Published by the Students of Johns Hopkins since 1896
June 22, 2024

Type of spine surgery affects blood loss

By ELLE PFEFFER | April 27, 2012

Hopkins researchers have recently published a study confirming their hypothesis that levels of blood loss vary in children undergoing corrective spine surgery based on the type of underlying spine deformity condition. The results of this study are helpful to pediatric surgeons and open up more opportunities for spine surgery research.
Years ago, Paul Sponseller, chief of pediatric orthopedics at Hopkins Children's Center and Dolores Njoku, a pediatric anesthesiologist, created a spine database. Despite a small sample of patients, they were able to deduce a connection between patient diagnosis and blood loss during surgery.
The new study, published online in Spine, is part of an expansion of these older findings into a new database. Through analysis by Amit Jain, a medical student, the researchers found the same underlying link as with the prior database. The study is unique for its "multidisciplinary approach utilizing expertise in surgery and anesthesiology," Dr. Njoku wrote in an email to The News-Letter.
The study included data from 617 corrective spine surgeries of 37 different diagnoses performed on children between 2001 and 2011 at Hopkins. In order to sort the data, diagnosis types were classified into five groups: idiopathic scoliosis (the most common scoliosis without a known cause), Scheuermann's kyphosis (an elevated roundback in upper spine), cerebral palsy (a set of brain and nervous system disorders), additional neuromuscular disorders (including dystrophies, atrophies or trauma injuries), and genetic or syndromic disorders.
There were a number of variable elements to the procedures that required normalization during analysis. To calculate the normalized blood loss (NBL), Sponseller and Njoku divided the amount of blood lost by the number of spine levels fused during surgery and the patient's weight.
These calculations indicated that patients with cerebral palsy suffered an average blood loss of 3.2 millimeters per kilogram body weight, the highest amount among all of the diagnosis groups. The amount for patients with neuromuscular conditions and genetic syndromes stood at the middle while children with Scheuermann's disease or idiopathic scoliosis ranked at the lowest loss overall.
According to the researchers, the heightened risk for those with neuromuscular or genetic conditions is related to the patients' changed blood-clotting capabilities and their low platelet count, among other reasons.
Children with idiopathic scoliosis face the lowest risk of blood loss during surgery. "They are the healthiest, best nourished (best chance of optimal clotting mechanics)" Sponseller wrote in an email to The News-Letter. "However, interestingly, the standard preop lab measurements of clotting function are normal in all of the conditions studied.
The reason behind the greatest loss in patients with cerebral palsy is still a mystery, but invites further research.
Blood loss during surgery is best avoided for a number of reasons. "The negative effects of blood loss are increased stress on the heart, changes in blood chemistry and drug levels, and exposure to infectious risk from infusions," Dr. Sponseller said.
This study is targeted at helping surgeons and anesthesiologists better anticipate any surgical complications that could lead to longer hospital stays or poor recovery.
"The biggest benefit is that the anesthesiologists and surgeons that care for these patients can be more prepared," Njoku wrote. "The Anesthesiologist gives blood and fluids to the patient in addition to anesthesia to keep the patient asleep. The surgeons may then develop innovative instruments or techniques that may decrease blood loss."
Sponseller adds that blood loss may be reduced by anti-fibrinolytics, inhibitors to fibrin breakdown in blood clots, and an earlier provision of clotting factors.
This study is an entry into discovering what benefits may be reaped from understanding the link between blood loss and diagnosis in spine surgery. "It documents the problem to serve as an impetus for research into the reasons why the difference exists," Sponseller wrote.
"We hope to ignite a spark of interest, which stimulates others with knowledge of coagulation to find the reason . . . For a fairly uniform surgery, hemostatic function differs by disease in ways which would not have been predicted. This is a topic for further study and an opportunity for improvement."

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