Perioperative Blood Pressure Management

The following data were collected from the electronic medical records and the electronic anesthesia records: age; sex; height; weight; American Society of Anesthesiologists physical status (ASA-PS) classification; comorbidities (heart disease, diabetes mellitus, liver dysfunction, hypertension); use of calcium blocker, renin–angiotensin system (RAS) inhibitors, and psychiatric drugs; preoperative estimated glomerular filtration rate (eGFR) and hematocrit; systolic blood pressure, MAP, and heart rate before 5-ALA intake and before anesthesia induction; detail of the anesthetic procedure; intraoperative minimum systolic and mean blood pressure and heart rate; and use of ephedrine, phenylephrine, dopamine, noradrinaline, and adrenaline. Heart disease was defined as atrial fibrillation (Af), paroxysmal Af, pacemaker implantation, moderate and severe valve disease, history of percutaneous coronary intervention or coronary artery bypass grafting, and history of heart failure. We defined the blood pressure and heart rate before anesthesia induction as those when entering the operating room.
The primary outcome was the incidence of post-induction hypotension. We defined post-induction hypotension as follows: (1) MAP < 60 mmHg in accordance with a recent review article [9 (link)], (2) during the first 1 h after anesthesia induction, (3) anesthesia induction was defined as initiation of oxygenation in general anesthesia and spinal injection in spinal anesthesia, and (4) from anesthesia induction to just before positional change, if a positional change from a supine to a prone or lateral recumbent position was performed during the first hour in craniotomy (Fig. 1). Then, we divided the participants into two groups, namely, the normal blood pressure group (group N) and the hypotension group (group L).
Fig 1

Definition of post-induction period and timing of blood pressure measurement. We defined post-induction period as the initial 60-min period taking place immediately after anesthesia induction. Starting anesthesia (0 min) was initiation of anesthesia induction. If a positional change from a supine to a prone or lateral recumbent position was performed during this 60 min in craniotomy, the study period was then defined as the time from anesthesia induction to just before the positional change. ALA, 5-aminolevulinic acid; OR, operating room; BP1, blood pressure before 5-ALA intake; BP2, blood pressure when entering operating room (before anesthesia induction); BP3, blood pressure during post-induction period