Mathematical analysis of atelectasis formation in middle ears with sealed ventilation tubes

Fink, Nir; Ar, Amos; Sadé, Jacob; Barnea, Ofer

doi:10.1046/j.1365-201x.2003.01096.x

Cited by 24 publications

(22 citation statements)

References 27 publications

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“…This general method has been used in different animals, e.g., rabbits (Hamada et al 2002), rats (Kania et al 2004), and monkeys (Doyle and Seroky 1994;Doyle et al 1995, and also in humans (Aoki et al 1998;Uchimizu et al 2005). It has also been described by mathematical models (e.g., Fink et al 2003).…”

Section: Introductionmentioning

confidence: 97%

“…The assumption that the initial increase in volume (Kania et al 2004;this study) or in pressure (Hamada et al 2002;Aoki et al 1998;Uchimizu et al 2005) can be attributed to an initially relatively fast CO 2 diffusion into the ME space from the blood circulating in the mucosa is based on the fact that its mucosal solubility is much higher than that of the other gases involved (Sadé and Ar 1997;Doyle and Seroky 1994;Fink et al 2003). This assumption was further supported experimentally in rabbits where phase Ba^did not occur when the ME was initially flushed with a gas mixture containing 5% CO 2 (similar to venous blood; Hamada et al 2002).…”

Section: Introductionmentioning

confidence: 97%

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High-Resolution Measurements of Middle Ear Gas Volume Changes in the Rabbit Enables Estimation of its Mucosal CO2 Conductance

Marcusohn

Dirckx

2006

JARO

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Transmucosal CO(2) exchange in the middle ear (ME) of the New Zealand White rabbit (Oryctolagus cuniculus) was studied using an accurate novel detecting and recording system for measuring gas volume changes at constant pressure, based on a principle that was previously used by Kania et al. (Acta Otolaryngol 124:408-410, 2004). After the ME cavity was washed with ambient air, the initial diffusion rate of CO(2) (V(.-)(i)CO(2)) from the blood perfusing the ME mucosa was calculated from gas volume change measurements. In nine cases, the (V(.-)(i)CO(2))calculated after normalization due to shifts in baseline was 314+/-112 microL x h(-1) (mean +/- SD). In two cases where normalization was not needed, (V(.-)(i)CO(2)) was 409 microL x h(-1) (276 and 543 microL x h(-1)). Normalization of (V(.-)(i)CO(2)) data was also made in five additional cases where secretion of fluids from the lining of the ear canal was observed. In these cases (V(.-)(i)CO(2)) was 245 +/- 142 microL x h(-1). No differences were found between results obtained in the three groups. Thus, an overall mean value of (V(.-)(i)CO(2)) of 305 +/- 131 microL x h(-1) (n = 16) was calculated. An effective coefficient of conductance of CO(2) (G(CO(2))) between the mucosal circulation and the ME gas cavity of the New Zealand White rabbit was estimated to be approximately 0.05 microL (h x Pa)(-1) and compared to the G(CO(2)) estimated for humans in a different study.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

High-Resolution Measurements of Middle Ear Gas Volume Changes in the Rabbit Enables Estimation of its Mucosal CO2 Conductance

Marcusohn

Dirckx

2006

JARO

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“…Considering the above ratio and the initial partial pressure differences given in Table 2, the initial rate at which O 2 diffuses into the blood is calculated to be 4.3 times the rate at which N 2 diffuses into the ME. For CO 2 , the solubility times diffusivity product is ϳ35 times higher than that of N 2 (7,8,11,14,15,17). Taking into account the initial gradient, CO 2 is initially transported into the ME cavity at ϳ480 times the N 2 rate.…”

Section: Phase Imentioning

confidence: 99%

“…Hence the experimental results fit the mathematical model for phase II, which suggest a predominant role of N 2 diffusion as a limiting factor in the rate of gas loss we observed. Other experimental studies and mathematical models based on ME pressure changes attribute to the ME to blood partial pressure difference of N 2 the role of dominating the ME gas economy (3,9,10,17,35,39).…”

Section: Phase IImentioning

confidence: 99%

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Role of nitrogen in transmucosal gas exchange rate in the rat middle ear

Kania¹,

Herman²,

Huy³

et al. 2006

Journal of Applied Physiology

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. Role of nitrogen in transmucosal gas exchange rate in the rat middle ear. J Appl Physiol 101: [1281][1282][1283][1284][1285][1286][1287] 2006. First published July 13, 2006; doi:10.1152/japplphysiol.00113.2006.-This study investigates the role of nitrogen (N 2) in transmucosal gas exchange of the middle ear (ME). We used an experimental rat model to measure gas volume variations in the ME cavity at constant pressure. We disturbed the steady-state gas composition with either air or N 2 to measure resulting changes in volume at ambient pressure. Changes in gas volume over time could be characterized by three phases: a primary transient increase with time (phase I), followed by a linear decrease (phase II), and then a gradual decrease (phase III). The mean slope of phase II was Ϫ0.128 l/min (SD 0.023) in the air group (n ϭ 10) and Ϫ0.105 l/min (SD 0.032) in the N 2 group (n ϭ 10), but the difference was not significant (P ϭ 0.13), which suggests that the rate of gas loss can be attributed mainly to the same steady-state partial pressure gradient of N 2 reached in this phase. Furthermore, a mathematical model was developed analyzing the transmucosal N2 exchange in phase II. The model takes gas diffusion into account, predicting that, in the absence of change in mucosal blood flow rate, gas volume in the ME should show a linear decrease with time after steady-state conditions and gas composition are established. In accordance with the experimental results, the mathematical model also suggested that transmucosal gas absorption of the rat ME during steady-state conditions is governed mainly by diffusive N2 exchange between the ME gas and its mucosal blood circulation. rat model

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Middle Ear Pressure Regulation: Physiology and Pathology

Mansour

Magnan

Haidar

et al. 2014

Tympanic Membrane Retraction Pocket

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Mathematical analysis of atelectasis formation in middle ears with sealed ventilation tubes

Abstract: The model demonstrates that under the above conditions, diffusive gas transfer in relation to blood gas content is the leading mechanism to alterations in ME pressure and volume. It may be used as a tool to determine ME physiological cavity volume of ears with VT.

Cited by 24 publications

References 27 publications

High-Resolution Measurements of Middle Ear Gas Volume Changes in the Rabbit Enables Estimation of its Mucosal CO2 Conductance

High-Resolution Measurements of Middle Ear Gas Volume Changes in the Rabbit Enables Estimation of its Mucosal CO2 Conductance

Role of nitrogen in transmucosal gas exchange rate in the rat middle ear

Middle Ear Pressure Regulation: Physiology and Pathology

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