The oesophagus is a muscular thin‐walled tube approximately 25 cm long and about 2 cm in diameter. It is located behind the trachea and in front of the vertebral column. It begins at the inferior end of the laryngopharynx and ends at the stomach. There are two sphincters within the oesophagus: the upper or hypopharyngeal sphincter and the lower gastro‐oesophageal or cardiac sphincter. The upper moves food from the pharynx to the oesophagus and the lower enables the food to pass into the stomach. The oesophagus has three layers – the mucosa, submucosa and muscularis – with the innermost layer consisting of stratified squamous epithelium (Tortora and Derrickson [243]).

The stomach connects the oesophagus to the small intestine or duodenum. It is a J‐shaped dilated portion of the alimentary tract and one of its functions is as a holding reservoir and mixing chamber. It is located between the epigastric, umbilical and left hypochondriac regions of the abdomen. It is divided into four regions: the cardia, fundus, body and pyloric part. Distally, the pyloric sphincter is located between the stomach and the duodenum. The stomach has three muscle layers to allow for gastric motility to move the contents adequately whereas other parts of the alimentary tract only have two muscle layers (Tortora and Derrickson [243]).

The duodenum is part of the small intestine. It is approximately 25 cm long and 3.5 cm in diameter and is the shortest region. It begins at the pyloric sphincter of the stomach and joins the jejunum. Both the pancreas and the gallbladder release secretions into the duodenum (Tortora and Derrickson [243]).

A gastroscopy is undertaken to investigate symptoms originating from the upper GI tract, such as reflux and dysphagia. The doctor or nurse endoscopist uses direct vision to diagnose, sample and document changes in the upper GI tract.

In some centres, nurse endoscopists work alongside medical endoscopists to undertake endoscopy. In 1995, the British Society of Gastroenterology began to support the development of non‐medical endoscopists. The nurse endoscopist must work within their own professional boundaries and complement the medical endoscopist teams (BSG [28], Smith and Watson [231]). Studies have shown that nurse endoscopists perform procedures at a high standard and adhere to international standards, and most patients had no specific preference for a doctor or nurse endoscopist and expressed high satisfaction (Tursi [244], Van Putten et al. [248]). It is essential that all practitioners are adequately trained in the administration of conscious sedation and are aware of its side‐effects and reversal agents. Conscious sedation is used to relax the patient, minimize pain during the procedure and improve procedural efficiency (Choi [33]). Clinical units must also limit the possibility of overdose, particularly with midazolam, as highlighted by the National Patient Safety Agency (NPSA) ([169]).

It is essential that valid consent is obtained prior to any investigation, as previously discussed in this chapter. This is important as conscious sedation may be utilized during this procedure.

It is a priority that an organization providing endoscopic services has clear, identifiable policies and procedures. There must be open, bidirectional communication between the department, organizational board and national bodies to ensure that appropriate care is delivered. Monitoring processes must be in place to identify potential clinical or organizational risks, and there must be a clear reporting mechanism.

The organization must ensure that relevant policies and procedures are in place to reduce risk. Responding to national alerts and guidance is essential, as is implementing relevant evidence. In 2008, the NPSA ([169]) issued an alert regarding the use of midazolam during conscious sedation. It had been found that some patients were receiving an overdose of midazolam with a subsequent over‐reliance on the use of flumazenil as a reversal agent.

To conduct a gastroscopy, a flexible side‐ or end‐viewing endoscope is required. The endoscope allows visualization of the oesophagus, stomach and proximal duodenum (Chernecky and Berger [32], MacKay et al. [130], Pagana and Pagana [177], Smith and Watson [231]). Access to resuscitation equipment is also essential if conscious sedation is going to be administered (BSG [29]).

A medical and nursing history and assessment must be undertaken to identify any care needs or concerns that may be significant, in particular the patient's current drug therapy, drug reactions and allergies, any organ dysfunctions (such as cardiac and/or respiratory disease), and previous and current illnesses. It is also important to be aware of any coagulopathies, as samples of tissue or biopsy may need to be taken during the procedure. This can be pre‐empted by reviewing blood results prior to the gastroscopy. A set of observations (including temperature, pulse, blood pressure, respiration rate and oxygen saturations) should also be taken to identify any pre‐procedural abnormalities and provide a baseline. If the patient has diabetes, their blood glucose level should be checked (BSG [26], [29], MacKay et al. [130], Pagana and Pagana [177], Smith and Watson [231]).

Prior to the procedure, a local anaesthetic spray may be used on the back of the throat. In some cases, conscious sedation may be administered. This technique involves the administration of a benzodiazepine such as midazolam in small doses. Doses must be titrated for elderly patients or those with co‐morbidities such as cardiac or renal failure (BNF [16]). Oxygen therapy should also be administered for patients at risk of hypoxia and those requiring sedation. Generally, 2 L per minute is adequate for most circumstances to maintain oxygen saturation levels and prevent hypoxaemia (BSG [26], [29]).

The patient must fast for at least 4–8 hours prior to the gastroscopy to ensure that the stomach is relatively empty. Clear fluids may be taken up to 2 hours before, but local guidelines must be followed. This increases the visual field for the endoscopist and also minimizes the risk of aspiration if the patient vomits (Kang and Hyun [111], Saied et al. [217]). If the patient has undergone previous gastric surgery, this fasting time may be longer, depending on the type of surgery, to ensure gastric emptying (Ahn et al. [4]).

The nurse can assist by getting the patient to lie on their left side on the trolley (Chernecky and Berger [32], Pagana and Pagana [177], Smith and Watson [231]). If a sedative is used, it is essential that the patient is monitored with pulse oximetry and observed for any respiratory depression. Nursing staff can observe and record oxygen saturations and respiratory rate. ECG (electrocardiography) monitoring may only be required if a patient is at risk of cardiac instability during the procedure (BSG [26]).

Physiological monitoring must continue in the immediate recovery period. Supplemental oxygen and oxygen saturations may be required, especially if a sedative has been used. The patient should avoid drinking or eating for an hour after the use of the throat spray to minimize the risk of aspiration. Once stable, awake and reviewed by the team, the patient may be discharged or transferred to another department (BSG [26], [29]).

It is recommended that patients who have been sedated with an intravenous benzodiazepine do not drive a car, operate machinery, sign legal documents or drink alcohol for 24 hours (BSG [26]). This is irrespective of whether their sedation has been reversed with flumazenil. The patient must be accompanied home if they have been given a sedative. The accompanying adult should stay with the patient for 12 hours at home if they live alone. It is important to remember that aspiration pneumonia may develop hours or days later and the patient should be informed to report any symptoms such as temperature or breathing difficulty (BSG [26], [29], Smith and Watson [231]).

Any samples should be clearly documented with the appropriate forms, as previously discussed in this chapter. All drugs administered, complications and/or findings should be documented.

If oversedation occurs, respiratory function will be affected. It is essential that close monitoring occurs during and after the procedure. A reversal agent may be required, such as flumazenil for midazolam (BSG [26], NPSA [169], Pagana and Pagana [177], Smith and Watson [231]).

Although rare, it is possible that perforation of the oesophagus, stomach or duodenum may occur. Further medical and/or surgical intervention will be required to manage this potential complication (Borgaonkar et al. [18], Pagana and Pagana [177], Smith and Watson [231]).

Where biopsy samples have been taken, this may increase the risk of post‐procedural bleeding. Further intervention may be required to stop the bleeding. Patients should be advised to seek medical assistance if, following discharge, there are signs of bleeding that include the presence of fresh blood in the sputum and melaena (Chernecky and Berger [32]).

This will be dependent on the specific aetiology of the bleed; for example, if it is from varices, variceal band ligation may be required (Borgaonkar et al. [18], Pagana and Pagana [177], SIGN [229], Smith and Watson [231]).