Head up position lowers intracranial pressure in a human cadaver model of cardiopulmonary resuscitation [poster]
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Introduction: Recent swine studies demonstrate the head up position (HUP) during cardiopulmonary resuscitation (CPR) improves blood flow to the brain and cerebral perfusion pressure (CePP). With HUP in pigs, cerebral venous drainage increase and intracranial pressure (ICP) decreased. These observations have not been demonstrated in humans. Hypothesis: We hypothesized ICP would decrease during HUP CPR versus supine position (SUP) in a human cadaver model of CPR. Methods: Six fresh recently deceased human cadavers, bequeathed to science were prepared by flushing the circulatory system with Metaflow, a blood clot dissolver. High fidelity Millar pressure catheters were used to measure hemodynamics. Active compression decompression CPR with an impedance threshold device (ResQCPR, Zoll Minneapolis) was performed in the SUP and HUP positions. Asynchronous ventilation was provided at rate of 10/min and a 600 ml tidal volume. Data expressed as mean +/- SD. A paired Student’s t-test was used to determine significance. Results: With CPR, we observed similar changes in arterial pressure and ICP as observed in pigs. During SUP CPR, mean (+/- SD) compression and decompression phases ICP (mmHg) were 0.5 +/- 3.2 and -1.1 +/- 4, respectively. With HUP CPR, the ICP were -7.7 +/- 5 and -8.3 +/- 3, respectively (p=0.038 comparing SUP versus HUP ICP values, respectively). The cerebral perfusion pressure (CerPP) (aortic minus ICP) was 23.5 +/- 10.2 SUP and 41.3 +/- 19.8 HUP, respectively (p=0.018). Representative pressure tracings are shown. The study is limited, as left to right capillary flow is poor in human cadavers. However, hemodynamic findings were qualitatively similar to pigs undergoing CPR and in pig cadavers perfused with heparinized saline 3 h and 24 h after death. Conclusions: The effect of gravity on ICP and CerPP in human cadavers during HUP CPR was qualitatively similar to what is observed in animals. These findings confirm that ICP will likely decrease in humans during HUP CPR.