891 Fasting Times in Trauma List Patients

Introduction

To reduce the risk of regurgitation and aspiration of gastric contents, patients are to fast before anaesthesia. However, prolonged periods of fasting have been found to be unnecessary and potentially harmful. Our aim was to compare pre-operative fasting times in trauma patients against the AAGBI (Association of Anaesthetists of Great Britain and Ireland) guidelines and highlight areas for improvement. The AAGBI recommends minimum fasting periods of:

Method

50 patients were audited in each cycle. Data were collected prospectively using questionnaires in the initial audit and by interviewing patients in the re-audit. Patients in ITU and those with dementia were excluded. Questions included fasting instructions given, time of the last meal and drink (including kind of drink), IV fluids administration. Anaesthetic notes were checked for time of induction of anaesthesia.

Results

Average time fasted for food was 17.09 hours and 9.32 hours for water. In the re-audit, average time fasted was 16.43 hours for food and 5.27 hours for water. All the patients received information as to when they could eat or drink until. None of them was told ‘midnight’.

Conclusions

Although there was an improvement, this was still beyond the guidelines. The results highlighted the importance of regularly reviewing the fasting status throughout the day in order to achieve the standard.

Macrophages use different internalization mechanisms to clear apoptotic and necrotic cells

The present study characterized two different internalization mechanisms used by macrophages to engulf apoptotic and necrotic cells. Our in vitro phagocytosis assay used a mouse macrophage cell line, and murine L929sAhFas cells that are induced to die in a necrotic way by TNFR1 and heat shock or in an apoptotic way by Fas stimulation. Scanning electron microscopy (SEM) revealed that apoptotic bodies were taken up by macrophages with formation of tight fitting phagosomes, similar to the 'zipper'-like mechanism of phagocytosis, whereas necrotic cells were internalized by a macropinocytotic mechanism involving formation of multiple ruffles directed towards necrotic debris. Two macropinocytosis markers (Lucifer Yellow (LY) and horseradish peroxidase (HRP)) were excluded from the phagosomes containing apoptotic bodies, but they were present inside the macropinosomes containing necrotic material. Wortmannin (phosphatidylinositol 3'-kinase (PI3K) inhibitor) reduced the uptake of apoptotic cells, but the engulfment of necrotic cells remained unaffected. Our data demonstrate that apoptotic and necrotic cells are internalized differently by macrophages.