Background: Modern human patient simulators (HPSs) could be used for researching critical scenarios such as apnea oxygenation. We aimed to study the use of a high-fidelity HPS to assess prolonged apnea using various oxygenation strategies with a simple high-flow nasal cannula (15 L/min). Methods: An experimental simulation study using an HPS (CAE Healthcare™) was conducted after obtaining approval from the Institutional Review Board. The HPS responded according to real-time physiologically modeled responses to external gases, such as oxygen (O2). Apnea experiments were performed with different physiological settings, such as shunt fraction (5%) and O2 consumption (250, 500, and 750 ml/min). The following four apnea experiments were conducted: no oxygenation (NO), apnea oxygenation alone (AO), preoxygenation alone (PO), and para-oxygenation (PAO). The time to 92%, 75%, and 50% saturation was recorded. Alveolar and arterial gas levels were recorded till 50% saturation. Results: At 250 ml/min, PO (1121 s) and PAO (1274.5 s) had a significantly longer time to 50% saturation (400% increase) compared to NO (222.5 s) and AO (239 s). A similar trend was observed for the time to 92% and 75% saturation. At higher O2 consumption rates, a shorter time to desaturation was observed. Conclusions Apnea trends in the HPS correlated with similar prior human experiments. AO without preoxygenation was found to provide no additional benefit. Preoxygenation with high-flow O2 via nasal cannula prolonged the time to desaturation in the PAO more than PO scenario. Therefore, HPSs can be used in future studies where patient safety is a concern.

INTRODUCTIONThe sciatic nerve is the largest nerve, with a long course in the inferior extremity. Its division into the tibial and common peroneal nerves can occur at any level from the sacral plexus to the inferior part of the popliteal space. These anatomical variations may contribute to clinical conditions such as piriformis syndrome, sciatica and coccygodynia.

METHODSThis study was performed on cadavers in order to study the level of sciatic nerve division. The inferior extremities of 43 cadavers were classified into six groups depending on the level of sciatic nerve division in the gluteal region, the upper, middle and lower parts of the back of the thigh, and the popliteal fossa.

RESULTSThe highest incidence of sciatic nerve division (40.7 percent) was observed in the lower part of the posterior compartment of the thigh. In 34.9 percent of the specimens, the sciatic nerve was divided into tibial and common peroneal nerves in the popliteal fossa. 16.3 percent of extremities showed sciatic nerve division proximal to its entrance in the gluteal region.

CONCLUSIONIn sciatic nerve neuropathies, the extent of neurological deficits depends on the level of sciatic nerve division. Sciatic nerve division into tibial and common peroneal components at a higher level can result in the involvement of only one out of the two divisions from sciatic neuropathy. It can also result in a failure of the sciatic nerve block while performing popliteal block anaesthesia.

Cadaver ; Female ; Humans ; India ; Lumbosacral Plexus ; pathology ; Male ; Models, Anatomic ; Models, Neurological ; Piriformis Muscle Syndrome ; pathology ; Reproducibility of Results ; Sciatic Nerve ; anatomy & histology ; physiopathology ; Sciatica ; pathology ; Tibia ; innervation ; pathology