He suggests that the male cranium is filled with numerous little boxes, one for the family, one for the car, one for the job, and so on. Importantly, none of these containers touch; quite a clever analogy for how men (in general) think. Recently, a pal was hospitalized with acute compartment syndrome, and little boxes seems like a good place to start.
An airframe is wrapped in skin and has a powerplant, fuel lines providing nourishment, lots of wiring, and rigid bulkheads dividing sections from one another. The human equivalents are the skeleton, skin, muscle, arteries, veins, and nerves, plus a thick, white, fibrous tissue called fascia, and other connective tissues. Pressure plays a role in many areas of aviation; tire pressure, cabin pressure, and manifold pressure. Failing to measure, monitor, and mitigate pressure issues can have serious consequences. Pressure also plays critical roles in humans; obviously blood pressure, but there is also a pressure system inside the head (more of that another day) and pressure inside our limbs. For instance, in the lower leg, the main shin bone—tibia—and adjacent fibula are surrounded by muscle that is nourished by arterial blood, which then drains back to the heart via veins. The entire apparatus is divided into four compartments by fascia.
In the event of lower limb trauma such as a fractured tibia (which men suffer with more frequency than the smarter version of Homo sapiens) the limb swells from internal bleeding and tissue damage. As the compartments are bounded by bone and unforgiving fascia, there is only so much swelling that can occur before rising pressure prevents blood reaching, and nourishing, the muscle. The resulting acute compartment syndrome (ACS) is a medical emergency; depriving muscle, nerves, and other structures of blood can lead to tissue death. While not madly common (approximately 44 cases/day in America), at the most benign ACS can lead to Volkmann ischemic contracture, a fancy name for a “clawed” foot together with chronic pain, sensory loss, and weakness. More severe cases can lead to limb loss, kidney failure, sepsis, and death.
ACS can also be provoked by crush injuries, bleeding from taking anticoagulants for heart problems, a tight cast or dressing, complicated cardiac treatment with ECMO(extracorporeal membrane oxygenation), long operations, bad bruising without fracture, burns, or even sleeping in an odd position perhaps after over-indulging in alcohol. Skiing accidents and cycling or motorcycle and motor vehicle crashes are common causes, and even seemingly minor injuries can precipitate ACS. This can happen in the forearm, foot—anywhere that has bones, muscles, fascia, and all the other paraphernalia.
If one detects an evolving ACS, the treatment is a fasciotomy, where the leg is opened widely and the fascia incised, allowing space for swelling. While it is an effective operation, it can lead to extensive wounds, lengthy recovery, and other postoperative challenges. Ideally, it should only be deployed when there is no doubt that there is a case of ACS brewing. And that is where the whole thing gets tricky, and where Mr. Woods enters the story. In 2021 the golfer had a motor vehicle accident, suffering a nasty leg injury and ACS, and reportedly underwent a fasciotomy. Missing a case of ACS can, as above, lead to disability, even death and invariably expensive lawsuits. Doing an unnecessary fasciotomy is no pleasure flight, though. So how is the diagnosis made?
When I had a lower limb fracture many moons ago, I recall the young doctor pestering me hourly asking how my pain was; I fantasized about doing him harm…it hurt! And he kept asking me if it was better, the same, or worse. You see, the textbooks describe how to diagnose ACS with a memory trick, the “6 P’s”:
Pain – out of proportion to the apparent injury; I always thought this to be a dopey idea, but the books also say it is pain that gets worse despite the injury being immobilized and meds being administered. They also talk about pain on stretching the muscles—this was the point where I was contemplating how badly I was going to hurt the doctor who was asking me. Other findings suggestive of ACS are:
Paresthesias (tingling or numbness) – due to nerve damage.
Pallor – pale skin in the affected limb because blood is not reaching the area.
Paralysis – because of muscle damage there is a lack of movement.
Pulseless – the pulse can normally be felt in the ankle and foot and its disappearance is ominous.
Poikilothermia – a fabulous medical word, the limb feels “perishingly cold” again due to no blood.
Porkiness – tightness or fullness in the limb; it appears tense and woody with shiny skin.
However, once established, these signs imply significant damage has already occurred and data has demonstrated that these signs are not much use; as pilots, check lists are gold dust and measurement is a founding principle. So it is in modern medicine; enter intracompartmental pressure measurement, whereby a needle probe can be inserted into one or more of the compartments. While this was initially done to take spot measurements, it soon became clear that the trend was more valuable and the concept of continuous pressure monitoring was born. This is of special value in patients who are incapable of communicating their symptoms due to multiple injuries, intoxication, or sedation. Further, the medical team may ascertain the changing compartment pressure and the diastolicblood pressure, the bottom number in a blood pressure reading that measures the force of your blood against your artery walls when your heart is at rest between beats. If the muscle compartment pressure is higher than diastolic, it will be “harder” for blood to get into the limb, making ACS more likely. If the pressure trend is down, no action is taken if clinical signs remain stable, as the doctor’s observations are key.
If caught early with fasciotomy, outcomes are generally good, but the longer one waits, the greater the risk of permanent damage to muscles and nerves.
This mechanism also leads to a more benign condition in runners: chronic exertional compartment syndrome(CECS). With exercise, muscle expands and the compartment cannot accommodate the increased demand for blood. The resultant incapacitating pain forces one to rest and elevate the painful leg whereupon symptoms abate. This may be conflated with “shin splints” (medial tibial stress syndrome) a nasty pain emanating from membrane overlying the bone. Unlike ACS, CECS is not an emergency and can be diagnosed with pressure testing before and after exercise, and if the pain and infirmity are restrictive, an elective fasciotomy can be performed.
In medicine, as in aviation, pressure is only safe when it stays within limits. Once it climbs unchecked, immediately seek expert maintenance.
Fly well!
Disclosure: Dr. Sackier hosts a podcast entitled “Under Pressure” supported by MY01, a Canadian medical device company in which he also owns stock.
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