Objectives To study the incidence of significant hypocarbia (<4 kPa) and significant hypercarbia (>8 kPa) in ventilated infants <1500 g, or <32 weeks gestation and <8 day old. To evaluate the impact of medical trainee work patterns on the incidence of significant hypocarbia and hypercarbia.
Method Blood Gas (BG) results were retrieved for all eligible patients for June 2004–November 2006. The percentage of BG with significant hypocarbia/hypercarbia was calculated. Monthly percentages were also calculated to allow comparisons with NICU patient workload and starting periods for new trainees. The time of BG sample was used to match with trainee shift pattern.
Results A total of 8823 BG were identified and retrieved in 401 infants. Significant hypocarbia was found in 476 (5.4%) of BG in 182 (45%) infants. Significant hypercarbia was found in 1004 (11.4%) of BG in 234 (58%) infants There was wide variation in monthly incidence of both significant hypocarbia (1.7–12.4% of BG) and hypercarbia (2.3–17.6% of BG). This was not related to NICU activity. In the months when new trainees started the median monthly incidence of significant hypocarbia was 5.9% (IQR 4.9–9.1%) versus 4.3% (IQR 2.6–5.9%) in other months (p<0.05). This pattern was not seen for significant hypercarbia. Shift periods (night versus day) did not show differences in the incidence of hypocarbia or hypercarbia.
Conclusion The incidence of significant hypocarbia increases when new medical trainees start. This has implications for induction training and supervision of new trainees.