Effect of venous oxygenation on arterial desaturation rate during repetitive apneas in lambs
| Autor: | Malcolm Howard Wilkinson, Philip J. Berger, Vojta Brodecky, N. Blanch |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Pulmonary and Respiratory Medicine
Lung Sheep Physiology business.industry Apnea chemistry.chemical_element Venous blood Oxygenation Oxygen Models Biological medicine.anatomical_structure Sleep Apnea Syndromes chemistry Animals Newborn Anesthesia Respiration medicine Arterial blood Animals Lung volumes medicine.symptom business Hypoxia |
| Zdroj: | Respiration physiology. 101(3) |
| ISSN: | 0034-5687 |
| Popis: | While arterial oxygen desaturation during apnea is a common occurrence in adults and infants, the factors determining the rate of desaturation are poorly understood. We describe a theoretical model which suggests that arterial desaturation during an apneic episode occurs in two stages. In the initial stage (stage 1) the oxygen store in the lung is depleted, while in the second phase of the desaturation process (stage 2) tissue oxygen needs are met predominantly by depletion of the blood store. Our model predicts that preapneic venous oxygenation (Sv O 2 ) will strongly influence the rate of desaturation in stage 1 but not in stage 2. We therefore examined the effect of changing preapneic Sv O 2 on the rate of arterial oxygen desaturation (Ṡa O 2 ) during stage 1 and stage 2 apnea in anaesthetised 10–20 day-old lambs. Preapneic arterial oxygen saturation was maintained constant. In agreement with the model's prediction there were two stages to the desaturation process and during stage 1 a significant increase in Ṡa O 2 was observed when preapneic Sv O 2 was lowered; Ṡa O 2 was −3.1 ± 0.4%.sec −1 when Sv O 2 = 47.4 ± 2.1% increasing to −5.8 ± 0.7%.sec −1 when Sv O 2 = 28.3 ± 1.2%. During stage 2, Ṡa O 2 was −1.62 ± 0.07%.sec −1 and was independent of preapneic Sv O 2 , also in accord with the model's prediction. In order to assess whether the accelerated desaturation rate we observed in stage 1 could have resulted from a decline in lung volume during apnea, rather than lower levels of Sv O 2 , we repeated the experiment with CPAP applied. Under these conditions Ṡa O 2 continued to be greater at lower preapneic Sv O 2 levels. In summary, lowered preapneic Sv O 2 has a potent influence on Ṡa O 2 during stage 1 of the desaturation process but not during stage 2. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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