Compound A and carbon monoxide production from sevoflurane and seven different types of carbon dioxide absorbent in a patient model

Background: The degradation of sevoflurane can lead to the production of compound A (CA) and carbon monoxide (CO) and an increase in temperature of the absorbent. CA is known to be nephrotoxic in rats. These reactions depend on the strong base and water contents of the carbon dioxide absorbent used. The purpose of this study was to measure the maximum amounts of CA and CO produced, and the temperature increase, for seven different carbon dioxide absorbents for sevoflurane containing different contents of strong bases. Methods: Seven absorbents [some free of strong bases (f)] were employed in hydrated (h) and completely desiccated (d) conditions in a patient model, using a circle anesthesia system connected to an artificial lung. Low‐flow anesthesia with an oxygen–nitrous oxide mixture was maintained using 0.8% sevoflurane. For the quantification of CA and CO, a portable gas chromatograph was used. The temperature was measured inside the absorbent. Results: In consecutive order of CA‐producing potency, Amsorb^®(f)(d), Drägersorb(h), Medisorb^®(h), lithium hydroxide(f)(d), Drägersorb(d), Medisorb^®(d), Spherasorb^®(h) and Spherasorb^®(d) produced small amounts of CA. Loflosorb^® and Superia^®, which are free of strong bases, did not produce any CA or CO in hydrated or desiccated conditions. Only desiccated Drägersorb^®, Medisorb^® and Spherasorb^® demonstrated small amounts of CO accompanied by a significant temperature increase. Conclusion: In this patient model, we demonstrated that different types of absorbent produced small amounts of CA and CO or none at all. No relationship could be established between temperature and CA concentration.     

Production of compound A and carbon monoxide in circle systems: an in vitro comparison of two carbon dioxide absorbents

Two new generation carbon dioxide absorbents, DrägerSorb^® Free and Amsorb^® Plus, were studied in vitro for formation of compound A or carbon monoxide, during minimal gas flow (500 ml.min^?1) with sevoflurane or desflurane. Compound A was assessed by gas chromatography/mass spectrometry and carbon monoxide with continuous infrared spectrometry. Fresh and dehydrated absorbents were studied. Mean (SD) time till exhaustion (inspiratory carbon dioxide concentration ≥ 1 kPa) with fresh absorbents was longer with DrägerSorb^® Free (1233 (55) min) than with Amsorb^® Plus (1025 (55) min; p < 0.01). For both absorbents, values of compound A were < 1 ppm and therefore below clinically significant levels, but were up to 0.25 ppm higher with DrägerSorb^® Free than with Amsorb^® Plus. Using dehydrated absorbents, values of compound A were about 50% lower than with fresh absorbents and were identical for DrägerSorb^® Free and Amsorb^® Plus. With dehydrated absorbents, no detectable carbon monoxide was found with desflurane.     

模拟紧闭环路内不同的碱石灰对地氟烷分解反应的比较

目的 研究模拟紧闭环路内三种成分不同的十燥碱石灰与地氟烷发生分解反应生成一氧化碳(CO)的差异。方法 选用钡石灰、国产钠石灰及Sofnolime。在麻醉机的Y-piece端接一贮气囊做为模拟肺。二氧化碳(CO_2)以200ml·min~(-1)的流速通入环路。设定分钟通气量6L·min~(-1),呼吸频率(RR)12次/min,使P_(ET)CO_2在35～45 mm Hg。根据碱石灰的种类不同将实验分为三组,每组实验重复三次。向环路内通入二氧化碳及氧气的同时开启蒸发罐,洗入期开始,当呼气未地氟烷浓度达9％时关闭蒸发罐及新鲜气流,紧闭环路,继续机械通气直至180min。监测 P_(ET)CO_2、重复吸入CO_2分压、地氟烷的吸入、呼出浓度及上下罐反应温度。用气相色谱仪测定CO浓度。结果 三种碱石灰分解地氟烷生成CO的峰浓度及平均浓度由高到低的顺序依次是钡石灰、Sofnolime及国产钠石灰。钡石灰组CO达峰浓度时间明显快于其它两组(P<0.05)。与上罐相比下罐温度上升时间延迟。国产钠石灰组洗入时间较其余两组短。在温度上升期钠石灰组上罐温度上升速度快而钡石灰组下罐温度上升速度快。结论 在模拟紧闭环路内,使用钡石灰发生CO中毒的危险性要高于钠石灰。但仅仅去除钠石灰中的KOH,不能减少吸入全麻药的分解,相反生成CO的量可能增多。     

低流量七氟烷吸入麻醉时不同二氧化碳吸收剂环路中化合物A浓度的比较及其对患者肝肾功能的影响

Objective To investigate the influence of different carbon dioxide (CO2) absorbents (Dr(a)gersorb 800 plus , Sodasorb,Sodasorb LF) on the production of compound A during low-flow sevoflurane anesthesia.Methods Twenty-seven ASA Ⅰ or Ⅱ patients aged 20-64 years were randomly assigned to three groups according to different CO2 absorbents: Dr(a)gersorb 800 plus' group (group D, n = 10), Sodasorb group (group S, n = 10) and Sodasorb LF group (group LF, n = 7). Anesthesia was maintained with low-flow (500 ml/min) sevoflurane inhalation (with the end-tidal sevoflurane concentration of approximately 2% ). At 2 h after low-flow sevoflurane anesthesia, gas samples were taken from the expiratory limb of the circuit. Compound A was detected by gas chromatography. Serum alanine transaminase (ALT), aspartate aminotransferase (AST), bilirubin (BR), urea nitrogen (BUN) and creatinine (Cr) levels were measured before (T0 ) and 24 h after operation (T1).Results The three groups were comparable with respect to age, body weight and height. After 2 h of low-flow sevoflurane anesthesia, compound A concentrations in the expiratory limb of the circuit were 11.6 ± 5.8 (group D), 2.1 ± 1.9 (group S)and ＜ 0.1 ppm (group LF), respectively. There were no significant changes in the serum ALT, AST, BR, BUN and Cr levels at 24 h after operation as compared with the preoperative baseline values in the three groups.Conclusion After 2 h of low-flow (500 ml/min) sevoflurane anesthesia, compound A concentrations within the circuit with different CO2 absorbents ( Dr(a)gersorb 800 plus' , Sodasorb, Sodasorb LF) are less than 50 ppm, with the lowest in Sodasorb LF.However, they have no significant effects on hepatic or renal function.     

Different benefit of bispectal index (BIS) in desflurane and propofol anesthesia

BACKGROUND: Bispectal index (BIS) monitoring may reduce drug usage and hasten recovery in propofol and inhalation anesthesia. The faster emergence profile of desflurane may reduce the effect of BIS monitoring on recovery from desflurane compared with propofol. This study compared hypnotic drug usage, recovery, patient satisfaction and incidence of inadequate sedation in BIS monitored and nonmonitored women anesthetized with desflurane or propofol. METHODS: One hundred and sixty patients scheduled for elective gynecological surgery were randomly assigned to desflurane or propofol anesthesia with and without BIS monitoring. Fentanyl, vecuronium and remifentanil were administered according to clinical criteria. The BIS monitor was used in all patients, but the monitor screen was covered in the controls. A BIS level between 45 and 55 was targeted in the BIS monitored patients whereas depth of anesthesia was assessed by clinical criteria in the controls. RESULTS: The mean (SD) desflurane MAC-hours administered with and without BIS were 0.70 (0.15) and 0.76 (0.12), respectively, resulting in extubation times of 6.5 (4.1) and 8.3 (6.1) min. (NS). Bispectal index monitoring was associated with improved patient satisfaction, reduced postoperative nausea and antiemetic drug requirement, and fewer episodes with sustained BIS levels > 60. The mean (SD) propofol infusion rates were 6.0 (1.4) and 6.6 (0.9) mg kg(-1)h(-1) with and without the BIS monitor (P = 0.023), resulting in mean (SD) extubation times of 6.8 (4.6) and 10.5 min (5.9), respectively (P < 0.05). CONCLUSION: Bispectal index monitoring reduced propofol usage and hastened recovery after propofol anesthesia, whereas in desflurane anesthesia it was associated with improved patient satisfaction, probably because of decreased postoperative nausea and fewer episodes of inadequate hypnosis.     

The in vitro performance of carbon dioxide absorbents with and without strong alkali

We report the in vitro longevity of a conventional soda lime carbon dioxide absorbent and an absorbent free from strong alkali (Amsorb). Although the times taken to breakthrough of carbon dioxide (> 0.5%) within an in vitro low flow breathing system were shorter with the alkali-free absorbent, we found that the size and shape of the absorbent container was the major factor in determining the efficiency of the carbon dioxide absorbents.     

一氧化碳与炎症的研究进展

一氧化碳具有重要的抗炎作用.一氧化碳释放分子作为CO的一种新的供体,广泛地应用于生物学研究.本文对CO的抗炎作用和CORM的研究进展进行综述.     

二氧化碳吸收剂中水分对七氟醚分解反应的影响

目的　研究模拟紧闭反应器内干燥的二氧化碳 (CO2 )吸收剂及自身含水对七氟醚分解的影响。方法　在紧闭反应器 (1 6 0ml)内 ,分别装钠石灰、钡石灰、干燥钠石灰和干燥钡石灰 (各 2 5g)。在密闭状态下注入液态的七氟醚 4 0 0 μl,放入 5 0℃水浴内反应 6h ,分别在 5、1 5、30、4 5、6 0min、以后每 30分钟至 36 0分钟采样 ,用气相色谱法分析。测定七氟醚的分解产物。结果　钠石灰组出现复合物A、B ,在其他组七氟醚产生 5种分解产物。复合物A∶干燥钡石灰 >干燥钠石灰 >钡石灰和钠石灰组。干燥钡石灰组明显高于其他两组 (P <0 0 5 )。复合物B∶干燥钡石灰组 <钡石灰组 <干燥钠石灰组 (P <0 0 5 )。复合物C、D、E ,以干燥钡石灰组最为明显 (P <0 0 5 )。各组均未检测到CO。结论　在 5 0℃的紧闭反应器内 ,七氟醚与干燥的CO2 吸收剂反应剧烈 ,未产生CO ;国产钠石灰优于钡石灰 ,在紧闭容器内自身含水可以抑制分解反应     

经皮二氧化碳监测在肥胖患者行腹腔镜胃旁路术中的应用

目的研究肥胖患者行腹腔镜下胃旁路术中经皮二氧化碳分压(P_(TC)CO_2)监测评估PaCO_2的准确性和相关性。方法择期行腹腔镜下胃旁路术的患者22例,男9例,女13例,年龄19~55岁,体重86~160kg,BMI35kg/m~2,ASAⅠ或Ⅱ级,在麻醉后(气腹前)和气腹后30、60和120min时测量PaCO_2、P_(ET)CO_2和P_(TC)CO_2。并计算PaCO_2-P_(ET)CO_2和PaCO_2-P_(TC)CO_2的差值,采用Bland-Altman分析、相关与回归和确切概率法分析PaCO_2与P_(ET)CO_2、PaCO_2与P_(TC)CO_2的线性回归方程和一致性界限(LOA)。结果 1例男性患者因麻醉诱导时使用了去氧肾上腺素而被排除出本研究。余患者PaCO_2-P_(ET)CO_2的差值为(10.3±2.3)mm Hg,PaCO_2-P_(TC)CO_2的差值为(0.9±1.3)mm Hg。PaCO_2与P_(ET)CO_2之间的线性回归方程为P_(ET)CO_2=11.58~+0.57×PaCO_2(r2=0.64,P0.01);PaCO_2与P_(TC)CO_2之间的线性回归方程为P_(TC)CO_2=0.60~+0.97×PaCO_2(r2=0.89,P0.01),气腹后30、60和120min时P_(ET)CO_2和P_(TC)CO_2与PaCO_2具有明显相关性(P0.01)。PaCO_2-P_(ET)CO_2差值的95%LOA为(10.3±4.6)mm Hg;PaCO_2-P_(TC)CO_2差值的95%LOA为(0.9±2.6)mm Hg。结论肥胖患者行腹腔镜下胃旁路术中,P_(TC)CO_2比P_(ET)CO_2更精确地评估PaCO_2。     

Inhaled carbon monoxide attenuates myocardial inflammatory cytokine expression in a rat model of cardiopulmonary bypass

Carbon monoxide (CO), a by-product of Heme metabolism, is a potent modulator of inflammation. Low dose inhaled CO has demonstrated reduced lung and kidney injury in animal models of cardiopulmonary bypass (CPB). We evaluated the impact of low dose inhaled CO on systemic, pulmonary, and myocardial inflammatory response to CPB in rats. Sixteen male Sprague-Dawley rats underwent CPB for 1 hour. The CO (n = 8) group received inhaled CO at 250 ppm for 3 hours before CPB. The Air (n = 8) group served as the control. Pulmonary mechanics were assessed pre and post CPB. The animals were recovered for 30 minutes post CPB and subsequently sacrificed. Pre CPB and post CPB serum Tumor Necrosis Factor-alpha (TNF-alpha) and Interleukin-10 (IL-10) were analyzed by enzyme-linked immunosorbent assay. Gene expression array and real time quantitative polymerase chain reaction (PCR) analysis was performed on the extracted heart tissue. Baseline characteristics were similar between the groups with the expected exception of carboxyhemoglobin levels (p < or = .001) and oxyhemoglobin saturation (p < or = .01) in Air versus CO treated groups, respectively. Serum TNF-alpha (363 +/- 278 vs. 287 +/- 195;p = .13) and IL-10 (237 +/- 26 vs. 302 +/- 137; p = Not Significant) in Air versus CO groups respectively were not statistically different after CPB, despite showing a trend of inflammatory attenuation. Gene expression array of the myocardial tissue suggested a pattern of inflammatory modulation, which was confirmed by real time quantitative PCR demonstrating IL-10 expression 3.13 times higher (p = .02) in the CO treated group compared to the Air group. These data demonstrate that pretreatment with CO at 250 ppm may have a modulatory effect on the inflammatory response to CPB without compromising hemodynamics or oxygen delivery. Further investigation in a survival model of CPB is warranted.     

Validation of a model for flow-dependent carbon dioxide exchange in artificial lungs

The exchange rate of CO2 in artificial lungs depends on the sweep gas flow rate. Control of the amount of CO2 removed by an artificial lung requires quantitative knowledge of the flow dependence. A simple model of the dependence of CO2 exchange on sweep gas flow rate in artificial lungs has been previously presented (1). For a given partial pressure of CO2 in the blood phase, sweep gas flow rate, and CO2 exchange rate, the model indicates how close the CO2 exchange rate is to the maximum level attainable by the artificial lung. The focus of this study was to validate the model experimentally by testing 2 commercial artificial lungs in an in vitro test loop. The CO2 exchange rate for each artificial lung was measured over a range of sweep gas flow rates. Linear regression was used to fit the data to the model and estimate the maximum possible CO2 exchange rate and the average water-side PCO2 (PCO2w). The difference between the measured and regressed values of PCO2w was used as an indicator of the ability of the model to quantitatively predict the dependence of CO2 exchange on gas flow rate. This difference was less than 5% for each experiment, indicating that the model can be used to guide control of CO2 exchange rates in artificial lungs.     

Effect of small bowel perforation during laparoscopy on end-tidal carbon dioxide: observation in a small animal model

INTRODUCTION: There are currently no reports in the literature regarding changes in end-tidal carbon dioxide (ETCO(2)) when the small bowel is deliberately or inadvertently perforated during laparoscopic surgery. The aim of this study was to assess the influence of small bowel perforation during laparoscopy on ETCO(2) in a rat model. MATERIALS AND METHODS: Two groups of Wistar rats (n = 8/group) were anesthetized, tracheostomized, and mechanically ventilated at a fixed tidal volume and respiratory rate. After a stabilization phase of 30 min, CO(2) pneumoperitoneum was established to 5 mmHg in one group and 12 mmHg in the other group, and maintained for 30 min. A small bowel perforation was then created and pneumoperitoneum was reestablished for another 30 min. Blood pressure, heart rate, peak ventilatory pressure, and ETCO(2) were recorded throughout the experiment. RESULTS: No significant changes in blood pressure throughout the experiment were noted in either group. The ventilatory pressure increased in both groups after the induction of pneumoperitoneum. In the 5 mmHg group, there was a modest increase in ETCO(2) following the induction of pneumoperitoneum (from 39.4 +/- 1.9 to 41.1 +/- 1.4, P = 0.014), and a further increase following the small bowel perforation (from 41.1 +/- 1.4 to 42 +/- 0.8, P = 0.007). In the 12 mmHg group, there was no change in ETCO(2) after the induction of pneumoperitoneum; however, there was a substantial increase in ETCO(2) following bowel perforation (35.0 +/- 2.0 to 49.8 +/- 7.1, P = 0.002). CONCLUSIONS: ETCO(2) increases when the small bowel is perforated during CO(2) pneumoperitoneum. This increase seems more substantial under higher pneumoperitoneal pressures. Small bowel injury may enable the diffusion of CO(2) through the bowel mucosa, causing ETCO(2) elevation. Therefore, an abrupt increase in ETCO(2) observed during laparoscopy may indicate small bowel injury.     

Carbon monoxide poisoning - a cause of increased QT dispersion

BACKGROUND: Carbon monoxide (CO) poisoning is associated with direct cardiovascular toxicity. QT dispersion (QTd) of the ECG is an indirect measure of heterogeneity of ventricular repolarization, which may contribute to ventricular arrhythmias. Our aim was to study QTd in patients with acute CO poisoning. METHODS: CO intoxication was confirmed by arterial blood gas analysis. A control group consisted of age- and sex-matched individuals admitted to the hospital for unrelated clinical conditions. 12-lead ECG's were recorded on admission and repeated 1 week after discharge from the hospital. QT dispersion was defined as the difference between the greatest and the least QT intervals in any of the 12 leads. RESULTS: Seventeen intoxicated patients, aged 5-46 years, had mean carboxyhemoglobin levels of 22.5 +/- 11.1%. On admission, corrected QT intervals of the intoxicated patients were significantly increased compared to the control group (431 +/- 18 ms vs. 404 +/- 28 ms, P = 0.008), but not the QT interval (358 +/- 25 ms vs. 345 +/- 20 ms, P = 0.17). Mean QTd and cQTd values (46 +/- 15 ms and 62 +/- 13 ms) of the intoxicated patients were significantly increased compared to the control group (17 +/- 4 ms and 33 +/- 15 ms, P < 0.0001 for both). Both QTd and cQTd decreased significantly after discharge from the hospital (P = 0.0001). CONCLUSION: Although QT dispersion increased in patients with CO poisoning, none of ECG's showed ventricular arrhythmia. Increased QTd in the absence of QT interval prolongation may have a lowered arrhythmogenic potential of CO poisoning.     

Transcutaneous carbon dioxide monitoring in infants and children

Objective: To review the technology required for and the applications of transcutaneous carbon dioxide (TC‐CO₂) monitoring in infants and children. Data source: A computerized, bibliographic search regarding the applications of transcutaneous carbon dioxide (TC‐CO₂) monitoring in infants and children. Results: Although the direct measurement of P_aCO₂ remains the gold standard, it provides only a single measurement of what is often a rapidly changing and evolving clinical picture. Given these concerns, there remains a clinical need for a means to continuously monitor P_aCO₂ without the need for repeated blood gas analysis. Although initially introduced into the neonatal intensive care unit; with improvements in the technology, TC‐CO₂ monitoring can now be used in infants, children and even adults. When compared with end‐tidal carbon dioxide (ET‐CO₂) monitoring techniques, TC‐CO₂ monitoring has been shown to be equally as accurate in patients with normal respiratory function and more accurate in patients with shunt or ventilation–perfusion inequalities. TC‐CO₂ monitoring can be applied in situations that generally preclude ET‐CO₂ monitoring such as high frequency ventilation, apnea testing, and noninvasive ventilation. TC‐CO₂ monitoring has also been used in spontaneously breathing children with airway and respiratory issues such as croup and status asthmaticus as well as to monitor metabolic status during treatment of acidosis related to diabetic ketoacidosis. Conclusions: Transcutaneous carbon dioxide monitoring may be a useful adjunct in various clinical scenarios in infants and children. It should be viewed as a complimentary technology and may be used in combination with ET‐CO₂ monitoring.     

患者低流量吸入地氟醚或异氟醚的药代动力学

目的比较腹部手术患者低流量吸入地氟醚或异氟醚的药代动力学。方法腹部手术患者40例,ASAⅠ级或Ⅱ级,年龄18～64岁,BMI＜35kg/m^2。随机分为2组（n=20）：地氟醚组（D组）和异氟醚组（Ⅰ组）。麻醉诱导后调节纯氧流量3L/min,术中调整挥发罐刻度,维持肺泡浓度（FA）0．8 MAC,稳定5min后纯氧流量改为1L/min。调节瑞芬太尼静脉输注速率,维持HR和BP波动幅度不超过基础值20%。手术结束时,停止吸入地氟醚或异氟醚,同时吸入纯氧3L/min。记录设定的吸入麻醉药浓度（FD）、吸入麻醉药浓度（FI）、FA/FI=1/2时间、FA/FAO=1/2时间（FAO为关闭挥发罐即时的肺泡浓度）,并计算各时点FA/FI、FA/FD。结果D组FA/FI=1/2时间及FA/FAO=1/2时间均较Ⅰ组缩短（P＜0．05）。低流量麻醉下,D组FD稳定,Ⅰ组FD波动较大。D组FA/FI、FA/FD上升速率较Ⅰ组快,且同一时点各比值D组均高于Ⅰ组。结论与异氟醚比较,腹部手术患者低流量吸入地氟醚时达到预定的肺泡浓度更迅速,可控性好,停止吸入时排泄较快。     

Relationship between arterial and end-tidal carbon dioxide pressures during anesthesia using a laryngeal tube

BACKGROUND: The Laryngeal Tube (LT), (VBM Medizintechnik, Sulz, Germany) is a relatively new supraglottic device for controlling the airway. Arterial carbon dioxide tension (PaCO(2)) can be estimated by monitoring the end-tidal tension of carbon dioxide (PETCO(2)). The relationship between PETCO(2) and PaCO(2) during controlled ventilation via the LT has not been reported. METHODS: During general anesthesia, 45 patients were mechanically ventilated using an LT. PETCO(2) and PaCO(2) were measured once PETCO(2) had reached a steady state. The LT was then removed and the trachea intubated using an endotracheal tube (ETT), and the identical ventilatory variables were resumed. Following stabilization, PETCO(2) was again determined and PaCO(2) estimated. RESULTS: The mean PETCO(2) and PaCO(2) values were 4.43 +/- 0.26 kPa and 4.67 +/- 0.32 kPa, respectively, during LT ventilation, and 4.36 +/- 0.23 kPa and 4.61 +/- 0.26 kPa, respectively, during ETT ventilation. Analysis of differences between the PETCO(2) and PaCO(2) values using the Bland and Altman method revealed a bias +/- precision of 0.24 +/- 0.15 kPa for LT and 0.27 +/- 0.15 kPa for ETT. The root mean square error was 0.28 for the LT and 0.30 for the ETT. CONCLUSION: This study suggests that for healthy adult patients mechanically ventilated via the LT, the PETCO(2) value reflects the PaCO(2) value as closely as when patients are ETT ventilated, allowing capnometry to be used to evaluate the adequacy of ventilation.     

Carbon dioxide laser therapy of a widespread epidermal nevus

Background and Objective: The treatment of epidermal nevi is difficult and often unsatisfactory. Many therapeutic approaches have been tried, of which the surgical methods including lasers aim to avoid recurrences and hypertrophic scarring. Here we report the case of a widespread, life-impairing epidermal nevus, summarize the available treatment modalities, and discuss CO₂ laser therapy with respect to the clinically soft variants of these developmental defects. Study Design/Patients and Methods: A patient with a widespread, recurrent, biopsy-proven epidermal nevus was treated with a 10,600-nm CO₂ laser. After test treatments in local anaesthesia, four sessions were performed under general anaesthesia each with a follow-up time of 4 years to date. Results: CO₂ laser vaporization resulted in complete removal of the treated nevus without any obvious scarring. The patient is free of recurrence 4 years postoperatively. Conclusion. CO₂ laser treatment of epidermal nevi is a useful modality in selected variants. © 1995 Wiley-Liss, Inc.     

The detection of carbon dioxide embolism during laparoscopy in pigs: a comparison of transesophageal Doppler and end-tidal carbon dioxide monitoring

Background: The aim of the study was to compare the value of transesophageal Doppler and end-tidal carbon dioxide monitoring to detect venous carbon dioxide embolism in pigs during laparoscopic cholecystectomy.
Method: Ten pigs were anesthetized under constant ventilation, and instrumented for laparoscopic cholecystectomy. CO₂ pneumoperitoneum was performed at 15 mmHg and then, successive increased intravenous gas boluses of 0.1 to 4 ml/ kg injectedthrough the femoral vein using a 55-mm long catheter. The responses indicative of embolism were defined as: 1) a change in Doppler tone placed facing the junction of the right atrium and inferior vena cava; 2)
Results: Doppler was more sensitive in detecting 0.1, 0.2 and 0.4 ml/mg of CO₂ embolism than end-tidal CO₂ ( P <0.05). Over 0.4 ml/mg no differences in sensitivity were found but the Doppler signal modifications occurred earlier than the changes in end-tidal CO₂. Moreover, these changes always consisted of a reduction of the value.
Conclusions: During laparoscopic cholecystectomy in pigs, transesophageal Doppler was a highly sensitive monitor which provided an earlier detection of CO₂ embolism and at lower doses than end-tidal CO₂ monitoring.     

Effects of rectal thiopentone and methohexitone on carbon dioxide tension in infant anaesthesia with spontaneous ventilation

The influence of rectal administration of barbiturates on PCO2 during mask anaesthesia with spontaneous ventilation was studied in 72 infants. The age of the patients ranged between 6 and 24 months and they were all subjected to minor paediatric surgery. The patients were divided into four equally large groups: a control group receiving no premedication, a group receiving rectal thiopentone 30 mg X kg-1 and two groups receiving methohexitone either 20 or 30 mg X kg-1. In all patients PCO2 was measured in an arterialized capillary blood sample obtained during stable anaesthesia with oxygen, nitrous oxide and halothane before and after surgery. After rectal induction with barbiturates, the mean PCO2 was significantly higher in the different barbiturate groups than in the control group (P less than 0.05). The mean PCO2 value +/- s.d. in kPa for the control group was 5.6 +/- 0.7, for the group receiving thiopentone 30 mg X kg-1 6.5 +/- 1.6, for the groups receiving methohexitone 20 or 30 mg X kg-1 6.1 +/- 1.2 and 6.3 +/- 1.1, respectively. It is concluded that the combination of rectal induction with barbiturates and mask anaesthesia with oxygen, nitrous oxide and halothane carries an increased risk of hypoventilation in infants under 2 years of age.     

Transcutaneous carbon dioxide application with hydrogel prevents muscle atrophy in a rat sciatic nerve crush model

The acceleration of nerve regeneration remains a clinical challenge. We previously demonstrated that transcutaneous CO₂ application using a novel hydrogel increases the oxygen concentration in local tissue via an “artificial Bohr effect” with the potential to prevent muscle atrophy. In this study, we investigated the effect of transcutaneous CO₂ administration on limb function after peripheral nerve injury in a rat sciatic nerve injury model. In total, 73 Sprague–Dawley rats were divided into a sham group, a control group (crush injury to sciatic nerve and no treatment) or a CO₂ group (crush injury with transcutaneous CO₂ application). CO₂ was administered percutaneously for 20 min five times per week. Scores for the sciatic function index and pinprick test were significantly higher in the CO₂ group than control group. The muscle wet weight ratios of the tibialis anterior and soleus muscles were higher in the CO₂ group than control group. Electrophysiological examination showed that the CO₂ group had higher compound motor action potential amplitudes and shorter distal motor latency than the control group. Histological examination of the soleus muscle sections at postoperative week 2 showed shorter fiber diameter in the control group than in the CO₂ group. The mRNA expression of Atrogin‐1 and MuRF‐1 was lower, mRNA expression of VEGF and myogenin and MyoD was higher in CO₂ group at postoperative week 2 compared to the control group. Clinical significance: Transcutaneous CO₂ application has the therapeutic potential to accelerate the recovery of muscle atrophy in peripheral nerve injury. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1653–1658, 2018.