Effect of Ketamine on Heterogeneity of Cerebral Microregional Venous O2 Saturation in the Rat

A study has been undertaken to determine whether local changes in PO2 could be a factor in the regulation of retinal blood flow during 100% O2 breathing. For this purpose we have measured simultaneously in eyes of anesthetized and artificially ventilated miniature pigs the change in local preretinal PO2 and retinal blood flow using O2-sensitive microelectrodes and laser Doppler velocimetry. Although preretinal intervascular PO2 changed little, periarteriolar PO2 increased markedly during 100% O2 breathing. When measured less than 50 microns from the arteriolar wall, the time course of this increase preceded that of the decrease in retinal blood flow. The results indicate that O2 diffusing through the wall of the large retinal arterioles represents the most important component of periarteriolar PO2. This diffusion coupled with the decrease in retinal blood flow could play a major role in the regulation of inner retinal PO2. The data also suggest that diffusional shunting of O2 between retinal arterioles and veins could explain the unexpected increase in venous O2 saturation during 100% O2 breathing that has been previously reported by others. The finding that retinal periarteriolar PO2 is always higher than the PO2 in the outer retina does not support the previously formulated hypothesis that O2 from the choroid is responsible for the constriction of the arterioles during hyperoxia.

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Myocardial Venous O2 Saturation Becomes More Heterogeneous during Hypoxic and Carbon Monoxide Hypoxia

Microvascular Research ◽

10.1006/mvre.1995.1022 ◽

1995 ◽

Vol 49 (3) ◽

pp. 253-267 ◽

Cited By ~ 2

Author(s):

Naihong Zhu ◽

Harvey R. Weiss

Keyword(s):

Carbon Monoxide ◽

Venous O2 Saturation

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Effect of T4-induced cardiac hypertrophy on O2 supply-consumption balance during normoxia and hypoxia

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1984.246.3.h374 ◽

1984 ◽

Vol 246 (3) ◽

pp. H374-H379

Author(s):

K. Talafih ◽

G. J. Grover ◽

H. R. Weiss

Keyword(s):

Blood Flow ◽

Myocardial Blood Flow ◽

Left Ventricular ◽

Saline Control ◽

O2 Consumption ◽

Blood Flows ◽

O2 Extraction ◽

New Zealand White Rabbits ◽

O2 Supply ◽

Venous O2 Saturation

The purpose of this study was to determine if thyroxine-induced hypertrophic hearts can maintain an adequate O2 supply-consumption balance both at rest and under hypoxic stress. New Zealand White rabbits were given 0.5 mg/kg L-thyroxine (T4) for 3 or 16 days, and a third group served as a control. Chests were opened under anesthesia, and myocardial blood flow was determined using microspheres. In half of these animals, microspectrophotometric determinations were made on left ventricular arterial and venous O2 saturation, and by combining this data with blood flows, O2 consumption was determined. The other animals were then subjected to hypoxia (8% O2 in N2), and flows and O2 consumption were again determined. T4 increased arterial pressure and heart rate in normoxic animals and also increased myocardial blood flow 65 and 210% for 3- and 16-day T4 groups, respectively, with no regional differences. O2 extraction was also increased in T4 animals. O2 consumption increased 134 and 280% in 3- and 16-day T4 groups. Only normoxic saline controls had a regional O2 consumption difference with subendocardial O2 consumption higher than subepicardial values. When compared with their respective normoxic groups, blood flow increased 49 and 101% for the hypoxic 3- and 16-day T4 groups. Hypoxia had no effect on saline control blood flow. Hypoxia decreased O2 extraction 29 and 41%, respectively, in the 3- and 16-day T4 groups and was unchanged in saline controls.(ABSTRACT TRUNCATED AT 250 WORDS)

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Effect of pentobarbital on cerebral regional venous O2 saturation heterogeneity

Brain Research ◽

10.1016/0006-8993(92)90989-m ◽

1992 ◽

Vol 591 (1) ◽

pp. 146-150 ◽

Cited By ~ 17

Author(s):

Arabinda K. Sinha ◽

Oak Z. Chi ◽

Harvey R. Weiss

Keyword(s):

Venous O2 Saturation

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Effect of Ketamine on Heterogeneity of Cerebral Microregional Venous O2 Saturation in the Rat

Anesthesia & Analgesia ◽

10.1213/00000539-199411000-00008 ◽

1994 ◽

Vol 79 (5) ◽

pp. 860???866 ◽

Cited By ~ 13

Author(s):

Oak Z. Chi ◽

Hwu M. Wei ◽

Sanford L. Klein ◽

Harvey R. Weiss

Keyword(s):

Venous O2 Saturation

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The Central Venous O2 Saturation Test in Acute Pulmonary Fat Embolism

Angiology ◽

10.1177/000331977702800107 ◽

1977 ◽

Vol 28 (1) ◽

pp. 40-47

Author(s):

E.M. Cordasco ◽

Oscar Piedad ◽

J. Chaitoff

Keyword(s):

Fat Embolism ◽

Central Venous ◽

Pulmonary Fat Embolism ◽

Venous O2 Saturation

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Central venous O2 saturation and rate of arterial desaturation during obstructive apnea

Journal of Applied Physiology ◽

10.1152/jappl.1989.66.3.1477 ◽

1989 ◽

Vol 66 (3) ◽

pp. 1477-1485 ◽

Cited By ~ 18

Author(s):

E. C. Fletcher ◽

R. Kass ◽

J. I. Thornby ◽

J. Rosborough ◽

T. Miller

Keyword(s):

Cardiac Output ◽

Continuous Monitoring ◽

Base Line ◽

Central Venous ◽

Cuffed Endotracheal Tube ◽

The Mean ◽

Arterial O2 Saturation ◽

Spontaneously Breathing ◽

Venous O2 Saturation ◽

Mixed Venous

We examined the rate of fall of arterial O2 saturation (dSao2/dt) after apnea onset in four spontaneously breathing adult male baboons. We postulated that a lower mixed venous O2 saturation (Svo2) would steepen dSao2/dt by more rapid depletion of alveolar O2. Single isolated (NREP) and five or more sequential repetitive apneas (REP) were created by clamping an indwelling cuffed endotracheal tube at end expiration. Fiberoptic catheters were used for continuous monitoring of Sao2, Svo2, and cardiac output. The mean dSao2/dt for all duration NREP apneas was 0.60%/s. Mean dSao2/dt increased above base line for each consecutive REP apnea and was higher in 60 s than in 45 and 30 s REP apnea series. The increase in dSao2/dt corresponded closely with the fall in preapneic Svo2. Preapneic arterial O2 content fell during successive REP apneas but the maximal decrement from base line (1.3 ml/dl) was much less than the maximal decrement in preapneic mixed venous O2 content of 5.1 ml/dl. Preapneic cardiac output for NREP apneas and nadir cardiac output for REP apneas remained constant. Nadir cardiac output for NREP apneas showed higher values for longer duration apneas. We concluded that dSao2/dt is inversely related to preapneic Svo2.

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