HYPOXEMIC RESUSCITATION IN NEWBORN PIGLETS - RECOVERY OF SOMATOSENSORY-EVOKED POTENTIALS, HYPOXANTHINE, AND ACID-BASE-BALANCE

We tested the hypothesis that hypoxic newborn piglets can be successfu lly resuscitated with lower O-2 concentrations than 21%. Severely hypo xic, 2-4-d-old, anesthetized piglets were randomly divided into five r esuscitation groups: 21% O-2 (n = 10), 18% O-2 (n = 9), 15% O-2 (n = 9 ), 12% O-2 (n = 8), all normoventilated, and a hypoventilated 21% O-2 group (Paco(2); 7.0-5.0 kPa, n = 9). Base excess (BE) reached -20 +/- 1 mmol/L at the end of hypoxia. After 3 h of resuscitation, BE had ris en to -4 +/- 1 mmol/L in the 21% O-2, 18% O-2, and hypoventilated grou ps, but was -10 +/- 2 mmol/L in the 15% O-2 group (p < 0.05 versus 21% O-2 group) and -22 +/- 2 mmol/L in the 12% O-2 group (P < 0.05 versus 21% O-2 group). Four animals died during resuscitation, all allocated to the 12% O-2 group (p < 0.05 versus 21% O-2 group). Somatosensory e voked potentials (SEPs) recovered in 39 of 45 piglets, and remained pr esent during resuscitation in all except the 12% O-2 group. SEP recove red initially even in six of eight animals in the 12% O-2 group, but d isappeared again in all later during resuscitation. The SEP amplitude recovered to levels not significantly different from the 21% O-2 group in all groups except the 12% O-2 group. Plasma hypoxanthine concentra tions and extracellular hypoxanthine concentrations in the striatum de creased during resuscitation to levels not significantly different fro m the 21% O-2 group in all but the 12% O-2 group (p < 0.05 versus 21% O-2 group). In conclusion, severely hypoxic newborn piglets were resus citated as efficiently with both hypoventilation and 18% O-2 as with 2 1% O-2.