Non Specific S-T Segment Variations during Intravenous Induction in Anesthesia in Hypertensive Patients Treated with Renin Angiotensin System Antagonists

Abstract

Background: induction in anesthesia and airway‘s manipulations are stressful events for patients undergoing surgery, producing consecutive changes in blood pressure and pulse rate. There are several reports indicating that hypertensive patients treated with Renin angiotensin system (RAS) antagonists show greater hemodynamic changes during these periods which may imply that coronary circulation is compromised and variations in the ST-T segment might be noticed. The aim of this study was to evaluate and report the ST changes appeared during intravenous induction to anesthesia in hypertensive patients.

Method and material: In prospective, randomized clinical study, Sixty patients undergoing elective surgery in general anesthesia, ASA I and II, BMI <30m2 were randomized into two groups: Group A included hypertensive patients, chronically treated with RAS antagonists (n=30) and Group B, included normotensive patients (n=30). Patients in both groups underwent standardized anesthesia induction protocol. In both groups we analyzed the changes of blood pressure, heart rate and non-specific ST changes (smaller than 0.1 mm) at five times: T0 (ambulatory report); T1 –pre induction; T2 – after induction; T3 (at laryngoscopy), T4 (5 min after intubation) and T5 10 min after intubation.

Results: The size of the ST segment at T0 was evidently different in both groups (-0.21mm+0.4 vs. -0.01mm+0.2) but statistically insignificant (p>0.05). At T3 (during the laryngoscopy) there was no differences in the size of the ST segment between the study groups (p=0.07). The main changes were found at T4: -0.31±0.4 vs. -0.02±0.3 (p=0.004427), 5 minutes after the intubation. It seems that this is a result of the stress reaction of the body on the laryngoscopy and due to the effects of the released catecholamines.

Conclusion: The laryngoscopy and the intubation of the hypertensive patients treated with RAS antagonists provoke a remarkable decrease of the BP that is responsible for a coronary vasoconstriction and changes in the size of the ST segment. The main changes in the ST segment are 5 minutes after the intubation.