It is hard to top the enjoyment of traveling the back roads in an RV. But just like boat, the constant maintenance can take a lot of the joy it. Things are constantly breaking, and the time you spend working on the RV is often more than you spend behind the wheel or camping out. This didn’t bother our patient, but unfortunately during one of his repairs he suffered a serious injury.
He had spent the last several weekends preparing his vehicle for the summer travels across the upper plain states. The refrigerator had not been cooling properly during his last trip, and he was determined to get it working. He felt for sure it was a coil in the boiler. Working alone, with the doors closed mind you, he carefully disassembled it. All of a sudden he was hit with with an envelope of noxious gas. He would tell us later he instantly knew the smell — ammonia.
He managed to get out of the door but stumbled down onto the driveway. He couldn’t stop coughing and became very short of breath. By the time he reached the hospital he was hypoxic and in significant respiratory distress. He was intubated and admitted to the ICU.
How RV Ammonia Refrigerators Works
There are 2 brands of refrigerators commonly found in RVs:
- Dometic RV refrigerator
- Norcold RV refrigerator
Both operate under the same principles. A sealed cooling element is heated either with a gas flame or an electric heating element. The cooling unit amounts to a series of tubes filled with an ammonia-based liquid. As heat is applied, the fluid circulates through the cooling unit drawing the heat out of the refrigerator.
Refrigerant grade anhydrous ammonia is a clear, colorless liquid or gas, free from visible impurities. It is at least 99.95 percent pure ammonia. Water cannot have a content above 33 parts per million (ppm) and oil cannot have a content above 2 ppm. Preserving the purity of the ammonia is essential to ensure proper function of the refrigeration system.
A strong ammonia smell inside the box, would indicate a leak in the evaporator section. If the unit has leaked for an extended amount of time the ammonia smell may no longer be present but you will probably hear a gurgling sound coming from the back of your refrigerator a few minutes after you turn it on.
Mechanism of injury
Inhalation of noxious gases and fumes, including nitric acid (solution of NO2 in water), sulfur dioxide (SO2), chlorine gas (Cl), and ammonia (NH3) can lead to acute injury by direct toxic affects on the oropharynx, larynx, trachea, and bronchial structures. This can cause mucosal sloughing and hemorrhage, which often manifests itself as coughing and hemoptysis.
However, even with relatively minor airway injury, the gases can condense and pool in the alveoli obliterating the capability for gas exchange resulting in further tissue damage and hypoxia. This can develop into ARDS (noncardiogenic pulmonary edema), irritant-induced asthma, or delayed onset of constrictive bronchiolitis (also known as bronchiolitis obliterans).
Bronchoscopy after ammonia inhalation
Our patient underwent direct laryngoscopy which demonstrated normal oropharynx and hypopharynx mucosa. On bronchoscopy he had moderate diffuse mucosal injury but only scant clear secretions.
|Figure 1. View of trachea and carina in a patient who suffered ammonia inhalation injury.|