Feasibility of Structured Light Plethysmography (SLP) in patients with Coronavirus disease 2019 (COVID-19)

The clinical manifestations of COVID-19 range from mild upper respiratory tract illnesses to progressive severe pneumonia, acute respiratory distress syndrome, multi-organ failure, and death. Measures to control the impact of the virus have affected job security, social contact and challenged health services, medical practices and policies. The health service has been radically mobilised to respond to the acute needs of patients infected with the virus at the same time as delivering scaled-back non-COVID-19 healthcare. In many surgical specialties, the management of perioperative patients has changed, with greater focus on remote triage through virtual consultations. However, the pre-operative evaluation of surgical candidates must happen at the clinic. One important aspect of pre-operative evaluation prior to thoracic surgery is pulmonary function testing (PFT), traditionally measured by conventional spirometry.

Understandably, concern has been raised that PFT represents a potential avenue for increased COVID-19 transmission due to increased viral dissemination. The healthcare sector is calling upon novel technology to replace PFT with a non-aerosol-generating alternative.

Structured Light Plethysmography (SLP) (PneumaCare Thora-3Di systems) has been proposed as a novel, non-contact, non-invasive method of assessing lung function. SLP offers real-time regional respiratory function via movement of the chest wall. This detailed information is translated into quantifiable pulmonary function outputs. SLP data may also be used to optimize non-invasive ventilatory settings. SLP has been able to successfully differentiate between the breathing patterns of healthy patients and those with COPD by mapping the thoracoabdominal displacement rate and accurately estimating inspiratory and expiratory flow (1). The ability to continuously measure these parameters may contribute to the safe weaning of patients from ventilatory support. Additionally, we hypothesise that SLP technology will allow clinicians to obtain measurements of breathing patterns that are closer to ecological conditions than those derived from spirometry measurements.

Our centre is currently trialling SLP in the work-up of pre-operative cardiothoracic patients. We feel it is intuitive to use and, therefore, does not require trained technicians, resulting in increased patient throughput and lower costs to the department. Importantly, SLP offers clinicians continuous measurement of mechanical chest wall displacement, a surrogate marker for fatigability and neuromuscular strength.

For the aforementioned reasons, we feel that SLP is a viable alternative to spirometry, especially in the current pandemic. Spirometry remains the gold-standard PFT, however, and the field would certainly benefit from studies evaluating the sensitivity, specificity and clinical validity of SLP in impairment detection, against gold-standard PFT.


Natalie Simon M.Sc. MBBS
Academic Foundation Doctor, Cambridge University NHS Foundation Trust

Manish Soni, MBBS
Specialist Registrar
Bart’s Heart Centre St Bartholomew's Hospital

Trudy Kolvekar, MSc BSc
Bart’s Heart Centre St Bartholomew's Hospital

Amir Khosravi MD MRCS FRCSCTh
Senior Specialist Registrar Bart’s Heart Centre St Bartholomew's Hospital

Shyam Kolvekar MBBS, MS, MCh, FRCPS, FRCS, FRCSCTh
Consultant Cardiothoracic Surgeon Lead, Chest Wall Surgery Bart’s Heart Centre St Bartholomew's Hospital Hon. Associate Professor, University College London. West Smithfield London EC1A 7BE
PA: Rukia Khanom T:02034658689 rukia.khanom@nhs.net s.kolvekar@ucl.ac.uk


  1. Motamedi-Fakhr S, Iles R, Barney A, De Boer W, Conlon J, Khalid A, Wilson RC. Evaluation of the agreement of tidal breathing parameters measures simultaneously using pneumotachography and structured light plethysmography. Physiological Reports. 2017;5(3): e13124 10.14814/phy2.13124