Advertisement

Accuracy of oxygen delivery through bubble humidifiers and nasal catheters

Published:February 08, 2020DOI:https://doi.org/10.1016/j.vaa.2020.01.004

      Abstract

      Objective

      To evaluate the equipment used for nasal insufflation of oxygen and determine its accuracy.

      Study design

      Original study.

      Methods

      Oxygen delivery assemblies consisting of a flowmeter, bubble humidifier, oxygen delivery tubing and nasal insufflation catheters were assembled. Single and double catheter assemblies were made for four sizes of nasogastric feeding tubes (3.5 Fr, 5.0 Fr, 8.0 Fr and 10.0 Fr) resulting in 64 individual assemblies. A gas flow analyzer measured oxygen flow at the tip of the nasal catheter assemblies and from the pressure relief valve (PRV) of the bubble humidifiers. Statistical analyses were conducted to assess the functionality of assemblies. For functional assemblies, the accuracy of oxygen flow relative to the prescribed flow settings was determined.

      Results

      Catheter size was significantly associated with the functionality of assemblies. Probability (95% confidence interval) of 3.5 Fr, 5.0 Fr and 8.0 Fr assemblies being functional was estimated at 0.53 (0.14, 0.89), 0.83 (0.36, 0.98) and 0.98 (0.76, 0.99), respectively. All 10.0 Fr assemblies were functional. Functional assemblies, in general, consistently under-delivered the prescribed flow because a large portion of set flow was diverted through the bubble humidifier PRV.

      Conclusions

      Leaks through the PRV cause significant diversion of oxygen prior to it reaching the catheter tips. Smaller patients are particularly susceptible, as small catheters limit oxygen delivery creating proportionally greater leaks through the PRV.

      Clinical relevance

      It was not possible to accurately deliver oxygen because of leaks through the PRV. Targeting a specific outcome (e.g., oxyhemoglobin saturation > 94%, PaO2 80–120 mmHg; 11–16 kPa) and avoiding unnecessarily high fractions of inspired oxygen cannot be done if flow delivery cannot be accurately assured. One possible solution would be to use a bubble humidifier with a 6 psi PRV that does not leak prior to reaching the opening pressure.

      Keywords

      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'

      Subscribe:

      Subscribe to Veterinary Anaesthesia and Analgesia
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect

      References

        • Boyle J.
        Oxygen therapy.
        in: Burkitt Creedon J.M. Davis H. Advanced Monitoring and Procedures for Small Animal Emergency and Critical Care. John Wiley & Sons Inc., UK2012: 263-273
        • Camps-Palau M.A.
        • Marks S.L.
        • Cornick J.L.
        Small animal oxygen therapy.
        Comp Cont Educ. 1999; 21: 587-598
        • Compressed Gas Association Inc.
        CGA E-7-2013 Medical Gas Pressure Regulators, Flowmeters, and Orifice Flow Selectors.
        4th edn. CGA, USA2013
        • Drobatz K.J.
        • Hackner S.
        • Powell S.
        Oxygen supplementation.
        in: Bonagura J.D. Kirk R.W. Kirk’s Current Veterinary Therapy Small Animal Practice. 12th edn. W.B. Saunders Co., USA1995: 175-179
        • Dunphy E.D.
        • Mann F.A.
        • Dodam J.R.
        Comparison of unilateral versus bilateral nasal catheters for oxygen administration in dogs.
        J Vet Emerg Crit Care. 2002; 12: 245-251
        • Fitzpatrick R.K.
        • Crowe Jr, D.T.
        Nasal oxygen administration in dogs and cats: experimental and clinical investigations.
        J Am Anim Hosp Assoc. 1986; 22: 293-300
        • Murphy M.L.
        • Hodgson D.S.
        • Bello N.M.
        On accuracy and precision of flowmeters used for oxygen therapy in a veterinary teaching hospital.
        Vet Anaesth Analg. 2018; 45: 41-47
        • Tseng L.W.
        • Drobatz K.J.
        Oxygen supplementation and humidification.
        in: King L.G. Textbook of Respiratory Disease in Dogs and Cats. Saunders, USA2004: 205-213