Hemodinâmica de diferentes frações inspiradas de oxigênio em cães submetidos à infusão contínua de propofol sob ventilação espontânea

Intracranial variables in propofol or ABSTRACTThe effects of subarachnoid administration of iohexol on intracranial hemodynamic in dogs anesthetized with propofol or sevoflurane were evaluated. Thirty adult animals (10.92.9kg) were distributed into two groups: PG, where propofol was used for induction (100.5mg/kg), followed by a continuous rate infusion at 0.550.15mg/kg/hour, and SG, where sevoflurane was administered for induction (2.5 MAC) and for anesthetic maintenance (1.5 MAC). A fiberoptic catheter was implanted on the right superficial cerebral cortex to monitor intracranial pressure (ICP). After 30 minutes, cerebrospinal fluid (CSF) was collected at the cisterna magna and iohexol was injected. The measurements were performed before CSF collection (TA), after the iohexol injection (T0), and at 10-minute intervals (T10 to T60). Intracranial pressure decreased at T0 in SG. Cerebral perfusion pressure at T0 was higher than at TA, T50 and T60 in PG, but in SG, the mean value at T0 was higher than the ones from T20 to T60. Mean arterial pressure at T0 was higher than at TA in PG, while in SG, the values from T20 to T60 were lower than at T0. The heart rate at T60 was lower than at T0 in PG. Cardiac output at TA was lower than at T60 in SG. The cerebrospinal fluid collection and administration of iohexol promoted decrease in intracranial pressure in sevolflurane-anesthetized dogs and increase in cerebral perfusion pressure in propofol-anesthetized dogs.Keywords: anesthesia, dogs, cerebral autoregulation, myelography Palavras-chave: cão, anestesia, autoregulação cerebral, mielografia RESUMO Avaliaram-se os efeitos da administração subaracnóidea de iohexol sobre a hemodinâmica intracraniana em cães anestesiados com propofol ou sevofluorano. Trinta e dois animais (10,9±2,9kg) foram distribuídos em dois grupos: no GP, o propofol foi usado para indução, 100.5mg/kg, seguido por infusão contínua, 0,55±0,15mg/kg/min; no GS, o sevofluorano foi administrado para indução, 2,5 CAM, e manutenção, 1,5 CAM, da anestesia. O cateter de fibra óptica foi implantado na superfície direita do córtex cerebral para monitorar a pressão intracraniana (PIC). Após 30 minutos, o fluido cerebroespinhal (FCS) foi coletado da cisterna magna e o iohexol injetado. As mensurações ocorreram antes da coleta do FCS (TA), depois da injeção de iohexol (T0) e em intervalos de 10 minutos (T10 a T60

Section: Discussionsupporting

confidence: 85%

“…In PG, the stability of HR and CO corroborates data registered by Nunes et al (2008). According to Ferro et al (2005), in dogs breathing spontaneously, the continuous rate infusion of propofol (0.2; 0.4 and 0.8mg kg -1 minute -1 ) did not promote changes in heart rate.…”

Section: Discussionsupporting

confidence: 77%

Intracranial variables in propofol or sevoflurane-anesthestized dogs subjected to subarachnoid administration of iohexol

Nunes

Leite²,

Paula³

et al. 2011

“…Regarding HR, the values remained stable in all groups (Table 1), corroborating Nunes et al (2008), who did not observe significant changes in HR and MAP in propofol-anesthetized dogs during spontaneous ventilation with FiO 2 = 1.0 or FiO 2 = 0.6. Besides, MAP was higher than 80mm Hg ( Table 1), suggesting that perfusion was not impaired, because MAP > 65mm Hg is considered sufficient for perfusion maintenance of all vital organs and tissues (Miller, 1986).…”

Section: Discussionsupporting

confidence: 82%

“…Besides, for the initial stage of traumatic brain injury, 100% oxygen has been indicated (Falcão et al, 2006). In this study, FiO 2 of 1.0 was chosen because the 100% oxygen has been used often during anesthesia procedure (Nunes et al, 2011;Paula et al, 2010). However, in dogs anesthetized with propofol (0.7mgkg -1 minute -1 ) and maintained in spontaneous breathing with different FiO 2 (1.0, 0.8, 0.6, 0.4 and 0.21), authors concluded that 60% of oxygen should be used (Nunes et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

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

Lopes¹,

Nunes²,

Belmonte³

et al. 2014

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

“…In this study, FiO 2 of 1.0 was chosen because 100% of the oxygen has often been used during the anesthesia procedure (Leite, 2003;Paula et al, 2010). However, Nunes et al (2008), in a study with dogs submitted to CRI of propofol (0.7mg.kg -1 .minute -1 ) and maintained in spontaneous breathing with different FiO 2 (1.0, 0.8, 0.6, 0.4 and 0.21), concluded that 60% of the oxygen should be used. So, due to this information, FiO 2 = 0.6 was chosen.…”

Section: Discussionmentioning

confidence: 99%

Bispectral index in dogs with high intracranial pressure, anesthetized with propofol and submitted to two levels of FiO2

Lopes

Nunes

Dias

et al. 2011

The effects of inspired oxygen fractions (FiO2) of 1 and 0.6 on bispectral index (BIS) in dogs with high intracranial pressure, submitted to a continuous rate infusion of propofol were evaluated. Eight dogs were anesthetized on two occasions, receiving, during controlled ventilation, an FiO2 = 1 (G100) or an FiO2 = 0.6 (G60). Propofol was used for induction (10mg.kg-1, IV), followed by a continuous rate infusion (0.6mg.kg-1.minute-1). After 20 minutes, a fiber-optic catheter was implanted on the surface of the right cerebral cortex to monitor the intracranial pressure, the baseline measurements of BIS values, signal quality index, suppression ratio number, electromyogram indicator, end-tidal carbon dioxide partial pressure, mean arterial pressure, intracranial pressure and cerebral perfusion pressure were taken. Then, the blood flow from the right jugular vein was interrupted in order to increase intracranial pressure and after 20 minutes additional recordings were performed at 15-minute intervals (T0, T15, T30, T45 and T60). The arterial oxygen partial pressure varied according to the changes in oxygen. For the other parameters, no significant differences were recorded. The BIS monitoring was not influenced by different FiO2.