Two levels of the inspired oxygen fraction in propofol-anesthetized dogs with high intracranial pressure: cardiopulmonary function

Abstract

In the initial stage of traumatic brain injury, the use of 1.0 inspired oxygen fraction (FiO 2 ) is indicated. However, high FiO 2 has been correlated with atelectasis. Thus, the effects of FiO 2 = 1.0 and FiO 2 = 0.6 on the cardiopulmonary function in propofol-anesthetized dogs with high intracranial pressure (ICP) were evaluated. Eight dogs were anesthetized on two occasions, receiving, during controlled ventilation, an FiO 2 = 1 (G100) or an FiO 2 = 0.6 (G60). Propofol was used for induction (10mg.kg -1 ) followed by a continuous rate infusion (0.6mg.kg -1 .minute -1 ). An increase in the ICP was induced by temporary obliteration of the right jugular vein (OJ v ) 50 minutes after induction of anesthesia. The measurement was taken twenty minutes after OJ v (T0) and then at 15-minute intervals (T15 to T60). Alveolar oxygen partial pressure in G60 was lower than in G100 during the whole procedure. Alveolar-arterial oxygen gradient in G100 was greater than in G60 at T0 and at T60. No differences were observed for arterial oxygen partial pressure/inspired oxygen fraction ratio, arterial-to-alveolar oxygen pressure ratio, respiratory index, venous admixture, oxygen delivery, oxygen consumption, oxygen extraction, heart rate, mean pulmonary arterial pressure, pulmonary arterial occlusion pressure, cardiac index, stroke index and systemic vascular resistance index. In G100, mean arterial pressure at T0 was higher than at T45. In dogs with high ICP, the cardiopulmonary function was not influenced by the different FiO 2 used.Keywords: dog, total intravenous anesthesia, cerebral autoregulation, hemodynamic, venous admixture RESUMO No estágio inicial do trauma encefálico, o emprego de fração inspirada de oxigênio (FiO

Intracranial pressure monitoring in normal dogs using subdural and intraparenchymal miniature strain‐gauge transducers

“…Nonfluid coupled ICP transducers using either catheter tip miniature strain gauges or fiber‐optic‐linked catheter tip diaphragm technology have distinct advantages over external transducers because these devices do not require “leveling” with the head, although they cannot be recalibrated to zero once they are inserted. Intracranial fiber‐optic or solid state capacitance systems have been shown to provide accurate determination of ICP in both cats and dogs, but substantial limitations of this system include the necessity of anchoring the device to the skull by means of a subarachnoid bolt and the inherent fragility of the fiber optics.…”