ARDs_Lecture[1] - RESPIRATORY: Adult Respiratory Distress...

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RESPIRATORY: Adult Respiratory Distress Syndrome (ARDS) Ventilation Perfusion Ratio Ventilation (air flow) and perfusion (blood flow == VQ ratio) In normal physiology, segments of the lung ventilate and perfuse with differing efficiency. Apex of the lung ventilation exceeds perfusion. (high VQ ratio) Base of the lung perfusion exceeds ventilation. (low VQ ratio) Averages out to a V/Q ratio of R= 0.8 Low V/Q ratio= SHUNT. You have more perfusion than ventilation. This is usually because caused by a blockage of some sort or fluid filled alveoli/pneumonia. High V/Q ratio = EMBOLI. More Air comes in and there is low perfusion/low blood flow which can be caused by a blood clot, excess bleeding, or shock Gas Exchange (external Respiration) At the tissue level (internal Respiration) Gases exerts a partial pressure in the blood pCO2, PaO2 PaO2 Partial pressure of oxygen Amount dissolved in plasma (3%) Norm: 80-100 mmHg SaO2(SAT) Amount of O2 saturated or bound to the hemoglobin ( This is tested by blood sample , where as, SpO2 is measured by pulse oximetry ). Norm: > =97% PaCO2 Is exhaled after leaving the tissues 35-45 Arterial Blood Gases NORMALS : pH 7.35 – 7.45 1
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PaCO2 35 – 45 mm Hg PaO2 80 – 100 mm Hg HCO3 22 – 26 mEq/L SaO2 >97% pH pH >7.45, IT IS ALKALOSIS . pH <7.35, IT IS ACIDOSIS . Assess PaCO2 Respiratory acidosis: > 45mm Hg Respiratory alkalosis: < 35mm Hg Assess HCO3 Metabolic acidosis: < 22 mEq/L Metabolic alkalosis: >26 mEq/L Determine Acid-base Determine pH 7.32 is it acid or base acid pCO2 50 is it acid or base acid HCO3 24 is it acid or base normal Determine the Oxygenation PO2 85 is it high, low or normal Normal SAT 97% is it high, low or normal Normal Respiratory acidosis with Normal Oxygenation Interpret 7.48 Base 35 Normal 29 High Metabolic Alkalosis 7.23 Acidic 2
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55 High 22 Normal Respiratory Acidosis Fully Compensated The other system is trying to compensate for the abnormality If compensation is present: both PaCO2 and HCO3 are abnormal and pH is normal The more deviant component is the primary disorder pH 7.35, CO2 55, HCO3 28 has a closer ph to acidosis Partial Compensation The other system is starting to compensate but has not completed the process All values are abnormal pH 7.33, CO2 49, HCO3 32 – partially compensated respiratory acidosis Here the base is trying to compensate for too much acid The pH is nearing normal Determine Partial Compensation by the 7.4 rule Use 7.4 as the midpoint of determining whether the blood gas was acid or base < 7.4 it is in the acid side > 7.4 it is on the base side Practice ABGs are on Bb Arterial Blood Gases (ABGs) are normally taken in the radial artery. If the radial artery isn’t able for use, then the femoral artery is normally used. Allen Test- Occlude both arteries (radial and ulna), allow the hand to turn
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This note was uploaded on 05/04/2008 for the course NURS 240 taught by Professor Harmon during the Spring '08 term at Lady of the Lake.

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ARDs_Lecture[1] - RESPIRATORY: Adult Respiratory Distress...

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