Analyzing Hemodynamic Impacts of Two-Lung versus One-Lung Ventilation in Thoracotomy Patients: Insights from Pleth Variability Index and Ultrasonic Cardiac Output Monitoring in a Comparative Study

During one-lung ventilation, ventilation-perfusion mismatch decreases the arterial concentration of inhaled anaesthetics due to the arterial-to-venous concentration difference. This study tested the hypothesis that in humans, the 'presumed effect-site concentration' (taken as the mid-point between the arterial and superior jugular venous concentrations) of inhaled anaesthetic falls during one-lung (vs two-lung) ventilation. Four patients scheduled for elective prostatectomy (two-lung ventilation) and four patients for elective thoracotomy (one-lung ventilation) were randomly selected and assigned to receive sevoflurane (vaporiser-dial setting, 1.5%). Sevoflurane concentrations were measured periodically from radial artery and superior jugular vein (via a catheter advanced cephalad from the jugular vein). During one-lung ventilation, the end-expiratory sevoflurane concentration was stable at ∼1.3% but the mean (SD) presumed effect-site concentration declined initially from 58 (6.7) to 43 (4.7) μg.ml(-1) (p=0.011) before slowly recovering. A period of insufficient depth of anaesthesia is thus a risk during one-lung ventilation.

Background: One lung ventilation (OLV) results in a ventilation-perfusion (V/Q) mismatch. Protective lung ventilation (PLV) reduces postoperative pulmonary complications following OLV. However, PLV predisposes to areas of atelectasis in the ventilated lung and worsens the V/Q mismatch. Aim of Study: To evaluate the gradient between arterial carbon dioxide tension (PaCO2) and partial pressure of end-tidal carbon dioxide gas (ETCO2) during OLV using PLV. The second objective was to see if a high gradient could be predicted based on preoperative pulmonary function tests (PFTs), American Society of Anesthesiologists Physical Status (ASA-PS) or intraoperative haemodynamic changes. Patients and Methods: The PaCO2 and ETCO2 during two lung ventilation (TLV) and OLV were noted with patient in the lateral position. The PaCO2-ETCO2 gradients during TLV and OLV were calculated. The mean values of PaCO2, ETCO2 and PaCO2-ETCO2 gradient were compared for OLV and TLV. For gradients above 8 mm Hg, PFT, ASA-PS grade and blood pressure were assessed to identify any clinical association. Results: Sixty patients were enrolled in the study. The mean values of PaCO2 were 38.17 and 44.02 mm Hg during TLV and OLV respectively. The mean values of ETCO2 were 31.31 and 34.53 mm Hg during TLV and OLV respectively. The mean PaCO2-ETCO2 gradient was 6.74 and 9.71 mm Hg during TLV and OLV respectively. These values were significantly lower during TLV than OLV. Conclusion: ETCO2 does not correspond with PaCO2 during OLV using PLV. It is not possible to predict which patients will show a higher PaCO2-ETCO2 gradient. This study could not find any clinical association between the preoperative PFT, ASA-PS grade or intraoperative haemodynamics when PaCO2-ETCO2 gradient was greater than 8 mm Hg.

Histochemical Alterations in One Lung Ventilation

Unrecognized endobronchial intubation frequently occurs after emergency intubation. However, no study has evaluated the effect of one-lung ventilation on end-tidal carbon dioxide (ETCO2) during cardiopulmonary resuscitation (CPR). We compared the hemodynamic parameters, blood gases, and ETCO2 during one-lung ventilation with those during conventional two-lung ventilation in a pig model of CPR, to determine the effect of the former on ETCO2. A randomized crossover study was conducted in 12 pigs intubated with double-lumen endobronchial tube to achieve lung separation. During CPR, the animals underwent three 5-min ventilation trials based on a randomized crossover design: left-lung, right-lung, or two-lung ventilation. Arterial blood gases were measured at the end of each ventilation trial. Ventilation was provided using the same tidal volume throughout the ventilation trials. Comparison using generalized linear mixed model revealed no significant group effects with respect to aortic pressure, coronary perfusion pressure, and carotid blood flow; however, significant group effect in terms of ETCO2 was found (P < 0.001). In the post hoc analyses, ETCO2 was lower during the right-lung ventilation than during the two-lung (P = 0.006) or left-lung ventilation (P < 0.001). However, no difference in ETCO2 was detected between the left-lung and two-lung ventilations. The partial pressure of arterial carbon dioxide (PaCO2), partial pressure of arterial oxygen (PaO2), and oxygen saturation (SaO2) differed among the three types of ventilation (P = 0.003, P = 0.001, and P = 0.001, respectively). The post hoc analyses revealed a higher PaCO2, lower PaO2, and lower SaO2 during right-lung ventilation than during two-lung or left-lung ventilation. However, the levels of these blood gases did not differ between the left-lung and two-lung ventilations. In a pig model of CPR, ETCO2 was significantly lower during right-lung ventilation than during two-lung ventilation. However, interestingly, ETCO2 during left-lung ventilation was comparable to that during two-lung ventilation.

To assess agreement between the ultrasonic cardiac output monitor (USCOM) and conventional echocardiography (ECHO) in the measurement of cardiac output in newborn infants, investigate the accuracy and clinical utility of the USCOM in healthy neonates. To explore a more convenient, faster, more accurate hemodynamic monitoring method, for improving the outcome of the critically ill neonates. From October 1(st), 2011 to March 31(st), 2012, a total of 49 infants were included, 20 were term infants, 29 were preterm infants. Cardiac outputs were measured by both ultrasonic cardiac output monitor and echocardiography in all the infants, 60 times measurements were done in both the term infants the preterm infants. The cardiac output of the left and right ventricles, heart rate, diameter and velocity time integral of the aortic valve and pulmonary artery valve of each infant were recorded. The consistency of two methods was analyzed as described by Bland-Altman. Term the term infant group includea 20 term infants, 11 were male and 9 were female, the mean gestational age were (38.1 ± 0.56) weeks, mean age were (2 ± 1) days, mean weight were (3.2 ± 0.29) kg, mean Apgar score were 10. The mean left ventricular output measured by Echo was (242.3 ± 38.9) ml/(kg·min), measured by USCOM was (211.7 ± 38.5) ml/(kg·min); The mean right ventricular output measured by ECHO was (318.9 ± 47.0) ml/(kg·min), measured by USCOM was (340.7 ± 76) ml/(kg·min). Agreement between Echo and USCOM for left ventricular output (LVO) was (bias, ± limits of agreement, mean % error): (30.6 ± 51.1) ml/(kg·min), 21%, and for right ventricular output (RVO): (-21.8 ± 105) ml/(kg·min), 33.2%. The diameter of the aortic valve and pulmonary artery valve measured by conventional echocardiography were significantly larger than that estimated by ultrasonic cardiac output monitor (P < 0.001). The velocity time integral of the pulmonary artery valve measured by ultrasonic cardiac output monitor were significantly larger than measured by conventional echocardiography (P < 0.001). The heart rate, velocity time integral of the aortic valve measured by two methods had no significant differences (P > 0.05). The preterm neonates group included 29 preterm infants, 18 were male and 11 were female, the mean gestational age were (32.6 ± 2.8) weeks, mean age were (2 ± 1) days, mean weight were (1.88 ± 0.57) kg. All the infants were diagnosis as preterm infant, low birth weight. The mean left ventricular output measured by ECHO was (259.8 ± 70) ml/(kg·min), measured by USCOM was (235.6 ± 61.8) ml/(kg·min), the mean right ventricular output measured by ECHO was (318.9 ± 47.0) ml/(kg·min), measured by USCOM was (340.7 ± 76) ml/(kg·min). Agreement between Echo and USCOM for left ventricular output (LVO) was (bias, ± limits of agreement, mean % error): (24.1 ± 71.2) ml/(kg·min), 27.4%, and for right ventricular output (RVO): (-29.5 ± 192.9) ml/(kg·min), 51.8%. The diameter of the aortic valve and pulmonary artery valve measured by conventional echocardiography were significantly larger than estimated by ultrasonic cardiac output monitor (P < 0.001). The velocity time integral of the pulmonary artery valve measured by USCOM were significantly larger than that measured by conventional echocardiography (P < 0.001). The heart rate, velocity time integral of the aortic valve measured by two methods had no significant differences (P > 0.05). Agreement between USCOM and conventional ECHO in the LVO measurement is acceptable, both in the term group and the preterm group. LVO measurement measured by USCOM is recommended. The accuracy and clinical utility of the USCOM in neonates is acceptable. USCOM is a convenient, fast and accurate hemodynamic monitoring method in neonates. While the agreement between USCOM and conventional ECHO in the RVO measurement is poor, especially in the preterm group, the results of the RVO cannot be considered interchangeable in the two methods.

Objective To observe the effect of one-lung ventilation (OLV) or two-lung ventilation (TLV) on pulmonary uptake of sevoflurane.Methods Fifteen patients with esophageal tumorectomy and fifteen patients with stomach tumorectomy were selected for OLV and TLV during the operation,respectively.Sevoflurane was used for the general anesthesia.Bispectral index (BIS),Fi and Et were recorded at each measurement point,and Et/Fi was calculated.Results The BIS value of OLV group was higher than that of TLV group (P＜0.05),Et/Fi in OLV group was higher than TLV group (P＜0.01).OLV group:the BIS value gradually decreased and reached into an anesthetic state (BIS:60) at 5 min,and then enough anesthesia depth (BIS:40-60) was maintained during 5 min-120 min.Et gradually increased and reached into a steady state at 30 min.Et/Fi increased and reached into a steady state at 50 min,and the Et/Fi during 50 min-120 min had no statistical significance (P＞0.05).TLV group:the BIS value gradually decreased and reached into an anesthetic state at 2 min,and then enough anesthesia depth was maintained during 2 min-70 min.However,the BIS value was less than 40 after 70 min.Et gradually increased and reached into a steady state at 20 min.Et/Fi gradually increased and reached into a steady state at 2 min,and the Et/Fi during 2 min-120 min had no statistical significance (P＞0.05).Conclusions OLV had an effect on pulmonary uptake of sevoflurane.The total amount of sevoflurane uptake in OLV was less than that in TLV,while the uptake rate of OLV during 2 min-50 min was faster than that of TLV.Both OLV and TLV could supply a surgery-needed anesthetic depth with sevoflurane inhalant concentration 3％vol.However,inhalant concentration should be adjusted after 70 min to avoid excessive anesthesia during TLV.Furthermore,the anesthetic depth of OLV was less than that of TLV,and OLV needed a longer time to reach into a steady state compared with TLV. Key words: One-lung ventilation; Sevoflurane; Pulmonary uptake; Bispectral Index; Et

End-tidal carbon dioxide tension (PETCO2) is widely used to estimate arterial carbon dioxide tension (PaCO2) under various clinical conditions. This study was conducted to determine if PETCO2 during one lung ventilation (OLV) is as useful as PETCO2 during two lung ventilation (TLV) for predicting PaCO2. Methods: Forty patients undergoing thoracic surgery were enrolled in this study. During OLV (n = 20) and TLV (n = 20), PaCO2 and PETCO2 were measured. The arterial-end tidal carbon dioxide difference (Pa-ETCO2) was then calculated and a correlation between PaCO2 and PETCO2 was evaluated during OLV and TLV. Results: Pa-ETCO2 was significantly higher during OLV (8.9 ± 5.1 mmHg) than during TLV (6.1 ± 3.9 mmHg). In addition, the correlation between PETCO2 and PaCO2 was less significant during OLV (R2 = 0.43) than during TLV (R2 = 0.59). Conclusions: PETCO2 during OLV was not as accurate as PETCO2 during TLV for predicting PaCO2, which indicates that greater attention should be given to the maintenance of normocarbia during OLV than during TLV.

To evaluate cardiopulmonary effects of one-lung ventilation (OLV) versus two-lung ventilation (TLV) in closed-chest anesthetized dogs. Controlled, randomized experiment. Fourteen, 2- to 7-year-old adult dogs, weighing 23 +/- 6 kg. The dogs were anesthetized with acepromazine, morphine, thiopental, and halothane in oxygen, ventilated, and paralyzed with vecuronium. Tidal volume was 10 mL/kg. Respiratory rate was set to maintain end-tidal CO2 (ETCO2) at 40 +/- 2 mm Hg before instrumentation then not changed. The left bronchus of 7 dogs was obstructed with a Univent bronchial blocker (Fuji Systems Corp, Tokyo, Japan). Blood gas analysis and hemodynamic measurements were taken at predetermined intervals for 1 hour in the TLV group and at baseline and following bronchial obstruction in the OLV group. Shunt fraction was not significantly different between groups, but in OLV shunt increased from baseline at 5 minutes. Arterial oxygen (PaO2) decreased after baseline in OLV compared with TLV. Arterial carbon dioxide (PaCO2) increased with OLV and decreased with TLV. In OLV, systemic vascular resistance was variable and decreased compared with TLV. Cardiac index increased over time in both groups but was not affected by treatment. Heart rate, mean arterial pressure, and diastolic arterial pressure increased with OLV compared with TLV but did not change over time. This study shows that OLV statistically decreases oxygen tension and transiently increases shunt fraction, but with 100% O2 it appears to be a feasible procedure with minimal cardiopulmonary side effects in healthy dogs. OLV is a feasible procedure in anesthetized dogs to better facilitate thoracic procedures such as bronchopleural fistula repair and thoracoscopy.

Video-assisted thoracoscopic surgery (VATS) has emerged as an innovative and popular procedure for the management of postpneumonic empyema in children refractory to medical response. Alternative uses of two- and one-lung ventilations have been required during VATS. This study evaluated the efficacy of alternating one- and two-lung ventilation through intraoperatively through the same single-lumen endobronchial tube using a tube exchanger during a thoracoscopic procedure for pediatric empyema. Between May 1995 and August 2001, 62 consecutive pediatric patients undergoing VATS for evacuation of the loculated empyema cavity were studied. The same single-lumen endobronchial tube was used, with an indwelling endotracheal tube exchanger in place for readjustment of the tube position to provide alternation of one- and two-lung ventilations in a thoracosopic procedure. Duration of operation, heart rate, mean arterial pressure, peak airway pressure, an partial pressure of oxygen (PaO(2)) and carbon dioxide (PaCO(2)) changes during one- and two-lung ventilations were recorded. The quality of lung deflation and inflation was rated by the surgeon using direct visualization as excellent, fair or poor. The mean operating time was 90 min (range, 50-120 min). No differences were found in heart rate, mean arterial pressure, or PaO(2) during one- and two-lung ventilations. Peak airway pressure and PaCO(2) during two-lung ventilation were significantly higher than during one-lung ventilation. The quality of lung deflation and inflation was judged excellent for all the patients. The VATS procedure can be performed safely and effectively in children using proper anesthetic technique. Retention of a tube exchanger within a single-lumen endobronchial tube an easily provide alternative one- and two-lung ventilations without inducing any significant airway flow obstruction during the operation.

Background: One-lung ventilation (OLV) is often required to facilitate surgical exposure. Hypoxemia is a common disorder during thoracic surgery. Objectives: We studied whether changing from the supine to the lateral position during OLV and two-lung ventilation (TLV) in thoracic surgery would affect positions on arterial oxygen pressure (PaO2) in two groups of smokers and nonsmokers. Methods: This single-blinded prospective observational pilot study was conducted on patients who underwent thoracotomy under general anesthesia. The effect of lateral and supine PaO2 was investigated in 15 patients with a history of smoking (≥ 40 packs/year) and 15 patients without. The data were analyzed via descriptive and inferential statistics in SPSS v. 19. Results: Arterial oxygen pressure did not significantly differ between the two groups in the supine TLV (P = 0.98), supine OLV (P = 0.16), lateral TLV (P = 0.06), and lateral OLV (P = 0.31). However, the PaO2 level was higher in smokers than in nonsmokers (except during supine TLV). Changing the position from supine to lateral caused a relative decrease in PaO2 (except during TLV in smokers) during TLV and OLV. This reduction in PaO2 levels was less in smokers (72.12) than in nonsmokers (95.28). Oxygen saturation (SpO2) levels were the same in all positions regardless of whether they were a smoker or nonsmoker. Conclusions: Changing the position from supine to lateral had no significant effects on PaO2 and SpO2 levels in smoker and nonsmoker patients during OLV and TLV in thoracic surgery.

Hypoxemia May Occur After Endobronchial Valve Deployment—The Mechanism Is Speculative at Present

Invasive and noninvasive cardiovascular monitoring options for cardiac surgery

Objective To investigate the effect of dexmedetomidine pretreatment on the expression of caspase-12 in lung tissues undergoing one-lung ventilation(OLV)in rats. Methods Thirty male Sprague-Dawley rats, aged 6–8 weeks, weighing 180–220 g, were randomly allocated into 3 groups(n=10 each)using a random number table: two-lung ventilation(TLV)group, OLV group and dexmedetomidine group(Dex group). Bilateral lungs were ventilated for 2 h in group TLV.In OLV and Dex groups, unilateral lung was ventilated for 1.5 h followed by 0.5 h TLV.In group Dex, dexmedetomidine was infused intravenously at a rate of 3.0 μg·kg–1·h–1 over 60 min starting from 60 min prior to OLV.The equal volume of normal saline was given instead of dexmedetomidine in OLV and TLV groups.Peak airway pressure(Ppeak)and mean airway pressure(Paw)were recorded at 45 min of OLV and 15 min of TLV in OLV and Dex groups, and at 15 min of TLV in group TLV.The rats were then sacrificed, and left lungs were removed for microscopic examination of the pathologic changes(using HE staining)and the ultrastructure of lung tissues(with transmission electron microscope)and for determination of wet to dry lung weight ratio(W/D ratio), cell apoptosis in lung tissues(by TUNEL), caspase-12 mRNA expression(using real-time reverse transcriptase-polymerase chain reaction), and caspase-12 expression(by Western blot). Results Ppeak and Paw were significantly lower at 15 min of TLV than at 45 min of OLV in OLV and Dex groups(P<0.05). Compared to group TLV, W/D ratio and AI were significantly increased, and the expression of caspase-12 protein and mRNA was up-regulated in OLV and Dex groups(P<0.01). Compared to group OLV, W/D ratio and AI were significantly decreased, and the expression of caspase-12 protein and mRNA was down-regulated in group Dex(P<0.01). The pathologic changes of lung tissues were significantly alleviated in group Dex as compared with group OLV. Conclusion The mechanism by which dexmedetomidine pretreatment alleviates acute lung injury caused by OLV is associated with down-regulated expression of caspase-12 and inhibited cell apoptosis in rats. Key words: Dexmedetomidine; Respiration, artificial; Respiratory distress syndrome, adult; Caspase 12

Nurse-determined assessment of cardiac output. Comparing a non-invasive cardiac output device and pulmonary artery catheter: A prospective observational study

One-lung ventilation (OLV) is the standard and widely applied ventilation approach used in video-assisted thoracoscopic surgery for esophageal cancer (VATS-e). To address the disadvantages of OLV with respect to difficulties in intubation and induction, as well as the risk of respiratory complications, two-lung ventilation (TLV) with artificial pneumothorax has been introduced for use in VATS-e. However, no studies have yet compared TLV and OLV with postoperative infection and inflammation in the prone position over time postoperatively. Here, we investigated the efficacy of TLV in patients undergoing VATS-e in the prone position. Between April 2010 and December 2016, 119 patients underwent VATS-e under OLV or TLV with carbon dioxide insufflation. Clinical characteristics, surgical outcomes, and postoperative outcomes, including oxygenation and systemic inflammatory responses, were compared between patients who underwent OLV and those who underwent TLV. Clinical characteristics other than pT stage were comparable between groups. The TLV group had shorter thoracic operation time than the OLV group. No patients underwent conversion to open thoracotomy. The PaO2/FiO2 ratios of the TLV group on postoperative day (POD) 5 and on POD7 were significantly higher than those of the OLV group. C-reactive protein levels on POD7 were lower in the TLV group than in the OLV group. There were no significant differences with respect to postoperative complications between the OLV and TLV groups. In the TLV group, the white blood cell count on POD7 was significantly lower than that in the OLV group; body temperature showed a similar trend immediately after surgery and on POD1. In this study, we demonstrated that, compared with OLV, TLV in the prone position provides better oxygenation and reduced inflammation in the postoperative course. Accordingly, TLV might be more useful than OLV for ventilation during esophageal cancer surgery.