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Biomedical subjects

K K Tremper

Publications and source records attributed to K K Tremper.

At least 73 records · Page 4Linked to original sources
PubMed1986

Continuous noninvasive estimation of cardiac output by electrical bioimpedance: an experimental study in dogs.

A new device has been developed to estimate continuously and noninvasively cardiac output from the thoracic electrical bioimpedance (CObi). CObi was compared to cardiac output by thermodilution (COtd) in five anesthetized dogs. Blood pressure, blood volume, and blood flow were manipulated by hemorrhage and infusions of sodium nitroprusside and phenylephrine. These data were used to determine the correlation between CObi and COtd under conditions of hypotensive normal flow and normotensive low flow, as well as during hemorrhagic shock and resuscitation. The CObi device was calibrated in vivo to COtd for each dog at the beginning of each experiment. CObi had a significant positive correlation with COtd throughout the experiments (r = 0.84, slope = 0.91, intercept = 0.55, p less than 0.01), and CObi predicted COtd with a standard error of the estimate of 0.81 L/min. Neither heart rate nor mean arterial pressure was significantly correlated with COtd or CObi. During severe hemorrhagic shock, CObi could not determine cardiac output in two of the dogs when COtd averaged 1.7 L/min. These data indicate that CObi is a blood-flow related variable that can be monitored continuously.

Animals↗
PubMed1985

Transcutaneous PO2 monitoring during a Himalayan ascent.

Transcutaneous PO2 (PtcO2) measurements were taken daily on seven subjects during two nine day ascents of the Himalayas to an altitude of 4,579 meters. Five of the subjects lived in areas under 450 meters (Group I), while two subjects lived at an altitude of 3,100 meters (Group II). The PtcO2 values decreased with increasing altitude. The Group II subjects had PtcO2 values greater than the Group I subjects and the difference became greater with increasing altitude. The linear regression lines of PtcO2/pbO2 to Group I during ascent and decent were lower than the regression line for Group II (PbO2 is the barometric oxygen partial pressure). The regression line for Group I data during the second half of the trek approached the data for Group II. We conclude that acclimatization to high altitude is possibly associated with increasing peripheral tissue oxygenation as assessed by PtcO2 values.

Acclimatization↗
PubMed1985

Transcutaneous PO2 monitoring during sodium nitroprusside infusion.

To determine the effect of vasodilator-induced hypotension on the relationship between transcutaneous PO2 (PtcO2) and PaO2, six mongrel dogs and 20 patients were monitored before and during infusion of sodium nitroprusside (SNP), with PtcO2 sensors heated to 45 degrees C. First, SNP infusion was used to lower the mean arterial pressure (MAP) of anesthetized dogs, in steps of approximately 25%, to 49 +/- 3 (SD) mm Hg. There were no significant changes in cardiac output, oxygen consumption, PtcO2, PaO2, or PtcO2 index (PtcO2/PaO2). Twenty patients were monitored during general anesthesia. Fifteen patients were being treated for acute hypertension with SNP, and in five patients hypotension was induced with SNP to minimize blood loss. There was a significant decrease in MAP, PaO2, and PtcO2, and a significant increase in alveolar-arterial PO2 difference during SNP infusion. PtcO2 index did not change significantly from its preinfusion value in either group.

Adult↗
PubMed1985

Laser Doppler velocimetry as a monitor of cardiac output changes in dogs.

Cutaneous blood flow may be measured utilizing a continuous, noninvasive technique, laser Doppler velocimetry (LDV). Monitoring of cutaneous blood flow by LDV might be a useful method to monitor cardiac output. To test this hypothesis, sequential measurements of cardiac output, LDV, and transcutaneous oxygen (PtcO2) were made on 10 anesthetized dogs during experimental shock. There was significant correlation between LDV and cardiac output, while PtcO2 reflected cardiac output only at low flow states. These results show that, in the animal model, cutaneous LDV is a sensitive and specific method for monitoring cardiac output changes.

Animals↗
PubMed1985

Continuous transcutaneous PCO2 monitoring during epidural morphine analgesia.

We evaluated the transcutaneous PCO2 (PtcCO2) sensor as a ventilation monitor for patients receiving epidural morphine analgesia during interstitial radiation therapy for carcinoma of the cervix. The sensor was heated to 42 degrees C. Ten patients were monitored for 18 +/- 7 h after 2.9 +/- 0.5 mg of morphine was injected epidurally. Baseline respiratory rate (RR) and PtcCO2 were 21 +/- 3 breath/min and 37 +/- 8 torr, respectively. Peak PtcCO2 was 43 +/- 7 torr, corresponding to a RR of 19 +/- 3 breath/min. The increase of PtcCO2 from baseline was statistically significant. PtcCO2 peaked from 1 to 19 h after epidural morphine, and 90% of patients showed peak values between 11 PM and 4:30 AM. The prolonged monitoring caused no complications. Although there was no clinically significant respiratory depression in these patients, the PtcCO2 sensor may be a useful monitor of ventilation during epidural morphine administration.

Aged↗
PubMed1985

Perfluorochemical emulsion oxygen transport fluids: a clinical review.

Perfluorochemical liquids are inert, immiscible in water, and have approximately 20 times the solubility for oxygen and carbon dioxide as does water. When emulsified in a normal saline solution, they can act as an oxygen-transporting resuscitation fluid. Fluosol-DA 20% is the first perfluorochemical emulsion to be studied clinically. It can supplement oxygen transport in anemic patients, but no control study has as yet determined its clinical effectiveness.

Anemia↗
PubMed1985

Blood and plasma substitutes--plasma expansion and oxygen transport properties.

Because of the risks and costs of blood and blood product infusion, developing blood and plasma substitutes is of significance. Two currently utilized substances, dextran and hydroxyethyl starch, are effective colloid plasma expanders. The dextrans have properties that improve microcirculatory blood flow but are associated with several possible adverse effects. Hydroxyethyl starch is a well-tolerated agent that has efficacy similar to albumin but at a lower cost. Two newer substances, perfluorocarbons and stroma-free hemoglobin, are being developed to improve oxygen transport as well as plasma expansion.

Blood Substitutes↗
PubMed1984

Perfluorocarbon infusion in bleeding patients refusing blood transfusions.

Six severely anemic surgical patients who refused blood products were treated with a perfluorochemical (PFC) emulsion (Fluosol-DA 20%). When these patients received high inspired oxygen concentrations, the emulsion resulted in moderate increases of arterial oxygen content but considerable increases of oxygen consumption, suggesting improved microcirculatory oxygen distribution. The mean +/- SD percentages of consumed oxygen transported by dissolved oxygen in PFC and PFC plus plasma emulsions were 22% +/- 5% and 60% +/- 12%, respectively. Several adverse clinical effects were seen, however, including transient decreases in leukocyte counts, hypotension, and abnormal hepatic and pulmonary function.

Anemia↗
PubMed1984

Transcutaneous PO2 measurement.

Transcutaneous PO2 sensors have been developed over the past ten years from the same basic electrodes used in conventional blood gas machines. The skin is heated to enable the skin surface sensors to respond quickly to the gas tensions beneath them. PtcO2 is a variable which reflects the PO2 in the peripheral tissue. PtcO2 has its own range of normal values and it responds to cardiopulmonary changes which affect tissue oxygenation. In the majority of patients, those without decreased cardiac output, PtcO2 follows the trend of the arterial gas tension, and the PtcO2 value decreases relative to PaO2 with increasing patient age (Table II). When there is severely reduced cardiac output and peripheral perfusion, the PtcO2 values will deviate from their relationship with the arterial tensions and become blood flow dependent, thus providing quantitative information regarding blood flow. It is likely that the technique of transcutaneous PO2 monitoring will gain wider acceptance because it is a noninvasive and continuous monitor which provides useful information regarding tissue oxygenation.

Adult↗