The postanesthetic observation phase of management is the few hours immediately after operation during which the acute reaction to operation and the residual effects of anesthesia subside. This carried in the The postanesthesia care unit (PACU). All patients should be monitored in this specialized unit initially following major procedures unless they are transported directly to an intensive care unit.

While en route from the operating room to the PACU, the patient should be accompanied by a physician and other qualified attendants.

In the PACU, the anesthesiology service generally exercises primary responsibility for cardiopulmonary function.

The surgeon is responsible for the operative site and all other aspects of the care not directly related to the effects of anesthesia.

Care is principally directed at maintenance of homeostasis, treatment of pain, and prevention and early detection of complications.

The primary causes of early complications and death following major surgery are acute pulmonary, cardiovascular, and fluid derangements.

The patient can be discharged from the recovery room when cardiovascular, pulmonary, and neurologic functions have returned to baseline, which usually occurs 1-3 hours following operation. Patients who require continuing ventilatory or circulatory support or who have other conditions that require frequent monitoring are transferred to an intensive care unit.



Postoperative Complications

Nausea and Vomiting

The etiology of postoperative nausea and vomiting is multifactorial.

The vomiting centre is located in the area postrema of the brainstem and receives vagal afferents from the gastrointestinal tract. Selective serotonin receptor antagonists like ondansetron, dolasetron, and granisetron have proven to be effective in alleviating postoperative nausea and vomiting with minimal side effects when administered just prior to the end of a case. Other classes of drugs including anticholinergics, dopamine antagonists and antihistamines may also be utilized, but have significant side effects. Clonidine, dexamethasone, and acupuncture have also been found to be effective. Combination of therapies for the prevention of postoperative nausea and vomiting provides maximal benefit.

Nausea and vomiting are troublesome complications of anesthesia, especially in young women.

Postoperative Pain

The management of postoperative pain should begin in the operating room.

The goal is to minimize any potential sensitization of the spinal cord and brain propagated by tissue injury and pain stimuli. One method of the preemptive analgesia involves central neuraxial blockade.

However, if a general anesthetic is used, local field block in the area of the incision is effective as well. Opioids are most widely used to control postoperative pain but have significant side effects like ileus, respiratory depression, nausea, and vomiting.

Nonsteroidal anti-inflammatory drugs (NSAIDs) may also be used for postoperative pain control in these patients. (When?)

Resapiratory Complications

A 73-year-old man with a history of COPD and an forced expiratory volume in 1 second (FEV1) of 1.3 L (40% predicted) is undergoing an elective cholecystectomy. In the postoperative period, which of the following interventions has been shown to decrease the likelihood of pulmonary complications?

The correct answer is B.

 Perioperative pulmonary complications are common, particularly after upper abdominal surgery; emergency or prolonged (3- to 4-hour) surgery; aortic aneurysm repair; vascular surgery; or major abdominal, thoracic, neurologic, head, or neck surgery; and with general anesthesia. Patients at higher risk of pulmonary complications should undergo incentive spirometry, deep-breathing exercises, cough encouragement, postural drainage, percussion and vibration, suctioning and ambulation, intermittent positive-pressure breathing, continuous positive airway pressure, and selective use of a nasogastric tube for postoperative nausea, vomiting, or symptomatic abdominal distention to reduce postoperative risk. Pain control is also important for promoting respiratory clearance, and narcotics may be used appropriately. Pulmonary artery catheterization, total parenteral nutrition, and total enteral nutrition have not been shown to reduce perioperative respiratory complications.


Patients who need continued cardiopulmonary support or continued invasive monitoring to avoid major morbidity and death are transferred to an intensive care unit.





Postoperative Fever

The most common cause of postoperative fever in the first 24 hours is atelectasis (usually low-grade fever). [What is te mechanism?]. Prevent or treat with early ambulation, chest physiotherapy/percussion, incentive spirometry, and proper pain control. Both too much pain and too many narcotics increase the risk of atelectasis.

The mnemonic “water, wind, walk, wound, and wonder drugs” will help you recall the causes of postoperative fever: water, urinary tract infection; wind, atelectasis/pneumonia; walk, deep venous thrombosis; wound, surgical wound infection; wonder drugs, drug fever. If daily fever spikes occur, think about an intraabdominal abscess; consider a CT scan to locate the abscess. Abscesses often need surgical or CT-guided catheter drainage.

Fascial/wound dehiscence typically occurs 5–10 days postoperatively. Look for leakage of serosanguineous fluid from the wound (often after the patient coughs or strains), which is especially associated with wound infection. Treat with antibiotics (if secondary to infection) and reclosure of the incision.

Fluid management(See: Fluid and Electrolyte Management)

Age of Patient





Content 2

Content 3

Daily parenteral maintenance fluids and electrolytes for an average adult includes 2500–3000 mL of 5% dextrose in 0.2% saline solution (34 mEq Na+ plus 34 mEq Cl/L) with 30 mEq/L of KCl. (What is the rationale?)


Weight loss or gain is the best indication of water balance. Insensible water loss should be considered in febrile patients. Water loss increases by 100–150 mL/d for each degree of body temperature over 37 °C.

In patients requiring maintenance and possibly replacement of fluid and electrolytes by parenteral infusion, the total daily ration should be administered continuously over 24 hours to ensure optimal utilization.


If intravenous fluids are the only source of water, electrolytes, and calories for longer than a week, parenteral nutrition containing amino acids, lipids, trace metals, and vitamins may be indicated. (See Chapter 29.)


For parenteral alimentation, 620 mg (20 mmol) of phosphorus is required for every 1000 nonprotein kcal to maintain phosphate balance and to ensure anabolic function. For prolonged parenteral fluid maintenance, a daily ration is 620–1240 mg (20–40 mmol) of phosphorus.



The aim of maintenance therapy is to replace water and electrolytes lost under ordinary conditions. In the perioperative period, maintenance fluid administration often does not sufficiently account for the increased fluid requirements caused by third-space losses into the interstitium and gut. Table 1 outlines a plan for perioperative maintenance fluid therapy.

Table 1. Guide for Early Postoperative and Maintenance Therapy

Age (mo) < 12 h After Surgery Maintenance Fluids
< 6 10% dextrose in water (D10W) with 0.45% NaCl at 1.5 times the maintenance rate D10W with 0.2% NaCl plus KCl 10-20 mEq/L at maintenance rate
>6 5% dextrose in water (D5W) with RL solution at 1.5 times the maintenance rate D10W with 0.45% NaCl plus KCl 10-20 mEq/L at maintenance rate

The fluid for maintenance therapy replaces losses from 2 processes: evaporative (ie, insensible) losses and urinary and GI losses. Evaporative losses consist of solute-free water losses through the skin and respiratory tract. Insensible water loss tends to be higher in preterm infants. Evaporative loss through the skin makes up about 70% of insensible water loss whereas the remainder is lost from the respiratory tract. Ambient humidity and temperature affect insensible losses. Patients receiving humidified air have less insensible loss than those not receiving humidified air. Patients with hyperthermia or tachypnea similarly have exaggerated insensible losses. Although replacement of increased insensible water loss is important, the emphasis on therapy focus on prevention of excessive insensible water loss rather than on replacement alone.

In a euvolemic state, urinary losses are 280-300 mOsm/kg of water, with a specific gravity of 1.008-1.015. In some circumstances (eg, diabetes insipidus, prematurity), the production of dilute urine is obligatory, and the volume of maintenance fluids must be appropriately increased. In other circumstances (eg, excessive ADH secretion, physiologic stress), a patient may be unable to decrease urine osmolality to 300 mOsm/kg of water, and the volume of maintenance fluids must be decreased. Under euvolemic conditions, urinary losses account for two thirds of total maintenance fluids.

Total requirements for maintenance fluid can be estimated from common formulas, such as those listed below. Frequently assess the patient's condition during maintenance therapy. If the estimate is correct, the patient's electrolyte levels should remain stable, and the patient should remain clinically euvolemic. Abnormal electrolyte levels or clinical signs of hypervolemia or hypovolemia indicate a need to reassess each component of the patient's maintenance therapy.

Table 2. Daily Fluid Requirements During First Week of Life (mL/kg/d)[1] (Open Table in a new window)

Birth Weight Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7
< 1000 g 80 100 120 130 140 150 160
1000-1500 g 80 95 110 120 130 140 150
>1500 g 60 75 90 105 120 135 150

A guide for maintenance fluid therapy for children is as follows:

  • 0-10 kg - 100 mL/kg/d (4 mL/kg/h)
  • 10-20 kg - 1000 mL/d + 50 mL/kg/d (40 mL/h + 2 mL/kg/h)
  • Greater than 20 kg - 1500 mL/d + 25 mL/kg/d (60 mL/h + 1 mL/kg/h)

Replacement therapy

Replacement fluid therapy is designed to replace ongoing abnormal fluid and electrolyte losses. Because the constituents of these losses often substantially differ from the composition of maintenance fluids, simply increasing the volume of maintenance fluids to compensate for these losses may be hazardous. The authors generally replace large-volume stoma or other fluid losses with a physiologic equivalent fluid, as shown in Table 2.

As an alternative, measuring the electrolyte content of these losses and replacing them milliequivalent for milliequivalent or milliliter for milliliter may be preferred in select circumstances. For the patient under severe physiologic stress or for those undergoing extensive surgery, calculate third-space losses into the interstitium, and adjust replacement therapy accordingly.

Table 3. Typical Electrolyte Composition of Body Fluids for a Child with Abnormal Fluid and Electrolyte Losses and of Common IV Fluids (Open Table in a new window)

Body or IV Fluid Electrolytes (mEq/L)
Na+ K+ Cl- HCO3 -
Gastric 70 5-15 120 0
Pancreas 140 5 50-100 100
Bile 130 5 100 40
Ileostomy 130 15-20 120 25-30
Diarrhea 50 35 40 50
RL solution 130 4 109 28
0.9% NaCl 154 0 154 0
0.45% NaCl 77 0 77 0



Although there is an early phase of negative nitrogen balance following surgical stress, it may be shortened or even aborted by appropriate nutritional support before and immediately after surgery.17 Early institution of enteric feeding has been shown to be of benefit, including a reduction in septic sequelae, in surgical patients undergoing intra-abdominal procedures.18 If daily caloric intake goal could not be achieved with enteral feeding alone before day 8 of ICU admission, institution of parenteral nutritional support should be considered to prevent further loss of muscle mass.19 Earlier initiation of parenteral nutrition appears to be associated with more infectious complications, delayed recovery, and higher health care costs.19 Adequate nutrition affects not only the maintenance of muscle mass, but also the maintenance of respiratory function, and thus both dependence on ventilatory support and weaning from mechanical ventilatory assistance.




Intermediate care is usually provided on an inpatient nursing unit until the patient’s recovery can continue at home during the convalescent phase.

Content 4

Which of the following are routine components of the first 24-hour postoperative check in patients who have undergone colon resection?

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The correct answer is E. You answered E.