呼吸指数对急性胰腺炎的临床价值

呼吸指数(RI)是指肺泡一动脉氧分压差与动脉氧分压之比[P(A-a)O2／PaO2],是反映肺的通气、氧交换功能的一个简单而实用的指标。我们对106例经血气分析证实为低氧血症的急性胰腺炎患者进行RI研究,以探讨其临床价值。     

无创正压通气对急性肺水肿疗效的观察

目的观察无创正压通气对急性肺水肿低氧血症的疗效。方法选择15例心源性或非心源性急性肺水肿所致的低氧血症患者,进行无创正压通气,并行心电监护、有创动脉血压、血氧饱和度、呼吸频率、血气分析、尿量等指标的监测。结果15例急性肺水肿患者存活14例,死亡1例,抢救成功率93.33％。治疗2小时后患者由烦躁转入安静,心率、呼吸频率减慢,氧分压明显提高,通气前后比较P＜0.05。结论无创正压通气,通过调节压力支持和呼气末正压水平,可降低肺间质和肺泡的渗出水肿,促进肺泡复张,改善通气血流比率,有利于气体弥散,从而提高动脉氧分压和氧饱和度。     

俯卧位通气在心脏外科术后顽固性低氧血症中的应用及效果观察

目的:研究俯卧位通气在心脏外科术后顽固性低氧血症中的应用及疗效。方法:选取2014年1月~2015年6月入院诊治的行心脏外科手术后发生顽固性低氧血症患者62例作为研究对象,对其实行早期俯卧位通气,观察治疗前后患者呼吸参数与血流动力学指标变化。结果:不同时间节点患者的动脉血氧分压、吸入气氧浓度、氧合指数、呼吸指数、静态肺顺应性差异具有统计学意义(P0.05),而肺泡-动脉氧分压差则在不同时间无统计学意义(P0.05);俯卧位通气0.5,2 h与转为仰卧位1 h后动脉血氧分压、氧合指数与静态肺顺应性均较俯卧位前升高,而呼吸指数下降,差异有统计学意义(P0.05);且动脉血氧分压在改为仰卧位1 h后较之俯卧位通气0.5,2 h时下降差异有统计学意义(P0.05)。收缩压在不同时间不尽相同,且俯卧位0.5 h后较之俯卧位前显著升高(P0.05);心率与中心静脉压在各个时段的变化并不明显(P0.05)。结论:俯卧位通气对于心脏外科手术后顽固性低氧血症患者,可有效改善患者的氧合状况,同时对血流动力学并无不良影响。     

小儿急性呼吸衰竭的处理和护理（1）

呼吸衰竭是小儿常见的危重症，也是婴幼儿死亡的重要原因之一。由于呼吸系统或呼吸中枢原发或继发性病变引起通气或换气功能障碍，不能充分代偿机体对氧的需要，出现缺氧和二氧化碳潴留。临床上按血气分析变化可分为Ⅰ型呼吸衰竭（低氧血症），Ⅱ型呼吸衰竭（低氧血症伴高碳酸血症）。缺氧和二氧化碳潴留是呼吸衰竭的基本清理生理改变，通气功能障碍使肺泡与外界气体交换发生障碍，吸入肺泡的氧减少，动脉血氧分压降低，二氧化碳分压增加；换气功能障碍使得通气血流比例失调，弥散障碍从而使动脉氧分压降低。其主要的临床表现为紫组，以唇、…     

无创通气在急性左心衰合并低氧血症患者抢救中的临床价值

目的：评价无创机械通气在急性左心衰竭合并低氧血症抢救中的临床价值。方法：对28例急性左心衰合并低氧血症的患者在常规内科治疗同时加用无创性经面罩机械通气（NIV）治疗，观察无创通气（NIV）前后患者呼吸指标、肺气体交换与心率（HR）、平均动脉压（MAP）的变化。结果：28例患者均能耐受NIV治疗，无一例需要气管插管机械通气，临床症状明显改善，呼吸频率明显下降（P〈0．05）。与NIV治疗前相比，患者的动脉血中pH、氧分压（PaO2）、二氧化碳分压（PaCO2）、氧饱和度（SaO2）等指标明显改善，HR与MAP明显减慢（P〈0．05）。结论：经面罩NIV治疗急性左心衰时能迅速改善患者的症状和低氧血症，避免气管插管，是一种快速、安全、有效的方法。     

面罩压力支持通气对改善慢性阻塞性肺病患者夜间低氧血症的效果观察

目的：观察面罩压力支持通气对改善慢性阻塞性肺病患者夜间低氧血症的效果。通过双相正压通气（ＢｉＰＡＰ）治疗夜间低氧血症，改善患者心肺功能。方法：对２０例伴夜间呼吸紊乱和低氧血症的慢性阻塞性肺病（ＣＯＰＤ）患者进行未吸氧、鼻导管吸氧、双相正压（ＢｉＰＡＰ）面罩压力支持通气３种状况下的夜间动脉血氧饱和度（ＳａＯ２）、心率、呼吸指标的监测。结果：未吸氧状况下患者夜间低氧血症明显，ＳａＯ２≤０．７２；ＢｉＰＡＰ面罩压力支持通气时ＳａＯ２的升高明显优于鼻导管吸氧，ＳａＯ２＞０．８５（Ｐ＜０．００１）。结论：ＢｉＰＡＰ面罩压力支持通气对改善ＣＯＰＤ患者夜间睡眠和呼吸紊乱，纠正低氧血症有明显作用。     

重型颅脑损伤患者院前转运中的呼吸机应用和护理探讨

正急救转运通常包含急危重症患者院前、院内监护抢救和院外运送过程,由于重型颅脑损伤患者病情变化迅速,肺通气功能不良,转运过程中易出现低碳酸血症和动脉氧分压[p(O2)]持续降低,引起脑血管痉挛,影响后续治疗,因此建立有效的人工气道,纠正低氧和低碳酸血症是保证抢救成功的重要环节[1]。相比于传统的气囊面罩通气,应用转运呼吸机能避免供氧有限的危险,稳定患者潮气量和呼吸频率,维持有效通气[2]。目     

无创双水平正压通气在OPCAB术后低氧血症中的应用及护理体会

目的探讨无创双水平正压通气在不停跳冠状动脉旁路移植（OPCAB）术后低氧血症中的应用及护理。方法对21例拔除气管插管后出现低氧血症的OPCAB患者在第一时间予无创双水平正压通气（BIPAP）治疗,记录上机前、上机后6h的呼吸频率、心率、动脉收缩压、血氧饱和度、氧分压,对数据采用小样本的t检验。结果 21例患者上机前后两组观察指标统计学比较,P〈0.05,差异有统计学意义。结论 BIPAP的使用能有效纠正OPCAB术后出现的低氧血症,避免了气管插管带来的一系列并发症,因此对于术后已经拔除气管插管出现低氧血症的患者,建议早期应用双水平正压无创通气。     

呼吸指数对急性胰腺炎的临床价值

呼吸指数（RI）是指肺泡气-动脉氧分压差与动脉氧分压之比[（A－aDO2）／PaO2）],是反映肺的通气、氧交换功能的一个简单而实用的指标。我们对54例急性胰腺炎经血气分析证实为低氧血症的患者进行RI研究,探讨其临床价值。1资料与方法1．1一般资料本组男21例,女33例;年龄24～76岁,平均年龄47．5岁。诊断据1992年亚特兰大国际会议分类法[1]分为轻型、重型,其中轻型37例,重型17例。原均无心肺疾患。另同期选择20例临床免低氧表现、心肺功能正常者作对照组。1．2方法患者入院后采吸氧前常规取股动脉血,用美国IL公司产1312型自动血气…     

全麻术后患者鼻塞给氧效果的观察

为防止全麻术后机械通气撤机后的低氧血症，应合理使用氧疗。对术前通气功能正常的患者，可给予鼻塞吸氧，３Ｌ／ｍｉｎ，氧分压及二氧化碳分压均可达到满意的效果。     

Unreliability of oxygen tension-based indices in reflecting intrapulmonary shunting in critically ill patients

Measurement of intrapulmonary shunting (Qsp/Qt), a widely used method for monitoring disturbances of pulmonary oxygen transfer in critically ill patients, involves calculation of arterial and mixed venous oxygen contents. In circumstances where mixed venous blood samples are not readily available, oxygen tension-based indices such as the alveolar to arterial oxygen tension differences (P[A-a]O2), arterial oxygen tension to alveolar oxygen tension ratio (PaO2/PAO2), PaO2 to FIO2 ratio (PaO2/FIO2) and respiratory index (RI) are widely utilized to reflect Qsp/Qt. Oxygen content-based indices such as the estimated shunt are not as widely utilized as the oxygen tension indices. In 75 critically ill patients in whom a pulmonary artery catheter was being utilized to augment clinical care, comparisons were made between Qsp/Qt and P(A-a)O2, PaO2/PAO2, PaO2/FIO2, RI, and estimated shunt to determine which index best reflected Qsp/Qt. Correlations between Qsp/Qt and estimated shunt were good (r = .94) and poor for the P(A-a)O2 (r = .62), PaO2/PAO2 (r = .72), PaO2/FIO2 (r = .71), and RI (r = .74). We conclude that there are no real substitutes for venous oxygen contents in critically ill patients. When pulmonary artery blood is not available for analysis, oxygen tension-based indices are unreliable reflectors of Qsp/Qt while the estimated shunt, an oxygen content-based index, provides a more reliable reflection of Qsp/Qt.     

Respiratory index/pulmonary shunt relationship: quantification of severity and prognosis in the post-traumatic adult respiratory distress syndrome

The relationship between the respiratory index (RI = alveolar-arterial oxygen gradient [P(A-a)O2] normalized by PaO2) and the pulmonary shunt (Qsp/Qt) has been examined in 929 studies from 240 critically ill post-traumatic patients. Of these, 88 patients (443 studies) were individuals who developed post-traumatic adult respiratory distress syndrome (ARDS) and 152 were patients (486 studies) who did not develop ARDS. This study demonstrates that the RI to Qsp/Qt [RI/(Qsp/Qt)] relationship was significantly (p less than .0001) increased in patients who developed fatal ARDS compared with those who did not develop ARDS, or with those whose ARDS resolved. Because of the increased oxygen consumption (VO2) in ARDS patients in association with their severe limitations in gas exchange (RI) and increased Qsp/Qt, surviving ARDS patients had a significant increase in the cardiac index which resulted in a higher oxygen delivery to VO2 ratio. ARDS patients showed significant (p less than .0001) evidence of increased pulmonary vascular tone, correlated with the increase in the RI/(Qsp/Qt) relationship. In addition, those patients with high RI/(Qsp/Qt) also had increased right ventricular (RVSW) to left ventricular work (LVSW) ratios which were shown to be a direct function of the rise in RI. This increase in both RVSW/LVSW and RI/(Qsp/Qt) ratios was significantly (p less than .0001) correlated with an increased mortality. Thus, the RI/(Qsp/Qt) relationship, which can be obtained from arterial and mixed venous blood gases and saturations only, can be used to predict the severity of the ARDS process as well as important pulmonary vascular and right ventricular overload consequences.     

The impact of arterial oxygen tension on venous oxygen saturation in circulatory failure

Central and mixed venous oxygen saturations have been used to guide resuscitation in circulatory failure, but the impact of arterial oxygen tension on venous oxygen saturation has not been thoroughly evaluated. This observational study investigated the impact of arterial oxygen tension on venous oxygen saturation in circulatory failure. Twenty critically ill patients with circulatory failure requiring mechanical ventilation and a pulmonary artery catheter in an intensive care unit in a tertiary hospital in Western Australia were recruited. Samples of arterial blood, central venous blood, and mixed venous blood were simultaneously and slowly drawn from the arterial, central venous, and pulmonary artery catheter, respectively, at baseline and after the patient was ventilated with 100% inspired oxygen for 5 min. The blood samples were redrawn after a significant change in cardiac index (>or =10%) from the baseline, occurring within 24 h of study enrollment while the patient was ventilated with the same baseline inspired oxygen concentration, was detected. An increase in inspired oxygen concentration significantly increased the arterial oxygen tension from 12.5 to 38.4 kPa (93.8-288 mmHg) (mean difference, 25.9 kPa; 95% confidence interval [CI], 7.5-31.9 kPa; P < 0.001) and the venous oxygen saturation from 69.9% to 76.5% (mean difference, 6.6%; 95% CI, 5.3% - 7.9%; P < 0.001). The effect of arterial oxygen tension on venous oxygen saturation was more significant than the effect associated with changes in cardiac index (mean difference, 2.8%; 95% CI, -0.2% to 5.8%; P = 0.063). In conclusion, arterial oxygen tension has a significant effect on venous oxygen saturation, and this effect is more significant and consistent than the effect associated with changes in cardiac index.     

Extrapulmonary factors influencing the ratio of arterial oxygen tension to inspired oxygen concentration in burn patients.

The ratio of arterial oxygen tension to inspired oxygen concentration (PaO2/FIO2) as an index of respiratory function was evaluated in 22 patients with body surface area burns of 15--80%. These results indicate that this ratio is limited in its applicability because extrapulmonary factors, such as cardiac output, oxygen consumption, and arterial oxygen content, can affect this index by alterations in the amount of venous desaturation. Useful estimates of intrapulmonary right to left shunt (Qs/Qt) from PaO2/FIO2 were obtained only when arteriovenous oxygen content differences (avDO2) were between 3--5 ml/dl. There were avDO2 values above and below 3--5 ml/dl in at least 35% of the observations. Under these circumstances, PaO2/FIO2 did not correctly reflect changes in Qs/Qt. Blood gases from central venous catheters did not mirror changes in true mixed venous blood and, thus, can lead to erroneous estimations of Qs/Qt. Rational therapy of reduced arterial oxygen saturation requires measurement of both extra- and intrapulmonary factors contributing to arterial desaturation. Measurement of PaO2/FIO2 alone will not estimate these factors.     

Effects of hyperventilation on conjunctival oxygen tension in humans

A polarographic conjunctival oxygen sensor was used to measure oxygen tension in a tissue bed supplied by the internal carotid artery. The shared vascular source of the conjunctiva and brain suggests that conjunctival PO2 monitoring may provide an index of cerebral perfusion. We studied the effects of hyperventilation, a known stimulus of cerebral vasoconstriction, on conjunctival oxygen tension (PcjO2) in six normal, healthy adults; arterial blood gases were simultaneously measured in four of these subjects. A 5-min period of hyperventilation to a PaCO2 near 20 torr resulted in a rapid and significant (p less than .01) increase in systemic oxygen tension as measured by arterial blood gases and a transcutaneous oxygen monitor. These values gradually returned to baseline upon cessation of hyperventilation. PcjO2, however, decreased significantly (p less than .01) during hyperventilation, suggesting vasoconstriction of the conjunctival vascular supply. Because these changes temporally correlate with the cerebral vasoconstriction during hyperventilation, the conjunctival index of tissue oxygen tension may correlate with cerebral perfusion.     

Effect of normobaric hyperoxia on parameters of brain metabolism

In the literature there is only little information about the influence of hyperoxia on cerebral metabolic parameters. The aim of our study was to examine the effect of increased inspiratory oxygen concentrations on parameters of brain metabolism in elective neurosurgical patients. Ten patients undergoing an elective craniotomy for brain tumour resection were included in the study. The inspiratory oxygen concentration was raised at intervals of 15 minutes from 0.4 to 0.6 to 1.0 before opening the skull under "relative steady state conditions". At five defined measuring points, a blood gas analysis and an analysis of lactate and glucose levels were performed from arterial and jugularvenous blood. The lactate oxygen index (LOI), the arterio-jugularvenous lactate difference (AJDL) and the oxygen content of the arterial (caO2) and jugularvenous (cjO2) blood were calculated. Under increasing levels of FiO2, one can see an increase in sjO2, of jugularvenous oxygen tension (pjO2) and in oxygen content (cjO2). The most important result is the significant decrease (10% from baseline) in jugularvenous lactate at FiO2 1.0, while arterial lactate did not change significantly nor did the following parameters: paCO2, pjCO2, LOI, modified LOI, arterial and jugularvenous glucose. Hyperoxia causes a possible shift to aerobic metabolic situation in the brain reflected by decreased jugularvenous lactate.     

Lactic acidemia in baboons after transfusion of red blood cells with improved oxygen transport function and exposure to severe arterial hypoxemia

Baboons were bled one-third of their blood volume and then transfused with an equivalent volume of compatible donor red blood cells with 160 per cent of normal 2,3-diphosphoglycerate (2,3-DPG) levels and improved capacity to release oxygen to tissue. The mixture of baboon donor- recipient red blood cells in the circulation had a 2,3-DPG level of 130 per cent of normal. After transfusion, the baboon's inspired oxygen was first lowered from 21 to 10 per cent to produce severe arterial hypoxemia with a PO2 tension of less than 40 mm Hg for two hours and then restored to 21 per cent. Lactic acidemia occurred when the alveolar oxygen tension was reduced so as to produce an arterial oxygen tension of less than 40 mm Hg, even though oxygen consumption was maintained. The data suggest that when red blood cells with normal or improved oxygen delivering capacity are transfused to patients, the alveolar oxygen tension should be sufficient to maintain an arterial oxygen tension of greater than 40 mm Hg.     

高血压患者肾动脉阻力指数变化的临床意义

目的了解高血压患者肾动脉阻力指数(resistive index,RI)的变化及其临床意义.方法选择肾功能处于不同阶段的原发性高血压患者142例,对照组15例.用彩色多普勒超声仪测量肾动脉RI.结果高血压慢性肾功能不全(CRI)代偿期和失代偿期患者各级肾动脉RI(0.77～0.81)均明显高于高血压肾功能正常组和对照组(0.69～0.71), 差异有统计学意义(均P<0.01).高血压2级和高血压3级患者的各级肾动脉RI均较对照组升高,尤以肾主动脉RI增高为著(P<0.05～<0.01).相关分析表明,肾动脉RI与血尿素氮(BUN)和血肌酐(Scr)呈正相关关系、与肌酐清除率(Ccr)呈负相关关系;肾动脉RI与收缩压最高值正相关(r=0.168, P<0.05);肾动脉RI与年龄正相关(r=0.44,P<0.01).结论肾动脉RI与高血压患者的肾功能状态、血压及年龄相关;肾动脉RI可作为评估肾功能损害程度的指标.     

Oxygen tensions and oxyhemoglobin saturations in the assessment of pulmonary gas exchange

We studied the theoretical basis for continuous monitoring of pulmonary gas exchange using arterial and mixed venous oximetry by examining the mathematical relationships between the calculated venous admixture (Qsp/Qt) and the ventilation-perfusion index, which is derived from oxyhemoglobin saturations. We compared this relationship with that between Qsp/Qt and its commonly used estimates: inspired oxygen concentration to arterial blood oxygen tension ratio, arterial to alveolar oxygen tension ratio, and alveolar-arterial oxygen tension difference. The relationship between Qsp/Qt and the oxygen tension-based indices is nonlinear and substantially influenced by changes in inspired oxygen concentration and arteriovenous oxygen content difference. Therefore, it is inaccurate within the clinically acceptable range of arterial blood oxygenation. In contrast, calculation of ventilation-perfusion index from arterial and mixed venous blood oxyhemoglobin saturations provides a linear estimate of Qsp/Qt that is minimally affected by alterations in inspired oxygen concentration or oxygen uptake and, therefore, will allow accurate continuous assessment of pulmonary gas exchange.     

Estimation of changes in alveolar-arterial oxygen gradient induced by hypoxia

The alveolar-arterial oxygen tension difference provides a useful clinical indication of ventilation-blood flow mismatching in the lungs. In some clinical situations involving alveolar hypoxia (e.g., patients with chronic obstructive lung disease flying in commercial aircraft or normal humans at high altitudes) it would be useful to know this tension difference to predict the likely arterial PO2 under such potentially stressful conditions. Such estimates would require multiple arterial punctures performed under a variety of trying circumstances, conditions usually far distant from a suitable analytic facility. Consequently, we induced controlled hypoxia in 23 healthy humans and calculated changes in the alveolar-arterial oxygen tension difference during the hypoxic challenge test. We plotted this difference as a function of the alveolar oxygen tension over a range from 35 to 110 mm Hg. In addition to a series of control studies in which multiple arterial blood samples were obtained, we calculated arterial PO2 by converting the arterial oxyhemoglobin saturation (measured with an ear oximeter) into partial pressure of oxygen. During hypoxic procedures in which levels of oxygenation fell on the steep section of the oxyhemoglobin dissociation curve, fixing PCO2 at constant predetermined levels allowed accurate predictions of arterial PO2. We were able to demonstrate that the alveolar-arterial oxygen tension difference narrowed with decreasing alveolar oxygen tension, and that measurement with an ear oximeter provided data that allowed a reasonable estimate of the tension difference during hypoxic conditions.