Airway, breathing, and circulatory responses (ABCs) are the first parameters to be assessed. Patients may be admitted to the PACU with an endotracheal tube in place to ensure airway patency. While the patient is transferred from the transport gurney to the PACU bed, this tube may become dislodged; tube patency and location should be checked immediately upon admission. Other patients will be admitted to the PACU without an airway device in place; these patients should be positioned to prevent aspiration, and airway patency should be assessed until the full return of protective reflexes.

Postoperative circulatory status should be identified upon admission. Volume depletion or volume overload should be treated early to prevent stressors upon the cardiovascular system. Volume replacement should be continued if ordered, and signs of volume status, including urine output measurements, should be performed. Peripheral tissue perfusion should be evaluated; signs of impending circulatory compromise should be identified and managed early to prevent tissue destruction. Cardiac monitoring should be performed to identify patients at risk for cardiac conduction disturbances, including dysrhythmia formation.

Core body temperature readings should be attained. Hypothermia is common in the postoperative phase and can complicate healing and return to a normal state. Obtaining core temperatures using infrared tympanic monitors and temporal thermometry has been recommended as the preferred noninvasive route of temperature measurement in this setting. However, obtaining core temperature measures via endotracheal, pulmonary artery, nasopharynx, or tympanic membrane (via a thermocouple) may be more accurate. The site chosen should be used consistently throughout the preoperative, perioperative, and postoperative phases [6,104]. It is important to recognize that accuracy will vary depending on the site, the device used, and the patient's condition. Patients should be assessed for chills and shivering as signs of hypothermia. Forced warm air devices may be used to assist in raising the core temperature of those patients who are hypothermic in the recovery area. If a temperature reading seems erratically low or high, a recheck is required.

Abdominal surgeries may be performed using a variety of approaches, including laparoscopy. Patients who undergo these procedures should be instructed to support their abdomen and surgical site when coughing or moving to reduce stress upon the incision site. The size and shape of the abdomen should be monitored at regular intervals, and any change should be immediately reported to the surgeon. Accurate intake and output measurements should be maintained, including the volume of fluid lost through drains. If possible, nausea and vomiting should be well controlled, as retching will put stress on the surgical site. Patients undergoing stoma formation should have the site regularly assessed for color and condition of the new stoma. These patients are at risk for fluid and electrolyte imbalances, especially hypovolemia, and assessment and replacement should be continued in the recovery period. Due to the length and extent of the procedures, abdominal surgery patients are commonly hypothermic upon return to the PACU. Patients undergoing abdominal procedures are at increased risk for DVT, paralytic ileus, infection, and wound dehiscence [7,8]. In addition, laparoscopic abdominal procedures may result in shoulder pain due to gas inflation of the abdomen.

Fracture repairs, total hip and/or knee replacements, and amputations are a few of the commonly performed orthopedic procedures. Slightly more women than men have these procedures; it is postulated that the bone loss that occurs in postmenopausal women puts them at increased risk of injury requiring surgical repair [9]. Patients who have orthopedic procedures require accurate assessment of their neurovascular status, including color, pulses, temperature, capillary refill, sensation, and movement of the affected area [10,11]. In the immediate postoperative period, these assessments should be completed at the same intervals as vital signs [95]. Body alignment should be maintained, as ordered. Supplemental traction devices, casts, or braces should be assessed for pressure areas. Edema is common, and elevation of the affected limb can reduce this risk. DVT risk is higher in this group of patients than any other patient population [10,11]. Therefore, recommendations for DVT prophylaxis should be closely adhered to. Compartment syndrome may develop. The patient may be at risk for osteomyelitis, and hypovolemia is common in the postoperative phase. Patients undergoing amputation require close monitoring of their distal perfusion.

Patients who have undergone an ophthalmologic procedure require special assistance in the recovery period. These patients may return to the PACU with eye patches over one or both eyes, which limits their ability to orient themselves to time or place. Ophthalmologic patients generally have a significant amount of pain that must be managed. Controlling rises in intraocular pressure (IOP) should be considered; vomiting, coughing, performance of the Valsalva maneuver, and pain lead to IOP rise and subsequent wound dehiscence. Signs of increasing IOP include pain around the orbit, blurry vision, changes in visual fields, and nausea. Osmotic diuretics are used to help manage rises in IOP.

PONV is a global problem affecting patients across the surgical span. This condition is generally characterized by nausea and vomiting that occurs within the first 24 hours after surgery[13]. Early PONV has an onset within the first two to six hours after surgery, commonly in phase I PACU. Late PONV occurs within 6 to 24 hours, often when the patient has been discharged or transferred from the recovery unit. Delayed PONV occurs more than 24 hours after surgery. The term post-discharge nausea and vomiting has been used to describe the onset of nausea and vomiting after discharge from the healthcare facility. No patient is immune to the development of PONV; it is reported that one-third of patients undergoing a surgical procedure will experience PONV. In high-risk patients, the risk is estimated to be as high as 70% to 80%[13,14]. It is critical for those managing postoperative patients to be aware of the triggers, methods for risk reduction, and management of this prevalent complication. PONV is the leading cause of unanticipated admission after planned ambulatory surgery[13]. The financial impact of prolonged care is estimated at millions of dollars per year.

Medications used for prophylaxis of PONV include the serotonin receptor antagonists. Serotonin is a neurotransmitter that stimulates the vomiting cascade in the brain; blocking its uptake limits the incidence of PONV. Ondansetron is often considered the first-line drug, although its relative costs and incidence of headache after use have made other serotonin receptor antagonists increasingly popular. Ondansetron has greater antiemetic than antinausea effects [14,15,109]. Dolasetron may be considered, although its use is limited in patients with prolonged conduction defects, and the drug is no longer marketed in the United States [14,16]. Granisetron has been shown to have some efficacy for PONV prophylaxis [14,109]. Palonosetron is a second-generation receptor antagonist and has been found to be more effective at lower doses than granisetron and ondansetron in preventing PONV [14,109]. Ondansetron and granisetron are most effective in the prophylaxis of PONV when given at the end of surgery [14,109]. The administration of dexamethasone has been found to improve the efficacy of the serotonin receptor antagonists, especially when administered prior to initiation of surgery [14,17,109].

Complementary therapies can also be considered and used as appropriate. The most common therapy discussed in the literature is the use of the P6 acupoint stimulation [15,18,19]. This point, located on the inside of the wrist, is frequently used in acupressure and acupuncture regimens when stomach distress is noted by the patient. Other interventions that may be considered include relaxation therapies, music therapy, aromatherapy (e.g., lavender), and herbal therapy, including ginger root [20,21,22,23].

Malignant hyperthermia is a complication that normally begins in the operating room but requires continued care and vigilance for recurrence in the postoperative phase of care. Malignant hyperthermia is a disease of skeletal muscle and has genetic origins. The onset of complications begins when a triggering agent is administered to a susceptible patient. The skeletal muscles begin to contract in response to the trigger, and this hypermetabolic state leads to the marked temperature rise, which gives the disorder its name. If left untreated, the mortality rate is high. In cases that receive treatment, the risk of permanent disability exists [24,25].

Malignant hyperthermia is most common in children and male patients. Many first cases are seen in children undergoing surgical corrective procedures. The most widely recognized triggers include the volatile gases (e.g., halothane, isoflurane, enflurane, desflurane) and succinylcholine [24]. After exposure, the patient may experience muscle rigidity, beginning with the masseter muscle and followed by global muscle rigidity, a significant rise in body temperature, and the development of systemic metabolic acidosis. Although these signs are identified as the "classic" signs of developing malignant hyperthermia, it is possible for the patient to have minimal muscle contraction and a delayed onset of elevated fever. However, all patients experience a rapid rise in exhaled carbon dioxide, which can be identified on end-tidal carbon dioxide monitors used in the operating suite. This is often the first sign of the condition. Upon recognition of the developing syndrome, the triggers are removed from the patient and immediate life-saving treatment is initiated.

Although a rise in body temperature is common with this complication, it can be controlled and limited. The other conditions that arise carry a much higher risk of morbidity and mortality. Early signs include elevated expired carbon dioxide and developing cardiac dysrhythmias, such as tachycardia and ventricular dysrhythmias, as a result of elevated potassium levels. The skin feels warm to the touch, yet the core temperature remains normal. As the disorder progresses, late signs include the development of a high core temperature, which can increase as rapidly as 1°C every five minutes. Temperatures have been reported as high as 46°C (114.8°F). The continuous muscle contraction causes a rise in the serum level of ionized calcium and a subsequent rise in the serum potassium level. Coagulopathy develops as fibrinogen levels fall. Respiratory acidosis develops in response to rising carbon dioxide levels, with the pH falling below 7. Muscle contraction causes a release of myoglobin, leading to rhabdomyolysis. If left untreated, the patient can progress to multiorgan dysfunction syndrome (MODS), which includes renal failure, cardiac failure, and death if not treated in an immediate fashion [100].

The development of dantrolene, a skeletal muscle relaxant, changed the treatment of malignant hyperthermia. Prior to its development, the mortality rate for malignant hyperthermia was as high as 70% to 80%; with immediate dantrolene use, the mortality rate for malignant hyperthermia can be as low as 2% [25,26]. Dantrolene contains 3 g of mannitol per vial, which helps prevent the renal failure commonly seen with developing rhabdomyolysis. Dosing of dantrolene varies from 2.5 mg/kg (the common starting dose) up to 10 mg/kg, depending upon the severity of symptoms [16,111]. Administration is time-consuming; the drug comes as a powder in the vial and must be reconstituted with sterile water without a bacteriostatic agent. Shaking and warming the vial helps to dissolve the powder. It is recommended that 36 vials of dantrolene be available at all times to treat a single case of malignant hyperthermia. Once reconstituted, the drug is orange-yellow in appearance and is rapidly infused. The effects occur within minutes and include relaxation of the muscle contractions and a fall in core temperature. If no response is seen, the drug is repeated at a higher dose.

While dantrolene may be a life-saving drug, it is only one of the many measures that should be instituted to prevent the lifelong sequelae that can develop secondary to malignant hyperthermia. As the core temperature begins to rise, neurologic effects may become apparent. The rising body temperature should be controlled with cooling measures. Iced normal saline solution is infused at a rate of 15 mL/kg [24,111]. Internal cooling can be instituted using cold nasogastric, bladder, rectal, and/or peritoneal lavage. Cooling blankets can be applied to initiate surface cooling; this measure is much more beneficial in pediatric patients due to their high body surface area to body mass ratio.

Despite the best efforts to maintain normothermia in surgical patients, a large percentage of patients experience postoperative hypothermia [28]. Postoperative hypothermia is defined as a core body temperature of less than 36°C (96.8°F) [29]. Regardless of the core temperature, any time a patient exhibits signs of hypothermia (e.g., shivering, peripheral vasoconstriction, piloerection) measures to warm the patient should be instituted.

One of the consequences of hypothermia is the development of muscle contractions to maintain body temperature, also known as shivering. Postoperative shivering not only increases the patient's discomfort, it can significantly increase the body's oxygen and metabolic demands. Meperidine is recommended (off-label) to manage postoperative shivering and is administered once at 12.5–50 mg IV [16,30,112]. The antiemetic ondansetron also has been evaluated for use in the management of postoperative shivering. A meta-analysis to evaluate the agent found no difference in the incidence of postoperative shivering when compared with meperidine; compared with placebo, ondansetron significantly reduced postoperative shivering [31]. Supplemental oxygen should be administered to thwart the onset of hypoxemia. In addition to preventing other complications, achieving and maintaining normothermia can greatly enhance the patient experience.

Reassessment of pain should be performed whenever intervention is undertaken. Within 30 minutes of intravenous administration, the patient should be re-evaluated. Oral medications with a slower onset of action require reassessment at 45 to 60 minutes after administration. The time of onset for oral medication can vary with an individual's medical history and ability to metabolize the drug administered [101]. Each time the patient reports a new or changed pain, an assessment should be performed.

Systemic narcotics are the cornerstone of the management of moderate-to-severe postoperative pain. This drug class has the advantages of rapid onset, ability to be given by a number of routes, and general reversibility with naloxone. Tolerance may develop more quickly with these medications, so close monitoring is critical to success. Side effects include sedation, confusion, respiratory depression, nausea and vomiting, pruritus, constipation, and urinary retention. Histamine release can occur with various narcotics and should be considered when administering these drugs to asthmatics. Morphine is the gold standard to which all other system narcotics are held. It is inexpensive and provides adequate pain relief for a vast array of patients. Other narcotics to consider include hydromorphone, oxycodone, nalbuphine HCl, hydrocodone, and codeine. Meperidine is still widely used for postoperative pain management, although its use is dwindling due to associated side effects and the fact that newer, better drugs are available.

The majority of surgical patients are placed in the dorsal recumbent position, including patients undergoing abdominal, mediastinal, and cardiac surgeries. While this position may seem to be harmless, it is not without risks. Intraoperatively, there may be pressure on the diaphragm, leading to respiratory difficulties, and abdominal organs can put pressure on the inferior vena cava. The risks increase in obese and pregnant patients, and these patients should be placed in the left lateral decubitus position to the extent possible during the procedure. Venous pooling occurs, leading to a postural hypotension that becomes evident in the postoperative phase when the patient tries to sit or stand. Pressure point compression, leading to ischemic tissue, occurs at the elbows, sacrum, shoulder, heels, and occiput at the back of the head. The hard, flat surface and alteration of the normal curvature of the lower spine may lead to complaints of backache. Improper positioning of the extremities can lead to compression of nerves and vessels, leading to a lack of muscle control in the PACU. Patients should be evaluated before, during, and after surgery to ensure that measures are undertaken to prevent these complications. One study noted a reduction in sacral wounds when sacral foam dressing was applied preoperatively [102].

Placing patients in the prone position is used in back, rectal, and spinal surgeries. During surgery, the patient experiences both chest and abdominal compression, which can lead to respiratory and circulatory problems. Positioning of the extremities is critical; overextension or flexion can lead to nerve and joint injuries. Protection of the head and face is critical, as eye abrasions and ear compression can occur. Positioning appliances, such as the Wilson frame, or rolled blankets placed under the chest are used to alleviate chest restriction. Finally, because the patient's head was rotated to allow the anesthesia provider maximum access to the patient's head and airway, the patient may awaken with significant neck pain.

Recognizing the early signs of respiratory complications by assessing vital sign trends and oxygen saturations can reduce the risk of further compromise. Stimulating patients when they begin to arouse postoperatively by encouraging deep breathing and respiratory exercises will ensure that full lung expansion is achieved early. Supplemental oxygen may be of benefit; however, practitioners should be aware that this may mask the signs of falling oxygen saturations. Therefore, when oxygen is utilized, other assessment parameters should be performed. The cautious use of postoperative analgesics is recommended, but finding a balance between pain control and limiting respiratory side effects can be challenging. When respiratory insufficiency becomes a true complication, reversal of narcotics and/or benzodiazepines may be necessary. If reversal agents are utilized, alternatives to narcotics should be considered to ensure adequate pain management.

Risk factors for NCPE include obesity, a short neck, and a history of sleep apnea. It is more commonly seen in ENT patients and patients with a history of a difficult intubation [42]. In the postoperative period, early extubation can lead to the development of NCPE as the patient is unable to manage the secretions, leading to airway blockage. Suctioning the patient prior to extubation can reduce the risk of this complication. All patients with a risk factor for NCPE should be monitored for at least 60 minutes postextubation.

Postoperative hypertension is of significant concern due to the associated consequences of the complication, including the risk of stroke. Approximately one in three Americans is hypertensive; therefore, it is expected that many patients undergoing surgery will be hypertensive during the baseline measurement of their vital signs [46]. If hypertensive medications are held during the preoperative phase of care, it is expected that the patient will be slightly hypertensive in the recovery phase. The biggest concern is if the patient's diastolic pressure exceeds 120 mm Hg. If this is accompanied by headache, blurred vision, or changes in level of conscious, immediate intervention should be undertaken.

Signs of developing DVT include swelling, redness, tenderness, and a feeling of warmth over the developing clot. Homans' sign, pain upon dorsiflexion of the foot, is present. The extremity may become swollen; however, this is a late sign [116]. When signs appear, the clot has already formed and the risk is high for pulmonary emboli formation.

Regaining consciousness and awareness following anesthesia is impacted by many factors. When a patient does not awaken within 60 to 90 minutes following anesthesia, this is referred to as delayed awakening. The medications administered to achieve anesthesia are common culprits of delayed awakening. When a patient has received inhaled gases, awakening is directly related to alveolar ventilation. With poor ventilation, the gases remain in the pulmonary tree, prolonging arousal. Premedications that have a longer length of action than the procedure can cause the patient to remain somnolent during this period. Midazolam, with its short length of action, is commonly used as a premedicant to prevent this occurrence.

While many patients awaken as expected, some patients' arousals are neither smooth nor uneventful. Emergence excitement or delirium has been noted in 10% of the general surgical population [53,117]. Emergence excitement is defined as a state of restlessness and disorientation during arousal. Patients may be confused and unable to process their thoughts in a normal pattern. Emergence delirium is an extreme form of excitement in which the patient is shouting, agitated, and thrashing about and may be at risk for harming himself/herself or others. Patients also generally do not respond appropriately to commands [53,117].

The priority of those caring for a patient exhibiting signs of emergence excitement or delirium is to ensure that the patient and other staff members are safe from harm. Violent movements may cause the patient to hit his or her arms, legs, or head against the side rails, so pillows should be placed to pad these areas. While restraints may be considered, their use may only increase the agitation.

Recovery can be tested by evaluating the following parameters: ability to open eyes wide, sustained protrusion of the tongue, sustained hand grip for at least five seconds, sustained head lift for at least five seconds, and the ability to cough effectively [59]. Achievement of certain respiratory parameters, including a tidal volume of at least 5 mL/kg, a vital capacity of at least 15–20 mL/kg, and/or an inspiratory force of 20–25 cm, may also indicate recovery. However, in many settings, evaluation using these parameters has had limited success in preventing the occurrence of residual paralysis [57].

There are a large number of factors that potentiate the development of neuromuscular blockade. It is important to assess for these factors and develop a plan of care based on these interactions. Medications and conditions potentiating the development of neuromuscular blockade include:

Antibiotics

Sedatives

Inhalation gases

Hypothermia

Many commonly prescribed cardiovascular medications

Another cause of volume overhydration is the absorption of irrigating fluid. This can occur whenever irrigating fluid is used, and patients can develop signs of hypertension and edema formation. It is not uncommon for patients undergoing TURP to absorb 1–1.5 liters during the procedure, also known as TURP syndrome [66]. Patients can develop life-threatening complications secondary to this volume overload. TURP syndrome occurs in only 2% of patients undergoing a TURP procedure. Caregivers may therefore be unfamiliar with the syndrome and may not recognize the signs and symptoms, which include [67]:

Excessive urine output

Signs of pulmonary congestion (e.g., a wet cough, rales, rhonchi)

Headache

Signs of congestive heart failure

Hyponatremia

Edema formation

The absence of bowel motility after surgery is known as a postoperative ileus. There is no bowel obstruction causing this hypomotility; it is a physiologic response to surgical intervention on the abdominal tract. Postoperative ileus occurs most commonly following intraperitoneal surgery, but it may also be identified after retroperitoneal and extra-abdominal surgeries. The lack of motility leads to the accumulation of fluid and gas in the GI tract, causing bloating, pain, discomfort, and nausea with or without vomiting, and can extend the hospital stay of postoperative patients [68].

The most common symptoms of postoperative ileus are lack of bowel movement and absence of bowel sounds. Unlike an obstruction, in which bowel tones are present, this is an adynamic state in which there is no bowel motility and no movement of gastric contents. After surgery, the bowel regains function; the small bowel will regain function within hours. The stomach will resume function at one to two days postoperatively, and the colon will eventually regain motility at three to five days after surgery. This pattern of recovery is typically seen in patients without comorbid conditions. Complications such as sepsis, metabolic disorders, pneumonia, and trauma can significantly delay recovery times. In addition, medications commonly used in the recovery phase of care, including narcotics, anticoagulants, and antacids, can alter recovery.

Although the occurrence is rare (i.e., risk of 0.8%), several factors accurately predict the development of postoperative acute renal failure [68,71,72]:

Advanced age

Emergent surgery

Liver disease

High body mass index (BMI)

High-risk surgery

Peripheral vascular occlusive disease

Chronic obstructive pulmonary disease requiring bronchodilator therapy

Managing the airway of a child is critical to success. It is imperative to remember that the larynx is more cephalad and anterior than in the adult patient. This anatomic difference requires proper head positioning at all times. The child should be placed in the sniffing position, maintaining a jaw thrust position. Additionally, the airway diameter is narrow, and airway swelling can lead to rapid onset of airway obstruction. Ensuring good air movement through the trachea is an important assessment intervention.

As previously noted, common postoperative complications in children include hypothermia, nausea and vomiting, malignant hyperthermia, and emergence delirium. The interventions for these complications have been discussed in this course. Unique to children is the development of postextubation croup. Subglottic edema develops secondary to prolonged intubation, trauma during intubation, or as a result of coughing against the endotracheal tube. This type of croup is more common in young children between 1 and 3 years of age [77]. The symptoms usually occur within 30 minutes of extubation and peak at six to eight hours post-extubation. The child exhibits the signs of croup, including the barking cough, stridor, and chest retractions. With treatment, these signs will subside within 24 hours. Management includes administration of cool, humidified oxygen and nebulized epinephrine. The role of corticosteroids remains controversial [78,121].

As humans age, the cardiovascular system deteriorates. The myocardium is less sensitive to catecholamine release, and cardiac output drops by half [80]. The vascular system stiffens, and responses to blood pressure changes are not as beneficial, causing compensatory responses to be blunted. This weakening of the cardiovascular system impacts elderly patients' responses to medications; the lower cardiac output leads to a slower onset of drug action and a longer length of drug action secondary to slower metabolism.

As morbid obesity (also referred to as severe obesity or class 3 obesity) becomes an increasingly common condition in our society, the need and desire for bariatric surgery has exploded [85,93]. Morbidly obese patients (defined as persons with a BMI of 40 or greater) are requesting surgical intervention to put an end to the risk they are exposed to when overweight [86]. Morbid obesity increases the risk of hypertension, diabetes, hyperlipidemia, coronary heart disease, and stroke [87,125]. These conditions increase the risk of complication development when undergoing surgery, including bariatric surgery.

There are two major types of bariatric surgery: those that restrict the limit of intake and those that restrict absorption. Restrictive procedures, including gastric banding and sleeve gastrectomy, reduces the amount of food the stomach can hold. Malabsorptive procedures, including biliopancreatic diversion with duodenal switch (BPD/DS), divert the gastric contents so the food bypasses the small intestine where food and nutrient absorption occur, preventing absorption. The criterion standard of bariatric surgery, Roux-en-Y gastric bypass, combines both malabsorption and restrictive techniques [94]. These types of procedures are associated with a weight loss of 40% to 80% of excess weight in patients, with maintenance of approximately 50% or greater at five-year follow-up [87,94]. The other advantage of bariatric surgery is reduction or removal of life-threatening complications of obesity. In one study, 77% of bariatric surgery patients with preoperative diabetes no longer required medication after weight loss [87]. The most effective surgery for patients with diabetes is BPD/DS [94]. Ten of 11 randomized controlled trials from around the world that compared surgery with medical treatment of type 2 diabetes found surgery to be superior at achieving remission of diabetes or glycemic improvement. Surgery was also superior at improving weight loss and reducing medication burden [88].