Effect of anesthesia induction on cerebral tissue oxygen saturation in hypertensive patients: an observational study

Abstract

Objective: In hypertensive patients, the autoregulation curve shifts rightward, making these patients more sensitive than normotensive individuals to hypotension. Hypotension following the induction of anesthesia has been studied in normotensive patients to determine its effects on brain tissue oxygenation, but not enough studies have examined the effect of hypotension on brain oxygenation in hypertensive patients. The current study aimed to use near-infrared spectroscopy to evaluate brain tissue oxygen saturation after the induction of anesthesia in hypertensive patients, who may have impaired brain tissue oxygen saturation.

Methods: The study included a total of 200 patients aged > 18 years old with ASA I-III. Measurements were taken while the patient was breathing room air, after the induction of anesthesia, when the lash reflex had disappeared following the induction of anesthesia, after intubation, and in the 5th, 10th, and 15th minutes of surgery. The patients were divided into nonhypertensive and hypertensive groups.

Results: There was a significant difference in age between the groups (p = 0.000). No correlation was found between cerebral tissue oxygen saturation and age (r = 0.015, p = 0.596). Anesthesia induction was observed to decrease mean arterial blood pressure in both groups (p = 0.000). Given these changes, there was no significant difference in brain tissue oxygen saturation between the nonhypertensive and hypertensive groups (p > 0.05).

Conclusion: There was no difference between hypertensive and normotensive groups in terms of the change rates in cSO₂ values. However, there was a difference between the groups in terms of cSO₂ values.

Keywords: Anesthesia induction; Cerebral tissue oxygen saturation; Hypertension.

Figure 1

Vital signs: Comparison of nonhypertensive and hypertensive patients. (●) Comparison between the groups of nonhypertensive and hypertensive patients, p < 0.05; HR, Heart Rate; MAP, Mean Arterial Pressure; SpO₂, Peripheral Oxygen Saturation; EtCO₂, End-Tidal Carbon Dioxide; cSO₂, Cerebral Tissue Oxygen Saturation; T1, First measurement in room air; T2, After the induction of anesthesia; T3, After orotracheal intubation; T4, 5 min after induction; T5, 10 min after induction; T6, 15 min after induction.

Figure 2

The differences between T2 and T1 among all 200 patients. MAP, Mean Arterial Pressure; cSO₂, Cerebral Tissue Oxygen Saturation.