Does Gastric Juice pH Influence Tonometric P<scp>co</scp> <sub>2</sub>  Measured by Automated Air Tonometry?

Brinkmann, Alexander; Glasbrenner, Bernhard; Vlatten, Arnim; Eberhardt, Holger; Geldner, Götz; Radermacher, Peter; Georgieff, Michael; Wiedeck, Heide

doi:10.1164/ajrccm.163.5.2004057

Cited by 19 publications

(9 citation statements)

References 13 publications

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“…Concentrations of aqueous carbon dioxide and bicarbonate are directly related in the luminal fluid of the GI tract . In the stomach of healthy humans, the percent CO 2 typically ranges between 4% and 10% CO 2 (30–76 mmHg) and similar values are observed in the proximal jejunum . McGeese and Hastings measured an average of 13.2% (100 mmHg) CO 2 in the jejunum at an average pH of 6.5 .…”

Section: Introductionmentioning

confidence: 92%

In Viv o Predictive Dissolution: Transport Analysis of the CO 2 , Bicarbonate In Vivo Buffer System

Krieg

Taghavi

Amidon

et al. 2014

Journal of Pharmaceutical Sciences

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Development of an oral in vivo predictive dissolution medium for acid drugs with a pKa in the physiological range (e.g., Biopharmaceutics Classification System Class IIa) requires transport analysis of the complex in vivo CO2 /bicarbonate buffering system. In this report, we analyze this buffer system using hydrodynamically defined rotating disk dissolution. Transport analysis of drug flux was predicted using the film model approach of Mooney et al based on equilibrium assumptions as well as accounting for the slow hydration reaction, CO2 + H2 O → H2 CO3 . The accuracy of the models was compared with experimentally determined results using the rotating disk dissolution of ibuprofen, indomethacin, and ketoprofen. The equilibrium and slow hydration reaction rate models predict significantly different dissolution rates. The experimental results are more accurately predicted by accounting for the slow hydration reaction under a variety of pH and hydrodynamic conditions. Although the complex bicarbonate buffering system requires further consideration given its dynamic nature in vivo, a simplifying irreversible reaction (IRR) transport analysis accurately predicts in vitro rotating disk dissolution rates of several carboxylic acid drugs. This IRR transport model provides further insight into bicarbonate buffer and can be useful in developing more physiologically relevant buffer systems for dissolution testing.

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Section: Introductionmentioning

confidence: 92%

In Viv o Predictive Dissolution: Transport Analysis of the CO 2 , Bicarbonate In Vivo Buffer System

Krieg

Taghavi

Amidon

et al. 2014

Journal of Pharmaceutical Sciences

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“…Each patient was given the proton pump-inhibitor omeprazol (80 mg day -1 i.v.) to increase gastric juice pH to a value of greater than 4, which improves the accuracy of PiCO 2 measurement [16].…”

Section: Study Procedures Measurements and Calculationsmentioning

confidence: 99%

Effect of prone position on hepato-splanchnic hemodynamics in acute lung injury

Matějovič

Rokyta

Radermacher³

et al. 2002

Intensive Care Med

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P2Model-based neuro-fuzzy control of FiO 2 for intensive care mechanical ventilation HF Kwok, GH Mills, M Mahfouf, DA Linkens Introduction: In our experience, very often, even with a nonrebreathing mask (NRM), high oxygen delivery to patient with the existent materials is insufficient. However, many of these patients need high oxygen therapy for a limited period of time. In this study we report our experience with a new device that serves to increase the concentration of oxygen delivered by a classical nasal cannula or catheter. It is not an oxygen mask. Aim:To demonstrate how a simple adjunctive system to classical nasal cannula or catheter improves considerably the oxygenation of patients at constant O 2 flow rate.Design: Prospective, observational study. Method:The double trunk mask (DTM) is a modified tusk mask described by Hnatiuk. It is composed by a normal aerosol mask with 22 mm of diameter lateral holes, 38 cm of long flexible tubing are inserted to each side of the mask. The DTM is just applied to the face of the patients who already receive O 2 through a nasal cannula or catheter. Forty-five consecutive patients, admitted in the ER or ICU, and needing oxygen delivery, are included in our study. The data collected are: PaO 2 , PaCO 2 , breathing rate with a mean flow rate of 3.58 l/min, at t0, t30 min prior to DTM and then 30 min after DTM application. Results:Nasal The knowledge-based approach to fuzzy logic control of mechanical ventilation on the ICU can be prone to bias in the experts' knowledge and errors resulting from poor communication during rule-base derivation. Therefore, a different approach was explored in the development of a fuzzy controller to control the inspired oxygen fraction (FiO 2 ). The performance of such a controller was compared with the performance of the clinicians.Method: (1) The development of a neuro-fuzzy controller. This was developed by training a neural network to generate an optimal change in the FiO 2 in order to achieve a target arterial oxygen tension (PaO 2 ) on a mathematical model of the gas exchange system (SOPAVent). The neural network learnt the relationship between the blood gases, FiO 2 and PEEP and other ventilator settings. This was done by exposing the neural network to the blood gas results produced by applying a range of FiO 2 and PEEP values to the SOPAVent model. This first neural network was then combined with another neural network which represented a fuzzy logic rule-base. The fuzzy rule-base consists of a set of 'If …, Then …' statements based around combinations of FiO 2 , PEEP and PaO 2 . The fuzzy rule-base was then adjusted by changing the weights of the neuro-controller (which correspond to the 'Then …' part of the fuzzy rules) during neural network training. The neuro-controller output is equivalent to the output from a fuzzy inference system of three inputs (the difference between the actual PaO 2 and the target, the PEEP level and the FiO 2 ).(2) Comparing neuro-fuzzy and clinicians' control. The scenarios were based on the data from th...

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“…Gastric acid suppression can also alter gastric tonometric measurements, and recommendations regarding the need for acid suppression for accurate tonometric measurements vary. In 1 study, gastric PCO 2 increased in response to pentagastrin, which increases acid output, and decreased in response to omeprazole administration, which decreases acid output 9 . Because ill foals are commonly treated with acid‐suppressing agents, including omeprazole, the effect of these drugs on tonometric measurements is also critical before the application of this technique to hospitalized foals.…”

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confidence: 99%

Effect of Age, Feeding, and Omeprazole Administration on Gastric Tonometry in Healthy Neonatal Foals

Sanchez

Giguère

Javsicas

et al. 2008

Veterinary Internal Medicne

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Background: Gastric tonometry is commonly used in humans as an assessment of intestinal mucosal perfusion. Values in healthy foals are currently unknown.Hypothesis: Age, enteral feeding, and omeprazole administration would significantly alter gastric tonometry measurements in neonatal foals.Animals: Nine clinically normal foals were used to assess the effect of age and feeding, and 8 similar foals were used to assess the effect of omeprazole.Methods: At 1, 7, and 14 days of age, gastric intramucosal PCO 2 (PgCO 2 ) and arterial blood gas samples were obtained at baseline, immediately after feeding milk, and 1 and 2 hours after fasting for calculation of the intramucosal-arterial PCO 2 difference (DCO 2 ). To evaluate the effect of omeprazole, foals were evaluated twice as above, 2 hours after fasting, comparing administration of omeprazole to no drug.Results: There was a significant effect of age and feeding on PgCO 2 and DCO 2 , whereas arterial PCO 2 was not significantly affected by these factors. Postfeeding DCO 2 values were significantly lower than fasted values. Baseline and postfeeding DCO 2 increased with age. There was no significant effect of age on data collected after 1 or 2 hours of fasting. The 90% reference interval for DCO 2 data collected after fasting was 0-54 mmHg. Foals had a significantly higher mean gastric pH and significantly higher DCO 2 and PgCO 2 following omeprazole relative to no treatment.Conclusions and Clinical Importance: Because of the high and variable DCO 2 , which is exacerbated by omeprazole administration, the reference interval in foals is extremely wide.

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Does Gastric Juice pH Influence Tonometric Pco ₂ Measured by Automated Air Tonometry?

Cited by 19 publications

References 13 publications

In Viv o Predictive Dissolution: Transport Analysis of the CO 2 , Bicarbonate In Vivo Buffer System

In Viv o Predictive Dissolution: Transport Analysis of the CO 2 , Bicarbonate In Vivo Buffer System

Effect of prone position on hepato-splanchnic hemodynamics in acute lung injury

Effect of Age, Feeding, and Omeprazole Administration on Gastric Tonometry in Healthy Neonatal Foals

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Does Gastric Juice pH Influence Tonometric Pco 2 Measured by Automated Air Tonometry?

Cited by 19 publications

References 13 publications

In Viv o Predictive Dissolution: Transport Analysis of the CO 2 , Bicarbonate In Vivo Buffer System

In Viv o Predictive Dissolution: Transport Analysis of the CO 2 , Bicarbonate In Vivo Buffer System

Effect of prone position on hepato-splanchnic hemodynamics in acute lung injury

Effect of Age, Feeding, and Omeprazole Administration on Gastric Tonometry in Healthy Neonatal Foals

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Does Gastric Juice pH Influence Tonometric Pco ₂ Measured by Automated Air Tonometry?