Do Changes in Plasma Osmolality Influence Ventilation?

Study Overview
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Brief Summary
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Primary hypothesis: osmolality changes influence the sensitivity of the respiratory center to carbon dioxide, hyponatraemia causing hyperventilation, and hypernatraemia depressing ventilation. Secondary hypothesis: There are gender differences in the sensitivity to osmolality changes. 10 women and 10 men will on different occasions drink water or receive hypertonic saline intravenously, in order to lower or increase plasma osmolality. The women will participate during both faces of the menstruation cycle. On each occasion the subject´s sensitivity to carbon dioxide will be tested, and blood samples will be drawn for analysis of blood gases,electrolyte and osmolality.Subjects who interrupt participation before completion of all planned occasions, will be substituted, so that 10 subjects of either sex will have participated as planned. All results from all participants will be analyzed.

Detailed Description
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Healthy volunteers will on different occasions be subject to reduced plasma osmolality caused by drinking water, and increased osmolality caused by intravenous infusion of hypertonic saline.Before and after each osmolality change, sensitivity to carbon dioxide will be tested by partial rebreathing through a so called Bain-system. Throughout the whole experiment heart rate, blood pressure and oxygen saturation will be recorded.Blood samples will be collected before each rebreathing test and every 20 minutes during the two hours of water or salt load. Urine will be collected and analysed.

Official Title
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Do Plasma Osmolality Changes Influence Ventilation, and Are There Gender Differences?

Conditions
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Hyponatraemia, Hypernatraemia

Intervention / Treatment
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* Other: Water
* Other: Saline 3%


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Females with regular menstruations, males Exclusion Criteria: Consumption of nicotine, BMI > 26, pregnancy,any hormone treatment, treatment with diuretics, diabetes or kidney disease, BMI > 26,

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Factorial Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Saline<br>The subjects will receive saline 3% intravenously for 2 hours, the volume calculated as 0.1 ml/kg/min. | Other: Water<br>* The subjects will drink tap water for 2 hours, volume calculated according to weight: 20ml/kg/hour.<br>* Other names: saline 3%;Other: Saline 3%<br>* The subjects will receive saline 3% intravenously for 2 hours, the volume calculated as 0.1 ml/kg/min<br>|
| Experimental: Water<br>The subjects will drink tap water for 2 hours, the volume calculated as 20ml/kg/hour | Other: Water<br>* The subjects will drink tap water for 2 hours, volume calculated according to weight: 20ml/kg/hour.<br>* Other names: saline 3%;Other: Saline 3%<br>* The subjects will receive saline 3% intravenously for 2 hours, the volume calculated as 0.1 ml/kg/min<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| pCO2 | pCO2,osmolality and sensitivity to CO2 will be recorded 10 minutes before before and 10 minutes after administering water or saline for two hours.The results will be analyzed for differences before and after osmolality changes in every single individual, and differences between females in luteal or follicular menstruation phase. | ten minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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carbon dioxide, ventilation, gender, osmolality, menstruation cycle