Blood transfusion mechanical ventilation

The combination of respiratory and metabolic alkalosis is the most common mixed acid-base disorder. This mixed disorder occurs frequently in critically ill surgical patients with respiratory alkalosis caused by mechanical ventilation, hypoxia, sepsis, hypotension, neurologic damage, pain, or drugs, and with metabolic alkalosis caused by vomiting or nasogastric suctioning and massive blood transfusions. It may also occur in patients with hepatic cirrhosis who hyperventilate, receive diuretics, or vomit, as well as in patients with chronic respiratory acidosis and an elevated plasma bicarbonate concentration... 

Darveau M, Notebaert E, Denault AY, et al. Recombinant human erythropoietin use in intensive care. Ann Pharmacother 2002 36 1068—1074. Hebert PC, Wells G, Martin C, et al. Do blood transfusions improve outcomes related to mechanical ventilation Chest 2001 119 1850—1857. Hebert PC, Wells G, Blajchman MA, et al, for the transfusion requirements in critical care investigators, Canadian critical care trials group. A multicenter, randonuzed, controlled clinical trial of transfusion requirements in critical care. N Engl J Med 1999 340 409-417. 

In a single-center non-randomized study in patients undergoing primary cardiac operations, 3334 were given aprotinin and 3417 were not [203 ]. The former were older, and had more unstable symptoms, lower ejection fractions, more preoperative hemodynamic support, more urgent operations, and more combined coronary or valvular operations. Postoperative bleeding and blood product transfusion were considerably reduced by aprotinin, as was median duration of mechanical ventilation. Aprotinin was not related to postoperative myocardial infarction, renal insufficiency, neurological dysfunction, or operative death. 

High muscle pH (above 7.45) is seen in children with a respiratory or metabolic alkalosis. As in acidotic states, respiratory and metabolic causes can be distinguished by the blood PCO2. Most of the children who have developed muscle alkalosis were alkalotic because of hyperventilation while on a mechanical ventilator or because of a metabolic alkalosis caused by the transfusion of large quantities of citrated blood. Muscle pH which is often higher than blood pH in these children has been observed as high as 7.70. 

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