Mathematical model to predict inspired oxygen concentration: Description and validation

Wexler, H. R.; Levy, Hart; Cooper, Joel D.; Aberman, Arnold

doi:10.1007/bf03004855

Cited by 6 publications

(3 citation statements)

References 3 publications

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“…When oxygen is administered via LFNC, the FiO 2 delivered to the lungs depends on the supplied oxygen concentration, cannula flow, and pattern of respiration [2][3][4]. The latter is expressed by the respiratory parameters VT, Ti, and Te, the combination of which further determines the RR (RR = 60/[Ti + Te]) and MV [MV = VT × RR].…”

Section: Discussionmentioning

confidence: 99%

“…Oxygen administration to small infants via low-flow nasal cannula (LFNC; gas flow ≤ 2 L/min) is a standard practice in neonatal and pediatric care [1]. However, the fraction of inspired oxygen (FiO 2 ) delivered to the lungs, known as the effective FiO 2 , is difficult to estimate because it depends on many factors: the oxygen concentration in the supplied gas, the cannula flow, and the dynamics of respiration (tidal volume-VT, inspiratory time-Ti, expiratory time-Te) [2][3][4]. Indeed, it has been shown that the hypopharyngeal FiO 2 -a surrogate of the effective FiO 2 -may be extremely variable in small infants receiving oxygen via LFNC [5], even at very low cannula flows (e.g., FiO 2 23-54% at 0.1 L/min 100% oxygen flow) [6].…”

Section: Introductionmentioning

confidence: 99%

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Optimizing Oxygen Delivery by Low-Flow Nasal Cannula to Small Infants: A Bench Study

Bertzouanis,

Sinopidis,

Pelekouda

et al. 2024

Diagnostics

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Background: In infants treated with a low-flow nasal cannula (LFNC), the oxygen concentration delivered to the lungs (i.e., the effective FiO2) is difficult to estimate. The existing mathematical formulas rely on important assumptions regarding the values of respiratory parameters and, thus, may be inaccurate. We aimed to assess oxygen delivery by LFNC to small infants using realistic simulations on a mechanical breathing model. Methods: A mechanical breathing simulator (infant upper-airway replica, single-space breathing compartment, electric motor, microcontroller) was developed. Breathing simulations (n = 1200) were performed at various tidal volume (VT), inspiratory time (Ti), and respiratory rate (RR) combinations and different cannula flows. Results: Minute ventilation (MV) was the most significant predictor of effective FiO2. FiO2 was higher at lower VT and higher Ti values. Benaron and Benitz’s formula underestimated the effective FiO2 at lower MV values, while Finer’s formula significantly overestimated it. A set of predictive FiO2 charts was developed based on cannula flow, infant body weight, and RR. Conclusions: The effective FiO2 delivered by LFNC to small infants critically depends on VT, Ti, and RR. However, since VT and Ti values are not available in clinical practice, the existing mathematical formulas may be inaccurate. Our novel predictive FiO2 charts could assist in optimizing oxygen delivery by LFNC using easy-to-obtain parameters, such as infant body weight and RR.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimizing Oxygen Delivery by Low-Flow Nasal Cannula to Small Infants: A Bench Study

Bertzouanis,

Sinopidis,

Pelekouda

et al. 2024

Diagnostics

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“…(1). 15 The normal concentration of oxygen in room air (21%) was also multiplied by the effective volume of air. Tidal volume was obtained by summing the effective volume of air, effective volume of oxygen, and dead space (Eq.…”

Section: Methodsmentioning

confidence: 99%

The effectiveness of oxygen conserving device of a demand oxygen delivery system based on FIO2 equivalency

Hwan

Kim

Shin

et al. 2011

Int. J. Precis. Eng. Manuf.

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Recently demand oxygen delivery (DOD) system has been preferred to continuous flow oxygen (CFO) method for long term oxygen therapy in patients with chronic obstructive pulmonary disease, since DOD system supplies oxygen during only inhalation and saves oxygen consumption. However, the oxygen saving ratio have not properly compared without considering fraction of inspired oxygen (FIO 2 ), though FIO 2 determines the efficacy of treatment. The purpose of this study was 1) to investigate the equivalence between the CFO method and a DOD system in terms of FIO 2 with considering dead space under various breathing parameters, 2) to propose and calculate the new effective oxygen saving ratio of the DOD method, 3) to compare FIO 2 obtained from calculation with that from experiment. The mathematical and experimental models of human respiratory system were developed. FIO 2 was calculated depending upon various breathing parameters and the new effective oxygen saving ratio was calculated to accurately compare oxygen saving consumption between the DOD and CFO method. Results of this study have shown that as supplied volume of oxygen increased, FIO 2 linearly increased. As beat per minute or tidal volume increased, FIO 2 decreased. The obtained FIO 2 between mathematical model and experiment showed errors less than 5% in CFO method and less than 11% in DOD method. Effective conserving oxygen ratios of the DOD system changed between 3.4 and 3.8, but had higher values when the volume of supplied oxygen was larger. In conclusion, CFO method had different equivalent values of FIO 2 depending on breathing parameters. Therefore it is appropriate to take into account of FIO 2 when considering performance of oxygen saving devices. The effective oxygen saving ratio proposed in this study may provide the new valuable index of oxygen saving of the DOD method while maintaining the same treatment effect compared with CFO method. In addition, the mathematical model developed in this study seems to predict FIO 2 similarly as obtained using experiment.

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Low flow oxygen delivery via nasal cannula to neonates

1996

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Neonates with chronic lung disease often require oxygen in the neonatal intensive care unit. The purpose of this study was to determine (1) the actual inspired oxygen concentration (F1O2) delivered to neonates when using a low‐flow flowmeter and a nasal cannula, and (2) the accuracy with which F1O2 could be estimated using a formula that we developed. We studied two groups of infants: 18 infants less than 1,500 g and 13 infants greater than 1,500 g. We measured pharyngeal oxygen levels by sampling pharyngeal gas in infants receiving 100% humidified oxygen by nasal cannula from a low range flow flowmeter. The oxygen flow was increased by 25 mL/min increments from 25 to 200 mL/min. The measured F1O2 was compared with the calculated F1O2 using the formula: F1O2 measured = oxygen flow (mL/min × 0.79) + (0.21 × VE)/VE× 100, Where minute ventilation (VE) equals the minute ventilation in mL/min (VE = VT × respiratory rate). For both groups of infants, increments of 25 mL/min of flow produced distinctive changes in F1O2 at all levels (P < 0.001). The calculated F1O2 did not significantly differ from the actual F1O2 at any flow. The calculated F1O2 was most predictive when using an assumed tidal volume of 5.5 mL/kg. We conclude that an accurate flowmeter connected to 100% humidified oxygen can produce a wide range of predictable F1O2s for neonates, especially those with birthweights of less than 1,500 g. The proposed formula allows useful estimation of the infant's F1O2 when we assume a tidal volume of 5.5 mL/kg. Pediatr Pulmonol. 1996; 21:48–51. © 1996 Wiley‐Liss, Inc.

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Mathematical model to predict inspired oxygen concentration: Description and validation

Cited by 6 publications

References 3 publications

Optimizing Oxygen Delivery by Low-Flow Nasal Cannula to Small Infants: A Bench Study

Optimizing Oxygen Delivery by Low-Flow Nasal Cannula to Small Infants: A Bench Study

The effectiveness of oxygen conserving device of a demand oxygen delivery system based on FIO2 equivalency

Low flow oxygen delivery via nasal cannula to neonates

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