Validation against direct airflow measurements

FloRight has been validated against direct airflow measures registered using mask-based systems. Masks introduce an extra volume of air, may leak air, require an additional breathing effort and may require sedation. Different mask systems moreover provide diverging values, and FloRight does not precisely replicate the values provided by any one mask system. The output values provided by FloRight were comparable to the median output of mask-based systems that were reviewed.

FloRight was found to be a suitable device to monitor trends and changes in pulmonary function, and has been suggested as a more suitable indicator of "true" values of pulmonary function in neonatal patients. VoluSense does not claim that the FloRight system confirms or establishes absolute values of tidal flow, tidal volume or other pulmonary function measures.

FloRight was found to be:
- suitable for lung function assessment including thoraco-abdominal asynchrony.
- compatible with ventilation, CPAP and nasal cannula systems.
- helpful to see and evaluate the pulmonary function impact of Bronchopulmonary Dysplasia.
- non-invasive, mask free (including during system calibration) and exceptionally well tolerated by premature babies down to at least 27 weeks gestation.

A clinical trial summary and publication abstracts follow below. Clinicians interested in trial use or preorders are welcome to contact us.

Clinical investigators and advisors

- Prof. Michael Davis, PhD, Paediatric respiratory medicine, Montreal children's hospital, Canada.
- Prof. Dr Med Urs Frey, PhD, Head Dept. of paediatric respiratory medicine, Bern University Children's Hospital, Switzerland.
- Associate Prof. Graham Hall, PhD, School of peadiatrics and child health, University of Western Australia.
- Dr Med Thomas Halvorsen, Children's center, Haukeland university hospital, Bergen, Norway.
- Prof. Sailesh Kotecha, Prof. of child healh, Wales College of Medicine, Cardiff University, UK.
- Dr Paul Seddon, Royal Alexandra Children Hospital, Brighton, UK.

Clinical trial summary

In chronological order:

Oslo (I)	- Proof of concept, vest selection for electromagnetic measurement.
Göteborg	- Performance at par with gold standard i.e. plethysmograph + mask. (Larger study needed.)
Oslo (II)	- Unique volumetric profile for Respiratory Syncytial Virus infection. (Larger study needed.)
Brighton	- Clear distinction Bronchopulmonary Dysplasia patients and healthy infants. - Allows lung function assessment including thoraco-abdominal asynchrony. - See Olden et al. (2010)
Bern	- Absolute tidal volume measurements lower than mask standard; logically less exertion without mask. - Allow infant to lie on mattress for measurement stability, not in parent's arms. - Potential in apnea detection, Bronchopulmonary Dysplasia vs healthy, sleep stage monitoring.
Cardiff (I)	- Enables realistic, accurate and continuous measure of tidal flow, ventilation, breathing patterns in infants down to at least 27 wk gestation. - Well tolerated, no interference with care. Possible to use in neonates on ventilation, CPAP, nasal cannula. No sedation need. - Larger study needed for quantified decision support on weaning of CPAP or titration of CPAP. - See Williams et al. (2011)
Cardiff (II)	- Masks give different values due to breathing exertion and leakage. - Suitable for measuring “true” tidal volume and minute volume. - See Williams et al. (2011)
Bergen	- Important in clinical situations when lung function evaluation would be helpful, but no suitable tools are available. - Potential utility includes evaluations related to Bronchopulmonary Dysplasia, respiratory syncytial virus and asthma monitoring.

Publication abstracts

In reverse chronological order. Additional publications are forthcoming.

Publication in Pediatric Pulmonology - coming soon.

Williams EM, Pickerd N, Eriksen M, Øygarden K, Kotecha S. Estimation of tidal ventilation in preterm and term newborn infants using electromagnetic inductance plethysmography. Physiol Meas. 2011;32(11):1833–1845.

Tidal volume (VT) measurements in newborn infants remain largely a research tool. Tidal ventilation and breathing pattern were measured using a new device, FloRight, which uses electromagnetic inductive plethysmography,and compared simultaneously with pneumotachography in 43 infants either receiving no respiratory support or continuous positive airway pressure (CPAP).Twenty-three infants were receiving CPAP (gestational age 28 ± 2 weeks, mean ± SD) and 20 were breathing spontaneously (gestational age 34 ± 4 weeks). The two methods were in reasonable agreement, with VT (r2 = 0.69) ranging from 5 to 23 ml (4–11 ml kg−1) with a mean difference of 0.4 ml and limit of agreement of −4.7 to + 5.5 ml. For respiratory rate, minute ventilation,peak flow and breathing pattern indices, the mean difference between the two methods ranged between 0.7% and 5.8%. The facemask increased the respiratory rate (P < 0.001) in both groups with the change in VT being more pronounced in the infants receiving no respiratory support. Thus, FloRight provides an easy to use technique to measure term and preterm infants in the clinical environment without altering the infant's breathing pattern.

Walter K, Olden C, Symes E, Seddon P. Discrimination between neonates with and without lung disease using a volumetric vest system. In: Thematic Poster Session : Paediatric and neonatal intensive care. Spain: European Respiratory Society; 2010.

Tidal breathing parameters are a non-invasive surrogate for infant lung function measurement, but usefulness is limited by variability and the need to apply a facemask. Only T PTEF /TE has been widely studied in infants; other parameters have been proposed. We have recently validated a novel volumetric vest system (FloRight) for measuring not only a range of tidal breathing parameters but also thoraco-abdominal asynchrony (TAA). To assess the potential of tidal breathing parameters and TAA to detect lung disease in neonates, we measured both repeatability and ability to discriminate between healthy term newborns (N) and preterm infants with bronchopulmonary dysplasia (BPD). We collected 2 periods of tidal breathing in 10 N and 11 BPD infants during quiet sleep and analysed two 20-breath segments of stable tidal breathing for each baby. The vest system not only allows to distinguish between infants with and without lung disease in several tidal breathing parameters but also detects functional differences such as TAA measured by φ.

Olden C, Symes E, Seddon P. Measuring tidal breathing parameters using a volumetric vest in neonates with and without lung disease. Pediatr. Pulmonol. 2010;45(11):1070–1075.

Lung function measurement is difficult in unsedated infants; tidal breathing parameters are a useful non-invasive surrogate, but even these measurements cause disturbance from applying a facemask. We investigated a novel volumetric vest system (FloRight), which measures volume changes of the respiratory system from changes in the magnetic fields induced by current-carrying coils around the entire chest and abdomen. Using a facemask and ultrasonic flowmeter as comparator, we assessed the validity and repeatability of tidal breathing parameters measured by FloRight in 10 healthy newborn infants during natural sleep. We also assessed the effect of a facemask on tidal volume and tidal expiratory flow parameters. To assess the ability of the FloRight system to detect disease, we compared the healthy infants with 11 infants suffering from bronchopulmonary dysplasia. Tidal parameters with the FloRight vest corresponded closely with facemask measurements. Mean difference, mask minus vest, for tidal volume was 0.096 ml (P < 0.05), with limits of agreement +4.5 to -4.3 ml. Coefficient of repeatability was similar for mask and vest measurements. Tidal volume measured by FloRight with mask in place (20.6 ml) was significantly higher than without mask (16.1 ml), but tidal expiratory flow parameters were not altered. FloRight measurements of tidal parameters were markedly different between the two groups of infants, with tidal volume per Kg significantly higher and tidal expiratory flow parameters significantly lower. Our findings suggest that the FloRight system is able to measure tidal breathing parameters accurately, in healthy newborn infants, without prior calibration on the infant. It appears to have at least sufficient sensitivity to detect severe respiratory disease.

Olden C, Seddon P. Measuring Tidal Breathing Parameters Using a Volumetric Vest in Newborn Infants. In: Thematic Poster Session, Pediatric pulmonary measurement techniques and basic studies. San Francisco, California, US: American Thoracic Society; 2007.

Tidal breathing parameters have been used as non-invasive markers of lung function in infants, but measuring them with minimal disturbance is problematic. Usually airflow is measured via a face mask, but this causes arousal, is poorly tolerated in infants with lung disease, and adds deadspace. Respiratory inductance plethysmography is posture-dependent and requires calibration with face mask measurements if absolute tidal volumes are needed. We assessed a novel device (FloRight, Volusense, Kongsvinger, Norway) which uses a continuous coil in a vest worn over chest and abdomen, carrying a weak alternating current, and an external magnetic field sensor. Changes in volume of the respiratory system are measured by changes in the external magnetic field generated. We aimed to assess whether tidal parameters measured by the Volusense system were equivalent to those measured directly by face mask airflow, and to assess the effect on tidal parameters of having a face mask in place. 10 newborn infants had simultaneous measurements of tidal breathing parameters -tidal volume (VT) and time to peak tidal expiratory flow as a proportion of expiratory time (TPTEF/TE) - a) by measuring flow through a face mask (Msk) and b) by measuring volume changes via vest (Vst). Tidal parameters were also measured by Vst with the mask removed. Mean (SD) VT measured by Vst was 19.8ml (4.7) and by Msk was 19.9ml (5.3) - no significant difference. Mean difference (limits of agreement) was 0.096ml (+4.5 to -4.3). Mean (SD) TPTEF/TE by Vst was 0.51 (0.15); by Msk 0.50 (0.09) - mean difference (limits) -0.01 (+0.32 to -0.35). VT by Vst with mask in place - 20.6 (4.1) was significantly higher than without mask - 16.1 (3.8), but TPTEF/TE did not change significantly. Tidal parameters can be accurately measured using this system without the need for volume calibration. As expected, presence of a facemask increases tidal volume but does not significantly alter TPTEF/TE.