预充氧对减少吸痰导致组织缺氧的临床观察

为研究预充氧对吸痰导致组织缺氧的影响,在非预充氧和预充氧条件下,观察１４ 例危重患者吸痰前、吸痰结束时、吸痰后５ 分钟动脉血气和混合静脉血气的变化。结果：与吸痰前相比,非预充氧组吸痰结束时的动脉血氧分压（ＰａＯ２） 、动脉血氧饱和度（ＳａＯ２）、混合静脉血氧分压（ＰｖＯ２）、混合静脉血氧饱和度（ＳｖＯ２） 均显著降低（ Ｐ＜０．０５）,吸痰结束后５ 分钟,ＳｖＯ２ 仍未恢复正常。如给予预充氧,吸痰结束时无低氧血症,组织缺氧较轻,虽然ＰａＯ２ 、ＳａＯ２ 、ＰｖＯ２ 、ＳｖＯ２ 亦低于吸痰前水平,但明显高于非预充氧组吸痰结束时的水平。吸痰结束后５ 分钟,组织缺氧完全纠正。结论：预充氧可以预防吸痰导致的低氧血症和组织缺氧。     

浅层吸痰对机械通气新生儿血氧饱和度影响的研究

[目的]比较浅层吸痰及常规吸痰对机械通气新生儿血氧饱和度(SpO2)的影响,探讨最佳的吸痰方式.[方法]采用浅层吸痰法,即吸痰管的前端不超过人工气道的长度,并在吸痰前、吸痰结束时及吸痰结束后2 min记录新生儿的血氧饱和度.[结果]浅层吸痰法吸痰结束时及吸痰结束后2 min的血氧饱和度均高于常规吸痰(P<0.05).[结论]采用浅层吸痰能有效提高机械通气新生儿的血氧饱和度.     

浅层吸痰对机械通气新生儿血氧饱和度影响的研究

[目的]比较浅层吸痰及常规吸痰对机械通气新生儿血氧饱和度（SpO2）的影响,探讨最佳的吸痰方式。[方法]采用浅层吸痰法,即吸痰管的前端不超过人工气道的长度,并在吸痰前、吸痰结束时及吸痰结束后2min记录新生儿的血氧饱和度。[结果]浅层吸痰法吸痰结束时及吸痰结束后2min的血氧饱和度均高于常规吸痰（P〈0.05）。[结论]采用浅层吸痰能有效提高机械通气新生儿的血氧饱和度。     

实施浅层吸痰对机械通气新生儿的疗效观察

目的比较浅层吸痰与传统吸痰对机械通气新生儿心率、血氧饱和度及吸痰后刺激的影响,探讨最佳的吸痰方式。方法两组新生儿分别采用传统吸痰法和浅层吸痰法吸痰,并比较吸痰前1min、吸痰结束时及吸痰后1min、2min、3min新生儿的心率、血氧饱和度和呛咳发生率。结果浅层吸痰法新生儿心率、血氧饱和度在吸痰前后均无明显变化,未发生呛咳;吸痰结束时及吸痰结束后1min、2min两组新生儿的心率、血氧饱和度差异均具有统计学意义(P<0.01)。结论采用浅层吸痰能有效保持机械通气新生儿的心率、血氧饱和度的平稳和有效减少呛咳。     

气管切开患者吸痰前不同浓度氧疗效果比较

目的：探讨气管切开患者在吸痰前提高不同氧浓度对患者血氧饱和度的影响。方法：吸痰前提高患者的氧流量为5L／min、6L／min、7L／min分别为2min的情况下,观察20例气管切开患者吸痰前、吸痰后2min血氧饱和度的变化。结果：20例气管切开患者不同氧流量吸痰后2min血氧饱和度均高于吸痰前血氧饱和度（P〈0．05）,而不同氧流量吸痰后2min血氧饱和度比较差异均无统计学意义（P〉0．05）。结论：气管切开患者在吸痰前提高氧流量至5L／min,既能有效避免因吸痰引起的低氧血症,又可减少氧疗副作用的发生。     

膨肺湿化吸痰法在心脏外科术后机械通气病人中的应用

[目的]探讨膨肺湿化吸痰法在心脏外科术后机械通气病人中的应用效果。[方法]将72例心脏术后病人随机分为观察组35例,对照组37例。观察组采用膨肺湿化吸痰法,对照组采用常规吸痰法,观察两组病人吸痰前后心率、血氧饱和度的变化及动脉血氧分压、二氧化碳分压的数值,并记录两组的肺不张发生率和机械通气时间。[结果]观察组在吸痰前后心率变化较小,血氧饱和度及动脉血氧分压、二氧化碳分压改善较好,两组病人肺不张发生率、机械通气时间比较差异均有统计学意义(P<0.01)。[结论]膨肺湿化吸痰法是一种安全有效的吸痰方式,能改善病人的低氧状态,并能缩短机械通气时间,降低肺不张发生率。     

不同强度吸痰负压对低体重患儿心脏术后肺部感染吸痰效果的研究

目的:研究不同强度吸痰负压对10 kg以下先天性心脏病术后肺部感染患儿的护理效果。方法:抽取我中心手术治疗后出现肺部感染的10 kg以下婴幼儿,将其随机分为A,B,C组,每组20例,三组患儿给予不同负压吸痰护理,其中A组负压为10 kPa,B组负压为20 kPa,C组负压为30 kPa。比较三组患儿术后气道黏膜损伤情况,吸痰后肺部听诊情况,吸痰后动脉血氧分压及血氧饱和度的变化。结果:与C组比较,B组患儿气道黏膜损伤情况减少(P<0.05),与A组比较,B组患儿吸痰后呼吸音听诊改善明显(P<0.05),与A组和C组比较,B组患儿吸痰后动脉血氧饱和度、动脉血氧分压明显上升(P<0.05)。结论:心脏术后肺部感染的低体重患儿吸痰宜选择20 kPa的压力。     

密闭式吸痰法对使用呼气末正压通气的危重症患者呼吸循环功能的影响

目的 探讨密闭式吸痰法对使用呼气末正压通气(PEEP)的危重症患者动脉血气、呼吸力学和血液动力学的影响.方法 将92例使用PEEP的危重症患者随机分为采用开放式吸痰法(OS)和密闭式吸痰法(CS),通过动脉血气分析、呼吸机参数和PICCO机参数监测2组患者吸痰前1min及吸痰后1min、5min、15min动脉血气、呼吸力学及血液动力学的变化情况.结果 2组患者在吸痰后即刻动脉血氧分压和动脉血氧饱和度均下降,OS组直到吸痰后15min仍低于吸痰前基线水平;而有创收缩压、有创平均动脉压均升高,吸痰后15minOS组仍高于吸痰前基线水平,CS组高于吸痰前基线水平但无差异(p＞0.05);而有创舒张压(DBP)与吸痰前比较2组均无差异(p＞0.05).OS组在吸痰后肺静态顺应性、心脏指数均降低,持续到吸痰后15min仍低于吸痰前基线水平;气道峰压、平台压、平均气道压均升高,持续到吸痰后15min仍显著高于吸痰前基线水平(p＜0.05).CS组在吸痰后持续到吸痰后15min与吸痰前基线水平差异无统计学意义(p＞0.05).结论 密闭式吸痰过程中可以保持持续通气,维持PEEP,避免或减少肺泡萎陷,维持吸痰前后呼吸循环的相对稳定性,是使用正压通气的危重症患者安全有效的吸痰方法.     

不同吸痰方式对肺不张病人动脉血气的影响

[目的]观察不同吸痰方式对肺不张病人动脉血气的影响。[方法]选择24例肺不张并机械通气的危重病人,随机分为两组,密闭式吸痰(CS)组(n=13)和开放式吸痰(OS)组(n=11)。观察两组吸痰前1min及吸痰后3min、20min动脉血pH值、氧分压(PaO2)、二氧化碳分压(PaCO2)、血氧饱和度(SaO2)的变化。[结果]OS组吸痰后3min、20min与吸痰前1min比较,PaO2、SaO2显著下降,差异有统计学意义(P<0.05);CS组吸痰前后上述参数变化比较无统计学意义(P>0.05);与CS组同时段比较,OS组吸痰后PaO2、SaO2显著下降,差异有统计学意义(P<0.05)。[结论]肺不张病人选择CS方式吸痰能较好地维持机体氧合状态。     

心脏术后病人早期行胸部物理治疗的临床观察

为了探讨早期行胸部物理治疗对心脏术后病人血气及心功能的影响，选择４１例病人做自身对照观察。在拔除气管插管后１０ｍｉｎ行雾化吸入，随后叩背、排痰。结果：治疗结束后３０ｍｉｎ与治疗前相比，动脉血氧分压、氧饱和度明显升高，二氧化碳分压明显下降，而心率、血压只在治疗结束时有轻微的改变，治疗后３０ｍｉｎ与治疗前相比无差异。提示心脏术后病人可早期行胸部物理治疗，这对预防肺不张及肺部感染有重要意义     

Liver tissue oxygenation as measured by near-infrared spectroscopy in the critically ill child in correlation with central venous oxygen saturation

OBJECTIVE: To evaluate the clinical usefulness of near-infrared spatially resolved spectroscopic quantitative assessment of liver tissue oxygenation for simple, non-invasive estimation of global tissue oxygenation in critically ill neonates and children. DESIGN: Prospective observational clinical study. SETTING: A tertiary multidisciplinary neonatal and paediatric intensive care unit (23 beds). PATIENTS: One hundred neonates and children consecutively admitted to the paediatric intensive care unit. MEASUREMENTS AND RESULTS: Near-infrared spectroscopic single-point assessment of liver tissue oxygenation index (TOI(Liver)) was compared with global tissue oxygenation as measured by central venous oxygen saturation (SvO(2)) and derived haemodynamic parameters. Data were compared using linear and multiple regression analysis. Overall correlation between TOI(Liver)and SvO(2) was good ( r=0.72, p<0.0001). Multivariable regression revealed that SvO(2) alone explained 51% of the observed variance of TOI(Liver). However, our data demonstrated large inter-individual differences between SvO(2) and TOI(Liver) values. CONCLUSION: Near-infrared spatially resolved spectroscopic quantitative measurement of liver tissue oxygenation correlates well with SvO(2) in critically ill neonates and children. Large inter-individual SvO(2) to TOI(Liver) differences may prevent its use for non-invasive single-point estimation of global tissue oxygenation. Further clinical studies are required to validate the method with other regional and global haemodynamic parameters and to evaluate its clinical use for continuous non-invasive haemodynamic monitoring.     

Preoxygenation in critically ill patients requiring emergency tracheal intubation

OBJECTIVE: To determine the effectiveness of preoxygenation with 100% oxygen in the critically ill patient in preparation for emergency tracheal intubation. DESIGN: Nonrandomized, controlled trial. SETTING: Large, level 1 trauma center, tertiary care intensive care unit. PATIENTS: Critically ill patients failing noninvasive respiratory support techniques who require tracheal intubation followed by mechanical ventilation. INTERVENTIONS: A baseline arterial blood gas was obtained on noninvasive therapy and 4 mins post-100% oxygen therapy with a bag-mask assembly. Best effort to achieve a tight-fitting mask seal was pursued coupled with other mask ventilation maneuvers to optimize noninvasive oxygenation and ventilation. MEASUREMENTS AND MAIN RESULTS: A total of 42 patients consecutively intubated during the 15-month study period were studied. The baseline Pao2 (mean +/- sd) with concurrent noninvasive support was 67 +/- 19.6 mm Hg (range, 43-88 mm Hg) and increased a mean of 37 mm Hg to 103.8 +/- 63.2 mm Hg after 4 mins of preoxygenation with 100% oxygen. A total of 36% of patients had minimal changes (+/-5%) in their baseline Pao2, and only 19% increased their baseline Pao2 by at least 50 mm Hg after preoxygenation maneuvers. CONCLUSIONS: The critically ill patient has little reserve to tolerate interruption of oxygen delivery and, thus, is at risk for hypoxemia during emergency airway management. Preoxygenation efforts as described in this clinical trial appear to be marginally effective in regard to providing a reasonable safeguard against hypoxemia during laryngoscopy and endotracheal intubation.     

Relationship of oxygen delivery and mixed venous oxygenation to lactic acidosis in patients with sepsis and acute myocardial infarction

Critical decreases in oxygen delivery (DO2) and mixed venous oxygen saturation (SvO2) are associated with anaerobic metabolism and, therefore, lactic acidosis. We studied 50 consecutive patients with sepsis and 50 consecutive patients with acute myocardial infarction (AMI) in whom the arterial blood lactate was greater than 1 mmol/L in order to determine critical thresholds of DO2 and SvO2. In both groups, critical values of DO2 or SvO2 associated with lactic acidosis could not be identified. The DO2 ranged from 136 to 811 ml/min.m2 and SvO2 ranged from 28% to 73% in the patients with sepsis. The DO2 ranged from 115 to 434 ml/min.m2 and SvO2 from 17% to 72% in patients with AMI. The absence of threshold values for DO2 and SvO2 probably reflects the influence of distributive flow abnormalities as well as differences in metabolic requirements in these critically ill patients.     

Hemodynamic responses to gram-positive versus gram-negative sepsis in critically ill patients with and without circulatory shock

OBJECTIVE: To examine the hemodynamic patterns of critically ill patients with septicemia to evaluate their relationship to blood bacteriology. DESIGN: Retrospective study. SETTING: Medical ICUs of a tertiary care medical center. PATIENTS: Total of 59 critically ill patients with bacteremia: 33 with Gram-positive and 26 with Gram-negative bacteremia. MEASUREMENTS: Hemodynamic variables and mixed venous oxygen saturation (SvO2) measurements associated with the highest cardiac index measured within 72 hrs of positive blood cultures. MAIN RESULTS: No significant differences in cardiac index, mean arterial pressure, systemic vascular resistance, oxygen extraction ratio, or SvO2 were observed comparing the two groups. CONCLUSION: We were unable to demonstrate clinically important differences between the hemodynamic responses to Gram-positive vs. Gram-negative sepsis.     

Real-time analysis of the change in arterial oxygen tension during endotracheal suction with a fiberoptic bronchoscope

An intra-arterial Clark-type polarographic oxygen electrode was used with a fiberoptic bronchoscope for real-time analysis of the PO2 change during 1 min of suction in patients spontaneously breathing oxygen. There was a strong correlation between values obtained from the intra-arterial electrode (PiO2) and those from blood samples (PaO2), before and at the end of suction; the PiO2/PaO2 ratio was close to one. Continuous PiO2 recordings during suction without supplemental oxygen showed little change in the early period of suction, followed by a steep drop continuing even after suction. This drop in PiO2 was partially attenuated by providing oxygen with high-frequency jet ventilation and was almost completely attenuated by the use of a suction adaptor. Changes in the inspired oxygen concentration indicated the importance of keeping this variable constant during suction to prevent hypoxemia.     

Continuous SvO2 monitoring. A research review.

Nurses have access to continuous SvO2 monitoring as one parameter for evaluating the hemodynamic status in critically ill patients. The research studies on SvO2 monitoring have demonstrated inconsistent results regarding the utility of SvO2 as an assessment tool. Hence, it is necessary to carefully review these research findings for their impact on nursing practice. Nurses must be aware of the possibility of overreliance on continuous SvO2 monitoring and of the limitations of the SvO2 measurement itself.     

Cardiac output from carbon dioxide production and arterial and venous oximetry

OBJECTIVE: To determine cardiac output from measurements of CO2 production (VCO2), and arterial (SaO2) and mixed venous (SvO2) oxygen saturations, using a modified Fick equation, in which cardiac output = VCO2/[k (SaO2 - SvO2)], where k represents a constant. DESIGN: A metabolic measurement cart was used to measure VCO2 and oxygen consumption (VO2) at 3-min intervals. SaO2 and SvO2 were measured via a pulse oximeter and a fiberoptic right heart catheter, respectively. The initial value of k for each study was determined from initial simultaneous measurements of thermodilution cardiac output, VCO2, SaO2, and SvO2 via the equation k = VCO2/[cardiac output (SaO2 - SvO2)]. The value of k was assumed to remain constant for the entire study period. Thereafter, cardiac outputs calculated from k and the measurements of VCO2, SaO2, and SvO2 were compared with the simultaneously obtained cardiac outputs determined by thermodilution. Similarly, cardiac outputs calculated from the traditional oxygen Fick equation, where cardiac output = VO2/[13.4 x hemoglobin (SaO2 - SvO2)], were compared with the simultaneously acquired cardiac outputs determined by thermodilution. SETTING: Surgical ICU in a Veterans Affairs Medical Center. PATIENTS: Seven postoperative patients, mechanically ventilated using the intermittent mandatory ventilation mode, were studied over a mean period of 4 hrs. RESULTS: Cardiac output (obtained from VCO2 and oximetry saturations) was closely related to thermodilution cardiac output: with linear regression showing r2 = .96 and standard error of the estimate = 0.59 L/min, n = 21; and, with bias and precision = 0.17 and 0.68 L/min, respectively. The traditional oxygen Fick cardiac output was also closely related to the thermodilution cardiac output (r2 = .81, standard error of the estimate = 1.46 L/min, n = 22; bias and precision = 0.31 and 1.46 L/min, respectively). CONCLUSION: The proposed method for calculating cardiac outputs solely from VCO2 and oximetry saturations yields results that correspond closely to thermodilution determined cardiac outputs. The method is simple and avoids the difficulties in the Fick method associated with accurate VO2 measurement. This approach may be suitable for continuous cardiac output monitoring in critically ill patients.     

Conjunctival oxygen tension monitoring in emergency department patients

Conjunctival oxygen tension (PcjO2) was sequentially monitored in 96 medical and surgical patients admitted to the emergency department resuscitation suite during a 6-month period. There were 28 patients with cardiac arrest, 44 with major trauma, and 24 with severe medical problems. A total of 2,392 PcjO2 data points were collected in these patients. In patients with cardiac arrest, PcjO2 showed changes in physiological condition as early as or earlier than measurement of vital signs. Measurement of PcjO2 and the finding of a PcjO2 index (PcjO2/PaO2) less than .5 in normotensive multiple trauma patients allowed rapid detection of hemorrhagic hypovolemia. In critically ill medical patients, low values for PcjO2 were found with hypoxemia as well as in conditions associated with decreased cardiac output and tissue oxygen delivery. These two conditions could be distinguished by measuring PaO2 and calculating the PcjO2 index; a PcjO2 index less than .5 was associated with diminished peripheral perfusion and cardiac output, and a PcjO2 index greater than .5 indicated hypoxemia without any compromise in cardiac output. In the group of critically ill surgical and medical patients included in this study, conjunctival oxygen monitoring provided clinically useful information not available from vital signs and permitted identification of physiological instability associated with abnormalities in peripheral tissue perfusion and oxygenation as early as or earlier than conventional monitoring methods.