Key Concepts
Formerly anesthetized patients should not leave the operating room unless they have a patent airway, have adequate ventilation and oxygenation, and are hemodynamically stable; qualified anesthesia personnel must also be available to attend the transfer.
Before the recovering patient is fully responsive, pain is often manifested as postoperative restlessness. Serious systemic disturbances (eg, hypoxemia, respiratory or metabolic acidosis, or hypotension), bladder distention, or a surgical complication (eg, occult intraabdominal hemorrhage) must also be considered in the differential diagnosis of postoperative agitation.
Intense shivering causes precipitous rises in oxygen consumption, CO2 production, and cardiac output. These physiological effects are often poorly tolerated by patients with preexisting cardiac or pulmonary impairment.
Respiratory problems are the most frequently encountered serious complications in the postanesthesia care unit (PACU). The overwhelming majority are related to airway obstruction, hypoventilation, and/or hypoxemia.
Hypoventilation in the PACU is most commonly due to the residual depressant effects of anesthetic agents on respiratory drive.
Obtundation, circulatory depression, or severe acidosis (arterial blood pH < 7.15) is an indication for immediate and aggressive respiratory and hemodynamic intervention, including airway and inotropic support as needed.
Following naloxone administration, patients should be observed closely for recurrence of opioid-induced respiratory depression (“renarcotization”), as naloxone has a shorter duration than do most opioids.
Increased intrapulmonary shunting from a decreased functional residual capacity relative to closing capacity is the most common cause of hypoxemia following general anesthesia.
The possibility of a postoperative pneumothorax should always be considered following central line placement, intercostal blocks, abdominal or chest trauma (including rib fractures), neck dissections, tracheostomy, nephrectomies, or other retroperitoneal or intraabdominal procedures (including laparoscopy), especially if the diaphragm may have been penetrated or disrupted.
Hypovolemia is by far the most common cause of hypotension in the PACU.
Noxious stimulation from incisional pain, endotracheal intubation, or bladder distention is usually responsible for postoperative hypertension.
Postanesthesia Care: Introduction
Historically, emphasis on specialized nursing care during the immediate postoperative period was prompted by the realization that many early postoperative deaths occurred immediately after anesthesia and surgery and that many of these deaths were preventable. A nursing shortage in the United States following World War II, as well as the experience of providing surgical care to large numbers of battle casualties during the war, contributed to the postwar trend of centralization of immediate postoperative care in the form of recovery rooms, where one or more nurses could pay close attention to several acute postoperative patients at one time. Over the past two decades, the accelerating practice of caring for selected postoperative patients overnight in a postanesthesia care unit (PACU), or the equivalent, has been a response to increasingly complex surgical procedures performed on higher-acuity patients, often in the setting of a shortage of surgical intensive care beds. The success of PACUs in decreasing postoperative morbidity and mortality has been a major influence on the evolution of modern surgical intensive care units.
Another recent transformation in postanesthesia care is related to the shift from inpatient to outpatient surgery. It is estimated that more than 70% of all surgical procedures in the United States are now performed on an outpatient basis. Two phases of recovery may be recognized for outpatient surgery. Phase 1 is the immediate intensive care level recovery that cares for patients during emergence and awakening from anesthesia and continues until standard PACU criteria are met (see Discharge Criteria below). Phase 2 is a lower-level care that ensures that the patient is ready to go home. “Fast-tracking” of selected outpatients may allow them to safely bypass phase 1 recovery and go directly to the phase 2 level of care.
In many institutions, the PACU also commonly functions as a more intensely monitored location for perioperative and chronic pain patients undergoing procedures such as single-shot nerve blocks and placement of epidural and peripheral nerve catheters, and for patients undergoing other procedures such as central line placement, electroconvulsive therapy, and elective cardioversion. The PACU must be appropriately staffed and equipped to routinely manage these patients and their potential procedure-related complications. For example, in areas where regional and epidural blocks are administered, Intralipid® should be stocked in anticipation of treating local anesthetic toxicity.
This chapter discusses the essential components of a modern PACU, the general care of patients acutely recovering from anesthesia and surgery, and the respiratory and circulatory complications most commonly encountered in the PACU.
At the conclusion of any procedure requiring anesthesia, anesthetic agents are discontinued, monitors are disconnected, and the patient emerging from sedation or anesthesia is taken to the PACU. Following general anesthesia, if an endotracheal tube or laryngeal mask airway (LMA) was utilized, and if ventilation is judged adequate, the endotracheal tube or LMA is usually removed prior to transport. Patients are also routinely observed in the PACU following regional anesthesia and monitored anesthesia care (local anesthesia with sedation). Most procedure guidelines require that a patient be admitted to the PACU following any type of anesthesia, except by specific order of the attending anesthesiologist. After a brief verbal (and in some cases written) “hand off” report to the PACU nurse, the patient is left in the PACU until the major effects of anesthesia have worn off. This period is characterized by a relatively high incidence of potentially life-threatening respiratory and circulatory complications.
The delivery of anesthesia services in areas remote from the main operating room, such as endoscopy, interventional radiology, and magnetic resonance imaging suites is increasingly common. Patients recovering from anesthesia delivered in these areas must receive the same standard of care as patients recovering from anesthesia received in the main operating room. Some institutions have developed “satellite” PACUs to serve each of these remote areas individually, and others have combined their procedural areas into one centralized procedural suite served by a single PACU.
The PACU should be located near the operating rooms and off-site invasive procedure areas. A central location in the operating room area itself is desirable, as it ensures that the patient can be rushed back to surgery, if needed, or that members of the operating room team can quickly respond to urgent or emergent patient care issues. Proximity to radiographic, laboratory, and other intensive care facilities on the same floor is also advantageous. The transfer of critically ill patients in elevators or through long corridors can jeopardize their care because urgent problems may arise along the way.
An open-ward design facilitates observation of multiple patients simultaneously. However, an appropriate number of individually enclosed patient care spaces is required for patients needing isolation for infection control. A ratio of 1.5 PACU beds per operating room is customary, although this number will vary depending on the respective operating room suite’s case volume, variety of surgical procedures, and patient acuity. Each patient space should be well-lighted and large enough to allow easy access to patients in spite of poles for intravenous infusion pumps, a ventilator, or radiographic equipment; construction guidelines dictate a minimum of 7 ft between beds and 120 sq ft/patient. Multiple electrical outlets, including at least one with backup emergency power, and at least one outlet each for oxygen and suction, should be present at each bed space.
Many PACU incidents leading to serious morbidity or mortality are related to inadequate monitoring. Pulse oximetry (Spo2), electrocardiogram (ECG), and automated noninvasive blood pressure (NIBP) monitors are mandatory for each space. Although ECG, Spo2, and NIBP must be utilized for every patient in the initial phase of recovery from anesthesia (phase 1 care), decreased monitoring may be adequate thereafter. Appropriate equipment must be available for those patients requiring invasive arterial, central venous, pulmonary artery, or intracranial pressure monitoring. Capnography is useful for intubated patients and is increasingly employed for extubated patients as well. Temperature-sensitive strips may be used to measure temperature in the PACU but are not sufficiently accurate to document the results of treatment for hypothermia or hyperthermia; mercury or electronic thermometers must be used if an abnormality in temperature is suspected. A forced-air warming device, heating lamp, and/or a warming/cooling blanket should be available.
The PACU must have its own supplies of basic and emergency equipment, separate from that of the operating room, based on the needs of the patient population. This includes airway equipment and supplies, such as oxygen cannulas, a selection of masks, oral and nasal airways, laryngoscopes, endotracheal tubes, LMAs, a cricothyrotomy kit, and self-inflating bags for ventilation. A readily available supply of catheters for vascular cannulation (venous, arterial, central venous) is mandatory. A defibrillation device with transcutaneous pacing capabilities, and an emergency cart with drugs and supplies for advanced life support (see Chapter 55) and infusion pumps, must be present and periodically inspected. Transvenous pacing catheters; pulse generators; and tracheostomy, chest tube, and vascular cut-down trays are typically present, depending on the surgical patient population.
Respiratory therapy equipment for aerosol bronchodilator treatments, continuous positive airway pressure (CPAP), and ventilators should be in close proximity to the recovery room. Immediate availability of a bronchoscope is desirable.
Inadequate staffing is often cited as a major contributing factor in PACU mishaps. The PACU should be staffed by nurses specifically trained in the care of adult and/or pediatric patients emerging from anesthesia. They should have expertise in airway management and advanced cardiac life support, as well as problems commonly encountered in surgical patients relating to wound care, drainage catheters, and postoperative bleeding.
Patients in the PACU should be under the medical direction of an anesthesiologist, who must be immediately available to respond to urgent or emergent patient care problems. High-volume tertiary care surgical institutions often have an anesthesiologist assigned full time to the PACU. The management of the patient in the PACU should reflect a coordinated effort involving anesthesiologists, surgeons, nurses, respiratory therapists, and appropriate consultants. The anesthesia team emphasizes management of analgesia, airway, cardiac, pulmonary, and metabolic problems, whereas the surgical team generally manages any problems directly related to the surgical procedure itself. Based on the assumptions that the average PACU stay is 1 hr and that the average inpatient procedure lasts 2-3 hr, a ratio of one recovery nurse for two patients is generally satisfactory. However, staffing for nursing care should be tailored to the unique caseload requirements of each facility. If the operating room schedule regularly includes pediatric patients or frequent short procedures, a ratio of one nurse to one patient is often needed. A charge nurse should be assigned to ensure optimal staffing at all times, including the appropriate response to urgent or emergent patient care problems.
Care of the Patient
Recovery from general or regional anesthesia is a time of great physiological stress. Emergence from general anesthesia should ideally be characterized by a smooth and gradual awakening in a controlled environment. However, problems such as airway obstruction, shivering, agitation, delirium, pain, nausea and vomiting, hypothermia, and autonomic lability are frequently encountered. Patients receiving spinal or epidural anesthesia may experience decreases in blood pressure during transport or recovery; the sympatholytic effects of major conduction blocks prevent compensatory reflex vasoconstriction when patients are moved or when they sit up.
Following an inhalational-based anesthetic, the speed of emergence is directly proportional to alveolar ventilation, but inversely proportional to the agent’s blood solubility (see Chapter 8). As the duration of anesthesia increases, emergence also becomes increasingly dependent on total tissue uptake, which is a function of agent solubility, the average concentration used, and the duration of exposure to the anesthetic. Hypoventilation delays emergence from inhalational anesthesia.
Emergence from an intravenous anesthetic is a function of its pharmacokinetics. Recovery from most intravenous anesthetic agents is dependent primarily on redistribution rather than metabolism and elimination. As the total administered dose increases, however, cumulative effects become clinically apparent in the form of prolonged emergence; the termination of action becomes increasingly dependent on the metabolism or elimination. This is the basis for the concept of a context-sensitive half-time (see Chapter 7). Advanced age or renal or hepatic disease can prolong emergence (see Chapter 9). Short and ultrashort-acting anesthetic agents, such as propofol and remifentanil, significantly shorten emergence, time to awakening, and discharge. Some studies show that the use of a Bispectral Index Scale (BIS) monitor (see Chapter 6) may reduce total drug dosage and shorten recovery and time to discharge. LMA (rather than an endotracheal tube) use may also allow lighter levels of anesthesia that could speed emergence.
The speed of emergence can also be influenced by preoperative medications. Premedication with agents that outlast the procedure (eg, lorazepam) may be expected to prolong emergence. The short duration of action of midazolam makes it a suitable premedication agent for short procedures. The effects of preoperative sleep deprivation or drug ingestion (alcohol, sedatives) can also be additive to those of anesthetic agents and can prolong emergence.
The most frequent cause of delayed emergence (when the patient fails to regain consciousness 30-60 min after general anesthesia) is residual anesthetic, sedative, and analgesic drug effect. Delayed emergence may occur as a result of absolute or relative drug overdose or potentiation of anesthetic agents by prior drug or alcohol ingestion. Naloxone (in 80 mcg increments in adults) and flumazenil (in 0.2 mg increments in adults) will readily reverse the effects of an opioid and benzodiazepine, respectively. Physostigmine (1-2 mg) may partially reverse the effect of other agents. A nerve stimulator can be used to exclude persisting neuromuscular blockade in poorly responsive patients on a mechanical ventilator who have inadequate spontaneous tidal volumes.
Less common causes of delayed emergence include hypothermia, marked metabolic disturbances, and perioperative stroke. A core temperature of less than 33°C has an anesthetic effect and greatly potentiates the actions of central nervous system depressants. Forced-air warming devices are most effective in raising body temperature. Hypoxemia and hypercarbia are readily excluded by pulse oximetry, capnography, and/or blood gas analysis. Hypercalcemia, hypermagnesemia, hyponatremia, and hypoglycemia and hyperglycemia are rare causes of delayed emergence that require laboratory measurements for diagnosis. Perioperative stroke is rare, except after neurological, cardiac, and cerebrovascular surgery (see Chapter 28); diagnosis is facilitated by neurological evaluation and radiological imaging.
This seemingly short period may be complicated by the lack of adequate monitoring, medication access, or resuscitative equipment. 
Formerly anesthetized patients should not leave the operating room unless they have a patent airway, have adequate ventilation and oxygenation, and are hemodynamically stable; qualified anesthesia personnel must attend the transfer. Supplemental oxygen should be administered during transport to patients at risk of hypoxemia. Some studies suggest that transient hypoxemia (Spo2 <90%) may develop in as many as 30% to 50% of otherwise “normal” patients during transport while breathing room air; supplemental oxygen may therefore be advisable for all transported patients, especially if the PACU is not in immediate proximity to the operating room. Unstable patients should remain intubated and should be transported with a portable monitor (ECG, Spo2, and blood pressure) and a supply of emergency drugs.
All patients should be taken to the PACU on a bed or gurney that can be placed in either the head-down (Trendelenburg) or back-up position. The head-down position is useful for hypovolemic patients, whereas the back-up position is useful for patients with underlying pulmonary dysfunction (see Chapters 20 and 23). Patients at increased risk of vomiting or upper airway bleeding (eg, following tonsillectomy) should be transported in the lateral position. This position also helps prevent airway obstruction and facilitates drainage of secretions.
Airway patency, vital signs, oxygenation, and level of consciousness must be assessed immediately upon PACU arrival. Subsequent blood pressure, heart rate, and respiratory rate measurements are routinely made at least every 5 min for 15 min or until stable, and every 15 min thereafter. Pulse oximetry should be monitored continuously in all patients. The occurrence of hypoxemia does not necessarily correlate with the level of consciousness. Neuromuscular function should be assessed clinically (eg, head-lift and grip strength). At least one temperature measurement must also be obtained. Additional monitoring includes pain assessment (eg, numerical or descriptive scales); the presence or absence of nausea or vomiting; and fluid input and output, including urine flow, drainage, and bleeding. After initial vital signs have been recorded, the anesthesia provider should give a brief report to the PACU nurse that includes (1) the preoperative history (including mental status and any communication problems, such as language barriers, deafness, blindness, or mental disability); (2) pertinent intraoperative events (type of anesthesia, the surgical procedure, blood loss, fluid replacement, antibiotic and other relevant medication administration, and any complications); (3) expected postoperative problems; (4) anticipated need for PACU medication administration, such as antibiotics; and (5) postanesthesia orders (analgesia and nausea/vomiting therapy; epidural or perineural catheter care; including the need for acute pain service involvement, administration of fluids or blood products, postoperative ventilation, chest x-ray for follow-up of central venous catheterization, etc.).
All patients recovering from general anesthesia must receive supplemental oxygen and pulse oximetry monitoring during emergence because transient hypoxemia can develop even in healthy patients. A rational decision regarding continuation of supplemental oxygen therapy at the time of PACU discharge can be made based on Spo2 readings on room air. Arterial blood gas measurements may be obtained to confirm abnormal oximetry readings, but are not necessary in most patients. Oxygen therapy should be carefully controlled in patients with chronic obstructive pulmonary disease and a history of, or potential for, CO2 retention. Patients should generally be nursed in the back-up position, whenever possible, to optimize oxygenation. However, elevating the head of the bed before the patient is responsive can lead to airway obstruction. In such cases, the oral or nasal airway should be left in place until the patient is awake and able to maintain airway. Deep breathing and coughing should be encouraged periodically.
Patients who are heavily sedated or hemodynamically unstable following regional anesthesia should also receive supplemental oxygen in the PACU. Sensory and motor levels should be periodically recorded following regional anesthesia to document regression of the block. Precautions in the form of padding or repeated warning may be necessary to prevent self-injury from uncoordinated arm movements following brachial plexus blocks. Blood pressure should be closely monitored following spinal and epidural anesthesia. Bladder catheterization may be necessary in patients who have had spinal or epidural anesthesia for longer than 4 hr.
Moderate to severe postoperative pain is most commonly treated with oral or parenteral opioids. However, perioperative opioid administration is associated with side effects (nausea and vomiting, respiratory depression, pruritis, ileus, and urinary retention) which may have significant adverse effects on postoperative convalescence. In response to this problem, a variety of opioid sparing strategies have been increasingly embraced over the past two decades to decrease opioid requirements, and thus opioid-related side effects, while maintaining satisfactory analgesia (see Chapter 47). Preoperative oral administration of nonsteroidal antiinflammatory drugs (NSAIDs), acetaminophen, and gabapentin or pregabalin may significantly reduce postoperative opioid requirements, and these medications may be resumed postoperatively if the patient can continue oral medication. Additional analgesic modalities utilizing local anesthetics, such as intraoperative wound infiltration, postoperative wound catheter infusions, single-shot and continuous catheter peripheral nerve blocks, and continuous epidural infusions, also reduce postoperative opioid analgesic requirements, and thus also reduce opioid-related side effects.
Mild to moderate postoperative pain can be treated orally with acetaminophen, ibuprofen, hydrocodone, or oxycodone. Alternatively, ketorolac tromethamine (15-30 mg in adults) or acetaminophen (15 mg/kg, or 1 g if patient >50 kg) may be administered intravenously.
In situations where moderate to severe postoperative pain is present, or oral analgesia is not possible, parenteral or intraspinal opioids, single-shot or continuous nerve blocks, and continuous epidural analgesia are used, often in combination techniques. Parenteral opioids are most safely administered by titration of small doses. Considerable variability in opioid requirements should be expected in surgical patients recovering in the PACU, and adequate analgesia must be balanced against the risk of excessive sedation and respiratory depression. Opioids of intermediate to long duration, such as hydromorphone 0.25-0.5 mg (0.015-0.02 mg/kg in children) or morphine 2-4 mg (0.025-0.05 mg/kg in children), are most commonly used. Meperidine is most often used in small doses to treat postoperative shivering. Opioid requirements are often markedly increased in patients with a history of chronic pain and chronic opioid therapy, because of opioid tolerance, and in patients with a history of opioid addiction, because of opioid tolerance and psychological dependence. Consultation with a pain specialist is often extremely helpful in these situations.
Analgesic effects of parenteral opioids usually peak within minutes of administration. Maximal respiratory depression, particularly with morphine and hydromorphone, may not occur until 20-30 min later. When the patient is fully awake, patient-controlled analgesia can be instituted for inpatients. Intramuscular administration of opioids is discouraged because delayed and variable onset (10-20 min or longer) and delayed respiratory depression (up to 1 h).
When an epidural catheter is used, epidural bolus administration of fentanyl (50-100 mcg) or sufentanil (20-30 mcg) with 5-10 mL of 0.1% bupivacaine can provide excellent pain relief in adults. Epidural morphine (3-5 mg) may also be used, but delayed respiratory depression with epidural administration of this opioid mandates close monitoring for 24 hr afterward (see Chapter 48).
Before the recovering patient is fully responsive, pain is often manifested as postoperative restlessness. Serious systemic disturbances (such as hypoxemia, respiratory or metabolic acidosis, or hypotension), bladder distention, or a surgical complication (such as occult intraabdominal hemorrhage) must also be considered in the differential diagnosis of postoperative agitation. Marked agitation may necessitate arm and leg restraints to avoid self-injury, particularly in children. When serious physiological disturbances have been excluded in children, cuddling and kind words from a sympathetic attendant or the parents often calms the pediatric patient. Other contributory factors include marked preoperative anxiety and fear, as well as adverse drug effects (large doses of central anticholinergic agents, phenothiazines, or ketamine). Physostigmine 1-2 mg intravenously (0.05 mg/kg in children) is most effective in treating delirium due to atropine and scopolamine. If serious systemic disturbances and pain are excluded, persistent agitation may require sedation with intermittent intravenous doses of midazolam 0.5-1 mg (0.05 mg/kg in children).
Postoperative nausea and vomiting (PONV) is common following general anesthesia, occurring in 30% to 40% of all patients. Moreover, PONV occurs at home within 24 hr of an uneventful discharge (postdischarge nausea and vomiting) in a significant number of ambulatory surgery patients. The etiology of PONV is usually multifactorial and associated with anesthetic and analgesic agents, the type of surgical procedure, and intrinsic patient factors, such as a history of motion sickness. It is also important to recognize that nausea is a common complaint reported at the onset of hypotension, particularly following spinal or epidural anesthesia.
Table 56-1 lists commonly recognized risk factors for PONV.
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