Rohit Malyala’s bio

Rohit Malyala is a fourth-year MD Candidate at the University of BritishColumbia. Prior to medical school, he earned his BHSc. from McMaster University in 2019. He has a passion for working at the nexus of machine learning, classic statistics, and medical device engineering with clinical research to yield actionable insights for the selection and treatment of renal transplant patients, and to optimize post-surgical outcomes in urologic patients.

Determination of blood pressure targets for goal-directed anesthesia in renal transplant

Nick Habibi, Anna-Lisa Nguyen, Erika Escamilla, Lucie Hammond, Hana Mehdic, Sasha Vozynuk, Christopher Nguan

Intraoperative low blood pressure can impact a newly transplanted kidney’s health, but it is unclear how best to characterize this hypotension, and what targets are most appropriate for transplant operations. We thus investigated whether different ways of representing intraoperative mean arterial pressure (MAP) correlated with incidence of delayed graft function (DGF), defined as need for dialysis within one week of transplant.

We characterized intraoperative hypotension as the lowest MAP below various absolute or relative thresholds for a minimum of 5 minutes or 10 minutes just after connecting the kidney to the recipient’s blood supply. Relative thresholds were described in terms of percent MAP drop compared to pre-transplant readings. We used logistic regression to model whether there was a relationship between these methods of describing hypotension, and DGF. We then compared the strength of association between absolute/relative thresholds on DGF incidence using C-statistics. We separated analyses between deceased donation kidneys by cardiac death (DCD), and neurologically-determined death (NDD).

225 patients (81 DCD, 144 NDD) were included, with 71 DGF events. For DCD kidneys, having a lowest absolute MAP below 80mmHg resulted in a near doubling of DGF incidence. Using a 5-minute minimum time-under-threshold, DGF rates increased from 25% at 80-85mmHg versus 57.5% at 70-75mmHg (p=0.127), and using a 10-minute minimum time-under-threshold, 12.5% vs 68.8% for the same thresholds, p=0.029. Lower MAP thresholds progressed towards worse outcomes in DCD kidneys, but no similar hypotension susceptibility was noted in NDD kidneys between 50-90mmHg. Also, using relative thresholds did not improve DGF predictions.

Overall in this early retrospective study, use of relative MAP thresholds in characterizing transplant hypotension did not have any predictive benefit over absolute thresholds. DCD kidneys may benefit from relatively high MAP targets over NDD kidneys.