Differential lung ventilation for increased oxygenation during one lung ventilation for video assisted lung surgery

Analysis of risk factors for hypoxemia in PACU for patients undergoing thoracoscopic lung cancer resection based on logistic regression model

OBJECTIVE

This study aims to identify risk factors of hypoxemia in patients undergoin thoracoscopic lung surgery during their stay in the post-anesthesia care unit (PACU). Hypoxemia was defined as any instance of SpO₂ ≤90% lasting for more than one minute during the PACU stay.

METHODS

We conducted a prospective research involving 398 patients who underwent elective thoracoscopic lung surgery in West China Hospital, Sichuan University, from April to July 2024. Patients were classified into hypoxemia and non-hypoxemia groups based on the presence of hypoxemia in the PACU. We compared clinical data between the two groups to identify factors influencing hypoxemia. Variables with statistical significance (P < 0.05) in univariate analysis were included in logistic regression to identify independent risk factors for hypoxemia.

RESULTS

Among the 398 patients studied, 149 (37.4%) experienced hypoxemia. Univariate analysis indicated significant differences in age, BMI, height, ASA classification, hypertension, diabetes, lung function test with Forced Expiratory Volume at 1 s / Forced Vital Capacity (FEV1/FVC), and awakening time between the groups. Logistic regression revealed that age, BMI, ASA classification, hypertension, diabetes, and awakening time were independent risk factors for hypoxemia during anesthesia recovery, while preoperative SpO2 upon entering operating room (OR = 0.882, 95% CI: 0.783-0.993, P = 0.038) was identified as a protective factor.

CONCLUSION

Age, BMI, ASA classification, and preoperative conditions such as hypertension and diabetes are found to contribute to an increased incidence of hypoxemia in PACU following thoracoscopic lung surgery. Emphasizing preoperative lung function assessments and enhanced monitoring may also facilitate timely interventions, thereby improving post-anesthesia recovery and patient outcomes.

Comparison of Ventilation Strategies Across the Perioperative Period in Patients Undergoing General Anesthesia: A Narrative Review

General anesthesia is a critical component of surgical procedures, requiring effective ventilation strategies to ensure adequate oxygenation and prevent complications. This narrative review aims to compare various ventilation techniques used during general anesthesia, focusing on their physiological foundations, clinical applications, and outcomes. Traditional methods, such as high tidal volume ventilation, have evolved into more sophisticated approaches, including protective lung ventilation, which are particularly beneficial for high-risk patients with respiratory comorbidities. The review highlights that protective lung ventilation, characterized by lower tidal volumes and optimal positive end-expiratory pressure, is associated with improved oxygenation, reduced incidence of post-operative pulmonary complications, and enhanced overall recovery. Despite the advantages of personalized ventilation approaches, current evidence remains limited by small sample sizes and variability in study designs. This underscores the need for larger, randomized controlled trials to establish definitive guidelines. Future research should also explore emerging technologies to optimize the real-time management of ventilation parameters. The findings emphasize the importance of individualized ventilation strategies in clinical practice to improve patient outcomes and inform policy development. By advancing our understanding of ventilation techniques, this review aims to contribute to safer anesthesia practices and enhance recovery in surgical patients.

Continuous Positive Airway Pressure versus Differential Lung Ventilation during One Lung Ventilation for Thoracic Surgery

INTRODUCTION

One lung ventilation (OLV) is a technique used during lung resection surgery to facilitate optimal surgical conditions. However, this may result in severe hypoxemia due to the right-to-left shunt created in the collapsed lung. Several techniques are used to overcome hypoxemia, one of which is continuous positive airway pressure (CPAP) to the non-dependent lung. Another technique is ventilating the non-dependent lung with a minimal volume, thus creating differential lung ventilation (DLV) or split lung ventilation (SLV). In this study, we compared the efficacy of CPAP to DLV during video-assisted thoracoscopic (VATS) lung resection.

MATERIALS AND METHODS

In this single-center randomized controlled, cross-over study, each patient acted as his control as well as the study. Patients crossed over from SLV to CPAP (or vice versa) with an interval period during which only OLV was used (control period). The primary objective of the study was to observe the changes in oxygenation, ventilation, and the surgeons' perception of the surgical field using CPAP or SLV to the non-ventilated lung during the period of OLV in patients undergoing thoracic surgery.

RESULTS

The study revealed that oxygenation was significantly better when using SLV to the non-ventilated lung during the period of OLV (P = 0.03). However, the surgeon found a significantly better surgical field when applying CPAP to the surgical field.

CONCLUSIONS

The study showed that using SLV to the non-ventilated lung during the period of OLV was superior in terms of oxygenation, although it interfered more with the surgical field.

Continuous positive airway pressure combined with small-tidal-volume ventilation on arterial oxygenation and pulmonary shunt during one-lung ventilation in patients undergoing video-assisted thoracoscopic lobectomy: A randomized, controlled study

BACKGROUND

One-lung ventilation (OLV) is frequently applied during video-assisted thoracoscopic surgery (VATS) airway management to collapse and isolate the nondependent lung (NL). OLV can give rise to hypoxemia as a result of the pulmonary shunting produced. Our study aimed to assess the influence of continuous positive airway pressure (CPAP) combined with small-tidal-volume ventilation on improving arterial oxygenation and decreasing pulmonary shunt rate (QS/QT) without compromising surgical field exposure during OLV.

METHODS

Forty-eight patients undergoing scheduled VATS lobectomy were enrolled in this research and allocated into three groups at random: C group (conventional ventilation, no NL ventilation intervention was performed), LP group (NL was ventilated with lower CPAP [2 cmH2O] and a 40-60 mL tidal volume [TV]), and HP group (NL was ventilated with higher CPAP [5 cmH2O] and a 60-80 mL TV). Record the blood gas analysis data and calculate the QS/QT at the following time: at the beginning of the OLV (T0), 30 min after OLV (T1), and 60 min after OLV (T2). Surgeons blinded to ventilation techniques were invited to evaluate the surgical fields.

RESULTS

The demography data of the three groups were consistent with the surgical data. At T1, PaO2 in the HP group was substantially higher compared to the C group (P < 0.05), while there was no significant difference in the LP group (P > 0.05). At T1-T2, PaCO2 in the LP and HP groups was significantly less than that in the C group (P < 0.05). At T1, the QS/QT values of groups C, LP, and HP were 29.54 ± 6.89%, 22.66 ± 2.08%, and 19.64 ± 5.76%, respectively, and the QS/QT values in the LP and HP groups markedly reduced (P < 0.01). The surgical field's evaluation by the surgeon among the three groups was not notable (P > 0.05).

CONCLUSION

CPAP combined with small-tidal-volume ventilation effectively improved arterial oxygenation and reduced QS/QT and PaCO2 without compromising surgical field exposure during OLV. Among them, 5 cmH2O CPAP + 60-80 ml TV ventilation had a better effect on improving oxygenation.

Roles of electrical impedance tomography in lung transplantation

Lung transplantation is the preferred treatment method for patients with end-stage pulmonary disease. However, several factors hinder the progress of lung transplantation, including donor shortages, candidate selection, and various postoperative complications. Electrical impedance tomography (EIT) is a functional imaging tool that can be used to evaluate pulmonary ventilation and perfusion at the bedside. Among patients after lung transplantation, monitoring the graft’s pulmonary function is one of the most concerning issues. The feasible application of EIT in lung transplantation has been reported over the past few years, and this technique has gained increasing interest from multidisciplinary researchers. Nevertheless, physicians still lack knowledge concerning the potential applications of EIT in lung transplantation. We present an updated review of EIT in lung transplantation donors and recipients over the past few years, and discuss the potential use of ventilation- and perfusion-monitoring-based EIT in lung transplantation.

Application of Continuous Positive Airway Pressure During Video-Assisted Thoracoscopic Surgery

Purpose of Review

Video-assisted thoracoscopic surgery (VATS) and robotic-assisted thoracoscopic surgery (RATS) are used for anatomic resection of early stage cancer. These surgical techniques require the use of one-lung ventilation (OLV). During OLV, an obligatory intrapulmonary shunt may produce hypoxemia. One method to correct hypoxemia is with the use of continuous positive airway pressure (CPAP). This review focuses on 1) the lung physiology of OLV; 2) application of CPAP in VATS or RATS during supine and lateral position; and 3) the application of CPAP in COVID-19 patients during OLV.

Recent Findings

Studies have shown the beneficial effects of CPAP to improve oxygenation during OLV while the patient is in the lateral decubitus position. In contrast, studies have shown no benefit on improving oxygenation with CPAP in patients undergoing OLV in supine position.

Summary

The application of CPAP to the non-dependent lung is one of the options to treat hypoxemia during VATS or RATS.

Effects of bronchial blockers on gas exchange in infants with one-lung ventilation: a single-institutional experience of 22 cases

BACKGROUND

One-lung ventilation (OLV) in infants is a commonly used airway technique during thoracic surgery. Current research has primarily focused on the operation of the airways and the occurrence of complications. However, there has been minimal data on the pulmonary gas exchange in infants before and after OLV. This study aimed to assess the efficacy of bronchial blockers (BBs) on the pulmonary gas exchange in infants with OLV.

METHODS

A total of 22 infants requiring OLV from January 2017 to August 2019 were included in this study. OLV was achieved by placing BBs outside the endotracheal tube, and all surgeries were performed by the same experienced anesthesiologist. Numerous clinical features, including the oxygenation index (OI), alveolar-arterial oxygen tension gradient (P_A-aO₂), pulmonary dynamic compliance (Cdyn), OLV time, pulmonary collapse time, degree of pulmonary collapse at the operative side, operative time, and immediate hemodynamic indexes before and after intubation were assessed. Data from the arterial blood gases and the ventilator's parameters were obtained at three time points: 15 minutes before OLV (pre-OLV), 15 minutes after the initiation of OLV (during OLV), and 15 minutes after the termination of OLV (post-OLV).

RESULTS

For all patients, the pulmonary gas exchange during OLV was significantly different from both pre-OLV and post-OLV. However, no significant changes of pulmonary function were observed before and after OLV. Extended OLV time was associated with decreased OI and Cdyn, and increased P_A-aO₂ gradient (P<0.001). In addition, no significant changes of hemodynamic indexes before and after intubation were detected. The degree of lung collapse on the operational side during OLV was optimal.

CONCLUSIONS

In this study, the efficacy of BBs on the pulmonary gas exchange in infants with OLV was assessed. The results suggested that although each parameter of pulmonary function pre-OLV were similar to those of post-OLV, an extended period of OLV may lead to compromised lung function.

Intraoperative Anesthetic Management of the Thoracic Patient

The intraoperative anesthetic management for thoracic surgery can impact a patient's postoperative course, especially in patients with significant lung disease. One-lung ventilation poses an inherent risk to patients, including hypoxemia, acute lung injury, and right ventricular dysfunction. Patient-specific ventilator management strategies during one-lung ventilation can reduce postoperative morbidity.