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used to stabilize the needle. Use the 60 cc (or the 10 cc) syringe to aspirate urine.
- Withdraw the needle once urine aspiration stops.
What Not To Do:
Do not make repeated passes in different directions.
Do not get the needle far from the bone.
Do not advance the needle too deep. In most average size adults, it is difficult to go too deep. However, do
not press the hub of the needle into the skin. In children, the bladder is higher and much closer to the skin.
What to look for when emptying the bladder:
- Suddenly emptying a large bladder (volumes >1000 ml) may precipitate a profound vasovagal reaction, so
empty the bladder with the patient lying down. To avoid a vasovagal reaction empty the bladder by
letting out 400 ml every few minutes. Drainage of extremely large bladders can cause rupture of bladder
mucosal veins that had been compressed by the urine, so do not be surprised if the urine turns bloody. - Some patients will have a marked increase in urine output after the bladder is decompressed. This
signifies a significant obstruction to the bladder that has resulted in some renal injury. The urine output
can be very high (e.g., 800 ml/hour). In most cases, the patient’s thirst mechanism may allow for adequate
hydration. If urine output is very high (>200 cc/hr), monitor the vital signs every hour and ask the
patient if they feel lightheaded. If the pulse rate becomes elevated (>100) or there are orthostatic
symptoms (lightheadedness) or decreased blood pressure and increased pulse from supine to standing
position, insert an IV catheter and give D5 1⁄2 NS. Infuse the crystalloid over the next 2 hours at a rate to
replace half the urine volume of the previous 2 hours.
Procedure: Portable Pressure Chamber
COL Paul Rock, MC, USAWhat: Portable hyperbaric (‘pressure’) chambers are fabric bags that can be internally pressurized to
create a hyperbaric (higher pressure) condition inside the bag. The higher pressure inside is generated and
maintained by a small hand-, foot- or battery-powered air pump. Hyperbaric environments are useful for
treating altitude illnesses because high pressure increases the oxygen available to the body. For a patient
inside the pressure chamber bag, increased air pressure has the same effect as a descent in elevation.
The difference between the air pressure outside and inside the chamber bag at high altitude determines the
amount of simulated descent that can be achieved for the patient. The higher the actual altitude, the greater
the pressure difference, and the greater the simulated descent. For most chamber bags, the difference in
pressure at 15,000 feet is the equivalent of a descent to an elevation of about 8,000 feet. Because the
pressure difference between the inside of the bag and the atmosphere is less at lower elevations, the degree
of simulated descent is less there. However, because descent of even a few thousand feet can be a life saving
treatment for some altitude illnesses, pressure bags are still useful at altitudes as low as 9,000 feet.
Portable pressure chambers are relatively lightweight (generally less than 15 lbs) and can be folded for easy
carrying in backpacks. They are commercially available in the civilian sector in several countries around
the world. Available chambers include the Gamow Bag and the Hyperlite chamber (USA), the CERTEC
(France), the PAC (Portable Altitude Chamber, Australia). They can be purchased or rented through many
outdoor/travel medical suppliers. The US military maintains no such chamber in the supply chain.
When: For temporary treatment of altitude illnesses (acute mountain sickness [AMS], high altitude cerebral
edema [HACE], and high altitude pulmonary edema [HAPE]) when descent or evacuation is not available,
or while waiting for evacuation. This treatment can also be used to treat decompression sickness (DCS)
and arterial gas embolism/pulmonary overinflation syndrome (AGE/POIS) in diving (see Dive Medicine). The
chamber’s weight allows the patient to be transported in the chamber, even when evacuated by plane.
What You Need: Required: Portable hyperbaric chamber (fabric ‘pressure chamber’ bag) with pressure