Tag Archives: dogma

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Does Initial Hematocrit Predict Shock?

Everything you know is WRONG!

The classic textbook teaching is that trauma patients bleed whole blood. And that if you measure the hematocrit (or hemoglobin) on arrival, it will approximate their baseline value because not enough time has passed for equilibration and hemodilution. As I’ve said before, you’ve got to be willing to question dogma!

The trauma group at Ryder in Miami took a good look at this assumption. They drew initial labs on all patients requiring emergency surgery within 4 hours of presentation to the trauma center. They also estimated blood loss in the resuscitation room and OR and compared it to the initial hematocrit. They also compared the hematocrit to the amount of crystalloid and blood transfused in those areas.

Patients with lower initial hematocrits had significantly higher blood loss and fluid and blood replacement during the initial treatment period. Some of this effect may be due to the fact that blood loss was underestimated, or that prehospital IV fluids diluted the patient’s blood counts. However, this study appears sound and should prompt us to question the “facts” we hear every day.

Bottom line: Starling was right! Fluid shifts occur rapidly, and initial hematocrit or hemoglobin may very well reflect the volume status of patients who are bleeding rapidly. If the blood counts you obtain in the resuscitation room come back low, believe it! You must presume your patient is bleeding to death until proven otherwise.

Reference: Initial hematocrit in trauma: A paradigm shift? J Trauma 72(1):54-60, 2012.

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Needle Thoracostomy: Where To Put It?

This is another one of those “everything you know is wrong” posts. Since forever, we’ve been taught that an emergent needle thoracostomy should be placed in the second intercostal space, mid-clavicular line. But how do we know?

Once again, the crew at USC+LAC has taken a new look at something we take for granted. They studied thoracostomy insertion in 20 cadavers, using both the classic insertion site as well as a fifth intercostal space, mid-axillary line position.

They found that only 58% of classically placed needles entered the chest cavity, while 100% of the 5th intercostal space catheters were successful. The success rate in the classic position in males was 75%, but in females was only 17%. The authors speculate that the perfect success rate with the lateral approach was due to the absence of extra tissue over the second intercostal space (pectoralis muscle, breast tissue).

Bottom line: Always question dogma. Granted, there are some limitations with this study (using dead people, age and weight not available). Nevertheless, this correlates with my experience, especially when shorter (5cm long) catheters are used. Although I will not necessarily change my practice immediately until there’s a little more literature, I will keep this in mind for obese patients or in those where traditional placement doesn’t seem to be having the desired effect.

Related post:

Reference: Optimal positioning for emergent needle thoracostomy: a cadaver-based study. J Trauma 71(5):1099-1103, 2011.