From the Guidelines
Fever after anesthesia is most commonly caused by non-infectious factors, such as the surgical stress response or medications, within the first 48 hours, while fever after 48 hours is more concerning for infection, such as surgical site infections or urinary tract infections 1.
Common Causes of Post-Anesthesia Fever
- Surgical site infections
- Urinary tract infections
- Atelectasis
- Medication reactions
- Malignant hyperthermia
- Transfusion reactions
Evaluation and Management
The initial approach should include a thorough assessment of vital signs, physical examination, and basic laboratory tests including complete blood count, urinalysis, blood cultures, and chest X-ray 1.
- If infection is suspected, empiric antibiotics should be started after cultures are obtained, with the regimen tailored to the suspected source.
- Malignant hyperthermia, though rare, requires immediate treatment with dantrolene 2.5mg/kg IV, discontinuation of triggering agents, cooling measures, and supportive care.
- Prevention strategies include proper surgical technique, appropriate antibiotic prophylaxis, early mobilization, incentive spirometry, and adequate pain control.
Timing of Fever
- Fever within the first 24 hours is often due to the surgical stress response or medications.
- Fever after 48 hours is more concerning for infection, such as surgical site infections or urinary tract infections 1.
Specific Considerations
- The anesthesia record should be reviewed for medications administered and any complications during the procedure.
- A chest radiograph is not mandatory for evaluation of postoperative fever unless respiratory rate, auscultation, abnormal blood gas, or pulmonary secretions suggest a high probability of utility 1.
- Urinary tract infection is common postoperatively because of the use of urinary drainage catheters, and a urinalysis or culture is not mandatory to evaluate fever during the initial 2 to 3 days postoperatively unless there is reason by history or examination to suspect an infection at this site 1.
From the Research
Causes of Post-Anesthesia Fever
- Postoperative fever can be caused by a normal inflammatory response to surgery, resulting from inflammation caused by surgical trauma and blood contact with cardiopulmonary bypass circuit, leading to the release of cytokines 2, 3
- Fever can also be a manifestation of a serious underlying infectious or noninfectious etiology, but this is less common 3, 4
- The use of general anesthesia seems to inhibit fever by decreasing the thermoregulatory-response thresholds to cold, while opioids also inhibit fever, although to a lesser extent 5
- Epidural anesthesia does not affect fever, suggesting that hyperthermia associated with epidural infusions may be a true fever caused by inflammatory activation 5
Evaluation of Post-Anesthesia Fever
- A systematic and prudent evaluation of fever is necessary to rule out life-threatening conditions, but extensive evaluations with cultures and chest imaging may have little to no benefit in patients admitted for elective surgery 6, 4
- A brief bedside evaluation has the highest yield for determining the fever etiology, and physical exam and clinical picture can accurately diagnose the infection without need for further testing in many cases 4
- The role of advanced practice registered nurses (APRNs) in managing surgical patients requires being able to accurately assess and evaluate the cause of postoperative fever and take action accordingly, taking into account a variety of factors such as patient's medical history, physical examination findings, and type of surgery 3