Well-established in the field of bioelectronic medicine, Spinal Cord Stimulation (SCS) offers an implantable, nonpharmacologic treatment for patients with intractable chronic pain conditions. Chronic pain is a widely heterogenous syndrome with regard to both pathophysiology and the resultant phenotype. Despite advances in our understanding of SCS-mediated antinociception, there still exists limited evidence clarifying the pathways recruited when patterned electric pulses are applied to the epidural space. The rapid clinical implementation of novel SCS methods including burst, high frequency and dorsal root ganglion SCS has provided the clinician with multiple options to treat refractory chronic pain. While compelling evidence for safety and efficacy exists in support of these novel paradigms, our understanding of their mechanisms of action (MOA) dramatically lags behind clinical data. In this review, we reconstruct the available basic science and clinical literature that offers support for mechanisms of both paresthesia spinal cord stimulation (P-SCS) and paresthesia-free spinal cord stimulation (PF-SCS). While P-SCS has been heavily examined since its inception, PF-SCS paradigms have recently been clinically approved with the support of limited preclinical research. Thus, wide knowledge gaps exist between their clinical efficacy and MOA. To close this gap, many rich investigative avenues for both P-SCS and PF-SCS are underway, which will further open the door for paradigm optimization, adjunctive therapies and new indications for SCS. As our understanding of these mechanisms evolves, clinicians will be empowered with the possibility of improving patient care using SCS to selectively target specific pathophysiological processes in chronic pain.

(J Clin Anesth. 2018;44:50–56) Standardized hospital protocols that address severe postpartum hemorrhage (PPH), or estimated blood loss >1500 mL following delivery, generally follow principles of empiric resuscitation, favoring early transfusion of high volumes of fresh frozen plasma, packed red blood cells, and platelets. However, it has been suggested that blood product resuscitation should be individualized and adjusted according to the results of point-of-care viscoelastic testing (PCVT). In the present study, the authors compared clinical outcomes [volume of transfused blood products, rate of volume overload, and rate of intensive care unit (ICU) admission] and hospital costs for patients with severe PPH managed with and without PCVT-guided transfusion protocol.

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