Management of Ammonia Exposure

After an ammonia leak last night in Rosemount MN, one person died at the scene and several people were treated at our trauma center. Ammonia exposure is not very common, but can cause serious injury or death. This blog will review the facts about ammonia exposure and provide basic management tips for EMS and hospital personnel.

Nearly everybody who has worked with household cleaning products is familiar with the odor of ammonia. The gas is colorless with a potent, irritating smell. Ammonia gas is added to water to make cleaning solutions. Farmers use anhydrous ammonia to make fertilizer, which is a very pure form that is drawn to moisture. Ammonia is usually transported under pressure in steel tanker trucks in the form of a clear liquid.

From the medical standpoint, ammonia causes problems because it combines with water to form ammonium hydroxide, a strong alkali (base). When humans are exposed, an alkaline solution forms on any moist areas such as skin, eyes and mucus membranes. Inhaling the gas causes deeper exposure and burns in the respiratory tract. Higher concentrations of gas cause greater injury, with eye damage occurring very commonly that can lead to blindness.

Prehospital management:

• Protect yourself! A HAZMAT Hot Zone should be established with all personnel entering the zone properly protected with SCBA breathing apparatus and chemical protective suits.
• If victims can walk, lead them out of the Hot Zone. If not, drag them.
• Patients with exposure to gas only do not pose a risk to EMS personnel. Decontamination is not necessary, and they can be moved to the Support Zone.
• Pay attention to ABC as you would with any trauma patient.
• All other patients require decontamination in the Decontamination Zone as follows:
• 1. Flush exposed skin and hair for at least 5 minutes. Use warm water if possible to avoid hypothermia. Wash with soap and water if possible.
• 2. Irrigate eyes for at least 15 minutes. Remove contact lenses if possible.
• 3. Double-bag contaminated clothing and personal belongings.
• 4. For ingestions, do not induce vomiting, attempt to neutralize, or give activated charcoal. Conscious victims should be encouraged to swallow 4-8 oz of water or milk. Prepare the ambulance for possible toxic emesis prior to transport.

Transport patients to the nearest Burn Center or burn-capable hospital.

The receiving Emergency Department should prepare a separate area to receive any patients with residual contamination for additional decontam. Decontamination times and methods are similar to prehospital. Patients exposed only to ammonia gas do not need a separate area.

For additional information, click here to download a detailed document from the Agency for Toxic Substances & Disease Registry, a part of DHHS.

How to Rapidly Reverse Coumadin in Head Injured Patients

A growing number of adults, usually elderly, are taking Coumadin (warfarin) to manage chronic medical conditions or deep venous thrombosis. While warfarin is a very useful drug for these problems, it is notoriously difficult to maintain tight control of INR. If an individual on warfarin is involved in a fall or vehicular crash, bleeding complications can become life-threatening. A recent Journal of Trauma article shows that mortality more than doubles in elderly patient who are admitted awake after just falling from standing.

The key is to rapidly reverse an elevated INR. Vitamin K can be used to increase biological activity of several clotting factors, but this occurs over several hours. Plasma is also used, but there are several considerations. Many hospitals have only frozen plasma, and there may be a delay of 30 to 45 minutes to thaw it. Multiple units may need to be transfused in order to normalize higher INRs, which may cause volume overload in elderly patients with cardiovascular disease.

More recently, activated Factor VII (NovoSeven) has been used to aid rapid reversal of the INR. NovoSeven is FDA approved for only the following uses:

• Bleeding or surgery in hemophiliacs
• Bleeding or surgery in congenital Factor VII deficiency

Use of NovoSeven for rapid reversal of warfarin is an off-label use, and physicians must weigh the risks and benefits prior to use. It is also very costly, about $7000 per vial.

To download a printable copy of our protocol, click here.

PROTOCOL – PATIENTS ON WARFARIN WITH HEAD INJURY AND ABNORMAL CT SCAN

Check INR. Goal INR is 1.2-1.4

If > 1.4

• Give Vitamin K 10 mg IV
• Transfuse thawed plasma 15ml/kg (4-6 units)
• Consider NovoSeven
  Weight <>= 100kg – give 2mg IV

Repeat INR at 2hrs, 4hrs, 12hrs and 24 hrs after NovoSeven administration.

If INR increases to > 1.4, repeat plasma transfusion as needed.

Reference: J Trauma. 2009 Jun;66(6):1518-22; discussion 1523-4.

NOTE: This guideline is based on protocols in use at the Regions Hospital Level I Adult and Pediatric Trauma Centers. As with any potent drugs or procedures, undesired side-effects may occur. The individual physician prescribing these medications or procedures is solely responsible for the safety of his or her individual patient.

Pulmonary Embolism and DVT in Trauma

We have long assumed that pulmonary emboli start as clots in the deep veins of the legs (or pelvis), then break off and float into the branches of the pulmonary artery in the lungs. A huge industry has developed around how best to deal with or prevent this problem, including mechanical devices (sequential compression devices), chemical prophylaxis (heparin products), and physical devices (IVC filters).

The really interesting thing is that less than half of patients who are diagnosed with a pulmonary embolism have identifiable clots in their leg veins. In one study, 26 of 200 patients developed DVT and 4 had a PE. However, none of the DVT patients developed an embolism, and none of the embolism patients had a DVT! How can this kind of disparity be explained?

Researchers at the Massachusetts General Hospital retrospectively looked at the correlation between DVT and PE in trauma patients over a 3 year period. DVT was screened for on a weekly basis by duplex venous ultrsonagraphy. PE was diagnoses exclusively using CT scan of the chest, but also included the pelvic and leg veins to look for a source. A total of 247 patients underwent the CT study for PE and were included in the study.

Forty six patients had PE (39% central, 61% peripheral pulmonary arterial branches) and 18 had DVT (16 seen on the PE CT and 2 found by duplex). Of the 46 patients with PE, only 15% had DVT. All patient groups were similar with respect to injuries, injury severity, sex, anticoagulation and lengths of stay. Interestingly, 71% of PE patients with DVT had a central PE, but only 33% of patients without DVT had a central PE.

The authors propose 4 possible explanations for their findings:

1. The diagnostics tools for detecting DVT are not very good. FALSE: CT evaluation is probably the “gold standard”, since venography has long since been abandoned
2. Many clots originate in the upper extremities. FALSE: most centers do not detect many DVTs in the arms
3. Leg clots do not break off to throw a PE, they dislodge cleanly and completely. FALSE: cadaver studies have not show this to be true
4. Some clots may form on their own in the pulmonary artery due to endothelial inflammation or other unknown mechanisms. POSSIBLE

An invited critique scrutinizes the study’s use of diagnostics and the lack of hard evidence of clot formation in the lungs.

The bottom line: this is a very intriguing study that questions our assumptions about deep venous thrombosis and pulmonary embolism. More work will be done on this question, and I think the result will be a radical change in our use of anticoagulation and IVC filters over the next 3-5 years.

Velmahos, Spaniolas, Tabbara et al. Arch Surg. 2009; 144(10):928-932.

Personal Decisions are the Leading Cause of Death

A relatively obscure research paper published last December by Ralph Keeney at Duke University makes this startling claim: over half of the people who died in this country in the year 2000 did so because of their own personal decisions! If you look at current mortality statistics, the top four causes of death from year to year are heart disease, cancer, stroke and injury. We naturally look at this and think that these people had a heart attack or discovered a cancer or crashed their car. What these statistics fail to show is how the people really ended up with these conditions.

Keeney's paper looked beyond what was written on the death certificate and looked at how frequently personal choices caused these conditions. For example, smoking leads to heart disease, cancer, stroke, and high blood pressure, to name a few. Being overweight leads to heart disease, diabetes, high blood pressure, and many others. Inappropriate use of alcohol can lead to cancer, liver disease and a tendency to get into accidents.

The top causes of death were analyzed, looking at the percentage that could be caused by personal decisions such as smoking, diet, exercise, and use of alcohol or other drugs. A personal decision was defined as a situation where the individual could make a choice between two or more readily available alternatives (for example, smoking and not smoking) and that they had control over this choice. These choices are not necessarily easy to make because habits, social pressure, or genetic predisposition can make some alternatives hard to select.

Keeney found that about 55% of deaths in 2000 were caused by personal decisions. This compares to about 5% in the year 1900. This is due to the fact that the majority of the causes of death in 1900 were due to infectious diseases, and there were no antibiotics at the time to treat them.

What this paper shows us is that the need for high quality prevention activities is even greater that we thought, and that we may not be focusing on the right areas. Trauma centers habitually direct their prevention programs toward car seats, diving injuries, red light running, falls prevention and others. What we really need to focus on is personal choice, and teaching people how to make the right decisions. For trauma prevention, alcohol-related programs will probably give the greatest result since it is involved in so many of the top causes of death, even causes not related to trauma.

Trauma centers need to scrutinize their own prevention programs, and look critically at ways they can teach wise choices. It may be necessary to chage the focus of existing programs, or move to new programs that find ways to influence personal decision making. That way, trauma centers can have a hand not only in preventing certain types of injuries, but in directly decreasing the overall death rate as well.

Reference: Keeney RL. Operations Research 56:6, 1335-1347, 2008.

Do Trauma Patients Need A Rectal Exam?

It has long been standard operating procedure to perform a digital rectal exam in all major trauma patients. The belief has always been that valuable information about blood in the GI tract, the status of the urethra, and the neuro exam (rectal tone) could be gleaned from the exam.

Unfortunately, the exam also serves to antagonize or even further traumatize some patients, especially those who may be intoxicated to some degree. On a number of occasions I have seen calm patients become so agitated by the rectal that they required intubation for control.

So is it really necessary? A study in 2001 conducted over a 6 month period (1) showed that the rectal exam influenced management in only 1.2% of cases. The authors felt that there was some utility in 3 special cases:

• Spinal cord injury – looking for sacral sparing
• Pelvic fracture – looking for bone shards protruding into the rectum
• Penetrating abdominal trauma – looking for gross blood

A more recent 2005 study (2) was also critical of the rectal exam and found that using “other clinical indicators” (physical exam and other diagnostic study information) was at least equivalent, changing management only 4% of the time. They concurred with the first two indications above as well.

The Bottom Line: For most major trauma patients, the rectal exam is not worth the patient aggravation it causes. I still recommend it for the 3 special cases listed above, however, as there are no equivalent exams for these potentially serious patient problems.

References:
1. Porter, Urcic. Am Surg. 2001 May;67(5):438-41.
2. Esposito et al. J Trauma. 2005 Dec;59(6):1314-9.