32: Postanesthetic Care

Published on 06/02/2015 by admin

Filed under Anesthesiology

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1277 times

CHAPTER 32 Postanesthetic Care

Michael M. Sawyer, MD

1 Which patients should be cared for in the postanesthetic care unit?

Postanesthetic care unit (PACU) care is traditionally divided into phase 1, during which monitoring and staffing ratios are equivalent to an intensive care unit, and phase 2, wherein transition is made from intensive observation to preparation for care on a surgical ward or at home.

Fast-track recovery is emerging because of fast-offset anesthetic agents and adjunctive drugs. Most patients who have had monitoring plus sedation or extremity regional anesthesia should be appropriate for fast track recovery, bypassing phase 1. Typically, however, after inhalation general anesthesia or neuraxis regional anesthesia, a period of phase 1 care is required. Coexisting disease, the surgical procedure, and pharmacologic implications of the anesthetic agents used ultimately determine the most appropriate sequence of postoperative care for each patient.

2 Review important considerations as the patient is about to be moved from the operating room to the postanesthetic care unit

Transport from the operating room (OR) to the PACU can be a dangerous time for patients. Recent PACU designs have been developed to make this trip as short as possible. However, many institutions still are burdened with PACUs remote from the ORs. This has also become an issue with the development of many newer satellite locations where anesthetics are performed (e.g., magnetic resonance imaging). Before transport a patient should be able to maintain a patent airway with spontaneous respirations. The use of supplemental oxygen for transport is recommended. More complicated patients require the use of a transport monitor to facilitate close assessment.

3 Describe the process for postanesthetic care unit admission

A report is given by the anesthesia caregiver to the PACU nurse, reviewing the patient’s prior health status, surgical procedure, intraoperative events, agents used, and anesthetic course. The use of muscle relaxants and reversal of neuromuscular blockade, the intraoperative interventions for analgesia, and the intraoperative fluids and blood products received guide in planning PACU care. Initial assessment of the patient by the PACU nurse includes vital signs, baseline responsiveness, adequacy of ventilation, and adequacy of analgesia. Various scoring systems have been used to allow numeric scoring of subjective observations as an indicator of progress toward discharge. The Aldrete scoring system (Table 32-1) tracks five observations: activity, respiratory effort, circulation, consciousness, and oxygenation. Scales for each are 0 to 2, and a total score of 8 to 10 indicates readiness to move to the next phase of care. Regression of motor block in the case of regional anesthesia is also an important determinant of readiness for discharge.

TABLE 32-1 The Aldrete Score

Activity
Able to move four extremities
Able to move two extremities
Not able to move extremities voluntarily or on command

2
1
0

Respiration
Able to breathe and cough
Dyspnea or limited breathing
Apneic
2
1
0
Circulation
BP ± 20% of preanesthetic level
BP ± 21%-49% of preanesthetic level
BP ± 50% of preanesthetic level
2
1
0
Consciousness
Fully awake
Arousable on calling
Not responding
2
1
0
O2 saturation
Maintain O2 saturation >92% in room air
Needs O2 to maintain O2 saturation >90%
O2 saturation <90% with O2 supplement
2
1
0

BP, Blood pressure.

Adapted from Aldrete AJ, Krovlik D: The postanesthetic recovery score, Anesth Analg 49:924–933, 1970.

4 What monitors should be used routinely in the postanesthetic care unit?

The level of care will depend on the clinical status of the patient. Pulse oximetry and periodic blood pressure monitoring should be used routinely on all patients. Interestingly, routine electrocardiogram (ECG) monitoring has not been found to be of value in patients without risk factors of coronary disease. Finally temperature, urine output, and surgical drainage require monitoring as appropriate.

5 What problems should be resolved during postanesthetic care?

image Hypoventilation: The patient should be breathing easily and able to cough on command and oxygenate to near preanesthetic levels.
image Hemodynamic stability: Blood pressure should be within 20% of preanesthetic measurements with stable heart rate and rhythm.
image Attenuated sensorium: The patient should be fully awake and voluntarily move all extremities.
image Postoperative pain: Pain management should no longer require continuous nursing intervention.
image Postoperative nausea and vomiting (PONV): PONV should be treated aggressively since it is associated with prolonged length of stay in the PACU and decreased patient satisfaction with the perioperative experience.

6 How is ventilation adversely affected by anesthesia?

Residual neuromuscular blockade, opioid effects, and lingering effects of inhalational anesthesia can result in postoperative hypoventilation (Table 32-2).

TABLE 32-2 Ventilation Problems in the Postanesthetic Care Unit

Problem Symptoms Treatment
Residual neuromuscular blockade Uncoordinated, ineffectual respiratory effort Neostigmine, 0.05 mg/kg IV
Opioid narcosis Slow ventilation, sedated and difficult to arouse Respiratory support, naloxone 0.04–0.4 mg IV
Residual inhalation anesthesia Sleepy, shallow breathing Encourage deep breathing

7 Describe the appearance of residual neuromuscular blockade

The patient appears floppy, with poorly coordinated and ineffective respiratory muscle activity. The patient may complain that breathing is restricted and efforts to deliver supplemental oxygen are suffocating. The patient is unable to sustain a head lift or hand grasp. In the worst case weakness of the pharyngeal muscles results in upper airway collapse and postextubation airway obstruction. Neither a good response to train-of-four testing in the operating room nor spontaneous rhythmic ventilation before extubation rules out residual neuromuscular blockade.

8 How do opioids and residual volatile anesthetics affect breathing?

Slow rhythmic breathing or apneic pauses in a patient who is hard to arouse suggest residual narcosis. In contrast to the patient with residual muscle relaxation, the narcotized patient is often unconcerned about ventilation despite obvious hypoxia. Hypoventilation also slows elimination of volatile anesthetics, potentiating hypoventilation. Surprising degrees of hypercapnia may be found, even with relatively normal pulse oximetry values when supplemental oxygen is delivered.

9 How should these causes of hypoventilation be treated?

Hypoventilation resulting from residual neuromuscular blockade should be treated urgently and aggressively. Additional reversal agents may be given in divided doses up to the usual dose limitations. Treatment decisions for residual narcosis may prove to be more problematic. Opioid antagonism for the sake of ventilatory support reverses adequate analgesia. The agonist/antagonist class of analgesic drugs seldom yields a net improvement in ventilation when used for reversal of opioid-induced hypoventilation. Usually the best alternatives are airway support with nasal or oral airways and continuous stimulation until the clinical effects of the opioid on ventilation and responsiveness have resolved. Other supportive measures include increasing inspired oxygen concentrations (FiO2) by switching from nasal cannula to mask (Table 32-3). However, an important caveat—increasing FiO2 does not reverse hypoventilation, only masks it.

TABLE 32-3 Predicted FiO2 with Supplemental Oxygen Delivery

System Delivery Flow (L/min) FiO2 Predicted
Nasal cannula 2 0.28
Nasal cannula 4 0.36
Face mask 6 0.50
Partial rebreathing mask 6 0.6
Total rebreathing mask 8 0.8

FiO2, Fractional inspired oxygen concentration.

10 The patient has been delivered to the postanesthetic care unit. Oxygen saturations are noted to be in the upper 80s, and chest wall movement is inadequate. How should the patient be managed?

Establish a patent airway (chin lift, jaw thrust) and administer oxygen. Suction the patient’s airway if needed. Is the trachea in midline? Once the airway is patent, observe and auscultate the chest. Is the patient hypoventilating? Perhaps reversal of opioid effect is necessary. Does the abdomen distend and the chest retract with inspiration (paradoxical respirations), suggesting airway obstruction or inadequate reversal of neuromuscular blockade?

Assess the patient’s strength by hand grip and sustained head lift. Are there wheezes or rales, requiring inhaled β-agonists or diuresis? Palpate pulses and listen to the heart because circulatory depression causes oxygen desaturation. The patient may require assisted ventilation or reintubation.

Most hypoxia in the PACU is caused by atelectasis, which is treated by sitting the patient upright, asking him or her to breathe deeply and cough, incentive spirometry, and nasal BiPap.

11 The patient develops stridorous breath sounds. Describe the likely cause and the appropriate management

A likely cause of stridorous breath sounds in the early postextubation period is laryngospasm, although other causes of upper airway obstruction (e.g., postextubation croup, expanding hematomas, soft-tissue swelling) should be excluded. Laryngospasm may be precipitated by extubation during light planes of anesthesia or secretions falling on the vocal cords. If laryngospasm is incomplete, the patient will have stridorous breath sounds. If laryngospasm is complete, little air movement is possible, and breath sounds will be absent.

An assessment of airway obstruction is facilitated by observing the chest and abdominal wall. Paradoxical motion, in which the chest contracts as the abdomen expands, suggests that inspiration is being attempted against a closed glottis or some other source of airway obstruction.

12 How is laryngospasm treated?

The treatment for laryngospasm is to support ventilation. Call for an assistant, provide a jaw thrust, and assist the patient’s inspiratory efforts with positive-pressure ventilation, using 100% oxygen. If this proves unsatisfactory, administer succinylcholine, 0.15 to 0.30 mg/kg (about 10 to 20 mg in adults), to relax the vocal cords. (I have had success with even 5 mg of succinylcholine administered intravenously to an adult—in this setting a little seems to go a long way; another advantage is that the diaphragm and accessory muscles of respiration remain functional.) If the patient continues to experience difficulty with ventilation, reintubation after administering approximately 100 mg of succinylcholine may be necessary. Once intubation is completed and end-tidal CO2 has been verified, the patient should receive assisted ventilation. Sedation may be appropriate. When re-extubation is attempted, be prepared for a possible recurrence of laryngospasm. If stridorous breath sounds are caused by laryngeal edema, administration of nebulized racemic epinephrine and intravenous steroids may be indicated.

13 The laryngospasm resolves. Chest auscultation reveals bilateral rales. What is the most likely cause?

Although congestive heart failure, fluid overload, adult respiratory distress syndrome, and aspiration of gastric contents need to be considered, negative-pressure pulmonary edema (NPPE) is the likely cause. NPPE results from generation of negative intrapleural pressures when the patient inspires against a closed or obstructed glottis. Whereas intrapleural pressures vary between negative 5 and negative 10 cm H2O during a normal respiratory cycle, inspiration against a closed glottis may generate between ˜negative 50 and ˜negative 100 cm H2O pressure. Such increased pressures increase venous return to the thorax and pulmonary vasculature, increasing transcapillary hydrostatic pressure gradients, producing pulmonary edema. The onset of edema has been noted from 3 to 150 minutes after the inciting event. Some authorities refer to this syndrome as negative-pressure pulmonary injury (NPPI) because pink or frankly bloody pulmonary secretions suggest that some alveolar injury has taken place during attempts to breathe against a closed glottis.

14 How is negative-pressure pulmonary edema treated?

Once the airway obstruction is relieved, treatment is supportive. The pulmonary edema usually resolves between 12 and 24 hours. Continue oxygen therapy; continuous positive airway pressure and mechanical ventilation with positive end-expiratory pressure may occasionally be needed, depending on the severity of gas exchange impairment. Diuretics should be administered only if the patient has intravascular fluid overload or perhaps in the most severe cases.

KEY POINTS: Postanesthetic Care and Complications image

1. Postanesthetic care is part of the continuum of perioperative care and the responsibility of the anesthesiologist.
2. Adequate oxygenation, postoperative pain, and PONV are common problems that delay PACU discharge.

15 Describe an approach to the evaluation of postoperative hypertension and tachycardia

A hyperdynamic postoperative phase is not an uncommon event. Frequently observed and readily treatable causes include pain, hypoventilation, hypercarbia, hypothermia with shivering, bladder distention, and essential hypertension. Also consider hypoxemia, hyperthermia and its causes, anemia, hypoglycemia, tachydysrhythmias, withdrawal (e.g., drug and alcohol), myocardial ischemia, prior medications administered, and coexisting disease. Rarely the hyperdynamic state may reflect hyperthyroidism, pheochromocytoma, or malignant hyperthermia.

16 What might cause hypotension in the postoperative phase?

Prior or ongoing blood loss, third-space sequestration of fluid, and inadequate volume replacement manifest as hypotension. Myocardial ischemia or heart failure may present as hypotension, as can sepsis or anaphylaxis.

17 How should hypotension be treated?

Consider the surgical procedure, intraoperative events, medications, and past medical history. Evaluate blood loss and urine output. Review the ECG rhythm strip and consider a 12-lead ECG. Volume expansion with balanced crystalloid solutions is first-line therapy. Elevation of legs and Trendelenburg positioning may help transiently. Circumstances may require administration of colloid or packed red blood cells. Should volume expansion prove unsatisfactory, vasopressors or inotropes may be necessary, but these suggest the need for further evaluation.

18 Under what circumstances is a patient slow to awaken?

A reasonable initial assumption is that such patients are displaying residual drug effects. Should decreased awareness persist beyond a reasonable period of observation, ventilatory, metabolic, and central nervous system (CNS) etiologies must be considered. Does the patient have a seizure history and is the patient currently postictal? CNS ischemia caused by decreased perfusion or embolic phenomena should be considered. Has the patient had documented CNS ischemic events or strokes? Laboratory analysis should include arterial blood gases as well as measurements of serum sodium and glucose. Should these be normal, perhaps a computed tomography of the brain is needed.

19 Discuss the issues surrounding postoperative nausea and vomiting

PONV remains a significant, troublesome postanesthetic problem. It results in delayed PACU discharge and occasional unplanned hospital admissions and is a recurring cause of patient dissatisfaction. Both the surgical procedure and anesthetic agents administered may increase PONV risk. Procedural risks include laparoscopic surgery; surgery on genitalia; craniotomies; and shoulder, middle ear, or eye muscle procedures. Patient factors are female sex, nonsmoker, prior PONV or motion sickness history, and school-age children. Anesthetic agents with a high association with PONV include the opioids, volatile inhalation agents, and nitrous oxide. Propofol has the lowest incidence of any of the induction agents and has been used effectively as a rescue medication. Risk assessment should be made on the basis of these factors, and prophylactic treatment or alteration of the anesthetic plan determined by evidence of efficacy. PONV rescue (treatment once PONV has ensued) requires balancing drug benefits with side effects and cost.

20 Should ambulatory patients be treated differently in the postanesthetic care unit?

The goal of postanesthetic care of the ambulatory patient is to render the patient street ready. Pain should be treated with short-acting agents such as fentanyl. Nonnarcotic analgesia and nerve blocks should be used whenever possible. Oral analgesics should be used in phase 2 recovery as prescribed for postoperative care. After regional anesthesia, extremities should be protected while the patient is mobilized, and ambulation should be assisted if transient segmental paresthesia makes movement unsteady. No ambulatory surgery patient should be discharged after receiving any sedating medication without a companion to ensure safe transportation to a place of residence.

21 Should patients be required to tolerate oral intake before postanesthetic care unit discharge?

Taking clear liquids before discharge can increase length of stay in the PACU. It is unclear if the ability to tolerate clear liquids decreases adverse outcomes and at present time is not recommended to be a requirement for PACU discharge. However, it may be helpful in selected patients.

22 A patient has undergone a general anesthetic for an outpatient procedure. Recovery has been uneventful, yet the patient has no ride home. How should this be handled?

Patients should be required to have a responsible party accompany them home after anesthesia. It has been shown to decrease adverse events. The responsible party will be able to promptly report any adverse events that may arise. The patient in this case should be kept at the health care facility, possibly under 23-hour observation, or until a responsible party is available.

23 In designing a postanesthetic care unit for a new outpatient surgical center, the board of directors states that all patients should be kept in the postanesthetic care unit for at least 1 hour for recovery. Is this minimal postanesthetic care unit stay reasonable?

Although this time may be reasonable, the American Society of Anesthesiologists has no recommendation for the minimal length of stay in the PACU. Length of stay should be determined on a case-by-case basis. A discharge protocol should be designed that allows patients to reach postoperative goals that will direct them toward discharge.

Website image

http://www.asahq.org/

SUGGESTED READINGS

1. ASA Task Force on Post Anesthesia Care. Practice guidelines for postanesthesia care. Anesthesiology. 2002;96:742-752.

2. Feeley T.W., Macario A. The postanesthetic care unit. In: Miller R.D., editor. Miller’s anesthesia. ed 6. Philadelphia: Elsevier Churchill Livingstone; 2005:2701-2728.

3. Gan T.J., Meyer T., Apfel C.C., et al. Consensus guidelines for managing postoperative nausea and vomiting. Anesth Analg. 2003;96:62-71.

Related posts:

31: Temperature Disturbances 61: High-Risk Obstetrics 46: Malignant Hyperthermia and Other Motor Diseases 5: Electrolytes 76: Electroconvulsive Therapy 41: Acute Respiratory Distress Syndrome (ARDS)