一氧化氮合酶3基因多态性与复发性早期自然流产的关系

目的探讨一氧化氮合酶3(nitric oxide synthase 3,NOS3)基因第4内含子27bp数目可变串联重复序列(variable number of tandem repeat,VNTR)多态性和第7外显子894(G/T)多态性与复发性早期自然流产(recurrent early spontaneous abortion,RESA)的相关性。方法选取140例RESA患者和140名健康妇女,应用聚合酶链反应-琼脂糖凝胶电泳法检测NOS3基因第4内含子VNTR多态性,聚合酶链反应-限制性片段长度多态性分析技术检测第7外显子894(G/T)多态性。结果RESA组aa ba基因型频率和a等位基因频率与正常对照组相比差异有统计学意义(χ2=4.51,P<0.05;χ2=4.29,P<0.05)。与bb基因型相比,携带a等位基因的妇女与RESA显著相关(OR为1.8,95%CI:1.04~3.24)。RESA组TT GT基因型频率和T等位基因频率与正常对照组相比差异无统计学意义(χ2=1.16,P>0.05;χ2=1.12,P>0.05)。与GG基因型相比,携带T等位基因的妇女与RESA无相关。结论NOS3基因第4内含子27bp数目可变的串联重复序列多态性与复发性自然流产密切相关,NOS3基因第7外显子894G/T多态性与RESA无明显相关性,a等位基因是RESA重要的遗传易感基因。     

The acute effects of insulin on the cardiorespiratory responses to hypoxia in streptozotocin‐induced diabetic rats

Aims: We examined whether or not streptozotocin (STZ)‐induced diabetic rats, which have a lower heart rate (HR, beats min^?1) than control rats, could maintain hypoxic ventilatory response. Methods: Twenty‐six Wistar rats, which had been injected with STZ (60 mg kg^?1, EXP) or vehicle (0.1 m citrate buffer, CONT) intraperitoneally at 9 weeks of age, had their cardiorespiratory responses to normoxia and 12%O₂ examined after 5 weeks. Results: Compared with CONT rats, EXP rats had a higher blood glucose [24 ± 3 vs. 5 ± 1 (mean ± SD) mmol L^?1], a lower body weight (320 ± 23 vs. 432 ± 24 g), lower HR (303 ± 49 vs. 380 ± 44 in normoxia, and 343 ± 56 vs. 443 ± 60 in hypoxia) and a lower mean arterial blood pressure (MAP) (89 ± 6 vs. 102 ± 10 mmHg in hypoxia). In contrast, both groups had similar values in ventilation (), –metabolic rate (MR) ratio and arterial blood gases (ABGs). In EXP rats, with an acute insulin supplement (i.v., 0.75 U h^?1 for 1.5–2 h), not only blood glucose, but also HR, and MAP were normalized as those obtained in CONT rats, and in hypoxia further increased without affecting –MR ratio and ABGs. Such acute cardiorespiratory stimulating effects of insulin could not be obtained in non‐diabetic rats (n = 7, 355 ± 24 g), in which euglycaemia (mean 6.4 mmol L^?1) was maintained during the measurements. Conclusions: Our results suggest that, in STZ‐induced diabetic rats: (1) ventilation is hardly suppressed by hyperglycaemia, (2) cardiorespiratory responses can be acutely stimulated by short insulin injection, and (3) the effects, including those through acute blood glucose normalization, are possibly specific for the diabetic impairments.     

Role of potassium in the regulation of systemic physiological function during exercise

In exercise, potassium (K⁺) is released from contracting muscle predominately through K⁺ channels associated with the repolarization phase of the action potential. Increases in extracellular K⁺ are directly related to increases in metabolic rate and may reach concentrations as high as 8–9 mm in the arterial blood during exhaustive work. Exercise-induced hyperkalaemia has been implicated in several physiological processes, in particular skeletal muscle fatigue, hyperaemia, pressor reflex, arterial chemosensitivity and myocardial stability. There is no direct evidence to show that hyperkalaemia causes muscle fatigue, although raised extracellular [K⁺] may contribute to fatigue during prolonged tetani by depressing the propagation of the action potential down the t-tubule system, thus impairing the release of Ca²⁺ from the sarcoplasmic reticulum. The vasodilating properties of K⁺ may transiently contribute to the early phase of exercise hyperaemia and interact synergistically with other vasoactive substances to cause relaxation by hyperpolarizing K⁺ channels in vascular smooth muscle. Hyperkalaemia has been implicated in the regulation of arterial blood pressure through activation of the muscle afferent reflex where potassium-depolarized C fibres may contribute to a reflex increase in arterial blood pressure. K⁺ can also increase ventilation and the sensitivity of the ventilatory response to hypoxia through direct excitation of the arterial chemoreceptors. Finally, to maintain myocardial electrical stability in exercise, there is a beneficial interaction between raised K⁺ and catecholamines on the heart, so that when they combine, each offsets the other's deleterious effects.     

Near‐infrared spectroscopy determined brain and muscle oxygenation during exercise with normal and resistive breathing

To elevate effects of carbon dioxide (CO₂) retention by way of an increased respiratory load during submaximal exercise (150 W), the concentration changes of oxy‐ (ΔHbO₂) and deoxy‐haemoglobin (ΔHb) of active muscles and the brain were determined by near‐infrared spectroscopy (NIRS) in eight healthy males. During exercise, pulmonary ventilation increased to 33 (28–40) L min^–1 (median with range) with no effect of a moderate breathing resistance (reduction of the pneumotach diameter from 30 to 14 and 10 mm). The end‐tidal CO₂ pressure (P_ETCO ₂) increased from 45 (42–48) to 48 (46–58) mmHg with a reduction of only 1% in the arterial haemoglobin O₂ saturation (S_aO ₂). During control exercise (normal breathing resistance), muscle and brain ΔHbO₂ were not different from the resting levels, and only the leg muscle ΔHb increased (4 (–2–10) μM , P < 0.05). Moderate resistive breathing increased ΔHbO₂ of the intercostal and vastus lateralis muscles to 6 ± (–5–14) and 1 (–7–9) μM (P < 0.05), respectively, while muscle ΔHb was not affected. Cerebral ΔHbO₂ and ΔHb became elevated to 6 (1–15) and 1 (–1–6) μM by resistive breathing (P < 0.05). Resistive breathing caused an increased concentration of oxygenated haemoglobin in active muscles and in the brain. The results indicate that CO₂ influences blood flow to active skeletal muscle although its effect appears to be smaller than for the brain.     

Numerical simulation of aerosol particle transport by oscillating flow in respiratory airways

Particle transport by oscillating flow in a tapered channel or in a tapered tube was computed from the complete equations of motion. These geometries represent a simplified model of the divergent flow field of the mammalian bronchial tree. The computed deformation profile of a line of particles, transported by the oscillatory motion, was compared with prior experimental results and analytical calculations. All three methods agree that there is transport in the divergent direction of the tube by an axial stream of steady drift in the core for moderately high frequency of oscillation (Womersley parameter in the range of 1 to 10). Bidirectional flow is established by an annular stream in the convergent direction, with no net flow on integral cycles of the oscillating fluid. At higher frequency, however, the steady stream transforms to a different shape in the tapered tube, with transport in the divergent direction nearer the walls of the tube, rather than in the core. Transport by the continuing streams with oscillatory ventilation of the respiratory tract should deliver medicinal aerosols of low intrinsic particle mobility to the peripheral regions of the lungs.     

Thoracic duct lymph and PEEP studies in anaesthetized dogs

PEEP impedes thoracic duct drainage (LF). This can be counteracted by a thoracic duct fistula. Consequently, lung oedema (LOE) should develop during PEEP more slowly with LF at atmospheric pressure (LF_AP) than with LF against jugular venous pressure (LF_JVP). In 12 anaesthetized dogs LOE was produced by Ringer's solution i.v. (2.5 ml/min per kg) for 6 h during PEEP (10 mmHg) with either LF_AP or LF_JVP. Ringer's+PEEP greatly increased aortic, pulmonary artery and wedge pressures, JVP, and cardiac output. Colloid osmotic pressures in plasma and lymph were drastically reduced, pulmonary effective filtration pressure (EFP) rose by about 20 mmHg. LF_JVP increased 7-fold, LF_AP about 19-fold, the respective loss of plasma proteins was 1.83 and 1.06 g/kg during 6 h. Thermal-dye extravascular lung water showed an increment of 68 with LF_JVP versus 43 l/h/g per mmHg with LF_AP. Final lung water content was at any EFP (12.8–31.9 mmHg) lower with LF_AP than with LF_JVP amounting 512 with LF_JVP versus 377 l/g/per mmHg with LF_AP. LF_AP decreased the development of LOE during PEEP by bypassing the PEEP-induced high JVP and thus facilitating the removal of interstitial fluid. It is hypothesized that a thoracic duct fistula might aid the treatment of patients with LOE due to ARDS and therefore requiring high levels of PEEP.     

机械通气下应用肺表面活性物质治疗新生儿肺炎合并呼吸衰竭的疗效

目的：探讨新生儿肺炎合并呼吸衰竭治疗中机械通气下应用肺表面活性物质的疗效。方法：回顾性选取2017年2月至2022年2月无锡市儿童医院新生儿科收治的新生儿肺炎合并呼吸衰竭患儿80例,依据治疗方法分为机械通气下应用肺表面活性物质治疗组(观察组)、机械通气治疗组(对照组)两组,各40例。分析两组患儿血气指标、平均动脉压(MAP)和呼吸力学指标、机械通气时间、总吸氧时间、住院时间、并发症发生情况之间的差异。结果：治疗前,两组患儿的动脉血氧分压(PaO₂)、氧合指数(PaO₂/FiO₂)、动脉血二氧化碳分压(PaCO₂)、氢离子浓度指数(pH)、MAP、呼气末正压(PEEP)、平台压(Pplat)、气道峰压(PIP)之间比较,差异均无统计学意义(P> 0.05);治疗后,两组患儿的PaO₂、PaO₂/FiO₂均高于治疗前,PaCO₂、MAP、PEEP均低于治疗前,差异均具有统计学意义(P <0.05),但治疗...     

Absence of COVID-19 Disease Among Chronically Ventilated Nursing Home Patients

ObjectiveTo describe the experience of COVID-19 disease among chronically ventilated and nonventilated nursing home patients living in 3 separate nursing homes.DesignObservational study of death, respiratory illness and COVID-19 polymerase chain reaction (PCR) results among residents and staff during nursing home outbreaks in 2020.Setting and Participants93 chronically ventilated nursing home patients and 1151 nonventilated patients living among 3 separate nursing homes on Long Island, New York, as of March 15, 2020. Illness, PCR results, and antibody studies among staff are also reported.MeasurementsData were collected on death rate among chronically ventilated and nonventilated patients between March 15 and May 15, 2020, compared to the same time in 2019; prevalence of PCR positivity among ventilated and nonventilated patients in 2020; reported illness, PCR positivity, and antibody among staff.ResultsTotal numbers of deaths among chronically ventilated nursing home patients during this time frame were similar to the analogous period 1 year earlier (9 of 93 in 2020 vs 8 of 100 in 2019, P = .8), whereas deaths among nonventilated patients were greatly increased (214 of 1151 in 2020 vs 55 of 1189 in 2019, P < .001). No ventilated patient deaths were clinically judged to be COVID-19 related. No clusters of COVID-19 illness could be demonstrated among ventilated patients. Surveillance PCR testing of ventilator patients failed to reveal COVID-19 positivity (none of 84 ventilator patients vs 81 of 971 nonventilator patients, P < .002). Illness and evidence of COVID-19 infection was demonstrated among staff working both in nonventilator and in ventilator units.Conclusions and ImplicationsCOVID-19 infection resulted in illness and death among nonventilated nursing home residents as well as among staff. This was not observed among chronically ventilated patients. The mechanics of chronic ventilation appears to protect chronically ventilated patients from COVID-19 disease.     

无创高频振荡通气在极低出生体重早产儿呼吸窘迫综合征初始呼吸支持治疗中的应用

目的探讨经鼻无创高频振荡通气(NHFOV),在呼吸窘迫综合征(RDS)极低出生体重早产儿初始呼吸支持治疗的临床疗效。 方法选择2018年2月至2020年4月,于徐州市中心医院新生儿重症监护病房(NICU)治疗的92例RDS极低出生体重早产儿为研究对象。采用随机数字表法,将其分为NHFOV组(n＝48,采取NHFOV治疗)及经鼻持续气道正压通气(NCPAP)组(n＝44,采取NCPAP治疗)。对2组RDS极低出生体重早产儿一般临床资料,无创通气治疗前、后动脉血气分析指标,疗效,呼吸支持治疗相关并发症发生率及患儿死亡率,采用成组t检验、χ²检验及Mann-Whitney U检验进行统计学比较。本研究经徐州市中心医院医学伦理委员会审核批准(审批文号：XZXY-LJ-20170328-006),并且与患儿监护人均签署临床研究知情同意书。 结果①一般临床资料比较：2组RDS极低出生体重早产儿的性别、出生胎龄与体重及生后1、5 min Apgar评分,入院日龄及分娩前24 h母亲糖皮质激素使用率等一般临床资料比较,差异均无统计学意义(P>0.05)。② 2组RDS极低出生体重早产儿动脉血气分析指标组间比较：NHFOV组RDS极低出生体重早产儿无创通气治疗后1 h、24 h动脉血二氧化碳分压(PaCO₂)分别为(45.8±6.5) mmHg(1 mmHg＝0.133 kPa)及(40.8±4.7) mmHg,均显著低于NCPAP组的(49.3±5.7) mmHg及(44.2±5.2) mmHg;治疗后1 h、24 h动脉血氧分压(PaO₂)与吸入氧浓度分数(FiO₂)比值(P/F)分别为(198.8±30.5) mmHg及(215.1±32.1) mmHg,均显著高于NCPAP组的(176.4±28.1) mmHg及(190.0±29.7) mmHg,并且上述差异均有统计学意义(t＝2.809、3.301、3.663、3.881,P＝0.003、<0.001、<0.001、<0.001)。③2组动脉血气分析指标分别进行组内比较均为：无创通气治疗后24 h的pH值及治疗后1、24 h的PaCO₂水平,均较治疗前改善,而且治疗后24 h的P/F值高于治疗后1 h,并且差异均有统计学意义(P<0.05)。④无创通气疗效比较：NHFOV组RDS极低出生体重早产儿无创通气治疗后,肺表面活性剂(PS)使用率及有创机械通气率(22.9%、6.3%),均显著低于NCPAP组(45.5%、20.5%),并且差异均有统计学意义(χ²＝5.219、4.084,P＝0.022、0.043)。2组RDS极低出生体重早产儿无创通气时间、柠檬酸咖啡因使用率、频繁呼吸暂停发生率及总用氧时间比较,差异均无统计学意义(P>0.05)。⑤2组RDS极低出生体重早产儿鼻损伤、肺气漏、新生儿坏死性小肠结肠炎(NEC)、Ⅲ~Ⅳ级脑室内出血(IVH)、早产儿视网膜病(ROP)(≥Ⅱ期)及支气管肺发育不良(BPD)发生率,以及患儿死亡率比较,差异均无统计学意义(P>0.05)。 结论与NCPAP比较,NHFOV用于RDS极低出生体重早产儿初始呼吸支持治疗,能改善氧合、减少二氧化碳(CO₂)潴留、减少有创机械通气及PS使用,同时不增加呼吸支持治疗相关并发症发生。     

喉罩全麻通气用于妇产科临床麻醉的麻醉效果及安全性评价

目的:探究妇产科麻醉中采用喉罩全麻通气的麻醉效果与安全性。方法:选取本院收治的妇产科手术患者90例,按照通气方式的不同分为2组,对照组实施气管内插管通气,观察组实施喉罩全麻通气,比较两组患者置管成功率、收缩压、舒张压、平均动脉压、心率的变化。结果:对照组通气后收缩压与舒张压水平高于通气前(P<0.05);观察组通气后收缩压与舒张压水平均低于对照组(P<0.05);对照组通气后平均动脉压与心率水平均比通气前高(P<0.05);观察组通气后平均动脉压与心率水平均比对照组低(P<0.05)。结论:产科麻醉中采用喉罩全麻通气麻醉,麻醉效果与安全性都较高。