CEN Adult Medical Pearls: Neuro, GI and Respiratory Look-alikes

In depth

The one-page summary above is what the PDF prints. These sections go further.

Anticholinergic delirium and the Beers Criteria

The 2023 AGS Beers Criteria list brompheniramine, chlorpheniramine, cyproheptadine, dimenhydrinate, oral diphenhydramine, doxylamine, hydroxyzine, meclizine, promethazine and triprolidine as first-generation antihistamines to avoid in older adults (moderate evidence, strong recommendation). They are highly anticholinergic, their clearance falls with age, tolerance develops when they are used for sleep, and they cause confusion and falls. Diphenhydramine for a severe allergic reaction may still be appropriate. Many over-the-counter "PM" products contain diphenhydramine or doxylamine, so discharge teaching includes label reading. A replacement hypnotic from the same class keeps the delirium going; the nurse questions that order.

The drug-disease table adds that patients with or at high risk of delirium should avoid anticholinergics, antipsychotics, benzodiazepines, oral and parenteral corticosteroids, H2-receptor antagonists, nonbenzodiazepine Z-drugs and opioids, except in the situations the criterion names, because they can induce or worsen delirium. Urinary retention and constipation from anticholinergics feed the delirium too, which is why a bladder scan is a sensible order.

Valproate and ammonia

The Depakote label (revised 3/2026) warns that hyperammonemia may occur despite normal liver function tests. In a patient on valproate who develops unexplained lethargy, vomiting or a change in mental status, hyperammonemic encephalopathy should be considered and an ammonia level measured. If ammonia is increased, valproate is stopped and treatment for hyperammonemia begins; asymptomatic elevations are more common and need close monitoring. Valproate is contraindicated in known urea cycle disorders, and unexplained hyperammonemic encephalopathy prompts evaluation for one. Concomitant topiramate has been associated with hyperammonemia with or without encephalopathy, and the label says this is not a pharmacokinetic interaction, so a therapeutic valproate level does not exclude it. The boxed warning on fatal hepatic failure is a separate problem, monitored with liver tests before and during therapy.

Myasthenia gravis at the bedside

Merck (May 2026): myasthenia causes episodic weakness and easy fatigability; ptosis, diplopia and weakness after use of the affected muscle are the commonest symptoms. In the ice pack test an ice pack is held on the closed eyes for 2 minutes and removed; full or partial resolution of ptosis is positive, with a sensitivity of perhaps 80%. It usually does not work when ophthalmoparesis is present; then a rest test is used (lying quietly in a dark room with eyes closed for 5 minutes). Edrophonium testing is no longer routine and the drug is no longer available in the United States. Bedside tests do not make the diagnosis alone: acetylcholine receptor antibodies are found in 80 to 90% of generalized but only about 50% of ocular cases, and EMG adds to them.

Behbehani (2023) calls fatigability the hallmark, notes that the lid elevator fatigues with sustained upgaze, and that the pupils are not involved in myasthenia, so testing them helps. A dilated, sluggish pupil with ptosis and diplopia suggests a third nerve palsy, which in classic teaching needs urgent imaging for a compressive lesion such as an aneurysm. Ocular myasthenia converts to generalized disease in about 20 to 60% of cases. Bulbar or respiratory weakness is managed on Myasthenic Crisis and Guillain-Barré Syndrome.

Lumbar puncture: position and aftercare

Merck (How To Do Lumbar Puncture, Feb 2026): the lateral decubitus position is generally preferred and must be used if manometry is wanted, because opening pressure cannot be measured sitting; normal opening pressure is 7 to 18 cm CSF. Sitting and leaning forward helps when landmarks are hard to feel, as in obesity. Bed rest afterward is not needed and does not reduce post-puncture headache, which affects about 10%, usually within hours to a day or two, most often in young people of small body mass; neither the volume removed nor lying down prevents it, and lying down may help a headache that has started. Narrower needles reduce it. Strenuous exercise is probably avoided for 24 hours.

Spinal epidural hematoma is the complication not to miss. Risk rises with coagulopathy (INR above 1.5, therapeutic anticoagulation, platelets below 50,000/mcL or a raised aPTT). Patients are taught to report persistent or worsening back pain, which can appear up to several days later and needs prompt evaluation. CT before LP, CSF patterns and meningitis care are on Meningitis and Encephalitis.

Antiplatelet drugs and traumatic intracranial bleeding

The Plavix label: the active metabolite binds the platelet P2Y12 ADP receptor irreversibly, so exposed platelets are affected for the rest of their lifespan, about 7 to 10 days. The metabolite's half-life is about 30 minutes and clopidogrel's about 6 hours; platelet aggregation returns to baseline about 5 days after the drug is stopped, as new platelets replace old ones. Aspirin also inactivates platelets permanently. A platelet count therefore measures number, not function. The label notes that transfused platelets may be less effective within 4 hours of a loading dose or 2 hours of a maintenance dose.

Transfusion is not a routine reversal. In PATCH (2016), platelet transfusion after spontaneous intracerebral hemorrhage on antiplatelet therapy appeared inferior to standard care. The 2026 NCS/SCCM focused update conditionally advises avoiding platelet transfusion in non-neurosurgical patients with spontaneous intraparenchymal hemorrhage on antiplatelets, advises it for patients on aspirin undergoing surgery, and makes no recommendation for traumatic intracranial hemorrhage or for desmopressin (abstract read). For the ED nurse the point is to treat the patient as antiplatelet-affected during neurologic checks, blood pressure control and repeat imaging. Merck notes chronic subdural hematomas are more common in older patients on antiplatelet or anticoagulant drugs. Head injury priorities are on Trauma: Primary and Secondary Survey and Neuro: ICP and Stroke.

Open depressed skull fractures

Brain Trauma Foundation surgical guidelines (Bullock 2006, abstract read): open (compound) fractures depressed more than the thickness of the cranium should be operated on early, by elevation and debridement, to reduce infection, and every management plan for an open depressed fracture includes antibiotics. Nonoperative care is an option only when there is no evidence of dural penetration, significant intracranial hematoma, depression over 1 cm, frontal sinus involvement, gross cosmetic deformity, wound infection, pneumocephalus or gross contamination. Closed depressed fractures may be managed without surgery. Merck adds that depressed fractures sometimes need elevation and open fractures may need debridement.

In the ED the wound gets a sterile dressing and oozing is controlled at the edges without pressing on the fragment (classic teaching). CDC tetanus guidance: for dirty or major wounds, a booster is given when the last dose was 5 or more years ago (10 years for clean, minor wounds), and tetanus immune globulin 250 units IM is added for dirty wounds when the series is unknown or incomplete, or the patient has HIV or severe immunodeficiency.

Meningococcal chemoprophylaxis

CDC Surveillance Manual (Oct 2024): close contacts, meaning household members, childcare contacts and anyone directly exposed to the patient's oral secretions in the 7 days before onset, receive chemoprophylaxis regardless of vaccination status, as soon as possible because risk is highest in the first few days; more than 14 days after onset it is probably of limited or no benefit. Health care staff qualify only after airway management or respiratory secretion exposure. Regimens: rifampin 10 mg/kg (max 600 mg) every 12 hours for 2 days; ceftriaxone 250 mg IM once at 15 years and older (125 mg under 15); ciprofloxacin 20 mg/kg (max 500 mg) once, only where fluoroquinolone resistance has not been found; azithromycin is not routine. Rifampin and ciprofloxacin are marked not recommended for pregnant women; rifampin also interferes with oral contraceptives and some seizure and anticoagulant drugs.

The ceftriaxone label reports no embryotoxicity or teratogenicity in mice, rats or primates and advises use in pregnancy only if clearly needed. IM doses may be reconstituted with 1% lidocaine and injected deep into a large muscle; lidocaine-containing solutions are never given IV. Teach the contact to seek care at once for fever, headache or rash.

Food impaction and eosinophilic esophagitis

Merck (Esophageal Foreign Bodies, Apr 2025): food is the commonest esophageal foreign body. A patient who hypersalivates and cannot swallow secretions has complete obstruction and needs endoscopy; oral contrast studies are avoided because of aspiration risk and because residual contrast hampers endoscopy. Glucagon relaxes the distal esophagus but does not seem particularly effective. Impactions lodge where the lumen is narrowed, by strictures or eosinophilic esophagitis, so follow-up evaluation for structural and functional abnormalities is recommended.

Merck (Eosinophilic Esophagitis, Feb 2026): onset is from infancy to young adulthood, more often in males, frequently with asthma, atopic dermatitis or allergic rhinitis. In adolescents and adults, food impaction and dysphagia are the commonest symptoms. Diagnosis is endoscopy with biopsy showing 15 or more eosinophils per high-power field; the esophagus can look normal, so biopsies are essential, and taking them during the endoscopy that clears the bolus avoids a second procedure. Adult treatment starts with a proton pump inhibitor or topical glucocorticoid (fluticasone or budesonide); dupilumab, elimination diets and careful dilation of strictures follow.

Acalculous cholecystitis

Merck (Acute Cholecystitis, Oct 2025) names major surgery or critical illness and prolonged fasting or parenteral nutrition (bile stasis) as risk factors, with immune deficiency, vasculitis, diabetes and atherosclerosis. Morgan (2025) adds sepsis, severe trauma, burns and mechanical ventilation, gives mortality above 30% with gangrene in up to half of resected gallbladders and perforation in over 10%, and warns that the sonographic Murphy sign is unreliable in sedated or confused patients. Ultrasound findings include wall thickening over 3 mm, distension over 8 cm long or 5 cm wide and pericholecystic fluid. Merck cautions that sludge and a thick wall without pericholecystic fluid can reflect critical illness alone, and calls cholescintigraphy the most reliable test.

Treatment: blood cultures and parenteral antibiotics start, but antibiotics are not the whole treatment: the gallbladder needs source control. Percutaneous cholecystostomy is the option for very high surgical risk patients with acalculous disease (Merck) and can be definitive, with recurrence usually under 10% after tube removal (Morgan); early cholecystectomy is favored in patients at low surgical risk (Merck). Fever in a ventilated boarder is not automatically pneumonia when the right upper quadrant is tender.

Grey Turner and Cullen signs

Merck (Acute Pancreatitis, Aug 2026): flank ecchymosis (Grey Turner) and periumbilical ecchymosis (Cullen) occur in under 3% of cases, indicate extravasation of hemorrhagic exudate and portend a poor prognosis; pseudoaneurysm is among the local complications. Fluids start with lactated Ringer's at 1.5 mL/kg/h plus a 10 mL/kg bolus if hypovolemic, reassessed often, with adequacy judged by vital signs, urine output and a falling hematocrit and BUN. A large hematocrit drop with tachycardia, falling pressure and oliguria is not dilution: the nurse reports it at once, increases monitoring, and expects blood work, crossmatch, imaging and a question about anticoagulant prophylaxis. Pancreatitis care is on GI Bleeding, Liver Failure and Pancreatitis.

Sump tubes on suction

Open RN: a Salem sump is a large-bore double-lumen tube for gastric decompression; one lumen drains, the other admits a continuous flow of air that reduces negative pressure and keeps gastric mucosa from being drawn into the catheter, and an anti-reflux valve keeps secretions out of the vent. Without that airflow the tube works as a single lumen and the mucosa can be drawn against the ports, so drainage falls (the reasoning follows from the purpose of the vent; Open RN does not describe a capped vent). Merck describes the second lumen as venting to atmosphere and advises low, intermittent suction because continuous suction on one area causes ulceration and bleeding. Placement is confirmed by x-ray; Open RN says air auscultation is unreliable and should not be used. Drainage amount and color are documented every shift. Obstruction care is on Acute Abdomen and GI Surgical Emergencies.

Pneumonia after influenza, in older adults, and lung abscess

Merck (Community-Acquired Pneumonia, Sept 2026): influenza often predisposes to secondary bacterial pneumonia, with about threefold the mortality of influenza alone. Cavitation suggests S. aureus, anaerobes, fungi or mycobacteria; S. aureus including MRSA causes necrotizing pneumonia. MRSA risk factors include colonization or prior infection, recent hospitalization or antibiotics, immunosuppression, and necrotizing or cavitary pneumonia, recent influenza or empyema; hospitalized patients with them get linezolid or vancomycin added. ATS/IDSA 2019 notes bacterial pneumonia can occur with influenza or later, and that MRSA therapy can generally be withheld when the nasal swab is negative and de-escalated when cultures are negative. First-hour antibiotics are on Sepsis and Septic Shock Bundle.

Older adults: Merck notes fever is frequently absent, confusion or obtundation may be the main presentation, and delirium is present in about 20% and raises mortality. Diagnosis rests on the clinical picture and chest imaging. Tachypnea, a low saturation and focal crackles point to the lungs even when staff report no cough; bacteriuria in an older adult with delirium and no urinary signs is not treated as the cause (see CEN: Genitourinary, Gynecologic and Early-Pregnancy Emergencies).

Merck (Lung Abscess, Mar 2025): most follow aspiration of oral secretions with poor oral hygiene or reduced consciousness from alcohol, drugs or sedation. Anaerobic abscesses evolve over weeks to months with cough, fever, night sweats, weight loss and foul sputum; the classic film shows a single cavity with an air-fluid level in a dependent segment (posterior upper lobes, superior or basal lower lobes), whereas tuberculosis typically involves the apices, so airborne isolation stays until smears return. First-line is a beta-lactam/beta-lactamase inhibitor such as ampicillin-sulbactam; alternatives are a carbapenem or metronidazole plus ceftriaxone. Clindamycin is now rarely used because of C. difficile and resistance. Treatment usually lasts 3 to 6 weeks or longer, until imaging clears; drainage or surgery is for abscesses that do not respond. ATS/IDSA 2019 suggests no routine anaerobic coverage for aspiration pneumonia unless lung abscess or empyema is suspected.