Effect of heparin on arterial blood gases

To evaluate changes in arterial blood gas samples caused by the addition of liquid heparin, 50 patients had three simultaneous blood samples drawn, each with one of three amounts of heparin. The liquid heparin decreased statistically the PCO2, PO2, HCO3, and base excess, while the pH remained unchanged. By using a 2-cc blood sample with a 5-cc glass syringe and a 11/2-inch, 18-gauge needle to draw the heparin solution up to the 2-cc mark, and then completely evacuating it, we found that 0.025 cc of solution remained to coat the syringe. Although this remaining solution would cause a 1.25% error in the blood gas results, the error would be acceptable because it is generally less than the standard deviation of the laboratory results. Excess liquid heparin statistically exaggerated or produced false results consistent with a metabolic acidosis with respiratory compensation. We recommend that the complete evacuation of liquid heparin from the sampling syringe be included when performing an arterial blood gas analysis.     

Prognostic implications of arterial blood gases in acute decompensated heart failure

Background

The prognostic value of arterial blood gases (ABG) in patients with acute decompensated heart failure (ADHF) is not well-established. We therefore conducted the present study to determine the relationship between ABG on admission and long-term mortality in patients with ADHF.

Methods

We studied 588 patients consecutively admitted to our department with ADHF. ABG and classical prognostic variables were determined at patients' arrival to the emergency department. The independent association among the main variables of ABG (pO2, pCO2 and pH) and mortality was assessed with Cox regression analysis.

Results

At a median follow-up of 23 months, 221 deaths (37.6%) were registered. 308 (52.4%), 54 (9.2%) and 50 (8.5%) patients showed hypoxemia (pO2 < 60 mm Hg), hypercapnia (pCO2 > 50 mm Hg) and acidosis (pH < 7.35), respectively. Patients with hypoxemia, hypercapnia and acidosis did not show higher mortality rates (38% vs. 37.1%, 42.6% vs. 37.1%, and 48% vs. 36.6%, respectively; p-value = ns for all comparisons). In multivariate analysis, after adjusting for well-known prognostic covariates, pO2, pCO2 and pH did not show a significant association with mortality. Hazard ratios (HR) for these variables were: pO2, per increase in 10 mm Hg: 0.99 (95% CI: 0.90–1.09), p = 0.861; pCO2, per increase in 10 mm Hg: 1.12 (95% CI: 0.91–1.39), p = 0.262; pH per increase in 0.1: 1.01 (95% CI: 0.99–1.04), p = 0.309. When dichotomizing these variables according to established cut-points, the HR were: hypoxemia (pO2 < 60 mm Hg):1.07 (95% CI: 0.81–1.40), p = 0.637; hypercapnia (pCO2 > 50 mm Hg): 0.98 (95% CI: 0.62–1.57), p = 0.952; acidosis (pH < 7.35): 1.38 (95% CI: 0.87–2.19), p = 0.173.

Conclusion

In patients admitted with ADHF, admission arterial pO2, pCO2 and pH were not associated with all-cause long-term mortality.     

Use of peak expiratory flow rates to eliminate unnecessary arterial blood gases in acute asthma

Arterial blood gas (ABG) measurements are used frequently in acute asthma. Because ABGs are expensive and may have significant side effects, a method is needed to identify those patients at risk for a significantly abnormal ABG. We studied the use of peak expiratory flow rates (PEFR) to identify those patients at such risk. Data from 89 emergency visits by 51 asthmatic patients were analyzed. A small but significant correlation between ABG parameters and PEFR was observed (P less than 0.05). No patient with a PEFR greater than or equal to 25% predicted has a PaCO2 greater than 45 mm Hg or pH less than 7.35. This suggests that only those patients with a PEFR less than 25% predicted are at risk for significant hypercarbia or acidosis. We concluded that PEFR may be used as a simple screening tool to safely eliminate ABGs in at least 40% of acute asthmatic patients.     

肺性脑病与动脉血气参数关系的临床研究

目的研究肺性脑病的发生及临床症状的严重程度与动脉血气参数的关系。方法研究110例慢性肺源性心脏病并2型呼吸衰竭患者和其中53例发生有肺性脑病患者的血气参数及53例肺性脑病患者中按意识障碍严重程度分组的血气参数。结果动脉血PaCO2>80 mmHg同时PaO2<50 mmHg,肺性脑病的发生率明显增高(92.85%),动脉血PaCO2>80 mmHg同时pH<7.2,肺性脑病的发生率为100%。患者血气的PaCO2上升及pH、PaO2下降速度越快,患者的意识障碍程度越重。结论动态观察血气分析参数有助于防治肺性脑病和改善其临床预后。     

A comparison of arterial and non-arterialized capillary blood gases in diabetic ketoacidosis

The results of acid-base and blood gas estimations in arterial and non-arterialized capillary blood have been compared in samples obtained simultaneously from patients presenting with diabetic ketoacidosis. Highly significant correlations were obtained for pH, pCO2 and bicarbonate measurements. Small but significant differences were observed with capillary pH slightly lower and capillary pCO2 and bicarbonate slightly higher than arterial values. These differences were of no clinical significance. Non-arterialized capillary samples are a reliable indicator of acid-base status in this form of metabolic acidosis and are preferable to repeated arterial puncture.     

Comparison of central venous and arterial pH and PCO2 during open-chest CPR in the canine model

Arterial blood gases are difficult to obtain during cardiopulmonary resuscitation (CPR) in human beings, and the possibility of venous sampling is raised frequently. The reliability of central venous gases as a substitute for arterial blood gases in assessing acid base status, however, has not been investigated adequately under conditions of CPR. Therefore, femoral arterial and central venous catheters were placed in 24 mongrel dogs, and ventricular fibrillation was electrically induced. After varying predetermined downtimes from five to 60 minutes, open-chest CPR was begun, and arterial and central venous blood gases were simultaneously drawn every five minutes during a 30-minute period. Arterial pH (pHa) was consistently higher than central venous pH (pHcv) by an average of .048 units. A significant correlation existed between the pHa and pHcv at all times during CPR, with an overall r = .9771 (P less than .0001). The difference between central venous PCO2 (PcvCO2) and arterial PCO2 (PaCO2) was 5.17 mm Hg prior to cardiac arrest, but it increased 300% to a mean of 15.51 mm Hg during CPR. Correction of pHcv using conventional methods to account for this respiratory component decreased the correlation between pHa and pHcv to r = .6905. The ability of pHcv to substitute for pHa was assessed, and showed a sensitivity of 100% when pHa of 7.2 was used as a criterion for treatment. In this model, pHcv is a sensitive indicator of pHa and it may be used to guide bicarbonate therapy. The increased PcvCO2 during CPR probably results from the marked tissue lactic acid production and subsequent shift of the bicarbonate buffer into free carbon dioxide.     

Partitioning the respiratory effects of airway citric acid and normal saline in lambs

Aspiration is common in the intubated human neonate. Thus, the ventilatory and blood gas responses to citric acid and saline instillation into different airway sites were studied in ten awake, unanesthetised lambs, breathing spontaneously via a tracheostomy tube. With a system of balloons, 1 ml of saline or citric acid was placed selectively into the midtrachea, the laryngeal area, or the lower trachea (lower tr). Changes in minute ventilation (VE), after a 30 sec baseline period, were measured 30 sec and 1 and 2 min after the challenge. Arterial blood gas changes were measured at 30 sec and 2 min. Major increases in VE were seen only when saline or citric acid was instilled into the lower tr, the citric acid responses exceeding saline ones. The arterial oxygen tension (PaO2) fell after lower tr saline, whereas the arterial CO2 tension (PaCO2) fell with midtracheal saline instillation. A rise in pH and a fall in PaCO2 accompanied citric acid given into the lower tr. An initial rise in PaO2 after citric acid into the lower tr was followed by a return to baseline despite hyperventilation. The ventilatory and blood gas changes with saline and citric acid depend on the site of airway instillation.     

Studies on the regulation of myocardial blood flow in man II. Effects of acute arterial hypoxia

To determine whether adjustment of myocardial blood flow (MBF), myocardial oxygen consumption (MVO₂) and myocardial substrate uptake (MSU) to acute arterial hypoxia is influenced by training effects on the heart, 7 trained and 7 untrained healthy individuals were investigated. MBF (argon method), MVO₂ and MSU of glucose, lactate and free fatty acids were measured at rest during normoxia and two different stages of acute arterial hypoxia: a) 12.82 vol% O₂; b) 8.74 vol% O₂. Measurements were carried out during hemodynamic and respiratory steady state conditions. Myocardial flow and metabolism of athletes were significantly (p<0.01) lower compared to untrained subjects. In the trained cohort, MBF increased from 65 ± 19 to 73 ± 16 (a) and 98 ± 23 (b) ml/min·100 g. MVO₂ remained at normoxic control level of 8.00 ± 2.27 ml/min·100g. In the untrained group, MBF increased from 77 ± 15 to 84 ± 20 (a) and 108 ± 18 (b) ml/min · 100g. Again, there was no significant deviation in MVO₂ from the normoxic level of 10.11 ± 1.90 ml/min·100g. Decrease in arterial oxygen content was overcompensated by an increase in coronary conductance resulting in a significantly improved efficiency of myocardial perfusion during severe hypoxia. MSU of glucose, lactate and free fatty acids as well as calculated ATP production did not change significantly during hypoxia. It is concluded that training effects on the heart do not influence regulation of MBF, MVO₂ and MSU during moderate or severe acute arterial hypoxia. Reaction of coronary smooth muscle tone to a decrease in oxygen partial pressure is independent from training effects. However, both acute arterial hypoxia and physical training exert synergetic effects on the heart by reducing myocardial oxygen consumption per heart beat. Thus, it is assumed that adaptive properties of myocardial blood flow and metaboüsm to severe hypoxia are more pronounced in trained than in untrained individuals.     

Comparison of deep and shallow endotracheal administration of dionosil in dogs and effect of manual hyperventilation

The endotracheal route has been used as a second route of choice for administration of emergency drugs for several years; however, the optimal technique for administration of drugs by this route has not been clearly defined. One important aspect of technique involves the question of how distribution to the distal-most endobronchial tree is influenced by initial depth of endotracheally administered drug instillation and use of forced manual hyperventilation. This study demonstrates that depth of instillation of drugs administered by the endotracheal route may not be an important factor in the delivery of medications to absorptive sites in the lung. It appears, however, that forced manual hyperventilation is essential to assure bilateral and optimal distal delivery of endotracheally administered medications.     

Exhalation time effects on arterial and venous blood oxygen content and arterial PCO2 during high frequency jet ventilation of surfactant-depleted cats

Since high frequency jet ventilation (HFJV) relies on lung mechanics for the passive removal of expiratory gas, one would predict that the time allowed for exhalation would have serious effects on cardiopulmonary function. To document these effects we lavaged the lungs of ten cats with 30 ml/kg of saline six times, then sampled arterial and venous blood while the animals were ventilated conventionally at 30 BPM and then with HFJV at 600 BPM, varying inspiratory/expiratory ratios (I/E) from 1:1 to 1:5. The animals breathed 100% O2 throughout the study, and the mean airway pressure was held constant for each animal when the I/E was varied during HFJV. Decreasing the I/E from 1:1 to 1:5 during HFJV resulted in an increase of arterial oxygen content (Cao2) from 11.3 +/- 1.2S E to 13.6 +/- 1.2 ml O2/100 ml blood (P less than 0.01), a decrease of PaCO2 from 43 +/- 6 to 27 +/- 4 mm Hg, and an increase of alveolar to arterial oxygen gradient from 351 +/- 49 to 377 +/- 49 mm Hg. The ratio of systemic blood flow to oxygen consumption (Q/VO2) was similar during conventional ventilation and with HFJV at I/E of 1:1 (18.9 +/- 3.7 vs 18.0 +/- 2.9) but decreased when I/E was reduced to 1:5 during HFJV (13.9 +/- 2.1). The ratio of the product of CaO2 and Q (systemic oxygen availability) to VO2 (SO2 T/VO2) remained unchanged during all modes of ventilation (1.75 +/- 0.15). The increase in CaO2 observed when I/E was reduced from 1:1 to 1:5 during HFJV was counterbalanced by a decrease in Q/VO2 such that SO2 T/VO2 remained relatively constant.     

非糖尿病人群空腹血糖水平对动脉僵硬度进展的影响

目的 探讨非糖尿病人群基线空腹血糖水平与动脉僵硬度进展的关联.方法 本研究选取了在2010-2018年完成了两次臂踝动脉脉搏波传导速度(baPWV)测量且第一次baPWV测量时为非糖尿病的开滦研究队列人群作为观察对象.采用多元线性回归方法,分析基线空腹血糖对随访baPWV和随访期间baPWV进展的影响.结果 符合纳入标...     

Regulation of hepatic blood flow: the hepatic arterial buffer response revisited

The interest in the liver dates back to ancient times when it was considered to be the seat of life processes. The liver is indeed essential to life,not only due to its complex functions in biosynthesis,metabolism and clearance,but also its dramatic role as the blood volume reservoir. Among parenchymal organs,blood flow to the liver is unique due to the dual supply from the portal vein and the hepatic artery. Knowledge of the mutual communication of both the hepatic artery and the portal vein is essential to understand hepatic physiology and pathophysiology. To distinguish the individual importance of each of these inflows in normal and abnormal states is still a challenging task and the subject of on-going research. A central mechanism that controls and allows constancy of hepatic blood flow is the hepatic arterial buffer response. The current paper reviews the relevance of this intimate hepatic blood flow regulatory system in health and disease. We exclusively focus on the endogenous interrelationship between the hepatic arterial and portal venous inflow circuits in liver resection and transplantation,as well as inflammatory and chronic liver diseases. We do not consider the hepatic microvascular anatomy,as this has been the subject of another recent review.     

全反式维甲酸治疗对大鼠肺气肿动脉血气变化的研究

目的观察研究不同浓度全反式维甲酸（ATRA）对猪胰蛋白酶（PPE）构建的大鼠肺气肿动脉血气变化的情况。方法 60只Wistar大鼠随机分为对照组（N）和模型组（E）,棉籽油组（C）,小剂量ATRA治疗组（L）,中剂量ATRA治疗组（M）,大剂量ATRA治疗组（H）,每组各10只,一次性气管内注入PPE构建大鼠肺气肿模型后,用大、中、小剂量ATRA和棉籽油注入大鼠腹腔内进行治疗。30天后测量大鼠体重,动脉血气分析。结果 L组大鼠动脉血气分析较E组有显著改善（P〈0.05）,接近N组水平;C、M、H组动脉血气未见明显效果,且有缺氧明显趋势。结论低剂量ATRA治疗大鼠肺气肿对改善动脉血气具有较好的效果。     

动脉血乳酸和C-反应蛋白对重症肺炎预后的评估价值

目的探讨C-反应蛋白和动脉血乳酸在重症肺炎患者预后评价中的价值。方法分析我院重症医学科住院的重症肺炎患者的临床资料。结果 70例患者被纳入本研究,死亡28例,好转42例。C-反应蛋白的ROC曲线下面积0.718(95%可信区间:0.599～0.836,P=0.005),C-反应蛋白9 mg/dl时Youden指数最大,为0.464。动脉血乳酸的ROC曲线下面积0.699(95%可信区间:0.573～0.825,P=0.005),血乳酸2.4mmol/L时Youden指数最大,为0.333。Logistc回归分析显示:血乳酸>2.4 mmol/L死亡风险上升(OR 3.333;95%CI 0.226～49.093);C反应蛋白>9 mg/dl死亡风险更高(OR 9.0;95%CI 1.628～49.756);C反应蛋白>9 mg/dl同时血乳酸>2.4 mmol/L死亡风险最高(OR 17.778;95%CI 3.356～94.179)结论 C-反应蛋白和动脉血乳酸同时升高的重症肺炎患者较单独一项升高的患者有更高的死亡风险。     

COPD患者经皮血气参数与动脉血气参数的相关性及影响因素的分析

目的研究慢性阻塞性肺疾病（COPD）患者经皮二氧化碳分压（TcPaCO2）、经皮氧分压（TcPO2）及经皮血氧饱和度（SpO2）与动脉血气参数的相关性和影响因素，探讨其临床应用价值。方法测定31例COPD缓解期患者的TcPCO2、TrPO2及SpO2，同步测定动脉血气参数和进行肺功能参数测定。结果①COPD患者经皮血气参数与动脉血气参数间存在线性相关关系，其相关系数和回归方程如下：TcPCO2和PaCO2（Y=3．967＋0．941X，r=0．846，P〈0．001）、TcPO2和PaO2（Y=33．502＋0．716X，r=0．602，P〈0．001）、SpO2和SaO2（Y=7．639＋0．941X，r=0．763，P〈0．001）。②年龄及肺功能参数不是影响COPD患者TcPCO2、TcPO2及SpO2的因素。结论COPD患者经皮血气参数与动脉血气参数间有较好的相关性，经皮血气参数可作为一种无创监测手段应用于临床。