Anaesthesia and Chronic Pain

Ambulatory Anaesthesia

JN Monteiro

Definition
An ambulatory anaesthesia is one
administered for a non emergency/elective surgical procedure, performed on carefully selected patients, which is undertaken with all its constituent elements (admission, operation and discharge home) on the same day. It is also referred to as day case anaesthesia, day care anaesthesia, outpatient anaesthesia and more recently office based anaesthesia.

Introduction
Ambulatory anaesthesia is a relatively young and rapidly growing subspeciality. Although its history is as old as the history of general anaesthesia itself it has emerged as a recognized concept and is evolving over the past couple of decades. In US it comprises at current estimates 70% of anaesthesia services provided. In the UK it is referred to as “day case anaesthesia” and the NHS Plan, published recently predicts that 75% of elective surgical procedures will soon be conducted as day cases. In our institute 70% of elective surgeries that qualify the criteria are performed as day cases.

Emergence
The justification has been consistent since the early 1950’s. The advantages of lower cost, lower rate of infection, less patient anxiety and greater patient convenience have been demonstrated. It was established paediatric patients recovered better at home without separating from their mothers, patients saved money by recovering at home continued to be employed while recuperating, thus beds were free for the hospital for sicker patients.
Newer anaesthetics allow patients to recover faster, permitting the number and the complexity of cases to include longer and more complex procedures permitting a safer operation theatre without flammable anaesthetics. Processes were developed for moving through the different stages of a surgical procedure and to transition and then safely home. Technology has developed monitors to monitor patients more carefully during anesthesia thus permitting sicker patients with more challenging medical conditions to be considered for ambulatory anaesthesia.
Great societal and economic pressures developed. Hospitals struggled to meet the demand for inpatient beds and day case anaesthesia provided relief. It was quickly discovered that outpatient surgery could save on surgical lists and as a result it was recommended by insurers and society as a quick solution to curb medical costs this was the final force that drove the emergence and growth of the subspecialty.

Preoperative Evaluation
All patients listed for day surgery, attend a preassessment clinic ideally as soon as the decision to operate is made. This ensures that patients listed for the procedure fit the agreed medical selection criteria. This consult provides an opportunity for explanation and discussion, helping to inform the patient and allaying anxieties. Preoperative testing should be performed only if specifically indicated by the history or examination and if an abnormal test would alter patient management. Those requiring further investigations, anaesthetic assessment or their treatment to be optimized are identified early and corrective action taken. Preoperative fasting guidelines, factors that may improve the outcome of the procedure like stopping smoking or weight reduction may also be discussed.

Agents
Anaesthetic agents today have been designed and marketed to meet specific niche criteria for ambulatory anesthesia. Among the agents available in India Propofol, Sevoflurane have increased the ability of the anaesthesiologist to provide a successful day case experience. Because of the rapid onset and offset of these agents longer cases can be planned on an ambulatory basis and patients can recover quickly and can be discharged home safely. Side effects such as the “hang-over effect” can be minimized. Propofol has the additional effect of reducing PONV (post operative nausea and vomiting). There are several intermediate acting muscle relaxants available due to advancements in muscle relaxant that are perfectly suited to majority of cases requiring muscle relaxation. Devices for airway management have also progressed. The emergence of the LMA (laryngeal mask airway) and COPA (cuffed oropharyngeal airway) significantly broadened the options in the airway management armamentarium. A patient suitable for LMA instead of endotracheal intubation is no longer exposed to muscle relaxants for the sake of maintaining the airway. Short acting drugs provide great advantages for speed of emergence and potential cost savings but they are expensive. Few studies have been done that actually examine the actual cost to society of the various choices in ambulatory anaesthesia.

Techniques
The challenging objectives and the growing importance of ambulatory anaesthesia has led to a development of efficient, safe, and fast tracked general anaesthetic technique TIVA (Total intravenous anaesthesia) of which ultra-short acting intravenous agents have played an important role. Though intravenous induction or inhalational induction are both suitable in the ambulatory setting maintenance of general anaesthesia with inhalational agents may be more cost effective. Newer available agents are expensive and in skilled hands older less expensive agents can also provide a comparable anaesthetic.
Regional techniques offer significant advantages in the outpatient setting. They can avoid the side effects of nausea, vomiting and pain that frequently delay discharge or cause admission. They can also provide prolonged analgesia and with the use of continuous catheter infusions a pain free perioperative period. The choice of drugs must be well adjusted with the neuraxial technique. Despite frequently requiring some additional time at the outset, regional techniques have consistently been shown to provide competitive discharge times and costs when compared with general anaesthesia. They deserve a prominent place in day case surgery.

Recovery
The recovery begins immediately at the end of anaesthesia and can be divided into three definite phases.
Early phase: the patient emerges from the anaesthesia and is closely monitored.
Intermediate phase: the patient has emerged completely from the anaesthesia and is assessed for discharge.
Late recovery phase: the patient recovers completely from surgery and anaesthesia and resumes normal daily activities.
There are a number of scoring systems to assess readiness for discharge these use a variety of parameters such as level of consciousness, breathing, circulation, activity level, complications and mobility besides these scoring systems number of guidelines have been developed. It is also important to consider the patient's mental state when discharge is considered. They should feel ready to go home. Discharging the patient against their wishes could have serious consequences.

Postoperative analgesia
The control of pain is crucial for the provision of good day case anaesthesia. There must be good communication between the patient and anaesthetist to increase compliance with the prescribed medication and ensure the patient’s expectations are realistic. Good postoperative analgesia requires planning and a proactive approach. Treatment can be started preoperatively with the administration of paracetamol and NSAIDs (non-steroidal anti-inflammatory drugs). There is a trend away from opioid analgesics as they are associated with PONV (post operative nausea and vomiting) that results in patient dissatisfaction and delays discharge. A multimodal approach including regional anaesthetic techniques as well as oral / parenteral analgesics has a higher success.

Conclusion
New technology, surgical techniques, and progress in anaesthesiology will be supported and financed by society as long as it reduces the cost of health care. Although new technology may increase the direct costs of providing care in the operating room, the overall costs to society should be decreased by a decrease in lost productivity and individual suffering on the part of the patients. It would be prudent for the anaesthesiologist to remain committed to the safety and the comfort of the patient primarily thus ensuring the future of the subspecialty will continue to remain bright..