Last time, we discussed the rib cage, an important shield against trauma to the vital organs in the chest. Though they’re protective, the ribs can fracture if enough kinetic force is applied against them. Rib fractures are most dangerous if a bone fragment is forced inward and punctures the lung or the heart. In the case of the heart, a puncture off the grid is pretty much fatal.
Pneumothorax
With a puncture to the lung, air enters the chest (also called the “pleural”) cavity, causing a condition known as a “pneumothorax.” What happens in a pneumothorax due to blunt trauma? As the patient breathes, air enters the lung and exits through the puncture. This is called a “tension pneumothorax,” because, as more and more fills the cavity, it has nowhere to go and causes pressure or “tension” against the lung that makes it more difficult to fill with air. The lung eventually collapses under the increased pressure.
If blood is filling the chest cavity it’s called a “hemothorax.” You can tell the difference between a tension pneumothorax and a hemothorax. Hemothorax is characterized by a dull sound on tapping against affected side.( This technique is called percussion and is part of the routine exam of the chest and abdomen). The entire exam is explained in the Survival Medicine Handbook (SMH) Normally, air in the chest cavity sounds resonant, like a drum. In a tension pneumothorax, it will be more resonant than normal. If it’s dull where it shouldn’t be, it could be a hemothorax. If the sound made by percussion is dull at the bottom and extra loud at the top of the lung, it’s likely a combination of the two. That’s called a “hemopneumothorax.”
Although a person with a very small pneumothorax will complain of pain with breathing or some shortness of breath, the condition may sometimes resolve on its own or with, if it’s available, portable oxygen. It may progress, however, to a “tension pneumothorax.” Usually caused by significant trauma, the victim may have increasing signs of bluish skin coloration called “cyanosis.” This means there isn’t enough oxygen getting to the victim. Other telltale signs include distended neck veins, worsening rapid breathing, and elevated heart rate. The victim may go into shock. If you use a stethoscope as explained in our SMH, you will hear crackling sounds or, sometimes, no breath sounds at all on the affected side.
Needle Decompression
With a tension pneumothorax from a rib fracture, a procedure called emergency needle decompression is indicated if there isn’t an open wound that allows air to escape. Decompression should only be attempted off the grid if it’s clear the patient will die without action taken on their behalf. It’s a temporary measure to relieve high pressures that are causing the victim to go into shock.
To perform needle decompression:
1) Wearing gloves, clean the area of the chest on the affected side with an antiseptic solution like Povidone-iodine solution (betadine) or Chlorhexidine (Hibiclens). Both are useful additions to the survival medicine cabinet. Your target is the intercostal space (the space between the ribs) just above the third rib and about midway between the center of the collarbone and the nipple. An alternative would be the space between the 4th and 5th ribs in a line straight down from the front of the armpit (called the “anterior axillary line”). A simple medical device known as “Thorasite” can be used as an anatomical landmark guide to help correctly identify the appropriate location for the procedure.
2) Using a 10-14-gauge 3.25-inch decompression needle with a catheter “sleeve” available online, enter the skin just above the rib at a 90-degree angle to the chest wall. This will avoid blood vessels and nerves, which travel just below the rib. Be sure to stay to the outside of the nipple line and, if on the left side, not pointed towards the heart.
3) Enter with the needle while listening for a pop and a hiss. This indicates air passing through as you go through the edge of the chest cavity. Accumulated air should exit through the needle and allow the lung to inflate.
4) Remove the metal needle and secure the remaining plastic sleeve (the “catheter”) in place with tape.
If you are using the alternative axillary approach, beware of going too low, as the liver rises just under the rib cage on the right side and the heart is present on the left side. With the frontal approach, avoid going too close to the breastbone (sternum) or, on the left side, the heart.
Many are taught to place a valve of some sort over the catheter once placed. This is meant to prevent air from returning to the lung cavity. Some needles may have a stopcock for this purpose. Otherwise, an item known as a “vented chest seal” may be used as a covering.
Chest Seals
Vented chest seal
A useful item for medical storage would be a “chest seal.” Various varieties are available online or at our store. Asherman, Hyfin, and other vented chest seals help secure the catheter in place. Make sure that the seal does not prevent air from escaping through the needle.
When penetrating trauma like a stab or gunshot collapses a lung, it’s termed an “open pneumothorax” or a “sucking chest wound.” In these cases, needle decompression is unnecessary as there is already an opening (the wound) that allows air to escape and prevent tension. The air that enters through the wound while healing, however, accumulates, collapsing the lung, and must be treated.
In order for a lung to re-inflate, a chest seal must be placed over the site of entrance wounds (and exit, if any). You goal is to provide a way for the air to escape from the chest cavity wound, but not to go back in.
To apply a chest seal:
1) Position the victim so that breathing is easiest.
2) Wipe all edges of the wound clean with antiseptic and dry with clean/sterile gauze.
3) Wait for the patient to exhale and apply the seal without touching the inside adhesive surface.
4) Repeat this process for exit wounds as well.
The desired effect of a properly placed chest seal is to decrease the pressure in the lung cavity that is preventing the lung from inflating. Your patient should start to breathe easier as air exits through the vent.
Improvising a Chest Seal
Improvised chest seal
Although many commercial vented seals are available, one can be improvised by taking a 4-6-inch square of plastic wrap or other airtight material and firmly taping three sides on top of the wound. The open fourth side will serve as a valve and allow air to escape and the lung to inflate, while not letting air back in. The open side should be facing down to gravity to allow drainage. Do not seal all four sides. If this fails, sometimes the wound opening could be spread slightly with an instrument to allow air to exit and the seal replaced.
A successful needle decompression or chest seal placement is only the start in a wound that collapses a lung. There is much more to be done, such as placing a “chest tube,” a more extensive procedure that opens a path for drainage of fluids, re-inflation of the lung, and eventual full recovery. We’ll talk about that next time.
Joe Alton MD
“Dr. Bones”
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