Blood oxypurines and erythrocyte 2, 3-diphosphoglycerate levels at high altitude hypoxia

Significance of serum uric acid in patients with chronic respiratory failure treated with non-invasive positive pressure ventilation

PURPOSE

The aim of the study was to evaluate serum uric acid (UA) levels before and after non-invasive positive pressure ventilation (NPPV) to assess the utility of serum UA as an indicator of acute exacerbation of chronic respiratory failure (CRF) in patients treated with NPPV.

METHODS

We analyzed change in the serum UA level in 29 patients with CRF due to restrictive thoracic disease and treated with NPPV.

RESULTS

After NPPV therapy, PaO2 was significantly increased and PaCO2 was significantly decreased in all patients. Sixty-two percent of patients (18 of 29) showed a decreased serum UA/creatinine (Cr) ratio after NPPV therapy, but, overall, there was no significant change in serum UA/Cr (P=0.0688). The change in serum UA/Cr was not correlated with the changes in PaO2 and PaCO2 after NPPV. When we compared patients in whom serum UA/Cr decreased (n=18) with patients in whom serum UA/Cr did not decrease (n=11), there were significantly fewer patients who suffered CRF exacerbation in the group with a decrease (P=0.0021). Furthermore, the cumulative proportion (Kaplan-Meier) of patients who did not suffer exacerbation of CRF was significantly higher in the group in which serum UA/Cr decreased (P=0.0003).

CONCLUSIONS

Our data suggest that serum UA may be a useful clinical indicator of CRF exacerbation in patients treated by NPPV.

Plasma hypoxanthine and exercise

During exercise, ATP is converted to ADP and AMP to supply energy for muscular contraction. It is then regenerated via various pathways of intermediary metabolism. However, with high levels of exercise, net ATP degradation in muscle occurs. In exercise and other clinical situations, adenine nucleotide degradation leads to an accumulation of degradative purine products including hypoxanthine. In an effort to monitor events of energy metabolism, we examined plasma hypoxanthine levels at various exercise intensities. Peak plasma hypoxanthine levels after maximal exercise (18.9 +/- 2.6 microM, mean +/- SEM) were significantly greater than resting levels (1.1 +/- 0.1 microM; p less than 0.001). Hypoxanthine levels after steady state exercise at 52, 76, and 97% of ventilatory threshold did not exceed resting levels. However, plasma hypoxanthine rose significantly after exercise at 124% of ventilatory threshold (6.3 +/- 1.0 microM; p less than 0.01) and at 152% of ventilatory threshold (17.0 +/- 3.6 microM; p less than 0.001). Exercise at subventilatory threshold intensity (74% of ventilatory threshold) for a prolonged time period, such that total work equaled that performed at 152% of ventilatory threshold, did not elevate hypoxanthine levels (0.46 +/- 0.1 microM) above resting values. We conclude that elevation of plasma hypoxanthine levels occur during exercise at intensities that exceed the ventilatory threshold and indicate that net adenine nucleotide degradation has occurred.

Accuracy of Apgar score and arterial cord-blood pH in diagnosis of perinatal brain-damage assessed by CK-BB isoenzyme measurement

This study was carried out on 45 newborns to evaluate the accuracy of 1 minute Apgar score and umbilical arterial pH for prediction of the risk of perinatal brain damage. Using a new and very sensitive method for CK-BB determination, which is considered a good indicator of brain damage, CK-BB was used as reference. Patients with low Apgar score at one minute of life had significantly higher cord blood CK-BB values than the control group (p less than 0.01). No difference was found between the control group and the group with umbilical cord blood acidosis (p less than 0.2).