[Lab in the News] BC Children's Chemical Spill

This week, our BC Children's Hospital was treated to a Code BROWN, or major chemical spill of parafromaldehyde. Para-formaldehyde can cause skin and eye irritation, and can be harmful if inhaled. It is also highly flammable.


http://www.cbc.ca/news/canada/british-columbia/bc-children-hospital-chemical-spill-1.3259740

Each hospital drills every year in case of this occurrence, and the procedures in place seem to have been followed to the letter. No one was reported hurt, and the spill was contained in under two hours.

Just in case you aren't familiar with common protocol, each hospital usually has a color coded to indicate that a chemical spill has occurred to the staff without alarming patients or visitors. Once a Code Brown is called, there are processes in place to do some or all of the following:

- Summon security or someone trained to address the spill.
- Evacuate anyone who could come into contact with the spill, or fumes from the spill.
- Call in a HAZMAT team or fire fighters to address more dangerous chemicals.

That's all well and good, but when is a Code Brown called, and what should lab staff do directly after a spill?

First, lab staff need to determine if they should be calling a Code Brown, or cleaning it themselves. Questions to ask include:

Do you know what chemical was spilled?
What volumes are involved?
What are the hazards of the chemical that was spilled (Found in the MSDS kept on site by law)
Is there a Chemical Reaction or hazard present, and can the area be cordoned off?
Do you know where the spill kit is, and how to use it?
Make sure to inform your supervisor and close by staff about the spill before attempting to clean it up.

ALWAYS CHECK AND WEAR APPROPRIATE PPE BEFORE APPROACHING THE SPILL.

Some spills you will need breathing equipment, or special gloves. Do not make assumptions; always check the MSDS.

A Code Brown is called if there is a spill over a certain volume of chemicals or matter deemed low risk, or any amount of spill of high risk chemicals or gases. Each facility will have it's own categories.

Low Risk Spills: (Dealt with by lab staff, not HAZMAT/Code Brown)

This tends to include a chemical spill less than 500 mL of a known chemical that shows no visible chemical reaction (bubbling, hissing, gases emitting when in contact with surface spilled onto).

Example: Spilling 10 mL of 0.1M HCl onto a bench surface.

Intermediate Risk Spills: (Dealt with by security and lab staff, Code Brown called)

This includes chemical spills that are large volume and can't be handled by lab staff alone, that are not reacting with the surface spilled onto, and also are not emitting fumes. You would call a Code Brown in this case, and security would come and help you keep people off the area, and clean it up.

Major Risk Spills: (HAZMAT, Security, Lab Staff work together, Code Brown called, Evacuation)

Either the substance spilled is unknown, the volume of the spill is unmanageable, the chemical fumes/contact is dangerous, or there is known/visible reactions that are happening between the chemical and the spill surface.

This is where parafromaldehyde lies, if dealt with outside of a fumehood. It is both highly flammable and emits fumes that are harmful to humans if inhaled. It makes sense that the evacuated the hospital, and ensured no harmful fumes/risk of fire was transfered to staff and patients.

 

New in Serum Osmolality: Zander's Formula

Serum Osmolality and OGAP... two of the formulae chemistry techs can do in their sleep. We all know the standard textbook Worthley et al equations;

Serum Osmolality (all in mmol/L):

2 Sodium + Urea + Glucose + 1.2 Blood Alcohol

Osmolar Gap  

Measured Osmolality - Calculated Osmolality

To make it easier for doctors or nurses without a lab handy, many websites/apps are even set up to do the math, with the reference ranges and criticals on the side. We've used the same formula for more than twenty-five years.

Last year, 2013, Zander's Formula was released as a "better, more useful calculation" for osmolality.

Zander's Osmolality (all in mmol/L): 

(Sodium + Urea + Glucose + Potassium + Bicarbonate + Lactate +6.5)x0.985

How is it better? Not only does it show a much better correlation between calculated and measured, it also has the closest 95% limits of agreement, when compared to 36 other possible formulae, (including the Worthley.) 

This new formula also only uses analytes commonly found on a blood gas analyzer panel. This will enable, in the future, a calculated osmolar gap to be added on automatically to trauma panels, giving the clinician one more piece of the puzzle in differentiating metabolic acidosis.

This is important because with such improved accuracy of OGAP, we would reduce the necessity for follow up methanol or ethylene glycol testing on many of our trauma patients who present with elevated gaps due to renal failure/shock/lactic acidosis, thus speeding diagnosis. (Remember though, the measured osmolality MUST be done by freezing point method if looking for any types of alcohol, as vapour pressure methods don't detect volatile solutes such as ethanol/methanol)

That said, Zander's is built to be used broadly; it doesn't include ethanol contribution as a matter of course; you would have to add the 1.2(ALC) yourself, to rule out/confirm any gap being due to ethanol rather than methanol, mannitol, or any of the other usual suspects. Depending on your population and preferred use, it could do with some tweaking.

[Case Study] Bright Green Urine

Patient A is admitted for cardiac surgery on January 10. All his pre-op chemistry tests are normal, and he is cleared for surgery. His surgery is sucessful, and post-op blood and urine samples are submitted to check his status. His urine sample immediately drew notice upon arrival to the lab. Upon analysis, the urine showed:

Colour: Bright Green
Clarity: Clear
pH : 5.5
Specific Gravity: 1.015
Leukocytes: Negative
Hemoglobin: Trace
Protein: Negative
Ketones: Negative
Urobilinogen: Negative
Nitrite: Negative

Microscopic analysis confirmed the occasional red blood cell and 6-10 epithelial cells. No bacteria were seen.

The pre-operative urine sample was pulled, and the colour was a normal clear yellow with normal results.

But what was causing the urine to be so oddly coloured? Was it clinically significant? Upon investigation, the ward confirmed sample quality and a list of possible causal drugs were produced. Among those drugs was a short-acting, intravenous sedative-hypnotic agent by the name of Proprofol (Diprivan). Used to induce and maintain anesthesia or sedation, one of the more infrequent side effects (in < 1%) from Proprofol is a production of bright green urine. It is not clinically significant, and the colour change is known to cease once the proprofol is discontinued.

Other more common causes of the colour change are:

1. Methylene Blue: (Blue + Yellow = Green): used in treatment of malaria (third world countries due to cost), methemoglobinemia, cyanide poisoning, and cancer. Also a component of an older urinary analgesic.
2. Pseudomonas infection: This produces a deeper, forest green colour with a grapey smell.
3. Dietary changes: Examples are excess quantities of Clorets or Blue Listerine
4. Magnesium Silicate (Doan's pills): A NSAID used for back pain. OTC medication.
5. Medical imaging: Some dyes such as biliverdin are used to assist in in vivo scanning.

Medscape has done an article on similiar cases here.