Have you ever wondered in a boxing match, why the coach is always shouting at the boxers not to blow their nose if they get hit in the face? The following answers should explain the reasons behind it.
Emergency physician here. The most important reason is to prevent infection. Fighters often develop small cracks in the bone that separates their sinuses and their orbit (eye socket). Blowing their nose increases sinus pressure and forces air and often bacteria into the space behind their eyes. This will cause swelling, but can also lead to bacterial infection of the space, and potentially spread of that infection to the brain.
After a fighter’s eye and the face around it have been properly tenderized by a four- to five-ounce boxing glove, the blood vessels – especially the veins – are damaged.
Some of the veins are completely torn and some are just leaky. This vascular injury and direct trauma to the soft tissue causes the puffiness, swelling and the very familiar “mouse” under the eye. The acts of blowing your nose, grunting, straining during exercise (commonly lifting weights), pushing for a bowel movement, etc. increases venous blood pressure. This physiological event is called a Valsalva maneuver.
Unfortunately, increasing the venous blood pressure (by blowing one’s nose) after the soft tissue surrounding the eye has been damaged causes a rapid loss of blood from the leaky veins and profound swelling, which results in a closed eye.
The increase in blood pressure during a fight causes more bleeding too.
This happened to me once. I was sparring the previous day and I got a solid hook in my eye. It hurt, but there was no swelling. The following morning, as I was washing my face, I blew my nose and my eyelids inflated. My eye was shut.I was mortified. I never knew this was possible and I got so scared. I didn’t know how to fix it. This happened due to a fracture in the orbital bone, and air flew into the hole. It took a week for the eye to come back to normal and I was scared of blowing my nose for a while.
The main reason fighters (patients) are instructed to not blow their nose after sustaining trauma to the eye/nose region is to prevent tissue emphysema. Most of the bones in a person’s mid-face (orbits/nose/sinuses) act like shock absobers to protect more valuable tissue like the brain. Hence, the bones of the maxillary sinus, orbital floor are very thin. Some are 0.65mm. Most people who sustain this type of trauma are placed on what’s called “Sinus Precautions” meaning to avoid blowing their nose for 4-6 weeks.
In the case of Eddie Alvarez, you can see some initial swelling around his left eye, meaning he possibly sustained a minor fracture of his sinus or orbital floor. Once he closes his left nostril and blows, the air has nowhere to go but up through that minor fracture and now has tissue emphysema and increase swelling; leading to a decrease in vision.