Low Blood Pressure (Hypotension)

Mechanism of Injury

• Once mean arterial pressure moves outside the threshold of autoregulation, cerebral perfusion becomes dependent on blood pressure. In patients undergoing cardiopulmonary bypass, the lower limit of autoregulation can vary widely, from 40 to 90 mmHg([FOOTNOTE=Joshi B, Ono M, Brown C, et al. Predicting the limits of cerebral autoregulation during cardiopulmonary bypass. Anesthesia and analgesia. 2012;114(3):503-510.],[ANCHOR=],[LINK=])
• In circumstances where cerebral perfusion is dependent on blood pressure, it is increasingly likely for even mild hypotension to cause hypoperfusion and ischemia([FOOTNOTE=Ono M, Brady K, Easley RB, et al. Duration and magnitude of blood pressure below cerebral autoregulation threshold during cardiopulmonary bypass is associated with major morbidity and operative mortality. The Journal of thoracic and cardiovascular surgery. 2014;147(1):483-489.],[ANCHOR=],[LINK=])

Associated Outcome

• Gottesman et.al found that an intraoperative mean arterial pressure decrease of >= 10 mmHg from preoperative baseline increased the likelihood of watershed stroke 4.1 times([FOOTNOTE=Gottesman RF, Sherman PM, Grega MA, et al. Watershed strokes after cardiac surgery: diagnosis, etiology, and outcome. Stroke. 2006;37(9):2306-2311. ],[ANCHOR=View Abstract],[LINK=/content/mitg/websites/languagemasters/emea/en-gb/support/clinical-evidence.html?id=883100])