The impact of systemic pH on cardiac function and clinical outcome in the critically ill patient
- Titration studies in animals with normal cardiac function show that a reduction in blood pH (and presumably that of the intracellular and interstitial compartments) from the normal level of 7.40 to 7.20 is associated with a rise in cardiac output. However, when blood pH is less than 7.20, cardiac output is reduced. Similar studies in humans with or without normal cardiac function have not been done, and yet blood pH at which aggressive treatment is recommended has been set at 7.20 based solely on animal experiments. We hypothesize that a change in blood pH in humans will also affect cardiac function, but the level of blood pH at which this is observed might be similar or different in humans. In addition, the presence or absence of underlying cardiac disease and the type of acid-base abnormality present might modify the response of the heart to changes in blood pH.
- Assess whether there are significant changes in cardiac function associated with changes in blood pH.
- Relate the changes in cardiac function to presence or absence of underlying cardiac disease.
- To establish which factors affected by blood pH have an impact on cardiac function.
- Study the mortality of patients admitted to the Intensive Care Unit (ICU) who had continuous cardiac monitoring at any time during their admission and relate it to changes in blood pH.