电阻抗断层成像技术用于呼气末正压滴定的研究进展

适当的呼气末正压（PEEP）是保护性肺通气策略的重要组成部分,PEEP可以保持肺泡开放,减少肺萎陷伤。尽管个体化PEEP已被越来越多的临床医师认可,但最佳的PEEP滴定方法尚存争议。电阻抗断层成像（EIT）是一种无创、无辐射的成像技术,可在床边实时动态评估肺功能,将肺通气过程中的阻抗变化以动态图像呈现,能够反映PEEP调整前后肺内通气及气体分布变化,因此,EIT可用于滴定个体化PEEP。本文简要概括EIT的基本原理及监测指标,阐述临床应用EIT指导下的PEEP（PEEPEIT）滴定方法,旨在加强对EIT的优点和局限性的理解,为优化个体化PEEP的设置提供参考。     

肥胖患者腹腔镜结直肠癌根治术中实时食管压监测下呼气末正压通气对肺通气的影响

目的探讨实时食管压监测指导下设定呼气末正压(positive end expiratory pressure,PEEP)通气参数对肥胖腹腔镜结直肠癌根治术患者的临床价值。方法选择2016年1—12月收治的拟行腹腔镜结直肠癌根治术的肥胖患者90例,男50例,女40例,年龄40~65岁,BMI30kg/m2,ASAⅡ或Ⅲ级,采用随机数字表法将患者随机分为三组:P组、PEEP5组和PEEP10组,设置VT8ml/kg,分别在肺复张后给予个体化PEEP(采用实时食管压监测通过计算呼气末跨肺压=0cmH_2O和吸气末跨肺压=25cmH_2O确定最佳PEEP)、PEEP 5cmH_2O和10cmH_2O。观察气腹建立前(T0)、气腹建立后10min(T1)、气腹后头低40.5°足高位20 min(T2)和气腹结束(T3)时的呼吸力学指标。结果T1—T3时P组Ppeak、SBP明显低于,PaO_2/FiO_2明显高于PEEP5组和PEEP10组(P0.05);T2时P组Pplat、Raw明显低于PEEP5组(P0.05);T2、T3时P组Cst明显高于PEEP5组(P0.05);T1、T2时P组DBP明显低于PEEP5组和PEEP10组(P0.05)。结论实时食管压监测应用于PEEP通气的肥胖腹腔镜结肠癌手术患者,能够有效改善患者呼吸和循环功能。     

个体化呼气末正压通气对肥胖患者腹腔镜胃减容术后肺部并发症的影响

目的 研究个体化呼气末正压（PEEP）通气策略对肥胖患者腹腔镜胃减容术后肺部并发症（PPCs）的影响。
方法 选择行全身麻醉腹腔镜胃减容术的成年肥胖患者40例,男15例,女25例,年龄18～44岁,BMI 35～55 kg/m²,ASA Ⅱ或Ⅲ级。采用随机数字表法分为两组：个体化PEEP组（I组）和固定PEEP组（C组）,每组20例。I组在诱导插管后依据肺动态顺应性（Cdyn）个体化滴定最佳PEEP并维持此PEEP进行术中通气,C组以PEEP 8 cmH2O进行术中通气。记录插管后5 min、气腹后1 h的氧合指数、分流率以及气道峰压、气道平台压、驱动压、Cdyn等呼吸力学参数,记录术中低血压发生情况、输液量、血管活性药用量、机械通气时间和术后住院时间,记录术后第1天、第2天、第3天、第8天PPCs的发生情况以及术后8 d内PPCs累积发生率。
结果 I组PPCs累积发生率明显低于C组 ［13例（65%） vs 19例（95%）, P＜0.05］。气腹后1 h 时I组氧合指数、气道峰压、气道平台压、Cdyn均明显高于C组（P<0.05）,I组驱动压明显低于C组（P<0.05）。两组术中低血压发生率、输液量、去氧肾上腺素用量、机械通气时间和术后住院时间差异无统计学意义。
结论 个体化PEEP能够降低腹腔镜胃减容术患者PPCs发生率,并在不影响血流动力学稳定性的同时降低术中驱动压,改善氧合。     

不同水平呼气末正压对肥胖患者术中氧合指数影响的Meta分析

目的 评估不同水平呼气末正压（PEEP）对肥胖患者术中氧合指数的影响。
方法 检索PubMed、Embase、Cochrane Library、知网和万方数据库，收集高水平（PEEP≥10 cmH₂O）与低水平（PEEP≤5 cmH₂O） PEEP对肥胖患者术中氧合指数和术后肺部并发症影响的随机对照试验（RCT），检索时间为建库至2021年5月。主要指标为术中氧合指数，次要指标为术后肺部并发症。根据纳入和排除标准进行文献筛选、数据提取和质量评价，采用RevMan 5.4软件进行Meta分析。
结果 共纳入11篇发表于2004—2020年的RCT研究，共纳入患者2 522例，其中高PEEP组1 209例，低PEEP组1 313例。Meta分析显示，与低PEEP组比较，高PEEP组术中氧合指数明显升高（MD=74.21 mmHg，95%CI 46.98~101.43 mmHg, P<0.001），两组术后肺部并发症发生率差异无统计学意义（RR=0.87， 95%CI 0.74～1.02， P=0.09）。
结论 全麻期间采用PEEP≥10 cmH₂O可以改善肥胖患者术中氧合指数，对肺功能具有一定的保护作用，但是不能降低肥胖患者术后肺部并发症的发生率。     

呼气末正压通气对腹腔镜宫颈癌根治术患者眼压和视神经鞘直径的影响

目的观察腹腔镜下宫颈癌根治术中,5 cmH_2O的呼气末正压通气(PEEP)对患者眼内压(IOP)和颅内压的影响。方法选择我院择期行腹腔镜下宫颈癌根治术的患者60例,年龄45～65岁,BMI 20～25 kg/m~2,ASAⅠ或Ⅱ级。采用随机数字表法分为两组,PEEP为5 cmH_2O组(PEEP组)和无PEEP组(ZEEP组),每组30例。两组均采用静脉麻醉诱导气管插管,诱导完成机械通气后,PEEP组设置呼气末正压为5 cmH_2O,ZEEP组呼气末正压设置为0。记录麻醉诱导前(T_0)、麻醉后气腹前10 min平卧位(T_1)、气腹Trendelenburg体位后5 min(T_2)、30 min(T_3)、恢复平卧位气腹消失后(T_4)和术后30 min(T_5)时的IOP、视神经鞘直径(ONSD)、PaO_2、PaCO_2,同时记录T_1—T_4时肺动态顺应性(Cdyn)、气道峰压(Ppeek)和T_0—T_5时HR和MAP。结果与T_0时比较,T_1时两组IOP明显降低(P0.01),T_2—T_3时IOP明显延长(P0.01),T_2—T_3时ZEEP组ONSD明显延长(P0.01),T_3时PEEP组ONSD明显延长(P0.05)。T_1—T_4时PEEP组PaO_2、Cdyn明显高于ZEEP组(P0.05)。T_1时PEEP组Ppeek明显高于ZEEP组(P0.05)。结论在腹腔镜宫颈癌根治术手术中,气腹和Trendelenburg体位下应用5 cmH_2O的PEEP改善患者氧合的同时不引起IOP和颅内压的增高。     

Endocrine responses to positive end-expiratory pressure ventilation in patients who have recently undergone heart surgery

The effect of positive end-expiratory pressure ventilation (PEEP) on angiotensin II and atrial natriuretic factor (ANF) was studied postoperatively following heart surgery. In nine patients pressures were recorded in the radial artery, pulmonary artery and the right atrium. PEEP of 5 cmH2O (0.5 kPa) and 10 cmH2O (1 kPa) increased angiotensin II from 38.8 +/- 20.3 (mean +/- s.e.mean) to 56.7 +/- 29.6 (n.s.) and 66.7 +/- 28.7 (P less than 0.05) pmol/l, respectively. Plasma-ANF showed no significant changes during PEEP. Pulmonary artery wedge pressure increased from 12.9 +/- 2.0 to 14.1 +/- 2.0 (n.s.) and 18.5 +/- 2.1 (P less than 0.01) mmHg, and right atrial pressure from 8.3 +/- 1.7 to 9.8 +/- 1.7 (n.s.) and 12.9 +/- 1.7 (P less than 0.01) mmHg with 5 and 10 cmH2O (0.5 and 1.0 kPa) of PEEP, respectively. Systemic blood pressure tended to decrease (n.s.) with PEEP. In conclusion, PEEP markedly increased angiotensin II. This may represent an important compensatory mechanism, helping to prevent reduction in aortic pressure during PEEP. ANF, however, did not change with PEEP of 5 or 10 cmH2O (0.5 and 1.0 kPa).     

肺动态顺应性指导个体化呼气末正压通气对老年患者腹腔镜结直肠癌术中肺功能的影响

目的 观察肺动态顺应性（Cdyn）指导个体化呼气末正压通气（PEEP）对老年患者腹腔镜结直肠癌术中肺功能的影响。
方法选择择期行腹腔镜结直肠癌根治术的老年患者68例，男37例，女31例，年龄65～79岁，BMI<30 kg/m²，ASA Ⅱ或Ⅲ级。采用随机数字表法将患者分为两组：个体化PEEP组（P组）和对照组（C组），每组34例。P组在插管完成即刻、气腹-屈氏体位建立即刻、气腹结束即刻行肺复张及PEEP滴定试验，C组设置固定PEEP 5 cmH₂O。记录P组3次滴定时最佳PEEP和实际V_T。记录气管插管完成后10 min（T₁）、气腹-屈氏体位建立后10 min（T₂）、60 min（T₃）、手术结束拔管前（T₄）PaO₂、PaCO₂、P_ETCO₂，计算氧合指数（OI）、死腔/潮气量比值（Vd/V_T）、肺泡-动脉血氧分压差（A-aDO₂）、驱动压和Cdyn。采用ELISA法测定麻醉诱导前（T₀）、拔管后10 min（T₅）的白细胞介素-8（IL-8）、肿瘤坏死因子-α（TNF-α）、肺Clara细胞分泌蛋白（CC16）及肺泡表面活性物质-D（SP-D）的浓度。记录术后肺部并发症（PPCs）的发生情况。
结果 P组滴定最佳PEEP的中位数为4 cmH₂O。与C组比较，P组T₄时PaO₂、OI明显升高，T₁、T₃、T₄时Cdyn明显升高，T₁—T₄时驱动压明显降低，T₅时CC16血清浓度明显降低（P<0.05）。两组T₁—T₄时PaCO₂、P_ETCO₂、A-aDO₂、Vd/V_T差异无统计学意义。两组术后3 d均未发生严重PPCs。
结论 在老年患者腹腔镜结直肠癌根治术中，采用压力控制通气下肺动态顺应性指导个体化PEEP的肺保护通气策略，可提高患者术中肺动态顺应性，降低驱动压，改善手术结束时氧合，降低术后CC16血清浓度，改善术中肺功能。     

个体化呼气末正压对心肺转流下瓣膜手术患者肺功能的影响

目的探讨心脏瓣膜术中早期应用个体化呼气末正压(PEEP)对患者肺功能的影响。方法选择2019年7—10月择期行瓣膜手术的患者33例,男11例,女22例,年龄40～70岁,BMI 18～26 kg/m~2,ASAⅡ或Ⅲ级,心功能Ⅱ或Ⅲ级。采用随机数字表法将患者分为两组:对照组(C组,n=17)和个体化PEEP组(P组,n=16),两组术中麻醉维持为全凭静脉麻醉。停机后P组采用阶梯PEEP法滴定适宜的PEEP,并维持至手术结束,C组设置固定PEEP 4 cmH_2O。记录手术前(T_0)、肺复张前(T_1)、肺复张后40 min(T_2)、术后2 h(T_3)、术后24 h(T_4)的氧合指数(PaO_2/FiO_2),T_0—T_2时的HR、MAP、CVP,T_1—T_3时的肺动态顺应性(Cdyn)。使用经胸超声检查并记录T_0、T_2—T_4时的肺超声评分(LUS评分)和术后肺部并发症的发生情况。结果与T_1时比较,T_2、T_3时P组PaO_2/FiO_2和Cdyn明显升高(P0.05)。与C组比较,T_2时P组PaO_2/FiO_2和Cdyn均明显升高(P0.05),T_2—T_4时P组LUS评分明显降低(P0.05),P组术后肺水肿的发生率明显降低(P0.05)。两组其余术后肺部并发症发生率差异无统计学意义。结论在心脏瓣膜手术心肺转流停机后早期应用个体化PEEP具有肺保护作用。     

Electrical impedance tomography: changes in distribution of pulmonary ventilation during laparoscopic surgery in a porcine model

Background

Because of the creation of a pneumoperitoneum, impairment of ventilation is a common side-effect during laparoscopic surgery. Electrical impedance tomography (EIT) is a method with the potential for becoming a tool to quantify these alterations during surgery. We have studied the change of regional ventilation during and after laparoscopic surgery with EIT and compared the diagnostic findings with computed tomography (CT) scans in a porcine study.

Materials and methods

After approval by the local animal ethics committee, six pigs were included in the study. Two laparoscopic operations were performed [colon resection (n=3) and fundoplicatio (n=3)]. The EIT measurements (6th parasternal intercostal space) were continuously recorded by an EIT prototype (EIT Evaluation Kit, Dräger Medical, Lübeck, Germany). To verify ventilatory alterations detected by EIT, a CT scan was performed postoperatively.

Results

Ventilation with defined tidal volumes was significantly correlated to EIT measurements (r ²=0.99). After creation of the pneumoperitoneum, lung compliance typically decreased, which agreed well with an alteration of the distribution of pulmonary ventilation measured by EIT. Elevation of positive end-inspiratory pressure reopened non-aerated lung areas and showed a recovery of the regional ventilation measured by EIT. Additionally, we could detect pulmonary complications by EIT monitoring as verified by CT scans postoperatively.

Conclusion

EIT monitoring can be used as a continuous non-invasive intraoperative monitor of ventilation to detect regional changes of ventilation and pulmonary complications during laparoscopic surgery. These EIT findings indicate that surgeons and anesthetists may eventually be able to optimize ventilation directly in the operating theatre.     

吸入氧浓度及呼气末正压对妇科腹腔镜手术患者动脉血-呼气末二氧化碳分压差的影响

目的 评价吸入氧浓度(FiO2)及呼气末正压(PEEP)对妇科腹腔镜手术患者动脉血-呼气末二氧化碳分压差[D(a-ET) CO2]的影响.方法 择期全麻下妇科腹腔镜手术患者60例,年龄25～50岁,体重45～75 kg,体重指数＜30 kg/m2,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将其分为3组(n=20):A组纯氧机械通气,PEEP为0；B组空氧混合气体机械通气,FiO2 50％,PEEP为0；C组空氧混合气体机械通气,FiO2 50％,PEEP为5 cm H2O.机械通气中监测PE,CO2,于气管插管后即刻(T1)和气腹1 h(T2)时取桡动脉血行血气分析,计算D(a-ET) CO2及肺内分流率(Qs/Qt).结果 与A组比较,B组和C组T2时D(a-ET) CO2及Qs/Qt降低(P＜0.05)；与B组比较,C组T2时D(a-ET) CO2降低(P＜0.05),Qs/Qt差异无统计学意义(P＞0.05).结论 降低FiO2及给予PEEP 5 cm H2O可降低妇科腹腔镜手术患者D(a-ET) CO2,提高pETCO2反映PaCO2的准确性,其原因与减少肺内分流有关.     

Regional pulmonary pressure volume curves in mechanically ventilated patients with acute respiratory failure measured by electrical impedance tomography

BACKGROUND: We hypothesized, that in mechanically ventilated patients with acute respiratory failure, regional pressure volume curves differ markedly from conventional global pressure volume curves of the whole lung. METHODS: In nine mechanically ventilated patients with acute respiratory failure during an inspiratory low-flow manoeuvre, conventional global pressure volume curves were registered by spirometry and regional pressure volume curves in up to 912 regions were assessed simultaneously using electrical impedance tomography. We compared the lower (LIP) and upper (UIP) inflection points obtained from the conventional global pressure volume curve and regional pressure volume curves. RESULTS: We identified from the conventional global pressure volume curves LIP [3-11 (8) cmH2O] in eight patients and UIP [31-39 (33) cmH2O] in three patients. Using electrical impedance tomography (EIT), LIP [3-18 (8) cmH2O] in 54-264 (180) regions and UIP [23-42 (36) cmH2O] in 149-324 (193) regions (range and median) were identified. Lung mechanics measured by conventional global pressure volume curves are similar to the median of regional pressure volume curves obtained by EIT within the tomographic plane. However, single regional pressure volume curves differ markedly with a broad heterogeneity of lower and upper inflection points. CONCLUSION: Lower and upper inflection points obtained from conventional global pressure volume curves are not representative of all regions of the lungs.     

Level of agreement between cardiac output measurements using Nexfin® and thermodilution in morbidly obese patients undergoing laparoscopic surgery

Morbidly obese patients are at increased risk of intra‐operative haemodynamic instability, which may necessitate intensive monitoring. Non‐invasive monitoring is increasingly used to measure cardiac output; however, it is unknown whether the weight‐based algorithm utilised in these devices is applicable to patients with morbid obesity. We compared the level of agreement and trending ability of non‐invasive cardiac output measurements (Nexfin^®) with the gold‐standard thermodilution technique in 30 morbidly obese patients undergoing laparoscopic surgery. Bland–Altman analysis revealed a mean (SD) bias of 0.60 (1.62) l.min^?1 (limits of agreement ?2.67 to 3.86 l.min^?1) and the precision error was 46%. Polar plot analysis resulted in an angular bias of 2.61°, radial limits of agreement of ?60.08° to 49.82° and angular concordance rate was 77%. Both agreement and trending were outside the Critchley criteria for the comparison of cardiac output devices with a gold‐standard. Nexfin has an unacceptable level of agreement compared with thermodilution for cardiac output measurement in morbidly obese patients.     

A prospective trial for laparoscopic adjustable gastric banding in morbidly obese adolescents: an interim report of weight loss, metabolic and quality of life outcomes

Background and Materials and Methods

The outcome of patients completing 12 months of follow-up in a prospective longitudinal trial of the safety/efficacy of laparoscopic adjustable gastric banding (LAGB) for morbidly obese adolescents aged 14 to 17 years using a Food and Drug Administration Institutional Device Exemption for the use of the LAPBAND was analyzed. Baseline and outcome data were abstracted from a prospective database.

Results

Baseline (mean ± SD) body mass index was 50 ± 10 kg/m², and excess weight was 178 ± 53 lb in 20 patients. Comorbidities included hypertension (45%), dyslipidemia (80%), insulin resistance (90%), metabolic syndrome (95%), and biopsy-proven nonalcoholic steatohepatitis (88%). At mean (SD) follow-up of 26 (9) months, % excess weight loss was 34% ± 22% (n = 20) and 41% ± 27% (n = 12), and the metabolic syndrome was resolved in 63% and 82% of the patients at 12 and 18 months, respectively. Hypertension normalized in all patients, along with improvement in lipid abnormalities and quality of life scores (P < .05). At 12 months, of the 5 patients with less than 20% excess weight loss, dyslipidemia and metabolic syndrome were resolved in 2 patients.

Conclusion

At intermediate follow-up of a LAGB-based obesity treatment program, weight loss led to resolution or improvement of major obesity-related comorbidities in most patients, supporting the efficacy of LAGB as a surgical adjunct to a comprehensive obesity treatment program and its long-term evaluation.     

Bilevel positive airway pressure for gastroscopy with sedation in patients at risk of hypoxemia: A prospective randomized controlled study

Study objectiveHypoxemia is one of the most frequent adverse events during sedated gastroscopy, and there is still no effective means to prevent and cure it. Therefore, we conducted this randomized trial to confirm our hypothesis that, compared with the nasal cannula group, bilevel positive airway pressure (BPAP) would decrease the incidence of hypoxemia in patients with obstructive sleep apnea (OSA) or overweight status undergoing gastroscopy.DesignIn a single-center, prospective, randomized controlled clinical trial, 80 patients aged 18–65 years and with OSA or overweight status who underwent gastroscopy with sedation were randomly assigned to two groups: the nasal cannula and BPAP groups. The primary outcome was the incidence of hypoxemia (75% < peripheral oxygen saturation [SpO2] < 90% for >5 sand <60 s).Main resultsCompared to the nasal cannula group, BPAP therapy significantly decreased the incidence of hypoxemia from 40.0% to 2.5% (absolute risk difference [ARD], 37.5% [95% confidence interval (CI), 21.6 to 53.4], p < 0.001), decreased subclinical respiratory depression from 52.5% to 22.5% (ARD, 30.0% [95% CI, 9.8 to 50.2], p = 0.006), and decreased severe hypoxemia from 17.5% to 0% (ARD, 17.5% [95% CI, 5.7 to 29.3], p = 0.006). The BPAP intervention also decreased the total propofol dosage and operation time and improved anesthesiologist's satisfaction.ConclusionBPAP therapy significantly decreased the incidence of hypoxemia in patients with OSA or overweight status who underwent gastroscopy.