摘要:

Because acute blood loss may produce abnormal tissue perfusion and oxygenation before affecting blood pressure, we measured conjunctival (PcjO2) and arterial (PaO2) oxygen tensions and blood volume in 16 normotensive emergency department patients whose histories were consistent with significant blood loss. All eight patients with measured blood volume less than 85% of normal, as well as two euvolemic patients, had a PcjO2/Pao2value of 0.57 or less, yielding a sensitivity of 100%, specificity of 75%, and positive predictive value of 80%. Lowering the cutoff point to 0.50 increased specificity and positive predictive value to 100% while reducing sensitivity to 88%. These results demonstrate that the Pcjo2/Pao2ratio is an early, sensitive, and specific indicator of significant blood volume deficit.

ISSN:0090-3493    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

We found that results from a transcutaneous arterial hemoglobin oxygen-saturation monitor correlated well with those from a co-oximeter. The monitor was not disturbed by differing hematocrit levels, the presence of fetal hemoglobin, or hypotension.We also found that the results of simultaneous transcutaneous arterial hemoglobin oxygen saturation (StcaO2) and transcutaneous oxygen tension (PtcO2) monitoring were predictably correlated over a wide range of hemoglobin saturations in preterm infants. When Stcao2was between 80% and 95%, Ptco2was at a safe level of 40 to 80 torr in 94% of the patients studied. Stcao2monitoring as an index of arterial oxygenation has several advantages for the preterm infant.

ISSN:0090-3493    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Catheter-tip sensors used to measure arterial and tissue Pco2produced a baseline drift less than 2 torr during 1 to 5 h of monitoring. Clot formation during Paco2monitoring was avoided by continuous infusion of a small amount of heparin solution around the sensor. PaCO2sometimes fluctuated periodically during spontaneous breathing but not during mechanical ventilation. Subcutaneous tissue PCO2, monitored by placing the sensor under the skin on the chest, showed an almost parallel movement to PaCO2with a time delay of a few minutes. This PCO2sensor was durable and accurate for up to 5 h of continuous clinical monitoring.

ISSN:0090-3493    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

A device to measure surface oxygen tension of the palpebral conjunctiva (PcjO2) was developed and tested in 12 mongrel dogs subjected to normoxia, hyperoxia, and hypoxia. Intravascular pressure, hemodynamic, and bulk oxygen transport variables were measured simultaneously with PcjO2and transcutaneous O2(PtcO2) and CO2(PtcCO2). PcjO2closely paralleled Pao2as the fractional inspired O2concentration was changed from 0.21 up to 1.0 and down to 0.05; the correlation coefficient, r, was 0.95 for 305 data sets. During hyperoxia there were no significant hemodynamic or bulk O2transport changes, but during hypoxia, the cardiac output and O2extraction increased while Pao2, PtcO2and PcjO2fell; O2delivery and O2consumption were maintained until just before death.

ISSN:0090-3493    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

To evaluate possible physiologic mechanisms in hemorrhagic shock, sequential hemodynamics, O2transport, conjunctival O2(PcjO2), transcutaneous blood gases (PtcO2, PtcCO2), and core and conjunctival temperature (Tcore, Tcj) were measured during a control period, after hemorrhage, after reinfusion of the shed blood, and subsequently during terminal normovolemic shock in eight anesthetized dogs. The PtcO2sensor requires surface heating to 44° or 45°C, whereas the PcjO2sensor measures surface temperature but does not heat the tissue, thus avoiding heat-induced artifacts. Shortly after onset of hemorrhage, hemodynamic variables, bulk O2transport, and tissue O2tensions decreased abruptly. Prolongation of hemorrhage further deteriorated these variables. Reinfusion of the shed blood returned all values except PcjO2to the normal range. In the terminal stage, all variables except PaO2again deteriorated; decreased O2transport impaired oxygen consumption, which in turn reduced both central and peripheral heat production. Lowered oxygen consumption, Tcore and Tcj reflect decreases in total-body and local tissue metabolism. These data are consistent with the concept that tissue O2tension represents the balance between O2supply and O2demand and thus reflects overall O2metabolism, which may be ratelimited by circulatory deficiencies.

ISSN:0090-3493    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The fractional elimination rate of exogenous fat, and fat-mobilizing lipolysis in relation to plasma catecholamine (CA) levels were studied in seven ventilatortreated ICU patients. Blood levels of CA, triglycerides, cholesterol and free fatty acids (FFA) were also analyzed before and during constant infusion of a soybean oil emulsion (Intralipid). Triglyceride concentrations rose significantly during the infusion. FFA levels also increased significantly within 30 min after the infusion was begun, reflecting fatty acids derived from Intralipid triglycerides. Plasma norepinephrine levels showed large interindividual variations and were inversely related to FFA concentrations. No correlation was found between plasma CA levels and the fractional removal rate of fat. These data suggest a deficiency of substrate in these critically ill patients.

ISSN:0090-3493    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Plasma lipid peroxide measured as thiobarbituric acid reactive substances (TBARS) and alpha-tocopherol levels in 24 critically ill patients were compared with those of control subjects. The mean plasma alphatocopherol level was significantly lower and the mean TBARS level was significantly higher in critically ill patients. Eight ICU patients developed disseminated intravascular coagulation (DIC); the mean TBARS level during DIC was significantly above the mean pre-DIC level. These results indicate that lipid peroxidation may contribute to the development of DIC in critically ill patients.

ISSN:0090-3493    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Because lateral position can be used to locate a pulmonary artery catheter tip in lung regions where venous pressure exceeds alveolar pressure, we studied the effect of lateral position on the correlation between pulmonary artery occlusion pressure (Pw) and left atrial pressure (Pla) at various increments of positive-end expiratory pressure (PEEP). In ten normal anesthetized pigs, catheters were placed in the left atrium and right and left pulmonary arteries; simultaneous measurements of Pla and Pw from both catheters were obtained in the supine, right lateral, and left lateral positions. Pw obtained in the lateral position when the catheter tip was vertically located below the left atrium (“lower”) more accurately reflected Pla changes than Pw obtained from catheters above the left atrium, at PEEP levels less than 20 cm H2O. Although most catheter tips were located below the left atrium in the supine position, our data from the lower catheter more accurately assessed Pla than did the Pw obtained in the supine position; this was particularly evident when the catheter tip was located vertically above the left atrium. These findings suggest that the lateral position can be useful in measuring Pw during continuous positive-pressure ventilation. However, further studies in humans are needed before this maneuver can be recommended.

ISSN:0090-3493    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

We compared cuff to simultaneous direct intra-arterial pressure in 26 seriously ill patients, in order to: (a) test the accuracy of oscillometric and auscultatory estimates of direct systolic pressure; (b) test muffling and disappearance of sound as indices of direct diastolic pressure; (c) gain insight into the timing of the different phases of Korotkoff sounds; and (d) assess the local and general effects of cuff inflation on blood pressure. We found that conventional estimation of systolic blood pressure by auscultation of the first Korotkoff sound (K1) underestimates direct systolic pressure by an average of 16 to 17 mm Hg. Oscillometric pressure measurement provides a significantly better estimate than Kl but still underestimates by 7 to 8 mm Hg. These systolic cuff measurements are biased downward from direct values because of local cuff effect and cuff error. Diastolic cuff measurements deviate from direct values primarily because of a local cuff effect which produces an upward bias of 5 mm Hg at the point of sound muffling (K4), and 3 mm Hg at the point where sounds disappear (K5). We recommend oscillometric measurement of systolic pressure and K5 measurement of diastolic pressure as the best indirect estimates of blood pressure in critically ill patients.

ISSN:0090-3493    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Of 38 patients undergoing median sternotomy for cardiac operations all developed profound restrictive defects in pulmonary function during the first 72 h after tracheal extubation. Although decreased lung volumes were refractory to correction by vigorous, aggressive pulmonary therapy during this period, frequent and supervised treatment may prevent further deterioration in pulmonary function. The overall incidence of pneumonia was only 3% (1/38). Continuous positive airway pressure delivered by mask proved to be a nearly effortless form of postoperative respiratory therapy that was less painful than incentive spirometry or coughing and deep breathing, and therefore may be preferable.

ISSN:0090-3493    

出版商:OVID    

年代:1984

数据来源: OVID