Associate Professor
Critical Care Medicine
Research Interests:

I joined the Faculty of Medicine (Respiratory Division) at the University of British Columbia in September 2002 after completing my clinical and research training at Harvard Medical School. I subsequently joined the Critical Care Division. My broad area of research interest involves the investigation of the public health and safety consequences of sleep disorders, including both respiratory sleep disorders (such as sleep apnea) and sleep deprivation. I have received peer-reviewed research funding from a number of national and provincial agencies (including a Scholar Award from the Michael Smith Foundation and operating grants). I have lectured extensively locally, nationally, and internationally on a variety of sleep-related topics.

My research accomplishments over the last five years include the following:

1) ICU Patient Safety; Healthcare Worker Fatigue and Patient/Occupational Safety: I have continued and expanded research related to the effects worker fatigue on safety. First, as part of the Harvard Workhours and Safety Group, we have examined the impact of extended duration (on call) shifts on a variety of adverse outcomes including motor vehicle crashes (see Barger et al NEJM 2005), percutaneous injuries (Ayas et al JAMA 2006), and medical errors (Barger et al PLOS Medicine 2006) using a large epidemiologic cohort of interns. Furthermore, I have received funding from the Canadian Patient Safety Institute to perform an in-depth study of the effects of resident fatigue on resident performance using the high fidelity simulator at VGH; this was presented as an abstract at the recent International Conference on Residency Education (Sept 2008) where it was selected as the best abstract at the Simulation Summit. With Peter Dodek, I am a co-PI of a MSFHR grant to study safety outcomes in the intensive care unit. Although my main interest is to study the relationship between work schedules (nurse, physician, etc) on these safety outcomes (see Louie et al, submitted Chest), I have also been involved with a number of there project related to quality improvement/health services research in the ICU (e.g., Ayas et al Quality and Safety in Healthcare 2007, Mountain et al 2009, Wilmer et al 2009, Khan et al Chest 2008).

2) Sleep Apnea Clinical Research Registry: We have developed an ongoing registry of patients who have overnight sleep studies at the University of British Columbia sleep laboratory (funded by MSFHR and BC Lung Association). Thus far, detailed physiologic  and survey data have been collected from approximately 2000 patients. Furthermore, 500 patients have had blood samples taken, centrifuged, and frozen (aliquots of plasma, serum, and genetic material). Preliminary analyses have been performed to examine relationships between work productivity, sleepiness, motor vehicle crashes, and sleep apnea (Mulgrew et al, Thorax  2008 and Sleep Medicine 2008). We are in the process of linking our registry to other provincial databases (Workers Compensation Board, Medical Services Plan, etc) to assess the impact of sleep apnea on a variety of outcomes (motor vehicle crashes, work injuries) and have generated preliminary data in this regard (AlLawati et al. APSS 2008). Finally, we have performed preliminary analyses to assess inflammatory markers using stored serum (see Mulgrew et al, ATS abstract 2006). Prospective analyses are ongoing.

3) Economics of Sleep Apnea: One of my major research interests has been the study of economic issues related to sleep apnea. This has included use of the Registry (see 1) above) to assess the impact of sleep apnea on work productivity. Furthermore, we have recently completed a comprehensive cost-effectiveness analysis of therapy for sleep apnea (Ayas et al, Archives of Internal Medicine 2006), and performed a similar analysis from the Canadian perspective (Tan et al, Canadian Respiratory Journal 2008). Finally, we have recently completed a randomized trial to test various strategies to diagnose/manage patients with sleep apnea (Mulgrew et al Annals Internal Medicine 2007).

4) Meta-analysis: I have been involved in meta-analysis on varied of sleep, respiratory, and critical care topics topics including the effectiveness of sleep apnea therapies such as CPAP (Patel et al Archives Internal Medicine 2003) and auto-titrating (smart) PAP (Ayas et al Sleep 2004). Oftentimes, I have encouraged and supervised residents and fellows in clinical programs to participate in these studies (see Wang et al JAMA 2005; Davidson et al Critical Care 2006; Bajwa et al Chest 2005; AlAjmi et al Lung 2008).

5) Assessment of New Technology in the Diagnosis and Treatment of Sleep Apnea: I have been involved in a number of trials to assess new technologies in the field of sleep apnea. This has included the use of complex data mining techniques (in collaboration with SFU Computer Science Department- see Kwiatkowska et al, Transactions on Information Technology in Biomedicine, in review), peripheral arterial tonometry (Ayas et al Sleep Medicine 2003, Pittman et al Sleep 2004), nasal pressure recordings (Almeida et al Sleep and Breathing 2006), and novel positive airway pressure devices (Mulgrew et al Sleep and Breathing in press).

6) Sleep Habits and Chronic Health Outcomes: Using the Nurses’ Health Study cohort, we have completed a number of studies that have documented significant independent associations between sleep habits and incident cardiovascular disease (Ayas et al Archives Internal Medicine 2003), diabetes (Ayas et al Diabetes Care 2003), and mortality (Patel et al, Sleep 2004).

Combined Program in Pulmonary & Critical Care Harvard, Boston, MA
Masters, Harvard School of Public Health
MD, University of Alberta
Recent Publications:
  • 2006 Ayas NT, Barger LK, Cade BE, Hashimoto D, Rosner B, Cronin JW, Speizer F, Czeisler CA. The impact of extended duration workshifts on percutaneous injuries in interns. JAMA 2006. 296:1055-62.
  • 2006 Ayas NT, FitzGerald JM, Fleetham J, Schulzer M, White DP, Ryan CF, Ghaeli R, Mercer GW, Marra CA. Cost-Effectiveness of Continuous Positive Airway Pressure (CPAP) for Moderate to Severe Obstructive Sleep Apnea Hypopnea. Archives Internal Medicine 2006. 166: 977-84.
  • 2006 Barger LK, Ayas NT, Cade BE, Cronin JW, Rosner B, Speizer F, Czeisler CA. Impact of Extended Duration Work shifts (>24 hours) on Significant Medical Errors, Preventable Adverse Events, and Attentional Failures. In press, PLOS Medicine.
  • 2006 Davidson WJ, Dorscheid D, Spragg R, Schulzer M, Mak E, Ayas NT. Exogenous Pulmonary Surfactant for the Treatment of Adult Patients with Acute Respiratory Distress Syndrome – Results of a Meta-Analysis. Crit Care. 2006 Mar 8;10(2):R41. (Epub ahead of print).
  • 2006 De Almeida FR, Ayas NT, Otsuka R, Hamilton P, Ryan CF, Lowe A. Nasal Pressure Recordings to Detect Obstructive Sleep Apnea. Sleep Breath. 2006. 10:62-69.
  • 2006 Landrigan CP, Barger LK, Cade BE, Ayas NT, Czeisler CA. Interns’ Compliance with Accreditation Council for Graduate Medical Education Work-Hour Limits. JAMA 2006. 296:1063-70.
  • 2006 Lusina SC, Paul MK, Inglis JT, McKenzie DC, Ayas NT, Sheel W. Long Term Intermittent Hypoxia Increases Sympathetic Activity and Chemosensitivity During Acute Hypoxia in Humans. Journal of Physiology 2006. Epub ahead of print.
  • 2007 Alajmi M, Mulgrew A, Fox J, Davidson W, Schulzer S, Mak E, Fleetham J, Ayas NT. The Impact of Continuous Positive Airway Pressure (CPAP) Therapy on Blood Pressure (BP) in Patients with Obstructive Sleep Apnea (OSA): A Meta-analysis of Randomized Controlled Trials. Lung 2007. 185: 67-72.
  • 2007 Ayas NT, Norena M, Wong H, Chittock D, Dodek PM. Pneumothorax after central venous catheter placement in the ICU: Impact of month of year and week of month. Quality and Safety in Healthcare 2007. 16:252-255.
  • 2007 Kwiatkowska M, Atkins MS, Ayas NT, Ryan CF. Knowledge-based data analysis: First steps towards the creation of clinical prediction rules, using a new typically measure. IEEE Trans Inf Technol Biomed. 2007. 11(6):651-60.
  • 2007 Mulgrew AT, Cheema R, Fleetham J, CF Ryan, Ayas NT. Efficacy and Patient Satisfaction with Auto-adjusting with variable Expiratory Pressure vs. Standard CPAP: A Randomized Cross-over Trial. Sleep and Breathing 2007. 11:31-7.
  • 2007 Mulgrew AT, Fox N, Ayas NT, Ryan CF. Diagnosis and initial management of obstructive sleep apnea without polysomnography: a randomized validation study. Annals of Internal Medicine 2007. 146:157-166.
  • 2008 Mulgrew A, FitzGerald JM, Fox N, Ryan CF, Marra C, Koehoorn M, Jung D, Chambers K, Fleetham J, Ayas NT. The Impact of Obstructive Sleep Apnea and Sleepiness on Work Limitation. Sleep Medicine 2008. 9:42-53.
  • 2008 Mulgrew A, Nasvadi G, Butt A, Cooper P, Fleetham J, Ryan F, Jung D, Ayas N. Risk and severity of Motor Vehicle Crashes in Obstructive Sleep Apnea Patients. Thorax 2008. Epub ahead of print.
  • 2009 AlLawati N, Mulgrew A, Cheema R, VanEeden S, Butt A, Fleetham J, Ayas N. Pro-atherogenic cytokine profile of patients with suspected obstructive sleep apnea. Sleep and Breathing 2009. 13: 391-5.
  • 2009 Mountain S, Hameed M, Dodek P,  Ayas N, Norena M, Chittock D, Wong H. Effect of ICU Workload as Reflected by ICU Activity on Mortality and Time to discharge Alive from ICU. Healthcare Quarterly 2009; 12: 8-14.
  • 2009 Sadatsafavi M, Marra CA, Ayas NT, Stradling JR, Fleetham JA. Cost-effectiveness of Oral Appliances in treatment of Obstructive Sleep Apnea-Hypopnea. Sleep and Breathing 2009. 13:241-52.
  • 2009 Wenner J, Norena M, Khan N, Palepu A, Ayas N, Wong H, Dodek P. Reliability of ICU Admitting and Comorbid Diagnoses, APACHE II score, and Race in an Electronic ICU Database. Journal of Critical Care 2009. 24: 401-7.
  • 2010 Ayas NT, Fox J, Epstein L, Ryan CF, Fleetham JA. Initial Use of Portable Monitoring Versus Polysomnography to Confirm Obstructive Sleep Apnea in Symptomatic Patients: An  Economic Decision Model.S Ileep Medicine  2010; 11:320-4.
  • 2010 Hirsch-Allen AJ, Ayas N, Mountain S, Dodek P, Peets  A, Griesdale DE. Influence of residency training on multiple attempts at  endotracheal intubation. Can J Anaesth 2010. 57: 823-9.
  • 2010 Louie K, Cheema R, Dodek P, Wong H, Wilmer A, Grubisic M, FitzGerald JM, Ayas NT. Nursing work schedules and the risk of hypoglycemia in critically ill patients receiving intravenous insulin. Quality and Safety in Healthcare 2010. 19:e42.
  • 2010 Louie KE, Wilmer A, Wong H, Grubisic M, Ayas N, Dodek P. Medication error reporting systems: A survey of Canadian Intensive Care Units. In press, Canadian Journal of Hospital Pharmacy.
  • 2010 Mulgrew AT, Lawati NA, Ayas NT, Fox N, Hamilton P, Cortes L, Ryan CF.Residual sleep apnea on polysomnography after 3 months of CPAP therapy: clinical implications, predictors and patterns.  Sleep Med. 2010;11:119-25.
  • 2010 Sharpe R, Koval V, Ronco JJ, Qayumi K, Dodek P, Wong H,  Shepherd J, FitzGerald JM, Ayas NT. The Impact of Prolonged Continuous Wakefulness on Resident Clinical Performance in the Intensive Care Unit: A Patient Simulator Study.  Critical Care Medicine. 2010; 38: 766-770.
  • 2010 Wilmer A, Louie K, Dodek P, Wong H, Ayas NT. Methods for detecting adverse events and medical errors in the ICU: A Systematic Review. Quality and Safety in Healthcare 2010. 19:e7.