Stanford University



PACU Pre and Post Testing: Answers 1: E -- excellent reference for discussion of answers. 2: C3: AFlumazenil antagonizes the effects of prior benzodiazepine administration (sedation, impaired recall, psychomotor slowing) but the degree and duration of this effect depends on the dose of benzodiazepine given. To achieve a controlled reversal, the recommended initial dose is 0.2 mg (2.0 ml) given IV over 15 seconds [88]. If the desired level of consciousness is not obtained after waiting an additional 45 seconds, injections can be repeated at 60 second intervals to a maximum dose of 1.0 mg. The titration method is recommended to control patient wakening to the endpoint desired. The administration of a single large bolus dose can result in confusion and agitation upon wakening.For management of known or suspected benzodiazepine overdose, administration of flumazenil should be titrated in the same manner. In the absence of a response to the initial 0.2 mg, larger increments (0.3 - 0.5 mg) can be injected slowly and at 1 minute intervals. Most patients with benzodiazepine overdose will respond to a cumulative dose of 1.0 - 3.0 mg of flumazenil. Doses beyond 3.0 mg do not reliably produce additional effects and failure to respond at these dosages suggests other etiologies of impaired consciousness.No clinical studies have been performed in children. Dosage requirements are not altered in renal failure patients and the elderly. Although the usual initial dose of flumazenil may be used in patients with liver dysfunction, subsequent doses should be reduced in amount or frequency.4: BSide effects of Ketamine include hypertension, diplopia and nystagmus, dizziness and confusion, cardiac arrhythmias, nausea and vomiting, and psychomimetic reactions. To review other opioid and nonopioid analgesic side effects please refer to:Paul White. “The Role of Non-Opioid Analgesic Techniques in the Management of Pain After Ambulatory Surgery”. Anesthesia and Analgesia 2002: 94: 577-584 5: CCorneal abrasions occur more frequently in elderly patients, after long cases, with lateral or prone positioning, and after head or neck surgery. 6: CPlease refer to ASA PACU guidelines and recommendations: (Table 3: Summary of Recommendations for Discharge)Requiring that patients urinate before discharge: The requirement for urination before discharge should not be part of a routine discharge protocol and may only be necessary for selected patients.Requiring that patients drink clear fluids without vomiting before discharge: The demonstrated ability to drink and retain clear fluids should not be part of a routine discharge protocol but may be appropriate for selected patients.Requiring that patients have a responsible individual accompany them home: As part of a discharge protocol, patients should routinely be required to have a responsible individual accompany them home.Requiring a minimum mandatory stay in recovery: A mandatory minimum stay should not be required. Patients should be observed until they are no longer at increased risk for cardiorespiratory depression.Discharge criteria should be designed to minimize the risk of central nervous system or cardiorespiratory depression after discharge.7: BPatients must be carefully evaluated to determine which level of post operative care is most appropriate. Triage should be based on clinical condition and the potential for complications that require intervention. Alternatives to PACU care must be employed in a non discriminatory fashion. Triage should not be based on age, ASA classification, ambulatory vs inpatient status, or type of insurance. A wide margin of safety and applicable PACU standards should be preserved when appropriate. 8: C Disadvantages of the intramuscular route include larger dose requirements, delayed onset, and unpredictable uptake in hypothermic patients. The risk of hematoma formation is also a consideration in anticoagulated patients.9: EEpidural opioid analgesia is effective after thoracic and abdominal procedures. It helps to wean patients with obesity or chronic obstructive pulmonary disease from mechanical ventilation.Immediate ventilator depression can occur due to vascular uptake. Delayed ventilatory depression can occur related to cephalad spread in cerebrospinal fluid. Nausea and pruritis are known side effects. Nausea resolves with antiemetics, whereas pruritis often responds to naloxone infusion. Epidural analgesia may also improve surgical outcomes after orthopedic and urologic procedures. Addition of local anesthetic or clonidine enhances analgesia and decreases the risk of side effect from epidural opioids. 10: BA blood pressure cuff that is too large yields a falsely low value. Hypothermic patients can sometimes experience hypotension during the rewarming phase. Postoperative myocardial ischemia is often initiated in high risk patients by tachycardia or hypotension. Hypotension caused by ischemic ventricular dysfunction can quickly cause irreversible infarction. Rarely, hypotension reflects steroid deficiency in patients in whom adrenal function is suppressed by exogenous steroid use. Furosemide therapy may precipitate hypotension by producing hypovolemia. 11: EA reduction in circulating intravascular volume is the definition of absolute hypovolemia. Relative hypovolemia is characterized by a normal intravascular volume. It may result from a decrease in endogenous sympathetic nervous system activity, as can occur with vasovagal stimulation or with blockade of the sympathetic nervous system. Impedance of venous return by compression of thoracic veins secondary to positive pressure ventilation or from compression of the vena cava by a gravid uterus also can result in decreased venous return. These are forms of relative hypovolemia. 12: AFactors that increase parasympathetic nervous system activity or decrease sympathetic nervous system activity reduce supraventricular pacemaker rates and promote sinus bradycardia. Frequently, this causes emergence of a nodal pacemaker in the lower atrioventricular node or the bundle of His. Nodal rhythms usually are benign unless a low ventricular rate or lack of coordinated atrial contraction reduces cardiac output and blood pressure. If hypotension occurs, atropine or beta-stimulating medications usually can restore sinus rhythm. Idioventricular bradycardia is life-threatening and seldom generates adequate cardiac output. Atropine will not increase ventricular pacemaker rates because the ventricle lacks significant parasympathetic nervous system innervations. Epinephrine, isoproterenol, and cardiac pacing will accelerate the ventricular rate. 13: DAn aberrant impulse arising in the atrium, atrioventricular node, or upper bundle of His generates an atrial premature contraction that typically has an early but otherwise normal QRS complex that often is not preceded by a P wave. In postoperative patients, atrial premature contractions usually appear with increased central nervous system activity and seldom cause hemodynamic compromise. If a supraventricular impulse enters the ventricular conduction system activity it seldom causes hemodynamic compromise. If a supraventricular impulse enters the ventricular conduction system where all pathways have recovered excitability, asynchronous ventricular depolarization will generate wide high-amplitude electrocardiogram complexes that are difficult to distinguish from true premature ventricular contractions. These aberrantly conducted premature supraventricular depolarizations are sometimes preceded by an abnormal P wave and often exhibits noncompensatory pause. The aberrant QRS complex often resembles normal complexes in general shape; increased sympathetic nervous system activity usually is responsible. 14: CCarbon monoxide reversibly binds to hemoglobin with 200 times the affinity of oxygen, thus creating carboxyhemoglobin, which impedes both the binding of oxygen and the dissociation of oxygen from oxyhemoglobin. The overall risk of exposure to carbon monoxide exposure is estimated at 0.26%, but the risk increases to 0.46% for the first cases of the days to 2.9% for first cases performed in peripheral anesthetizing locations. Symptoms of moderate carbon monoxide exposure such as headache, nausea, vomiting, irritability, and altered visual or motor skills are nonspecific and common during recovery. Carbon monoxide seldom causes cyanosis. A pulse oximeter interprets carboxyhemoglobin as oxyhemoglobin, The PaO2 is often high, although spO2 is low, and metabolic acidemia is significant. 15: B The incidence of hypoxemia in postoperative patients is high. In one study of PACU patients placed on room air, 30% of patients younger than 1 yo, 20% of those 1-3 years old, and 14% of those 3-14 years old, and 7.8% of adults had oxygen saturations fall to <90%. Perioperative hypoxemia occurs more frequently in children with respiratory infections or chronic adenotonsillar hypertrophy. Hypoxemia occurs frequently after regional anesthesia. Use of oxygen neither consistently prevents hypoxemia, nor addresses underlying causes. The cost of supplemental oxygen is minimal, the inconvenience to patients is minor, and the overall risk is small. 16: DInduction with barbiturate agents such as thiopental or methohexital seem less likely to cause postoperative nausea and vomiting than induction with etomidate or ketamine. Propofol appears to have the lowest overall incidence of postoperative nausea and vomiting and may possess an antiemetic effect. 17: BMany agents are useful for PONV in the PACU and work by various mechanisms. Using intravenous scopolamine as an antiemetic causes unacceptable psychogenic reactions during recovery. Although transdermal scopolamine may have some prophylactic benefit, its low efficacy and tendency to cause visual disturbances make it a poor substitute for other agents. It does have prolonged effects useful for postdischarge nausea and vomiting. Metoclopramide, ondansetron, ephedrine, and propofol all have been used effectively in the PACU setting. 18. BPerioperative oral or intravenous administration of COX 2 inhibitors offers adjuvant therapy to augment postoperative analgesia. Concerns about cardiac side effects have led to the withdrawal of rofecoxib and clouded the overall appropriateness of this approach. Ibuprofen and Tylenol are effective when given orally before surgery. The anti-platelet effect of toradol may decrease cardiac ischemic events in patients with coronary artery disease. Agonist-antagonist analgesia offer little advantage. The use of clonidine to supplement analgesia is effective but can be limited by hypotension. 19: A (1,2, and 3 are) indications for treatment of postoperative hypotension include a systolic or diastolic pressure 20-30% above baseline, OR signs or symptoms of complications (headache, bleeding, ocular changes, angina, ST segment depression), or an unusual risk of morbidity (increased intracranial pressure, mitral regurgitation, open eye injury). 20: E (all of the above). In the PACU, metabolic rate and CO2 production can be increased by as much as 40%. Shivering, high work of breathing, infection, sympathetic nervous system activity, and rapid carbohydrate metabolism during intravenous hyperalimentation also accelerate CO2 production. Malignant hyperthermia generates CO2 production many times greater than normal. ................
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