Page 56 - Ultrasonography in Prehospital and Emergency Medicine - Rein Ketelaars
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Chapter 2
ONSD
Both optic disc edema detected by fundoscopy and an increased optic nerve sheath diameter (ONSD) are indications of increased intracranial pressure (ICP).94 The ONSD can easily be measured using US, although the use of a UCA might enhance the recognition of relevant anatomy.95 ONSD measurements, using a cut-off value of 5.0 mm, have a sensitivity and specificity of 100% and 95% in predicting an elevated ICP compared to CT.96 Moretti et al. compared US to invasive ICP measurements. Using a cut-off value of 5.2 mm they found a sensitivity and specificity of 93.1% and 73.9% for an ICP ≥ 20 mmHg.97 More recently, Maissan et al. measured the ONSD in ICP-monitored traumatic brain injury (TBI) patients before, during, and after routine suctioning of the endotracheal tube leading to a transient ICP rise. With a cut-off value of 5.0 mm they found the sensitivity and specificity to be 94% and 98% for a rise in ICP.98
Like US in ischemic stroke, the benefit of prehospital ONSD measurements might be to start neuroprotective strategies, to determine the need for neurosurgical care, or to provide a prearrival notification. However, the evidence on prehospital feasibility and benefit is still negligible.
E – Injuries
Fractures
Dulchavsky concluded that non-physicians in the ED (cast technicians) can reliably diag- nose orthopedic injury with an accuracy of 94% after a brief PoCUS training. This was more reliable for fractures of the humerus, forearm, femur, and lower leg than for hand and foot fractures, and tendon injuries.99
Bozorgi et al. evaluated US in 108 ED patients with 158 fractures in the extremities. Overall sensitivity was 68.3%. Sensitivity for femoral fractures and humeral fractures was 100% and 76.2%, respectively. The detection of intra-articular fractures was the most difficult with a sensitivity of only 48%.100
In the civilian prehospital setting, PHUS for fractures is probably feasible. It is useful for (long) bone fractures in the upper and lower arm, and leg. Advantages in the prehospital setting could be early reduction and splinting, triage, selecting the best destination provided with a specific prearrival notification.
