Altered Mental Status in a Patient With Sepsis

Case Study

A bedside nurse initiated a rapid response event for a patient with new-onset altered mental status. On prompt arrival of the rapid response team, it was noted that the patient was a 72-year-old female with a history of coronary artery disease, hypertension, chronic kidney disease stage three, hypothyroidism, chronic obstructive pulmonary disease (COPD), tobacco dependence, and prior stroke with residual left-sided weakness. She was admitted a day ago with concern for COPD exacerbation. The nurse reported that the patient was alert and oriented to person, place, time, and situation when she arrived from the emergency department (ED), and prior to hospitalization, she lived at home and has no known history of dementia. She was noted to have had a decreased appetite earlier in the morning during breakfast. Chart review showed that she had received a chest X-ray (CXR) in the ED, which did not show any acute infiltrate. Nursing staff reported her oxygen requirement increased to 4 L/min (LPM) of oxygen instead of 2 LPM that she was on since admission, and she had been more confused and was picking at her intravenous (IV) line when afternoon vital signs were being obtained.

Vital Signs

Temperature: 101 °F, axillary
Blood Pressure: 89/50 mmHg
Heart Rate: 102 beats per min, sinus tachycardia on telemetry
Respiratory Rate: 22 breaths per min
Pulse Oximetry: 94% on 4 LPM O ₂via nasal cannula

Focused Physical Examination

A quick exam revealed a lady appearing slightly older than the recorded age. She was trying to remove her IV line during this exam. On orientation questions, she believed she was at home and that she had to get up to get ready for work. She would not follow commands appropriately and could not give thumbs up on either hand. There was no evidence of facial droop, and her pupils appeared equal in size bilaterally. She was moving both arms spontaneously. Her cardiac, pulmonary, and abdominal exams were unremarkable.

Interventions

A bedside glucose level was checked, which was 80 mg/dL. A 1 L bolus of lactated ringers was given. Labs including complete blood count (CBC), basic metabolic panel (BMP), thyroid-stimulating hormone (TSH), lactate, arterial blood gas (ABG), and blood cultures were sent. Her blood pressure came up to 95/55 after 500 cc of IV fluids were infused, and she was ordered another 1.5 L of IV fluids to achieve a total of 30 cc/kg of IV fluids. ABG showed a pH of 7.36, PaCO ₂ of 50, and PaO ₂ of 74 with an of O ₂ saturation of 94% when the sample was drawn. There was no evidence of hypercarbia or significant discrepancy between the PaO ₂ and SpO ₂ . A TSH was sent because of her history of hypothyroidism; however, the fever, hypotension, and recent cold symptoms made infection higher on the differential. She was started on ceftriaxone IV and continued on azithromycin. She did have a history of stroke, and during episodes of hypotension, recrudescence of old deficits can occur. During the rapid response event, her mental status improved after her IV fluids were administered, likely because of correction of hypotension and improved cerebral perfusion.

Final Diagnosis

Septic encephalopathy.

Septic Encephalopathy

Changes in mental status often occur early in sepsis and often before other organ system dysfunction begins. Septic encephalopathy is thought to result from oxidative stress, increased cytokine and pro-inflammatory factor levels, disturbances in cerebral circulation, changes in the blood-brain barrier permeability, and injury to the brain’s vascular endothelium. It is important to note that 45% of patients who recover from sepsis will show cognitive dysfunction one year after hospitalization.

Septic encephalopathy can be differentiated from an acute stroke as there is typically a global change in mental status, and examination is typically not consistent with focal weakness. In order to treat the encephalopathy, sepsis itself must be treated (see Table 37.1 for potential causes of sepsis). Sepsis treatment includes circulatory support with IV fluids, typically 30 cc/kg as a bolus, and vasopressor support if needed, as this will help ensure adequate cerebral perfusion. Broad-spectrum antibiotics should be initiated as soon as possible, ideally in less than 60 min. The choice of antibiotics depends on the patient’s underlying risk factors, including immunosuppressive status, recent antibiotics use, and prior history of infection with a specific bacteria. If there is a concern for meningitis, then those antibiotics should be chosen that have known penetration through the blood-brain barrier. Renal function should be considered in antibiotic dosing decisions, as kidneys are a common casualty in sepsis and shock. However, this information may not be available at the time, and the regimen can be tailored as lab results become available.

Table 37.1

Potential causes of septic encephalopathy

Skin/soft tissue infection	CSF-meningitis, encephalitis, abscess	Intra-abdominal abscess	Pneumonia
Bacteremia, candidemia	Discitis	Ascending cholangitis	Pleural effusion
Endocarditis	Dental or sinus abscess	Acalculous cholecystitis	Empyema
Osteomyelitis	Deep neck space infection	Spontaneous bacterial peritonitis	Urinary and genitourinary tract infections, toxic shock syndrome