Assessment of a modified four-category classification of urgency of caesarean section.

A four-category urgency classification for caesarean section (CS) based on clinical definitions was introduced in 2000. However, clinical application remains inconsistent. We proposed that modification of the wording of these definitions might improve consistency of assignment of urgency. A total of 349 maternity professionals applied an urgency category to 10 hypothetical cases of CS, using either the original or a modified classification. There was a supplementary question relating to urgency category in relation to the 30 minute decision-to-delivery time standard. The commonest urgency categories applied to the cases by the respondents were: Category 1: cord prolapse, significant placental abruption, maternal cardiorespiratory distress; Category 2: late fetal heart rate decelerations, CS pre-booked to avoid vaginal delivery but woman presents in advanced labour, bleeding placenta praevia without hypovolaemia, failed instrumental delivery with no fetal compromise; Category 3: deteriorating but compensated maternal medical condition; Category 4: operation at short notice but no clinical urgency. Consistency of responses in individual cases varied from 0.92 down to 0.55. Some 66% of respondents believe that only Category 1 cases should be included in a 30 minute decision-to-delivery time standard, whereas 34% would include Category 2 as well as Category 1 in this standard. The consistency of responses did not differ between the original and modified urgency classifications. Inter-rater reliability was better when comparing the answers from obstetricians compared with anaesthetists or midwives. This study found that the proposed modifications did not improve the consistency of application, and that any changes to the current classification should not be introduced without thorough investigation.

Assessment of the Hewlett-Packard HP47210A capnometer.

The Hewlett-Packard HP47210A Capnometer, a "mainstream" infra-red carbon dioxide analyser, has a sensor in-line with the patient circuit. The calibration apparatus is included within the unit, and an internal microprocessor corrects for the presence of nitrous oxide and varying concentrations of oxygen. Maximum error was 0.37 kPa for carbon dioxide partial pressures less than 5.3 kPa, and less than 3.6% for partial pressures of carbon dioxide greater than 5.3 kPa.