Can pain under anesthesia be measured? Pain-related brain function using functional near-infrared spectroscopy during knee surgery.

Significance: Quantitative measurement of perisurgical brain function may provide insights into the processes contributing to acute and chronic postsurgical pain. Aim: We evaluate the hemodynamic changes in the prefrontal cortex (medial frontopolar cortex/mFPC and lateral prefrontal cortex) and the primary somatosensory cortex/S1 using functional near-infrared spectroscopy (fNIRS) in 18 patients (18.2±3.3 years, 11 females) undergoing knee arthroscopy. Approach: We examined the (a) hemodynamic response to surgery and (b) the relationship between surgery-modulated cortical connectivity (using beta-series correlation) and acute postoperative pain levels using Pearson's r correlation with 10,000 permutations. Results: We show a functional dissociation between mFPC and S1 in response to surgery, where mFPC deactivates, and S1 activates following a procedure. Furthermore, the connectivity between (a) left mFPC and right S1 (original r=-0.683, ppermutation=0.001), (b) right mFPC and right S1 (original r=-0.633, ppermutation=0.002), and (c) left mFPC and right S1 (original r=-0.695, ppermutation=0.0002) during surgery were negatively associated with acute postoperative pain levels. Conclusions: Our findings suggest that greater functional dissociation between mFPC and S1 is likely the result of inadequately controlled nociceptive barrage during surgery leading to more significant postoperative pain. It also supports the utility of fNIRS during the perioperative state for pain monitoring and patient risk assessment for chronic pain.

fNIRS brain measures of ongoing nociception during surgical incisions under anesthesia.

Significance: Functional near-infrared spectroscopy (fNIRS) has evaluated pain in awake and anesthetized states. Aim: We evaluated fNIRS signals under general anesthesia in patients undergoing knee surgery for anterior cruciate ligament repair. Approach: Patients were split into groups: those with regional nerve block (NB) and those without (non-NB). Continuous fNIRS measures came from three regions: the primary somatosensory cortex (S1), known to be involved in evaluation of nociception, the lateral prefrontal cortex (BA9), and the polar frontal cortex (BA10), both involved in higher cortical functions (such as cognition and emotion). Results: Our results show three significant differences in fNIRS signals to incision procedures between groups: (1) NB compared with non-NB was associated with a greater net positive hemodynamic response to pain procedures in S1; (2) dynamic correlation between the prefrontal cortex (PreFC) and S1 within 1 min of painful procedures are anticorrelated in NB while positively correlated in non-NB; and (3) hemodynamic measures of activation were similar at two separate time points during surgery (i.e., first and last incisions) in PreFC and S1 but showed significant differences in their overlap. Comparing pain levels immediately after surgery and during discharge from postoperative care revealed no significant differences in the pain levels between NB and non-NB. Conclusion: Our data suggest multiple pain events that occur during surgery using devised algorithms could potentially give a measure of "pain load." This may allow for evaluation of central sensitization (i.e., a heightened state of the nervous system where noxious and non-noxious stimuli is perceived as painful) to postoperative pain levels and the resulting analgesic consumption. This evaluation could potentially predict postsurgical chronic neuropathic pain.

Rhythmic Change of Cortical Hemodynamic Signals Associated with Ongoing Nociception in Awake and Anesthetized Individuals: An Exploratory Functional Near Infrared Spectroscopy Study.

BACKGROUND: Patients undergoing surgical procedures are vulnerable to repetitive evoked or ongoing nociceptive barrage. Using functional near infrared spectroscopy, the authors aimed to evaluate the cortical hemodynamic signal power changes during ongoing nociception in healthy awake volunteers and in surgical patients under general anesthesia. The authors hypothesized that ongoing nociception to heat or surgical trauma would induce reductions in the power of cortical low-frequency hemodynamic oscillations in a similar manner as previously reported using functional magnetic resonance imaging for ongoing pain. METHODS: Cortical hemodynamic signals during noxious stimuli from the fontopolar cortex were evaluated in two groups: group 1, a healthy/conscious group (n = 15, all males) where ongoing noxious and innocuous heat stimulus was induced by a contact thermode to the dorsum of left hand; and group 2, a patient/unconscious group (n = 13, 3 males) receiving general anesthesia undergoing knee surgery. The fractional power of low-frequency hemodynamic signals was compared across stimulation conditions in the healthy awake group, and between patients who received standard anesthesia and those who received standard anesthesia with additional regional nerve block. RESULTS: A reduction of the total fractional power in both groups-specifically, a decrease in the slow-5 frequency band (0.01 to 0.027 Hz) of oxygenated hemoglobin concentration changes over the frontopolar cortex-was observed during ongoing noxious stimuli in the healthy awake group (paired t test, P = 0.017; effect size, 0.70), and during invasive procedures in the surgery group (paired t test, P = 0.003; effect size, 2.16). The reduction was partially reversed in patients who received a regional nerve block that likely diminished afferent nociceptive activity (two-sample t test, P = 0.002; effect size, 2.34). CONCLUSIONS: These results suggest common power changes in slow-wave cortical hemodynamic oscillations during ongoing nociceptive processing in conscious and unconscious states. The observed signal may potentially promote future development of a surrogate signal to assess ongoing nociception under general anesthesia.

A Dedicated Satellite Trauma Orthopaedic Program Operating Room Safely Increases Capacity.

BACKGROUND: Providing high-value care for urgent orthopaedic trauma patients requires effective and timely treatment. Herein, we describe the implementation of an innovative program utilizing the operating room (OR) capacity of a satellite campus to decrease stress on a pediatric tertiary care center without jeopardizing patient safety. METHODS: In addition to the daily emergency surgical room on the main campus, a dedicated orthopaedic trauma surgery OR was established in a satellite hospital location for 3 days per week in the summer and for 2 days per week for the rest of the year. Nonemergency, non-multitrauma operative fracture cases presenting to our tertiary care facility emergency department or orthopaedic clinic were considered for satellite referral. Eligible patients required clearance for transfer via orthopaedic, emergency department, and anesthesia checklists. An opt-out policy was established for provider judgment or patient family concern to overrule transfer decisions. Selected patients were discharged home with satellite OR scheduling or approved for same-day satellite location admission. Short elective cases were performed when openings existed in the schedule. RESULTS: From June 1, 2016, through June 30, 2017, 480 cases (372 trauma, 108 elective) were completed in our satellite OR. The most common trauma cases that were treated in the satellite OR were type-II supracondylar humeral fractures (n = 76). Summer months averaged 41.75 trauma cases and 11.25 elective cases per month, with 3.15 trauma cases and 0.85 elective cases per day. Nonsummer months averaged 22.78 trauma cases and 7.00 elective cases per month, with 2.93 trauma and 0.90 elective cases per day. Of the 17 postoperative issues, the greatest number (n = 7 [41%]) involved symptomatic hardware. The remaining complications were not surgeon or geographic-site-specific. There were no intraoperative complications, compartment syndrome episodes, or patients who required transfer back to our tertiary care facility for unexpected or serious medical issues. CONCLUSIONS: With the proper screening protocols in place for appropriate patient selection, the use of a dedicated satellite orthopaedic trauma OR can increase capacity without compromising patient safety.

Technical challenges of atrial septal stent placement in fetuses with hypoplastic left heart syndrome and intact atrial septum.

OBJECTIVES: The objective of this study was to describe our single-institution experience with prenatal atrial septal stent placement for fetuses with hypoplastic left heart syndrome and an intact atrial septum (HLHS/IAS). BACKGROUND: Infants born with HLHS/IAS are at high risk for neonatal death, despite maximal postnatal therapy. Prenatal atrial septoplasty by static balloon dilation has been effective in decompressing the left atrium (LA) in utero, but several factors have limited the size of septal defects. We attempted to overcome the limitations of balloon septoplasty using transcatheter atrial septal stents. METHODS: All records from our institution of fetuses with HLHS/IAS that underwent prenatal atrial septal stent placement were reviewed, including operative notes and echocardiograms. RESULTS: Nine fetuses between 24 and 31 weeks gestation with HLHS/IAS underwent attempted fetal atrial septal stent placement. A stent was deployed across the atrial septum in five fetuses, with four fetuses demonstrating flow across the stent at the time of intervention. In four cases, stent placement failed due to malposition or embolization, but in three of the four cases, atrial balloon septoplasty at the same in-utero procedure successfully and acutely decompressed the LA. There were no maternal complications. There was one fetal demise. The remaining eight fetuses survived to delivery, but four died in the neonatal period (two of which had been stented). CONCLUSIONS: Ultrasound-guided atrial septal stent placement is feasible in some fetuses with HLHS/IAS. Visualization of the septum and catheter tip is critical to technical success. Additional experience is necessary to determine the clinical impact of this intervention. © 2013 Wiley Periodicals, Inc.

Fetal anesthesia and pain management for intrauterine therapy.

Anesthesia provision for fetal intervention differs from most other anesthetic situations insofar as anesthesiologists must care for 2 or more patients-each with potentially conflicting requirements. The first is the mother who can readily indicate discomforts, can be monitored directly, and to whom drugs may be administered directly and easily. For the fetus (or fetuses), nociception must be assumed or inferred indirectly, monitoring is limited at best, and drug administration is complicated and often indirect. Fetal and maternal hemodynamic stability must be assured; and a plan to resuscitate the fetus, should problems occur during the procedure, must be developed.

Acute intraoperative neurogenic pulmonary edema during endoscopic ventriculoperitoneal shunt revision.

We present an incident of fulminant intraoperative neurogenic pulmonary edema in a 21-yr-old man undergoing an endoscopic ventriculoperitoneal shunt revision. His intraoperative course was complicated by intracranial bleeding requiring vigorous saline irrigation, which was accompanied by an acute increase in heart rate and arterial blood pressure. Shortly thereafter, the patient developed pulmonary edema and was promptly treated with resolution of pulmonary symptoms within 24 h. This report addresses the importance of recognition of neurogenic pulmonary edema as a possible intraoperative complication resulting from an increase in intracranial pressure due to hemorrhage and intraventricular irrigation during endoscopic ventriculoperitoneal shunt revision.

Predictors of technical success and postnatal biventricular outcome after in utero aortic valvuloplasty for aortic stenosis with evolving hypoplastic left heart syndrome.

BACKGROUND: Aortic stenosis in the midgestation fetus with a normal-sized or dilated left ventricle predictably progresses to hypoplastic left heart syndrome when associated with certain physiological findings. Prenatal balloon aortic valvuloplasty may improve left heart growth and function, possibly preventing evolution to hypoplastic left heart syndrome. METHODS AND RESULTS: Between March 2000 and October 2008, 70 fetuses underwent attempted aortic valvuloplasty for critical aortic stenosis with evolving hypoplastic left heart syndrome. We analyzed this experience to determine factors associated with procedural and postnatal outcome. The median gestational age at intervention was 23 weeks. The procedure was technically successful in 52 fetuses (74%). Relative to 21 untreated comparison fetuses, subsequent prenatal growth of the aortic and mitral valves, but not the left ventricle, was improved after intervention. Nine pregnancies (13%) did not reach a viable term or preterm birth. Seventeen patients had a biventricular circulation postnatally, 15 from birth. Larger left heart structures and higher left ventricular pressure at the time of intervention were associated with biventricular outcome. A multivariable threshold scoring system was able to discriminate fetuses with a biventricular outcome with 100% sensitivity and modest positive predictive value. CONCLUSIONS: Technically successful aortic valvuloplasty alters left heart valvar growth in fetuses with aortic stenosis and evolving hypoplastic left heart syndrome and, in a subset of cases, appeared to contribute to a biventricular outcome after birth. Fetal aortic valvuloplasty carries a risk of fetal demise. Fetuses undergoing in utero aortic valvuloplasty with an unfavorable multivariable threshold score at the time of intervention are very unlikely to achieve a biventricular circulation postnatally.

Pathophysiology, management, and outcomes of fetal hemodynamic instability during prenatal cardiac intervention.

Prenatal cardiac intervention (PCI) may favorably alter the in utero course of some congenital heart defects. In our preliminary experience with PCI, fetal hemodynamic instability (FHI) characterized by bradycardia and ventricular dysfunction was common. This study evaluated the pathophysiology, management, and short-term outcomes of FHI during PCI for aortic stenosis with evolving hypoplastic left heart syndrome (HLHS), HLHS with restrictive atrial septum, pulmonary atresia with intact ventricular septum, and hydrops due to structural heart disease. From 2000 to 2006, 83 fetuses underwent PCI, with ventricular access in 63, atrial access in 17, and both in three. FHI occurred in 37 fetuses (45%). FHI was associated with transventricular PCI (all but one case of FHI; p < 0.001) and large hemopericardium (n=9; p=0.07). Prolonged FHI was associated with severe ventricular distortion during ventricular puncture (p = 0.06). FHI was treated with resuscitation medications in 31 of 37 fetuses and resolved in all 37. Five fetuses died within 1 d of PCI: four had FHI and one had a massive hemopericardium. FHI is common and clinically important during transventricular PCI and may be caused by a ventricular reflex or reduced cardiac output from cardiac distortion during ventricular puncture. Hemopericardium may be causative in a subset of fetuses.

Maternal mirror syndrome after in utero aortic valve dilation. A case report.

Fetal hydrops of various etiologies can be associated with maternal mirror syndrome. The exact pathophysiology of this rare disorder remains unclear, yet it can result in significant maternal and fetal morbidity. The recent advances in prenatal diagnosis and therapeutic interventions have focused on altering the course of pathologies associated with an expected poor prognosis. Severe fetal aortic valve stenosis with its potential for hypoplastic left heart fit this category. We report a case of maternal mirror syndrome in a parturient following intrauterine therapy for severe fetal aortic stenosis and hydrops. Despite a technically successful intervention, the mother required emergency cesarean section. We review the few reports of mirror syndrome as well as the current approaches to fetal aortic stenosis. This case reinforces the need for in depth risk analysis prior to fetal interventions. It also emphasizes the advantage of earlier detection and therapy with fetal aortic stenosis since fetal hydrops carries a somber prognosis.