Joseph Fisher

Department of Anesthesiology, University Health Network
Professor, Faculty of Medicine, University of Toronto, Candada
Senior Scientist, Division of Advanced Diagnostics, Cardiovascular
Toronto General Research Institute
Chief Scientist, Thornhill Research Inc.

Research Synopsis

Research Divisions:
Brain Research and Integrated Neurophysiology
Cardiovascular Platform

Research Interests:
The development of novel means for precise control of blood gas partial pressures through ventilation and the applications of this technology to study
a) the vascular components of various neurological and heart diseases and the development of novel imaging methods using magnetic resonance imaging (MRI).
b) the control of the rate of uptake and elimination of various hydrocarbons and other gases through the lungs; specifically, accelerating the elimination of anesthetics and toxins such as carbon monoxide from the body
c) non-invasively determining cardiac output by following the body’s handling of a transient inhalation of a small amount of carbon dioxide
d) adaptation to the scarcity of oxygen at extreme altitude

Keywords: Cardio-pulmonary physiology; vascular reactivity; cerebral vascular disease; coronary vascular disease; hypoxia; hypercapnia; carbon monoxide kinetics; pharmacokinetics of anesthetic vapours.

Detailed Description: 

Over the last 20 years my laboratory has advanced the science of controlling blood gases in spontaneously breathing and ventilated subjects. We have led the way in applying this to advance the understanding of cardio-respiratory physiology and the control of blood flow by the heart and the brain. We have applied our physiological insights to design technology and methods to enhance magnetic resonance imaging (MRI) of structure, to imaging of physiology.  This has led to diagnostic tests that are capable of assessing the neurological and ocular vascular component of a number neurological and ocular diseases.

Our work has translated into actual products with health regulatory approval, that (i) provide life support during war and disaster; (ii) enable anesthesia delivery in the field from a device the size of a small toaster; (iii) enable the assessment of cerebrovascular physiology and assess the risk of stroke and direct clinical interventions; (iv) accelerate the elimination through the lungs of volatile hydrocarbons like carbon monoxide, anesthetics, ethanol and others.

I have a clinical background in anesthesiology and internal medicine. I have supervised approximately 30 graduate students; have authored or co-authored about 220 peer-reviewed publications; have 30 issued patents; and about a dozen patents pending.

METHODS USED

Procedures: Plethysmographic blood pressure; transcranial Doppler, magnetic resonance imaging, breathing circuits controlling arterial blood gases, invasive arterial blood gases, ventilatory parameters, cardiac output via thermodilution and respiratory Fick (non invasive).

EQUIPMENT USED

Computerized gas blender; ECG, MRI, tidal gas partial pressure analyzers; arterial and venous blood gas analyzers; blood pressure transducers; thermodilution catheters and analyzers; MRI; Trans-cranial Doppler; Finger plethysmography; arterial blood gases.

PRESENT TRAINEES

Michael Klein
Sobczyk Olivia
Sam Kevin

PRESENT COLLABORATIONS

Within the Department of Physiology:
James Duffin

Outside the Department of Physiology:
David Mikulis, Radiology/U Toronto/Canada
Rohan Dharmakumar, Cardiology/Cedars-Sinai, Los Angeles CA
Gowland Penny, MRI Physics/U Nottingham/UK
Alan Mutch, Anesthesiology/U Manitoba/Canada
Phil Ainslie, Kinesiology/U British Columbia/Canada
Kelvin Lim, Neuroscience/U Minnesota/USA
Hoge Richard, MRI Physics/U Montreal/Canada

Recent Publications

Retinal arteriolar vascular reactivity response to hypercapnia in young normals assessed with the Canon Laser Blood Flowmeter

Appointments

Primary: Anaesthesia