经鼻面罩BiPAP正压通气治疗重症支气管哮喘合并Ⅱ型呼吸衰竭的临床观察

目的观察经鼻面罩BiPAP无创正压通气治疗重症支气管哮喘合并Ⅱ型呼吸衰竭的临床效果。方法观察患者行呼吸机治疗前,治疗后4、12、24、48h的临床症状及血气分析。结果治疗后患者的临床症状、血气分析（pH、PaCO2、PaO2）均有显著改善,且无严重并发症发生。结论 BiPAP无创正压通气有助于呼吸改善,正确有效的护理措施对保证通气治疗的效果、减少并发症具有重要意义。     

Health-related quality of life and long-term prognosis in chronic hypercapnic respiratory failure: a prospective survival analysis

Background

Health-related quality of life (HRQL) is considered as an important outcome parameter in patients with chronic diseases. This study aimed to assess the role of disease-specific HRQL for long-term survival in patients of different diagnoses with chronic hypercapnic respiratory failure (CHRF).

Methods

In a cohort of 231 stable patients (chronic obstructive pulmonary disease (COPD), n = 98; non-COPD (obesity-hypoventilation syndrome, restrictive disorders, neuromuscular disorders), n = 133) with CHRF and current home mechanical ventilation (HMV), HRQL was assessed by the disease-specific Severe Respiratory Insufficiency (SRI) questionnaire and its prognostic value was prospectively evaluated during a follow-up of 2–4 years, using univariate and multivariate regression analysis.

Results

HRQL was more impaired in COPD (mean ± SD SRI-summary score (SRI-SS) 52.5 ± 15.6) than non-COPD patients (67.6 ± 16.4; p < 0.001). Overall mortality during 28.9 ± 8.8 months of follow-up was 19.1% (31.6% in COPD, 9.8% in non-COPD). To identify the overall role of SRI, we first evaluated the total study population. SRI-SS and its subdomains (except attendance symptoms and sleep), as well as body mass index (BMI), leukocyte number and spirometric indices were associated with long-term survival (p < 0.01 each). Of these, SRI-SS, leukocytes and forced expiratory volume in 1 s (FEV₁) turned out to be independent predictors (p < 0.05 each). More specifically, in non-COPD patients SRI-SS and most of its subdomains, as well as leukocyte number, were related to survival (p < 0.05), whereas in patients with COPD only BMI and lung function but not SRI were predictive.

Conclusion

In patients with CHRF and HMV, the disease-specific SRI was an overall predictor of long-term survival in addition to established risk factors. However, the SRI predominantly beared information regarding long-term survival in non-COPD patients, while in COPD patients objective measures of the disease state were superior. This on one hand highlights the significance of HRQL in the long-term course of patients with CHRF, on the other hand it suggests that the predictive value of HRQL depends on the underlying disease.     

无创辅助通气早产儿呼吸道感染病原菌分布 及影响因素分析

目的分析无创辅助通气早产儿呼吸道感染的病原菌及相关影响因素。方法选择2016年3月至2018年10月我院新生儿监护室收治的100例行无创辅助通气呼吸的早产儿为观察组。选择同期100例正常早产儿作为对照组。对两组患儿痰样本进行细菌鉴定,记录患儿基本情况并检测血中CD3~+、CD3~+/CD8~+、CD3~+/CD19~+和CD19~+/CD23~+水平。结果观察组患儿呼吸困难、发热、咳嗽、肺部喘鸣音及湿罗音发生率均高于对照组,差异有统计学意义(均P0.05)。观察组患儿血液中CD3~+、CD3~+/CD8~+水平明显低于对照组,CD3~+/CD19~+及CD19~+/CD23~+水平明显高于对照组,差异有统计学意义(均P0.05)。观察组患儿革兰阳性菌的感染率为17.00%,革兰阴性菌感染率为27.00%,其中金黄色葡萄球菌、大肠埃希菌和肺炎克雷伯菌的感染率占比相对较高。季节、通气时间、胎龄及出生体重是影响患儿呼吸道感染发生的独立性影响因素(P0.05)。结论无创辅助通气早产儿呼吸道感染病原菌以金黄色葡萄球菌、大肠埃希菌和肺炎克雷伯菌为主,季节、通气时间、胎龄及出生体重均是导致感染发生及发展的独立性影响因素。     

Blood oxygen levels and acid-base status following air exposure in an air-breathing fish, Channa argus: the role of air ventilation

1. Acute air exposure of an air-breathing fish Channa argus immediately induced hypercapnic acidemia while total CO2 content of blood remained unchanged. Upon reimmersion, paco2 and pHa quickly restored to pre-exposure levels followed by gradual rise of [HCO-3]. 2. Artificial air ventilation of air-exposed fish restored acid-base status and greatly depressed voluntary air ventilatory movements. We conclude that the major cause of acid-base disturbances occurring during air exposure is the reduced air convection.     

Acute altitude exposure and altered acid-base states. I. Effects on the exercise ventilation and blood lactate responses

This study examined the influence of acute altitude (AL) exposure alone or in combination with metabolic acid-base manipulations on the exercise ventilatory and blood lactate responses. Four subjects performed a 4 min, 30 W incremental test to exhaustion at ground level (GL) and a 4 min, 20 W incremental test during three acute exposures to a simulated altitude of 4200 m; (i) normal (NAL), (ii) following 0.2 g.kg-1 ingestion of sodium bicarbonate (BAL), and (iii) following 0.5 g.day-1 ingestion of acetazolamide for 2 days prior to exposure (AAL). VE.VO2-1 increased progressively throughout the incremental tests at AL and the minimum value was not related to a change in the blood lactate response. In contrast, the VE.VCO2-1 decreased initially to reach a minimum value at the same power output for each altitude trial and was related to a lactate threshold defined by a log-log transformation (r = 0.78). This transformation of the blood lactate data was not influenced by the altered acid-base states. The relative exercise intensity corresponding to both a delta lactate of 1 mM and an absolute lactate of 4 mM was significantly increased during the AAL (79.9 +/- 12.9 and 93.9 +/- 13.7% VO2max, respectively) compared with NAL (59.1 +/- 5.5 and 78.0 +/- 5.8% VO2max, respectively). These data suggest that strong relationships exist between the ventilatory and blood lactate response during AL exposure and altered acid-base states. Further, it is concluded that, unless the acid-base status is known, the use of an absolute or delta lactate value to compare submaximal exercise should be interpreted with caution.     

Adrenergic involvement in blood oxygen transport and acid-base balance during hypercapnic acidosis in the Rainbow Trout,Salmo gairdneri

Summary Rainbow trout (Salmo gairdneri) were subjected to 12 h of external hypercapnia (1% CO₂ in air) during - and/or -adrenoceptor blockade in order to assess the importance of adrenergic responses in modulating blood oxygen transport and acid-base balance during an acute acidotic stress. External hypercapnia caused an elevation of blood carbon dioxide tension and a reciprocal decrease in whole blood pH. A gradual elevation of blood bicarbonate levels caused whole blood pH to increase toward pre-hypercapnic values throughout the hypercapnic period. Pre-treatment of fish with propranolol (a -adrenoceptor antagonist) or phentolamine (an -adrenoceptor antagonist) did not affect their ability to regulate extracellular acid-base status during hypercapnia. On the other hand, adrenergic responses were essential in the maintenance of arterial blood oxygen content during hypercapnia despite the severe extracellular acidosis and a marked Root effect in trout blood, in vitro. Important adrenergic responses included pronounced increases in haematocrit (an -adrenergic effect) and arterial oxygen tension (- and -adrenergic effects) as well as partial regulation of red blood cell pH (a -adrenergic effect). Although pre-treatment of fish with either propranolol or phentolamine caused a reduction in blood oxygen content during hypercapnia, fish died only during complete adrenoceptor blockade, presumably due to severe hypoxemia.Symbols and abbreviations total concentration of oxygen or carbon dioxide, respectively - hct haemotocrit - rbc red blood cell     

The role of glucose,pyruvate and lactate in ATP production by rat spermatocytes and spermatids

The ATP content of pachytene spermatocytes and round spermatids, isolated from rat testes, was not maintained during incubation of the germ cells in the presence of glucose. Glucose was metabolized via glycolysis at a considerable rate, but the rate of oxidation of the resulting endogenous pyruvate in the mitochondria was too low to support fully ATP production. Exogenous pyruvate (0.25 mM) or exogenous l-lactate (3–6 mM), however, were effective energy substrates. The lactate dehydrogenase reaction in isolated germ cells favoured the rapid conversion of pyruvate to lactate, at the expense of reducing equivalents from mitochondrial NADH. Hence, to support ATP production by the germ cells via mitochondrial metabolism of endogenous pyruvate, a relatively high concentration of exogenous lactate may be essential. In the spermatogenic microenvironment in vivo, such high concentrations of lactate could result from the net production of lactate by Sertoli cells. The mitochondria of the isolated germ cells produced ATP probably at a close to maximal rate, and spermatogenesis therefore may be extremely sensitive to compounds which interfere with mitochondrial energy metabolism and respiratory control.     

The role of low-level lactate production in airway inflammation in asthma

Warburg and coworkers (Warburg O, Posener K, Negelein E. Z Biochem 152: 319, 1924) first reported that cancerous cells switch glucose metabolism from oxidative phosphorylation to aerobic glycolysis, and that this switch is important for their proliferation. Nothing is known about aerobic glycolysis in T cells from asthma. The objective was to study aerobic glycolysis in human asthma and the role of this metabolic pathway in airway hyperreactivity and inflammation in a mouse model of asthma. Human peripheral blood and mouse spleen CD4 T cells were isolated by negative selection. T cell proliferation was measured by thymidine incorporation. Cytokines and serum lactate were measured by ELISA. Mouse airway hyperreactivity to inhaled methacholine was measured by a FlexiVent apparatus. The serum lactate concentration was significantly elevated in clinically stable asthmatic subjects compared with healthy and chronic obstructive pulmonary disease controls, and negatively correlated with forced expiratory volume in 1 s. Proliferating CD4 T cells from human asthma and a mouse model of asthma produced higher amounts of lactate upon stimulation, suggesting a heightened glycolytic activity. Lactate stimulated and inhibited T cell proliferation at low and high concentrations, respectively. Dichloroacetate (DCA), an inhibitor of aerobic glycolysis, inhibited lactate production, proliferation of T cells, and production of IL-5, IL-17, and IFN-γ, but it stimulated production of IL-10 and induction of Foxp3. DCA also inhibited airway inflammation and hyperreactivity in a mouse model of asthma. We conclude that aerobic glycolysis is increased in asthma, which promotes T cell activation. Inhibition of aerobic glycolysis blocks T cell activation and development of asthma.     

Computational model of excitatory/inhibitory ratio imbalance role in attention deficit disorders

Impairments in attentional behaviors, including over-selectivity, under-selectivity, distractibility and difficulty in shift of attention, are widely reported in several developmental disorders, including autism. Uncharacteristic inhibitory to excitatory neuronal number ratio (IER) and abnormal synaptic strength levels in the brain are two broadly accepted neurobiological disorders observed in autistic individuals. These neurobiological findings are contrasting and their relation to the atypical attentional behaviors is not clear yet. In this paper, we take a computational approach to investigate the relation of imbalanced IER and abnormal synaptic strength to some well-documented spectrum of attentional impairments. The computational model is based on a modified version of a biologically plausible neural model of two competing minicolumns in IT cortex augmented with a simple model of top-down attention. Top-down attention is assumed to amplify (attenuates) attended (unattended) stimulus. The inhibitory synaptic strength parameter in the model is set such that typical attentional behavior is emerged. Then, according to related findings, the parameter is changed and the model's attentional behavior is considered. The simulation results show that, without any change in top-down attention, the abnormal inhibitory synaptic strength values - and IER imbalance- result in over-selectivity, under-selectivity, distractibility and difficulty in shift of attention in the model. It suggests that the modeled neurobiological abnormalities can be accounted for the attentional deficits. In addition, the atypical attentional behaviors do not necessarily point to impairments in top-down attention. Our simulations suggest that limited changes in the inhibitory synaptic strength and variations in top-down attention signal affect the model's attentional behaviors in the same way. So, limited deficits in the inhibitory strength may be alleviated by appropriate change in top-down attention biasing. Nevertheless, our model proposes that this compensation is not possible for very high and very low values of the inhibitory strength.     

The role of prostacyclin in the hypercapnic and hypoxic cerebrovascular dilations

The cerebral blood flow (CBF H/A) and the production of a stable prostacyclin metabolite, 6-Keto PGF 1 alpha ( 6KPGF ) was studied in 5 baboons in control, hypercapnic and hypoxic conditions. In steady-state conditions CBF H/A was measured by the clearance of an intra-arterial bolus injection of 133xenon and arterial and cerebral venous blood was sampled for assay of 6KPGF by radioimmunoassay. Both hypercapnia and hypoxia significantly increased CBF H/A and both increments were abolished by indomethacin. However, only hypoxia showed an increased 6KPGF production. Thus, hypoxia, but not hypercapnia, appears to produce cerebral vasodilation by increasing prostacyclin production.     

Culture of Plasmodium falciparum: the role of pH, glucose, and lactate

Yields of P. falciparum in intraerythrocytic in vitro cultures were maximized when extracellular pH was maintained between 7.2 and 7.45, and extracellular lactate was kept below 12 mM. Host erythrocytes metabolized 4.6 +/- 1.5 microM glucose/10(9) RBC/24 hr and produced 7.9 +/- 1.8 microM lactate/10(9) RBC/24 hr. Asynchronous parasite cultures used 122 +/- 34 microM glucose/10(9) parasitized RBC/24 hr and produced 143 +/- 47 microM lactate/10(9) parasitized RBC/24 hr. Synchronous cultures that were 80 to 100% ring forms after 24 hr in culture exhibited significantly lower glycolysis per 10(9) parasitized RBC than cultures that were 0 to 25% ring forms after 24 hr. The percent of glucose utilization accounted for by lactate production by parasites was significantly less than that of uninfected erythrocytes. These optimum ranges and metabolic rates can be used in the development of parasite culture techniques.     

Effects of NaHCO3 loading on acid-base balance, lactate concentration, and performance in racing greyhounds

This investigation examined the effects ofNaHCO₃ loading on lactateconcentration ([La]), acid-base balance, and performance for a 603.5-m sprint task. Ten greyhounds completed aNaHCO₃ (300 mg/kg body weight) andcontrol trial in a crossover design. Results are expressed as means ± SE. Presprint differences (P < 0.05) were found for NaHCO₃ vs.control, respectively, for blood pH (7.47 ± 0.01 vs. 7.42 ± 0.01), HCO₃ (28.4 ± 0.4 vs. 23.5 ± 0.3 meq/l), and base excess (5.0 ± 0.3 vs. 0.2 ± 0.3 meq/l). Peak blood [La] increased(P < 0.05) inNaHCO₃ vs. control (20.4 ± 1.6 vs. 16.9 ± 1.3 mM, respectively). Relative to control,NaHCO₃ produced a greater(P < 0.05) reduction in blood baseexcess (18.5 ± 1.4 vs. 14.1 ± 0.8 meq/l) andHCO₃ (17.4 ± 1.2 vs.12.8 ± 0.7 meq/l) from presprint to postexercise. Postexercise peak muscle H⁺concentration ([H⁺])was higher (P < 0.05) inNaHCO₃ vs. control (158.8 ± 8.8 vs. 137.0 ± 5.3 nM, respectively). Muscle[H⁺] recoveryhalf-time (7.2 ± 1.6 vs. 11.3 ± 1.6 min) and time to predosevalues (22.2 ± 2.4 vs. 32.9 ± 4.0 min) were reduced(P < 0.05) inNaHCO₃ vs. control, respectively.No differences were found in blood[H⁺] or blood[La] recovery curves or performance times.NaHCO₃ increased postexerciseblood [La] but did not reduce the muscle or blood acid-basedisturbance associated with a 603.5-m sprint or significantly affectperformance.