Biomedical subjects

T L Baker

Publications and source records attributed to T L Baker.

4 recordsLinked to original sources

PubMed1979

Sleep-waking patterns in hypoxic kittens.

Kittens at 10, 20, and 40 days of age were made intermittently hypoxic in 10 or 7% oxygen chambers for either 3 or 8 days. Respiration, EKG, EEG, and neck and eye movements were recorded during hypoxia. Compared to 21% oxygen controls, hypoxic kittens had fewer and shorter epochs of active sleep, and longer epochs of quiet sleep. Some hypoxic kittens exhibited slow and labored respiration during quiet sleep and transitional epochs, which reversed during active sleep. Kittens that showed most pronounced respiratory changes or died had less active sleep than kittens that compensated adequately and survived. These results suggest that active sleep may be important for stimulation of respiration during infancy. Suppression of active sleep, augmentation of quiet sleep, or other disturbances to normal sleep-waking patterns during hypoxia, may increase the risk for hypoxic respiratory depression and death.

Animals↗

PubMed1979

Sleep apnea in hypoxic and normal kittens.

Frequency and characteristics of apneas were studied in 10-, 20-, and 40-day old kittens during several days of exposure to 21%, 10%, or 7% oxygen atmospheres. Ninety-seven percent of all apneas occurred during sleep or at transitions between sleep and waking states. Hypoxic kittens, compared to controls, had greatly decreased apnea frequency, but other characteristics of apneas did not differ significantly. Apneas in both control and hypoxic kittens were normal, stereotyped events and were not considered to represent pathological processes. Evaluation of events preceding apneas indicated that a majority of apneas followed augmented breaths and/or brief arousals. We suggest that apnea, heart rate changes during apnea, and frequently concurrent transitions in sleep-waking state may be causally related to these pre-apnea events. The results of this study and a parallel study of human infants suggest that below-normal apnea frequency may indicate hypoxemia and may be associated with higher risk for Sudden Infant Death Syndrome.

Age Factors↗

PubMed1979

Sleep apnea in normal kittens.

Apneic episodes in normal 10-, 20-, and 40-day-old kittens were assessed with polygraphic recordings. End expiratory apneas, usually preceded by somatic activity and/or augmented breaths, with durations less than 10 sec were observed in quiet sleep, active sleep, and transitions between states in all age groups. The highest apnea density was found at state transitions. Heart rate decelerations occurred before, during, and following apneas, but decelerations were not related to apnea duration. Combined central and obstructive components were associated with 9% of apneas in normal kittens.

Age Factors↗

PubMed1977

Reversal of cardiopulmonary failure during active sleep in hypoxic kittens: implications for sudden infant death.

Experimentally induced hypoxia in kittens precipitated episodes of depressed respiration and irregular cardiac function during quiet sleep, waking, and transitional states. The onset of active sleep stimulated both breathing and heart rate and decreased abnormal variability in these functions. However, hypoxia markedly reduced the proportion of active sleep. These data suggest that active sleep protects against respiratory and cardiac abnormalities in infants. Chronic hypoxemia or other factors that reduce active sleep in infants, including the normal developmental decrement in this state, may increase the risk of cardiopulmonary failure and death.

Age Factors↗