- In this retrospective review the authors developed a model to predict preoperatively which mean arterial pressures (MAPs) would have the lowest risk of intraoperative hypotension (IOH) based on each patient’s unique risk factors.
- A total of 161,000 surgeries were studied with 7.3 million MAP measurements. These were divided into 2 groups which consisted of 121,000 in the training group and 45,000 in the validation group. There were a total of 36 subgroups that represented 92% and 94% of the total MAP measurements. Five different models were tested to find the best fit.
- The subgroups consisted of emergency or elective surgery, age, sex, and ASA status. MAPs between 65-100 mmHg were tested to define IOH risk.
- Although historical benchmarks would indicate that MAPs > 65 mmHg were an acceptable target to prevent IOH, this study clearly shows that there are differences for various patient groups. For instance, in an elective case with an ASA 3, male, and age >66 years, a target MAP of >82 mmHg was required to be in the low-risk group for IOH.
- This study has several important patient safety implications:
- First, compared to the historical target of 65 mmHg, the model provides the clinician patient-specific target MAPs that are predicted to reduce the IOH risk. The risk of IOH rapidly increases as the MAP approaches 65 mmHg, particularly in the high-risk groups.
- Second, even relatively small differences in pressure can result in a large increase in IOH risk, particularly as the MAP neared 65 mmHg. For instance, across all subgroups, a MAP of 70 mmHg when compared to a MAP of 80 mmHg resulted in almost a 4-fold increase in IOH risk.
- Third, the target MAPs do not indicate an ideal pressure, since baseline BP, autoregulation, and clinical assessment must also be accounted for. The model does provide the clinician with information on predicting IOH risk and increase their ability to act sooner to prevent IOH and possible end-organ damage.
Summary of "Preoperative Identification of Patient-Dependent Blood Pressure Targets Associated With Low Risk of Intraoperative Hypotension During Noncardiac Surgery"
Summary published February 25, 2023