Effects of oxygen insufflation rate, respiratory rate, and tidal volume on fraction of inspired oxygen in cadaveric canine heads attached to a lung model

Zimmerman, Melina E; Hodgson, David A.; Bello, Nora M.

doi:10.2460/ajvr.74.9.1247

Cited by 8 publications

(3 citation statements)

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“…However, as reported by several studies, the F DO 2 varies according to the O 2 flow and/or the patient's respiratory pattern (eg, frequency, tidal volume). 1,2,3 This raises the question about F DO 2 prediction in patients who are intubated or tracheotomized oxygenated patients who breathe spontaneously with a Heat Moisture Exchanger (HME). In recent years, F DO 2 -validated formulas have been promoted.…”

Section: Introductionmentioning

confidence: 99%

A New Formula for Predicting the Fraction of Delivered Oxygen During Low-Flow Oxygen Therapy

et al. 2018

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BACKGROUND: During O 2 therapy at low flow in patients who breathe spontaneously, the fraction of delivered O 2 (F DO 2 ) is unknown. In recent years, F DO 2 prediction formulas have been proposed. However, they do not take into account the effect of inspiratory flow (V I ) on the F DO 2 . The aim of this study was to validate a new F DO 2 prediction formula, which takes into account the V I and compares it with other F DO 2 prediction formulas. METHODS: During a bench study, spontaneous breathing was generated with a mechanical test lung connected to a mechanical ventilator set to volume control mode. O 2 flow from a wall-mounted tube was delivered through a heat-and-moisture exchanger filter. A flow sensor recorded each breath of the V I in ambient temperature and barometric pressure conditions. Three parameters [O 2 flow at 2, 3, 4, 5, 6 L/min; minute ventilation at 5, 10, 15, 20 L/min; and ratio of the inspiratory time (T I ) to the total breathing cycle time (T tot ) (T I /T tot ) of 0.33 (T I /T tot value) and 0.50 (T I /T tot value)] were modified to generate many ventilatory patterns. An O 2 analyzer continuously examined the F DO 2 . RESULTS: When the O 2 flow and/or T I /T tot increased, the F DO 2 increased. When the minute ventilation increased, the F DO 2 decreased. The results of the Bland-Altman method for the F DO 2 , calculated by using our mathematical model and the measured F DO 2 , showed that the mean ؎ SD bias value was equal to 1.49 ؎ 0.84%, and the limits of agreement ranged from ؊0.17% to 3.14%. The intraclass correlation coefficients were 0.991 for T I /T tot ‫؍‬ 0.33 and 0.994 for T I /T tot ‫؍‬ 0.50, and the coefficient of variation was 2.1% for T I /T tot ‫؍‬ 0.33 and 1.3% for T I /T tot ‫؍‬ 0.50. The results of the Bland-Altman method for the F DO 2 calculated by using the Shapiro formula and the F DO 2 measured on the bench indicated that the bias value was 0.075 ؎ 8.66% and the limits of agreement ranged from ؊16.89% to 17.04%. For the Vincent formula, the bias value was 3.08% ؎ 8.56% and the limits of agreement ranged from ؊13.69% to 19.84%. CONCLUSIONS: The V I has a major impact on F DO 2 during O 2 therapy at low flow. F DO 2 comparisons between frequently used prediction formulas and F DO 2 measured on the bench indicated greater differences. Uncritical use of these formulas should be used cautiously to predict F DO 2 . In this study, our prediction formula indicated a good accuracy for predicting F DO 2 during supplemental oxygenation through a heat-and-moisture exchanger in patients who breathe spontaneously.

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Section: Introductionmentioning

confidence: 99%

A New Formula for Predicting the Fraction of Delivered Oxygen During Low-Flow Oxygen Therapy

et al. 2018

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“…Using a higher nasal insufflation rate would allow a better flush of the anatomical dead space, increasing the available oxygen concentration and volume for inhalation, and would better match the inspiratory flow of bison, leading to an increased fraction of inspired oxygen, although higher flow rates can exacerbate hypercapnia ( 65–67 ). The respiratory rate, the breathing pattern, and the delivery method also contribute to the efficiency of oxygen supplementation ( 47 , 67 , 68 ). Yet, we strongly recommend investigating higher delivery rates while balancing hypercapnia for relieving hypoxemia in immobilized European bison.…”

Section: Discussionmentioning

confidence: 99%

Arterial oxygenation and acid–base status before and during oxygen supplementation in captive European bison (Bison bonasus) immobilized with etorphine-acepromazine-xylazine

Gardoni,

Björck,

Morelli

et al. 2023

Front. Vet. Sci.

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Chemical immobilization of captive European bison (Bison bonasus) is often required for veterinary care, transportation, or husbandry practices playing an important role in conservation breeding and reintroduction of the species. We evaluated the efficiency and physiological effects of an etorphine-acepromazine-xylazine combination with supplemental oxygen in 39 captive European bison. Animals were darted with a combination of 1.4 mg of etorphine, 4.5 mg of acepromazine, and 20 mg of xylazine per 100 kg based on estimated body mass. Arterial blood was sampled on average 20 min after recumbency and again 19 min later and analyzed immediately with a portable i-STAT analyzer. Simultaneously, heart rate, respiratory rate, and rectal temperature were recorded. Intranasal oxygen was started after the first sampling at a flow rate of 10 mL.kg−1.min−1 of estimated body mass until the end of the procedure. The initial mean partial pressure of oxygen (PaO2) was 49.7 mmHg with 32 out of 35 sampled bison presenting with hypoxemia. We observed decreased respiratory rates and pH and mild hypercapnia consistent with a mild respiratory acidosis. After oxygen supplementation hypoxemia was resolved in 21 out of 32 bison, but respiratory acidosis was accentuated. Bison immobilized with a lower initial drug dose required supplementary injections during the procedure. We observed that lower mean rectal temperatures during the immobilization event were significantly associated with longer recovery times. For three bison, minor regurgitation was documented. No mortality or morbidity related to the immobilizations were reported for at least 2 months following the procedure. Based on our findings, we recommend a dose of 0.015 mg.kg−1 etorphine, 0.049 mg.kg−1 acepromazine, and 0.22 mg.kg−1 xylazine. This dose reduced the need for supplemental injections to obtain a sufficient level of immobilization for routine management and husbandry procedures in captive European bison. Nevertheless, this drug combination is associated with development of marked hypoxemia, mild respiratory acidosis, and a small risk of regurgitation. Oxygen supplementation is strongly recommended when using this protocol.

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“…Lastly, the effect of tidal volume was not considered in this study and may have limited the rise in the FiO 2 measured. Dexmedetomidine increases the tidal volume that is negatively associated with the FiO 2 , achieved by maintaining a constant oxygen insufflation rate [24,25].…”

Section: Discussionmentioning

confidence: 99%

Oxygen Reserve Index as a Tool to Monitor Four Techniques of Oxygen Supplementation at Different Flow Rates in Dogs Sedated with Dexmedetomidine and an Opioid

Bellini,

De Benedictis

2023

Animals

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Respiratory dysfunction often decreases arterial oxygen content. Four common oxygen delivery techniques—flow-by, nasal prongs, a tight-vented mask, and a tight mask connected to a Venturi valve—were evaluated for their effectiveness in increasing the oxygen reserve index (ORi), a dimensionless index of oxygen content that provides additional information compared to traditional pulse oximetry (SpO2) during hyperoxia (PaO2 100–200 mmHg), and that ranges from 0 to 1. Thirty-two dogs sedated with dexmedetomidine and an opioid were evenly divided into four groups based on the technique for oxygen administration. Each dog received oxygen at 1, 2, and 3 L/min by a single technique, and the amount of inhaled oxygen (FiO2) was measured at the level of the cervical trachea. At each flow rate, ORi and SpO2 were recorded. The flow-by method minimally increased the FiO2, and ORi reached its highest value only in 3 out of 8 dogs at the maximum flow rate. Other methods exhibited direct correlations between the oxygen flow rate and ORi (p < 0.001). These methods effectively increased FiO2 and ORi, with over half of the values exceeding 40% and 0.4, respectively. The tight-vented mask showed variable increases in FiO2, ranging between 22 and 90%. Despite method-dependent variations, all devices increased SpO2 > 98% as the FiO2 increased (p = 0.002). In conclusion, nasal prongs and the mask connected to the Venturi valve showed the highest correlation between the oxygen flow rate and the ORi. These results suggest that using these two techniques in conjunction with ORI can help in optimizing oxygen therapy.

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Effects of oxygen insufflation rate, respiratory rate, and tidal volume on fraction of inspired oxygen in cadaveric canine heads attached to a lung model

Abstract: -Fio2 in the model was affected by oxygen insufflation rate, respiratory rate, and tidal volume. This information may potentially help clinicians interpret results of blood gas analysis and manage canine patients receiving oxygen insufflation via a nasal catheter.

Cited by 8 publications

References 4 publications

A New Formula for Predicting the Fraction of Delivered Oxygen During Low-Flow Oxygen Therapy

A New Formula for Predicting the Fraction of Delivered Oxygen During Low-Flow Oxygen Therapy

Arterial oxygenation and acid–base status before and during oxygen supplementation in captive European bison (Bison bonasus) immobilized with etorphine-acepromazine-xylazine

Oxygen Reserve Index as a Tool to Monitor Four Techniques of Oxygen Supplementation at Different Flow Rates in Dogs Sedated with Dexmedetomidine and an Opioid

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