Introduction
The concept of ambulatory procedure with admission, operation, and discharge on the same day has evolved considerably over the last two decades. The number of ambulatory surgical procedures has grown tremendously throughout the world. The rapid growth of ambulatory surgical care worldwide is attributed to its multiple advantages, such as early return to preoperative physiologic state, fewer complications, reduced physical and mental disturbance, early resumption of normal activities, and reduced hospital costs. The major advance in anesthetic techniques includes the use of rapidly dissipated anesthetic agents and the increasing use of regional anesthetic techniques. It is expected that the number, diversity, and complexity of operations performed in the outpatient setting will continue to increase.
Time to discharge from an ambulatory surgical unit is considered to be a measure of the efficiency of the unit. Counterbalancing efficiency, patient safety is also an important issue in terms of a good practice. Hence, for a successful ambulatory surgical unit, emphasis is not only on patient selection but also on scientifically sound and safe discharge criteria. This chapter outlines the current literature available on discharge criteria and reviews the factors affecting the discharge.
Evidence
The knowledge regarding the process of recovery and the concept of fast-tracking are essential in understanding the application of the appropriate discharge criteria that are presently available. Recovery is an ongoing process that begins from the end of intraoperative care until the patient returns to his or her preoperative physiologic state. This process is divided into three distinct phases: early, intermediate, and late recovery. Early recovery (phase 1) is from the discontinuation of anesthetic agents to the recovery of the protective reflexes and motor function. At most institutions, the phase 1 recovery occurs in the postanesthesia care unit (PACU).
Intermediate recovery (phase 2) occurs when the patient achieves criteria for discharge from the PACU and occurs mostly in the step-down or ambulatory surgical unit (ASU). Late recovery (phase 3) continues at home under the supervision of a responsible adult and continues until the patient returns to his or her preoperative physiologic state.
Traditionally, most patients are transferred from the operating room to the PACU and then to the ASU before they are discharged home. However, the recovery care after ambulatory surgery is now in a state of change with advances in surgical and anesthetic techniques. This has facilitated an early recovery process. It is now possible to have patients who are awake, alert, and comfortable in the operating room to bypass the labor-intensive PACU directly into the step 2 recovery area. This new concept is referred as fast-tracking in ambulatory surgery.
Discharge Criteria
The many discharge criteria commonly employed are identified in Box 45-1 . There are discharge criteria for the PACU, the ASU, and fast-tracking.
Discharge Criteria Applied at Different Phases of Recovery
Discharge criteria at postanesthesia care unit (phase 1 recovery)
Aldrete score
Discharge criteria at ambulatory surgical unit (phase 2 recovery)
Postanesthesia discharge score
Outcome-based discharge criteria
Discharge criteria for fast-tracking
White fast-tracking score
Discharge Criteria used for Research Purposes
Psychomotor test of recovery (phase 3 recovery)
Discharge Criteria used Under Specific Circumstances
Discharge home criteria after neuraxial blockade
Discharge home criteria after peripheral nerve block
Discharge home criteria for suspected malignant hyperthermia
Discharge Criteria for the Postanesthesia Care Unit
The Aldrete score has been successful in addressing the early phase 1 recovery. This score, created in 1970, is a modification of the Apgar score used in neonates. This score assesses five parameters: respiration, circulation, consciousness, color, and level of activity. Each parameter is scored 0, 1, or 2, and patients scoring 9 or greater are eligible to be transferred from the high-dependency PACU to the ASU. However, with the advent of pulse oximetry, the Aldrete score was modified in 1995 to include this technologic improvement ( Table 45-1 ).
| Discharge Criteria from Postanesthesia Care Unit | Score | |
|---|---|---|
| Activity | Able to move voluntarily or on command | |
| Four extremities | 2 | |
| Two extremities | 1 | |
| Zero extremities | 0 | |
| Respiration | Able to breathe and cough freely | 2 |
| Dyspnea, shallow or limited breathing | 1 | |
| Apneic | 0 | |
| Circulation | Blood pressure 20 mm of preanesthetic level | 2 |
| Blood pressure 20-50 mm of preanesthesia level | 1 | |
| Blood pressure −50 mm of preanesthesia level | 0 | |
| Consciousness | Fully awake | 2 |
| Arousable on calling | 1 | |
| Not responding | 0 | |
| O 2 saturation | Able to maintain O 2 saturation >92% on room air | 2 |
| Needs O 2 inhalation to maintain O 2 saturation >90% | 1 | |
| O 2 saturation <90% even with O 2 supplementation | 0 |
* To determine readiness for discharge from postanesthesia care unit. A score >9 is required for discharge.
Although the Aldrete score is an effective screening tool, it has a few limitations. It does not provide an assessment for home-readiness, and it does not address some of the common side effects seen in the PACU, such as pain, nausea and vomiting, and bleeding at the incision site.
Discharge Criteria for the Ambulatory Surgical Unit
Discharge criteria applied in the ASU are designed to assess home-readiness of patients, and hence strict adherence to the criteria to ensure patient safety is important. There are a number of available criteria, but the most common criteria that are applied at the ASU are the safe discharge criteria proposed by Korttila and the postanesthesia discharge score (PADS) devised by Chung and colleagues.
The safe discharge criteria use outcome-based clinical observations, and all parameters have to be met before discharge. It is important to note that clinical observations such as the need to drink and void before discharge, which were initial prerequisites in “safe discharge criteria,” are no longer applicable. Current outcome-based discharge criteria are listed in Box 45-2 .
* A set of typical discharge criteria to determine readiness for discharge from postanesthesia care unit. All parameters of safe discharge criteria need to be met before discharge.
- •
Patient alert and oriented to time, place, and person
- •
Stable vital signs
- •
Pain controlled by oral analgesics
- •
Nausea and emesis controlled
- •
Able to walk without dizziness
- •
No unexpected bleeding from the operating sites
- •
Discharge instruction and prescription received
- •
Patient accepts readiness for discharge
- •
Responsible escort
Chung and colleagues devised the PADS in 1993. The PADS was later modified to eliminate the requirements for oral fluid intake and urinary output before discharge. It has been demonstrated that the implementation of PADS as a criterion for discharge from the ASU facilitates expeditious discharge, with 80% of patients able to be discharged within 1 to 2 hours. PADS is a cumulative index that measures the home-readiness of patients based on five major criteria: (1) vital signs, (2) ambulation, (3) pain, (4) postoperative nausea and vomiting, and (5) surgical bleeding. The pain criteria have been further refined to score pain with a visual analog scale ranging from 1 to 10 ( Table 45-2 ). Patients who achieve a score of 9 or greater are considered fit for discharge with an adult escort. PADS also provides for an objective determination of the optimal length of patient stay following ambulatory surgery (see Table 45-2 ).
| Vital Signs | |
| Within 20% of preoperative baseline | 2 |
| 20%-40% of preoperative baseline | 1 |
| 40% of preoperative baseline | 0 |
| Activity Level | |
| Steady gait, no dizziness, consistent with preoperative level | 2 |
| Requires assistance | 1 |
| Unable to ambulate/assess | 0 |
| Nausea and Vomiting | |
| Minimal: mild, no treatment required | 2 |
| Moderate: treatment effective | 1 |
| Severe: treatment not effective | 0 |
| Pain | |
| VAS = 0-3: the patient has minimal or no pain before discharge | 2 |
| VAS = 4-6: the patient has moderate pain | 1 |
| VAS = 7-10: the patient has severe pain | 0 |
| Surgical Bleeding | |
| Minimal: does not require dressing change | 2 |
| Moderate: required up to two dressing changes with no further bleeding | 1 |
| Severe: required three or more dressing changes and continues to bleed | 0 |
Discharge Criteria for Fast-Tracking
The success of fast-tracking depends on the appropriate modification of anesthetic technique, which would allow rapid emergence from anesthesia and the prevention of common postoperative complications such as pain, nausea, and vomiting using a multimodal approach. White and Song devised a fast-tracking score, which incorporated assessment of pain and emetic symptoms, to the original Aldrete score. The maximum possible score is 14. A score of 12 (with no score less than 1 in any category) is considered sufficient for discharge from the operating room to the ASU ( Table 45-3 ).
| Discharge Criteria | Score |
|---|---|
| Level of Consciousness | |
| Awake and oriented | 2 |
| Arousable with minimal stimulation | 1 |
| Responsive to tactile stimulation | 0 |
| Physical Activity | |
| Able to move all extremities on command | 2 |
| Some weakness in movement of extremities | 1 |
| Unable to voluntarily move extremities | 0 |
| Hemodynamic Stability | |
| Blood pressure <15% of baseline MAP value | 2 |
| Blood pressure 15%-30% of baseline MAP value | 1 |
| Blood pressure >30% below the baseline MAP value | 0 |
| Respiratory Stability | |
| Able to breathe deeply | 2 |
| Tachypnea with good cough | 1 |
| Dyspneic with good cough | 0 |
| Oxygen Saturation Status | |
| Maintains value >90% on room air | 2 |
| Requires supplemental oxygen | 1 |
| Saturation <90% with supplemental oxygen | 0 |
| Postoperative Pain Assessment | |
| None, or mild discomfort | 2 |
| Moderate to severe pain controlled with intravenous analgesics | 1 |
| Persistent severe pain | 0 |
| Postoperative Emetic Symptoms | |
| None, or mild nausea with no active vomiting | 2 |
| Transient vomiting | 1 |
| Persistent moderate to severe nausea and vomiting | 0 |
| Total possible score | 14 |
Studies have shown that outpatients who are fast-tracked can be discharged earlier without any increase in complications or side effects. Apfelbaum and colleagues undertook a multicenter prospective study to determine the safe bypass of PACU by patients after ambulatory surgery. After education of the health personnel, the PACU bypass rate of patients having general anesthesia increased from 15.9% at baseline to 58%. These patients had a significantly shorter duration of recovery when compared with patients who had a standard recovery at the PACU.
However, the advantages of a faster recovery and saving time may not reflect the true nursing workload and real cost savings. A recent randomized control trial compared fast-tracking of bypassing PACU with no bypassing of PACU. In this study, patients were randomly assigned to either a routine or a fast-tracking group. Patients in the fast-tracking group were transferred from the operating room directly to the ASU (i.e., bypassing the PACU) if they achieved the fast-tracking criteria. All other patients were transferred to the PACU and then to the ASU. The mean time to discharge was 17 minutes less in the fast-tracking group, but the overall nursing workload and the associated cost were not significantly different between the two groups.
A number of psychomotor tests are available ( Table 45-4 ) to determine recovery of patients; however, the tests have a number of disadvantages. They require equipment and trained personnel to use and interpret the equipment. The tests are time consuming and usually only assess one area of brain function. Therefore they are mostly used for research purposes rather than for clinical use.
| Test | Description |
|---|---|
| Simple reaction time | Time to press a keyboard in response to a stimulus (e.g., buzzer) |
| Choice reaction time | Involves choice of optical stimulus (e.g., green/red) |
| Critical flicker fusion time | Involves the time it takes for the patient to notice a flickering light at a particular frequency that appears and becomes continuous |
| Digital symbol substitution test | |
| Perceptive accuracy test | |
| Digital span | The ability to recall strings of numbers |
| California verbal test | Ability to remember a list of words from a previously presented list |
| Trieger dot test (Gestalt test) | Ability to connect a series of dots on paper to form a pattern; the more dots the patient misses, the lower the recovery score |
| Driving simulation test | |
| Maddox wing test | A device to test extraocular muscle balance |
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