7 October 2020 - Toxicology
Program
1000-1015: Welcome and recap
1015-1115: Hip and jaw reduction: Neil Cunningham
1115-1130: coffee
1130-1200: paracetamol OD: Matt Bray
1200-1230: Ca channel OD: Ben S
1230-1245: Break
1245-1315: ECG, Image, gas of the week with Sarah, Maria and Mark
1315-1400: SAQs with Sarah
Key Learning Points
Do you have the Austin’s toxicology app on your phone? If not, it is a must. It’s free and easy to use at the bedside as a memory aid. It’s also perfect for exam revision.
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The latest paracetamol guidelines are located here. This is the source of truth for current Australasian practice.
Dislocations
Head over to Neil’s website, dislocation.com.au for his explanations and video’s
ECG of the Week
Thanks Chris for the case this week. Please keep sending your cases through.
78M with HTN and OSA presented with 3 days of exertional SOB and lightheadedness which resolves with rest. There were no previous ECGs on our system.
BP 140/80. GCS 15
This ECG shows a bradycardia with the ventricular rate of 36bpm. The atrial rate is 72.
The PR interval is constant, but slightly prolonged. Every second P wave is not followed by a QRS complex so this suggests a Mobitz type II heart block. There is mild QRS prolongation that is secondary to a RBBB. The axis is normal without signs of a left anterior or posterior fascicular block.
This patient ultimately requires a PPM insertion.
Image of the Week
We didn’t get to the image last week so will discuss the knee X-rays this week. Please go back and submit your answers if you haven’t already.
Gas of the Week
This was a 42 yo male patient who came in overnight.
No medical hx beyond diverticular dx, no MH/eating disorder background, no regular meds.
For 'spiritual reasons' and 'to flush toxins' had gone 41 days fasting. No food, only water/water with a few drops of lemon juice for the first 3 weeks. Then tried drinking juice and soft drink because of metallic taste in mouth, but couldn't tolerate it. Had gone the last week without being able to keep any fluids down, vomiting 5-15x / day. 25kg weight loss, orthostatic hypotension, paresthesia to hands/lips as well.
Primary process: There is a predominant respiratory alkalosis evidenced by a low pCO2 and high pH and normal bicarb,
Secondary process: There is a subtle metabolic alkalosis based on a mildly raised base excess
Fencl-Stewart Approach
- SID = 40, although within the range of error, effect on base excess of - 2
- Lactate effect - 2
- Albumin effect is - 1
Sum effect = -5 yet measured effect is +5 so there is an unexplained alkalosis contributing +10
There is a concept of chloride unresponsive metabolic alkalosis. This can be caused by Bartter syndrome, Gitelman syndrome, severe hypokalaemia, hypermineralocotricoids (Conn’s) or increased renin. This entity is likely due to high renin/aldosterone where the body is attempting to retain sodium due to lack of dietary intake.
In this case, this is an unusual cause of a metabolic alkalosis.
Other features of this gas
Hyperlactataemia - ? Tissue hypo perfusion from shock, ? Organ failures
Hypokalaemia although expected K for this pH is 2.8
Hyperchloraemia - vomiting
Mild hypercalcaemia - likely due to dehydration
Hypophosphataemia and hypomagnesaemia likely due to poor dietary intake.