Gregory Hare


Associate Scientist, Li Ka Shing Knowledge Institute


Dr. Gregory Hare is a Staff Anesthesiologist at St. Michael’s Hospital and a Professor in the Department of Anesthesia at the University of Toronto. His clinical focus is to develop multimodal and inter-professional approaches to optimize patient outcomes through patient blood management strategies. His long term research goal is to define mechanisms of anemia-induced morbidity and mortality; and to design novel treatment strategies to prevent these adverse outcomes.

Dr. Hare’s research is focused on defining adaptive, and maladaptive, cardiovascular mechanisms in experimental models of acute anemia using integrative whole animal models. These translational studies have defined mechanism of anemia-induced tissue hypoxia and mortality. His laboratory has identified integrative adaptive cellular (nNOS and HIF) and physiological mechanisms which promote organism survival during acute anemia. In addition, their laboratory has demonstrated that acute beta-blockade interferes with adaptive cardiovascular mechanisms, which sustain cerebral oxygen delivery during anemia. This could possibly explain the negative interaction between acute anemia and beta-blockade and the increased incidence of stroke in perioperative patients.

The laboratory is currently focused on translational approaches to identify patient specific biomarkers of anemia-induced tissue hypoxia in order to identify when patients are at risk of anemia induced morbidity and mortality; and to derive patient specific therapies which can reduce morbidity and mortality associated with both anemia and red blood cell transfusion. The overall clinical goal is to reduce morbidity and mortality associated with acute and chronic anemia in perioperative patients.

Recent Publications

  1. Pavenski, K, Ward, SE, Hare, GMT, Freedman, J, Pulendrarajah, R, Pirani, RA et al.. A rationale for universal tranexamic acid in major joint arthroplasty: overall efficacy and impact of risk factors for transfusion. Transfusion. 2018; :. doi: 10.1111/trf.14995. PubMed PMID:30383292 .
  2. Mazer, CD, Whitlock, RP, Fergusson, DA, Belley-Cote, E, Connolly, K, Khanykin, B et al.. Six-Month Outcomes after Restrictive or Liberal Transfusion for Cardiac Surgery. N. Engl. J. Med. 2018;379 (13):1224-1233. doi: 10.1056/NEJMoa1808561. PubMed PMID:30146969 .
  3. Shehata, N, Mistry, N, da Costa, BR, Pereira, TV, Whitlock, R, Curley, GF et al.. Restrictive compared with liberal red cell transfusion strategies in cardiac surgery: a meta-analysis. Eur. Heart J. 2018; :. doi: 10.1093/eurheartj/ehy435. PubMed PMID:30107514 .
  4. McAuliffe, N, Nicholson, S, Rigamonti, A, Hare, GMT, Cusimano, M, Garavaglia, M et al.. Awake craniotomy using dexmedetomidine and scalp blocks: a retrospective cohort study. Can J Anaesth. 2018;65 (10):1129-1137. doi: 10.1007/s12630-018-1178-z. PubMed PMID:29978278 .
  5. Hare, GMT, Han, K, Leshchyshyn, Y, Mistry, N, Kei, T, Dai, SY et al.. Potential biomarkers of tissue hypoxia during acute hemodilutional anemia in cardiac surgery: A prospective study to assess tissue hypoxia as a mechanism of organ injury. Can J Anaesth. 2018;65 (8):901-913. doi: 10.1007/s12630-018-1140-0. PubMed PMID:29696581 .
  6. Mistry, N, Mazer, CD, Sled, JG, Lazarus, AH, Cahill, LS, Solish, M et al.. Red blood cell antibody-induced anemia causes differential degrees of tissue hypoxia in kidney and brain. Am. J. Physiol. Regul. Integr. Comp. Physiol. 2018;314 (4):R611-R622. doi: 10.1152/ajpregu.00182.2017. PubMed PMID:29351418 PubMed Central PMC5966813.
  7. Garg, AX, Shehata, N, McGuinness, S, Whitlock, R, Fergusson, D, Wald, R et al.. Risk of Acute Kidney Injury in Patients Randomized to a Restrictive Versus Liberal Approach to Red Blood Cell Transfusion in Cardiac Surgery: A Substudy Protocol of the Transfusion Requirements in Cardiac Surgery III Noninferiority Trial. Can J Kidney Health Dis. 2018;5 :2054358117749532. doi: 10.1177/2054358117749532. PubMed PMID:29326843 PubMed Central PMC5757433.
  8. Mazer, CD, Whitlock, RP, Fergusson, DA, Hall, J, Belley-Cote, E, Connolly, K et al.. Restrictive or Liberal Red-Cell Transfusion for Cardiac Surgery. N. Engl. J. Med. 2017;377 (22):2133-2144. doi: 10.1056/NEJMoa1711818. PubMed PMID:29130845 .
  9. Kei, T, Mistry, N, Tsui, AKY, Liu, E, Rogers, S, Doctor, A et al.. Experimental assessment of oxygen homeostasis during acute hemodilution: the integrated role of hemoglobin concentration and blood pressure. Intensive Care Med Exp. 2017;5 (1):12. doi: 10.1186/s40635-017-0125-6. PubMed PMID:28251580 PubMed Central PMC5332316.
  10. Levin, DN, Dulberg, Z, Chan, AW, Hare, GM, Mazer, CD, Hong, A et al.. A randomized-controlled trial of nabilone for the prevention of acute postoperative nausea and vomiting in elective surgery. Can J Anaesth. 2017;64 (4):385-395. doi: 10.1007/s12630-017-0814-3. PubMed PMID:28160217 .
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Affiliations & Other Activities


  • Staff Anesthesiologist, Department of Anesthesia, St. Michael’s Hospital
  • Professor, Department of Anesthesia, University of Toronto
  • Professor, Physiology, University of Toronto
  • Associate Member, Institute of Medical Science, University of Toronto