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How 'nil by mouth' instructions impact on patient behaviour

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VOL: 100, ISSUE: 39, PAGE NO: 32

Carolyn Best, BSc, RGN, DipHE, is clinical nutrition nurse specialist

Sue Wolstenholme, BNS, RGN, is respiratory clinical nurse specialist;Janet Kimble, RGN, is clinical nurse specialist, upper GI;Helen Hitchings, BSc, DipADP, Registered Dietitian, is acting nutrition and dietetic services manager;H.M. Gordon, MD, FRCP, is consultant gastroenterologist; all at the Royal Hampshire County Hospital

Preoperative fasting is a time-honoured tradition that minimises the risk of regurgitation and inhalation of gastric contents while under anaesthetic. Studies have shown that it is safe for patients to eat up to 6-8 hours before anaesthesia (Simini, 1999; Maltby, 1993; Hung, 1992) and drink up to 2-3 hours before (Maltby et al, 1991; Agarwal et al, 1989).

Preoperative fasting is a time-honoured tradition that minimises the risk of regurgitation and inhalation of gastric contents while under anaesthetic. Studies have shown that it is safe for patients to eat up to 6-8 hours before anaesthesia (Simini, 1999; Maltby, 1993; Hung, 1992) and drink up to 2-3 hours before (Maltby et al, 1991; Agarwal et al, 1989).

However, it is questionable how closely these findings are observed in clinical practice as there is often a discrepancy in fasting times recommended in patient literature and in their experience in hospital. Through discussion of a paper by Crenshaw (2002) at a nurses' journal club in the Royal Hampshire County Hospital a decision was made to assess our own hospital's performance on fasting times.

In her article, Crenshaw (2002) examines the discrepancy between recommended guidelines on preoperative fasting and clinical practice. The guidelines cited demonstrate that pulmonary aspiration from anaesthesia is a rare complication, and that consumption of food until six hours before elective surgery and fluids until two hours before is acceptable. However, Crenshaw found that in practice patients were fasting for longer periods (12-37 hours), supporting the findings of earlier studies (American Society of Anesthesiologists Task Force on Preoperative Fasting, 1999). UK studies have made similar findings (Seymour, 2000; Pearse and Rajakulendran, 1999).

As well as examining fasting times, we decided to explore the effect fasting had on patient comfort, because Hung (1992) and Smith (1997) had identified that inappropriate fasting may result in symptomatic dehydration or hypoglycaemia.

Thus the aim of the audit process was to determine:

- The instructed and actual durations of fasting for patients attending for radiological investigations or upper gastrointestinal endoscopic procedures;

- Whether the fasting resulted in adverse symptoms.

Development of the questionnaire
A working party was set up comprising two nursing members of the journal club, the nutrition nurse specialist and, to bring an overall trust approach, the deputy director of nursing.

There was much discussion about the variety of local guidelines for patients regarding perioperative/procedure fasting and instruction. While our own acute hospital has guidelines for preoperative fasting for elective surgical patients, the absence of any definitive national standards in this regard was noted.

Patients attending for radiological investigations or upper gastrointestinal endoscopic procedures were identified as appropriate for audit purposes, as these groups are provided with written information before their procedures detailing specific instructions on when to stop eating and drinking.

The authors established as precisely as possible exactly what information was required from patients who were involved in the audit. This was then translated into a simple, 12-point questionnaire (Fig 1).

The questionnaire was reviewed by the working party and adjusted several times before being piloted on a group of patients who were undergoing upper gastrointestinal endoscopy. No further adjustments were found to be necessary.

Data collection
Patients attending the medical imaging department were chosen as the first tranche to be questioned, for the following reasons:

- They provided examples of patients needing to fast for a variety of procedures;

- They had all received well-established written information about fasting with their appointment details;

- They were a large group of patients, with space and opportunity for interviewing.

A team of clinical nurse specialists (CNSs) were recruited as interviewers. Patients attending for appointments were asked whether they were prepared to be involved in the audit and were questioned about the instructions they had received.

All gave their consent and were directed to one of the CNSs, who provided an outline explanation of the rationale for the study and interviewed them using the patient questionnaire shown in Fig 1.

All the interviews were carried out in the space of one day. Following this, similar arrangements were made with the endoscopy unit.

In total, 46 patients were interviewed, of which 29 were attending for radiological investigations and 17 for upper gastrointestinal procedures.

Five patients from the radiological group stated that they did not understand the written instructions they had received before the procedure and so were not included in the subsequent analyses.

Patients were asked whether they understood why they had to fast - all 17 (100 per cent) of the endoscopy group stated they were aware of the rationale, but only 18 (75 per cent) of the medical imaging group did. Some 71 per cent of patients within both groups fasted for at least one hour longer than requested (see Table 1, p34) despite understanding the rationale for fasting.

It was not surprising to note that patients reported one or more symptoms of thirst, hunger or tiredness. Thirty-six patients (88 per cent) reported at least one symptom, with 14 of those (34 per cent) reporting two or more symptoms. The remaining five patients who reported no symptoms all belonged to the endoscopy group.

As thirst was a common complaint patients were asked whether they were aware of actions they could take to relieve a dry mouth. Only 39 per cent of patients were able to state an action to relieve this problem. Suggestions ranged from sucking an ice cube, chewing gum or brushing teeth. For those patients who were unaware of the appropriate action to take, interviewers suggested a sip of water washed around the mouth, chewing gum or brushing teeth.

Encouragingly, 93 per cent of patients were satisfied that they knew how or when to take their medication should it be required during the period they had been instructed to fast.

Some 23 per cent of the endoscopy group and 58 per cent of the medical imaging group were unsure when they could start to eat and drink again after their procedure. This information was not provided in the literature given to patients.

Chapman (1996) highlighted the need for comprehensive fasting instructions to minimise excessive fasting, while Crenshaw (2002) maintains that oral instruction is required to add clarification. The patients in our study were provided with clearly written instructions on the period they were expected to remain nil by mouth, but in some instances chose to fast for longer than required.

While excessive fasting has been associated with changes in theatre lists (Jester and Williams, 1999), tradition (O'Callaghan, 2002), or lack of knowledge (Crenshaw, 2002), patients in our own study were given specified fasting times but had themselves chosen to extend their fast.

When asked why they had stopped eating or drinking earlier than required, a number of patients stated that they thought it would be in their interest and would reduce the risk of vomiting during the procedure. One patient had followed fasting times recommended from a previous investigation, which were longer.

During the interview process patients took the opportunity to discuss a variety of issues. Some appeared to be unaware of which investigation they were about to undergo and the rationale for that procedure, despite receiving a letter detailing this information. This vindicated our decision to involve senior nurses in the interviews.

We would suggest that the written instructions sent out to patients need to be adapted to:

- Reassure patients that they can and should maintain their oral intake until being instructed to stop;

- Provide information on oral comfort during fasting;

- Provide details stating when patients can begin to eat and drink after their procedure.

Despite receiving clear written instructions, a significant number of patients in our study chose to fast for periods longer than recommended. This resulted in reports of adverse symptoms, most noticeably thirst and hunger. Both specialist areas involved within this audit have now re-examined their patient information to accommodate the above findings.

- This article has been double-blind peer-reviewed.

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