Advice
Clinical and technical evidence
Clinical and technical evidence
A literature search was carried out for this briefing in accordance with the interim process and methods statement. This briefing includes the most relevant or best available published evidence relating to the clinical effectiveness of the technology. Further information about how the evidence for this briefing was selected is available on request by contacting mibs@nice.org.uk.
Published evidence
There are 3 studies summarised in this briefing; other technical evidence was excluded because the studies used mannequins rather than people.
There is 1 retrospective before-and-after evaluation of safety and cost, 1 unblinded crossover trial and 1 pilot-randomised, single-blind crossover trial. All studies were done in the US or Canada.
The retrospective study does not report how many people's data were reviewed, but based on the reported number of oxygen masks it is estimated at more than 9,000. The other studies included 36 adults, 10 of which were healthy volunteers.
Table 1 summarises the clinical evidence as well as its strengths and limitations.
Overall assessment of the evidence
The evidence for the effectiveness of OxyMask for delivering oxygen therapy is limited in quality and quantity. None of the studies reported their methods and results in detail. The variety of outcomes reported across all studies make it difficult to draw conclusions from the evidence.
All of the studies were done in the US or Canada so the results may not be generalisable to the NHS. The protocols for delivering oxygen therapy may differ to those used in the NHS but the company have confirmed that the devices are the same and have the same flow restrictions and capabilities as those available in the UK.
Table 1 Summary of selected studies
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Study size, design and location |
A retrospective before-and-after evaluation of the safety and cost of oxygen therapy from data collected at a 395-bed acute care hospital in the US over a 2-year period. |
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Intervention and comparator(s) |
Intervention: OxyMask. Comparator: traditional oxygen mask devices including simple oxygen masks, adult 3-in-1 oxygen masks, partial rebreathing masks, non-rebreathing masks, tracheostomy masks, nasal cannulae. |
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Key outcomes |
There were fewer 'unusual occurrence' reports after the introduction of OxyMask (after: 0 versus before: 4). |
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Strengths and limitations |
It is not reported how many people were included, but based on the reported number of oxygen masks used it is estimated to be over 9,000 (around 3,800 for traditional oxygen masks and around 5,500 for OxyMask). It is not defined what is meant by an 'unusual occurrence'. 2 clinical areas continued to use traditional oxygen delivery devices up to 5 months after the introduction of OxyMask. It is not reported how many patients this would have affected but it means that this is not a simple before-and-after study. |
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Study size, design and location |
An unblinded crossover trial in 10 healthy adults in Canada. |
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Intervention and comparator(s) |
Intervention: OxyMask. Comparator: venturi mask. |
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Key outcomes |
The oxygen flow rate needed to maintain a high saturation was claimed to be significantly lower in OxyMask compared with the venturi mask (2.1 versus 12.2 litres/min) and the PiO2 at the lip was claimed to be significantly higher (323 versus 257 mmHg). |
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Strengths and limitations |
Only 10 adults were recruited into the study. The methods section gives details of how the OxyMask was delivered but there are no details for the venturi mask. This study is at high risk of reporting bias. The study received funding from the company that makes OxyMask. There is no p value reported to support the claims of significance. |
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Study size, design and location |
A pilot-randomised, single-blind, crossover trial of 26 adults with chronic pulmonary disease who were using supplemental oxygen in Canada. |
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Intervention and comparator(s) |
Intervention: original OxyMask (trialled by 13 adults) and modified OxyMask (trialled by 13 adults). Comparator: venturi mask (Hudson RCI). |
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Key outcomes |
Oxygen flow rate was significantly lower when using OxyMask compared with the venturi mask (at low saturation 1.8 versus 5.2 litres/min; at high saturation 4.4 versus 10.8 litres/min; p<0.001). Inspired PO2 was significantly higher (at low saturation 217.3 versus 189.4 mmHg; at high saturation 323.5 versus 257.4 mmHg, p<0.001) and expired PO2 was significantly lower (at low saturation 162.6 versus 182.1; at high saturation 216.7 versus 245.5, p<0.001). There was no significant difference in minute ventilation and expired PCO2. Ratings of mask comfort tended to be higher for OxyMask (6.7 versus 4.9) but the difference was not significant (p=0.09). |
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Strengths and limitations |
Only 13 adults trialled the modified OxyMask. This is a small sample size. The results reported for the original OxyMask are not relevant as that mask design is different to the current mask design and is no longer in use. The methods of randomisation are not reported so the study is at risk of selection bias. The authors hypothesise that OxyMask delivers oxygen more efficiently and more comfortably than the venturi mask but they do not state how these outcomes will be measured and assessed. Two authors of the paper have received financial support from the company that makes OxyMask: 1 to perform the study and the other to present data from the study at an international scientific meeting. |
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Abbreviations: EtCO2, end tidal carbon dioxide; FiO2, fraction of inspired oxygen; NRBM, non-rebreather mask; PCO2, partial pressure of carbon dioxide; PiO2, partial pressure of inspired oxygen; PO2, partial pressure of oxygen; VE, minute ventilation. |
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