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. 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; :. doi: 10.1152/ajpregu.00182.2017. PubMed PMID:29351418 .
  2. 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.
  3. 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 .
  4. 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.
  5. 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 .
  6. Kosinski, PD, Croal, PL, Leung, J, Williams, S, Odame, I, Hare, GM et al.. The severity of anaemia depletes cerebrovascular dilatory reserve in children with sickle cell disease: a quantitative magnetic resonance imaging study. Br. J. Haematol. 2017;176 (2):280-287. doi: 10.1111/bjh.14424. PubMed PMID:27905100 .
  7. Morrison, MA, Tam, F, Garavaglia, MM, Hare, GM, Cusimano, MD, Schweizer, TA et al.. Sources of Variation Influencing Concordance between Functional MRI and Direct Cortical Stimulation in Brain Tumor Surgery. Front Neurosci. 2016;10 :461. doi: 10.3389/fnins.2016.00461. PubMed PMID:27803645 PubMed Central PMC5067437.
  8. McCredie, VA, Piva, S, Santos, M, Xiong, W, de Oliveira Manoel, AL, Rigamonti, A et al.. The Impact of Red Blood Cell Transfusion on Cerebral Tissue Oxygen Saturation in Severe Traumatic Brain Injury. Neurocrit Care. 2017;26 (2):247-255. doi: 10.1007/s12028-016-0310-6. PubMed PMID:27757915 .
  9. Cahill, LS, Gazdzinski, LM, Tsui, AK, Zhou, YQ, Portnoy, S, Liu, E et al.. Functional and anatomical evidence of cerebral tissue hypoxia in young sickle cell anemia mice. J. Cereb. Blood Flow Metab. 2017;37 (3):994-1005. doi: 10.1177/0271678X16649194. PubMed PMID:27165012 PubMed Central PMC5363475.
  10. Hare, GM. Studying propofol-induced cardioprotection: from mechanism to clinical phenomenon and back again. Can J Anaesth. 2016;63 (4):392-6. doi: 10.1007/s12630-015-0581-y. PubMed PMID:26721647 .
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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