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(Norcuron). Therefore, the quality of reversal depends on the class, amount of muscle recovery, and class of paralytic agent used. Choice B is incorrect because Sugammadex cannot reverse benzylisoquinolinium relaxants such as cisatracurium (Nimbex). Choice E is the correct answer here. Dosages to reverse rocuronium (Zemuron) are based on actual body weight and recovery at the motor end plate. For example, if two or more twitch responses to stimulation are present, 2 mg/kg of actual body weight is given. A higher dose, 4 mg/kg is needed if post tetanic stimulation is needed to produce a twitch response. For immediate reversal of rocuronium, 16 mg/kg is recommended. Train of four (TOF) monitoring is used to assess recovery from and depth of neuromuscular blockade. When using paralytic agents in the ICU, TOF monitoring should be used. Choice C, midazolam (Versed) is a benzodiazepine and can be reversed with flumazenil (Romazicon). Choice D, Ropivacaine (Naropin) is a local anesthetic and can be reversed with lipid emulsions in case of systemic toxicity.Answer: EDuvaldestin P, Kuizenga K, Saldien V, Claudius C, Servin F, Klein J, Debaene B, Heeringa M. A randomized, dose‐response study of sugammadex given for the reversal of deep rocuronium‐ or vecuronium‐induced neuromuscular blockade under sevoflurane anesthesia. Anesth Analg. 2010; 110(1):74–82.Hunter JM. Reversal of residual neuromuscular block: complications associated with perioperative management of muscle relaxation. Br J Anaesth. 2017; 119(suppl_1):i53–i62.

      12 A 75‐year‐old woman is admitted to the ICU after axillary to bifemoral bypass. Patient complains of pain from anterior thigh to her toes and a quadratus lumborum block is performed. What is the most serious complication of this procedure?HypertensionPostdural puncture headacheHyperemia of the legNumbness of the lumbar dermatomesRetroperitoneal hematomaBecause the quadratus lumborum block (QL) is a deep block, complications to watch out for include direct injury to the kidney, lumbar arteries, leading to retroperitoneal hematoma and pleural penetration leading to pneumothorax (choice E). A prolonged motor block may result from anesthetic distribution to the lumbar plexus. Hypotension, which can result from the spread of local anesthetic to the paravertebral space, has also been described (choice A). Local anesthetic toxicity (LAST) is always a potential risk of any peripheral or neuraxial technique. Rupture of the dura mater causing postdural puncture headache is a complication of an epidural catheter placement (wet tap) and not a complication of QL block (choice B). Numbness of the lumbar dermatomes (choice D) is the desired effect and hyperemia of the leg is transient and not a complication (choice C) (Figure 12.1).Figure 12.1 Quadratus lumborum block. QL: quadratus lumborum; EO: external oblique; IO: internal oblique; TA: transverse abdominis; K: kidney; P: psoas major; LD: latissimus dorsi; IL: iliocostalis lumborum; Lo: longissimus; Mu: multifidus.Answer: EElsharkawy H, El‐Boghdadly K, Barrington M. Quadratus lumborum block: anatomical concepts, mechanisms, and techniques. Anesthesiology. 2019; 130(2):322–335.Krohg A, Ullensvang K, Rosseland LA, Langesæter E, Sauter AR. The analgesic effect of ultrasound‐guided quadratus lumborum block after cesarean delivery: a randomized clinical trial. Anesth Analg 2018; 126(2):559–565.Blanco R, Ansari T, Girgis E. Quadratus lumborum block for postoperative pain after caesarean section: A randomised controlled trial. Eur J Anaesthesiol. 2015; 32(11):812–8.

      13 A 60‐year‐old morbidly obese man with a difficult airway and obstructive sleep apnea was taken for emergent laparotomy for peritonitis. After awake fiberoptic intubation with benzocaine and induction of anesthesia, the oxygen saturation reads and remains 85% with good signal quality. His lips appear cyanotic, and he has bilateral breath sounds. Which of the following is the most likely cause?CarboxyhemoglobinemiaMethemoglobinemiaCyanide toxicityMain stem intubationHgb A1c level greater than 10%Acquired methemoglobinemia is potentially threatening and must be immediately recognized. The most common cause of methemoglobinemia is exposure to oxidizing agents such as benzocaine and nitroglycerine (choice B). When iron is ferrous oxidized to its ferric state, oxygen binding to hemoglobin is prevented which shifts the oxygen hemoglobin dissociation curve to the left. Excess methemoglobin leads to hypoxia, cyanosis, impaired aerobic respiration, and metabolic acidosis. Other etiologies are genetic deficiencies of cytochrome‐b5 and cytochrome‐b5 reductase. Unfortunately, pulse oximetry and arterial blood gases can be misleading in patients with methemoglobinemia. Co‐oximetry is the gold standard. Treatment options for methemoglobinemia include supportive measures, methylene blue, and vitamin C which are potent reducing agents. Methylene blue is contraindicated in G6PD deficiency.There are no triggering agents to cause Carboxyhemoglobinemia (i.e., Smoke inhalation with CO) and Cyanide toxicity (i.e., Smoke inhalation, Sodium Nitroprusside, Poisons) in this case which makes choices A and C unlikely. The patient is intubated fiber‐optically and has bilateral breath sounds which makes choice D unlikely. Choice E indicates untreated diabetes mellitus and is therefore incorrect.Answer: BGuay J . Methemoglobinemia related to local anesthetics: a summary of 242 episodes. Anesth Analg. 2009; 108(3):837.Anderson CM, Woodside KJ, Spencer TA, Hunter GC. Methemoglobinemia: An unusual cause of postoperative cyanosis. J Vasc Surg. 2004; 39(3):P686–690.

      14 Patient is a 70 kg, 60‐year‐old man undergoing paravertebral nerve block due to multiple rib fractures in the ICU. Patient is hemodynamically stable before the block; however, becomes hypotensive and tachycardic 15 minute after the procedure is finished. You are suspecting local anesthetics toxicity. What would be the most appropriate treatment at this time? Vasopressin bolus followed by infusionDiltiazem (Cardizem) 5 mg bolus followed by infusionLipid emulsion 20% 100 mL follow by infusionPropofol 100 mgLorazepam (Ativan) 2 mgLocal anesthetic systemic toxicity (LAST) can occur after inadvertent intravascular injection or increased vascular uptake of a local anesthetic (LA) agent. The mechanisms for the clinical responses seen are multifactorial, mostly affecting the central nervous and cardiovascular systems. Neurologic manifestations such as tinnitus, seizures, or confusion are most common but the cardiovascular effects can be devastating. LA medications accumulate in mitochondria and cardiac tissue with greater affinity relative to plasma and can manifest with profound shock and cardiac instability.LA exerts its action at voltage‐gated sodium channels, blocks calcium channels, and at higher concentrations inhibits other channels, enzymes, and receptors including the carnitine‐acylcarnitine translocase receptor in mitochondria. This is the basis for treatment of LAST with lipid emulsion. Bupivacaine is more likely to cause cardiovascular collapse because it is more lipophilic and has a greater affinity for the voltage‐gated sodium channels. Factors that increase the likelihood of toxicity are extremes of age, comorbidities, higher total dose of LA medication, and site of injection. The highest incidence of LAST is with paravertebral blocks.Treatment of LAST includes 20% lipid emulsion which acts as a “lipid sink.” Recommended dose is 100 mL over 2–3 minutes for patients at least 70 kg (1.5 mL/kg), followed by infusion of 250 mL over 20 minutes. The bolus can be repeated, and the infusion rate doubled if clinically not improved (choice C).Further care includes supportive measures such benzodiazepines for treatment of seizures. Lorazepam (Ativan) can be administered if the patient is showing signs of seizure activity (choice E). Beta‐blockers, calcium channel blockers (diltiazem), and vasopressin should be avoided (choices A and B). Epinephrine if needed should be administered at lower doses (less than 1 mg/kg). Propofol is not the best choice and can exacerbate hypotension (choice D).Answer: CNeal JM, Neal EJ, Weinberg GL. American Society of Regional Anesthesia and Pain Medicine Local Anesthetic Systemic Toxicity checklist: 2020 version. Reg Anesth Pain Med. 2020:rapm‐2020‐101986. doi: 10.1136/rapm‐2020‐101986. Epub ahead of print.El‐Boghdadly K, Pawa A, Chin KJ. Local anesthetic systemic toxicity: current perspectives. Local Reg Anesth. 2018; 11:35–44.

      15 A 65‐year‐old polytrauma patient in the ICU with blunt cerebrovascular injury and rib fractures has severe pain which affects patient's respiratory efforts. Patient has a new lower extremity venous thromboembolic event. You place a pain consult for possible epidural anesthesia. Considering your plan for a neuraxial block, which of the following therapies should be avoided?Ketorolac (Toradol) and subcutaneous heparinASAEnoxaparin (Lovenox)Heparin infusionAcetaminophen IV (Ofirmev)Because neuraxial techniques are increasingly used to manage pain in the ICU, intensivists need to understand the guidelines for management of anticoagulation as it affects the placement of epidural catheters. Serious complications associated with neuraxial anesthesia are epidural hematomas, epidural abscess, and nerve injuries. Absolute contraindications

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