Lab Values From Intraosseous Blood
The intraosseous access device (IO) has been a lifesaver by providing vascular access in patients who are difficult IV sticks. In some cases, it is even difficult to draw blood in these patients by a direct venipuncture. So is it okay to send IO blood to the lab for analysis during a trauma resuscitation?
A study using 10 volunteers was published last year (imagine volunteering to have an IO needle placed)! All IO devices were inserted in the proximal humerus. Here is a summary of the results comparing IO and IV blood:
- Hemoglobin / hematocrit - good correlation
- White blood cell count - no correlation
- Platelet count - no correlation
- Sodium - no correlation but within 5% of IV value
- Potassium - no correlation
- Choloride - good correlation
- Serum CO2 - no correlation
- Calcium - no correlation but within 10% of IV value
- Glucose - good correlation
- BUN / Creatinine - good correlation
Bottom line: Intraosseous blood can be used if blood from arterial or venous puncture is not available. Discarding the first 2cc of marrow aspirated improves the accuracy of the lab results obtained. The important tests (hemoglobin/hematocrit, glucose) are reasonably accurate, as are Na, Cl, BUN, and creatinine. The use of IO blood for type and cross is not yet widely accepted by blood banks, but can be used until other blood is available.
Reference: A new study of intraosseous blood for laboratory analysis. Arch Path Lab Med 134(9):1253-1260, 2010.
Tips For Trauma Pros: Seat Belt Sign
We see seat belt signs at our trauma center with some regularity. There are plenty of papers out there that detail the injuries that occur and the need for a low threshold for surgically exploring these patients. I have not been able to find specific management guidelines, and want to share some tidbits I have learned over the years. Yes, this is based on anecdotal experience, but it’s the best we have right now.
Tips for trauma professionals:
- Common injuries involve the terminal ileum, proximal jejunum, and sigmoid colon. My observation is that location in the car is associated with the injury location, probably because of the location of the seat belt buckle. In the US, drivers buckle on the right, and I’ve seen more terminal ileum and buckethandle injuries in this group. Front seat passengers buckle on the left, and I tend to see proximal jejunum and sigmoid injuries more often in them.
- Seat belt sign on physical exam requires abdominal CT for evaluation, regardless of age. The high incidence of significant injury mandates this test.
- Seat belt sign plus any anomaly on CT requires evaluation in the OR. The only exception would be a patient with minimal fluid only in the pelvis with an unremarkable abdominal exam. But I would watch them like a hawk.
- In patients who cannot be examined clinically (e.g. severe TBI), a rising WBC count or lactate beginning on day 2 after adequate resuscitation should prompt a trip to the OR. This is an indirect method for detecting injured bowel or mesentery.
- Laparoscopy may be used in patients with equivocal findings. Excessive blood, bile tinged fluid, succus, or lots of fibrin deposits on the bowel should prompt conversion to laparotomy. Tip: place all ports distant to the seat belt mark. The soft tissues are frequently disrupted, and gas may leak into this pocket prohibiting good insufflation of the peritoneal cavity.
- If in doubt, open the abdomen. It’s bad form to put in the scope, see something odd, and walk away. Remember, any abnormal finding after trauma is related to trauma until proven otherwise. It’s almost never pre-existing disease.
Fasciotomy Closure: VAC vs Shoestrings
Fasciotomy is the definitive management for compartment syndrome. But by definition, once you make the incision things are going to gape apart. If they don’t, hmmm, there probably wasn’t a compartment syndrome in the first place.
That’s the easy part. Now, how do you make the wound edges come together and achieve some kind of cosmetic result? Historically, a variety of techniques have been used. They include leaving it open to granulate, brute force sutures, progressive closures, and more recently, the VAC suction dressing.
This latter technique has really caught on, and there are a number of benefits. First, the suction can reduce tissue edema, which may facilitate quicker closure. Another big advantage is that this dressing can be changed every 3 days, as opposed to daily (or more) for conventional dressings.
The downsides: cost, and the fact that some people in the US don’t have insurance that covers home use of this device. This may drive up costs by increasing hospital length of stay.
But is it better than the other closure methods? A recently published paper from an orthopaedic and plastic surgical group in Greece details a randomized, prospective study comparing VAC assisted closure versus the shoelace technique.
Here are the factoids:
- 50 patients with 82 leg fasciotomy wounds were randomized over 5 years
- The VAC group had the device applied 3-6 days postop with a pressure of -125 torr. They were changed every 3 days.
- The shoelace group had the bands applied at the end of the operation. Tightening began 4-6 days postop and was then performed daily.
- Time to closure with the VAC was 19 days vs 15 days for shoelaces. This was a significant difference.
- Skin grafts were required to complete the closure in 6 VAC cases, but in none of the shoelace patients
- There were 6 wound infections in the VAC group vs 4 in the shoelace group (NS)
- Average daily cost in the VAC group was 135 euro, but only 14 euro for shoelaces
- The cost to add a skin graft in the VAC group added substantial additional expense
Bottom line: This is a nice comparison of two techniques that try to solve the wound closure problem using two different methods. The VAC reduces edema but does not shrink the wound, while shoelaces stretch the skin to close the wound but do nothing about edema. The VAC is slower and more expensive, and frequently requires an additional (and expensive) skin graft. Shoelaces are quicker and cheap. What to do? It would appear that wound shrinking methods are preferred. However, if edema is significant, apply a VAC first. Then switch to shoelaces once the edema has subsided for faster (and graft-less) closure.
Reference: Wound closure of leg fasciotomy: Comparison of vacuum-assisted closure versus shoelace technique. A randomised study. Injury 45(5):890-893, 2014.
Bystander CPR For People Not In Cardiac Arrest
CPR has increased the survival rate of patients suffering cardiac arrest, and early bystander CPR has been shown to double or triple survival. The sad truth is that CPR is not frequently performed by the general public. The American Heart Association has attempted to simplify CPR to the point that even untrained bystanders can administer chest compressions without a pulse check and without rescue breathing.
But what happens if that well-intentioned bystander starts CPR in someone who has not arrested? How often does this happen? Can the patient be injured?
The Medical College of Wisconsin reviewed the charts of all patients who received bystander CPR in Milwaukee County over a six year period. There were 672 incidents of bystander CPR. Of those cases, 77 (12%) were not in arrest when assessed by EMS personnel, and the researchers focused on those patients.
EMS response time averaged 5 minutes, and was greater than 10 minutes in only 2 cases. Average patient age was 43(!). The male/female ratio was just about 50:50, and the majority of the incidents took place in the home or residence.
Hospital records were available for further analysis in 72 of the patients. A quarter were sent home, a quarter admitted to a ward bed, and half were admitted to an ICU. Only 12 (17%) had a cardiac-related discharge diagnosis. The next most common discharge diagnoses were near-drowning, respiratory failure and drug overdose. Younger patients (<19) were usually near-drowning victims, and older patients (>54) were most commonly diagnosed with syncope. Five patients did not survive. Only one CPR injury was identified, which was charted as rhabdomyolysis “secondary to having received CPR” (a weak injury diagnosis, in my opinion).
Bottom line: The potential benefit of bystander CPR outweighs the risk of injury or performing it on a victim who is not in arrest. This study shows that, although these patients may not need CPR, they are generally very ill. Given the rapid EMS response times and the younger average age of the victims, no real injuries occurred. The new American Heart Association recommendations are beneficial and should be distributed widely.
Reference: The frequency and consequences of cardiopulmonary resuscitation performed by bystanders on patients who are not in cardiac arrest. Prehosp Emerg Care 15:282-287, 2011.