Figure 4. Arterial pH over the first 120 hours of life, expressed as mean ± SEM at 12-hour intervals. Alkalosis was achieved rapidly and maintained in eras 1 and 2. No attempt to alkalinize was made in era 3. Arterial pH was significantly different across the eras at all time points except 12 hours. This effect was maintained across eras and increased over time (time*era effect, p = 0.0003).