Post-operative delirium may indicate increased vulnerability of patients’ brains.

Post-operative delirium may indicate increased vulnerability of patients' brains.

Understanding the Impact of Postoperative Delirium on Older Patients

Delirium is a common occurrence among older patients who undergo surgery, causing significant complications and distress. For years, the cause of postoperative delirium has remained a mystery. However, recent research has shed light on the issue by discovering that patients who develop postoperative delirium have increased openings in the blood-brain barrier, a layer of cells that typically prevents substances from entering the brain1.

Dr. Michael Devinney, the study author and assistant professor of anesthesiology at Duke University School of Medicine, stated that these findings provide a roadmap for tackling a problem that affects millions of older adults in the U.S. annually. By preventing the blood-brain barrier from opening after surgery or identifying substances bypassing the barrier and reaching the brain, researchers can potentially develop therapies to prevent postoperative delirium2.

Postoperative delirium affects up to 40% of older patients who undergo surgery. It manifests as a type of confusion that occurs within the first few days after the procedure. This condition is associated with longer hospital stays, significant distress, and major post-operative complications. Studies conducted on mice have also indicated that disruptions in the blood-brain barrier are likely the cause for this condition3.

Additionally, the study found that patients who showed lower performance on memory and thinking tests before surgery were more likely to experience postoperative delirium. To investigate this further, scientists studied over 200 patients aged 60 and above before and after their non-cardiac and non-neurological surgeries. Spinal fluid and blood samples were collected from the participants both before the surgery and 24 hours after. The researchers measured the ratio of albumin, a protein that signifies the barrier’s fluidity, as an indicator of the blood-brain barrier’s permeability4.

Extensive cognitive evaluations were also conducted on the study participants before and after surgery. The results revealed that increased permeability in the blood-brain barrier was associated with higher rates of delirium and longer hospital stays for all patients. This suggests that the increase in permeability is the body’s response to the surgical procedure. Furthermore, the study found that poorer performance on cognitive tests before surgery independently contributed to the risk of postoperative delirium5.

The researchers hypothesize that postoperative delirium may follow a two-hit model. This model involves a predisposing factor such as impaired preoperative cognition, as well as a precipitating factor related to blood-brain barrier dysfunction after surgery. It is known that inflammatory molecules can pass through a leaky blood-brain barrier and cause cognitive impairments. As a follow-up to this study, the researchers plan to analyze the collected spinal fluid samples to determine whether patients who experienced delirium have higher levels of specific inflammatory factors6.

The study, funded by the U.S. National Institutes of Health, was recently published in the Annals of Neurology7. The findings provide valuable insights into the factors contributing to postoperative delirium and offer new possibilities for prevention and treatment.

Conclusion

Postoperative delirium poses a significant challenge for older adults undergoing surgery and can lead to serious complications and distress. However, recent research has uncovered a potential explanation for its occurrence. Patients who develop postoperative delirium have increased openings in the blood-brain barrier, allowing substances to enter the brain. By understanding this mechanism better, researchers can work towards developing therapies to prevent postoperative delirium in the future.

The study also found that patients with lower preoperative cognitive performance were more susceptible to postoperative delirium. The findings highlight the importance of assessing cognitive function prior to surgery and addressing any potential risk factors. By identifying impairments beforehand, medical professionals can take proactive measures to minimize the risk of delirium.

Future research will explore the connection between postoperative delirium and inflammatory factors in the spinal fluid. Leaky blood-brain barriers permit the passage of inflammatory molecules into the brain, which can result in cognitive impairments. By studying these factors, researchers aim to gain a more comprehensive understanding of the condition and develop targeted therapies.

Postoperative delirium affects a significant portion of older patients undergoing surgery, and its impact cannot be underestimated. The latest study provides crucial insights into its causes, paving the way for improved care and intervention strategies. By actively addressing the blood-brain barrier’s permeability and early cognitive assessment, medical professionals can mitigate the risk of postoperative delirium and ensure better outcomes for their patients.

References


  1. Delirium After Surgery May Be Due to Increased Openings in Blood-Brain Barrier↩︎

  2. Delirium After Surgery May Be Due to Increased Openings in Blood-Brain Barrier↩︎

  3. Delirium After Surgery May Be Due to Increased Openings in Blood-Brain Barrier↩︎

  4. Delirium After Surgery May Be Due to Increased Openings in Blood-Brain Barrier↩︎

  5. Delirium After Surgery May Be Due to Increased Openings in Blood-Brain Barrier↩︎

  6. Delirium After Surgery May Be Due to Increased Openings in Blood-Brain Barrier↩︎

  7. Delirium After Surgery May Be Due to Increased Openings in Blood-Brain Barrier↩︎