Perioperative outcomes in myalgic encephalomyelitis/chronic fatigue syndrome undergoing general anesthesia: a retrospective matched-pair study

This retrospective matched-pair study indicates that while general anesthesia is hemodynamically well-tolerated in patients with myalgic encephalomyelitis/chronic fatigue syndrome, they experience significantly higher postoperative pain and a greater need for rescue analgesia compared to matched controls.

The Gist

Imagine your body is like a high-performance car. For most people, this car runs smoothly, but for those with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), the engine is incredibly sensitive. A tiny bump in the road (like a little bit of exercise or stress) can cause the whole car to sputter, stall, or break down for days. This condition is mysterious, and doctors often don't have a clear "owner's manual" for how to handle it during surgery.

This study was like a team of mechanics trying to figure out what happens when they put this sensitive car on a lift and run a diagnostic test (general anesthesia).

The Experiment: A Side-by-Side Comparison

The researchers looked back at medical records from a big hospital to find 15 patients with ME/CFS who had surgery. To make a fair comparison, they paired each of these patients with a "twin" patient who was similar in age, health, and surgery type but did not have ME/CFS. Think of it as comparing two identical cars, where one has a super-sensitive engine and the other is a standard model.

What They Found: The Engine vs. The Dashboard

1. The Engine (Blood Pressure and Heart Rate)
The team was worried that the "sensitive engine" might struggle under the stress of anesthesia. They watched the blood pressure and heart rate like a mechanic watching the tachometer.

• The Result: The sensitive car did run a little "cooler" and slower than the standard car. The ME/CFS patients had slightly lower blood pressure and heart rates during the surgery.
• The Good News: Even though the numbers were lower, the engine didn't stall! No one had a dangerous drop in pressure, and the doctors didn't need to use extra tools (like emergency fluids or blood-pressure-boosting drugs) to keep the car running.
• Analogy: It's like driving a hybrid car that idles very quietly. It's different from a gas-guzzler, but it's still running perfectly fine.

2. The Dashboard (Pain and Recovery)
This is where the story got interesting. While the engine was fine, the "dashboard" (how the patient felt) told a different story.

• The Result: After surgery, the ME/CFS patients were in significantly more pain than the control group. They needed painkillers (opioids) much more often.
• Analogy: Imagine two people getting a small scratch on their arm. The standard patient feels a little pinch and moves on. The ME/CFS patient feels like they've been hit by a truck. Their "pain sensors" are turned up to maximum volume, making the recovery much more uncomfortable.

3. The Other Stuff (Nausea, Staying in the Hospital)
Interestingly, the ME/CFS patients didn't get sicker in other ways. They weren't more nauseous, didn't need extra oxygen, and didn't stay in the recovery room longer than the others.

The Missing Piece: The "After-Effect"

The study had one big blind spot. ME/CFS is famous for Post-Exertional Malaise (PEM)—a phenomenon where doing something small (like surgery) causes a massive crash days or weeks later.

• The Limitation: This study only looked at the immediate recovery (the first few hours). It's like testing a car right after a race but not checking if the engine blows up three days later. The researchers admitted they couldn't see if the surgery caused a delayed "crash" for these patients.

The Bottom Line

• Good News: Putting ME/CFS patients to sleep for surgery seems safe. Their hearts and blood pressure handle the anesthesia well.
• Caution: These patients feel much more pain after waking up. Doctors need to be extra prepared with pain management plans, almost like giving a "pain shield" to these patients.
• Future Work: We still need to do more research to see what happens in the days after the surgery, because that's where the real mystery of ME/CFS lies.

In short: The surgery itself is safe for the "sensitive engine," but the "pain dashboard" needs a lot more attention.

Technical Summary

Technical Summary: Perioperative Outcomes in ME/CFS Undergoing General Anesthesia

1. Problem Statement

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex, multisystem disorder characterized by profound fatigue, post-exertional malaise (PEM), cognitive impairment, and autonomic dysfunction. While the pathophysiology involves immune, autonomic, and metabolic dysregulation, there is a significant lack of evidence-based guidelines for anesthetic management in these patients. Clinicians face uncertainty regarding how ME/CFS patients tolerate general anesthesia, particularly concerning hemodynamic stability and postoperative pain management. This study addresses the gap in clinical data by investigating perioperative responses in ME/CFS patients compared to matched controls.

2. Methodology

• Study Design: Retrospective matched-pair analysis conducted at a single tertiary center.
• Study Period: 2015 to 2026.
• Population:
  • Cases: Patients diagnosed with ME/CFS (identified via ICD-10 codes G93.3 and U09.9) undergoing general anesthesia.
  • Controls: Matched 1:1 to cases based on relevant criteria.
• Inclusion/Exclusion Criteria:
  • Included patients with confirmed ME/CFS diagnoses.
  • Excluded patients with confounding diagnoses or an American Society of Anesthesiologists (ASA) physical status classification above III.
  • Manual verification was performed on all identified cases to ensure diagnostic accuracy.
• Data Collection:
  • Intraoperative: Baseline, post-induction, median, and lowest recorded systolic blood pressure (SBP) and heart rate (HR).
  • Interventions: Vasopressor use and fluid administration volumes.
  • Postoperative (PACU): Maximum pain scores (Numeric Rating Scale, NRS), requirement for rescue analgesia (opioids), nausea/vomiting, oxygen supplementation, and length of stay.
• Sample Size: From an initial pool of 189 identified individuals, 15 matched pairs (30 total patients) were included after applying exclusion criteria.

3. Key Contributions

• First Retrospective Matched-Pair Analysis: This study provides the first comparative clinical data specifically focusing on the perioperative course of ME/CFS patients under general anesthesia.
• Hypothesis Generation: It establishes a baseline for hemodynamic and analgesic responses, identifying specific areas (pain management) that require targeted clinical attention.
• Identification of Research Gaps: The study explicitly highlights the absence of data regarding Post-Exertional Malaise (PEM) in the perioperative setting, defining it as a critical target for future prospective research.

4. Results

• Hemodynamic Stability:
  • ME/CFS patients demonstrated significantly lower intraoperative hemodynamic nadirs compared to controls.
  • Lowest SBP: 90 mmHg (IQR 82.5–95.0) in ME/CFS vs. 100 mmHg (IQR 90.0–110.0) in controls ($p = 0.044$).
  • Lowest HR: 50 bpm (IQR 40.0–57.5) in ME/CFS vs. 60 bpm (IQR 50.0–65.0) in controls ($p = 0.012$).
  • Interventions: Despite lower nadirs, there was no significant difference in vasopressor use or fluid administration. Crucially, no episodes of severe hypotension or perioperative adverse events occurred in either group.
• Postoperative Pain and Analgesia:
  • ME/CFS patients experienced significantly higher pain burdens.
  • Maximum Pain Score: 5.0 (IQR 4.0–6.0) in ME/CFS vs. 1.0 (IQR 0.0–4.0) in controls ($p = 0.008$).
  • Rescue Analgesia: 80% of ME/CFS patients required opioid rescue analgesia compared to 33% of controls ($p = 0.039$).
• Other Outcomes: No significant differences were observed between groups regarding postoperative nausea/vomiting, oxygen supplementation requirements, or PACU length of stay.

5. Significance and Implications

• Clinical Safety: The findings suggest that general anesthesia is generally hemodynamically well-tolerated in ME/CFS patients, even though they exhibit lower baseline intraoperative blood pressure and heart rate.
• Management Strategy: The study indicates a need for tailored analgesic strategies for ME/CFS patients, as they are prone to higher postoperative pain scores and increased opioid requirements.
• Future Research Direction: The study underscores the necessity for prospective investigations to evaluate long-term outcomes, specifically the impact of surgery on Post-Exertional Malaise (PEM), which was not captured in this retrospective design. These findings serve as a foundation for optimizing perioperative protocols to improve patient-centered outcomes in this underserved population.