Periods Of One-lung Ventilation Research Articles

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

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. 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. 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. 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.

Abstract No. : ABS2870: Continuous positive airway pressure versus differential lung ventilation during one lung ventilation for thoracic surgery

Background & Aims:The primary objective of the study was to observe the changes in oxygenation, ventilation and the surgeons’ perception of the surgical field using continuouspositive airway pressure (CPAP) or single lung ventilation (SLV) to the non-ventilated lung during the period of one lung ventilation (OLV) in patients undergoing thoracic surgery.Methods:In this single centre study, each patient acted as his own control as well as the two study groups. Patient were crossed over from SLV to CPAP or vice versa with an interval period during which only OLV was used (control period).Results:The study revealed that oxygenation was significantly better while using SLV to the non-ventilated lung during the period of OLV. However, the surgeon found significantly better surgical field when CPAP was applied.Conclusion: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.GroupPharmacotherapy other than Mg P No n (%)Yes n (%)Group M49 (98.0)1 (2.0)0.031Group C42 (84.0)8 (16.0)

This Month in Anesthesiology

This Month in Anesthesiology

The effect of recruitment maneuver on the development of expansion defect and atelectasis after lobectomy: A double-blind randomized controlled trial

Background/Aim: In pulmonary lobectomy operations, the operation is performed with one-lung ventilation by collapsing the related lung. Postoperative expansion failure on the deflated side is a critical issue. We aimed to correct the expansion failure and atelectasis with the recruitment maneuver performed at the end of the operation. Methods: A total of 61 cases who underwent elective lobectomy under one-lung ventilation were included in this double-blind and prospective study. They were randomized into two groups comprising thirty and thirty-one cases. The first group included patients in whom the cycling recruitment maneuver (cRM) was performed, and the second group comprised patients who underwent the manual recruitment maneuver. Both groups were ventilated similarly during the one-lung ventilation period. After switching to double-lung ventilation, a standardized cycling recruitment maneuver was performed in the first group, and a high-volume manual recruitment maneuver with an anesthetic reservoir bag was used in the second group. Preoperative and postoperative inspiratory and hemodynamic parameters, wakefulness level, pain scores, developments of complications and durations of the hospitalization were noted. Expansion failure and atelectasis were evaluated both with chest radiography and thorax computerized tomography. Results: There was no statistically significant difference among the two groups in terms of age, smoking, duration of operation, preoperative forced expiratory volume in 1 second (FEV1), SpO2 levels, respiratory and hemodynamic parameters noted during the operation, invasive arterial pressure monitoring results, electrocardiogram (ECG) findings, modified Aldrete score (MAS), and visual analogue scores (VAS) (P>0.05 for all). The gender distribution and types of operations performed were also similar. No complications were observed. Expansion failure was seen in 23.3% and 48.8% (P=0.042) of the patients in the cRM and mRM groups, respectively. Additional procedures were needed in 4 patients (13.3%) in the cRM group and in 11 patients (35.5%) in the mRM group. The duration of hospital stay was significantly shorter in the cRM group (P=0.045). Regression analysis revealed a 3.08-times increase in the incidence of expansion failure in the mRM group compared to group cRM. Conclusion: In pulmonary lobectomy operations, we observed that with the utilization of the recruitment maneuver which is performed after switching to double-lung ventilation, the rate of expansion failure, the need for additional procedures and duration of hospital stay decreased.

Spontaneous ventilation combined with double-lumen tube intubation in thoracic surgery

We present the combination of spontaneous ventilation and double-lumen tube intubation in thoracic surgery. At the beginning of the procedures, the patients with a body mass index of ≤ 30 were relaxed for a short time, and a double-lumen tube was inserted. After the utility incision or thoracotomy, the vagus nerve was blocked (in right side in the upper mediastinum; in left side in the aorto-pulmonary window) with 3-5ml of 0.5% bupivacaine. The patients had a bispectral index of 40-60. After the short relaxation period, the patients were ventilating spontaneously without any cough during the manipulation. Between March 10 and September 18. 2020, 26 spontaneous ventilation combined with intubation surgeries were performed: 19 uniportal video-assisted thoracic surgery (15 lobectomies, 1 segmentectomy, and 3 wedge resections) and 7 open (5 lobectomies and 1 sleeve segmentectomy, 1 wedge resection). The mean mechanical and spontaneous one-lung ventilation time was 25.5 (15-115) and 73.3 (45-100) minutes, respectively. In 2 cases conversion to relaxation were necessary (2/26; 7.7%). The mean maximal carbon dioxide pressure was 52.3 (38-66) Hgmm and the mean lowest oxygen saturation was 93.8 (86-99) %. Breathing frequency ranged between 10-25/minute. The mean surgical times was 83.3 (55-130) minutes. Spontaneous ventilation combined with intubation in video-assisted thoracic surgery or open resections is a safe method in selected patients. It can reduce the mechanical one-lung ventilation period with 76.6% and give safe airway for spontaneous ventilation thoracic procedures.

Anesthesia for robotic thoracic surgery.

The management of the robotic thoracic surgical patient requires the knowledge of minimally invasive surgery techniques involving the chest. Over the past decade, robotic-assisted thoracic surgery has grown, and, in the future, it will take an important place in the treatment of complex thoracic pathologies. The enhanced dexterity and three-dimensional visualization make it possible to do this in the small space of the thoracic cavity. Familiarity with the robotic surgical system by the anesthesiologists is mandatory. Management of a long period of one-lung ventilation with a left-sided double-lumen endotracheal tube or an independent bronchial blocker is required, along with flexible fiberoptic bronchoscopy techniques (best continuous monitoring). Correct patient positioning and prevention of complications such as eye or nerve or crashing injuries while the robotic system is used is mandatory. Recognition of the hemodynamic effects of carbon dioxide during insufflation in the chest is required. Cost is higher and outcome is not yet demonstrated to be better as compared to video-assisted thoracic surgery. The possibility for conversion to open thoracotomy should also be kept in mind. Teamwork is mandatory, as well as good communication between all the actors of the operating theatre.

Nonintubated video-assisted thoracic surgery with high-flow oxygen therapy shorten hospital stay.

Background:Nonintubated video-assisted thoracic surgery (VATS) is widely used due to its acceptable postoperative outcomes. Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) has been successfully applied in cases of prolonged difficult intubation and intensive respiratory care in patients receiving VATS lobectomy. Thopaz Digital Chest Drainage System (THOPAZ) provides regulated negative pressure close to the patient’s chest, optimizing drainage of the pleural and mediastinum. We explored the surgical outcomes of nonintubated VATS lung wedge resection and traditional wedge resection with a double-lumen endotracheal tube.Methods:Patients who received nonintubated VATS lung wedge resection (group A, n = 81) and traditional wedge resection with double-lumen endotracheal tube (group B, n = 79) during the period of November 2015 to April 2018 were enrolled in the study. Demographic data and operation outcomes were obtained and analyzed from review of patient medical charts.Results:Group B had significantly longer mean induction and operative times than group A. Similarly, group B suffered greater intraoperative blood loss, longer postoperative hospital stays, and increased chest tube retention times than group A. Group A had higher partial pressure of carbon dioxide levels in both the pre-one-lung and during one-lung ventilation periods than group B. Furthermore, group A showed lower serum pH levels during one-lung ventilation period. However; group A had significantly higher partial pressure of oxygen levels during one-lung ventilation than group B, although the differences in peripheral oxygen saturation were not statistically significant.Conclusion:Our study demonstrated that nonintubated VATS using THRIVE and THOPAZ in lung wedge resection provides measurable benefits to patients.

Effects of Intraoperative Infusion of Esmolol on Systemic and Pulmonary Inflammation in a Porcine Experimental Model of Lung Resection Surgery.

Lung resection surgery (LRS) is associated with systemic and pulmonary inflammation, which can affect postoperative outcomes. Activation of β-adrenergic receptors increases the expression of proinflammatory and anti-inflammatory mediators, and their blockade may attenuate the systemic inflammatory response. The aim of this study was to analyze the effect of a continuous perioperative intravenous perfusion of esmolol on postoperative pulmonary edema in an experimental model of LRS requiring periods of one-lung ventilation (OLV). Twenty-four large white pigs were randomly assigned to 3 groups: control (CON), esmolol (ESM), and sham. The ESM group received an intravenous esmolol bolus (0.5 mg/kg) and then an esmolol infusion (0.05 mg·kg·minute) throughout the procedure. The CON group received the same volume of 0.9% saline solution as the ESM group plus a continual infusion of saline. The sham group underwent a left thoracotomy without LRS or OLV. At the end of the LRS, the animals were awakened, and after 24 hours, they underwent general anesthesia again. Lung biopsies and plasma samples were obtained to analyze the levels and expression of inflammatory mediators, and the animals also received a bronchoalveolar lavage. At 24 hours after the operation, the ESM group had less lung edema and lower expression of the proinflammatory biomarkers tumor necrosis factor (TNF) and interleukin (IL)-1 compared to the CON group for both lung lobes. For the mediastinal lobe biopsies, the mean difference and 95% confidence interval (CI) between the groups for edema, TNF, and IL-1 were 14.3 (95% CI, 5.6-23.1), P = .002; 0.19 (95% CI, 0.07-0.32), P = .002; and 0.13 (95% CI, 0.04-0.22), P = .006, respectively. In the left upper lobe, the mean differences for edema, TNF, and IL-1 were 12.4 (95% CI, 4.2-20.6), P = .003; 0.25 (95% CI, 0.12-0.37), P < .001; and 0.3 (95% CI, 0.08-0.53), P = .009. Our results suggest that esmolol reduces lung edema and inflammatory responses in the intraoperative and postoperative periods in animals that underwent LRS with OLV.

A method for addressing right upper lobe obstruction with right-sided double-lumen endobronchial tubes during surgery: a randomized controlled trial

BackgroundA right-sided double-lumen tube (R-DLT) tends to obstruct the right upper lobe intraoperatively due to anatomical distortion during surgery. If the R-DLT is poorly matched with the patient’s airway anatomy, it will not be possible to correctly replace the tube with a fiberoptic bronchoscope (FOB). In our study, we aimed to explore an efficient method for difficult repositioning caused by right upper lobe occlusion during surgery: repositioning the R-DLT from the right main bronchus into the left main bronchus. The current study was designed to assess the efficacy and safety of this method.MethodsSixty adult patients scheduled to undergo left-sided thoracic surgery were randomly assigned to two groups. With the patient in the right lateral position during surgery, the R-DLT was pulled back to the trachea while being rotated 90° clockwise; it was then either rotated 90° clockwise for placement into the left main bronchus (Group L) or rotated 90° anticlockwise and returned to the right main bronchus (Group R) using FOB guidance. The primary outcomes included clinical performance, which was measured by intubation time, and the quality of lung collapse. A secondary outcome was safety, which was determined according to bronchial injury and vocal cord injury.ResultsThe median intubation time (IQR [range]) required for placement of a R-DLT into the left main bronchus was shorter than the time required for placement into the right main bronchus (15.0 s [IQR, 12.0 to 20.0 s]) vs 23.5 s [IQR, 14.5 to 65.8 s], P = 0.005). The groups showed comparable overall results for the quality of lung collapse during the total period of one-lung ventilation (P = 1.000). The numbers of patients with bronchial injuries or vocal cord injuries were also comparable between groups (Group R, 11/30 vs. Group L 8/30, P = 0.580 for bronchus injuries; Group R, 15/30 vs. Group L 13/30, P = 0.796 for vocal cord injuries).ConclusionsRepositioning a R-DLT from the right main bronchus into the left main bronchus had good clinical performance without causing additional injury. This may be an efficient method for the difficult repositioning of a R-DLT due to right upper lobe occlusion during surgery.Trial registrationChinese Clinical Trial Registry, ChiCTR-IPR-15006933, registered on 15 August 2015.

Hypoxic Pulmonary Vasoconstriction

Hypoxic pulmonary vasoconstriction (HPV) represents a fundamental difference between the pulmonary and systemic circulations. HPV is active in utero, reducing pulmonary blood flow, and in adults helps to match regional ventilation and perfusion although it has little effect in healthy lungs. Many factors affect HPV including pH or PCO2, cardiac output, and several drugs, including antihypertensives. In patients with lung pathology and any patient having one-lung ventilation, HPV contributes to maintaining oxygenation, so anesthesiologists should be aware of the effects of anesthesia on this protective reflex. Intravenous anesthetic drugs have little effect on HPV, but it is attenuated by inhaled anesthetics, although less so with newer agents. The reflex is biphasic, and once the second phase becomes active after about an hour of hypoxia, this pulmonary vasoconstriction takes hours to reverse when normoxia returns. This has significant clinical implications for repeated periods of one-lung ventilation.

Hypoxic pulmonary vasoconstriction: physiology and anesthetic implications.

Hypoxic pulmonary vasoconstriction (HPV) represents a fundamental difference between the pulmonary and systemic circulations. HPV is active in utero, reducing pulmonary blood flow, and in adults helps to match regional ventilation and perfusion although it has little effect in healthy lungs. Many factors affect HPV including pH or PCO2, cardiac output, and several drugs, including antihypertensives. In patients with lung pathology and any patient having one-lung ventilation, HPV contributes to maintaining oxygenation, so anesthesiologists should be aware of the effects of anesthesia on this protective reflex. Intravenous anesthetic drugs have little effect on HPV, but it is attenuated by inhaled anesthetics, although less so with newer agents. The reflex is biphasic, and once the second phase becomes active after about an hour of hypoxia, this pulmonary vasoconstriction takes hours to reverse when normoxia returns. This has significant clinical implications for repeated periods of one-lung ventilation.

Effect of protective ventilation on pro-inflammatory cytokine response during one lung ventilation in esophagectomy: a randomized controlled study

Background: Esophagectomy is associated with increase in pro-inflammatory cytokine whose extent has been claimed as a causative agent of postoperative acute lung injury. Objectives: The aim of this study was to determine whether a ventilatory strategy based on the reduction of tidal volume (VT) and a moderate level of positive end-expiratory pressure (PEEP) during one lung ventilation (OLV) could reduce the pro-inflammatory cytokine response associated with esophagectomy. Also, its impact on oxygenation and postoperative outcome were evaluated. Patients and methods: Thirty patients were randomly allocated into two groups: Group (CV), Patients (n = 15) received a conventional ventilation strategy (tidal volume of 9 ml/kg during two-lung and OLV); no PEEP was applied and group (PV), Patients (n = 15) received a protective ventilation strategy (tidal volume of 9 ml/kg during two-lung ventilation, reduced to 5 ml/kg during OLV and PEEP 5 cm H20 was applied. Serum level of interleukins (IL-6 and IL-8) were measured at baseline time after anesthetic induction (TBaseline,); at the end of abdominal stage of the operation (TAbdo,); at the end of OLV (TOLV end, ); 1 hour and 20 hour after The end of the surgical procedure respectively (TPostop1) and (TPostop20,). Also, peri-operative oxygenation and post-operative outcome were evaluated. Results: There were significant increases in blood level of IL-6 and IL-8 all over the time in both groups in comparison to their baseline values (p= 0.001). However there were significant reduction in blood level of IL-6 and IL-8 in group PV compared to CV group all over the study period (p<0.05). The oxygenation index was significantly higher in PV group during the period of OLV (p< 0.001) and during the first day postoperatively (p< 0.001). There was no significant difference in post-operative outcome between groups. Conclusion: The use of VT 5 ml /kg and PEEP of 5 cm H2O during OLV reduced the systemic pro-inflammatory cytokine response, improved peri-operative oxygenation, but there were no significant differences in occurrence of ARDS or postoperative outcome in patients undergoing esophagectomy.

Efficiency, Efficacy, and Safety of EZ-Blocker Compared with Left-sided Double-lumen Tube for One-lung Ventilation

Double-lumen tubes (DLTs) or bronchial blockers are commonly used for one-lung ventilation. DLTs are sometimes difficult or even impossible to introduce, and the incidence of postoperative hoarseness and airway injuries is higher. Bronchial blockers are more difficult to position and need more frequent intraoperative repositioning. The design of a Y-shaped bronchial blocker, the EZ-Blocker (Teleflex Life Sciences Ltd., Athlone, Ireland) (EZB), combines some advantages of both techniques. The objective of this study was to assess whether EZB performs clinically better than left-sided DLTs (Broncho-cath; Mallinckrodt, Athlone, Ireland) without causing more injury. Primary outcome was the frequency of initial malpositions. Eligible patients were adults scheduled for surgery requiring one-lung ventilation who met criteria for placement of both devices. In this parallel trial, 100 consecutive and blinded patients were assigned randomly using a computer-generated list to two groups. The incidence of malposition and ease and time of placement were recorded. Blinded assessors investigated quality of lung deflation, postoperative complaints, and damage to the airway. Placement of a DLT was unsuccessful twice. The incidence of initial malposition was high and comparable between EZBs (37 of 50) and DLTs (42 of 49) (P = 0.212). Placing single-lumen tubes and EZBs took more time but was rated easier. Quality of lung deflation was comparable. Fewer patients in the EZB group complained of sore throat at day 1. There was a higher incidence of tracheal hematoma and redness and bronchial hematoma in the DLT group. The EZB is an efficient and effective device for one-lung ventilation and causes less injury and sore throat than a DLT.

The changes of pulmonary blood flow in non-ventilated lung during one lung ventilation

A pulmonary artery catheter placement is necessary for intrapulmonary shunt fraction evaluation. The purpose of this study was to investigate the feasibility for detecting the changes of regional pulmonary blood flow in non-ventilated lung by transesophageal echocardiography (TEE) during one-lung ventilation (OLV). 22 adult patients for selective thoracic surgery were enrolled in the study. Doppler flow patterns in left upper pulmonary vein (LUPV) were obtained by TEE before switching to right OLV and every 5 min in 30 min OLV period. Systolic peak velocity (Vs), diastolic peak velocity (Vd) and velocity time integral (VTI) were measured respectively. The VTI of LUPV blood flow pattern decreased significantly 5 min after right OLV. The percent of changes in LUPV blood flow decreased rapidly by 78.4 and 67.7% at OLV 5 min and 10 min, respectively. Then it slowly decreased by 60% at OLV 30 min. Provides an alternative method to measure the changes of pulmonary blood flow during OLV. The percent changes of regional pulmonary blood flow decreased immediately after OLV, and decreased by 60% at 30 min OLV.

How do COPD and healthy-lung patients tolerate the reduced volume ventilation strategy during OLV ventilation.

Although a strategy of tidal volume (V(t)) reduction during the one-lung ventilation (OLV) period is advised in thoracic surgery, the influence of the pre-operative respiratory status on the tolerance of this strategy remains unknown. Therefore, the aim of this study was to compare the pulmonary function between chronic obstructive pulmonary disease (COPD) and healthy-lung patients during the operative and the post-operative period. Forty-eight patients undergoing a planned lobectomy for cancer and presenting either a healthy lung function (n=24) or a moderate COPD stage (n=24) were ventilated without external positive end-expiratory pressure (PEEP) and received 9 ml/kg V(t) during the two-lung ventilation (TLV) period, secondary reduced to 6 ml/kg during the OLV period. Lung function was assessed by peroperative gas exchange, venous admixture, respiratory mechanical parameters and post-operative spirometric measurements. Although the PaO(2) was superior in the healthy-lung group during the TLV, once the OLV was established, no difference was observed between the two groups. Moreover, the PaO(2)/FiO(2) was proportionally more impaired in the healthy-lung group compared with the COPD group (50 ± 13 vs. 72 ± 19% of the baseline values after exclusion and 32 ± 15 vs. 51 ± 25% after the thoracotomy, P<0.05 for each) as well as the venous admixture. In the post-operative period, a higher decrease was observed in the healthy-lung group for the forced vital capacity and the forced expiratory volume. Reducing V(t) to 6 ml/kg without the adjunction of external PEEP during OLV is associated with better preservation of lung function in the case of moderate COPD than in the case of healthy-lung status.

Risk Factors for Post-pneumonectomy Acute Lung Injury/Acute Respiratory Distress Syndrome in Primary Lung Cancer Patients

Acute lung injury/acute respiratory distress syndrome (ALI / ARDS) is the most serious pulmonary complication after lung resection. This study investigated the incidence and outcome of patients with ALI / ARDS who required mechanical ventilation within one week of undergoing pneumonectomy for primary lung cancer and analysed the risk factors. We retrospectively reviewed the medical records of 146 patients who underwent pneumonectomy for primary lung cancer between May 2001 and April 2006. Preoperative, perioperative and postoperative clinical data were analysed. Post-pneumonectomy ALI / ARDS developed within the first postoperative week in 18 (12%) patients. Patients who developed ALI / ARDS had a longer hospital duration of stay (median [interquartile range], 26 [18 to 75] vs. 8 [7 to 11] days; P < 0.001) and higher in-hospital mortality (12 [67%] vs. 0 [0%]; P < 0.001). In an univariate analysis, post-pneumonectomy ALI / ARDS was associated with larger tidal volume (V(T)) and higher airway pressure (P(aw)) during one-lung ventilation (V(T) 8.2 [7.5 to 9.0] vs. 7.7 [6.9 to 8.2] ml/kg predicted body weight, P = 0.016; P(aw), 28.9 [27.6 to 30.0] vs. 27.2 [25.6 to 28.5] cmH2O, P = 0.001). V(T) during two-lung ventilation was also greater in patients who developed ALI / ARDS (P = 0.014) than in those who did not, but P(aw) during two-lung ventilation did not differ (P = 0.950). In a multiple logistic regression analysis, post-pneumonectomy ALI / ARDS was independently associated with a larger V(T) (OR 3.37 per 1 ml/kg predicted body weight increase; 95% confidence interval 1.65 to 6.86) and higher P(aw) (OR 2.32 per 1 cmH2O increase; 95% confidence interval 1.46 to 3.67) during the period of one-lung ventilation. In conclusion, a large V(T) and high P(aw) during one-lung ventilation were associated with an increased risk of post-pneumonectomy ALI / ARDS in primary lung cancer patients.

A Comparison of Transcutaneous and End-tidal Measurements of CO2in One Lung Ventilation

In thoracic anesthesia with one lung ventilation (OLV), end-tidal CO2 (PeTCO2) monitoring may not be accurate to estimate PaCO2 mainly due to ventilation/perfusion mismatching.This study aimed to asses the clinical usefulness and accuracy of a transcutaneous CO2 (PtCCO2) monitoring in thoracic anesthesia, compared with PeTCO2. Methods:18 patients of ASA physical status 1 or 2, required a long period of OLV were researched.The lungs were mechanically ventilated in the lateral decubitus position.We measured PaCO2, PeTCO2, PtCCO2 during two lung ventilation (TLV) and 15 min, 30 min, 60 min after OLV.For comparing the differences of PtCCO2/PaCO2 and PtCCO2/PaCO2, we figured out bias (mean difference between values) and precision (standard deviation of bias) by using Bland-Altman plot.We compared the differences of each value, PeTCO2/PaCO2, PtCCO2/PaCO2, using the student`s t-test. Results:The bias ± precision of PeTCO2/PaCO2 and PtCCO2/PaCO2 was each 7.82 mmHg ± 3.98 mmHg, 1.95 mmHg ± 2.66 mmHg during TLV and that of mean value of PeTCO2/PaCO2 and PtCCO2/PaCO2 was each 6.93 mmHg ± 2.6 mmHg, 2.35 mmHg ± 1.66 mmHg during OLV.PtCCO2/PaCO2 differences were significantly less than PeTCO2/PaCO2 differences (P ＜ 0.05). Conclusions:During one lung ventilation, PtCCO2 monitoring is more useful and accurate than PeTCO2 monitoring for assessing PaCO2 levels.

Gas Exchange and Pulmonary Hemodynamics During Lung Resection in Patients at Increased Risk: Relationship With Preoperative Exercise Testing

Study objectivesTo 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. DesignProspective study. SettingUniversity teaching hospital. PatientsForty patients (mean [± SD] age, 65 ± 9 years) with COPD (ie, FEV1, 55 ± 11% of predicted) and resectable lung neoplasms. InterventionsPreoperatively, 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). ResultsDuring OLV, compared with TLV, the Pao2/fraction of inspired oxygen (Fio2) 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 Po2. Both Pao2 and ▪t during OLV were significantly lower in patients who had undergone right thoracotomies compared with those who had undergone left thoracotomies. The Pao2/Fio2 ratio during OLV correlated with the Pao2 during exercise (r = 0.39; p = 0.01) and with the perfusion of the non-neoplastic lung (r = 0.44; p = 0.005). ConclusionsIn COPD patients, OLV leads to a significant derangement of gas exchange, which is more pronounced in right thoracotomies. Preoperative measurement of Pao2 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.

Anesthetic considerations for thoracic neurosurgical procedures

Anesthetic considerations for thoracic and thoracoscopic neurosurgical procedures are considered, emphasizing the need to provide anesthetic stability during prolonged periods of one-lung ventilation, while optimizing conditions for intraoperative monitoring of spinal cord integrity.

Respiratory mechanics and gas exchange during one-lung ventilation for thoracic surgery: The effects of end-inspiratory pause in stable COPD patients

Objective: To examine the effects of end-inspiratory pause (EIP) of different durations on pulmonary mechanics and gas exchange during one-lung ventilation (OLV) for thoracic surgery. Design: A prospective clinical study. Setting: A university hospital. Participants: Eleven patients undergoing elective pulmonary resection with pulmonary hyperinflation on their preoperative pulmonary function studies. Interventions: Patients were anesthetized, paralyzed, and intubated with a double-lumen endotracheal tube. Their lungs were ventilated with a Siemens 900C ventilator (Siemens; Solna, Sweden), with constant inspiratory flow. Tidal volume, respiratory rate, and inspiratory time were kept constant during the study. Measurements and Results: During one-lung ventilation in the lateral decubitus position, three levels of EIP (0%, 10%, and 30%) were applied to the dependent lung in random order. After 15 minutes on the given ventilatory pattern, end-inspiratory and end-expiratory occlusions of at least 5 seconds were performed to obtain respiratory mechanics data. Arterial blood gas samples were drawn to assess gas exchange. Altering the duration of end-inspiratory pause from 0% to 30% resulted in a significant increase in intrinsic positive end-expiratory pressure (PEEP i) from 4.1 cm H 2O to 7.0 cm H 2O. Arterial oxygenation was significantly decreased from 109.7 to 80.5 mmHg and there was a significant negative correlation between the value of partial pressure of arterial oxygen (PaO 2) and PEEP i by altering the duration of end-inspiratory pause. From the preoperative pulmonary function studies, the value of functional residual capacity (FRC) (% predicted) showed a significant negative correlation with the Pa0 2 changes. Partial pressure of arterial carbon dioxide (PaCO 2) was not altered significantly by increasing the duration of end-inspiratory pause. Conclusion: During the period of OLV in the lateral position of patients with preexisting pulmonary hyperinflation, the magnitude of PEEP i increased and oxygenation decreased significantly, whereas the efficacy of ventilation was not changed by the addition of an end-inspiratory pause to the ventilatory pattern. Because arterial oxygenation is affected by the presence of pulmonary hyperinflation, the method of ventilation should take into account the magnitude of preoperative pulmonary hyperinflation.