Virtual reality (VR) uses computer technology to create a three-dimensional environment which the user can explore and interact with. VR can be used to distract the patient during an operation and has been used to avoid sedative premedication, increase patient satisfaction and decrease pain during nerve blocks. VR used alongside spinal anaesthetic for hip, knee and ankle operations has shown a trend of less sedation being required with no decrease in patient satisfaction.

The most common type of anaesthesia given during total knee arthroplasty (TKA) is spinal. Spinal anaesthesia is given unless there are complications or other conditions present, and general anaesthesia is given instead. General anaesthesia puts the patient to sleep during the operation, whereas spinal anaesthesia allows the patient to stay awake, but numbs the lower half of the body so no pain is felt. Sedation is usually given with spinal anaesthesia to make the patient relaxed and sleepy. Light sedation will allow the patient to be awake but relaxed, whereas deeper sedation means the patient is more likely to be asleep and less likely to recall what happened during the operation. Sedation can cause a number of side effects including nausea, vomiting, headache, drowsiness, pain, confusion, memory loss and breathing difficulties.

In this study, all patients will receive spinal anaesthesia. Group 1 will receive VR and a light level of sedation, whilst Group 2 will not receive VR but will receive a deeper level of sedation (standard of care). When using VR during TKA, a lighter level of sedation should be required. This could help to reduce side effects and aid quicker patient recovery. This pilot study aims to investigate this further.

Total joint arthroplasty (TJA) is a successful surgical intervention to reduce pain and immobility from osteoarthritis. Mortality rates following TJA are low and survival has been increasing over the last two and a half decades despite an ageing population with a higher frequency of comorbidities.

Perioperative virtual reality (VR) is a non-pharmacological technique which has been used effectively to avoid sedative pre-medication, increase patient satisfaction and alleviate procedural pain during nerve blocks. VR has been successfully utilised across different medical specialties to reduce patient anxiety associated with interventions including magnetic resonance imaging (MRI), physical therapy, dental pain, and change of burns dressings. Furthermore, a trend towards less propofol sedation with use of VR has been found in spinal anaesthetic for hip, knee and ankle operations, with no decrease in patient satisfaction. However, this small pilot study did not investigate any other outcomes other than type and amount of sedation and duration of surgery. VR use has also been shown to reduce fentanyl dose, midazolam use and pain in elective total knee arthroplasty (TKA) patients who received a pre-operative adductor canal catheter. Satisfaction of patient, surgeon and anaesthetist has also been compared when using VR and using sedation with midazolam in patients undergoing urologic surgery under spinal anaesthesia. The patient and anaesthetist satisfaction scores were significantly higher in the VR group than in the sedation group.

Sedation is associated with a number of post-operative complications including nausea, hypo/hypertension, lower respiratory tract infection, cardiac arrhythmias, peripheral nerve damage, and post-operative delirium (PD). Nausea is a common occurrence following surgery with reported incidences of 30% in all post-surgical patients and up to 80% in high-risk patients. Dose dependent hypotension is the common complication in patients who have received propofol sedation, particularly in volume depleted patients. A common cardiovascular complication during anaesthesia is arrhythmia, with 70% of patients having arrhythmia undergoing general anaesthesia for various surgical procedures. Further complications associated with propofol, although more uncommon, include hypertriglyceridemia, pancreatitis and allergic complications.

The incidence of PD is generally higher after hip fracture surgery (4-53.3%) compared to elective hip surgery (3.6-28.3%). Independent risk factors for developing inpatient delirium include dementia, age, visual impairment, functional impairment and increased comorbidities. While most studies measuring effect of propofol on sleep disturbance and PD have focussed on the critical care setting, light propofol sedation (to target a bispectral index (BIS) >80) decreased the prevalence of PD by 50% compared to deep sedation (BIS target of 50) in patients undergoing hip surgery with spinal anaesthesia. A further RCT investigated whether limiting propofol sedation with spinal anaesthesia in non-elective hip fracture repair patients reduced risk of delirium post-operatively. Patients were randomised to receive either heavier sedation (modified observer's assessment of alertness/sedation score (OAA/S) of 0-2) or lighter sedation (OAA/S of 4-5). There were no significant differences in risk of incident delirium between the heavier and lighter sedation groups. However, when stratified by Charlson comorbidity index (CCI), in low comorbid states, heavier sedation levels doubled the risk of delirium compared to lighter sedation. This randomised controlled trial (RCT) recruited hip fracture patients with a mean age of 82 years. Therefore, a similar study should be conducted in younger, less comorbid patients undergoing elective joint arthroplasty.

Sedation can also affect recovery following surgery. Being male, nausea, vomiting and pain during the ward stay have been reported to be risk factors for poor quality of recovery after sedation with midazolam for lower limb orthopaedic surgeries. Poor quality of recovery following surgery can also increase hospital stay and health care resources. No significant difference in quality of recovery has been reported between those who experienced immersive VR and those who underwent conventional care.

Propofol infusions are commonly administered alongside spinal anaesthesia for orthopaedic surgery. It is commonly given with no specific objective clinical target end point. This gives rise to the potential of administering excess propofol which may result in inadvertent deep levels of sedation. This can cause prolonged periods of inadvertent general anaesthesia depth during 'regional' cases (often without insertion of an airway device). Therefore, it is important to investigate potential ways of lowering propofol infusions during surgery, without increasing patient risk, anxiety or pain, such as through the use of VR.

Aims of Study

The aims of this pilot study are to determine:

1. the feasibility of using VR during TKA with spinal anaesthesia.
2. what outcomes, if any, can be influenced using VR during TKA with spinal anaesthesia.

Inclusion Criteria:

• Patients ≥ 18 years old who are American Society of Anaesthesiologists (ASA) grade 1 or 2 scheduled for routine primary elective knee arthroplasty.

Exclusion Criteria:

• Patients who are ASA grade 3 or 4.
• Patients who cannot use VR e.g. those with dementia.
• Patients with an existing diagnosis of delirium.
• Patients with visual impairment if degree of myopia/hyperopia exceeds the corrective power of the VR headset.
• Patients with hearing aids.
• Patients with previous history of motion sickness.
• Patients with epilepsy, history of black outs or fitting.
• Patients who will have an operation over 1 hour in duration or any patient who requires more complex surgery.
• Patients who have requested no sedation during the operation.
• Patients who have received premedication.
• Patients who have a general anaesthetic.
• Patients who do not adequately understand verbal explanations or written information given in English, or who have special communication needs.
• Patients who are not capable of informed consent.