The Influence of spinal anesthesia and body positioning on cerebral blood flow and hemodynamics

Abstract

Background: Spinal anesthesia is commonly used in herniated lumbar disc surgery, during which prone position of the patient is necessary. It is thought that this position can increase intraabdominal pressure. Both spinal anesthesia and increased intraabdominal pressure can have an effect on the systemic and cerebral blood flow dynamics. The goal of this study was to evaluate the cerebral blood flow changes in patients prior to and after spinal anesthesia in different body positions. Methods: The study was carried out in a teaching hospital during a six month period in 2016. Cerebral blood flow dynamics in middle cerebral artery were registered using transcranial Doppler for patients undergoing herniated lumbar disc surgery under spinal anesthesia. The measurements were made in 4 timepoints: prior to spinal anesthesia (1),10 minutes after the local anesthetic injectionin lateral position (2), after placing the patient in prone position (3) and after placing the abdomen supporting frame beneath the patient (4). Demographic data were collected. Statistical analysis was carried out using Chi-Square and Krustkal-Wallis tests. Results: Overall, 70 patients were included in the study. All of the patients fit the criteria for ASA I-III, mean age 48.4±12.2 years. Comparing 1st and 2ed measurement points systolic 132.4±21.7 mmHg117.5±17.5, diastolic 72.3±12.166.7±9.6 and mean arterial pressure (MAP) 96.5±13.886.7±11.5 decreased statistically significantly (p=0.000, p=0.001 and p=0.000 accordingly). After the patient was placed in a prone position (between 2ed and 3rd measurement points) systolic flow velocity decreased 89.3±18.9 cm/s83.0±18.9 (p=0.047), but the diastolic 66.7±9.670.8±12.4 (p=0.016) and MAP 86.7±11.590.7±12.5 (p=0.037) grew. Following the frame for abdomen support placement (between 3rd and 4th measurement points) the resistance index increased 0.510±0.060.512±0.05 (p=0.000)