Mohsen Nematy, Jacqui E O'Flynn, Liesl Wandrag, Audrey E Brynes, Stephen J Brett, Michael Patterson, Mohammad A Ghatei, Stephen R Bloom and Gary S Frost.
We would like to thank Dr Danna for his interest in our paper. He commented that 'measuring these gut peptides in fasting individuals only once per day in the morning is an incomplete representation of the physiology of these hormones in the complicated ICU patient'. We would therefore like to draw Danna's attention to the following points.
This was a pilot study in a group of intensive care patients. The idea of publication was to encourage debate around the role of gut hormones in this area, and to alert colleagues to our early findings. This was the first report in this field. We recognize the weaknesses of measuring one time point for gut hormones, but at the outset of the study we did not even know that interpretable data would be produced.
Previous publications from our group have defined the dynamic relationship between gut hormones, appetite and food intake [4–7]. We are aware that a detailed understanding requires the assessment of response to feeding, often achieved with a test meal. ICU patients tend to be fed continuously, however, thus rendering test meals practically difficult and of arguable significance. What is clear is that our understanding of appetite, food intake and the physiological mechanisms of the regulation of the same are poorly understood, and this is particularly important in recovering patients after discharge. This is a clear avenue for future studies.
We are not claiming to have anything like the whole answer with this pilot study, but suppressed ghrelin and elevated PYY may contribute to a reduced initial motivation to eat. We named this a pilot study and subsequently designed two investigations to examine the initial hypothesis and to explore the possible mechanism of observed changes in gut hormones in acute illness. These investigations were performed in elderly patients with a fractured neck of femur and in patients undergoing coronary artery bypass grafting surgery. Results were encouraging and will be submitted shortly for publication.