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Anniken Haavind1, Olav Hevrøy1, Rune Hennig2,3, Lars Bjertnaes1,31Division of Intensive Care Medicine, Department of Anesthesiology; 2Department of Neurosurgery, University Hospital of North Norway; 3Department of Clinical Medicine (neurosurgery and anesthesiology), Faculty of Health Sciences, University of Tromsø, Tromsø, NorwayAbstract: Pneumonia, severe sepsis, and acute respiratory distress syndrome (ARDS) are frequent complications after head trauma. Recombinant human activated protein C (APC) reportedly improves circulation and respiration in severe sepsis, but is contraindicated after head injury because of increased risk of intracranial bleeding. A 21-year-old man with severe head injury after a car accident was endotracheally intubated, mechanically ventilated, and hemodynamically stabilized before transfer to our university hospital. His condition became complicated with pneumonia, septic shock, ARDS, coagulation dysfunction, and renal failure. In spite of intensive therapy, oxygenation and arterial blood pressure fell to critically low values. Simultaneously, his intracranial pressure peaked and his pupils dilated, displaying no reflexes to light. His antibiotic regimen was changed and ventilation was altered to high frequency oscillations, and despite being ethically problematic, we added APC to his treatment. The patient recovered with modest neurological sequelae.Keywords: activated protein C, acute respiratory distress syndrome, septic shock, severe head injury

Lars J Bjertnaes,1,2 Anton Hauge,3 Marianne Thoresen,3,4 Lars Walløe3 1Anesthesia and Critical Care Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, N-9037, Norway; 2Department of Intensive Care Medicine, University Hospital of North Norway, Tromsø, N- 9017, Norway; 3Division of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, 0317, Norway; 4Translational Health Sciences, University of Bristol, Bristol, UKCorrespondence: Lars J BjertnaesAnesthesia and Critical Care Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, N-9037, NorwayTel +47 77627001Fax +47 77626042Email lars.bjertnaes@uit.noBackground: Successful cardiopulmonary resuscitation after drowning or avalanche is often attributed to hypothermia-induced decrease in metabolism, which adapts the oxygen demand to the amount supplied under cardiac compression. Four decades ago, we speculated if oxygen-sparing mechanisms like those found in marine mammals, may improve cerebral oxygenation during acute airway blockade in humans. We investigated hemodynamic changes during steady state ergometer cycling with intermittent periods of apnea and face immersion (AFI) in ice-cold water. During AFI, heart rate (HR) dropped by 58% whereas average blood velocity (ABV) determined by means of a Doppler ultrasound velocity meter (UNIDOP University of Oslo, Oslo, Norway) fell by 85% in the radial artery and rose by 67% in the vertebral artery. Similar changes occured in radial artery ABV, albeit more slowly, when the test subject only held his breath while cycling. When he breathed via a snorkel during face immersion, HR remained unchanged while radial artery ABV fell transiently and subsequently returned to its pre-immersion level. These findings later were confirmed by other investigators. Moreover, a recent study revealed that the seal even has a system for selective brain cooling during the dive.Conclusion: Our research has confirmed prioritized cerebral circulation during AFI in cold water. We hypothesize that these changes may improve brain oxygenation due both to greater blood flow and possibly also to faster brain cooling, as demonstrated in diving seals.Keywords: apnea, breath-hold, cardiopulmonary resuscitation, diving response, hypothermia