Variability of inspired oxygen concentration with nasal cannulas.

Bazuaye, E A; Stone, T N; Corris, Paul A.; Gibson, G J

doi:10.1136/thx.47.8.609

Cited by 111 publications

(70 citation statements)

References 6 publications

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“…2). The wide scatter on each of these points is similar to that previously found in studies investigating supplemental oxygen supplied to spontaneously ventilating patients via variable performance masks [3] and nasal cannulae [4]. For variable performance masks, the scatter is due to differences in inspiratory flow between patients [3], and the different ventilator settings for each patient in this study is likely to have been the reason for the wide interindividual variation at each flow rate.…”

Section: Discussionsupporting

confidence: 78%

Supplemental oxygen and nasal intermittent positive pressure ventilation

Padkin

Kinnear²

1996

Eur Respir J

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When supplementary oxygen is necessary with nasal intermittent positive pressure ventilation (NIPPV), the optimal route by which it should be added to the ventilator circuit is unknown. We investigated the oxygen concentration received when oxygen was supplied at flow rates between 0 and 6 L·min -1 into the proximal ventilator tubing or the nasal mask whilst patients were ventilated with air.Eleven patients with stable chronic hypercapnic respiratory failure were studied. A calibration curve was produced for each by supplying different known oxygen concentrations through a Monnal D or DCC ventilator and measuring the arterial oxygen saturations achieved. Oxygen was then supplied into the ventilator tubing or nasal mask and arterial saturation again measured. The oxygen concentration received was estimated using the calibration curve. Tracheal oxygen concentration throughout the respiratory cycle was studied in one patient when oxygen was supplied by both routes.Peak inspired oxygen concentration occurred at end-inspiration when oxygen was supplied into the ventilator tubing, but at mid-inspiration when supplied into the nasal mask. However, there was no significant difference between the two routes in the inspired oxygen concentration achieved at all flow rates: 1 L·min -1 supplied approximately 31% oxygen; 2 L·min -1 37%; 3 L·min -1 40%; and 4 L·min -1 44%. Flow rates above 4 L·min -1 had little additional effect.In conclusion, oxygen supplementation during nasal intermittent positive pressure ventilation can be provided into the ventilator tubing or the nasal mask with equal efficiency.

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Section: Discussionsupporting

confidence: 78%

Supplemental oxygen and nasal intermittent positive pressure ventilation

Padkin

Kinnear²

1996

Eur Respir J

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“…12 Using Leigh's technique, Bazuaye et al estimated cannula performance and also measured oxygen response with both normal subjects and patients, using an ear oximeter. 13 That technique found concentrations slightly higher than the cricothyroid catheter data; it also recorded substantial inter-subject variation. At 1 L/min, normal subjects had a mean F IO 2 of 0.267, with a coefficient of variation of 10%.…”

Section: Clinical Evaluation Of Adult Low-flow Nasal Cannulasmentioning

confidence: 99%

“…) nulas during an exacerbation is likely to be appreciably greater than that found here." 13 The aforementioned research makes clear several points: measurement of nasal cannula F IO 2 is not clinically practical; there is performance variability even among normal subjects; textbook predictions are overly optimistic and not based on research data; and delivered F IO 2 decreases considerably during conditions associated with dyspnea. Because of these 4 factors, the noninvasive pulse oximeter has gained nearly universal acceptance to allow titration of oxygen flow to the cannula.…”

Section: Clinical Evaluation Of Adult Low-flow Nasal Cannulasmentioning

confidence: 99%

High-Flow Oxygen Administration by Nasal Cannula for Adult and Perinatal Patients

2012

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The nasal cannula has been a commonly used patient interface to provide supplemental oxygen since its introduction in the 1940s. Traditionally, it has been categorized as a low-flow device and capable of delivering a 0.4 F IO 2 with flows up to 6 L/min to adults with normal minute ventilation. However, there is considerable performance variability among patients and design, which results in an exponential decline in delivered F IO 2 as breathing frequencies increase. The nasal cannula has also been successfully adapted for use in perinatal and pediatric respiratory care; flows are reduced, in the range of 0.25-1 L/min, due to smaller minute volumes. A decade or so ago, high-flow nasal cannula (HFNC) oxygen therapy was introduced, accompanied by heated humidification systems to prevent the associated drying of upper airway mucosa and to increase patient comfort. Therapeutic flows for adults were in the 15-40 L/min range; F IO 2 could be independently adjusted with air/O 2 blending. The HFNC has also found additional clinical application in perinatal care, as delivery systems with flows > 2 L/min could create a distending pressure similar to nasal CPAP. There is a small but growing body of information from clinical trials that supports use of HFNC as an alternative oxygen interface for adults who present with moderate hypoxemia that persists after receiving oxygen by reservoir-bag masks or similar therapy. Clinical observations report greater patient acceptance and comfort versus oxygen masks. HFNC therapy has also been considered valuable in perinatal care in treating the respiratory distress syndrome or supporting patients after extubation similar to nasal CPAP. At present, research-based evidence for the role of HFNC for its perinatal applications remains unclear. This review will identify proposed mechanisms for therapeutic effectiveness, current delivery equipment, guidelines for rational patient application, and direction for further research.

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“…Controlled oxygen can be safely administered via a Venturi-based face mask or through nasal prongs. The inspired oxygen concentration is less precisely controlled when prongs are used [30], but the patient is less likely to remove prongs than a face mask [31]. Either way, nursing care is needed to ensure that treatment is used appropriately and blood gas levels should be monitored after treatment to ensure satisfactory therapy without risk of CO 2 retention.…”

Section: Maintaining Gas Exchangementioning

confidence: 99%

Respiratory failure in chronic obstructive pulmonary disease

Calverley¹

2003

Eur Respir J

107

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Respiratory failure in chronic obstructive pulmonary disease. P.M.A. Calverley. #ERS Journals Ltd 2003. ABSTRACT: Respiratory failure is still an important complication of chronic obstructive pulmonary disease (COPD) and hospitalisation with an acute episode being a poor prognostic marker. However, other comorbid conditions, especially cardiovascular disease, are equally powerful predictors of mortality.The physiological basis of acute respiratory failure in COPD is now clear. Significant ventilation/perfusion mismatching with a relative increase in the physiological dead space leads to hypercapnia and hence acidosis. This is largely the result of a shift to a rapid shallow breathing pattern and a rise in the dead space/tidal volume ratio of each breath. This breathing pattern results from adaptive physiological responses which lessen the risk of respiratory muscle fatigue and minimise breathlessness.Treatment is directed at reducing the mechanical load applied to each breath, correcting specific precipitating factors, e.g. bacterial infection, and maintaining gas exchange. Both bronchodilators and oral corticosteroids can improve spirometric results in exacerbations of COPD and should be routinely offered to patients with respiratory failure. Controlled oxygen is still not always prescribed appropriately and high inspired oxygen concentrations can lead to severe acidosis by either worsening ventilation/perfusion mismatching and/or inducing a degree of hypoventilation. Ventilatory support using noninvasive ventilation has revolutionised the approach to these patients.Acute respiratory failure due to chronic obstructive pulmonary disease remains a common medical emergency that can be effectively managed. More attention should be focused on the prevention of these episodes and identifying the factors which cause early relapse. Eur Respir J 2003; 22: Suppl. 47, 26s-30s.

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Variability of inspired oxygen concentration with nasal cannulas.

Cited by 111 publications

References 6 publications

Supplemental oxygen and nasal intermittent positive pressure ventilation

Supplemental oxygen and nasal intermittent positive pressure ventilation

High-Flow Oxygen Administration by Nasal Cannula for Adult and Perinatal Patients

Respiratory failure in chronic obstructive pulmonary disease

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