Association Between Cerebral Desaturation and Postoperative Delirium in Thoracotomy With One-Lung Ventilation: A Prospective Cohort Study.

BACKGROUND: The association between cerebral desaturation and postoperative delirium in thoracotomy with one-lung ventilation (OLV) has not been specifically studied. METHODS: A prospective observational study performed in thoracic surgical patients. Cerebral tissue oxygen saturation (Scto2) was monitored on the left and right foreheads using a near-infrared spectroscopy oximeter. Baseline Scto2 was measured with patients awake and breathing room air. The minimum Scto2 was the lowest measurement at any time during surgery. Cerebral desaturation and hypersaturation were an episode of Scto2 below and above a given threshold for ≥15 seconds during surgery, respectively. The thresholds based on relative changes by referring to the baseline measurement were <80%, <85%, <90%, <95%, and <100% baseline for desaturation and >105%, >110%, >115%, and >120% baseline for hypersaturation. The thresholds based on absolute values were <50%, <55%, <60%, <65%, and <70% for desaturation and >75%, >80%, >85%, and >90% for hypersaturation. The given area under the threshold (AUT)/area above the threshold (AAT) was analyzed. Delirium was assessed until postoperative day 5. The primary analysis was the association between the minimum Scto2 and delirium using multivariable logistic regression controlled for confounders (age, OLV time, use of midazolam, occurrence of hypotension, and severity of pain). The secondary analysis was the association between cerebral desaturation/hypersaturation and delirium, and between the AUT/AAT and delirium using multivariable logistic regression controlled for the same confounders. Multiple testing was corrected using the Holm-Bonferroni method. We additionally monitored somatic tissue oxygen saturation on the forearm and upper thigh. RESULTS: Delirium occurred in 35 (20%) of 175 patients (65 ± 6 years old). The minimum left or right Scto2 was not associated with delirium. Cerebral desaturation defined by <90% baseline for left Scto2 (odds ratio [OR], 5.82; 95% confidence interval [CI], 2.12-19.2; corrected P =.008) and <85% baseline for right Scto2 (OR, 4.27; 95% CI, 1.77-11.0; corrected P =.01) was associated with an increased risk of delirium. Cerebral desaturation defined by other thresholds, cerebral hypersaturation, the AUT/AAT, and somatic desaturation and hypersaturation were all not associated with delirium. CONCLUSIONS: Cerebral desaturation defined by <90% baseline for left Scto2 and <85% baseline for right Scto2, but not the minimum Scto2, may be associated with an increased risk of postthoracotomy delirium. The validity of these thresholds needs to be tested by randomized controlled trials.

The Effects of Secondhand Smoke Exposure on Postoperative Pain and Ventilation Values During One-Lung Ventilation: A Prospective Clinical Trial.

OBJECTIVES: To investigate the relationships between secondhand smoke (SHS) exposure and oxygenation during one-lung ventilation (OLV) in lobectomy surgery and between SHS exposure and postoperative analgesic consumption. DESIGN: Prospective study. SETTING: University, Faculty of Medicine, operating room. PARTICIPANTS: Sixty adult patients with American Society of Anesthesiologists score II to III, aged 18 to 65 years, with a body mass index (BMI) <35 kg/m2 scheduled for lobectomy surgery by open thoracotomy. INTERVENTIONS: Patients were divided into 2 groups: the SHS group (n = 30) (urine cotinine level ≥6.0 ng/mL) and the NS (nonsmoker) group (n = 30) (urine cotinine level <6.0 ng/mL and no smoking history). SHS exposure was defined according to a previously published algorithm. MEASUREMENTS AND MAIN RESULTS: Noninvasive blood pressure, electrocardiography, capnography, and peripheral oxygen saturation were monitored, and intra- and postoperative arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2), and intraoperative peak airway pressure were compared between the 2 groups. Postoperative analgesic consumption was calculated. No significant differences in demographics or preoperative data were noted between the 2 groups. PaO2 values 10 minutes after OLV onset and 10 minutes after the end of OLV were increased significantly in the NS group compared with those in the SHS group (p < 0.05). PaO2 values after 10 minutes of OLV in the NS and SHS groups were 285.5 ± 90 mmHg and 186.7 ± 66 mmHg, respectively. PaO2 values after OLV termination in the NS and SHS groups were 365.8 ± 58 mmHg and 283.6 ± 64 mmHg (p < 0.05), respectively. PaCO2 values 10 minutes after OLV onset, 10 minutes after the end of OLV, at the end of surgery, and upon arrival in the intermediate care unit were significantly different between the 2 groups (p < 0.05). CONCLUSION: The present study demonstrated that during OLV, patients exposed to SHS exhibited significantly lower arterial oxygen pressure compared with nonsmokers. Arterial carbon dioxide values were increased significantly in SHS-exposed patients. Morphine consumption for postoperative analgesia also was increased in patients exposed to SHS compared with that in nonsmokers.

The Effects of an Open-Lung Approach During One-Lung Ventilation on Postoperative Pulmonary Complications and Driving Pressure: A Descriptive, Multicenter National Study.

OBJECTIVE: Thoracic surgical procedures are associated with an increased risk of postoperative pulmonary complications (PPCs), which seem to be related directly to intraoperative driving pressure. The authors conducted this study to describe the incidence of PPCs in patients in whom an individualized open-lung approach was applied during one-lung ventilation. DESIGN: This was a prospective, multicenter, national descriptive study. SETTING: Thoracic surgery patients undergoing one-lung ventilation. PARTICIPANTS: Eligible participants were included consecutively from October 1, 2016, to September 30, 2017. A total of 690 patients were included. INTERVENTIONS: An individualized open-lung approach that consisted of an alveolar recruitment maneuver followed by a positive end-expiratory pressure adjusted to best respiratory system compliance was performed in all patients. MEASUREMENTS AND MAIN RESULTS: Preoperative and intraoperative data were recorded; the primary outcome was a description of the incidence of PPCs in these patients during the first 7 postoperative days. The patients were mainly male, and half of them had a high risk of PPCs (ARISCAT score exceeding 44). Eleven percent of participants developed a PPC within the first postoperative week. The mean open lung positive end-expiratory pressure was 8 ± 3 cmH2O. When compared with pre-open lung approach values, the open-lung approach significantly decreased the driving pressure (14 ± 4 cmH2O v 11 ± 3 cmH2O; p < 0.001) and increased dynamic compliance (30 ± 10 mL/cmH2O v 43 ±15 mL/cmH2O; p < 0.001). CONCLUSIONS: The low incidence of PPCs in patients who underwent an open-lung approach during one-lung ventilation compared with that reported for other thoracic surgery series and the decrease in the driving pressure in these patients justify an additional randomized controlled trial to compare the open-lung approach with the standard protective strategy of low tidal volume and low positive end-expiratory pressure.

Management of 1-Lung Ventilation-Variation and Trends in Clinical Practice: A Report From the Multicenter Perioperative Outcomes Group.

BACKGROUND: Lung-protective ventilation (LPV) has been demonstrated to improve clinical outcomes in surgical patients. There are very limited data on the current use of LPV for patients undergoing 1-lung ventilation (1LV) despite evidence that 1LV may be a particularly important setting for its use. In this multicenter study, we report trends in ventilation practice for patients undergoing 1LV. METHODS: The Multicenter Perioperative Outcomes Group database was used to identify patients undergoing 1LV. We retrieved and calculated median initial and overall tidal volume (VT) for the cohort and for high-risk subgroups (female sex, obesity [body mass index >30 kg/m], and short stature), percentage of patients receiving positive end-expiratory pressure (PEEP) ≥5 cm H2O, LPV during 1LV (VT ≤ 6 mL/kg predicted body weight [PBW] and PEEP ≥5 cm H2O), and ventilator driving pressure (ΔP; plateau airway pressure - PEEP). RESULTS: Data from 5609 patients across 4 institutions were included in the analysis. Median VT was calculated for each case and since the data were normally distributed, the mean is reported for the entire cohort and subgroups. Mean of median VT during 1LV for the cohort was 6.49 ± 1.82 mL/kg PBW. VT (mL/kg PBW) for high-risk subgroups was significantly higher; 6.86 ± 1.97 for body mass index ≥30 kg/m, 7.05 ± 1.92 for female patients, and 7.33 ± 2.01 for short stature patients. Mean of the median VT declined significantly over the study period (from 6.88 to 5.72; P < .001), and the proportion of patients receiving LPV increased significantly over the study period (from 9.1% to 54.6%; P < .001). These changes coincided with a significant decrease in ΔP during the study period, from 19.4 cm H2O during period 1 to 17.3 cm H2O in period 12 (P = .003). CONCLUSIONS: Despite a growing awareness of the importance of protective ventilation, a large proportion of patients undergoing 1LV continue to receive VT PEEP levels outside of recommended thresholds. Moreover, VT remains higher and LPV less common in high-risk subgroups, potentially placing them at elevated risk for iatrogenic lung injury.

Impact of Low Tidal Volumes During One-Lung Ventilation. A Meta-Analysis of Randomized Controlled Trials.

OBJECTIVES: The link between ventilation strategies and perioperative outcomes remains one of the fundamental paradigms of thoracic anaesthesia. During one-lung ventilation (OLV), one lung is excluded from gas exchange and ventilation is directed at the dependent lung. The authors hypothesised that the use of low tidal volumes (VT) during OLV provides adequate gas exchange and improves postoperative outcome. DESIGN: Meta-analysis of randomized clinical trials. SETTING: Thoracic surgery. PARTICIPANTS: Patients undergoing OLV. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The authors performed a meta-analysis of all randomized trials on low versus high VT during OLV in patients undergoing thoracic surgery. Outcomes of the study were gas exchange and airway pressures during and after OLV, postoperative pulmonary complications (PPCs), and hospital stay (HLOS). Fourteen randomized trials were selected, but only a few of them contained one outcome of interest. Low VT was associated with lower arterial oxygen tension, lower airway pressures, and higher arterial carbon dioxide tension at specific time points during OLV. Low VT was associated with preserved gas exchange after OLV, lower incidence of pulmonary infiltrations, and acute respiratory distress syndrome. Incidences of PPCs and HLOS were similar. CONCLUSIONS: The use of low VT reduces airway pressure but worsens gas exchange during OLV. Preservation of postoperative oxygenation and reduction in infiltrates suggest a lung-protective modality with no demonstrable impact on PPCs and HLOS.

Impact of Left Heart Bypass on Arterial Oxygenation During One-Lung Ventilation for Thoracic Aortic Surgery.

OBJECTIVE: The aim of this study was to reveal the mechanism of improved arterial oxygenation by measuring the changes in oxygenation before and after initiation of left heart bypass (LHB) during one-lung ventilation (OLV) for thoracic aortic surgery. DESIGN: Prospective, observational study. SETTING: Single-institution, private hospital. PARTICIPANTS: The study comprised 50 patients who underwent aortic surgery via a left thoracotomy approach with LHB circulatory support. INTERVENTIONS: Patients were ventilated using pure oxygen during OLV, and the ventilator setting was left unchanged during the measurement period. MEASUREMENTS AND MAIN RESULTS: The measurement of partial pressure of arterial oxygen (PaO2) was made at the following 4 time points: 2 minutes after heparin infusion (point 1 [P1]), 2 minutes after inflow cannula insertion through the left pulmonary vein (P2), immediately before LHB initiation (P3), and 10 minutes after LHB initiation (P4). The mean±standard deviation (mmHg) of PaO2 measurements at the P1, P2, P3, and P4 time points were 244±121, 250±123, 419±122, and 430±109, respectively, with significant increases between P1 and P3, P1 and P4, P2 and P3, and P2 and P4 (p<0.0001, respectively). No significant increase in PaO2 was seen between P1 and P2 or between P3 and P4. CONCLUSIONS: The improved arterial oxygenation during OLV in patients who underwent thoracic aortic surgery using LHB can be attributed to the insertion of an inflow cannula via the left pulmonary vein into the left atrium before LHB.