三种兔单肺通气模型的比较

目的采用三种方法建立兔单肺通气模型并比较其效果。方法日本大耳白兔30只,随机分为3组(即A、B、C组)各10个,分别采用自制双腔气管导管法、左主支气管结扎法和插管过深法。呼吸机通气参数为:FiO21.0,RR 40/min,VT 10 mL/kg。单肺通气2 h后恢复双肺通气。记录各组单肺通气实施的一次成功率、总成功率、从气管切开开始到单肺通气实施所需要的时间、动物失血量。实验结束后开胸测量兔气管、左主支气管、右主支气管的长度和内径。结果各组进入实验的动物数分别为10、6、8只。与B、C组比较,A组一次成功率和总成功率高,所需时间明显较少(P<0.01),且出血量明显少于B组(P<0.01)。结论采用自制双腔气管导管能迅速有效的建立单肺通气模型,是用于研究与单肺通气相关病理生理机制的理想模型。     

呼气末二氧化碳分压、C-反应蛋白/白蛋白比值及综合脱机指数对重型颅脑损伤机械通气患者撤机失败的预测价值

摘要 目的：探讨呼气末二氧化碳分压（PetCO₂）、C-反应蛋白/白蛋白比值（CRP/Alb）及综合脱机指数（IWI）对重型颅脑损伤机械通气患者撤机失败的预测价值。方法：选择2020年1月至2022年6月在安徽中医药大学附属六安医院进行机械通气的重型颅脑损伤患者96例作为研究对象,按照撤机结局分为撤机失败组（n=31）和撤机成功组（n=65）。比较两组撤机前PetCO₂、CRP/Alb、IWI及临床参数。应用多因素Logistic回归分析重型颅脑损伤机械通气患者撤机失败的危险因素。应用受试者工作特征（ROC）曲线评价PetCO₂、CRP/Alb、IWI对重型颅脑损伤机械通气患者撤机失败的预测价值。结果：撤机失败组PetCO₂、CRP/Alb、急性生理功能和慢性健康状况评分系统II（APACHE II）评分显著高于撤机成功组,机械通气时间长于撤机成功组,IWI、格拉斯哥昏迷评分（GCS）显著低于撤机成功组（P<0.05）。多因素Logistic回归分析显示,PetCO₂≥37.01 mmHg、CRP/Alb≥0.97、IWI≤78.23、GCS≤5.90分、APACHE II评分≥26.17分、机械通气时间≥4.49 d是重型颅脑损伤机械通气患者撤机失败的危险因素（P<0.05）。ROC曲线分析结果显示PetCO₂、CRP/Alb、IWI、GCS、APACHE II对重型颅脑损伤机械通气患者撤机失败均有较高的敏感度、特异度, PetCO₂、CRP/Alb、IWI三项联合检测对重型颅脑损伤机械通气患者撤机失败预测的曲线下面积（AUC）高于PetCO₂、CRP/Alb、IWI、GCS、APACHE II单独检测。结论：PetCO₂、CRP/Alb及IWI联合评估对重型颅脑损伤机械通气患者撤机失败具有较高的预测价值。     

The influence of ventilation systems on water depth penetration of emergent macrophytes

1. Roots of emergent macrophytes depend on oxygen transported from aerial parts by diffusion and, in some species, by pressurised ventilation. The aim of this study was to determine if species with pressurised ventilation grow in deeper water in situ than species lacking this ability.
2. Species with pressurised ventilation grew significantly deeper than species lacking pressurised ventilation, and this was true in substrates with low as well as high redox potential.
3. Two species with low or non-detectable flow rates ( Schoenoplectus lacustris and Equisetum fluviatile , respectively) were found in unexpectedly deep water. Thus, pressurised ventilation is not a prerequisite for growth in deep water. It is, however, suggested that species with pressurised ventilation have a competitive advantage in deep water resulting in long-term competitive exclusion of species lacking pressurised ventilation.     

Temperature and respiratory function in ectothermic vertebrates

Pulmonary ventilation is adjusted to maintain balance between O₂ demands and CO₂ elimination, which is essential for acid–base status in land ectothermic vertebrates. Rising temperatures cause increases in O₂ consumption (Q₁₀ effect) and decreases in the O₂ affinity of hemoglobin (a rightward shift in the oxygen–hemoglobin dissociation curve). These changes in air-breathing ectotherms are not proportional, i.e., the increased ventilation is relatively smaller than the change in metabolic rate. Therefore, the ratio between ventilation and metabolic rate is reduced, and consequently blood pH changes inversely with temperature. The combination of high temperatures and hypoxia exposure results in an amplified increase of ventilation, which may be explained by the balance between increased O₂-demand and decreased O₂-supply as well as increased O₂-chemoreceptors sensitivity. High temperature also increases pulmonary diffusing capacity. Global warming is expected to have significant impacts on the world’s climate, with temperature changes affecting living organisms, in relation to their physiology and distribution. These physiological mechanisms and their capacity to respond appropriately to temperature illustrate the complexity of the relationship between ambient temperature and the respiratory function in ectothermic vertebrates, which are particularly susceptible to change in their environment.     

Anatomy of the gas canal system of Nelumbo nucifera

Nelumbo nucifera (Gaertn.) grows by extending a creeping rhizome through anaerobic sediments. Nodes form at intervals along the rhizome, each producing a single leaf, and gas canals channel air from the leaves throughout the petioles and rhizomes. The gas flow pathway was mapped by casting the canals in growing shoots with silicone and by blowing air through complexes of rhizomes and petioles. Air from a leaf flows to a rhizome through one of two petiolar canal pairs, joining with the lowermost of three canal pairs in the rhizome through a chamber in the node. The lowermost canal pair links these nodal chambers along the length of a rhizome, allowing air from a node to flow both forward, toward a growing shoot, and backward, toward preceding leaves. These linked chambers also connect with the middle pair of canals on their proximal side, enabling flow to proceed backward along the rhizome to an adjacent node. A chamber in the next node then diverts the flow into the upper canal pair. This pair leads to a third node and chamber from which the air vents to the atmosphere through the second petiolar canal pair. Thus, pressurised air from one leaf must flow backward through two nodes before it returns to the atmosphere. Forward flow also ventilates a shoot's growing tip, with air from the lowermost canal pair entering a chamber in the developing node which, as described above, connects with the middle canal. This allows the air to reverse direction at the tip and enter the vent flow pathway.     

早期经皮气管切开治疗原发性脑干出血的临床效果

目的:探讨早期经皮气管切开治疗原发性脑干出血中的临床效果。方法:选择2012年8月至2015年6月我院ICU收治的原发性脑干出血患者125例,按患者行气管切开的时间分组,以早期行气管切开(发病5 d内)定为观察组,发病5 d后行气管切开的患者定为对照组,对比两组患者的治疗效果。结果:两组患者的性别、年龄、APACHEII评分、GCS评分、疾病构成方面对比无明显差异(P0.05);观察组患者气管切开时机为(2.6±0.8)d,低氧血症发生的次数(20.6±5.5)次,镇静药物用量(132.8±23.4)mg,抗生素使用时间(11.2±0.9)d,机械通气时间(153.5±82.4)h,HAP发生率44.6%,病死率23.1%,均明显优于对照组患者,差异具有统计学意义(P0.05)。结论:早期气管切开有助于降低原发性脑干出血的死亡率,临床效果更好。     

无创正压通气序贯治疗急性左心衰合并呼吸衰竭患者的时机选择

目的:探讨无创正压通气序贯治疗急性左心衰合并呼吸衰竭患者的时机选择。方法:选择2013年6月-2015年8月我院收治的120例先行气管插管有创通气治疗的急性左心衰合并呼吸衰竭患者作为研究对象,病情得到控制后,按照拔管时间的长短分为A、B、C 3组,各40例,其中A组在进行自主呼吸30 min后拔管,B组在进行自主呼吸2 h后拔管,C组在进行自主呼吸24 h后拔管,拔管后全部患者均进行无创正压通气序贯治疗,比较3组患者治疗后血气分析结果、呼吸机相关肺炎发生率及脱机成功率。结果:13组患者无创正压通气治疗后的呼吸频率、心率、氧合指数、氧分压、二氧化碳分压及ph值均无明显差异(t1=1.402,t2=1.338,t1=0.738,t2=1.201,t1=0.969,t1=0.857,均P0.05);2A组患者的脱机成功率为7.50%,显著低于B组的77.50%与C组的82.50%,差异具有统计学意义(P0.05);A组患者的再插管率为92.50%,显著高于B组的22.50%与C组的17.50%,比较差异具有统计学意义(P0.05);A组患者的呼吸机相关肺炎发生率为45.00%,显著高于B组的12.50%与C组的10.00%,比较差异具有统计学意义(P0.05)。结论:急性左心衰合并呼吸衰竭患者在自主呼吸超过2 h后拔管,进行无创正压通气序贯治疗,可明显提高脱机成功率,降低再插管率和呼吸机相关肺炎发生率,值得临床推广。     

Resultados de la ventilación mecánica no invasiva en pacientes no candidatos a intubación en un hospital de subagudos. Estudio de seguimiento a un año

Elderly patients with multiple morbidity and do not intubate (DNI) orders frequently present with acute respiratory failure. There are data supporting the effectiveness of non-invasive ventilation (NIV) in this context. Our chronic disease hospital developed an integrated care clinical pathway for the use of NIV in acute respiratory failure in the emergency room and wards in 2010. The aim of this study was to assess the outcome of NIV in patients with acute respiratory failure who had a DNI order in a sub-acute care hospital.MethodsObservational, one year-follow up study. The main variables were in-hospital mortality and one year mortality. Other variables recorded were: demographics, clinical data, functional data, performance of daily life activities, dementia, arterial blood gases and re-admissions.ResultsThe study included a total of 102 patients, of which 22% were in institutions. The mean age 81 ± 7.47% males, with a Charlson index 3.7 ± 1, and Barthel index 54 ± 31. The overall mortality during the admission was 33% (34 patients). Among those patients ventilated outside the protocol indication, the mortality was significantly greater, at 71% (P > .05). Overall one-year survival rate was 46%. This survival rate was statistically higher in patients with obesity hypoventilation syndrome and a Barthel > 50.ConclusionsNIV is a useful technique in a hospital for chronic patients in an elderly population with a therapeutic ceiling. Despite their disease severity and comorbidity, acceptable survival rates are achieved. A correct case selection is needed. Obesity hypoventilation syndrome and those with Barthel index > 50 have a better prognosis.     

机械通气患者人工气道管理技术进展

机械通气技术在严重急慢性呼吸衰竭的患者抢救治疗中广泛应用,人工气道管理技术方法在机械通气过程中显示十分重要作用,有效的气道管理技术方法可减少机械通气过程中一些并发症如呼吸机相关性肺炎等。结合临床应用机械通气技术体会,本文主要对人工气道管理技术方法总结分析。     

A video and photographic study of aggregation,swimming and respiratory behaviour changes in the Grey Nurse Shark (Carcharias taurus) in response to the presence of SCUBA divers

The Grey Nurse Shark (Carcharias taurus) is a popular attraction for shark eco-tourism using SCUBA. The species is also ‘globally Vulnerable’ (IUCN 2008. List of Threatened Species. www.iucnredlist.org/). Magic Point (off Maroubra) in Sydney is favoured by recreational SCUBA divers wishing to observe these sharks. The objective of this study was to experimentally test the level of the activities of recreational SCUBA divers on shark behaviour. This study assessed the shark responses to diver group size (4, 8 and 12), time of day (am, noon and pm) and diver distance from the sharks (3?m and 6?m). The study found that diver activity does affect the aggregation, swimming and respiratory behaviour of sharks at this site, albeit at short-term levels. Diver group size had no significant effect on shark aggregation, but the proximity of divers to the sharks was crucial. Shark distribution in the cave changed significantly in the presence of divers at 3?m distance from the cave, but stayed unchanged at 6?m. This was particularly apparent in the presence of large groups of 12 divers at 3?m distance when sharks increased their swim speed and ventilation mechanism from ‘active’ to ‘RAM’ ventilation. Such change coincided with a sudden decrease in ventilation frequency. Our research suggests that these effects are short-term and that sharks resume their behaviour once the divers retreat. If divers abide by the current code of practice for diving at this site, it is unlikely that their activities will substantially impact Grey Nurse Sharks in the long term.