Caring for the hypotensive, massively bleeding, trauma patient requires prioritizing and management of the anesthesiologist’s resources. At our institution, these resources are usually an attending anesthesiologist and two residents of differing abilities based on their years of training.
The trauma surgeon, rightfully so, is interested in the patient’s metabolic status, and will usually want to know what the arterial blood gas results are. This query sets into motion a desire to insert an arterial line. Inserting the arterial line under conditions of hypotension, peripheral vasoconstriction, lack of easy access to the wrist, chaos, is difficult, often impossible, and it takes one of the anesthesia providers away from doing other things.
Expecting a trainee with little a-line experience to successfully insert an a-line under these conditions is unrealistic and counterproductive. Even skilled anesthesiologists will have difficulty cannulating a radial artery under these conditions. This is not the time to teach/learn a-line insertion.
An arterial line is nice to have. However, the automated blood pressure cuff is quite good at measuring blood pressure when there is blood pressure.
A venous blood gas, in my opinion, is as good as an ABG and the VBG is more quickly and easily obtained from an external or internal jugular vein in a devolving trauma scenario.
The VBG provides all the information that the surgeon and anesthesiologist need:
- The VBG pH will be 0.06 mmHg lower than the ABG
- The VBG pCO2 will be 6 mmHg higher than the ABG
- The normal VBG pO2 will be 40-50 mmHg, but the O2 saturation measured on the finger pulse oximeter will tell us if the patient’s paO2 is adequate or not
- All other VBG values, e.g. lytes, lactate, base excess, etc., are the same as those from an ABG
- Additionally, other blood draws, like type and screen, blood type confirmation tube, clotting studies are more easily obtain from the jugular veins when an a-line is not available
I draw my VBG from the EJ if I can see one or from the IJ if the EJ is not visible. I use a 25 guage, 1.5 inch needle, inserted 2 inches above the clavicle in the vicinity of the triangle formed by the sternomastoid muscles.
By inserting the needle 2 inches above the clavicle it is unlikely that the 1.5 inch needle will penetrate the pleura and cause a pneumothorax. Additionally, the small needle diameter is unlikely to cause any vascular injury and it is unnecessary to hold pressure to prevent any significant bleeding.