William McKay - Academia.edu (original) (raw)

Papers by William McKay

Canadian Journal of Anesthesia/Journal canadien d'anesthésie, 2019

Anesthesia & Analgesia, 2010

Canadian Journal of Anesthesia/Journal canadien d'anesthésie, 2003

Pediatric Anesthesia, Apr 25, 2023

Canadian Journal Of Anesthesia/journal Canadien D'anesthésie, Jul 4, 2014

Bulletin of anesthesia history, Oct 1, 2009

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society Volume 13: 1991

Page 1. Electrocardiography 15.3-6 A ROBUST QRS-COMPLEX DETECTOR USING AN EQUIVALENCE CLASS CHARA... more Page 1. Electrocardiography 15.3-6 A ROBUST QRS-COMPLEX DETECTOR USING AN EQUIVALENCE CLASS CHARACTERISTIC Peter H. Gregson' and William PS McKay* CV/IP Laboratory, Dept. Elect. Eng. TUNS, Halifax NS, B3H-2W8 Dept. ...

Paediatric anaesthesia, 2016

Muscle & nerve, Jun 27, 2016

We read with great interest the letter by Galassi et al., 1 in which they describe a patient who ... more We read with great interest the letter by Galassi et al., 1 in which they describe a patient who presented initially with isolated primary central nervous system (CNS) lymphoma and after 7 months developed acute demyelinating polyradiculoneuropathy manifesting as generalized muscle weakness, including the bulbar region. The neuropathy remained refractory to immunomodulating/ immunosuppressive therapy, chemotherapy, and radiation therapy. We agree with their recommendation that diffuse large B-cell lymphoma (DLBCL) should be considered in the differential diagnosis of patients with acute demyelinating polyradiculoneuropathy which is refractory to conventional therapy. We have several observations. We would be curious to know what the initial presenting symptom(s) were that led to the stereotactic brain biopsy for the isolated central nervous system lesion. The case report does not state what therapy was given, other than levetiracetam for seizures during the 7 months before the onset of generalized muscle weakness. It is not clear whether the tempo of the weakness was acute like our patient, 2 or subacute/chronic, although the title states it was an "acute neuropathy." It appears that nerve biopsy was not done, unlike in our patient. 2 It may have provided useful information that would have helped distinguish between an immunemediated process and direct infiltration of nerves and vessels by lymphoma cells or vasculitis. 3-5 These are the primary implicated mechanisms for the development of peripheral neuropathy in lymphoma. 3-5 We suggest that a more appropriate term for the diagnosis in the Galassi et al. patient 1 would be acute demyelinating polyradiculoneuropathy/Miller Fisher syndrome (MFS) rather than the generic term "acute peripheral neuropathy" in the title. The described case meets all the clinical, electrodiagnostic, laboratory, and imaging criteria for an acute demyelinating polyradiculoneuropathy/MFS, except that of the atypical lymphocytes in the spinal fluid after multiple examinations, similar to that of our patient. 2

Bulletin of Anesthesia History, 2009

Canadian respiratory journal : journal of the Canadian Thoracic Society

Clinical and investigative medicine. Médecine clinique et experimentale, 1999

To describe a cardiac output measurement using a new method to derive and analyze the long-axis b... more To describe a cardiac output measurement using a new method to derive and analyze the long-axis ballistocardiogram that is less invasive than pulmonary artery thermodilution. Prospective physiologic study. Intensive care unit of The Halifax Infirmary, a teaching hospital of Dalhousie University, Halifax, NS. Thirty-nine patients in sinus rhythm with pulmonary artery thermodilution catheters or radial artery catheters in place. The first 30 subjects were the "learning set" and the next 9 were the "test set." A small (54-g) accelerometer was taped on the patient's chest. Measurements of time and amplitude coordinates of the acceleration and radial artery pressure wavepeaks, as well as anthropometric information. A stroke volume prediction equation was generated (R2 = 0.76) from the learning set. This equation was applied to the test set and correlated with the pulmonary artery thermodilution-derived stroke volumes (R = 0.79). Stroke volumes were compared using ...

Journal of Cardiothoracic and Vascular Anesthesia, 2013

Objectives: To determine whether or not there was a significant difference between the methods of... more Objectives: To determine whether or not there was a significant difference between the methods of centrifugation (CF) and multiple-pass hemoconcentration (MPH) of the residual cardiopulmonary-bypass volume in relation to biochemical measurements and patient outcomes. Design: Prospective, randomized, and controlled. Setting: Conducted at a western Canadian tertiary care hospital. Participants: Consisted of 61 consecutive male and female patients from ages 40 to 80 who were scheduled for cardiac surgery with cardiopulmonary bypass. Interventions: Either the centrifugation or multiple-pass hemoconcentration method was used to process the residual blood from the cardiopulmonary bypass circuit. Results: The 12-hour postoperative levels of serum hemoglobin were not significantly different in the centrifugation group as compared to the multiple-pass hemoconcentration group. However, the serum levels of total protein and albumin were significantly higher in the multiple-pass hemoconcentration group as compared to the centrifugation group. Additionally, after 12-hours postoperatively, the serum fibrinogen and platelet counts were significantly higher in the multiple-pass hemoconcentration group as compared to those of the centrifugation group. The allogeneic product transfusion index and the chest-tube blood drainage indices were lower in the multiple-pass hemoconcentration group as compared to the centrifugation group. Conclusion: Although the CF method provided a product in a shorter turnaround time, with consistent clearance of heparin, the MPH method trended towards enhanced biochemical and clinical patient outcomes over the 12-hour postoperative period.

Evidence Based Nursing, 2012

Implications for practice and research: Intravenous ketamine has been shown to be useful for acut... more Implications for practice and research: Intravenous ketamine has been shown to be useful for acute pain in a variety of settings. The present study shows that it provides a greater reduction in pain than morphine but causes more adverse effects in out-of-hospital care.

European Journal of Applied Physiology, 2007

A number of mechanisms have been proposed to explain the elevation in oxygen consumption followin... more A number of mechanisms have been proposed to explain the elevation in oxygen consumption following exercise. Biochemical processes that return muscle to its pre-exercise state do not account for all of the extra oxygen consumed after exercise (excess post-exercise oxygen consumption, EPOC). Muscle at rest after aerobic exercise produces mechanomyographic (MMG) activity of increased amplitude, compared to the pre-exercise state, which declines exponentially with the same time constant as EPOC. The purpose of this study was to determine how the resting MMG is affected by resistance exercise, and whether any change is related to oxygen consumption (VO(2)). Ten young male subjects (22.9 years) performed 30 min of resistance exercise consisting of one set of 10 repetitions at 50% 1-repetition maximum (1-RM) followed by five sets of eight repetitions at 75% of 1-RM for leg press and leg (knee) extension, with 1 min rest between sets. Oxygen consumption was measured by indirect calorimetry, MMG by an accelerometer placed over the rectus femoris, and surface electromyogram (EMG) with electrodes placed distal to the accelerometer. Recordings were made before exercise and for 5.5 h after exercise. MMG activity, expressed as mean absolute acceleration, was significantly elevated after exercise (P = 0.0006), as was EMG activity expressed as root-mean-square voltage (P = 0.03). MMG and VO(2) demonstrated exponential decay after exercise with similar time constants of 7.5 +/- 2.2 and 7.2 +/- 1.0 min, respectively. We conclude that resting muscle is more mechanically active following resistance exercise and that this may contribute to an elevated VO(2).

European Journal of Applied Physiology, 2006

Mechanomyography has shown that &... more Mechanomyography has shown that "resting" muscle is mechanically active, with greater activity after vigorous exercise. This experiment studied the post-exercise resting mechanomyography activity that results from different levels of exercise; the effects of exercise levels on the contralateral non-exercised limb; and the effects of resting muscle length on post-exercise resting mechanomyographic activity. Ten healthy volunteers had mechanomyography recordings over both mid-rectus femoris, at rest, before and after sets (1, 5, 10, 20, and 30 repetitions) of right leg extensions on an isokinetic dynamometer at 60 s(-1). Sets were performed a week apart, after only sedentary activity during the previous two hours. No definite threshold effect was shown. There was a linear correlation between mechanomyography and work done (R = 0.61, P < 0.01). There was a positive correlation of change of activity between the two thighs (R = 0.62, P < 0.01), with the non-exercised thigh demonstrating about half the activity of the exercised thigh. Finally, we observed that mechanomyographic activity was greater when rectus femoris muscle length was shorter (i.e. when the leg was extended versus flexed). We conclude that resting mechanomyography increases with increasing work and that there is a cross-over for increase in mechanomyography in the non-exercised leg, suggesting a neural mechanism. The greater mechanomyographic activity at shorter muscle lengths suggests that muscle that is less stretched could more freely oscillate, producing higher MMG amplitudes. Altered activity of the muscle spindle gamma loop or Golgi tendon apparatus may also play a role in altered activity with different muscle length.

Acta Anaesthesiologica Scandinavica, 2007

Background: Morphine decreases gut peristalsis, and ketamine decreases morphine use after surgery... more Background: Morphine decreases gut peristalsis, and ketamine decreases morphine use after surgery, and does not slow peristalsis. Thus, the combination should result in faster return of bowel function after surgery than morphine alone. Method: A double-blind randomized controlled trial of saline vs. ketamine with intravenous patient-controlled-analgesia morphine for post-operative pain control was conducted on 42 patients having bowel resection. Bowel function was assessed by auscultation, time to passage of flatus and stool, and time to first retained oral intake; pain by visual analog scale. Time to return of all four measures of bowel function was the primary outcome. Results: Despite a ketamine dose that in other studies had decreased morphine use without side-effects, there was no difference in bowel function, pain control, or morphine use between the two groups. Ketamine resulted in hallucinations in six out of 19 patients, with none in the placebo group (P ¼ 0.018). Conclusion: Low-dose ketamine was not efficacious for hastening return of bowel function, or for decreasing post-operative pain after surgery for bowel resection. It resulted in hallucinations in some patients. Those reporting hallucinations all wished to remain in the study.

Physiological measurement, Jan 23, 2015

Canadian Journal of Anesthesia/Journal canadien d'anesthésie, 2005

Canadian Journal of Anesthesia/Journal canadien d'anesthésie, 2019

Anesthesia & Analgesia, 2010

Canadian Journal of Anesthesia/Journal canadien d'anesthésie, 2003

Pediatric Anesthesia, Apr 25, 2023

Canadian Journal Of Anesthesia/journal Canadien D'anesthésie, Jul 4, 2014

Bulletin of anesthesia history, Oct 1, 2009

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society Volume 13: 1991

Page 1. Electrocardiography 15.3-6 A ROBUST QRS-COMPLEX DETECTOR USING AN EQUIVALENCE CLASS CHARA... more Page 1. Electrocardiography 15.3-6 A ROBUST QRS-COMPLEX DETECTOR USING AN EQUIVALENCE CLASS CHARACTERISTIC Peter H. Gregson' and William PS McKay* CV/IP Laboratory, Dept. Elect. Eng. TUNS, Halifax NS, B3H-2W8 Dept. ...

Paediatric anaesthesia, 2016

Muscle & nerve, Jun 27, 2016

We read with great interest the letter by Galassi et al., 1 in which they describe a patient who ... more We read with great interest the letter by Galassi et al., 1 in which they describe a patient who presented initially with isolated primary central nervous system (CNS) lymphoma and after 7 months developed acute demyelinating polyradiculoneuropathy manifesting as generalized muscle weakness, including the bulbar region. The neuropathy remained refractory to immunomodulating/ immunosuppressive therapy, chemotherapy, and radiation therapy. We agree with their recommendation that diffuse large B-cell lymphoma (DLBCL) should be considered in the differential diagnosis of patients with acute demyelinating polyradiculoneuropathy which is refractory to conventional therapy. We have several observations. We would be curious to know what the initial presenting symptom(s) were that led to the stereotactic brain biopsy for the isolated central nervous system lesion. The case report does not state what therapy was given, other than levetiracetam for seizures during the 7 months before the onset of generalized muscle weakness. It is not clear whether the tempo of the weakness was acute like our patient, 2 or subacute/chronic, although the title states it was an "acute neuropathy." It appears that nerve biopsy was not done, unlike in our patient. 2 It may have provided useful information that would have helped distinguish between an immunemediated process and direct infiltration of nerves and vessels by lymphoma cells or vasculitis. 3-5 These are the primary implicated mechanisms for the development of peripheral neuropathy in lymphoma. 3-5 We suggest that a more appropriate term for the diagnosis in the Galassi et al. patient 1 would be acute demyelinating polyradiculoneuropathy/Miller Fisher syndrome (MFS) rather than the generic term "acute peripheral neuropathy" in the title. The described case meets all the clinical, electrodiagnostic, laboratory, and imaging criteria for an acute demyelinating polyradiculoneuropathy/MFS, except that of the atypical lymphocytes in the spinal fluid after multiple examinations, similar to that of our patient. 2

Bulletin of Anesthesia History, 2009

Canadian respiratory journal : journal of the Canadian Thoracic Society

Clinical and investigative medicine. Médecine clinique et experimentale, 1999

To describe a cardiac output measurement using a new method to derive and analyze the long-axis b... more To describe a cardiac output measurement using a new method to derive and analyze the long-axis ballistocardiogram that is less invasive than pulmonary artery thermodilution. Prospective physiologic study. Intensive care unit of The Halifax Infirmary, a teaching hospital of Dalhousie University, Halifax, NS. Thirty-nine patients in sinus rhythm with pulmonary artery thermodilution catheters or radial artery catheters in place. The first 30 subjects were the "learning set" and the next 9 were the "test set." A small (54-g) accelerometer was taped on the patient's chest. Measurements of time and amplitude coordinates of the acceleration and radial artery pressure wavepeaks, as well as anthropometric information. A stroke volume prediction equation was generated (R2 = 0.76) from the learning set. This equation was applied to the test set and correlated with the pulmonary artery thermodilution-derived stroke volumes (R = 0.79). Stroke volumes were compared using ...

Journal of Cardiothoracic and Vascular Anesthesia, 2013

Objectives: To determine whether or not there was a significant difference between the methods of... more Objectives: To determine whether or not there was a significant difference between the methods of centrifugation (CF) and multiple-pass hemoconcentration (MPH) of the residual cardiopulmonary-bypass volume in relation to biochemical measurements and patient outcomes. Design: Prospective, randomized, and controlled. Setting: Conducted at a western Canadian tertiary care hospital. Participants: Consisted of 61 consecutive male and female patients from ages 40 to 80 who were scheduled for cardiac surgery with cardiopulmonary bypass. Interventions: Either the centrifugation or multiple-pass hemoconcentration method was used to process the residual blood from the cardiopulmonary bypass circuit. Results: The 12-hour postoperative levels of serum hemoglobin were not significantly different in the centrifugation group as compared to the multiple-pass hemoconcentration group. However, the serum levels of total protein and albumin were significantly higher in the multiple-pass hemoconcentration group as compared to the centrifugation group. Additionally, after 12-hours postoperatively, the serum fibrinogen and platelet counts were significantly higher in the multiple-pass hemoconcentration group as compared to those of the centrifugation group. The allogeneic product transfusion index and the chest-tube blood drainage indices were lower in the multiple-pass hemoconcentration group as compared to the centrifugation group. Conclusion: Although the CF method provided a product in a shorter turnaround time, with consistent clearance of heparin, the MPH method trended towards enhanced biochemical and clinical patient outcomes over the 12-hour postoperative period.

Evidence Based Nursing, 2012

Implications for practice and research: Intravenous ketamine has been shown to be useful for acut... more Implications for practice and research: Intravenous ketamine has been shown to be useful for acute pain in a variety of settings. The present study shows that it provides a greater reduction in pain than morphine but causes more adverse effects in out-of-hospital care.

European Journal of Applied Physiology, 2007

A number of mechanisms have been proposed to explain the elevation in oxygen consumption followin... more A number of mechanisms have been proposed to explain the elevation in oxygen consumption following exercise. Biochemical processes that return muscle to its pre-exercise state do not account for all of the extra oxygen consumed after exercise (excess post-exercise oxygen consumption, EPOC). Muscle at rest after aerobic exercise produces mechanomyographic (MMG) activity of increased amplitude, compared to the pre-exercise state, which declines exponentially with the same time constant as EPOC. The purpose of this study was to determine how the resting MMG is affected by resistance exercise, and whether any change is related to oxygen consumption (VO(2)). Ten young male subjects (22.9 years) performed 30 min of resistance exercise consisting of one set of 10 repetitions at 50% 1-repetition maximum (1-RM) followed by five sets of eight repetitions at 75% of 1-RM for leg press and leg (knee) extension, with 1 min rest between sets. Oxygen consumption was measured by indirect calorimetry, MMG by an accelerometer placed over the rectus femoris, and surface electromyogram (EMG) with electrodes placed distal to the accelerometer. Recordings were made before exercise and for 5.5 h after exercise. MMG activity, expressed as mean absolute acceleration, was significantly elevated after exercise (P = 0.0006), as was EMG activity expressed as root-mean-square voltage (P = 0.03). MMG and VO(2) demonstrated exponential decay after exercise with similar time constants of 7.5 +/- 2.2 and 7.2 +/- 1.0 min, respectively. We conclude that resting muscle is more mechanically active following resistance exercise and that this may contribute to an elevated VO(2).

European Journal of Applied Physiology, 2006

Mechanomyography has shown that &... more Mechanomyography has shown that "resting" muscle is mechanically active, with greater activity after vigorous exercise. This experiment studied the post-exercise resting mechanomyography activity that results from different levels of exercise; the effects of exercise levels on the contralateral non-exercised limb; and the effects of resting muscle length on post-exercise resting mechanomyographic activity. Ten healthy volunteers had mechanomyography recordings over both mid-rectus femoris, at rest, before and after sets (1, 5, 10, 20, and 30 repetitions) of right leg extensions on an isokinetic dynamometer at 60 s(-1). Sets were performed a week apart, after only sedentary activity during the previous two hours. No definite threshold effect was shown. There was a linear correlation between mechanomyography and work done (R = 0.61, P < 0.01). There was a positive correlation of change of activity between the two thighs (R = 0.62, P < 0.01), with the non-exercised thigh demonstrating about half the activity of the exercised thigh. Finally, we observed that mechanomyographic activity was greater when rectus femoris muscle length was shorter (i.e. when the leg was extended versus flexed). We conclude that resting mechanomyography increases with increasing work and that there is a cross-over for increase in mechanomyography in the non-exercised leg, suggesting a neural mechanism. The greater mechanomyographic activity at shorter muscle lengths suggests that muscle that is less stretched could more freely oscillate, producing higher MMG amplitudes. Altered activity of the muscle spindle gamma loop or Golgi tendon apparatus may also play a role in altered activity with different muscle length.

Acta Anaesthesiologica Scandinavica, 2007

Background: Morphine decreases gut peristalsis, and ketamine decreases morphine use after surgery... more Background: Morphine decreases gut peristalsis, and ketamine decreases morphine use after surgery, and does not slow peristalsis. Thus, the combination should result in faster return of bowel function after surgery than morphine alone. Method: A double-blind randomized controlled trial of saline vs. ketamine with intravenous patient-controlled-analgesia morphine for post-operative pain control was conducted on 42 patients having bowel resection. Bowel function was assessed by auscultation, time to passage of flatus and stool, and time to first retained oral intake; pain by visual analog scale. Time to return of all four measures of bowel function was the primary outcome. Results: Despite a ketamine dose that in other studies had decreased morphine use without side-effects, there was no difference in bowel function, pain control, or morphine use between the two groups. Ketamine resulted in hallucinations in six out of 19 patients, with none in the placebo group (P ¼ 0.018). Conclusion: Low-dose ketamine was not efficacious for hastening return of bowel function, or for decreasing post-operative pain after surgery for bowel resection. It resulted in hallucinations in some patients. Those reporting hallucinations all wished to remain in the study.

Physiological measurement, Jan 23, 2015

Canadian Journal of Anesthesia/Journal canadien d'anesthésie, 2005