First Author: C.Skevas GERMANY
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To scrutinize if ocular ultrasound (OUS) may be established as a standard diagnostic tool in non-specialized intensive care and neurological rehabilitation units to screen for ocular bleedings and thus preventing worse clinical outcome with visual impairment. Primary endpoint of this study was description of sensitivity, specificity, positive and negative predictive value and accuracy of ocular ultrasound in the detection of TS. The secondary endpoint was description of the learning curve for the detection of TS by ocular ultrasound.
The study was performed at the university clinic Eppendorf in Hamburg
All patients admitted with the diagnosis of SAH in a 14 month period were classified as potential candidates for this study. A standard ultrasound system (General Electrics, Vivid S6; GE 8L-RS, General Electrics Healthcare, Chalfont St Giles, UK) with high-resolution linear probe (10 MHz) was used to simulate an examination in regular care hospitals outside high specialized medical centres. Standard water-soluble ultrasound transmission gel was applied to the closed eyelid of the patient so that the transducer did not touch the eyelid avoiding any pressure to the ocular bulb .
Investigator I detected 11 out of 21 IOH with OUS (sensitivity 52.4%, positive predictive value 57.9%), while 75 out of 83 eyes without IOH were stated to have no TS (specificity 90.4%, negative predictive value 88.2%, overall accuracy 82.7%;). In 8 eyes IOH was diagnosed by OUS without the existence of TS (false positive) and in 10 eyes TS was not detected by OUS (false negative). Investigator II was found to have a specificity of 100% (83 out of 83 eyes) with a negative predictive value of 84.7% and a sensitivity of 21.1% (4 out of 19 IOH; 3 vitreous and 1 retinal haemorrhages) with a positive predictive value of 100% (an accuracy of 85.3%). Specificity was 89.2%, and negative predictive value of OUS in dense VH was 97.6% for investigator I (with an accuracy of 88.5%). For investigator II, the rate was slightly higher, with a specificity of 100% and negative predictive value of 94.9% (with an accuracy of 95.1%). Sensitivity and positive predictive value increased in both investigators (investigator I; sensitivity 81.8%, positive predictive value 47.4%, investigator II; sensitivity 44.4%, positive predictive value 100%).
Indirect funduscopy is the gold standard for diagnosing TS, but iatrogenic mydriasis may mask life threatening complications, especially in neurocritically ill patients: Our results have shown that OUS as a bedside, non-invasive tool is of high diagnostic value and provides high accuracy detecting ocular pathologies. This is of special interest to neuro-intensive care and neurological rehabilitation units, as OUS is not routinely performed in SAH patients, where IOH followed by temporary or permanent visual acuity may affect many patients. Our study has confirmed that OUS is a safe and useful technique in diagnosing pathological changes of the ocular globe. Its ease of handling is accompanied by a fast accelerating learning curve, further improving diagnostic reliability. This should encourage neurointensive care physicians to become familiar with OUS to diagnose IOH, thereby differentiating between a pathology requiring immediate ophthalmologic consultation (such as retinal detachment and intraocular foreign bodies) from those findings (such as vitreous haemorrhage or retinal haemorrhage) which can be followed up on an outpatient basis:. In this context, ocular ultrasound is a very important tool to augment the diagnostic capabilities of neurointensive care and neurological rehabilitation units.