Different preoperative fluids do not affect the hemodynamic status but gastric volume: results of a randomized crossover pilot study.

BACKGROUND AND OBJECTIVE: Inferior vena cava (IVC) examination has been reported as a noninvasive method for evaluating the hemodynamic state. We conducted this crossover pilot study to investigate the effects of the administration of water and high-carbohydrate-containing fluids on the hemodynamic status of volunteers through collapsibility index of IVC (IVCCI) measurement. METHODS: Twenty volunteers were randomly assigned to a water or high-carbohydrate group according to computer-generated random numbers in a 1:1 ratio. In the water group, volunteers received water (5 mL/kg), and in the high-carbohydrate group, patients received carbohydrate drinks (5 mL/kg). Respiratory variations in the IVC diameter, gastric volume, and blood pressure and heart rates in erect and supine positions were measured at admission (T1), 1 h (T2), 2 h (T3), 3 h (T4), and 4 h (T5). RESULTS: When considering participants with an IVCCI of more than 42%, there were no significant differences between the water and carbohydrate drink groups at each time point (all p > 0.05). At T2, more participants had an empty stomach in water group than in carbohydrate drink group (p < 0.001). At T3, 30% of the participants could not empty their stomachs in carbohydrate drink group. However, with regard to the number of volunteers with empty stomach at T3, there was no significant difference between water and carbohydrate drink group. Repeated measures data analysis demonstrated that IVCCI showed no significant differences over time (p = 0.063 for T1-T5). There were no differences between water and carbohydrate drinks (p = 0.867). CONCLUSION: Our results suggested that neither water nor carbohydrate drinking affected the hemodynamic status through IVCCI measurement over time, up to 4 h after drinking. Furthermore, carbohydrate drinking might delay gastric emptying at 1 h, but not 2 h after drinking, in comparison with water.

Normobaric hyperoxia retards the evolution of ischemic brain tissue toward infarction in a rat model of transient focal cerebral ischemia.

OBJECTIVES: Oxygen therapy has been long considered a logical therapy for ischemic stroke. Our previous studies showed that normobaric hyperoxia (normobaric hyperoxia (NBO), 95% O2 with 5% CO2) treatment during ischemia reduced ischemic neuronal death and cerebromicrovascular injury in animal stroke models. In this study, we studied the effects of NBO on the evolution of ischemic brain tissue to infarction in a rat model of transient focal cerebral ischemia. METHODS: Male Sprague-Dawley rats were given NBO (95% O2) or normoxia (21% O2) during 90-min filament occlusion of the middle cerebral artery (MCAO), followed by 3 or 22.5 h of reperfusion. 2,3,5-triphenyltetrazolium chloride (TTC) staining was used to evaluate the longitudinal evolution of tissue infarction. Results： In normoxic rats, MCA-supplied cortical and striatal tissue was infarcted after 90-min MCAO with 22.5 h of reperfusion. NBO-treated rats showed a 61.4% reduction in infarct size and tissue infarction mainly occurred in the ischemic striatum. When infarction was assessed at an earlier time point, i.e. at 3 h of reperfusion, normoxic rats showed significantly smaller but mature infarction (no TTC staining, white color), with the infarction mainly occurring in the striatum. Unexpectedly, NBO-treated rats only showed immature lesion (partially stained by TTC, light white color) in the ischemic striatum, indicating that NBO treatment also retarded the process of neuronal death in the ischemic core. Of note, NBO-preserved striatal tissue underwent infarction after prolonged reperfusion. Conclusions： Our results demonstrate that NBO treatment given during cerebral ischemia retards the evolution of ischemic brain tissue toward infarction and NBO-preserved cortical tissue survives better than NBO-preserved striatal tissue during the phase of reperfusion.

Hypertonic/hyperoncotic solution attenuate blood-brain barrier breakdown and brain pathology in whole body hyperthermia rats.

This study was designed to investigate the effects of hypertonic/hyperoncotic solution on blood-brain barrier damage, brain edema and morphological changes of rats during whole body hyperthermia. 90 adult male Sprague-Dawley rats were randomized into 5 groups: Control group (a room temperature for 4 hours); Whole body hyperthermia group without solution treatment; Whole body hyperthermia group with Ringer's solution treatment; Whole body hyperthermia group with hydroxyethyl starch and Ringer's solution treatment; Whole body hyperthermia group with Hypertonic/hyperoncotic solution treatment. All rats except those of control group were housed in a heated container and maintained at 36°C for 3 hours until the rectal temperature reached 41-42°C. Corresponding solutions were administered intravenously at the beginning of whole body hyperthermia within 30 minutes as designed. Following whole body hyperthermia, rats were subsequently cooled down for 1h. Evans blue was administered intravenously when the rectal temperature was cooled down to 37°C. The leakage of Evans blue-albumin and water content of brain were calculated and morphological changes were investigated. In group with hypertonic/hyperoncotic solution treatment, brain water content and the leakage of Evans blue-albumin were the lowest among the four whole body hyperthermia groups. Compared with the other three whole body hyperthermia groups, in which profound to moderate damages to blood-brain barrier and brain tissue and cells were found, there were only slight morphological changes in the group with hypertonic/hyperoncotic solutionon treatment. Treatment with hypertonic/hyperoncotic solution appeared to attenuate the injury to blood-brain barrier and reduce brain edema and cell morphological changes in whole body hyperthermia rats.

[Effects of hypertonic sodium chloride hydroxyethyl starch 40 on brain histopathology in rats with whole body hyperthermia].

OBJECTIVE: To investigate the effects of hypertonic sodium chloride hydroxyethyl starch 40 (HSH) on brain edema and morphological changes during whole body hyperthermia (WBH) in rats. METHODS: Sixty adult male SD rats were randomized into control group, WBH group without fluid infusion (group HT), WBH group with Ringer's infusion (group RL), WBH group with HAES + Ringer's infusion (group HRL) and WBH group with HSH infusion (group HSH). WBH was induced by exposure to 36 degrees celsius; for 3 h to achieve a rectal temperature of 41-42 degrees celsius;, and the corresponding fluids were administered intravenously within 30 min at the beginning of WBH. The control rats were housed at a controlled room temperature (22∓1) degrees celsius; for 4 h. After cooling at room temperature for 1 h, the rats were sacrificed and brain water content and morphological changes were evaluated. RESULTS: Compared with the control group, all the WBH groups had significantly increased brain water content (P<0.05 or 0.01), but group HSH showed a significantly lower brain water content than group HT (P<0.05). The rats in groups HT, RL and HRL showed serious to moderate structural changes of the brain tissue and nerve cells, but HSH group had only mild pathologies. CONCLUSION: HSH can reduce brain edema and ameliorate the damages to brain cells in rats exposed to WBH.

[Reproduction of a murine model of hyperthermic treatment].

OBJECTIVE: To find out the most suitable conditions for a whole body hyperthermia (WBH) model and the influence of these conditions on the blood brain barrier (BBB) disruption and brain edema in rats. METHODS: Forty male Sprague-Dawley (SD) rats were randomly assigned to four groups (n=10 in each group): control group, group A, group B and group C. After anesthesia with pentobarbital, rats were subjected to femoral artery and vein cannulation. Rats of control group were housed at a controlled room temperature (25-26 degrees C) for 4 hours. Rats of group A, group B and group C were exposed to WBH in a biological oxygen supply heated container (relative humidity 65%, wind velocity 25 cm/s) maintained at 34, 36 and 38 degrees C for 3 hours, respectively. Then the rats were removed from the heated container and their body temperature was cooled down for 1 hour. During heating, rectal temperature, heart rate (HR), mean arterial pressure (MAP), pH, partial pressure of oxygen in artery (PaO(2)), partial pressure of carbon dioxide in artery (PaCO(2)), the dosage of anesthetic, and the mortality rate in each group were recorded. Evans blue (EB) was administered into the femoral vein and allowed to circulate for 5 minutes. At the end of the experiment, the animals were perfused with 0.9% saline and heparin through the heart, and the brain was harvested for the examination of BBB permeability, water content and morphological alterations in brain tissues and neurons. RESULTS: The total dosage of pentobarbital was not significantly different among all groups. After WBH for 3 hours, the average rectal temperature was higher than rats without WBH, and the mortality rate was 0, 10%, 10% and 40% in groups control, A, B, C, respectively. HR of groups A, B and C were significantly higher than those of control group; MAP, pH of group A, B and C were significantly lower than those of control group (all P<0.05). Compared to that of control group, water content of the brain and permeability of EB in groups A, B and C were significantly increased (P<0.05 or P<0.01), but there was no marked difference on PaO(2), PaCO(2) and haematocrit (HCT) among groups A, B and C. Morphological investigation showed that there were different degrees of structural changes in brain tissue in groups A, B and C under light microscopy. Under transmission election microscopy, the structure of nerve cells and BBB in group B and group C showed moderate to profound alterations, but there were no changes in group A. CONCLUSION: Rats housed in a biological oxygen supply heat container with the temperature maintained at 36 degrees C for 3 hours could establish an ideal WBH model with notable BBB breakdown, moderate brain edema, and histological changes in brain.