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Neonatal Blood Gases and Outcome Following Perinatal Asphyxia |
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Correspondence
Address : Dr Christopher Geoffrey Alexander Aiken, 729 Frankley Road, New Plymouth 4371, New Zealand. Phone: +64 6 753 2950 Email: geoffaiken@xtra.co.nz |
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Objective: To determine how well neonatal blood base excess and lactate predict outcome following perinatal asphyxia. Study Design: Over 68 months, with around 9000 deliveries, lactate was measured on all blood gases taken from neonatal admissions, as well as mineral base and organic acid whenever electrolytes were required. Infants were classified according to their outcome more than 10 years following perinatal asphyxia. Blood gases affected by other causes of acidosis were excluded. Group I 490 unaffected, including need for resuscitation Group II 22 unaffected following mild hypoxic ischaemic encephalopathy Group III 5 unaffected following moderate hypoxic ischaemic encephalopathy Group IV 11 disability after acute asphyxia Group V 8 disability after chronic intrauterine hypoxia Group VI 5 died from perinatal asphyxia Logarithmic regression equations of base excess, lactate and organic acid against postnatal age for the first 48 hours were calculated for each group. Results: Lactate equations increased progressively with the severity of perinatal asphyxia, with similar equations and outcome for groups II and III as well as for groups IV and V. Base excess equations did not increase uniformly and underestimated the severity of asphyxia in group V, because of high mineral base soon after delivery. Organic acid equations ran parallel with lactate but were also increased by low glomerular filtration. Conclusion: Blood lactate during the first 48 hours predicted the risk following perinatal asphyxia. Lactate above 10 mmol/L at 1 hour indicated risk of adverse outcome, as well as levels above 5 mmol/L after 4 hours, when other causes of acidosis had been excluded. Base excess correlated poorly with lactate because of wide variation in mineral base. It failed to detect chronic in utero hypoxia and was of no value in predicting risk after 8 hours. |
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