530 Electromagnetic Interference with Protocolized Electrosurgery Dispersive Electrode Positioning in Patients with Implantable Cardioverter Defibrillators
During a surgical procedure, the function of an implantable cardioverter defibrillator may be disrupted by electromagnetic interference, most frequently resulting from monopolar electrosurgery. Failure to prevent or mitigate the effects of electromagnetic interference might lead to patient injury and even increase mortality. The risk of intraoperative right ventricular lead electromagnetic interference from monopolar electrosurgery was evaluated in a single-center, prospective cohort study of 144 subjects with protocolized positioning of a conventional electrosurgery unit dispersive electrode in patients undergoing noncardiac surgery and of an under-body dispersive electrode in patients undergoing cardiac surgery. Intraoperative electromagnetic interference of any detected rate or duration occurred in 14 of 70 patients (20%) having noncardiac surgery above the umbilicus, in 1 of 40 patients (2.5%) having surgery below the umbilicus, and in 23 of 34 patients (68%) having cardiac surgery. See the accompanying Editorial View on page 523.
550 Incidence, Severity, and Detection of Blood Pressure Perturbations after Abdominal Surgery: A Prospective Blinded Observational Study
Perioperative hypotension is strongly associated with myocardial injury, acute kidney injury, stroke, and mortality, and postoperative hypertension is associated with increased risk of bleeding, myocardial injury, and stroke. Because vital signs on surgical wards are usually obtained at 4- to 6-h intervals, detection of hemodynamic perturbations can be delayed or missed. The incidence and severity of both hypotension and hypertension during the first 48 postoperative hours were continually assessed in 312 adults recovering from elective abdominal surgery; detection of postoperative hypotension and hypertension by continuous versus periodic (routine vital sign assessments, usually at 4-h intervals) was compared. Continuous monitoring detected 75 patients (24%) who had contiguous episodes of mean arterial pressure less than 70 mmHg that lasted at least 30 min, 16 of whom (23%) were missed by routine vital sign assessments. Continuous monitoring also identified 41 patients (13%) with mean arterial pressure more than 125 mmHg for at least 30 contiguous minutes, 40 of whom (98%) were missed by routine vital sign assessments.
572 Quality of Life and Lung Function in Survivors of Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome
Acute respiratory distress syndrome is an inflammatory condition with diffuse injury to the alveolar-capillary barrier, leading to hypoxemic respiratory failure. Mechanical ventilation is a lifesaving maneuver, but the most severe cases require extracorporeal membrane oxygenation to guarantee vital gas exchange and protective ventilation. A prospective longitudinal cohort observational study of 84 patients with acute respiratory distress syndrome who were admitted to an intensive care unit between 2013 and 2015, 34 of whom (40%) received extracorporeal membrane oxygenation whereas 50 (60%) did not, was conducted to compare outcomes of patients treated with either extracorporeal membrane oxygenation or conventional treatment. Overall, 58 patients (69%) were discharged alive from the intensive care unit: 26 extracorporeal membrane oxygenation patients (76%) and 32 non–extracorporeal membrane oxygenation patients (64%). At 1-yr follow-up, 50 (62%) were alive: 22 extracorporeal membrane oxygenation patients (66%) and 28 non–extracorporeal membrane oxygenation patients (59%). Although respiratory function tests and lung imaging showed an almost complete functional recovery in both groups, non–extracorporeal membrane oxygenation patients reported more fatigue, weakness, limitation in daily activities, and hardship in return to previous life. See the accompanying Editorial View on page 528.
581 Neutrophil Extracellular Traps Are Elevated in Patients with Pneumonia-related Acute Respiratory Distress Syndrome
Neutrophil extracellular traps are extracellular fibers composed of DNA, histones, and granule-derived proteins such as elastase or myeloperoxidase released by neutrophils during a process called NETosis. Neutrophil extracellular traps can trap and kill extracellular pathogens and have been shown to be beneficial during infections but may also cause tissue injury. The hypotheses that neutrophil extracellular traps are produced in the lungs of patients with pneumonia-related acute respiratory distress syndrome (ARDS) and associated with regional neutrophil infiltration, and that bronchoalveolar neutrophil extracellular traps concentrations are associated with poorer outcome, were tested in 35 patients with moderate-to-severe pneumonia-related ARDS and 4 control patients undergoing bronchoscopy with bronchoalveolar lavage. ARDS patients had both six times higher bronchoalveolar than circulating neutrophil extracellular traps concentrations and higher bronchoalveolar concentrations than controls. The kinetics of bronchoalveolar, but not serum, neutrophil extracellular traps was stable over the first week of ARDS and bronchoalveolar neutrophil extracellular traps concentrations were highly correlated with lung neutrophil infiltration and bronchoalveolar interleukin-8 concentrations. Broncho-alveolar neutrophil extracellular traps concentrations were not significantly associated with the duration of mechanical ventilation.
560 Propofol Anesthesia Increases Long-range Frontoparietal Corticocortical Interaction in the Oculomotor Circuit in Macaque Monkeys
Electroencephalography studies have found that anesthetics, including propofol, functionally disconnect frontal cortical inputs from other cortical areas, particularly the parietal lobe. This decrease in functional connectivity has been interpreted as suppression of cortical feedback contributing to the anesthetized state, which might suggest anesthetics selectively suppress synapses from higher-order areas. It has also been reported using human local field potential data that slow-wave oscillations are fragmented and incoherent at a distance. Data from a publicly available repository of macaque monkey electrocorticography were analyzed to determine whether propofol not only decreases frontoparietal functional connectivity but also dissociates activity in two cortical areas involved in oculomotor behavior that have particularly potent reciprocal anatomic projections: the frontal eye field and the lateral intraparietal area. The opposite was observed: certain interactions, including coherent slow-wave oscillations and slow-wave-ß phase-amplitude coupling, increased in cortical areas with known anatomic projections from one to the other. These increases in coupling between cortical areas appeared to depend on the projection anatomy. See the accompanying Editorial View on page 526.
620 Lung- and Diaphragm-protective Ventilation in Acute Respiratory Distress Syndrome: Rationale and Challenges (Clinical Focus Review)
Mechanical ventilation can injure both the lung and the diaphragm, leading to substantial morbidity and mortality in ventilated patients. While the importance of lung-protective ventilation is well established, the concept of diaphragm-protective ventilation is an important but unproven new paradigm in the field. A novel approach to mechanical ventilation in the intensive care unit integrating both diaphragm- and lung-protective measures has the potential to affect the duration of mechanical ventilation, prevent long-term disability, and increase survival after acute respiratory failure. The present review outlines the basic mechanisms responsible for lung and diaphragm injury in relation to the presence or absence of spontaneous breathing, then proceeds to set out key targets for a strategy aiming to avoid both forms of injury with the ultimate goal of improving survival and accelerating liberation from mechanical ventilation. The approach proposed aims to strike a careful balance between potentially injurious insufficient respiratory effort and potentially injurious excessive effort while maintaining the overarching goal of ventilation to support homeostasis and recovery.
634 Contribution of Baroreceptor Function to Pain Perception and Perioperative Outcomes (Review Article)
Baroreceptors are mechanosensitive elements of the peripheral nervous system that maintain homeostasis by coordinating physiologic responses to external and internal stimuli. Although it is recognized that carotid and cardiopulmonary baroreceptor reflexes modulate autonomic output to mitigate excessive fluctuations in arterial blood pressure and to maintain intravascular volume, increasing evidence suggests baroreceptor activity modulates the perception of pain. The review begins with a consideration of evidence suggesting a role for baroreflex regulation of pain perception, including the influence of arterial and venous blood pressure on pain perception, the relationship between baroreflex stimulation and pain perception, and the physiologic mechanisms mediating baroreflex inhibition of pain. The clinical implications of impaired baroreceptor-mediated pain modulation are then reviewed, including the relationship between baroreceptor dysfunction and chronic musculoskeletal pain and between baroreflex dysfunction and inflammatory mediated pain as well as perioperative pain. The review concludes with considerations of the association of medical and health conditions with baroreceptor sensitivity and whether baroreceptor sensitivity is a modifiable risk factor.
651 Supraspinal Mechanisms of Spinal Cord Stimulation for Modulation of Pain: Five Decades of Research and Prospects for the Future (Review Article)
The clinical effectiveness of spinal cord stimulation treatment of chronic intractable pain has made steady progress since the first spinal cord stimulation system was implanted in 1967, with more significant advancements in the last decade. Although early studies of spinal cord stimulation tended to focus on the peripheral and spinal segmental mechanisms of spinal cord stimulation, the study of supraspinal pathways will aid in the development of optimal stimulation paradigms for modulating neural activity in the pain signaling pathways and may help to characterize the links between pain, emotions, reward, and other higher functions in the brain. The present review examines the historical trend of clinical and preclinical studies that indicate a role for supraspinal mechanisms in spinal cord stimulation-induced pain inhibition, first in conventional spinal cord stimulation, then in newer spinal cord stimulation waveforms, and explores directions for future investigations.