Monitoring of respiration: pulse oximetry, capnography, oximetry
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Posted On :
Dec-26-2011
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Article Word Count :
686
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In carrying out cardio-pulmonary resuscitation (CPR), ventilation with oxygen or oxygen-air mixture provides a normal or near normal arterial blood oxygenation.
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However, the minute volume of circulation in heart massage is usually 3-5 times less than normal, because of what the oxygenation of absolutely insufficient; therefore growing rapidly pronounced metabolic acidosis, which is partly "quenched" bicarbonate buffer of the organism with the formation of significant amounts of C02. Voltage SOA in the tissues and venous blood increases with great rapidity, and the carbonation blood during a massage of the heart to the lungs.
During the resuscitation of removal of CO2 from the atmosphere into the body breaks down. Small blood flow can not cope with the elution of C02 from the tissue, and pulmonary gas exchange efficiency is sharply reduced, and for two reasons.
First, the small blood volume per minute is unable to maintain a sufficiently high pressure in the pulmonary artery to ensure blood supply to all regions of the lung, so blood flow is directed mainly to the lower zones of the lungs, and upper and middle sections turn into the alveolar dead space.
Secondly, the increased alveolar pressure during mechanical ventilation during resuscitation is often done in an explicit mode of hyperventilation, also shifts the capillary blood flow in the lower parts of the lungs. Studies have shown that with standard CPR in tidal volume of 60-70% is spent on ventilation of the alveoli drained, that is, alveolar dead space and gas exchange occurs only in 30-40% of lung tissue.
During resuscitation PetCO2 significantly reduced due to violations of CO2 delivery to the lungs small minute volume of circulation and the formation in the lungs expressed the alveolar dead space, dramatically reducing the efficiency of ventilation.
If you do not have CPR independent of heart rate, chest compressions is usually kept at 0.5-2.5 RetS02%.
It is believed that cardiac massage is effective, if RetSO2 than 1% (7 - 8 mm Hg. Art..)
Inability to raise this parameter to 1% - a fact very significant: it indicates, as a rule, the presence of additional challenges to effective resuscitation. They are:
• intubation of the esophagus;
• displacement of tracheal tube in the bronchus;
• hypovolemia;
• cardiac tamponade;
• air block;
• massive pulmonary embolism;
• hyperventilation;
• failure to comply with CPR techniques.
RetSO2 rise during CPR to 15 mm Hg. of Art. and higher - a sign of increased minute volume of blood circulation. This usually means self-renewal of blood flow.
In the absence on the grounds of elektrokardiomonitora tried to restore cardiac activity. If you want to interrupt resuscitation etom.ne for pulse palpation, and the method itself does not give artifacts, so characteristic of the ECG.
If the minute volume of circulation approaching normal RetS02 increases rapidly to its initial level and may even exceed it for as long as the body will not be displayed excess carbon dioxide that has accumulated during resuscitation.
It should be remembered and the other probable cause lifting PetCO2 during resuscitation - infusion of sodium bicarbonate, which, once in the blood and tissue, rich lactate and other acidic products of anaerobic metabolism, neutralize them with the formation of a large amount of CO-. "And a significant increase in the respiratory component acidosis. Intravenous injection of sodium hydrogen carbonate solution in CPR is rezchayshee increase of CO2 in the venous blood flowing to the lungs, and a corresponding rise RetSO2.
After intravenous infusion of sodium bicarbonate during resuscitation voltage C0, in the venous blood at times reaches 100 - 130 mm Hg. of Art.
In clinical practice, often there are times when the appearance of the ECG normal (or normal-like) bioelectrical activity of the heart is not accompanied by restoration of blood flow (EMD - electromechanical dissociation) **. If this phenomenon does not recognize the right moment to stop and massage the heart, is a real threat of irreversible brain damage. Today kapnogra-raphy - perhaps the only one available in the general practice, objective method that allows you to immediately assess the effectiveness of heart and decide to terminate or to continue cardiac massage.
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Article Source :
http://www.articleseen.com/Article_Monitoring of respiration: pulse oximetry, capnography, oximetry_124615.aspx
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Author Resource :
In cases where the occurrence of cardiac rhythm on the ECG is not accompanied by a rapid and significant rise of Pm-SOD, it is necessary to continue cardiac massage and drug therapy to restore an effective heart rate. Pulse oximeter.
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Keywords :
oximeter,
Category :
Health and Fitness
:
Medicine
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