Jacksonville Post-Operative Visual Loss Lawyers
Avoiding Vision Loss from Spinal Surgery
Vision loss from spinal surgery is more common than you would think. The medical condition is called post-operative visual loss, or POVL, and it occurs when an anesthesiologist fails to maintain the proper blood pressure during a spine surgery of six hours or more. The visual loss can include blindness and is totally preventable.
What Causes POVL?
During surgery on the lumbar spine, the anesthesiologist and surgeon must maintain adequate blood circulation and oxygenation. When there is a decrease in the blood that carries oxygen to the optic nerve, blindness can result. The condition is called ischemic optic neuropathy, but rarely is it discussed with the patient before surgery.
Several conditions during surgery can result in vision loss.
Duration of Surgery and Blood Loss
POVL can occur when a spinal surgery lasts six hours or more and where there is a loss of at least one liter of blood.
During surgery, blood carries oxygen to body tissues using hemoglobin in the red blood cells. The percentage of red blood cells in the blood is called the hematocrit. The normal hematocrit level is 50 percent. If a patient loses a large amount of blood during surgery, replacement fluids are given. These fluids also serve to dilute the blood, lowering the hematocrit level and reducing the blood’s ability to carry oxygen to the tissues.
If during surgery, the arterial blood pressure is reduced by the surgeon to curtail bleeding, oxygen to the tissues is further reduced.
Since spinal surgery is performed when the patient is lying on his stomach, there is an increase in abdominal pressure on the large vein that returns blood to the heart. If the patient is overweight or obese, additional pressure from the weight means there will be an even greater reduction in the amount of blood returning to the heart during the surgery.
What’s curious is that the brain does not suffer injury from prolonged low oxygenation. The brain has a mechanism by which it maintains adequate oxygenation by increasing cerebral blood flow. The optic nerve does not do this, according to one study done on pigs and published in the journal Anesthesiology.
Because these conditions are present in spinal surgeries, the risk of POVL is reported to be 22 to 23 times greater when compared to other surgeries. For the longer spine surgeries of six hours where there is blood loss of a liter or more, the risk of POVL is about 135 to 175 times greater than for a shorter spine surgery with less blood loss.
If a surgery lasts greater than six hours, and involves at least a liter of lost blood, the risk rises to a shocking 2,655 to 3,319 times greater than other surgeries.
Anyone with vascular disease, hypertension, diabetes, and a large belly is not a good candidate for the type of spinal surgery that can last six hours or more.