A Pilot Study on the Association of Mitochondrial Oxygen Metabolism and Gas Exchange During Cardiopulmonary Exercise Testing: Is There a Mitochondrial Threshold?

Objective To observe the effects of lateral position plus jacknife position on difference of partial pressure of carbon dioxide in artery and end-tidal pressure of carbon dioxide[P(a-ET）CO2].Methods Thirty-six patients undergoing elective surgery under total intravenous anesthesia were involved.Patients were divided into two groups (n=18):control group (group C) and experimental group (group L).Patients undergoing abdominal surgery were at supine position in group C.Patients undergoing nephrectomy,ureterolithotomy surgery or adrenal cyst resection were at lateral position plus jacknife position.Patients were endotracheal intubation and mechanical ventilation,respiratory rate was 15 rpm,inspiratory/expiratory ratio was 1∶1.5.End-tidal pressure of carbon dioxide(PETCO2) was stable between 30 mmHg-35 mmHg (1 mm Hg=0.133 kPa).Blood gas analysis was done at 15 (T1),35 min (T2) and PETCO2 was stable (T0)(the fluctuation was less than 1 mmHg).The ventilator parameters were not been constant during T0-T2 At T1,patients' position were changed from supine position to lateral position plus jacknife position in group L,and patients' position remained supine position in group C.Intraoperative monitoring consisted of electrocardiogram,invasive arterial pressure,heart rate,pulse oxygen saturation,tidal volume,minute ventilation,peak of airway pressure,end-tidal pressure of carbon dioxide(PETCO2),and so on.Results PETCO2,partial pressure of carbon dioxide in artery(PaCO2) and P(a-ET)CO2 were respectively (28.4±2.3),(35.7±3.3),(7.2±3.0) mmHg at T2 in group L.In group L,those items were(32.2± 1.8),(34.2±2.0),(2.6±2.8) mmHg at T1 respectively(P＜O.05).P(a-ET)CO2 were(2.6±2.5) and (3.1 ±1.5) mmHg at T1 and T2 respectively in group C.Compared with group L,P (aET)CO2 were significantly lower (P＜0.05).Conclusions P (a-ET)CO2 was significantly increases at lateral position plus jacknife position.So the ventilator parameters should be adjusted according PETCO2. Key words: Lateral position; Jackknife position; End-tidal pressure of carbon dioxide ; Hemodynamics; Blood gas analysis

Objective To evaluate the accuracy of continuous noninvasive partial pressure of carbon dioxide monitoring in the old diabetic patients undergoing general anesthesia. Methods Sixty-six old diabetic patients of both sexes, aged 65-76 yr, weighing 49-95 kg, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, undergoing elective surgery under general anesthesia, were included in this study.Transcutaneous partial pressure of carbon dioxide(TcPCO2)was monitored by a noninvasive transcutaneous carbon dioxide monitor.Arterial blood samples were collected at 30 and 60 min after endotracheal intubation, partial pressure of arterial carbon dioxide(PaCO2)was monitored, and TcPCO2 and end-tidal pressure of carbon dioxide(PETCO2)were recorded.Bland-Altman analysis was used to measure the agreement. Results At 30 min after intubation, the results of Bland-Altman analysis showed that the mean difference between PaCO2 and TcPCO2 was 1.3, 95% confidence interval(CI)was 1.0-1.6, and the limit of agreement was -1.1-3.7; the mean difference between PaCO2 and PETCO2 was -3.2, 95%CI: -3.6--2.8, and the limit of agreement was -6.6-0.2.At 60 min after intubation, the results of Bland-Altman analysis showed that the mean difference between PaCO2 and TcPCO2 was 1.4, 95% CI was 1.1-1.7, and the limit of agreement was -1.0-3.4; the mean difference between PaCO2 and PETCO2 was -3.1, 95%CI was -3.5--2.7, and the limit of agreement was -6.7-0.5.The repeatability coefficients of PaCO2, TcPCO2 and PETCO2 were 2.1, 2.3 and 2.3, respectively, at 30 and 60 min after intubation. Conclusion Continuous noninvasive partial pressure of carbon dioxide monitoring provides good accuracy and can be used as an alternative to PaCO2 monitoring, and the accuracy is higher than that of PETCO2 for the old diabetic patients undergoing general anesthesia. Key words: Carbon dioxide; Monitoring, physiologic; Diabetes mellitus; Anesthesia, general

BackgroundThe purpose of this study was to analyze cardiopulmonary fitness in Phase I cardiac rehabilitation on the prognosis of patients with ST-Elevation Myocardial Infarction (STEMI) after percutaneous coronary intervention (PCI).MethodsThe study enrolled a total of 499 STEMI patients treated with PCI between January 2015 and December 2015. Patients were assigned to individualized exercise prescriptions (IEP) group and non-individualized exercise prescriptions (NIEP) group according to whether they accept or refuse individualized exercise prescriptions. We compared the incidence of major cardiovascular events between the two groups. IEP group were further divided into two subgroups based on prognosis status, namely good prognosis (GP) group and poor prognosis (PP) group. Key cardio-pulmonary exercise testing (CPX) variables that may affect the prognosis of patients were identified through comparison of the cardio-respiratory fitness (CRF).ResultsThere is no significant difference in the incidence of cardio-genetic death, re-hospitalization, heart failure, stroke, or atrial fibrillation between the IEP and the NIEP group. But the incidence of total major adverse cardiac events (MACE) was significantly lower in the IEP group than in the NIEP group (P = 0.039). The oxygen consumption (VO2) at ventilation threshold (VT), minute CO2 ventilation (E-VCO2), margin of minute ventilation carbon dioxide production (△CO2), rest partial pressure of end-tidal carbon dioxide(R-PETCO2), exercise partial pressure of end-tidal carbon dioxide(E-PETCO2) and margin of partial pressure of end-tidal carbon dioxide(△PETCO2) were significantly higher in the GP subgroup than in the PP subgroup; and the slope for minute ventilation/carbon dioxide production (VE/VCO2) was significantly lower in GP subgroup than in PP subgroup (P = 0.010). The VO2 at VT, VE/VCO2 slope, E-VCO2, △CO2, R-PETCO2, E-PETCO2 and margin of partial pressure of end-tidal carbon dioxide CO2 (△PETCO2) were predictive of adverse events. The VO2 at VT was an independent risk factor for cardiovascular disease prognosis.ConclusionsIndividualized exercise prescription of Phase I cardiac rehabilitation reduced the incidence of cardiovascular events in patients with STEMI after PCI. VO2 at VT is an independent risk factor for cardiovascular disease prognosis, and could be used as an important evaluating indicator for Phase I cardiac rehabilitation.

In patients with systolic heart failure, the ability of cardiopulmonary exercise testing (CPX) variables to reflect pathophysiology is well established. The relationship between CPX and pathophysiology has, however, not been thoroughly investigated in patients with nonobstructive hypertrophic cardiomyopathy (NHCM). The objective of this study was to assess the ability of CPX variables to reflect resting hemodynamics in patients with nonobstructive hypertrophic cardiomyopathy NHCM. We performed CPX and right heart catheterization on 83 subjects with NHCM (51 male/32 female, mean age = 38 +/- 10 yr, NYHA I-III mean = 1.7). Peak oxygen consumption ( O2) and minute ventilation/carbon dioxide ratio (V E/VCO2) at peak exercise were compared to resting hemodynamics including pulmonary artery systolic, diastolic and mean pressures (PASP, PADP and MPAP), and pulmonary capillary wedge pressure (PCWP). Elevations in PCWP (> or = 15 mm Hg), PASP (> or =30 and > or = 40 mm Hg), PADP (> 15 mm Hg) and MPAP (> or = 20 mm Hg) were detected in 22, 33, 10, and 23% of subjects, respectively. Peak V E/VCO2 (positive correlation) and peak VO2 (negative correlation) correlated modestly with all pressure measurements (r = 0.33-0.51, P < 0.01 for all measurements). By receiver operating curve analysis, a V E/VCO2 >35.5 exhibited the best diagnostic accuracy with a curve areas of 0.81 for PAP > or = 30 mm Hg (sensitivity/specificity = 86%/67%), 0.87 for PAP > or = 40 mm Hg (77%/100%), 0.86 for MPAP > 20 mm Hg (83%/79%), and 0.84 for PCWP > or = 15 mm Hg (80%/76%). CPX can accurately identify abnormal resting hemodynamics in patients with NHCM. Further testing of this modality in other forms of diastolic dysfunction may be warranted.

This study compares two noninvasive techniques for monitoring the partial pressure of carbon dioxide (PCO2) in 24 anesthetized adult patients. End-tidal PCO2 (PetCO2) and transcutaneous PCO2 (PtcCO2) were simultaneously monitored and compared with arterial PCO2 (PaCO2) determined by intermittent analysis of arterial blood samples. PETCO2 and PtcCO2 values were compared with PaCO2 values corrected to patient body temperature (PaCO2T) and PaCO2 values determined at a temperature of 37 degrees C (PaCO2). Linear regression was performed along with calculations of the correlation coefficient (r), bias, and precision of the four paired variables: PETCO2 versus PaCO2 and PaCO2T (n = 211), and PtcCO2 versus PaCO2 and PaCO2T (n = 233). Bias is defined as the mean difference between paired values, whereas precision is the standard deviation of the difference. The following values were found for r, bias, and +/- precision, respectively. PETCO2 versus PaCO2: 0.67, -7.8 mm Hg, +/- 6.1 mm Hg; PETCO2 versus PaCO2T: 0.73, -5.8 mm Hg, +/- 5.9 mm Hg; PtcCO2 versus PaCO2: 0.87, -1.6 mm Hg, +/- 4.3 mm Hg; PtcCO2 versus PaCO2T: 0.84, +0.7 mm Hg, +/- 4.8 mm Hg. Although each of these PCO2 variables is physiologically different, there is a significant correlation (P less than 0.001) between the noninvasively monitored values and the blood gas values. Temperature correction of the arterial values (PaCO2T) slightly improved the correlation, with respect to PETCO2, but it had the opposite effect for PtcCO2. In this study, the chief distinction between these two noninvasive monitors was that PETCO2 had a large negative bias, whereas PtcCO2 had a small bias. We conclude from these data that PtcCO2 may be used to estimate PaCO2 with an accuracy similar to that of PETCO2 in anesthetized patients.

This study is based on the theory of Holistic Integrative Physiology and Medicine (HIPM), which emphasizes a comprehensive understanding of the interplay of respiratory-circulatory-metabolic integration regulation. Within this theory, we recognize that left heart failure (LHF) and right heart failure (RHF) present distinct pathophysiological profiles, especially when assessed through cardiopulmonary exercise testing (CPET). We seek to elucidate the similarities and differences in CPET responses between LHF and RHF, thereby enhancing our understanding of their unique exercise pathophysiology. In this retrospective study, we included 123 patients diagnosed with LHF and 101 patients with RHF, all of whom were treated at Fuwai Hospital between 2018 and 2023. Each patient underwent standard CPET, along with routine medical examinations. During the CPET, we calculated the key parameters, identified the presence of oscillatory breathing (OB), and assessed the occurrence of exercise-induced right-to-left shunting (R-LShunt) using standard methodologies. Additionally, a control group comprising 81 normal subjects (NS) also underwent CPET to provide a baseline for comparison. The data collected from all three groups-LHF patients, RHF patients, and NS-were then subjected to a comprehensive analysis. We used analysis of variance (ANOVA)-based statistical methods to analyze the differences in CPET parameters among these groups. Peak oxygen uptake ( ) in LHF [48.04±17.14 percentage of predicted (%pred)] and RHF (53.68±15.10 %pred) was significantly lower than in NS (85.37±14.01 %pred) (NS versus LHF and RHF, both P<0.001). Notably, the LHF demonstrated markedly lower exercise capacity in both peak (%pred) and anaerobic threshold (AT, %pred), but higher oxygen uptake efficiency plateau (OUEP, %pred) than the RHF group (P=0.008, 0.009, and <0.001, respectively). In the LHF group, OB manifestations were observed in 72 cases (59%), and in the RHF group, R-LShunt manifestations appeared in 64 cases (63%). Within the LHF subgroup, those with OB showed a significantly lower peak (39.95±12.84 %pred) compared to those without OB (59.46±15.99 %pred, P<0.001). In the RHF group, peak was also lower in the R-LShunt subgroup (50.1±12.52 %pred) compared to the no R-LShunt subgroup (59.87±17.24 %pred, P=0.001). Additionally, the R-LShunt group displayed an aberrant pattern of almost persistently decreased partial pressure of end-tidal carbon dioxide (PETCO2) during CPET. LHF patients exhibited lower exercise tolerance, in contrast to RHF patients, but showed a relatively small decrease in gas exchange capacity. Nevertheless, both LHF and RHF exhibited general functional limitations during CPET. Notably, patients exhibiting OB in the context of LHF, and those with R-LShunt in RHF, presented with even more pronounced functional limitations compared to their counterparts without these specific pathophysiological features.

Continuous determination of the cerebrovascular changes induced by bicuculline and kainic acid in unanaesthetized spontaneously breathing rats

Background Ventilation strategies during general anesthesia are crucial for optimizing respiratory mechanics, ensuring adequate oxygenation, and minimizing postoperative pulmonary complications (PPCs) in surgical patients. This systematic review and network meta-analysis (NMA) aim to evaluate the effect of pressure controlled volume guaranteed ventilation (PCV-VG) in patients undergoing non-cardiothoracic surgery. Methods We selected randomized controlled trials (RCTs) to explore the effect of PCV-VG mode on intraoperative respiratory mechanics, oxygenation and PPCs in surgical patients published in English by searching PubMed, Embase, Web of Science, and the Cochrane from inception to May 2025. The primary outcome was dynamic lung compliance (Cdyn). Results Fourteen studies with 2263 patients were included. Compared to volume-controlled ventilation (VCV), PCV-VG had higher Cdyn and lower airway peak pressure (Ppeak). For tidal volume (Vt), partial pressure of carbon dioxide in arterial blood (PaCO2), partial pressure of oxygen in arterial blood (PaO2), oxygenation index (OI), airway mean pressure (Pmean), and PPCs, there were no significant difference among pressure-controlled ventilation (PCV), VCV, and PCV-VG. Compared to VCV, PCV-VG did not significantly affect the values of potential of hydrogen (pH) and partial pressure of end-tidal carbon dioxide (PetCO2). The subgroup analysis only showed that PCV had higher Cdyn than VCV in prone position. Conclusions PCV-VG was superior to VCV in Cdyn and Ppeak, PCV only achieved higher Cdyn than VCV for prone position. The three modes did not differ in Vt, Pmean, PetCO2, pH, PaCO2, PaO2, OI, and PPCs for patients undergoing non-cardiothoracic surgery.

BackgroundArterial oxygenation is often impaired during one-lung ventilation (OLV), due to both pulmonary shunt and atelectasis. Lower fraction of inspiration O2 (FiO2) may reduce inflammation and complications, but may increase the risk of hypoxemia. The aim of this randomized controlled parallel trial was to analyze whether higher positive end-expiratory pressure (PEEP) could improve oxygenation and maintain lower levels of inflammation during OLV under a lower FiO2.MethodsOne hundred and twenty patients with selective thoracotomy for esophageal cancer (EC) were classified randomly into four groups on a ratio of 1:1:1:1 using a computer-generated list, including Group A (FiO2 =0.6, PEEP =0), Group B (FiO2 =0.6, PEEP =5 cmH2O), Group C (FiO2 =1.0, PEEP =8 cmH2O), and Group D (FiO2 =1.0, PEEP =10 cmH2O). The oxygenation and pulmonary shunt were primary outcomes. Haemodynamics, respiratory mechanics, serum IL-6 and IL-10 levels, and complications were taken as secondary outcomes. Follow-up was terminated until discharge.ResultsTwo patients in Group A and two in Group D were excluded due to hypoxemia and hypotension, respectively. Then the data of 116 patients (Group A =28, Group B =30 Group C =30, and Group D =28) were assessed for final analysis. Compared with Group B, the partial pressure of oxygen (PaO2) and dynamic compliance during OLV in Group D were significantly increased from 15 minutes to 60 minutes, while pulmonary shunt was significantly decreased (P>0.05). Patients in Group D had higher levels of central venous pressure (CVP) and airway pressure (Paw) during OLV and higher levels of IL-6 and IL-10 after OLV compared with Group B (P>0.05). No statistical differences were found in oxygen saturation (SaO2), PvO2 (partial pressure of oxygen in venous blood), partial pressure of end-tidal carbon dioxide (ETCO2), partial pressure of carbon dioxide in artery (PaCO2), heart rate (HR), mean arterial pressure (MAP), and complications among the four groups (P>0.05).ConclusionsHigher PEEP increased the oxygenation under 60% O2 during OLV. However, the haemodynamics and respiratory mechanics changed, and the levels of inflammation increased. A higher PEEP under 60% O2 during OLV is not recommended.Trial RegistrationChinese Clinical Trial Registry ChiCTR1900024726.

The effects of surgical technique on respiratory mechanics, arterial oxygenation and hemodynamics in radical prostatectomy operation were investigated. The study was planned on ASA II-III, 40-65 years old, fourty patients scheduled for radical prostatectomy under general anesthesia. They were divided into two groups: perineal and suprapubic (Group P, n = 20; Group S, n = 20). Heart rate, mean arterial blood pressure, arterial oxygen saturation (SpO2), partial pressure of end-tidal carbon dioxide (PEtCO2), Peak inspiratory pressure (PIP), plato pressure (Pplato), partial pressure of oxygen in arterial blood (PaO2), partial pressure of carbon dioxide in arterial blood (PaCO2) values were evaluated at 10 minutes after induction. After the position applied for surgery in the 30.60 and 90th minutes, the Alveolar-arterial oxygen pressure gradient (P(A-a) O2), the ratio of physiologic dead space over tidal volume (VD/VT), arterial to end tidal CO2 gradient (P(a-et) CO2), static compliance (CS), dynamic compliance (CD) were assessed. In the assessment of groups, there were not statistical differences about mean blood pressure, heart rate, SpO2, PetCO2, PaO2, plateau pressure, and P (A-a) values (p &gt; 0.05). Peak inspiratory pressure was higher in Group P. Peak inspiratory pressure and plateau pressure increased with CO2 insufflation in Group P. PaCO2 and P(a-et) CO2 were higher statistically significantly in Group 0. There was no difference in terms of the PetCO2 values. VD/VT ratios were statistically significantly lower in the Group P. Suprapubic surgery was shown to improve oxygenation and respiratory mechanics without causing any hemodynamic side effect in radical prostatectomy operation.

Objective: The effects of 10cmH2O Positive End-expiratory Pressure (PEEP) on respiratory mechanics, arterial oxygenation and hemodynamics in laparoscopic cholecystectomy operation were investigated. Methods: The study was planned on ASA I-II, 18-65 years old, forty patients scheduled for laparoscopic cholecystectomy under general anesthesia. The patients were divided into two groups which PEEP implemented Group 0 and 10 cmH2O PEEP applied Group P (Group 0, n=20; Group P, n=20). Heart rate, Mean arterial blood pressure, arterial oxygen saturation (SpO2), partial pressure of end-tidal carbon dioxide (PEtCO2), Peak inspiratory pressure (PİP), plato pressure (Pplato), partial pressure of oxygen in arterial blood (PaO2), partial pressure of carbon dioxide in arterial blood (PaCO2 ) values were evaluated at 5 minutes after induction, 5 minutes after CO2 insufflation, after the head-up position and the right side in the 10th and 30th minutes, After 10 minutes desufflation and in the recovery room. The Alveolar–arterial oxygen pressure gradient (P(A-a) O2), the ratio of physiologic dead space over tidal volume (VD/VT), Arterial to End Tidal CO2 gradient (P(a-et) CO2), static compliance (CS), dynamic compliance (CD) were assessed same times. Results: The assessment between the groups, there were not statistical differences about mean blood pressure, heart rate, SpO2, PetCO2, PaO2, plateau pressure, and P (A-a) values (p>0.05). Peak inspiratory pressure was higher in Group P (p<0.05). Peak inspiratory pressure and plateau pressure increased with CO2 insufflation in both groups. PaCO2 and P(a-et) CO2 were higher statistically significantly in Group 0 (p<0.05). There was no difference between the groups in terms of the PetCO2 values. VD/VT ratios were statistically significantly lower in the Group P (p<0.05). There was no difference at static compliance values between the groups, dynamic compliance was lower in Group P. According to the initial values, there was a decrease in compliance in both groups after CO2 insufflation. Conclusion: 10 cmH2O PEEP was shown to improve oxygenation and respiratory mechanics without causing any hemodynamic side effect in laparoscopic cholecystectomy operation.

The early introduction of a rehabilitation procedure is of vital importance in the process of acting upon the respiratory system. In comprehensive therapy, pulmonary rehabilitation is perceived as an integral part of treatment for mechanically ventilated patients. The aim of this work was to conduct a comparative analysis of pulmonary rehabilitation concerning patients who had sustained an injury as the result of traffic collisions, and were subsequently treated in an intensive care unit (ICU). Research material consisted of information contained in the medical documentation of 43 patients, ranging in ages from 15 to 57 years, treated in the ICU for injuries sustained during traffic collisions. This analysis involved the values of the parameters recorded first on admission of the patient to the unit, and then every 7 days thereafter, and finally upon discharge from the ICU, and included: arterial blood gasometry, pulsoxymetry, capnometry, body temperature, arterial blood pressure, and pulse rate. Pneumonia occurred most frequently in patients ventilated mechanically during the period from the 15 th to the 28 th day of hospitalization and constituted 60% of the total occurring pneumonias. Deaths were observed more often in patients with acidosis and hypercapnia. Values of arterial oxygen saturation of hemoglobin (SaO 2 ) below 94% were recorded in that group of patients for whom therapeutic procedures ended in failure (40%). For the remaining patients, SaO 2 values exceeded 94%. The analysis of our material showed divergences concerning the values of partial pressure of end-tidal carbon dioxide (PetCO 2 ) and partial pressure of carbon dioxide in the arterial blood (PaCO 2 ). The mean values of SaO 2 and percutaneous monitoring of hemoglobin oxygen saturation (SpO 2 ) were similar. The length of stay within the ICU is significant with respect to the occurrence of complications in the form of pneumonia. Patients whose parameter values were within the norm during pulmonary rehabilitation attained spontaneous respiration at discharge. SpO 2 and PetCO 2 are of vital importance in the pulmonary rehabilitation process, complemented by regularly taken arterial blood gasometry measurements.

To evaluate the effect of transnasal humidified rapid insufflation ventilatory exchange (THRIVE) on regional cerebral oxygen saturation (rScO2) during induction of general anesthesia in patients undergoing traumatic brain injury (TBI) emergency surgery. A prospective randomized controlled trial was conducted. The TBI emergency general anesthesia patients who underwent intracranial hematoma removal surgery at the Northern Jiangsu People's Hospital from January to July in 2023 were enrolled. The patients were divided into a conventional mask ventilation group and a THRIVE group using a random number table method. The patients in the conventional mask ventilation group were anesthetized and induced to pre oxygenate without positive pressure ventilation in the front mask for 10 minutes, with an oxygen flow rate of 8 L/min and an fraction of inspired oxygen (FiO2) of 1.00. After anesthesia induction for about 90 s, tracheal intubation was performed after the muscle relaxant took effect (patient's jaw muscle was relaxed). The patients in the THRIVE group were pre oxygenated with THRIVE for 10 minutes, with an oxygen flow rate of 30 L/min and a FiO2 of 1.00. During anesthesia induction, the oxygen flow rate was increased to 50 L/min, and anesthesia induction medication was used. The lower jaw of patient was supported with both hands to maintain airway patency, and the patient's mouth was kept closed throughout the process. After the muscle relaxant took effect (the patient's jaw muscle was relaxed), tracheal intubation was performed. At the time of patient entering the operating room, 10 minutes of pre oxygenation, and immediately after successful intubation, rScO2 was measured on the surgical and non-surgical sides. At the same time, ultrasound was used to measure the cross-sectional area (CSA) of the gastric antrum and arterial blood gas analysis was performed. The partial pressure of end-tidal carbon dioxide (PETCO2) during the first mechanical ventilation after successful tracheal intubation, the incidence of hypoxemia [pulse oxygen saturation (SpO2) < 0.95] during tracheal intubation, as well as prognostic indicators such as the length of intensive care unit (ICU) stay, total length of hospital stay, and Glasgow outcome scale (GOS) score at discharge were recorded. During the study period, a total of 70 TBI patients underwent emergency general anesthesia surgery, of which 2 patients died postoperatively, 2 patients were unable to cooperate with closed mouth breathing, and 3 patients had poor ultrasound image acquisition in the gastric antrum, all of whom were excluded. A total of 63 patients were ultimately enrolled, including 32 in the conventional mask ventilation group and 31 in the THRIVE group. There were no statistically significant differences in gender, age, body mass index (BMI), American Society of Anesthesiologists (ASA) classification, Glasgow coma scale (GCS) score, optic nerve sheath diameter (ONSD), baseline vital signs, fasting situation, anesthesia time, surgical time, and intraoperative blood loss between the patients in the two groups, indicating comparability. When entering the operating room, there was no statistically significant difference in rScO2 on the surgical and non-surgical sides, and blood gas analysis indexes arterial partial pressure of oxygen (PaO2) and arterial partial pressure of carbon dioxide (PaCO2) between the patients in the two groups. When pre oxygenated for 10 minutes, both the surgical and non-surgical sides rScO2 levels in the THRIVE group were significantly higher than those in the conventional mask ventilation group (surgical side: 0.709±0.036 vs. 0.636±0.028, non-surgical side: 0.791±0.016 vs. 0.712±0.027, both P < 0.01), and the PaO2 was significantly increased [mmHg (1 mmHg ≈ 0.133 kPa): 450.23±60.99 vs. 264.88±49.33, P < 0.01], PaCO2 was significantly reduced (mmHg: 37.81±3.65 vs. 43.59±3.76, P < 0.01), and the advantage continues tilled immediately after successful intubation. There was no statistically significant difference in CSA at each time point of ultrasound examination between the two groups. Compared with the conventional mask ventilation group, the patients in the THRIVE group showed a significant decrease in PETCO2 during the first mechanical ventilation after successful tracheal intubation (mmHg: 43.10±2.66 vs. 49.22±3.31, P < 0.01), and the incidence of hypoxemia during tracheal intubation was also significantly reduced [0% (0/31) vs. 28.12% (9/32), P < 0.01]. In terms of prognostic indicators, there was no statistically significant difference in the length of ICU stay and total length of hospital stay between the patients in the conventional mask ventilation group and the THRIVE group [length of ICU stay (days): 10 (9, 10) vs. 10 (9, 11), total length of hospital stay (days): 28.00 (26.00, 28.75) vs. 28.00 (27.00, 29.00), both P > 0.05]. However, the proportion of patients in the THRIVE group with a good prognosis at discharge (GOS score > 3) was significantly higher than that in the conventional mask ventilation group [35.5% (11/31) vs. 12.5% (4/32), P < 0.05]. THRIVE can significantly increase rScO2 during anesthesia induction in TBI emergency surgery patients and improve their neurological function prognosis.

Bispectral index (BIS) and entropy measure electroencephalographic voltage between electrodes placed on the forehead. BIS is used to monitor and quantify depth of hypnosis1and to guide anesthetic drug administration during general anesthesia.2Entropy assesses loss of consciousness by the quantification of the degree of spatial and temporal integration of cerebral neuronal activity.3An entropy monitor has been introduced recently; it provides two indices, state entropy and response entropy, that decrease in healthy volunteers receiving propofol with a brief intervening period of wakefulness4and in surgical patients during propofol anesthetic induction.5We report two cases of perioperative gas embolism encountered during laparoscopic surgery while patients were being monitored simultaneously by BIS (Aspect A-2000 XP®, version 3.11; Aspect Medical Systems, Newton, MA) and entropy of electroencephalogram (S/5™ M-Entropy plug-in Module; Datex-Ohmeda Company, Limonest, France).In our first case, an 83-yr-old man was scheduled for a laparoscopic hemicolectomy under general anesthesia. Target-controlled infusion of propofol and remifentanil was achieved using a computer-assisted infusion device6while atracurium was administered continuously after a bolus. Standard monitoring was used as was BIS and entropy monitoring. Pneumoperitoneum was achieved with carbon dioxide. The first 90 min of anesthesia and surgery were uneventful. Suddenly, BIS and entropy indices dropped to zero as shown in figure 1. Partial pressure of end-tidal carbon dioxide decreased a few seconds later from 28 mmHg to 19 mmHg and arterial hypotension of 80/45 mmHg was noted (it was previously 149/85 mmHg). The surgeon reported no bleeding. Gas embolism was suspected, and the dramatic change in electroencephalographic-derived indices led to immediate exsufflation and conversion to laparotomy. BIS and entropy remained at low values for approximately 25 min with almost 100% burst suppression even after hemodynamic stability was restored. The colectomy was completed, the anesthetic was discontinued, and the patient awoke. Neurologic examination was performed and was normal. Transesophageal echocardiography performed the day after surgery confirmed a patent foramen ovale.In our second case, a 46-yr-old woman was scheduled for a laparoscopic cholecystectomy. Anesthesia and monitoring were similar to case 1. Shortly after the onset of carbon dioxide insufflation, partial pressure of end-tidal carbon dioxide suddenly decreased from 32 to 10 mmHg and arterial pressure decreased to less than 60 mmHg. BIS and entropy values decreased to approximately 20 and the burst suppression ratio was 80% within seconds. Laparoscopy showed a tear in the surface of the liver. The pneumoperitoneum was immediately exsufflated, and a laparotomy was performed. BIS and entropy values regained their former values within 5 min, but arterial pressure and partial pressure of end-tidal carbon dioxide remained low for 15 min. Cholecystectomy was performed. Transesophageal echocardiography performed during anesthesia revealed no septal defect. Anesthesia was discontinued at the end of the procedure and the patient awoke. Neurologic examination was normal.Sudden decreases in BIS have been reported at the onset of clinical deterioration. England was the first to describe the changes in BIS during a hypovolemic cardiac arrest.7An acute decrease in BIS can reflect cerebral hypoperfusion8–10or cerebral embolization.11An alternative explanation for an acute decrease in electroencephalographic-derived indices is an increase in plasma concentration of an anesthetic drug, especially propofol, as a result of rapid alteration of its elimination.12Our two cases showed simultaneous acute and profound decrease of BIS and entropy indices that forced the anesthesiologist to react quickly. After verification of good signal quality, the low level of electromyogram, the stability of anesthetic drug concentrations and the absence of acute bleeding, the diagnosis of gas embolism was made; this is a known complication of laparoscopic surgery. Using transesophageal echocardiography, a very sensitive method of detection, Derouin et al. reported gas embolism in 11 of 16 patients undergoing laparoscopic cholecystectomy.13The clinical impact of gas embolization can be as serious as cardiac arrest;14however, in most instances there are no lasting effects, probably because of the high solubility of carbon dioxide bubbles. Electroencephalographic monitoring modified the surgical and anesthetic management in our two cases. The chronology of events varied between the cases. In the first case, carbon dioxide bubbles reached the brain very rapidly through the patent foramen ovale; BIS and entropy values decreased before any significant changes in other parameters. Other methods of early detection of paradoxical gas embolism have been reported during laparoscopic cholecystectomy; by transesophageal echocardiography15and by transcranial Doppler.16In our second case, in which a patent foramen ovale was ruled out, the decrease of BIS and entropy was observed after hemodynamic and respiratory parameters changed and was transient, reflecting a decrease in cardiac output as a result of gas embolization.Finally, anesthesiologists should be aware of the potential for venous gas embolization during routine laparoscopic procedures; BIS or entropy monitoring may play a role in early detection and could complement routine monitoring.* Foch Hospital, Suresnes, France. m.fischler@hopital-foch.org.

:Background:Both end-tidal carbon dioxide pressure (ETCO2) is used routinely as an indicator of arterial partial pressure of carbon dioxide (PaCO2) and thus adequacy of ventilation. Accurate determination of the PaCO2 level in neuroanesthesia is quite important because of its effect on cerebral blood flow and also hyperventilation is often used to reduce intracranial pressure in neurosurgical patients. This study was aimed to evaluate the relationship between ETCO2 and arterial PaCO2 in neurosurgical patients undergoing craniotomy to assess the predictive value of ETCO2 as an indicator of PaCO2 level.Methods:Forty-five consecutive adult patients with inclusion criteria, scheduled to undergo elective craniotomy surgery were enrolled in this prospective study. Measurements of PaCO2 and ETCO2 were performed at three different intervals: Time 1: 10 min after induction of general anesthesia; time 2: after cranium opening prior to dural incision; and at time 3: start of dural closure. All patients received the same anesthetic agent (propofol, sufentanil, atracurium, oxygen). Data were initially analyzed using Pearson’s Correlation to assess the relationship between PaCO2 and ETCO2 at different stages of the operation. A p-value (P) of less than 0.05 was considered significant. The agreement between the measures of CO2 was assessed using Bland-Altman method, where mean difference and average between PaCO2 and ETCO2 were calculated. The 95% confidence intervals for the lower and upper limits of agreement were presented.Results:A total of 44 patients, aged 18 to 65 years, ASA grades 1 and 2 were participated in the study. Mean difference, standard deviation and correlation coefficient of the parameters were calculated for three time periods. The values for PaCO2, ETCO2, (PaCO2- ETCO2), and correlation coefficient for 10 min after anesthetic induction, prior to dural incision, and start of dural closure were 35.4 ± 3.2, 32.1 ± 3.2, 3.8 ± 2.1, and 0.565, 36.2 ± 3.1, 32.6 ± 3.2,4.8 ± 3.1, and 0.574, and 36.7 ± 2.4, 33 ± 3.2,3.8 ± 2.3, and 0.627, respectively (p less than 0.01 for all analyses). The greatest mean difference occurred just prior to dural incision. The lowest mean difference was observed at 10 min post-anesthetic induction. Conclusions:To the present study was aimed to correlate between End-tidal and arterial carbon dioxide partial pressure in neurosurgical patients undergoing craniotomy. Findings of this study showed that ETCO2 consistently underestimates the value of PaCO2 during craniotomy indicating that ETCO2 value can be used instead of PaCO2.Keywords:End-tidal carbon dioxide pressure, Arterial partial pressure of carbon dioxide, Craniotomy