown as a risk factor for lung injury after thoracic procedures. Probable causes of this serious complication include fluid overload, lung lymphatics and pulmonary endothelial damage. Along with new insights regarding the Starling equation and the absence of a third space, current evidence supports a restrictive fluid regimen for patients undergoing pulmonary resection surgery and esophagectomy. Multiple minimally invasive hemodyamic monitoring devices, including pulse pressure/stroke volume variation, esophageal Doppler, and extravascular lung water measurement, were evaluated for optimizing perioperative fluid therapy. Further research regarding the prevention, diagnosis, and treatment of acute lung injury after pulmonary resection and esophagectomy is required.

Anesthesia for thoracic surgery: a survey of middle eastern practice

Purpose:

The main objective of this survey is to describe the current practice of thoracic anesthesia in the Middle Eastern (ME) region.

Methods:

A prospective online survey. An invitation to participate was e-mailed to all members of the ME thoracic-anaesthesia group. A total of 58 members participated in the survey from 19 institutions in the Middle East. Questions concerned ventilation strategies during one-lung ventilation (OLV), anesthesia regimen, mode of postoperative analgesia, use of lung isolation techniques, and use of i.v. fluids.

Results:

Volume-controlled ventilation was favored over pressure-controlled ventilation (62% vs 38% of respondents, P<0.05); 43% report the routine use of positive end-expiratory pressure. One hundred percent of respondents report using double-lumen tube (DLT) as a first choice airway to establish OLV. Nearly a third of respondents, 31.1%, report never using bronchial blocker (BB) in their thoracic anesthesia practice. Failure to pass a DLT and difficult airway are the most commonly cited indications for BB use. Regarding postoperative analgesia, the majority 61.8% favor thoracic epidural analgesia over other techniques (P<0.05).

Conclusions:

Our survey provides a contemporary snapshot of the ME thoracic anesthetic practice.

Mini-ventilation for improved oxygenation during lung resection surgery

Lung separation is frequently used during lung resection to facilitate surgery and hypoxaemia may occur because of increasing pulmonary shunt. In this study, we tested a method of mini-ventilation to the non-dependent lung and compared it to continuous positive airway pressure (CPAP) to improve oxygenation during lung resection. Thirty-eight adult patients participated in this randomised, single-blinded crossover study. Following lung separation, mini-ventilation and CPAP of 5 cmH2O were alternately applied every 15 minutes to the non-dependent lung. Mini-ventilation was performed by a portable time-cycled ventilator with a respiratory rate of 8 breaths/minute and a tidal volume of 0.1 to 0.15 l. Arterial blood gases, peak inspiratory pressure, the dynamic compliance in the dependent lung and the surgeon's evaluation of the surgical field exposure were recorded. The arterial oxygen partial pressure was significantly higher during mini-ventilation compared to CPAP (379 vs 228 mmHg). No difference was noted in the dependent lung peak inspiratory pressure or in the dynamic compliance. The surgical conditions were similar with both methods in 53% of the patients, while the surgeon preferred CPAP in 44% and mini-ventilation in 3%. In conclusion, mini-ventilation is a simple method which improves oxygenation during lung resection. However due to interference with surgical field exposure, it should be reserved for cases in which CPAP does not relieve hypoxaemia.