An On-Demand Oxygen Flow Meter for Enhanced Patient Comfort and Reduced Oxygen Cost in Hospitals

Figures & data

Figure 1. The O2COMFORT Flowmeter, Oxypoint, Belgium.

Table 1. Patient population.

Diagnosis	No. of patients
Pneumonia	27
Exacerbation of COPD	20
Infection	10
Pulmonary edema	9
Chronic respiratory failure	7
Septicemia	6
Neoplasm	5
Cystic Fibrosis	3
Pneumothorax	3
Asthma exacerbation	3
Pleural effusion	2
Neutropenic Fever	2
Others	35
Total	132

Figure 2. Oxygen delivery in L/min based on the logged flow data of oxygen delivery to the respiratory ward in 132 patients treated with oxygen over a period of 12 weeks. Each data point represents a flow obtained over a 2 min time interval. Black indicates hybrid, gray indicates conventional flow meter periods. The horizontal lines represent the average O₂ utilization in the respective periods.

Table 2. Averaged oxygen consumption (L/min) of the ward measured by the datalogger and manually registered oxygen flow during each 6 consecutive periods.

	Conventional flow meter = only continuous flow		Hybrid flow meter = mixed continuous and on-demand flows
Period	Data- logger	Manually registered	Data- logger	Manually registered
Hybrid period I			7.63	14.62
Conventional period II	21.19	18.49
Hybrid period III			11.76	12.80
Conventional period IV	26.87	22.44
Hybrid period V			14.37	13.57
Conventional period VI	23.05	19.02
Total averaged (L/min)	23.70	19.98	11.26	13.66

Figure 3. Mean oxygen delivery in L/min during the conventional (dark gray), the hybrid (light gray) flow meter periods and after normalization for occupancy, O₂ prescription and administration, and aerosolization. The oxygen sparing effect by 54% based on the mass flow meter logged data is reduced to 39% after normalization.

Table 3. Total and adjusted oxygen consumption (L/min) of the ward averaged over the 6 weeks period measured by the datalogger during the conventional and the hybrid weeks. Corrections for the hybrid weeks were made for bed occupancy, oxygen administration, and oxygen utilization in aerosol therapy.

	Total O2 flow of the ward (L/min) (Conventional weeks = only continuous flows)	Total O2 flow of the ward (L/min) (Hybrid weeks = mixed continuous and on-demand flows)	Normalized Total O2 flow of the ward (L/min) (hybrid weeks = mixed continuous and on-demand flows)
Avg. utilization incl. aerosolization	23,70	11,26	14,38
Avg. utilization excl. aerosolization	22,22	10,24	13,48

Figure 4. Comparison between the relative humidity using continuous flow rates from 1 to 4 liters per minute and their equivalent on-demand flow settings 1 to 4. O = outlier 3^rd quartile + 1.5 * interquartile range or 1^st quartile -1.5 * interquartile range.

Figure 5. Comparison between the saturation levels using continuous flow rates from 1 to 4 liters per minute and their equivalent on-demand flow settings 1 to 4. O = outlier 3^rd quartile +/- 1.5 * interquartile range or 1^st quartile -1.5 * interquartile range; * = outlier 3^rd quartile + 3 * interquartile range or 1^st quartile - 3 * interquartile range.

Table 4. Summary of average relative humidity (RH) between on-demand mode and continuous flow.

Flow rate in l/min	Average RH on demand	Average RH continuous flow	Number of patients	% Decrease of RH	P Value
1	82,27	76,46	7	7%	0,112
2	78,22	73,13	21	7%	0,023
3	74,09	63,97	11	14%	0,001
4	77,07	58,48	7	24%	0,000

Table 5. Average saturation level between on-demand mode and continuous flow for different flow rates.

Flow rate level in l/min	Average saturation level on demand in %	Average saturation level continuous flow in %	P Value
1	94,00	94,00	0,340
2	94,00	95,00	0,000
3	94,00	95,50	0,028
4	92,33	93,50	0,042

Table 6. Summary of average scores of the modified Wong-Baker pain scale for the on-demand mode and continuous flow. A low average score indicates more comfortable therapy. For further details: see text.

Flow rate in l/min	Average score on demand	Average score continuous flow
1	0,3	1,5
2	1,6	2,5
3	1,5	2,4
4	1,6	3,5