Lay Abstracts

ALPINE: adoption of lung protective ventilation in patients undergoing Emergency laparotomy

Dr Maurizio Cecconi

In the UK, patients undergoing emergency abdominal surgery represent the biggest group of all surgical admissions. This group is also the sickest and at the highest risk of developing post-operative complications and even death. The commonest complications that occur after abdominal surgery involve the lungs and respiratory system, such as development of chest infection.

In Intensive Care Units, one strategy that has been used to treat patients with injured lungs is 'protective lung ventilation' (PLV), where patients are put on ventilator machines with specific settings which prevent further damage to the lungs and allow recovery time. This is a well-established strategy that is used across the world.

Recent studies have shown that using this 'protective strategy' may be beneficial in patients who are undergoing abdominal surgery and may decrease their risk of getting complications after surgery. Patients undergoing emergency surgery are at particular risk and we do not know how best to ventilate these patients in theatre.

Our study is designed to determine if PLV is being used when patients are undergoing emergency abdominal surgery and the effect it might have on the risk of developing post-operative respiratory complications.

We propose to collect data in association with the National Emergency Laparotomy Audit (NELA) to investigate this question, by the addition of a non-mandatory section to an existing data collection form. This section will record lung ventilation parameters during the operation and parameters to determine any post-operative respiratory complications. These patients will be followed up for 48 hours after surgery.

This study is extremely important as there appears to be wide variation in how these patients are currently being ventilated and it is unknown at present to what extent PLV has been adopted. This study will also look for a correlation between mode of ventilation and development of complications. This information could potentially reduce complications and deaths in this high risk group of patients.

Measuring total haemoglobin mass (tHbEmass) in ventilated patients - a feasibility Epilot study

Dr James Plumb

Oxygen is essential for life, and haemoglobin - the pigment in our red blood cells - carries it around the body.

If the concentration of haemoglobin in our blood falls beyond a certain level, we are said to be 'anaemic'. Being anaemic is common in people awaiting an operation: in fact, 30 out of every 100 patients are anaemic. Anaemia can also occur during an operation. The vast majority of patients on an intensive care unit (ICU) become anaemic early in their critical illness.

In all these patients, anaemia can result from blood loss, or from being given lots of fluids into veins, which 'dilutes' the haemoglobin. However, the relative role of these processes isn't known.

The way to find out is to measure the concentration of haemoglobin in the blood which tells you the proportion of haemoglobin relative to the 'water' (or 'plasma') it is carried in and the total amount of haemoglobin in the body ('total haemoglobin mass' or tHb-mass). From these, one can calculate whether a fall in haemoglobin concentration is due to an increase in the volume of the 'watery' component of blood (plasma) or a real fall in the amount of haemoglobin in the circulation.

It is possible to do this using a method called the 'optimised carbon monoxide re-breathing technique (16) - the so-called 'standard technique'. However, this requires a person to breathe in a special gas mixture, and hold their breath. We've worked out a way to use this technique when people are on a breathing machine ('ventilator') on intensive care or in the operating theatre - and would like to see if it is easily done.

This 'new technique' involves modifying some equipment that we normally use in the operating theatre. It does not require any new equipment. We hope to make measurements on 20 patients who are due to have an anaesthetic and to compare the results to those taken before the operation using the 'standard technique'.

Pre-emptive paracetamol for post-operative pain: a randomised, double-blind two-way cross-over trial

Dr John Williams
Paracetamol is commonly used to treat pain, including pain after surgery. However, it is not clear when the best time to give it is. Most doctors give this at the end of surgery. However some studies have suggested paracetamol works better to reduce pain if given before the surgeon cuts the skin. We would like to investigate this with a study. We will invite 50 people to take part in this study who are undergoing surgery on their neck. We will randomly assign patients to each group and one will receive paracetamol before surgery and the other will receive paracetamol after surgery. They will also receive an injection of salt water so both them and their doctor do not know which group they are in, as this can affect the results. Patients will be followed up for 24 hours after surgery and asked about pain, side effects and the amount of painkiller they used will be calculated from a machine. This will end their involvement in the study.

A randomised controlled trial of high-flow nasal oxygen (Optiflowâ„¢) in high-risk patients after cardiac surgery

Dr Vasileios Zochios

High-risk patients with lung disease who undergo cardiac surgery are at significant risk of postoperative complications leading to prolonged hospital stay. One method of reducing the risk of lung complications is to treat patients with non-invasive ventilation or continuous positive airways pressure postoperatively. However, this often requires admission to a high dependency unit or intensive care, and is uncomfortable because of the need for a tight fitting mask, as well as being labour intensive and costly. High-flow nasal oxygen is a new alternative as it provides warmed humidified oxygen at high flow, and also has been shown to assist breathing and improve recovery. It is comfortable during use and indeed may be more comfortable than standard (dry) oxygen via a facemask or nasal prongs. It may be administered on a normal ward, however its routine use in high-risk patients with lung conditions such as asthma, chronic obstructive pulmonary disease, recent chest infections and heavy smokers has not been tested before.

The primary aim of this clinical trial is to determine if prophylactic high-flow nasal oxygen therapy in cardiac surgical patients at high risk of developing postoperative pulmonary complications is associated with shorter hospital stay.

High-risk adult patients who are scheduled to undergo cardiac surgery will be recruited with full ethical approval and informed consent. Before surgery, each patient will perform a six-minute walking test under the supervision of a physiotherapist. This simple tests measures how far patients can walk in six minutes. Additionally, patients will undergo spirometry testing which is used to assess how well the lungs work by measuring how much air the patient inhales and exhales and how quickly they exhale. Patients will thereafter undergo surgery under general anaesthesia as they would normally. After the operation, they will be looked after following our recovery protocols, incorporating pain relief, regular physiotherapy, early mobilisation and eating and drinking, and removal of chest drains and tubes as soon as possible.

On arrival in the critical care area after their surgery, patients will be randomly assigned to receive supplemental oxygen via a soft facemask (standard group), or via high-flow nasal cannulae (intervention group). Patients will be administered oxygen for at least 24 hours after surgery.

Patients who develop breathing difficulty will receive treatment based on their clinical need. On the fifth or sixth postoperative day, they will repeat the walking test and spirometry. We will use a short questionnaire to determine if there is any difference in how patients feel they recovered before they leave hospital and how quickly they returned to normal activities after discharge, and also to evaluate how they tolerated either the facemask or high flow nasal cannulae.

We have used data from previous studies to calculate that we will need a total of 74 patients to take part in order to evaluate whether high-flow nasal oxygen leads to reduced length of hospital stay after high risk cardiac surgery, compared with usual care oxygen therapy.