Evaluation of the anesthesia depth in experimental animals by parameters of cerebral blood flow and structures of the blood serum solid phase (experimental study)
Abstract
Background. An important pathogenetic step in the development of anesthesia complications is a breathing disorder in the form of apnea, which may transform into agony. However, there are no reports of cerebral blood flow (CBF) during the period of agony. Despite numerous animal studies showing that general anesthesia leads to neurodegeneration and cognitive impairment, there is still no clear consensus on effects of anesthetics in humans.
Aim of the study. To identify markers of anesthesia stages in experimental animals by structures of blood serum (BS) solid phase and by indexes of CBF.
Materials and methods. The study was carried out on sexually mature outbred male rats. The animals were anesthetized with chloral hydrate: control groups received a chloral hydrate dose of 400 mg/kg, i.p., and experimental groups received 500–600 mg/kg, i.p. Blood pressure (BP), CBF, respiratory rate and heart rate were recorded during different phases of anesthesia. CBF was recorded with a LAKK-02 device (LAZMA); BP was measured with a MEC8 Mindray monitor. BS solid phase structures were studied using the method of marginal dehydration on test cards of the “Litos-system” diagnostic kit. BS structures were examined under a microscope in polarized light at a magnification of ×200 and ×400 (DM2500 microscope, Leica).
Results. In the control groups, indexes of CBF, respiratory rate, and heart rate did not significantly differ. In the experimental groups, one hour following administration of the increased anesthetic dose, the heart rate, respiratory rate, and BP were decreased (p < 0.05). Immediately after the onset of apnea, the drop in blood pressure was followed by a rapid decline in CBF. The heart rate amplitude in the spectrum of CBF oscillations was increased three times compared to the control. The time from the apnea onset to zero CBF ranged from 60 to 240 s. Before the drug administration, the BS structures represented spherulites and fan-shaped formations characteristic of the physiological state of the body. During the apnea stage, BS spherulites and fanshaped structures were dotted with many small isotropic inclusions, and also had single small and extensive isotropic faults.
During the agonal stage, most of the BS structural formations represented fragments of spherulites with numerous stripes and branched formations with high anisotropy and multiple faults with corroded boundaries.
Conclusion. The changes in morpho-functional indexes under the action of anesthetics are determined by structural rearrangement of protein molecules as visualized during the BS transformation into the solid phase. The features of BS solid phase pathological structures indicate the anesthesia depth. These changes are consistent with changes in cardiovascular and respiratory parameters in anesthetized animals. The results indicate a possibility of using the analysis of the BS solid phase structures for a retrospective
assessment of changes in CBF, the depth of anesthesia, and side effects caused by various anesthetics in patients. Subsequently, these data may be used for selecting the anesthetic type and its optimum dose for upcoming surgical interventions.
