Wednesday, December 11, 2013

The Breaking Point - Rib Fracture Risk Stratification

The Gist:  Rib fractures are common and may be associated with significant injury and sequelae.  While rib fractures, even in elderly, don't necessitate transfer to Level I trauma centers, have a low threshold for ICU admission for aggressive pulmonary treatment and analgesia, especially in those with multiple injuries, older patients, some patients with 3+ rib fractures, inadequate pain control/pulmonary toilet, or patients with poor baseline health status (note: based on analyses of largely observational studies without controlled data on outcome differences in). Engage in shared decision making according to the patient's individual situation and check out this podcast by EAST for a Free Open Access Medical Education (FOAM) summary.

The Case: A 62 y/o male with a 50 pack year history of smoking presents as a trauma transfer to Janus General's Level I trauma center after a fall off of a horse, no loss of consciousness, GCS 15 with chest pain. BP 132/68, HR 78, O2 97% RA. He has exquisite tenderness over his right lateral chest wall, some pain and discomfort at rest, exacerbated by deep breathing and movement, and is accompanied by a chest CT scan demonstrating a mildly displaced fracture of the lateral 5th rib, non-displaced fractures of ribs 6-7th posteriorly and a tiny collection of fluid in the right base.
  • Where should I send this patient?  Home-he seems to be ok presently without significant other traumatic stigmata? The floor-his saturations are good, his pain seems to be controllable and he's not that old?  The ICU?
This case represents a common scenario encountered on my trauma surgery rotation and in the ED, and probably similar to other systems as rates of rib fractures in trauma patients reported at 10%[1].  The disposition varied based on the attendings involved and the outcomes, as I followed along for the month, were often surprising.  The initial "sick or not sick" impression didn't necessarily cut it with regards to assessment.  How might I better stratify these patients in the ED to advocate for appropriate disposition?

Risk Stratification - Why It May Matter
Rib fractures are associated with significant morbidity (30-50%) and mortality (~10%) [3,8,9].  It is clear that rib fractures can herald badness as they may signal underlying injury - pulmonary contusion, hemothorax, pneumothorax, or intra-abdominal injury [3].  Additionally, these patients are prone to develop pneumonia (on their own or after mechanical ventilation), which is associated with morbidity and mortality.  For example, a review of the literature demonstrated OR for mortality of 5.24 (95%CI 3.51–7.82) in rib fracture patients with pneumonia versus those without [4].

So, these patients present across a broad spectrum of injury severity (isolated rib fractures vs multiple traumas) and have a decent chance of not doing well, may require significant analgesia, and, depending on who you talk to can go home, to the floor, the ICU, or the OR.  As much of the morbidity/mortality is not evident immediately, risk stratifying, in the absence of a crystal ball, is important.

The breadth of literature suggests that older age is associated a worse prognosis in patients with rib fractures.  For example, this systematic review and meta-analysis found an OR of 1.98 (95%CI 1.86–2.11) for mortality in blunt chest trauma patients >65 y/o compared with younger cohorts  [4].  This makes sense as older patient often have:
  • weaker muscles of respiration
  • decreased physiologic reserve
  • less elasticity of lungs (decrease in volumes, inspiratory/expiratory forces)
  • decreased mucociliary clearance [5] 
These factors often create a great setup for pneumonia, which is associated with the aforementioned badness.   Additionally, older patients may have comorbidities that may predispose them to complications which, result in additional morbidity/mortality [6,7].

Battle et al analyzed data from a retrospective cohort of blunt chest trauma patients and found that the following co-morbidities are associated with complications from rib fractures:
  • Chronic lung disease 3.3 (95% CI 1.6–6.8) - already compromised lungs with set-up for pneumonia
  • Pre-injury anticoagulant use 2.3 (95% CI 1.1–4.8) - signifying underlying disease or propensity to develop hemothorax
  • Oxygen sat < 90% 5.0 (95% CI 1.0–25.7) - sicker patient [7]
Congestive heart failure has also been shown to be associated with an OR of 2.62 (95%CI 1.93–3.55) for mortality [4].

In addition, patients with other traumatic injuries fare worse if they also have rib fractures as they may be predisposed to thrombosis, decreased pulmonary reserve, compromised hemostasis, head injury, and foci of infection [3,4].

How about the number of rib fractures? 3? 6?
Mortality has been quoted as 19% for each rib fracture, but note that this statistic comes from a retrospective review where the OR for mortality was calculated as 1.19 for each rib fracture, with no confidence intervals reported [2].  According to EM texts, elderly patients with 6+ rib fractures should be admitted to the ICU [8,9]. A review of the literature, however, demonstrates that there's no clear answer but somewhere between 3-6 rib fractures is associated with more badness.
  • Lee et al wrote a paper proclaiming that 3+ rib fractures exists as an indication for transfer to a trauma facility.  In this data review, patients with >3 rib fractures had higher injury severity scores - a subgroup of patients with 3+ rib fractures who may benefit from trauma center care due to their potential underlying injuries and complications [10].  
    • Limitations: no outcome data. 
  • A review of the National Trauma Data Bank data demonstrated that mortality does increase with rib fractures but noted that the tipping point for mortality peaked at 6+ ribs with mortalities of 11.41% (n=1771) for 6 rib fractures, 15.03% (n=1114) for 7 rib fractures, and 34.42% (n=1994) for 8 rib fractures [3].
This paper asserts that patient's with more rib fractures are more likely to have underlying traumatic injuries, which is used as justification for a necessary Level 1 trauma center transfer.  One can assume that trauma professionals who treat a copious quantity of rib fractures may provide more targeted care to the patients, including employment of modalities such as epidural analgesia, NIV, and surgical fixation, outcome data for this is missing.  It's not clear that the patients couldn't receive intense pulmonary therapy and analgesia at other centers.

Limitation: Not all rib fractures are created equal and the number doesn't reflect the nature of the fracture, displacement, or presence of hemo/pneumothorax.
Is it a clear algorithm?
Just because some patients do poorly, this doesn't mean that all patients are high risk. Some patient can certainly be discharged or admitted to low acuity settings, provided they have good follow up and analgesia.  Afterall, hospitalization and medical interventions have associated complications and costs.

Chauny et al demonstrated that in their cohort of patient with rib fractures felt well enough to be discharged from the ED, pneumonia within the first two weeks was relatively uncommon at 0.6% of study population (n=6) [11]. So, it appears that discharge is safe in some patients, even those with 3 rib fractures but this is where clinical assessment comes into play.

  • Of note, very few in cohort (n=86; 8%) had 3+ confirmed rib fractures
  • Patients followed up by emergency physicians and research physicians at 1, 2 weeks, with AP chest x-rays, and by telephone at 4, 12 weeks.  This follow up certainly is not guaranteed in a good deal of our patient population and could have led to over-calling of pneumonia or overall more aggressive care.
  • Very few patients had outcome of interest.
Consider using an incentive spirometer to gauge inspiratory effort/volume at the bedside as part of assessing how the rib fractures may be contributing to the patient's overall status.

1. Ziegler DW, Agarwal NN. The morbidity and mortality of rib fractures. J. Trauma. 1994;37(6):975–9.
2.  Bulger EM, Arneson M a, Mock CN, Jurkovich GJ. Rib fractures in the elderly. J. Trauma. 2000;48(6):1040–6
3.  Flagel BT, Luchette F a, Reed RL, et al. Half-a-dozen ribs: the breakpoint for mortality. Surgery. 2005;138(4):717–23; discussion 723–5.
4.  Battle CE, Hutchings H, Evans P. Risk factors that predict mortality in patients with blunt chest wall trauma: a systematic review and meta-analysis. Injury. 2012;43(1):8–17.
5.  Callaway DW, Wolfe R.  Geriatric Trauma.  Emerg Med Clin N Am 25 (2007) 837–860
6.  Harrington DT, Machan PB, Zacharias N. Factors associated with survival following blunt chest trauma in older patients: results from a large regional trauma cooperative.Arch Surg. 2010 May;145(5):432-7.
7. Battle CE, Hutchings H, James K, Evans PA. The risk factors for the development of complications during the recovery phase following blunt chest wall trauma: a retrospective study. Injury. 2013;44(9):1171–6.
8.  Eckstein M, Henderson S.  "Thoracic Trauma." Rosen's Emergency Medicine 7th ed. p. 387-388.
9.  Brunett P, Yarris L, Cevik A.  "Pulmonary Trauma." Tintinalli's Emergency Medicine.  7th ed. p1756-1757.
10 . Lee RB, Bass SM, Morris JA, MacKenzie EJ. Three or more rib fractures as an indicator for transfer to a Level I trauma center: a population-based study. J. Trauma. 1990;30(6):689–94.
11.  Chauny J-M, Émond M, Plourde M, et al. Patients with rib fractures do not develop delayed pneumonia: a prospective, multicenter cohort study of minor thoracic injury. Ann. Emerg. Med. 2012;60(6):726–31. 

1 comment:

  1. As best I can tell, most of these studies used AP CXR to diagnose rib fractures(?). With increased sensitivity of CT (and probably ultrasound as well), CXR rib fracture != CT rib fracture. An important distinction when risk stratifying.