Introduction

As the scope of ambulatory surgery continues to expand, more complex procedures, on sicker patients and those belonging to the extremes of age are being performed. In order to ensure patient safety and to administer a complication free anaesthetic, it is important to have stringent selection of patients and well established discharge criteria. Ideally, ambulatory anaesthesia should permit rapid recovery with minimal or no residual cognitive or psychomotor impairment. At discharge, patients must be clinically stable and able to rest at home under the care of a responsible adult. Clinical criteria are generally used to guide discharge, but as the nature of surgery and the patients co-morbidities become complex, the timing of discharge also becomes crucial. A negligible readmission rate is essential to the success of any day care facility.

Stages of Recovery

The process of recovery is a continuous one, beginning from the cessation of anaesthetic to the return of the patient to his preoperative physiological state. The entire process may take hours to days, depending on the anaesthetic drugs used. Recovery has been traditionally divided into three phases.

Phase I: This includes the period from cessation of anaesthetic, to the time the patient regains protective reflexes and motor function. This is a crucial time and patients need close supervision. Phase I recovery occurs in the Post Anaesthesia Care Unit (PACU) under vigilant monitoring. The Aldrete score was designed in 1970 to assess early recovery. The score assigns a score of 0, 1, and 2 each to activity, respiration, circulation, consciousness and colour. The modified Aldrete score which includes pulse oximetry to assess oxygenation is commonly used to judge the adequacy of Phase I recovery and the transfer to a step down unit or an ambulatory surgical unit (ASU). A score greater than 9 is required for discharge from PACU. A limitation of the Aldrete score
is that it does not assess nausea, vomiting and pain.

Fast tracking: The availability of ultra short acting anaesthetic agents and cerebral function monitors e.g. Bispectral Index, which permits titration of agents to the depth of anaesthesia, has resulted in faster recovery time. Phase I recovery can now be completed in the OR itself, permitting direct transfer of patients to the step down unit. This bypassing of the PACU, has been called “fast tracking”. Substantial cost savings can result from bypassing the PACU which mandates a high nurse – patient ratio.

Phase II/ Intermediate recovery: This is the period of stay in the ASU or step down unit until the patient is fit to be discharged home. There are several tests to assess intermediate recovery including Trieger dot test, Maddox wing test, reaction time tests, use of driving simulators etc. The drawbacks with these tests are that they are complex and time consuming, and they require special equipment that may not be readily available. Also, these tests, as a guide to discharging patients, have a major failing in that the patient may be in pain or have nausea or vomiting. Clinical criteria, therefore, continue to be popular in deciding discharge.

Korttila et al developed criteria for safe discharge following ambulatory surgery.

Guidelines for Safe Discharge after Ambulatory Surgery

Vital signs must have been stable for at least 1 h

The patient must be
Oriented to person, place, and time
Able to retain orally administered fluids
Able to void
Able to dress
Able to walk without assistance

Regional anesthesia is popular in the ambulatory setting because it confers the benefits of better pain control, less nausea and vomiting, and shorter lengths of stay in the PACU. Discharge times from the ASU however, seems similar to general anaesthesia techniques. Before allowing patients to ambulate after spinal anesthesia, it is important to ensure that the motor, sensory, and sympathetic blocks have regressed. Suitable criteria to judge block regression include normal perianal (S4–5) sensation, plantar flexion of the foot, and proprioception in the big toe. For peripheral nerve blocks, it maybe acceptable to discharge patients home before full regression of motor and sensory block provided explicit instructions are given regarding care of the insensate limb.
Complications after ambulatory surgery
Postoperative complications can lead to delays in discharge, admission and readmissions. Re admission rate is an important outcome measure for a day care facility.
Postoperative pain
Strong predictors for post operative pain are orthopaedic and urologic surgery and long duration of surgery. Postoperative analgesia combining intraoperative opiates, local anesthesia, and NSAIDs, referred to as either balanced or multimodal analgesia, can lead to significantly shorter discharge times, lower pain scores, and a lower incidence of nausea and vomiting, compared with traditional opiate-based anesthetic techniques
Nausea and Vomiting are common complaints which can delay discharge. Risk factors for the development of PONV are female gender, history of PONV or motion sickness, nonsmoking status, and use of postoperative opioids. Additional important predictors include surgery duration > 60 min, major and laparoscopic gynecological surgery, intra-abdominal surgery, and middle-ear surgery.
Modifications in the anaesthesia technique can reduce the incidence of PONV. Use of Propofol, prophylactic anti emetics e.g. 5HT3 antagonist Ondansetron in high risk groups is advocated.Gastric distension after mask ventilation can precipitate PONV. Gastric decompression may benefit. Use of Neostigmine may be associated with an increased incidence of PONV when used as a reversal drug because of its gastrointestinal effects. The rapid recovery characteristic of Mivacurium makes reversal drugs unnecessary and allows Neostigmine to be eliminated from the anesthetic technique. The opioid analgesics have a powerful emetic action, and one effective method of reducing the incidence of PONV is to minimize their use.

Less Common Postoperative Complications include sore throat, headache, dizziness, and drowsiness. Perioperative dehydration seems to aggravate the symptoms.Administering 20 mL/kg (versus 2 mL/kg) of saline IV can reduce the incidence of thirst, dizziness, and drowsiness for up to 24 hours postoperatively. Occurrence of post spinal headache can be minimized by use of pencil point needles or fine gauge Quinke needles. Risk factors for sore throat include endotracheal anesthesia compared with anesthesia provided by a laryngeal mask airway, female sex, younger patients, use of succinylcholine, and gynecological surgery.

Various scoring systems have been devised to guide the process of discharge and home-readiness, to ensure patient safety. To avoid inappropriate or premature discharge, the anesthesiologist must ensure that the patient is “street fit” prior to discharge, that there is appropriate documentation of recovery, and that specified discharge criteria are met.
Another factor that influences discharge is the surgeon’s skill and the number of outpatient procedures he/she performs in a given year. Patients having operations by “low-volume” surgeons tend to have an extended length of stay when compared with outcomes of “high-volume” surgeons.

Unanticipated hospital admission

Unanticipated hospital admission is defined as the admission of patients scheduled for ambulatory surgery due to unforeseen problems such as surgical and anesthetic complications. The commonest causes are: surgical factors (pain, extensive surgery, bleeding), anesthetic factors (PONV and anesthesia-related complications), social, and medical factors .

Otorhinolaryngology, urology and general surgery account for the top three types of surgery admitted to hospital. The predictive factors are male patients, age > 50 years, ASA physical status III, surgical time greater than 60 min (fourfold increased risk of admission), postoperative bleeding, excessive pain, nausea and vomiting, and excessive drowsiness or dizziness.
In association with ambulatory surgery, hospital re-admission is defined as an ambulatory surgical patient requiring inpatient admission following discharge from an ASU due to complications.
Patients undergoing urologic procedures such as transurethral resection of bladder tumour, varicocelectomy and hydrocelectomy, are more likely to return to hospital. The leading causes of readmission to hospital related to these procedures are bleeding and surgical complications. Other causes are pain, urinary retention and infection. Age > 85 years, previous inpatient hospital admission within six months, and invasiveness of surgery are the risk factors identified.General surgery, ENT and urology are the specialties associated with the highest readmission rate.
Appropriate selection of patients can reduce the complication rate. It may be prudent for a day care facility to select patients with ASA status I, II or III if the disease is well controlled. Although there are no age limits specified, expremature babies, low birth weight and smallfor gestational age infants until six months of age may be excluded. The surgery should be of a short duration
(1-2 hours), with minimal haemorrhage and postoperative pain. Requirements for post discharge nursing must be minimal. Equally important is the competency of the surgeon and the anaesthesiologist which should guide selection criteria.
Finally, obtaining patient feedback provides valuable insight into the quality of services. Studies reveal that outpatients tend to value highest those elements of care representing information and communication.Written information regarding the complications of anaesthesia and surgery and instructions pertaining to post operative care should be made available to the patient. Scoring systems guide transfer of patients from the OR to the PACU and determine fitness for discharge. A practical, easy to use scoring system applicable to all post anaesthesia situations should be adopted by every day care facility.
References

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3. Marshall S I, Chung F. Discharge Criteria and Complications after Ambulatory Surgery. Anesth Analg
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