An 88-year-old male with a 55 pack-year smoking history and an additional past medical history of COPD, and stage IA non–small cell lung cancer was referred for bronchoscopy. Prior to the procedure the patient was alert and oriented, afebrile, with BP 130/70, RR 14, and O2 saturation of 99% while breathing room air. The patient received a total of 100 µg IV fentanyl and 4 mg IV midazolam in divided doses during the bronchoscopy. Following the airway survey the diagnostic bronchoscope was removed and the patient received an additional 100 µg of fentanyl and 1 mg of midazolam prior to insertion of the scope for endobronchial ultrasound. Two minutes after insertion of the endobronchial ultrasound bronchoscope the patient developed a clenched hand and jaw and hypertension to 225/135 mm Hg. Respiratory motion was no longer evident upon examination of his chest wall. Oxygen saturation dropped to 81%. In addition to securing the airway the next most appropriate step would be:
Correct Answer: C
This patient has likely experienced fentanyl-induced chest wall rigidity. Skeletal muscle rigidity following opiate administration, which may primarily affect the musculature of the chest and abdomen, was first described in 1953. While a rare complication of opioid analgesia, it is thought to be more commonly associated the lipophilic synthetic opioids such as fentanyl, remifentanil, and sufentanil. Risk factors include extremes of age, concurrent use of medications that alter dopamine levels, and higher doses or rapidity of injection. Skeletal muscle rigidity decreases the compliance of the chest wall and increases work of breathing or may even lead to the cessation of spontaneous breathing. Decreased chest wall compliance can also complicate efforts at mechanical ventilation. Treatment includes reversal of opioids with naloxone (answer C) or mechanical ventilation and neuromuscular blocking agents.
Head CT would be an appropriate diagnostic tool in cases of suspected stroke, but in this case the temporal association with fentanyl administration and the cessation of chest wall motion make rigidity the more likely diagnosis.
The patient developed acute hypertension along with atypical motion of the hand and arm which may suggest the possibility of hypertensive emergency. Acute therapy of hypertensive emergency is aimed at lowering of blood pressure by 10% to 20% but, in this case, the hypertension is secondary to respiratory distress.
Benztropine is indicated for therapy of dystonic reactions such as those associated with the administration of antipsychotic medications but is not the appropriate choice for the primary diagnosis here.
References:
A 65-year-old female is scheduled for spinal surgery. Her pre-op CXR is shown below. She has a past medical history of CAD and HTN, atrial fibrillation. Which of the following is most helpful in predicting her risk of postoperative of respiratory failure?
Correct Answer: A
As indicated by the CXR the patient suffers from severe kyphoscoliosis. Kyphosis refers to an excessive curvature of the thoracic spine. The prevalence of kyphosis increases with age due to the combined effects of vertebral fractures, muscle weakness, and degenerative disk disease. The increased curvature leads to a restrictive deficit on pulmonary function testing with decreased TLC and FVC. The restrictive deficit can be associated with atelectasis, intrapulmonary shunt, and arterial hypoxemia. It also places patients at greater risk of postoperative pulmonary complications including respiratory failure and need for mechanical ventilation. Patients with a vital capacity <35% of predicted are at increased risk and will frequently require postoperative ventilation. Atrial fibrillation has a small effect on risk of overall mortality but is not known to specifically increase risk of respiratory failure. In general, orthopedic surgery is associated with a lower complication rate than other procedures. Age >70 is associated with increased mortality in orthopedic patients but this patient is 65.
A 49-year-old female is admitted to the hospital with communityacquired pneumonia. On presentation to the emergency department she is complaining of shortness of breath:
CXR shows an RML lobar infiltrate. She is admitted to the general medical floor but that night complains of increased dyspnea that is worse when lying supine. She is noted to have a weak cough and difficulty clearing secretions. She is afebrile, with a pulse of 110 and BP 110/75. O2 sat remains >95% on 2 to 4 L/min NC. Exam is notable for a regular cardiac rhythm, with no murmurs, rubs, or gallops. There are bronchial breath sounds noted over the right mid-lung zone. Peripheral pulses are intact, strength is normal in the b/l upper and lower extremities and there are normal deep tendon reflexes. CXR is unchanged from admission.
Which will be most helpful in determining subsequent therapy and need for intubation?
Correct Answer: B
This patient is presenting with signs and symptoms consistent with myasthenic crisis. Myasthenic crisis can be the first presentation of myasthenia gravis, an autoimmune disorder caused by development of autoantibodies which attack the neuromuscular junction. Common precipitants of crisis in patients with myasthenia include infection, with bacterial pneumonia being most common, and drugs including fluoroquinolones. Clinical features include bulbar weakness and dysphagia, dyspnea, respiratory muscle weakness (often manifested as worsening respiratory function when supine—a position in which the abdominal contents impede the motion of the diaphragm more so than in the upright position), and decreased vital capacity. Elective intubation should be considered when vital capacity declines below 15 to 20 mL/kg. Additional therapies for myasthenic crisis include plasma exchange and IVIG. Myasthenia can be associated with generalized weakness, but a proportion of patients will present with primarily respiratory weakness. Lumbar puncture and EMG can be helpful in the diagnosis of GuillainBarre syndrome but weakness in the Guillain-Barre syndrome typically starts in the legs and is associated with a lack of deep tendon reflexes. Heart failure and subsequent pulmonary edema can lead to worsening dyspnea when lying flat. BNP and TTE can be helpful in making that diagnosis, but the normal cardiac exam and unchanged CXR make that diagnosis less likely here. Heart failure would also not explain the dysphagia. Chest CT could be helpful in establishing a diagnosis of aspiration, which occurs in the setting of bulbar weakness, but in this case the CXR is unchanged and there is minimal change in the degree of hypoxemia.
A 77-year-old male presented to the emergency department after motor vehicle accident. On arrival, respirations were shallow and the right chest appeared to move inward with inspiration. O2 saturation was 85% while breathing room air and pulse was 122. Chest x-ray and chest CT are shown in the figure below.
What is the next most appropriate step in management?
The patient has suffered significant thoracic trauma as the result of a motor vehicle collision. He has multiple right-sided rib fractures on CXR and flail chest on exam. In addition, the chest CT scan reveals significant pulmonary contusion and atelectasis. Management of flail chest includes pain control, management of pulmonary injury, and, in selected patients, surgical fixation. Importantly, this patient presents in respiratory distress with evidence of pulmonary contusion on chest CT. There are small trials of noninvasive ventilation in chest injury, but in this patient with distress and established lung injury this would not be appropriate. In addition, IV analgesia carries the risk of respiratory depression. Locoregional (epidural, paravertebral) analgesia is often preferred. There is increasing interest in surgical fixation of flail chest, but in patients with underlying contusion there is no benefit over nonoperative management. Epidural catheter placement can be a key component of pain control in flail chest but does nothing to treat the pulmonary contusion which is likely a larger risk factor for mortality.
A 68-year-male is in the midst of a prolonged ICU stay for respiratory failure, ARDS, and gram-negative bacteremia. He initially presented with shock requiring high-dose vasopressors and stress-dose steroids as well as severe hypoxemia requiring mechanical ventilation and paralytics. By ICU day 10 he has repeatedly failed spontaneous breathing trials with low tidal volumes. His exam is notable for reduced strength in b/l upper and lower extremities without rigidity. Laboratory studies including creatine kinase are within normal limits. Head CT is normal and CSF studies are normal. Electrophysiologic testing is notable for significantly decreased sensory and motor nerve amplitudes in multiple nerves, prolonged compound muscle action potentials, and decreased motor amplitudes.
Which of the following is an appropriate next step in management?
This patient is likely suffering from critical illness polyneuropathy and myopathy (CIP/CIM). CIP/CIM is a form of generalized weakness that results from skeletal muscle dysfunction and peripheral neuropathy. Risk factors include prolonged ICU stay, sepsis, use of steroids and neuromuscular blocking agents, and hyperglycemia during ICU stay. The etiology of CIP/CIM is not entirely understood, but it is thought to result from some combination of nerve ischemia, decreased muscle protein synthesis, disordered inflammatory signaling. Typical clinical features include failure to wean from mechanical ventilation, peripheral limb weakness, and the described features on electrodiagnostic testing. Patients with CIP/CIM can experience prolonged weakness and resolution, if it occurs, typically occurs over weeks to months. Treatment is primarily supportive with aggressive physical therapy and potentially prolonged mechanical ventilation. The differential diagnosis of CIP/CIM includes rare neuromuscular disorders such as the Guillain-Barre syndrome (GBS), but GBS more typically presents with an elevated CSF protein (with normal CSF cell count). Plasma exchange and IVIG are used in GBS and myasthenic crisis associated with Myasthenia Gravis, but there is no role for either in CIP/CIM. Dantrolene has been used in neuroleptic malignant syndrome (NMS), but in this case there is no mention of the use of neuroleptics nor is there fever of rigidity on exam.
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