# Clinical Cases: ICU Nutrition and Sedation

## Case 1: Refeeding Syndrome in a Malnourished Patient

### Clinical Image
![ECG showing prolonged QT interval associated with electrolyte disturbances](case_01_image.jpg)
*Source: [Wikimedia Commons - Electrocardiogram](https://commons.wikimedia.org/wiki/Category:Electrocardiograms) - Public Domain*

### Case Presentation
A 45-year-old woman with chronic alcohol use disorder is admitted to the ICU after being found unresponsive. She weighs 42 kg with BMI of 15.8 kg/m2, appearing severely malnourished with temporal wasting and loss of subcutaneous fat. Her NUTRIC score is 7 (high nutritional risk). After initial stabilization, the nutrition support team initiates enteral feeding via nasogastric tube at 25 mL/hour of a standard polymeric formula. On day 2, she develops confusion, tremor, and new-onset atrial fibrillation. Labs reveal phosphorus of 0.8 mg/dL (critically low), potassium 2.9 mEq/L, and magnesium 1.1 mg/dL. ECG shows prolonged QTc of 520 ms. The team recognizes refeeding syndrome and immediately holds tube feeds, administers IV phosphorus replacement (30 mmol over 6 hours), potassium chloride 40 mEq IV, magnesium sulfate 2 g IV, and thiamine 200 mg IV. After electrolyte correction over 24 hours, feeding is restarted at 10 kcal/kg/day (approximately 420 kcal/day) with close electrolyte monitoring every 6 hours. Feeds are advanced by 5 kcal/kg/day every 2-3 days as tolerated. She recovers without cardiac complications and is eventually advanced to goal nutrition over 10 days.

### Key Learning Points
- Refeeding syndrome risk factors include BMI less than 16, weight loss greater than 15% in 3-6 months, minimal intake for greater than 10 days, and history of alcohol abuse or chronic malnutrition
- The mechanism involves insulin release with carbohydrate refeeding causing intracellular shift of phosphorus, potassium, and magnesium, leading to dangerous hypophosphatemia
- Prevention requires identifying at-risk patients, starting feeds at low rates (10-20 kcal/kg/day), supplementing thiamine before carbohydrates, and monitoring electrolytes closely during advancement
- Cardiac arrhythmias from electrolyte disturbances (particularly hypomagnesemia and hypokalemia causing QT prolongation) are the most common cause of death

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## Case 2: Delirium and Sedation Management

### Clinical Image
![ICU patient with monitoring equipment demonstrating sedation assessment](case_02_image.jpg)
*Source: [Wikimedia Commons - Intensive Care Unit](https://commons.wikimedia.org/wiki/Category:Intensive_care_units) - CC BY-SA 4.0*

### Case Presentation
A 72-year-old man with COPD is intubated for hypercapnic respiratory failure. He is initially sedated with midazolam infusion at 4 mg/hour and fentanyl at 100 mcg/hour, maintaining RASS of -4 (deep sedation). On day 3, the team attempts to lighten sedation for a spontaneous awakening trial (SAT), but the patient becomes severely agitated (RASS +3), pulling at lines and attempting to self-extubate. Midazolam is restarted at 6 mg/hour. On day 5, despite adequate analgesia, he remains deeply sedated even 6 hours after holding midazolam, and when he does awaken, he is confused with fluctuating attention. CAM-ICU is positive for delirium. The team transitions sedation from midazolam to dexmedetomidine 0.5 mcg/kg/hour, which is titrated to achieve target RASS of -1 to 0. They implement delirium prevention measures: minimizing benzodiazepines, promoting sleep with nighttime light reduction and clustered care, mobilizing the patient to sit at the edge of bed, providing reorientation and hearing aids. Haloperidol 1 mg IV is given for episodes of severe agitation. By day 8, delirium resolves, and he successfully completes a spontaneous breathing trial. He is extubated and transferred to the floor on day 10.

### Key Learning Points
- The RASS scale ranges from +4 (combative) to -5 (unarousable), with targets typically -2 to 0 for light sedation that allows assessment and participation
- Benzodiazepines (particularly midazolam) accumulate in critically ill patients and are associated with higher delirium incidence compared to propofol or dexmedetomidine
- The CAM-ICU detects delirium by assessing: acute onset/fluctuating course, inattention, altered level of consciousness, and disorganized thinking
- The ABCDEF bundle integrates Assess/manage pain, Both SAT and SBT, Choice of sedation, Delirium monitoring, Early mobility, and Family engagement

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## Case 3: Early Mobility in ICU-Acquired Weakness Prevention

### Clinical Image
![Physical therapy session with ICU patient demonstrating early mobilization](case_03_image.jpg)
*Source: [Wikimedia Commons - Physical Therapy](https://commons.wikimedia.org/wiki/Category:Physical_therapy) - CC BY-SA 3.0*

### Case Presentation
A 58-year-old man is admitted to the surgical ICU with septic shock from a perforated appendix requiring emergent laparotomy. He requires mechanical ventilation for 12 days, norepinephrine for 7 days, and receives high-dose corticosteroids for vasopressor-refractory shock. By day 14, he is hemodynamically stable off vasopressors and sedation has been weaned. However, when asked to lift his arms, he demonstrates profound symmetric weakness, barely able to overcome gravity (MRC grade 2/5 in proximal muscles). He cannot participate in spontaneous breathing trials due to rapid shallow breathing. The neurology consult diagnoses ICU-acquired weakness (likely combined critical illness polyneuropathy and myopathy) based on clinical examination and EMG findings. An aggressive early mobility program is initiated: day 1 begins with passive range of motion, day 3 progresses to active-assisted exercises in bed, day 5 achieves sitting at edge of bed with two-person assist, and day 8 accomplishes transfer to chair. Physical and occupational therapy visit twice daily. Adequate protein nutrition at 1.5 g/kg/day supports muscle recovery. Corticosteroids are weaned as clinically appropriate. After 3 weeks of intensive rehabilitation, his MRC sum score improves from 32/60 to 48/60, he successfully weans from the ventilator, and he transfers to acute rehabilitation. At 3-month follow-up, he has returned to independent function.

### Key Learning Points
- ICU-acquired weakness affects 25-50% of patients with prolonged ICU stays and is caused by critical illness polyneuropathy (CIP), critical illness myopathy (CIM), or both
- Risk factors include sepsis, prolonged immobility, corticosteroids, neuromuscular blocking agents, and hyperglycemia
- The MRC sum score tests strength in 6 muscle groups bilaterally (total 60 points); scores less than 48 define ICU-acquired weakness
- Early mobilization is the most effective prevention and treatment, with benefits including reduced delirium, shorter ventilator days, improved functional outcomes, and shorter ICU/hospital stay