Adv Exp Med Biol
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Comparative Study
Changes in Cerebral Blood Flow and Oxygenation During Induction of General Anesthesia with Sevoflurane Versus Propofol.
Sevoflurane and propofol are widely used for induction and maintenance of general anesthesia. Although the effects of sevoflurane and propofol on cerebral hemodynamics during maintenance of general anesthesia have been demonstrated, the effects during induction of general anesthesia have still not been clarified. We therefore compared changes in cerebral blood flow (CBF) and oxygenation (CBO) during induction of anesthesia using sevoflurane (group S: n=9) or propofol (group P: n=9). ⋯ We found that oxy-Hb, total-Hb, and TOI were significantly higher in group S than in group P (P>0.05). Changes in deoxy-Hb, MBP, and HR did not differ between the groups. The results of the present study demonstrated that sevoflurane increases CBF and CBO during induction of general anesthesia.
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Return of spontaneous circulation (ROSC) during chest compression is generally detected by arterial pulse palpation and end-tidal CO2 monitoring; however, it is necessary to stop chest compression during pulse palpation, and to perform endotracheal intubation for monitoring end-tidal CO2. In the present study, we evaluated whether near-infrared spectroscopy (NIRS) allows the detection of ROSC during chest compression without interruption. We monitored cerebral blood oxygenation in 19 patients with cardiac arrest using NIRS (NIRO-200NX, Hamamatsu Photonics, Japan). ⋯ In addition, we observed abrupt increases of oxy-hemoglobin concentration and tissue oxygen index (TOI), which were associated with ROSC detected by pulse palpation. The present findings indicate that NIRS can be used to assess the quality of chest compression in patients with cardiac arrest as demonstrated by the detection of synchronous waveforms during cardiopulmonary resuscitation (CPR). NIRS appears to be applicable for detection of ROSC without interruption of chest compression and without endotracheal intubation.
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Near-infrared spectroscopy (NIRS) is a widely used non-invasive method for measuring human brain activation based on the cerebral hemodynamic response during gross motor tasks. However, systemic changes can influence measured NIRS signals. We aimed to determine and compare time-dependent changes in NIRS signal, skin blood flow (SBF), and mean arterial pressure (MAP) during low-intensity, constant, dynamic exercise. ⋯ Pearson's correlation coefficients between SBF and O2Hb, and MAP and O2Hb differed in each time phase, from -0.365 to 0.713. During low-intensity, constant, dynamic exercise, the profile of changes in measurements of O2Hb, SBF, and MAP differed. These results suggested that it is necessary to confirm the relationship between O2Hb and systemic factors during motor tasks in order to detect cortical activation during gross motor tasks.
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We studied the level of blood oxygen saturation (SpO2) in the brain in newborn rats in the pre- and post-stroke periods, as well as the changes in cerebral blood flow and beta-arrestin-1 as a marker of hypoxic stress. Our results show that mild hypoxia precedes the stroke development and is associated with venous relaxation and decrease blood outflow from the brain resulting in the elevation of synthesis of beta-arrestin-1 in the brain. The incidence of stroke is characterized by severe hypoxia, which is accompanied by the progression of pathological changes in cerebral veins and the high level of beta-arrestin-1.
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Nanomolar intravascular concentrations of drag-reducing polymers (DRP) have been shown to improve hemodynamics and survival in animal models of ischemic myocardium and limb, but the effects of DRP on the cerebral microcirculation have not yet been studied. We recently demonstrated that DRP enhance microvascular flow in normal rat brain and hypothesized that it would restore impaired microvascular perfusion and improve outcomes after focal ischemia and traumatic brain injury (TBI). ⋯ DRP, injected post insult, increased blood volume flow in arterioles and red blood cell (RBC) flow velocity in capillaries mitigating capillary stasis, tissue hypoxia and BBB degradation, which improved neuronal survival (Fluoro-Jade B, 24 h) and neurologic outcome (Rotarod, 1 week). Improved microvascular perfusion by DRP may be effective in the treatment of ischemic stroke and TBI.