Left, but not right, one-lung ventilation causes hypoxemia during endoscopic transthoracic sympathectomy

Cerebral oxygen desaturation in patients with totally thoracoscopic ablation for atrial fibrillation: A prospective observational study

BACKGROUND

Epicardial radiofrequency ablation for stand-alone atrial fibrillation under total video-assisted thoracoscopy has gained popularity in recent years. However, severe cardiopulmonary disturbances during the surgery may affect cerebral perfusion and oxygenation. We therefore hypothesized that regional cerebral oxygen saturation (rSO2) would decrease significantly during the surgery. In addition, the influencing factors of rSO2 would be investigated.

METHODS

A total of 60 patients scheduled for selective totally thoracoscopic ablation for stand-alone atrial fibrillation were enrolled in this prospective observational study. The rSO2 was monitored at baseline (T0), 15 min after anesthesia induction (T1), 15 minute after 1-lung ventilation (T2), after right pulmonary vein ablation (T3), after left pulmonary vein ablation (T4) and 15 minute after 2-lung ventilation (T5) using a near-infrared reflectance spectroscopy -based cerebral oximeter. Arterial blood gas was analyzed using an ABL 825 hemoximeter. Associations between rSO2 and hemodynamic or blood gas parameters were determined with univariate and multivariate linear regression analyses.

RESULTS

The rSO2 decreased greatly from baseline 65.4% to 56.5% at T3 (P < .001). Univariate analyses showed that rSO2 correlated significantly with heart rate (r = -0.173, P = .186), mean arterial pressure (MAP, r = 0.306, P = .018), central venous pressure (r = 0.261, P = .044), arterial carbon dioxide tension (r = -0.336, P = .009), arterial oxygen pressure (PaO2, r = 0.522, P < .001), and base excess (BE, r = 0.316, P = .014). Multivariate linear regression analyses further showed that it correlated positively with PaO2 (β = 0.456, P < .001), MAP (β = 0.251, P = .020), and BE (β = 0.332, P = .003).

CONCLUSION

Totally thoracoscopic ablation for atrial fibrillation caused a significant decrease in rSO2. There were positive correlations between rSO2 and PaO2, MAP, and BE.

Is two lung ventilation with artificial pneumothorax a better choice than one lung ventilation in minimally invasive esophagectomy?

Two lung ventilation (TLV) with artificial pneumothorax has been introduced into MIE for several years. A few researches have reported its clinical application, and proved its safety and feasibility. However, it is still controversial whether TLV with artificial pneumothorax is a better choice than one lung ventilation (OLV). Obviously, single lumen endotracheal tube is easy for intubation and intraoperative maintenance. Potential problems during intervention include hemodynamic changes, oxygenation, and air embolism. In this paper, present literature is reviewed about two and one lung ventilation in thoracoscopy, looking for clear conclusions for future application.

A novel method for right one-lung ventilation modeling in rabbits

There is no standard method by which to establish a right one-lung ventilation (OLV) model in rabbits. In the present study, a novel method is proposed to compare with two other methods. After 0.5 h of baseline two-lung ventilation (TLV), 40 rabbits were randomly divided into sham group (TLV for 3 h as a contrast) and three right-OLV groups (right OLV for 3 h with different methods): Deep intubation group, clamp group and blocker group (deeply intubate the self-made bronchial blocker into the left main bronchus, the novel method). These three methods were compared using a number of variables: Circulation by heart rate (HR), mean arterial pressure (MAP); oxygenation by arterial blood gas analysis; airway pressure; lung injury by histopathology; and time, blood loss, success rate of modeling. Following OLV, compared with the sham group, arterial partial pressure of oxygen and arterial hemoglobin oxygen saturation decreased, peak pressure increased and lung injury scores were higher in three OLV groups at 3 h of OLV. All these indexes showed no differences between the three OLV groups. During right-OLV modeling, less time was spent in the blocker group (6±2 min), compared with the other two OLV groups (13±4 min in deep intubation group, P<0.05; 33±9 min in clamp group, P<0.001); more blood loss was observed in clamp group (11.7±2.8 ml), compared with the other two OLV groups (2.3±0.5 ml in deep intubation group, P<0.001; 2.1±0.6 ml in blocker group, P<0.001). The first-time and final success rate of modeling showed no differences among the three OLV groups. Deep intubation of the self-made bronchial blocker into the left main bronchus is an easy, effective and reliable method to establish a right-OLV model in rabbits.

Application of CO2 waveform in the alveolar recruitment maneuvers of hypoxemic patients during one-lung ventilation

Deterioration of gas exchange during one-lung ventilation (OLV) is caused by both total collapse of the nondependent lung and partial collapse of the dependent lung. Alveolar recruitment maneuver improves lung function during general anesthesia. The objective of this study was to investigate whether there is an indirect relationship between the changes of CO2 expirogram and the selective lung recruitment. To further improve the oxygenation and gas exchange, we compare adjust setting of ventilated parameters based on CO2 expirogram and a preset setting of ventilated parameters during OLV in patients undergoing right-side thoracic surgery.Thirty patients met the requirements criteria that were studied at 3 time points: during two-lung ventilation (TLV), during OLV with preset ventilation parameters (OLV-PP), and during OLV with adjustable ventilation parameters (OLV-AP) that are in accordance with CO2 expirogram. Adjustable ventilation parameters such as tidal volume (VT), respiratory rate (RR), positive end-expiratory pressure (PEEP), and the ratio of inspiratory to expiratory were adjusted by utilizing the phase III slopes of CO2 expirogram, which together with the relationship between the changes of CO2 expirogram and the selective lung recruitment.During OLV, the phase III slopes of CO2 expirogram in patients with pulse oxymetry (SpO2) decreased less than 93% after the OLV-PP, and were absolutely different from that during TLV. After OLV-AP, the phase III slopes of CO2 expirogram and SpO2 were similar to those during TLV. During OLV, however, parameters of ventilation setting in both OLV-PP and OLV-AP are obviously different.This study indicates that alveolar recruitment by utilizing CO2 expirogram probably improves SpO2 level during one-lung ventilation.

Elective Thoracoscopic Maze with Venoarterial Extracorporeal Life Support

This case report describes the intraoperative use of extracorporeal life support (ECLS) for an elective thoracoscopic maze procedure in which the patient could not tolerate one-lung ventilation because of hypoxia. Potential pitfalls associated with the anesthetic management of elective intraoperative ECLS include managing native cardiac ejection and ECLS flows to provide optimal oxygenation and cardiac output. Particular attention must be paid to cardiac and respiratory physiology when ECLS is used in a patient with normal cardiac function.

Cardiovascular changes during drainage of pericardial effusion by thoracoscopy

BACKGROUND

Cardiovascular changes during drainage of pericardial effusion are not well understood, and most studies are of systemic effects and not of right ventricular performance. Thoracoscopy is not widely used to drain pericardial effusions because of haemodynamic changes in relation to the use of single lung ventilation.

PATIENTS AND METHODS

We studied 16 patients undergoing partial pericardiectomy for pericardial effusion, using videothoracoscopy with a low-pressure pneumothorax (6 mm Hg). Cardiac output was measured by thermodilution with the patient anaesthetized in the supine position before the procedure; in the right lateral position after a low-pressure pneumothorax had been established; and after drainage of the pericardial effusion.

RESULTS

Before the procedure, cardiac output was low and central venous pressure and pulmonary artery occlusion pressure were increased. Systemic vascular resistance and arterial blood pressure were within normal limits. Cardiac filling pressure and pulmonary arterial pressure increased during the pneumothorax. After the drainage cardiac index increased and systemic and pulmonary vascular resistances were reduced.

CONCLUSIONS

Pericardial effusion reduces right ventricular distensibility, right and left systolic ventricular function, and cardiac output. Anaesthesia with mechanical ventilation and a low-pressure pneumothorax do not affect the circulation greatly. Drainage of the pericardial effusion allows cardiac distensibility to increase and cardiac performance changes to allow increased ejection.

Anaesthesia for thoracoscopic surgery

The surgical requirement for thoracoscopy is a good view of the contents of the thorax. This is achieved by capitalizing on natural consequences and the skills of anaesthesiologists to produce a pneumothorax and collapse the ipsilateral lung--a process that is commonly enhanced by insufflating carbon dioxide. Insufflating CO2 to actively promote lung collapse creates the dynamics of a tension pneumothorax. Complications are clinically insignificant if CO2 is used judiciously. There is a body of experience using ordinary endotracheal tubes and two-lung ventilation. Techniques of one-lung ventilation are more widely reported. All the factors known to contribute to the significant increase in shunt fraction associated with one-lung ventilation apply. The manoeuvre of collapsing a lung is no longer regarded as benign. Chemical attempts to produce a reversible post-pneumonectomy pulmonary circulation have not been shown to be an improvement. Post-operative pain can be severe. The mechanism is not defined but it differs from that associated with thoracotomy. Epidural analgesia and opioids may be required. Chronic pain syndromes have been described as complications.

Gas exchange and pulmonary hemodynamics during lung resection in patients at increased risk: relationship with preoperative exercise testing

STUDY OBJECTIVES

To evaluate the intraoperative evolution of patients with COPD during lung resection and to test whether exercise testing could be helpful in the prediction of the intraoperative course.

DESIGN

Prospective study.

SETTING

University teaching hospital.

PATIENTS

Forty patients (mean [+/- SD] age, 65 +/- 9 years) with COPD (ie, FEV(1), 55 +/- 11% of predicted) and resectable lung neoplasms.

INTERVENTIONS

Preoperatively, pulmonary function testing, quantitative lung perfusion scanning, and exercise performance testing were administered. Intraoperatively, pulmonary, hemodynamic, and blood gas measurements were performed at five stages, including periods of two-lung ventilation (TLV) and periods of one-lung ventilation (OLV).

RESULTS

During OLV, compared with TLV, the PaO(2)/fraction of inspired oxygen (FIO(2)) ratio decreased from 458 +/- 120 to 248 +/- 131 mm Hg (p < 0.05), whereas pulmonary artery pressure (PAP) increased from 18 +/- 5 to 23 +/- 5 mm Hg (p < 0.05). Cardiac output (t) also increased from 4.0 +/- 1.2 to 5.1 +/- 1.9 L/min (p < 0.05), yielding to a higher mixed venous PO(2). Both PaO(2) and t during OLV were significantly lower in patients who had undergone right thoracotomies compared with those who had undergone left thoracotomies. The PaO(2)/FIO(2) ratio during OLV correlated with the PaO(2) during exercise (r = 0.39; p = 0.01) and with the perfusion of the non-neoplastic lung (r = 0.44; p = 0.005).

CONCLUSIONS

In COPD patients, OLV leads to a significant derangement of gas exchange, which is more pronounced in right thoracotomies. Preoperative measurement of PaO(2) during exercise and the distribution of perfusion by lung scan might be useful to identify those patients who are at the greatest risk of abnormal gas exchange during lung resections.

Haemodynamic changes during thoracoscopic surgery the effects of one-lung ventilation compared with carbon dioxide insufflation

We investigated the haemodynamic and respiratory effects of one-lung ventilation and carbon dioxide insufflation in 13 adult patients undergoing video-assisted thoracoscopy. Cardiorespiratory variables were determined during carbon dioxide insufflation at intrahemithoracic pressures of 5, 10 and 15 mmHg, and after 5 and 15 min of one-lung ventilation. Carbon dioxide insufflation was associated with a clear deterioration in circulatory function. The cardiac index decreased subsequent to increasing intrathoracic pressures. The mean cardiac index (SD) at pressures of 10 and 15 mmHg was 1.86 (0.39) and 1.52 (0.46), respectively, and may be compared with the reduced venous return consistent with tension pneumothorax. One-lung ventilation did not affect haemodynamic variables but reduced arterial oxygenation indices (PaO2/FIO2) from 424.29 (160.79) after induction of anaesthesia, to 207.72 (125.50) after 5 min and 172.04 (72.03) after 15 min of one-lung ventilation, respectively. The oxygenation index was not influenced by intrahemithoracic carbon dioxide insufflation. One-lung ventilation via a double-lumen endobronchial tube is safe and convenient for video-assisted thoracoscopic surgery. It has no further consequences on haemodynamic variables, whereas the compression of the lung by carbon dioxide insufflation may cause circulatory dysfunction.

Effects of one-lung ventilation on cardiac autonomic nervous activity as evaluated by power spectral analysis of heart rate variability

The purpose of this prospective study was to evaluate the effects of one-lung ventilation on the activity of the cardiac autonomic nervous system. Ten adult patients who underwent thoracotomy were endotracheally intubated with a double-lumen tube under general anesthesia using isoflurane. After induction of anesthesia, a continuous, 256-sec electrocardiogram (ECG) was obtained during bilateral lung ventilation (control) followed by recordings during one-lung ventilation of each side. Using the R-R interval tachograms obtained for the 256-sec ECGs, low frequency (LF: 0.04-0.15 Hz) and high frequency (HF: 0.15-0.40 Hz) bands of the spectral density of the heart rate variability and the HF/LF ratio were analyzed using the fast Fourier transform algorithm. Log(HF), which indicates parasympathetic activity, increased during one-lung ventilation on each side, but did not differ between ventilated sides. Log(LF), which represents sympathetic and parasympathetic activity, increased similarly to log(HF) on both sides. Log(HF/LF), the balance of the sympathetic and parasympathetic activity, did not change during one-lung ventilation. We suggest that one-lung ventilation alone does not substantially affect the cardiac autonomic nervous system.

Sequential changes of arterial oxygen tension in the supine position during one-lung ventilation

To investigate how surgical positions affect the severity and progress of hypoxemia during one-lung ventilation (OLV), we studied 33 adult patients undergoing right thoracotomy with left OLV. The patients were divided into three groups according to the positions during surgery as follows: the supine position (SP) group (n = 11), the left semilateral decubitus position (LSD) group (n = 9), and the left lateral decubitus position (LLD) group (n = 13). Analysis of arterial blood gases was sequentially determined every 5 min for 30 min during OLV (fractional ratio of inspiratory oxygen = 1.0) in each position. OLV was promptly terminated and switched to bi-lung ventilation if Spo2 declined to 90%. Pao2 progressively decreased with time in all three groups (P < 0.01). The incidence of termination of OLV within 30 min was higher in the SP group (82%), compared with that in the LSD (11%) and LLD (8%) groups (P < 0.01). Final Pao2 (65+/-12 mm Hg, mean +/- SD, P < 0.01 versus LLD, P < 0.05 versus LSD) and SaO2 (91%+/-4%, P < 0.01 versus LLD and LSD) at the termination of OLV in the SP group were the lowest. There was no difference between these values in the LSD and LLD groups (128+/-54 mm Hg, 96%+/-2%, and 167+/-69 mm Hg, 97%+/-4%, respectively) 30 min after the start of OLV. The time for Pao2 to decrease to 200 mm Hg calculated from each regression curve was 354 s in the SP group, 583 s in the LSD group, and 798 s in the LLD group. The time for Pao2 to decline to 100 mm Hg was 794 s in the SP group. In the regression curves of the LSD and LLD groups, the Pao2 did not decrease to 100 mm Hg. Heart rate was slow at baseline in the SP group (P < 0.05 versus LSD), but other hemodynamic variables did not differ among the three groups throughout this study. The LSD was as effective as the LLD in avoiding life-threatening hypoxemia during OLV.

IMPLICATIONS

Close observation and prompt counteractions including termination of one-lung ventilation (OLV) are crucial for patients under OLV in the supine position, because life-threatening hypoxemia frequently occurs approximately 10 min after starting OLV, even under 100% oxygen inhalation. The left semilateral decubitus position was as effective as the left lateral decubitus position in avoiding life-threatening hypoxemia during OLV.

Near-sitting position and two-lung ventilation for endoscopic transthoracic sympathectomy

OBJECTIVE

To control for hypoxemia during endoscopic transthoracic sympathectomy, usually by using double-lumen tube and one-lung ventilation, a different anesthetic technique was adopted.

DESIGN

A prospective clinical study.

SETTING

A university-affiliated medical center.

PARTICIPANTS

Twenty-one adult patients (10 male and 11 female) between 15 and 44 years of age (mean, 22 years), ASA (American Society of Anesthesiologists) physical status I and II, participated in the study.

INTERVENTIONS

Under general anesthesia, a single-lumen endotracheal tube was inserted. The radial artery was cannulated for blood pressure monitoring and blood gas sampling. Patients were gradually raised from a supine position to 60 to 70 degrees from the horizontal plane. Mean fractional inspiratory O2 ratio was 0.4 +/- 0.02 (mixture of O2 and air) throughout the operation. Blood gas samples were taken during two-lung ventilation before surgery, at each one-chest operation, and when switching between the operated chest sides. An artificial pneumothorax was established by insufflation of CO2, the sympathetic chain coagulated, the pneumothorax released, and the lung reinflated.

MEASUREMENTS AND MAIN RESULTS

Comparisons were performed using one-way analysis of variance and the Bonferroni post-test. Arterial O2 partial pressure at right- and left-chest operation were 209 +/- 83 and 189 +/- 63 mmHg, respectively, compared with 227 +/- 43 and 241 +/- 69 mmHg on two-lung ventilation before and during surgery, respectively. O2 saturation, arterial CO2 partial pressure, bicarbonate, base excess, peak inspiratory pressure, and hemodynamic parameters (in most patients) did not change throughout the operation.

CONCLUSIONS

The near-sitting position, a single-lumen tube, and a continuous two-lung ventilation technique is simple and may prevent hypoxemia during endoscopic transthoracic sympathectomy.