Comparison of direct and indirect blood pressure in patients under esophagectomy surgery: a prospective observational study

Background: Arterial pressure is one of the most important physiological variables and often needs to be monitored repeatedly or continuously in perioperative period. Arterial pressure monitoring is one of the standard monitoring in operating room. During general anesthesia, blood pressure can be measured by using a noninvasive arterial pressure method or continuous invasive arterial pressure by an invasive arterial line. Comparison of invasive measurements in the patient’s candidate to esophagectomy has not been assessed. The aim of this study was to compare invasive and noninvasive blood pressure in these patients. Methods: In a prospective, cross-sectional, observational study, 42 hemodynamically stable patients candidate for esophagectomy under general anesthesia in supine position were evaluated at Urmia Imam Khomeini Hospital operating room from June 2017 to April 2018. The patients had American Society of Anesthesiologists (ASA) physical status II or III and the patients who had complete heart block and marked arterial blood pressure differences greater than 10  mmHg in the two arms were excluded. After induction of anesthesia and patients monitoring, the radial artery was cannulated for invasive blood pressure monitoring and noninvasive blood pressure was measured via the arm cuff on the other hand at the four-time intervals: after radial artery cannulation (T1), during release of esophagus (T2), during anastomosis (T3) and at the end of operation (T4). Results: The mean difference between indirect and direct systolic blood pressure was 0.85±2.93, -8.42±2.9, 6.50±3.60 and 2.67±2.6 mmHg and for diastolic blood pressure was 3.53±2.67, 4.57±2.22, 2.10±2.58 and 1.03±1.53 mmHg respectively, at the T1 to T4. At the all-time intervals, there were no statistically differences between systolic and diastolic blood pressure measurement regarding invasive and noninvasive blood pressure (P=0.77) Conclusion: Noninvasive arterial blood pressure showed acceptable agreement with invasive measurements for systolic, diastolic and mean pressure. According to fhe finding of this study, there were no statistical differences between systolic and diastolic blood pressure measurement regarding invasive and noninvasive blood pressure and these two methods can be used in selected patients.