Intraoperative somatosensory evoked potentials to facilitate peripheral nerve release

Intraoperative somatosensory evoked potential (SEP) monitoring: an updated position statement by the American Society of Neurophysiological Monitoring

Somatosensory evoked potentials (SEPs) are used to assess the functional status of somatosensory pathways during surgical procedures and can help protect patients' neurological integrity intraoperatively. This is a position statement on intraoperative SEP monitoring from the American Society of Neurophysiological Monitoring (ASNM) and updates prior ASNM position statements on SEPs from the years 2005 and 2010. This position statement is endorsed by ASNM and serves as an educational service to the neurophysiological community on the recommended use of SEPs as a neurophysiological monitoring tool. It presents the rationale for SEP utilization and its clinical applications. It also covers the relevant anatomy, technical methodology for setup and signal acquisition, signal interpretation, anesthesia and physiological considerations, and documentation and credentialing requirements to optimize SEP monitoring to aid in protecting the nervous system during surgery.

A novel approach of using brachial plexus blockade as an experimental model for diagnosis of intraoperative nerve dysfunction with somatosensory evoked potentials: a blinded proof-of-concept study

PURPOSE

Intraoperative nerve dysfunction has been difficult to investigate because of its rarity and unpredictable occurrence. The diagnostic test attributes of nerve function monitors have not been clearly defined. This proof-of-concept study aimed to assess the feasibility of using brachial plexus blockade (BPB) in awake patients as an experimental model for nerve dysfunction to characterize the diagnostic test attributes of somatosensory evoked potentials (SSEPs).

METHODS

We obtained baseline SSEPs and neurologic function in patients and subsequently placed BPBs (experimental model) to generate progressive states of nerve dysfunction. We monitored SSEP changes (index test) and neurologic symptoms (reference standard) simultaneously during the onset of BPB to determine the temporal relationships and diagnostic test attributes of SSEPs.

RESULTS

Brachial plexus blockade produced differential motor and sensory dysfunction that allowed simultaneous clinical and neurophysiologic assessment. One hundred and fifty-seven pairs of multiple data points from 14 patients were included for final analysis. The onset of abnormal SSEP signals almost always preceded the onset of neurologic symptoms. The sensitivities and specificities of SSEP to detect the impairment of power (motor rating score ≤ 4/5), cold sensation, and two-point discrimination were 100% and 67%, 99% and 55%, and 100% and 46%, respectively.

CONCLUSION

This study found that BPB can produce sufficient differential nerve dysfunction to allow adequate evaluation of the diagnostic test attributes of SSEPs as a nerve monitor. The results of this study may stimulate further work on refining intraoperative nerve dysfunction models and diagnostic nerve function monitors.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT03409536); registered 24 January 2018.

[Dealing with massive bleeding and associated perioperative coagulopathy: recommendations for action of the German Society of Anaesthesiology and Intensive Care Medicine]

Massive bleeding with coagulopathy and hemorrhagic shock poses a potential threat to life in numerous clinical settings. Optimal treatment including the prevention of exsanguination necessitates a standardized and interdisciplinary approach. Several studies have shown the importance of massive transfusion protocols and standardized coagulation algorithms to improve survival of severely bleeding patients and to avoid secondary complications. Thus, the Helsinki declaration for patient safety in anesthesiology demands the implementation of clinical practice guidelines for the treatment of patients requiring massive transfusion. This paper introduces a standardized algorithm for the treatment of patients with massive bleeding which was developed in consensus with the German Society of Anaesthesiology and Intensive Care Medicine (DGAI).

[Management of bleeding disorders in intensive care medicine]

Bleeding disorders are frequent in intensive care medicine, the most common form being acquired. Trauma, gastrointestinal bleeding, liver failure, hematologic malignancies, and adverse drug reactions play an important role. Moderate to severe hereditary bleeding disorders are usually known prior to the acute disease state, while mild hereditary forms may manifest for the first time in association with the acute stress condition. Generally, proper history taking and structured observation are decisive in order to conduct an appropriate diagnostic workup and initiate logical hemostatic management. One cannot always wait for laboratory results during continuous blood loss or conditions such as hypothermia and acidosis. In such cases, pathophysiological extrapolation of expected hemostatic disturbances is essential for timely hemostatic management.

C5-blocking antibody reduces fluid requirements and improves responsiveness to fluid infusion in hemorrhagic shock managed with hypotensive resuscitation

Hypotensive resuscitation strategies and inhibition of complement may both be of benefit in hemorrhagic shock. We asked if C5-blocking antibody (anti-C5) could diminish the amount of fluid required and improve responsiveness to resuscitation from hemorrhage. Awake, male Sprague-Dawley rats underwent controlled hemorrhage followed by prolonged (3 h) hypotensive resuscitation with lactated Ringer’s or Hextend, with or without anti-C5. Anti-C5 treatment led to an estimated 62.3 and 58.5% reduction in the volume of Hextend and lactated Ringer’s, respectively. In the subgroup of animals with a positive mean arterial pressure (MAP) response to fluid infusion following prolonged hypotension, anti-C5 treatment led to an estimated 4.7- and 4.1-fold increase in mean arterial pressure response per unit Hextend and lactated Ringer’s infused, respectively. We observed no significant postresuscitation metabolic differences between the anti-C5 groups and controls. Whether anti-C5 could serve as a volume-sparing adjunct that improves responsiveness to fluid administration in humans deserves further study.