Radar-based breathing rate monitoring: manikin + human volunteer study

1. Radar-based breathing rate monitoring: manikin + human volunteer study Dave Parry 1 Gary Smith 2 Sheena Farrell 2 David Prytherch 2 Nicholas Hirsch 3 Sarah Harrison 2 Lynsey Woodward 2 University of Portsmouth 1 Portsmouth Hospitals NHS Trust 2 National Hospital for Neurology & Neurosurgery 3

2. Breathing rate • should be routine component of clinical monitoring • is difficult to measure • affected by many clinical states • important predictor of cardiopulmonary arrest, death and readmission to a critical care unit • importance and usefulness often underestimated by clinicians • poor level of breathing rate recording in general hospital wards

3. 30 continuous monitoring 20 10 Nurse Nurse Potential benefits of continuous monitoring of breathing rate Breathing rate Time

4. Radar-based breathing rate monitoring

5. Laerdal BedAlert • device development funded by Laerdal Medical • resources provided by Laerdal Medical • research undertaken jointly by Portsmouth Hospitals NHS Trust and University of Portsmouth

6. Laerdal BedAlert

7. Radar head unit Network cable 1.7 metres PC Controller Laerdal BedAlert: arrangement of study components

8. Laerdal BedAlert: manikin study • simulation study • breathing rate recorded by the BedAlert vs that of an intubated, human manikin lying supine on a standard bed, ventilated using a positive pressure ventilator • measurements were taken at ventilator tidal volumes 150-950 mls • manikin breathing rates varied from 5 to 45 breaths/minute in steps of 5 breaths/minute • each manikin breathing rate kept constant for 5 minutes • average value of the BedAlert breathing rate recorded

9. Laerdal BedAlert: manikin study n = 52 BedAlert breathing rate (bpm) Manikin breathing rate (bpm)

10. Ventilator-driven manikin breathing rate Laerdal BedAlert: manikin study Bland Altman plot of results for all tidal volumes combined Manikin – BedAlert breathing rate Mean difference (bias) = 0.899 bpm SD of the difference (precision) = 0.873 Limits of agreement = +2.61 to -0.812 bpm

11. Laerdal BedAlert: manikin study

12. Laerdal BedAlert: manikin study • the BedAlert radar system gives a clinically acceptable agreement in breathing rate with that of a ventilator-driven human manikin. • no obvious influence of tidal volume on measured breathing rate • in 2002 Lim et al showed inter and intra-observer limits of agreement of +4.4 to -4.2 breaths per minute (experienced clinical staff vs experienced clinical staff).

13. Radar-based respiratory rate monitoring Human volunteer study .

14. Laerdal BedAlert: human volunteer study • 6 human volunteers • computer metronome played repetitive tone at set rate • tone rate 5 – 35 breaths/minute • tone maintained for 2 minutes at each stage • breathing rate simultaneously recorded by BedAlert. • studied in 4 different positions

15. Radar head unit Network cable 1.7 metres PC Controller Laerdal BedAlert: arrangement of study components

16. Laerdal BedAlert: human volunteer study n = 2105 Tone rate (bpm) BedAlert breathing rate (bpm)

17. Laerdal BedAlert: human volunteer study Tone rate – BedAlert breathing rate Mean difference (bias) = 0.010 bpm SD off the difference (precision) = 0.348 Limits of agreement = +0.692 to -0.672 bpm Bland Altman plot of results for all positions

18. Laerdal BedAlert: human volunteer study Bias, precision and limits of agreement for the positions studied

19. Laerdal BedAlert: summary • accurate • painless • non-invasive • safe • radar-based method of measuring breathing rate • potential benefits of continuous monitoring • requires minimal human resources • next steps