End tidal carbon dioxide monitoring in spontaneously breathing, nonintubated patients. A clinical comparison between conventional sidestream and microstream capnometers

BACKGROUND: To evaluate the end tidal carbon dioxide estimation in nonintubated, spontaneously breathing patients using either conventional sidestream or microstream capnometers. METHODS: Patients received a regional anesthesia technique, while the end tidal carbon dioxide partial pressure (EtCO2) was sampled through a nasal cannula (Nasal FilterLine, Nellcor, Plesanton, CA, USA) and measured using either a conventional sidestream capnometer with a 200 ml.min-1 aspiration flow rate, or a microstream capnometer (NBP-75, Nellcor Puritan Bennett, Plesanton, CA, USA) with an aspiration flow rate of 30 ml.min-1. After a 20 min period with stable hemodynamic variables (systolic arterial blood pressure within +/- 20% from baseline values), the EtCO2 was randomly recorded using one of the two capnometer while arterial blood was simultaneously drawn from the radial artery and analyzed for measurement of arterial CO2 partial pressure. Afterwards the nasal cannula was connected to the other capnometer and the procedure repeated. Both the capnometer and arterial blood gas analyzer were calibrated before each studied patient according to the manufacturer instructions. The same procedure was repeated at least two times in each patient. RESULTS: A total of 120 pairs of EtCO2 and PaCO2 measurements were drawn from 30 adults (age: 69 +/- 5 years; weight: 70 +/- 10 kg; height: 160 +/- 10 cm): 60 using the conventional sidestream capnometer and 60 with the microstream one. The median arterial to end tidal CO2 tension difference was 4.4 mmHg (range: 0.28 mmHg) with the microstream capnometer and 7 mm Hg (range: 0-22 mmHg) with the conventional capnometer (p = 0.02). CONCLUSION: The microstream capnometer provides a more accurate end tidal CO2 partial pressure measurement in nonintubated, spontaneously breathing patients than conventional sidestream capnometers, allowing for adequate monitoring of the respiratory function in nonintubated patients.     

Evaluation of a transportable capnometer for monitoring end-tidal carbon dioxide

We compared a small and transportable Capnometer (EMMA?) with a reference capnometer, the Siesta i TS Anaesthesia. During air‐breathing through a facemask, both the EMMA (nine modules) and reference capnometer sampled expired gas simultaneously. A wide range of end‐tidal carbon dioxide values were obtained during inhalation of carbon dioxide and voluntary hyperventilation. The median IQR [range] difference between all sets of carbon dioxide values (EMMA – reference) was ?0.3 (?0.6 to 0.0 [?1.7 to 1.6] kPa; n = 297) using new batteries, which was statistically significant (p = 0.04) and located to two of the nine EMMAs tested. Using batteries with reduced voltage did not influence the measurements. The 95% CI of the medians of the differences were ?0.4 to ?0.2. We conclude that the EMMA can slightly under‐read the end‐tidal carbon dioxide but is generally comparable with a free‐standing monitor. The precision of the EMMAs was similar whether new batteries or batteries with reduced voltage were used.     

Accuracy of end-tidal PCO2 measurements using a sidestream capnometer in infants and children ventilated with the Sechrist infant ventilator

To determine the accuracy of end-tidal PCO2 (PETCO2) measurements analyzed with a sidestream capnometer in infants and children whose lungs were ventilated with a Sechrist infant ventilator and an Ayre's t-piece, we compared PETCO2 measurements obtained from the proximal (PETCO2-p) and distal (PETCO2-d) ends of the tracheal tube to arterial PCO2 (PaCO2) in 37 healthy infants and children between 1.3 and 24.5 kg. Both PETCO2-p and PETCO2-d accurately approximated PaCO2, however, the mean (+/- SD) arterial to end-tidal PCO2 difference (delta(a-ET)PCO2) was significantly greater with proximal (1.27 +/- 1.54 mmHg) than with distal sampling (0.64 +/- 1.64 mmHg) (P less than 0.01). In the subgroup of patients who weighted less than 12 kg, the delta(a-ET)PCO2 using proximal gas sampling (1.94 +/- 1.29 mmHg) was also significantly greater than it was using distal sampling (0.74 +/- 1.31 mmHg) (P less than 0.001). We conclude that although statistically different, both proximal and distal estimates of PETCO2 provide acceptable estimates of PaCO2 in healthy infants and children who are ventilated with a Sechrist infant ventilator and an Ayre's t-piece system.     

呼末二氧化碳分压监测在后腹腔镜手术中的作用

目的 探讨呼末二氧化碳分压(PETCO2)监测在后腹腔镜手术中的作用.方法 回顾分析72例择期行后腹腔镜手术的患者,依据PaCO2监测结果将患者分为两组,A组:各监测时点PaCO2＜60 mmHg;B组:气腹后至少有一个时间点PaCO2＞60 mmHg.分别于气腹前(T1)、气腹后30 min(T2)、60 min (T3)、90 min (T4)时记录各时间点的PaCO2、PETCO2,根据PETCO2及PaCO2计算每个时间点的Pa-ETCO2.结果 两组间比较:T1、T2时间点B组患者的PaCO2、PETCO2、Pa-ETCO2较A组无统计学差异(P＞0.05),T3、T4时间点B组患者的三项监测指标较A组有统计学差异(P＜0.05).两组组内比较:A组,T2-4与T1相比较,PaCO2、PETCO2、Pa-ETCO2均有统计学差异(P＜0.05),T3与T2、T4与T3、T4与T2比较三项监测指标均无统计学差异(P＞0.05):B组,T2-4与T1相比较,PaCO2、PETCO2、Pa-ETCO2均有统计学差异(P＜0.05或P＜0.01),随着气腹时间的延长,PaCO2、PETCO2两项监测指标均逐渐升高,T3与T2、T4与T3、T4与T2比较PaCO2有统计学差异(P＜0.05),PETCO2 T4与T2比较有统计学差异(P＜0.05).结论 后腹腔镜手术气腹后患者的PaCO2、PETCO2、Pa-ETCO2均会升高,尤其是体重指数＞30 kg/m2、术前肺功能检查轻至中度阻塞性通气障碍、术中发生皮下气肿的患者,PaCO2、PETCO2随时间的延长而呈进行性升高,单靠PETCO2监测不能完全满足对患者的监测需要,术中应该辅以动脉血气分析监测PaCO2.     

Directed manual recruitment of collapsed lung in intubated and nonintubated patients

Four patients with collapsed lung are presented that demonstrate the utility of the directed manual recruitment technique (DMRT) in a range of clinical situations presented by weaning difficulties, recurrent acute atelectasis, and acute respiratory failure in the nonintubated patient. DMRT is an easily applied noninvasive method of lung expansion in the treatment of patients with segmental and lobar collapse and is safe when carried out with appropriate precautions.     

呼气末二氧化碳分压反映患儿置入喉罩机械通气时动脉血二氧化碳分压的准确性

目的 评价PETCO2反映患儿置入喉罩机械通气时PaCO2的准确性.方法 拟在全身麻醉下行骨科手术患儿52例,ASA分级Ⅰ级,年龄2～9岁,体重10～30 kg.采用分层随机法,将患儿随机分为2组(n=26):喉罩组(LMA组)和气管导管组(ETT组).常规麻醉诱导后行机械通气,待血液动力学稳定后,采集桡动脉血样测定PaCO2,同时记录PETCO2.结果 两组间PETCO2和PaCO2比较差异无统计学意义(P＞0.05);LMA组PETCO2与PaCO2比较差异无统计学意义(P＞0.05).结论 患儿置入喉罩机械通气时,PETCO2可反映PaCO2,用于指导调整机械通气参数.

Abstract：

Objective To investigate the accuracy of end-tidal carbon dioxide (PETCO2) in reflecting arterial carbon dioxide (PaCO2) during mechanical ventilation via laryngeal mask airway (LMA) in children. Methods Fifty-two ASA Ⅰ patients, aged 2-9 yr, weighing 10-30 kg, undergoing orthopaedic surgery under general anesthesia, were randomized into 2 groups (n = 26 each) : LMA group and endotracheal tube (ETT) group. After anesthesia was induced with fentanyl, propofol and succinycholine, LMA or ETT was inserted and the children were mechanically ventilated. After the hemodynamics was stable, arterial blood samples were obtained to detect PaCO2, and PETCO2 was recorded simultaneously. Results There was no significant difference in PaCO2 and PCT CO, between groups LMA and ETT ( P ＞ 0.05) . There was no significant difference between PaCO2 and PETCO2 in LMA group (P ＞ 0.05). Conclusion When mechanical ventilation is performed via LMA in children, PETCO2 can reliably reflect PaCO2 and guide the regulation of ventilatory parameters.     

盲探气管插管装置联合呼气末二氧化碳监测用于困难气道患者经鼻气管插管的效果

目的 评价盲探气管插管装置联合呼气末二氧化碳监测用于困难气道患者经鼻气管插管的效果.方法 择期经鼻气管插管的口腔颌面外科手术患者60例,性别不限,年龄35-64岁,体重55-75 kg,ASA分级Ⅰ或Ⅱ级,张口度＜3 cm,颈部后仰度＜30°,Mallampati分级Ⅲ或Ⅳ级,甲颏间 距＜6.5 cm,预计为困难气道.采用随机数字表法,将患者随机分为2组(n=30):盲探气管插管装置组(Ⅰ组)和盲探气管插管装置联合呼气末二氧化碳监测(Ⅱ组).Ⅰ组采用盲探气管插管装置进行气管插管;Ⅱ组采用肓探气管插管装置结合呼气末二氧化碳监测进行气管插管.记录气管插管情况、气管插管时间、气管插管期间(鼻衄、心动过速、高血压和低氧血症)和术后(咽痛和声音嘶哑)不良反应的发生情况.结果 2组患者气管插管成功率均为100％.2组均未见心动过速、高血压、低氧血症和声音嘶哑的发生.与Ⅰ组比较,Ⅱ组首次气管插管成功率升高,气管插管时间缩短,鼻衄和咽痛的发生率降低(P＜0.05).结论 盲探气管插管装置联合呼气末二氧化碳监测用于困难气道患者经鼻气管插管时可缩短气管插管时间,提高气管插管成功率,减少不良反应的发生.     

老年人单肺通气时呼气末二氧化碳监测的可信度

目的 观察老年人单肺通气(OLV)麻醉时P_(ET)CO_2C_2和PaCO_2的相关性,以评定P_(ET)CO_2监测在老年人单肺通气麻醉的可信度.方法 37例老年肺部肿瘤患者,胸腔镜下行胸部肿瘤切除、活检或肿瘤根治术,采用静脉复合全麻,术中行OLV.记录麻醉前及OLV 30、60、90、120、180和240min时BP、HR、SpO_2、P_(ET)CO_2和动脉血气,计算氧合指数(PaO_2/FiO_2)、动脉-呼气末二氧化碳分压差(P_(a-ET)CO_2),及对应时间点P_(ET)CO_2和PaCO_2的相关性.结果 除OLV 180 min时点外,术中各时点PaCO_2与P_(ET)CO_2有较好的相关性.术中5例发生低氧血症.结论 老年人OLV麻醉中P_(ET)CO_2不能完全反映PaCO_2的变化,长时间OLV者需同时行血气分析,以保证老年人的安全.     

呼气末二氧化碳分压监测用于心肺复苏及预后评估研究

目的 探讨呼气末二氧化碳分压（PETCO2）监测在急诊科心肺复苏质量及预后评估中的价值，为临床终止CPR提供参考。方法 将急诊科收治的62例心脏骤停患者，根据复苏结果分为自主循环恢复组（ROSC组）32例和非自主循环恢复组（非ROSC组）30例，比较两组患者的一般资料及不同时间节点PETCO2。根据复苏后7 d、28 d生存情况将自主循环恢复者分为生存组和死亡组，比较两组不同时间节点PETCO2。绘制ROC曲线，根据约登指数得出预测ROSC、7 d及28 d生存率的最佳截断值。结果 ROSC组和非ROSC组发病地点、CPR持续时间、肾上腺素及5%碳酸氢钠累计使用剂量差异有统计学意义（均P<0.05）；两组在心肺复苏10 min及之后各个时间节点的PETCO2值差异有统计学意义（均P<0.05）；复苏30 min以内，20 min时PETCO2预测ROSC的曲线下面积最大（AUC=0.982， 95%CI：0.955~1.000），PETCO2最佳截断值为16.5 mmHg，敏感度和特异度分别为93.8%和96.7%，约登指数0.904。ROSC后7 d生存组与死亡组在ROSC时、心肺复苏15 min及之后各时间节点的PETCO2差异有统计学意义（均P<0.05）；心肺复苏20 min时PETCO2值预测ROSC后7 d生存率的曲线下面积最大（AUC=0.882, 95%CI：0.739~1.000），最佳截断值为30 mmHg，敏感度和特异度均为83.3%，约登指数0.667；ROSC后28 d生存组与死亡组在ROSC时、心肺复苏10 min及之后的各时间节点的PETCO2差异有统计学意义（均P<0.05），心肺复苏50 min时PETCO2值预测ROSC后28 d生存的曲线下面积最大（AUC=0.893，95%CI：0.764~1.000），最佳截断值为27.5 mmHg，其敏感度和特异度分别为100%和73.3%，约登指数0.733。结论 呼气末PETCO2能够指导急诊护理人员评价心脏骤停患者心肺复苏质量，并可作为预测患者临床结局的重要指标。     

呼气末二氧化碳分压监测用于心肺复苏及预后评估研究

目的 探讨呼气末二氧化碳分压(P_ETCO₂)监测在急诊科心肺复苏质量及预后评估中的价值,为临床终止CPR提供参考。方法 将急诊科收治的62例心脏骤停患者,根据复苏结果分为自主循环恢复组(ROSC组)32例和非自主循环恢复组(非ROSC组)30例,比较两组患者的一般资料及不同时间节点P_ETCO₂。根据复苏后7 d、28 d生存情况将自主循环恢复者分为生存组和死亡组,比较两组不同时间节点P_ETCO₂。绘制ROC曲线,根据约登指数得出预测ROSC、7 d及28 d生存率的最佳截断值。结果 ROSC组和非ROSC组发病地点、CPR持续时间、肾上腺素及5%碳酸氢钠累计使用剂量差异有统计学意义(均P<0.05);两组在心肺复苏10 min及之后各个时间节点的P_ETCO₂值差异有统计学意义(均P<0.05);复苏30 min以内,20 min时P_ETCO₂预测ROSC的曲...     

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.     

呼气末二氧化碳分压监测在全麻拔管后苏醒期患者中的应用

目的 探讨呼气末二氧化碳分压监测在全身麻醉拔管后苏醒期患者中的应用效果。方法 选取全身麻醉手术结束拔除气管导管转入麻醉后苏醒室观察的320例患者为研究对象,采用随机数字表法分为对照组和观察组各160例。对照组常规单孔鼻导管吸氧3 L/min并持续监测心电图、呼吸、无创血压、血氧饱和度;观察组在对照组基础上持续监测呼气末二氧化碳分压数值和波形的变化并及时给予护理干预。比较两组低氧血症发生情况、高碳酸血症和呼吸暂停检出率、面罩加压给氧率和苏醒时间。结果 观察组低氧血症程度、面罩加压给氧率显著低于对照组,高碳酸血症、呼吸暂停检出率显著高于对照组,苏醒时间显著短于对照组(P<0.05,P<0.01)。结论 对麻醉后苏醒期拔除气管插管的患者,呼气末二氧化碳分压监测可及时发现呼吸暂停、高碳酸血症等呼吸异常事件,降低低氧血症的发生率,提高麻醉苏醒的安全性,缩短苏醒时间。     

Efficacy of the FEF colorimetric end-tidal carbon dioxide detector in children.

Direct laryngoscopy and observation of endotracheal tube (ETT) passage between the vocal cords remain the criterion standard for verifying endotracheal intubation. Detection of end-tidal carbon dioxide (ETCO2) serves as an invaluable adjunct to confirm endotracheal intubation, detect inadvertent esophageal intubation, and monitor for accidental tracheal extubation. Capnography, however, is often unavailable outside the operating suite. A commercially available, disposable, colorimetric ETCO2 detector (FEF, Fenem, Inc., New York, N.Y.), in which color changes using a numerical scale semiquantitatively measure percent carbon dioxide in exhaled gases, has proved effective in confirming endotracheal intubation in adults, but has not been thoroughly investigated in children. We studied 20 otherwise healthy children, aged 6 mo to 8 yr, with simultaneous infrared and colorimetric ETCO2 measurements during elective general anesthesia to evaluate the efficacy of the colorimetric detector. Two hundred of 200 tracheally intubated positive-pressure breaths and 198 of 200 breaths under spontaneous mask ventilation demonstrated a yellow color change (color level 5 or 6), signifying an ETCO2 greater than or equal to 15 mm Hg (2.0 kPa). Repeated-measures analysis of variance revealed no significant differences in infrared ETCO2 values between the two yellow color levels throughout the study period. The associations among color level, infrared ETCO2 determinations, ETT size, and ETT "leak" pressures estimated by Spearman rank correlation analysis were significant only for higher infrared ETCO2 values with higher ETT leak pressures (P less than 0.05). No complications were observed. The Fenem disposable colorimetric ETCO2 detector effectively confirms clinical signs of endotracheal intubation in children when capnography is unavailable.(ABSTRACT TRUNCATED AT 250 WORDS)