Use of Lactated Ringer’s solution does not eliminate the risk of strong ion difference-related metabolic acidosis following on-pump cardiac surgery.

There is a growing interest in the effects of plasma sodium levels on postoperative outcomes. A trend of using balanced crystalloid solutions is based on the extensive data on chloride and the strong ion difference-related acidosis. However, effects of sodium are often overlooked in this context. The aim of the study was to establish the effects of the routine use of Lactated Ringer’s Solution (RL) on postoperative changes in sodium concentrations and whether these changes result in metabolic acidosis. We performed database analysis of 358 consecutive elective on-pump cardiac surgery cases in a tertiary referral university hospital. Approval from the institutional ethics committee was obtained for this study. Intraoperative fluid balance was 2726±1073 ml and the total volume of intravenous infusions in the first 24 hours was 5865 (±1073) ml, 95% of which was RL; 58% of the patients had metabolic acidosis with a base excess below (–)2 mmol L–1 on arrival at the intensive care unit. There was a significant correlation between a strong ion difference and base excess (p less than 0.01). A significant improvement in metabolic acidosis was noted within the first 24 hours, from a base excess of (–)2.49±2.8 to 0.32±2.6 mmol L–1 (p less than 0.001). All of the improvement in the base excess is explained by a change in the strong ion difference from the mean value of 31±4.3 to 34.2±3.6 mmol L–1 (p less than 0.001). Changes in the strong ion difference were primarily driven by changes in the serum sodium concentration, which were three-fold higher compared to those of chloride [–2.36 (±2.6) mmol L–1 (p less than 0.001) and 0.84 (±3.2) mmol L–1, respectively (p = 0.01)]. In conclusion, our data confirm that there is a direct correlation between a strong ion difference and base excess following on-pump cardiac surgery. The use of RL prevented significant hyperchloraemia, but did not eliminate the risk of strong ion difference-related metabolic acidosis. The change in the strong ion difference was primarily linked to perioperative changes in the serum sodium concentration.

Endotracheal tube positioning during neck extension in thyroidectomy.

OBJECTIVE: To evaluate the effect of body mass index and neck length on endotracheal tube movement during neck extension in thyroidectomy. METHODS: A prospective study was conducted of 30 patients undergoing thyroidectomy during an 8-month period. Patient characteristics were recorded and endotracheal tube displacement was determined. RESULTS: Mean body mass index was 27.8 kg/m2 (range, 17.5-34.7 kg/m2) and mean neck circumference was 43.2 cm (range, 28-56 cm). The mean (± standard deviation) upward displacement of the endotracheal tube during neck extension was 7.17 ± 5.87 mm. Patients with a larger body mass index had a significantly greater amount of tube displacement (R2 = 0.67, p < 0.0001), as did patients with a smaller neck length (R2 = 0.48, p < 0.0001). CONCLUSION: Neck extension results in upward displacement of the endotracheal tube. The amount of displacement is significantly higher in patients with a larger body mass index or shorter neck length. This has particular relevance for nerve monitoring in thyroidectomy.

Comparison of the Mapleson C system and adult and paediatric self-inflating bags for delivering guideline-consistent ventilation during simulated adult cardiopulmonary resuscitation.

There is a discrepancy between resuscitation teaching and witnessed clinical practice. Furthermore, deleterious outcomes are associated with hyperventilation. We therefore conducted a manikin-based study of a simulated cardiac arrest to evaluate the ability of three ventilating devices to provide guideline-consistent ventilation. Mean (SD) minute ventilation was reduced with the paediatric self-inflating bag (7.0 (3.2) l.min⁻¹) compared with the Mapleson C system (9.8 (3.5) l.min⁻¹) and adult self-inflating bag (9.7 (4.2) l.min⁻¹ ; p = 0.003). Tidal volume was also lower with the paediatric self-inflating bag (391 (52) ml) compared with the others (582 (87) ml and 625 (103) ml, respectively; p < 0.001), as was peak airway pressure (14.5 (5.2) cmH2O vs 20.7 (9.0) cmH2O and 30.3 (11.4) cmH2O, respectively; p < 0.001). Participants hyperventilated patients' lungs in simulated cardiac arrest with all three devices. The paediatric self-inflating bag delivered the most guideline-consistent ventilation. Its use in adult cardiopulmonary resuscitation may ensure delivery of more guideline-consistent ventilation in patients with tracheal intubation.