二氧化碳结合力水平对接受急诊PCI治疗的急性ST段抬高型心肌梗死患者预后的影响

目的探讨二氧化碳结合力(carbon dioxide combining power,CO_2-CP)水平对急性ST段抬高型心肌梗死(ST segment elevation myocardial infarction,STEMI)患者急诊经皮冠状动脉介入(percutaneous coronary intervention,PCI)治疗后预后的影响。方法选择2011年1月至2018年12月在中国医学科学院阜外医院深圳医院行急诊PCI治疗的775例STEMI患者为研究对象。根据PCI治疗后CO_2-CP水平将其分为低CO_2-CP组(CO_2-CP22 mmol/L,n=180)、高CO_2-CP组(CO_2-CP≥22 mmol/L,n=595)。比较两组之间的基线资料、住院期间主要临床不良事件发生情况和院内死亡情况,并随访1年,记录死亡情况。采用Logistic回归分析对相关因素进行分析。采用Kaplan-Meier曲线分析评估1年累计病死率,并采用log-rank检验进行比较。结果共有51例患者死亡,其中,低CO_2-CP组患者院内病死率和主要临床不良事件发生率均显著高于高CO_2-CP组,差异有统计学意义(P0.05)。Logistic回归分析显示,CO_2-CP22 mmol/L是STEMI患者院内死亡的独立危险因素,且CO_2-CP22 mmol/L患者的1年累计病死率更高(log-rank=21.54,P0.001)。结论 CO_2-CP22 mmol/L的STEMI患者急诊PCI治疗后预后不良。     

平静呼气末二氧化碳分压的测定及临床应用

平静呼气末 CO_2分压(P_(ET)CO_2)是一种有效的非创伤性检查,用以监测肺通气功能。现对P_(ET)CO_2的测定方法及其在机械通气、心肺疾病与外科疾病等方面的应用作一扼要综述。     

慢性阻塞性肺病急性发作期较高浓度给氧对呼吸的影响

慢性阻塞性肺病(COPD)患者长期处于低氧和高碳酸血症状态,传统给氧方法是采用持续低流量吸入,以防呼吸抑制,加重低氧血症和二氧化碳(CO_2)潴留,即使在COPD急性发作期,患者严重缺氧也禁用高浓度的氧气吸入。我们对一组急性发作期的COPD患者给予较高浓度的氧气吸入,以观察其对呼吸的影响。材料和方法 COPD急性发作期37例(男31,女6),年龄42～79岁,平均61岁。全部患者动脉血氧分压(PaO_2)均低于10.67kPa,其中Ⅱ型呼吸衰竭19例(PaO_2<8kPa,PaCO_2>6.7khPS)。     

中心静脉-动脉血二氧化碳分压差联合液体负荷状态评价感染性休克预后的价值

目的探讨中心静脉-动脉血二氧化碳分压差[central venous-arterial carbon dioxide partial difference,P(cv-a)CO_2]联合液体负荷状态评价感染性休克预后的价值。方法收集2015年10月—2017年3月我科收治的95例感染性休克患者资料,依据治疗72 h后有无液体过负荷及P(cv-a)CO_2将患者分为4组,A组为液体过负荷+P(cv-a)CO_2≥6 mmHg(1 mmHg=0.133 kPa);B组为非液体过负荷+P(cv-a)CO_2≥6 mmHg;C组为液体过负荷+P(cv-a)CO_26 mmHg;D组为非液体过负荷+P(cv-a)CO_26 mmHg,比较各组28 d和90 d的病死率、机械通气时间、ICU住院时间、住院时间的差异。结果 4组间机械通气时间、ICU住院时间、住院时间、28 d和90 d的病死率差异均有统计学意义(P0.05)。结论 P(cv-a)CO_2和液体过负荷状态可以联合评价感染性休克的预后。     

慢性肺心病酸中毒补硷的计算

问:代谢性酸中毒病人的CO_2结合力都低于正常“50ml”,可用“50减病人CO_2结合力”后再按计算的公式补硷。但是,肺心病人呼吸性酸中毒时的CO_2结合力多比正常人还高,怎样计算补硷?     

点阵激光联合解毒方对地方性砷中毒掌跖角化的疗效观察

目的观察CO_2点阵激光联合解毒方治疗地方性砷中毒掌跖角化临床疗效。方法选取56例地方性砷中毒掌跖角化患者,随机分为2组。对照组30例,予CO_2点阵激光治疗;试验组26例,予CO_2点阵激光+解毒方,观察临床疗效。结果试验组和对照组治疗后临床症状和体征积分比较,差异有统计学意义。对照组、试验组有效率两者比较差异有统计学意义。试验组和对照组患者均未出现不良反应。结论以CO_2点阵激光联合解毒方治疗地方性砷中毒掌跖角化具有肯定疗效。     

经皮CO_2监测和睡眠呼吸障碍

作者报导睡眠呼吸障碍患者应用非创伤性经皮CO_2计的情况。共观察睡眠呼吸暂停综合征3例及慢性呼吸功能不全4例。资料表明呼吸功能不全患者在睡眠时血气紊乱较睡眠呼吸暂停患者来得重,并表职经皮CO_2分压(Ptc CO_2)之增加主要与睡眠深度有关,而与单纯呼吸暂停无关。呼吸暂停3例中只2例的Ptc CO_2在睡眠时有轻度增高而呼吸功能不全患者     

碳酸饮料对胃食管反流病影响的系统性回顾

<正> 18世纪中晚期,英国人Joseph Priestley发现将水悬放于啤酒发酵池上能产生CO_2并溶于水,这种冒泡的饮料即为苏打水。碳酸饮料包括苏打水、啤酒、汽水、可乐等,其主要特性有碳酸化、酸性、高含量糖或人工甜味剂。碳酸饮料中溶解的CO_2在减压状态下产生气泡,温度和压力可影响溶解状态的CO_2转变为气体并释放的速率,因此饮料罐打开后能产生气泡。酸性是众多碳酸饮料的共同化学特性,由     

纤支镜对呼吸道急症的管理

【气道管理的重要性】正常的肺有足够能力保持人体血气处于正常范围,如进气2分钟不使CO_2排出,则PacO_2迅速增加到80mmHg,形成呼酸,P_ACO_2亦升至80mmHg。如过度通气几分钟便又能将肺内CO_2几乎全部呼出,继之血液和组织液内的CO_2也通过肺呼出,形成呼碱。血pH在过度通气15～20秒开始上升,2～     

在人体红细胞内生长的恶性疟原虫缺乏α-酮戊二酸脱氢酶活力而有固定CO_2活性

Roth等报道了鸭疟原虫和恶性疟原虫中有谷氨酸脱氢酶,而且感染恶性疟原虫的红细胞的α-酮戊二酸含量要比未感染的约高4倍。红细胞中CO_2固定的其他途径也可能是α-酮戊二酸量增加。倘若能肯定由~(14)C标记的谷氨酸形成的~(14)C α-酮戊二酸代谢到~(14)CO_2,则表示有α-酮戊二酸脱氢酶存在于恶性疟原虫中,它至少是柠檬酸循环的一个功能性步骤。Homewood和Neame报道鸭疟原虫、伯氏疟原虫和诺氏疟原虫可固定CO_2,但是还未确证究竟CO_2是由虫本身固定的还是由宿主细胞固定。如能确定寄生于人体的恶性疟原虫能否固定相当量的CO_2则是非常有意义的。本文主要采用[1-~(14)C]谷     

肺大疱患者呼吸衰竭时的机械通气治疗

目的：比较2种潮气量水平机械通气治疗肺大疱患者发生呼吸衰竭时的疗效及安全性。方法：63例发生呼吸衰竭的肺大疱患者随机分为小潮气量组（L组）和常规潮气量组（O组）,给予气管插管接呼吸机通气,分别采用小潮气量联合低水平呼气末正压（PEEP）通气和常规潮气量联合低水平PEEP通气,比较2组呼吸衰竭改善情况、气压伤发生情况。结果：治疗后2组患者全身症状改善明显,血气主要指标pH值、PaO2、PaCO2较治疗前明显改善（P〈0.05）;2组间比较,除PaCO2外,其余血气指标差异无显著性。L组仅1例患者发生气胸,O组有9例患者发生气胸,差异有显著性（P〈0.05）。结论：小潮气量联合低水平PEEP机械通气治疗肺大疱患者发生呼吸衰竭疗效肯定,可以减少气胸等并发症,值得临床推广应用。     

Effect of tidal volume and positive end-expiratory pressure on compliance during mechanical ventilation.

In 12 patients requiring therapy with mechanical ventilation for acute respiratory failure, total static compliance (Cst) increased from 29 +/- 4 ml/cm H2O at a tidal volume (TV) of 5 ml/kg to 42 +/- 7 ml/cm H2O at a TV of 15 ml/kg. Similarly, Cst increased from 42 +/- 7 ml/cm H2O to 52 +/- 8 ml/cm H2O between 0 and 6 cm H2O of positive end-expiratory pressure (PEEP). At high levels of pulmonary inflation (ie, high PEEP and large TV) compliance decreased. The changes of total respiratory compliance with TV were mainly due to changes in pulmonary compliance. With PEEP, the functional residual capacity increased, and specific compliance did not change. Two mechanisms may be responsible for the changes in compliance. First, varying TV or PEEP will alter the position of tidal ventilation on the pressure-volume curve, resulting in an increase in compliance with increasing TV and PEEP up to a point, where overdistention occurs and compliance decreases. Secondly, the function of the surface-lowering substance may be altered in acute pulmonary parenchymal disease, thus disturbing the regulation of surface tension over the range of pulmonary inflation studied.     

Interaction of Vagal Lung Afferents with Inhalation of Histamine Aerosol in Anesthetized Dogs

In seven alpha-chloralose anesthetized dogs we examined the contribution of lung afferents to the rapid, shallow breathing induced by inhalation of 10 breaths of histamine aerosol. In four spontaneously breathing dogs, the inhalation of histamine caused an increased respiratory frequency, decreased tidal volume, and decreased dynamic lung compliance. Selective blockade of pulmonary C-fibers abolished a reflex-induced increase in respiratory frequency but did not significantly affect the reductions in tidal volume or lung compliance. Terbutaline treatment in combination with C-fiber blockade abolished the reductions in tidal volume and lung compliance induced by histamine. In three separate alpha-chloralose anesthetized, open-chest, mechanically ventilated dogs, we recorded an increase in the inspiratory activity of rapidly adapting pulmonary stretch receptors (RARs) induced by the inhalation of histamine aerosol. Selective C-fiber blockade abolished histamine-induced increases in RAR activity while only partially attenuating reductions in lung compliance. We conclude that the increase in RAR activity induced by histamine depends on intact C-fibers and not on a direct effect of histamine on RARs or an indirect effect of histamine reducing lung compliance. In addition, our data illustrate the multiple interactions that occur between the various vagal afferents and their roles in the reflexes induced by histamine inhalation. Accepted for publication: 2 December 1999     

Ventilatory control after pulmonary resection

Because pulmonary resection decreases pulmonary compliance, the effects of resection on ventilation might be similar to the known effects of elastic loading. We evaluated the breathing pattern and ventilatory drive in 12 patients before and after pulmonary resection with mean tissue loss of 4 segments. During resting ventilation, the only significant change after resection was a decrease in inspiratory time (Tl). At a higher level of minute ventilation (VE), induced by CO2 rebreathing, significant changes included increased respiratory frequency, decreased tidal volume and Tl, and increased occlusion pressure (P0.1). Both ventilation and occlusion pressure responses to CO2 (delta VE/delta PACO2, delta P0.1/delta PACO2) were unchanged after resection. We conclude that increased ventilation induced by CO2 rebreathing unmasks a breathing pattern after pulmonary resection which is similar to that seen with breathing against an external elastic load.     

How does positive end-expiratory pressure decrease pulmonary CO2 elimination in anesthetized patients?

In anesthetized, mechanically ventilated patients, 10 cm H2O positive end-expiratory pressure (PEEP10) immediately decreased the CO2 volume exhaled per breath (V(CO2,br)) by 96%, as exhaled tidal volume (VT) decreased to expand functional residual capacity during the first 8 breaths after PEEP10 began. Then, the sustained decrease in V(CO2,br) for over 10 min was due to the 19% decrease in cardiac output (QT, decreased CO2 delivery from tissues to lung) and to the decrease in alveolar ventilation (VA). In turn, decreased VA resulted from decreased VT (loss of inspired volume into the compressible volume of the ventilating circuit) and possibly from increased physiological dead space, due to the potential for new high alveolar ventilation-to-perfusion (VA/Q) lung regions. V(CO2,br) increased and recovered to baseline by 20 min of PEEP10 ventilation because QT increased to augment the CO2 delivery to the lung and alveolar P(CO2) increased (increased mixed venous P(CO2) and tissue CO2 retention) to increase V(CO2,br) while alveolar VT remained depressed. End-tidal P(CO2) (PET(CO2) progressively increased during PEEP10 and did not detect the decrease in V(CO2,br) during PEEP10 ventilation because PET(CO2) does not account for exhaled volume.     

Inhaled nitric oxide combined with prostacyclin and adrenomedullin in acute respiratory failure with pulmonary hypertension in piglets

Our aim was to evaluate if the combined inhalation of both nitric oxide (iNO) and aerosolized prostacyclin or iNO and adrenomedullin (ADM) is more effective in lowering pulmonary arterial pressure (PAP) and improving oxygenation than nitric oxide alone in an animal model with pulmonary hypertension (PH). Moreover, we studied the effect on pulmonary mechanics, surfactant activity, and pulmonary oxidative stress of the different treatments. Twenty-eight piglets with acute lung injury induced by lung lavages with saline were randomized to receive nitric oxide, nitric oxide plus prostacyclin, nitric oxide plus ADM or saline, after. Dynamic compliance, tidal volume, and airway resistance were measured. Lung tissue oxidation was evaluated by measuring total hydroperoxide and advanced oxidation protein products in bronchial aspirate samples. Surface surfactant activity was studied using Capillary Surfactometer. Inhaled nitric oxide combined with prostacyclin or ADM was more effective than nitric oxide alone in lowering PAP and improving oxygenation. Nitric oxide alone or combined increased lung compliance and tidal volume, and decreased airway resistance. No effects on surfactant surface activity and lung tissue oxidation were observed. The treatment with nitric oxide alone or combined with prostacyclin or ADM were effective in decreasing mean PAP and improving oxygenation in a piglet model of PH. However, nitric oxide plus prostacyclin and nitric oxide plus ADM were more effective than nitric oxide alone. The combination of aerosolized prostacyclin and ADM with nitric oxide might have a role in the treatment of infants with PH refractory to nitric oxide alone.     

Volume reduction surgery impairs immediate postoperative pulmonary function in canine emphysema

RATIONALE: In severe pulmonary emphysema, lung volume reduction surgery (LVRS) improves pulmonary function over a 2-yr period in selected patients. However, the changes in lung function and maximal flow (Vmax) occurring immediately postoperatively are not clear and may contribute to the high morbidity observed. In the present study, we used a chronic canine model of upper lobe emphysema to address this question. METHODS: Bilateral upper lobe emphysema was produced by the intrabronchial administration of papain. Measurements were made before and immediately after LVRS was performed. A vacuum-assisted surgical system (VALR Surgical System; Spiration, Redmond, WA) that deploys a compression sleeve over portions of the disease tissue was used to produce LVRS. Changes in Vmax were interpreted in terms of the wave-speed theory of flow limitation in which a pressure sensor was placed into the airway to determine the site of limitation and intrabronchial pressures. RESULTS: In the emphysema group, total lung capacity postemphysema increased to approximately 20% above the preemphysema value, whereas Vmax was reduced as compared with a control group. After LVRS, tidal respiratory compliance and Vmax decreased, whereas lung elastic recoil and frictional resistance increased in both the emphysema and control groups as compared with presurgery. CONCLUSION: The acute effect of LVRS leads to an impairment in lung mechanical properties. These changes could contribute to ventilatory complications, including the difficulty of weaning patients from mechanical ventilation and the mortality observed from this procedure.     

Predictors of weaning outcome in chronic obstructive pulmonary disease patients.

Several threshold values for predicting weaning outcome from mechanical ventilation have been proposed. These values, however, have been obtained in nonhomogeneous patient populations. The aim of the present study was to determine the threshold values in chronic obstructive pulmonary disease (COPD) patients and compare them to those reported for nonhomogeneous patient populations. The initial weaning trial included 81 COPD patients. Fifty-three of them underwent a successful weaning trial, whereas 28 failed it. The latter were enrolled into the present investigation, and were restudied during a subsequent successful trial. The weaning indices used were those reported in the literature. The threshold values obtained were within 10% of those reported for a nonhomogeneous patients population only for tidal volume and effective compliance. The classification error was <20% for maximal inspiratory pressure (MIP), occluded inspiratory pressure swing (deltaPI)/MIP, rapid and shallow breathing (respiratory frequency/tidal volume), and compliance, rate, oxygenation, pressure index (CROP), whereas the area under the receiver operating characteristic curves was >0.9 only for deltaPI/MIP and CROP. In conclusion, the threshold values obtained in chronic obstructive pulmonary disease patients who failed the first weaning attempt differed from those previously reported. Although a gold standard weaning index is not available for chronic obstructive pulmonary disease patients, the occluded inspiratory pressure swing/ maximal inspiratory pressure and compliance, rate, oxygenation, pressure index may be candidates for such a role.     

2型糖尿病患者运动试验时肺气体交换功能变化初探

目的　探讨糖尿病患者运动能力及其运动时肺的通气与气体交换功能的变化。方法无明显慢性并发症住院的 2型糖尿病患者 2 1名和健康非吸烟对照组 2 0名进行限时递增负荷运动试验 ,测其静息时和运动中肺的通气与气体交换量的变化。结果　糖尿病患者最大运动负荷量、运动末的最大每分耗氧量及每搏耗氧量均较对照组低 ,运动末的最大每分通气量、最大潮气量、最大呼吸频率、最大心率与对照组差异无显著性 ;而呼吸商在运动前后均显著高于对照组 (P <0 .0 1)。结论　无明显慢性并发症的糖尿病患者运动能力显著下降 (P <0 .0 1) ,但运动中肺的通气功能无异常改变 ,推测其运动能力的下降可能与肌肉组织氧的摄取与利用障碍有关     

Ventilatory response to exercise in patients with major aortopulmonary collateral arteries after definitive surgery

Patients with pulmonary atresia and major aortopulmonary collateral arteries (MAPCAs) may be at risk for both ventilatory impairment and abnormal pulmonary circulation after definitive surgery. We measured the ventilatory response to exercise in 16 patients with MAPCAs after definitive surgery (group A) and compared the results with those in 16 patients with tetralogy of Fallot with pulmonary atresia and without MAPCAs after definitive operation (group B), with 24 patients with tetralogy of Fallot after one-stage repair without previous palliation (group C), and with 48 healthy subjects (group D). Pulmonary function and treadmill exercise tests were performed. Arterial blood gases were also analyzed and the dead space to tidal volume ratio calculated. In group A, the vital capacity, diffusion capacity, and peak oxygen uptake were lowest (p <0.001), whereas the ventilatory equivalent for carbon dioxide was highest and its value at peak exercise correlated with age at time of surgery (r = 0.73, p <0.002). The arterial oxygen tension decreased progressively in group A and its value at peak exercise inversely correlated with the mean pulmonary artery pressure in all patients (r = -0.75, p <0.001). The arterial carbon dioxide tension decreased significantly at peak exercise in controls but showed no change in group A. The dead space to tidal volume ratio decreased during exercise in patients without MAPCAs and in controls but increased in group A, and the dead space to tidal volume ratio at peak exercise was inversely correlated with vital capacity in all patients (r = -0.77, p <0.001). Diffusion capacity independently predicted arterial carbon dioxide tension and dead space ventilation during exercise. Marked restrictive ventilatory impairment with low diffusion capacity along with a pulmonary obstructive change contributed to the abnormal pulmonary gas exchange during exercise in group A. Earlier repair of MAPCAs may prevent the progression of the impaired ventilatory response to exercise in these patients.