Meet the Team

THE Lab Directors

Total Health Evaluation Lab Pty Ltd (aka THE Lab) provides specialist Respiratory and Sleep Medicine in Orange NSW and is directed by a group of experienced professionals.

Directors, Dr William Mackie, A/Prof Budhima “Bud” Nanayakkara and Dr Karanvir “KV” Singh work with a team of skilled sleep and respiratory scientists, Medical Specialists, nurses and administration staff to provide a premium service.


A/Prof Budhima Nanayakkara

PhB (Hons) MBBS (Hons) FRACP

A/Prof Budhima “Bud” Nanayakkara is a Sleep and Respiratory Physician, and the medical director of THE Lab. Brought up in Cooma in the Snowy Mountains, Bud has always had a keen interest to practice rural medicine. He completed both his undergraduate and postgraduate medical degree at the Australian National University, with first class honours and the University Medal being awarded for both degrees. Dr Bud completed his Advanced training in Respiratory and Sleep Medicine at The Canberra Hospital and Royal Prince Alfred Hospital where he developed a subspecialty interest in acute and chronic respiratory failure, interstitial lung diseases and pulmonary vascular diseases. He has a strong interest in teaching, and has won awards for teaching medical students, junior doctors and Registrars. He is the Director of Prevocational Education and Training at Orange Health Service. Dr Bud sees all respiratory and sleep medicine patients, including non-respiratory sleep disorders such as narcolepsy, restless leg syndrome and insomnia.


Dr Karanvir Singh


Dr Karanvir “KV” Singh is a Respiratory and General Medicine physician with postgraduate MRCP and CCT from United Kingdom. Dr KV Singh moved to Australia in 2016 and attained FRACP (Australia) while working as a full time Specialist at Orange Health Service. Dr KV Singh has an interest in respiratory conditions like lung cancer, interstitial lung disease, airways diseases and bronchial infections. He started a fast-track lung cancer clinic and restarted Diagnostic/Therapeutic Bronchoscopy along with Endobronchial Ultrasound (EBUS) service at Orange Health Service. Dr KV Singh is the chair of the Western Lung Cancer Working Group and is a core member of Lung Cancer MDT. He has been an Associate Clinical Lecturer with the School of Rural Health, University of Sydney, and has a keen interest in teaching and education.

Ben Nguyen photo2

Dr Ben Nguyen


Dr Ben Nguyen is a Staff Specialist at St Vincent’s Hospital and a Visiting Medical Officer at Royal Prince Alfred Hospital in Sydney. He also works as a Respiratory and Sleep Physician at the Woolcock Institute of Medical Research and is a clinical associate lecturer for the University of Sydney. 

Dr Nguyen completed his respiratory and sleep training at Royal Prince Alfred Hospital, Concord General Repatriation Hospital and Campbelltown Hospital. He completed a sleep fellowship at Royal Prince Alfred Hospital and currently manages a wide variety of sleep disorders including sleep disordered breathing, narcolepsy, parasomnias and restless legs syndrome. He is also interested in seeing patients with a wide range of respiratory conditions and is currently completing a PhD study looking at the effects of positive airway pressure therapy in patients with chronic obstructive pulmonary disease and comorbid sleep disordered breathing.  

Yaroslav Mayorchak

Dr Yaroslav Mayorchak 

MBBS FRACS (Cardiothoracic)                            Minimally Invasive Cardiac and Thoracic Surgeon

Dr Yaroslav Mayorchak is an Australian based Heart and Lung surgeon. Yara is trained in minimally invasive Thoracoscopic and Single port Lung and Heart surgery and has a practice located at Kingswood. Yaroslav has over 12 years of experience practicing in Sydney West and is locally based. Dr Mayorchak is a Cardiothoracic Surgeon at Nepean Private, Nepean public, Hawkesbury, Norwest Private, Westmead public and Prince of Wales Hospitals with extensive experience in Lung Cancer management, cardiac devices and CRT therapy and full spectrum of Heart and Aortic diseases. Dr Mayorchak regularly attends and presents his work at national and international conferences. He pioneered Single port Lung surgery approach in Australia in 2015 and presented his work at Australasian conference in 2017. He contributes to NESQUIP international database and in 2019 his team achieved top 5% results in comparison to other Thoracic units in the USA and developed world.

Dr Mayorchak has authored and co-authored several international publications with 1500 citations. He is an active member of Nepean cancer care centre Lung cancer MDT and Greater West lung Cancer MDT. He completed Cardiothoracic Fellowship placement at Prince of Wales Hospital. Mastered focused minimally invasive Thoracic Fellowship training at St Vincent’s Melbourne and Nepean Hospitals. Acquired FRACS in Cardiothoracic surgery in 2020.

Dr Mayorchak has special interests in: Single port micro invasive lung and mediastinal surgery, Management of end stage lung disease, Lung sparing sleeve resections, Contemporary conventional and minimally invasive Heart surgery, Pacemaker-Defibrillator devices, Bronchoscopic procedures and airway stenting and Single-Port Robotic Surgery.

Dr Sarah Mangalasseril

MBBS RACP RCPA                            

Is a highly qualified and experienced haematologist with extensive training across major tertiary hospitals in NSW including, St George Public Hospital, St Vincent’s Hospital, Westmead Public Hospital, and Liverpool Hospital.

Sarah has expertise in both clinical and laboratory haematology, including the diagnosis and treatment of haematological malignancies such as leukaemia and lymphoma, multiple myeloma and related disorders, clotting and bleeding disorders, iron disorders, inherited blood diseases, pregnancy-related haematologic conditions and blood transfusion management.

She is committed to providing the highest quality, evidence-based care to her patients.

Holding fellowships with both the RACP and RCPA and being an active member of various professional societies and interest groups. Sarah stay's up-to-date with the latest medical evidence and regularly participates in multidisciplinary meetings with colleagues to ensure the best possible treatment decisions for her patients.

She is passionate about providing comprehensive and compassionate care to everyone, and is interested in rural medicine, research, and teaching.

Currently, Sarah is affiliated with Orange Base Hospital as a clinical haematologist and haematopathologist, visits Bathurst Base Hospital and provide haematology advice to the Western NSW Local Health District.

As a haematologist she understands that the best patient-provider relationships are formed through care, connection, trust, and empathy. She strives to ensure good communication and clear instructions with her patients to help them understand their conditions and make informed decisions about their health.

Mrs Katie Nanayakkara

BComm (ANU),  BA (ANU), BSW (CSU) and AMHSW    

Is our behavioural sleep therapist. Katie specialises in Cognitive Behavioural Therapy for Insomnia (CBT-I).

Katie grew up in the Central West and has primarily worked in a regional community mental health setting in the Southern NSW Local Health District. Katie has worked in case management, acute mental health, clinical leadership, and clinical management roles for 10 years before deciding to specialise in Behavioural Sleep. Prior to that she worked in the private sector in assurance and advisory.

Katie is an Accredited Mental Health Social Worker, member of the Australian Association of Social Workers, Affiliate member of the Australian Psychological Society, and is a member of the Society of Behavioural Sleep Medicine. 


Dr Carla Evans

BSc(Hons) PhD

Dr Carla Evans is the Sleep Lab Manager and is responsible for the daily running of the sleep lab.

Carla grew up in North West NSW and spent 20 years in Sydney working in various roles in the Sleep Medicine field.

Carla graduated in 2013 at the University of Sydney with a PhD in Medicine, with her research focusing on paediatric sleep.

Her Sleep Medicine knowledge and experience includes diagnostic and therapeutic sleep study practices for adults and children, clinical research and product development. Prior to moving to Orange, Carla managed a 14-bed sleep lab in Sydney providing clinical and research sleep studies.

Carla is a member of the Australasian Sleep Association, and Australia and New Zealand Sleep Scientist Association.

Carla has returned to regional NSW with a mission to bring “city” Sleep Practice to the region.

Carla is passionate about providing a premium Sleep Lab Service to the regional community.


Mr Clinton Jarman

B Med Sci M Sci CRFS

Clinton Jarman is responsible for the daily running of the Respiratory Lab and performing Lung Function Testing. 

Clinton is a certified respiratory function scientist with more than 20 years of clinical experience spanning across public hospitals, government agencies and private practice.

He holds a BSc (Clinical Physiology) and MSc (Occupational Hygiene Practice).

Get In Touch!

Phone: 02 5350 4690
Fax: 02 6311 1561



Level 3, 1521 Forest Road
Orange NSW 2800