The July issue of Anesthesiology had 2 really intriguing articles that I’d like to review for the PAAD readership. Unfortunately, both are on topics that I know nothing about. The first by Puglia et al (Puglia MP, Vlisides PE, Kaplan CM, Jewell ES, Therrian M, Mashour GA, Li D. Constrained Functional Connectivity Dynamics in Pediatric Surgical Patients Undergoing General Anesthesia. Anesthesiology. 2022 Jul 1;137(1):28-40. PMID: 35363264), goes to the very heart of what anesthesia does: how do anesthetic agents produce unconsciousness and are children different than adults? I found the article and science to be completely incomprehensible. I’m hoping one of you reading today’s PAAD understands this topic or knows someone who does (or maybe one of the authors) and can summarize it for a future PAAD.
The second article which I will review is on the gut microbiome and its effects in anesthesia and pain management. Admittedly, this also is a topic I really know nothing about but I’ll do my best to summarize its key points. What is the gut microbiome and how and why it may affect anesthesia, critical care and pain management is pretty startling. I can’t possibly do justice to all of the information contained in today’s article and after offering you this taste would urge you to dive in and read it in its entirely. Myron Yaster MD
Original article
Minerbi A, Shen S. Gut Microbiome in Anesthesiology and Pain Medicine. Anesthesiology. 2022 Jul 1;137(1):93-108. PMID: 35486831
“The human microbiome is an intricate ecosystem, typically hosting hundreds to thousands of bacterial species, as well as viruses, fungi, and phages, which is constantly shaped by the host and its environment while also influencing its function, its health, and diseases. While the terms microbiota and microbiome are sometimes used interchangeably, they are not synonymous. Traditionally, microbiota refers to the ecological community of microorganisms hosted by a multicellular organism, while microbiome refers to the genomes of these microorganisms. More recent definitions regard the microbiome as the microbiota within its well-defined habitat, forming its theater of activity, including microbial and external structural elements such as genes, lipids, proteins, polysaccharides, and metabolites.”1
“The complexity of the human microbiome may be conceptualized by considering its size, diversity, and dynamics: the human body hosts hundreds of bacterial species, and the number of these bacterial cells is estimated at 1.3 times the number of human cells. The number of bacterial genes, however, is two to three orders of magnitude larger than that of human genes. This huge bacterial community is highly variable between individuals: while the human genome is 99.5% identical between any two individuals, the composition of their gut microbiomes differs considerably, even between identical twins or individuals who share a common living environment.”1
“The composition of the microbiome is also dynamic: the relative abundance of bacterial taxa in the human host changes over time scales of years, months, and even days in response to a multitude of host- and environment-related factors, including age, diet, occupation, physical activity, and medications.”1
It is this dynamic change that has importance to us as clinicians. There is “accumulating evidence on the interactions of the gut microbiome with the central and peripheral nervous systems (the “gut-brain axis”) holds the potential to offer new mechanistic insights regarding pathologies relevant to anesthesiologists and pain physicians. Specifically, association studies demonstrate gut microbiome alterations that correlate with both chronic pain and some postoperative outcomes in humans. Animal models provide evidence that the gut microbiome may play a role in the pathogenesis of these conditions, proposing possible mechanisms mediating this effect.”1 Both the anesthetic and other drugs we use perioperatively and the inflammatory responses to surgery profoundly affect the gut microbiome. Could these changes play a role in perioperative pathology?
To date most of the findings on how the microbiome produces or affects pathology have been correlations not causation studies, and as Jim Dinardo and our cardiac PAAD contributing writers always like to point out: “corelations do not establish causality”.
Many laboratory studies are underway to establish causality. But just think of the possibilities! Why do some patients respond differently to analgesics? Are differences in the microbiome responsible for chronic pain conditions (why do some patients develop chronic pain after surgery and some do not)? How do the antibiotics we use as part of surgical site infection prophylaxis affect the microbiome? Does preventing one problem produce another?
Manipulation of the gut microbiome to reverse dysbiosis and restore a “healthy” microbiome composition may become an essential part of perioperative care. “This may be achieved by the use of dietary measures, including prebiotics, probiotics, and medications, or by means of fecal microbiome transplantation (“fecal transplants”) from healthy individuals”1 perioperatively.
Wow! I hope I’ve intrigued you enough to read the article in its entirety.
References
1. Minerbi A, Shen S: Gut Microbiome in Anesthesiology and Pain Medicine. Anesthesiology 2022; 137: 93-108