A comparison of pediatric liver transplant anesthesia practices with new organ procurement and transplant network pediatric policy requirements: A report from the society for the advancement of transplant anesthesia and the society for pediatric anesthesia.

INTRODUCTION: Organ Procurement and Transplant Network (OPTN) pediatric policies on knowledge and skill requirements for key personnel failed to address the Director of Anesthesia for Pediatric Liver Transplantation. A Joint Committee representing the Society for the Advancement of Transplant Anesthesia and Society for Pediatric Anesthesia (SPA) surveyed all pediatric anesthesia liver transplant practices to determine if practices were aligned with policies and what changes would be needed for compliance. METHODS: A survey of the Director or equivalent at each program collected data about specialized knowledge and skill sets. Questions focused on (1) skill and knowledge of the Director and team, (2) requirements for appointment, (3) experience in pediatrics, and (4) characteristics of the program including the availability of pediatric resources. RESULTS: Response rate was 73% (n = 63). Most responding programs had a Director (67%) with certification, selection committee, and continuing education credits outlined in existing policies. Team members met similar requirements. Alternate pathways for acquiring knowledge and skill sets were identified between programs. CONCLUSIONS: Pediatric liver transplant anesthesiologists use knowledge and skill pathways that align with the new pediatric policies. We suggest that collaborative work with oversight agencies is needed to resolve high case volume requirements originally designed for adult programs. SUMMARY: Most pediatric liver transplant anesthesiologists in the US have specialized knowledge and skills for expert care consistent with current oversight policies. Differences in pathways to acquire knowledge and skill sets were still aligned with the new policies for pediatric transplant surgeons and bylaws for the Director of Transplant Anesthesia. We conclude that minimal changes in case volume requirements to the existing Pediatric Transplant Anesthesiology Directorship criteria that authenticates the pediatric anesthesia Director's position would improve the safety of care without limiting access to transplantation.

Intraoperative Cardiac Arrest During Adult Liver Transplantation: Incidence and Risk Factor Analysis From 7 Academic Centers in the United States.

BACKGROUND: Intraoperative cardiac arrest (ICA) has a reported frequency of 1 in 10,000 anesthetics but has a much higher estimated incidence in orthotopic liver transplantation (OLT). Single-center studies of ICA in OLT are limited by small sample size that prohibits multivariable regression analysis of risks. METHODS: Utilizing data from 7 academic medical centers, we performed a retrospective, observational study of 5296 adult liver transplant recipients (18-80 years old) between 2000 and 2017 to identify the rate of ICA, associated risk factors, and outcomes. RESULTS: ICA occurred in 196 cases (3.7% 95% confidence interval [CI], 3.2-4.2) and mortality occurred in 62 patients (1.2%). The intraoperative mortality rate was 31.6% in patients who experienced ICA. In a multivariable generalized linear mixed model, ICA was associated with body mass index (BMI) <20 (odds ratio [OR]: 2.04, 95% CI, 1.05-3.98; P = .0386), BMI ≥40 (2.16 [1.12-4.19]; P = .022), Model for End-Stage Liver Disease (MELD) score: (MELD 30-39: 1.75 [1.09-2.79], P = .02; MELD ≥40: 2.73 [1.53-4.85], P = .001), postreperfusion syndrome (PRS) (3.83 [2.75-5.34], P < .001), living donors (2.13 [1.16-3.89], P = .014), and reoperation (1.87 [1.13-3.11], P = .015). Overall 30-day and 1-year mortality were 4.18% and 11.0%, respectively. After ICA, 30-day and 1-year mortality were 43.9% and 52%, respectively, compared to 2.6% and 9.3% without ICA. CONCLUSIONS: We established a 3.7% incidence of ICA and a 1.2% incidence of intraoperative mortality in liver transplantation and confirmed previously identified risk factors for ICA including BMI, MELD score, PRS, and reoperation and identified new risk factors including living donor and length of surgery in this multicenter retrospective cohort. ICA, while rare, is associated with high intraoperative mortality, and future research must focus on therapy to reduce the incidence of ICA.

Anesthesia Management and Perioperative Infection Control in Patients With the Novel Coronavirus.

Anesthesiologists have a high risk of infection with COVID-19 during perioperative care and as first responders to airway emergencies. The potential of becoming infected can be reduced by a systematic and integrated approach that assesses infection risk. The latter leads to an acceptable choice of materials and techniques for personal protection and prevention of cross-contamination to other patients and staff. The authors have presented a protocolized approach that uses diagnostic criteria to clearly define benchmarks from the medical history along with clinical symptoms and laboratory tests. Patients can then be rapidly assigned into 1 of 3 risk categories that direct the choice of protective materials and/or techniques. Each hospital can adapt this approach to develop a system that fits its individual resources. Educating medical staff about the proper use of high-risk areas for containment serves to protect staff and patients.

Service Requirements of Liver Transplant Anesthesia Teams: Society for the Advancement of Transplant Anesthesia Recommendations.

There are disparities in liver transplant anesthesia team (LTAT) care across the United States. However, no policies address essential resources for liver transplant anesthesia services similar to other specialists. In response, the Society for the Advancement of Transplant Anesthesia appointed a task force to develop national recommendations. The Conditions of Transplant Center Participation were adapted to anesthesia team care and used to develop Delphi statements. A Delphi panel was put together by enlisting 21 experts from the fields of liver transplant anesthesiology and surgery, hepatology, critical care, and transplant nursing. Each panelist rated their agreement with and the importance of 17 statements. Strong support for the necessity and importance of 13 final items were as follows: resources, including preprocedure anesthesia assessment, advanced monitoring, immediate availability of consultants, and the presence of a documented expert in liver transplant anesthesia credentialed at the site of practice; call coverage, including schedules to assure uninterrupted coverage and methods to communicate availability; and characteristics of the team, including membership criteria, credentials at the site of practice, and identification of who supervises patient care. Unstructured comments identified competing time obligations for anesthesia and transplant services as the principle reason that the remaining recommendations to attend integrative patient selection and quality review committees were reduced to a suggestion rather than being a requirement. This has important consequences because deficits in team integration cause higher failure rates in service quality, timeliness, and efficiency. Solutions are needed that remove the time-related financial constraints of competing service requirements for anesthesiologists. In conclusion, using a modified Delphi technique, 13 recommendations for the structure of LTATs were agreed upon by a multidisciplinary group of experts.

Anesthetic management of lung transplantation: Results from a multicenter, cross-sectional survey by the society for advancement of transplant anesthesia.

BACKGROUND: Current protocols for the perioperative care of lung transplant (LTX) recipients lack rigorous evidence and are often empiric, based upon institutional preferences. We surveyed LTX anesthesiologists to determine the most common practices. METHODS: We developed a survey of 40 questions regarding perioperative care of LTX recipients using Qualtrics software. The survey was sent out to members of the Society of Cardiovascular Anesthesiologists performing LTX at geographically diverse sites to facilitate data collection for as many practices as possible. RESULTS: The responses were center-weighed (127 responses, 85% from academic settings). The clamshell approach was commonly used (70%). Cardiopulmonary bypass was preferred by 56%, ex vivo lung perfusion utilized by 43%, and 49.4% indicated they use lungs from donation after circulatory determination of death. Most (69%) used oximetric pulmonary artery catheters, 60% used tissue oximetry, and 89.3% utilized transesophageal echocardiography. Inhaled nitric oxide was preferred by 48%, restrictive fluid management by 48%, and systemic analgesia advocated by 49% of participants. Inspired oxygen concentration <30% was applied to the new lung on reperfusion by 28% of the respondents. CONCLUSION: Variations in healthcare delivery and utilization for LTX recipients indicate gaps in knowledge and potential opportunities to improve the quality of care.

The association of allogeneic blood transfusion and the recurrence of hepatic cancer after surgical resection.

There is conflicting evidence whether allogeneic blood transfusion influences survival or cancer recurrence after resection of hepatocellular cancer. We followed up 1469 patients who had undergone hepatocellular resection for a median (IQR [range]) of 45 (21-78 [0-162]) months, of whom 626 (43%) had had blood transfusion within 7 days of surgery. Both disease-free survival and patient survival were measured using a proportional hazards regression model and inverse probability of treatment weighting. We used restricted cubic splines for the association of the number of packed red blood cell units transfused with cancer recurrence and survival. We found that peri-operative blood transfusion was independently associated with survival and cancer recurrence after resection of hepatocellular carcinoma. Adjusted hazard ratios (95%CI) for the association of blood transfusion with cancer recurrence and all-cause mortality were 1.3 (1.1-1.4) and 1.9 (1.6-2.3), p < 0.001 for both. With more units transfused cancer recurrence was more likely and survival was shorter. The association of the number of transfused units was non-linear for cancer recurrence and linear response for all-cause mortality.

Adaptation of non-linear mixed amount with zero amount response surface model for analysis of concentration-dependent synergism and safety with midazolam, alfentanil, and propofol sedation.

BACKGROUND: The non-linear mixed amount with zero amounts response surface model can be used to describe drug interactions and predict loss of response to noxious stimuli and respiratory depression. We aimed to determine whether this response surface model could be used to model sedation with the triple drug combination of midazolam, alfentanil and propofol. METHODS: Sedation was monitored in 56 patients undergoing gastrointestinal endoscopy (modelling group) using modified alertness/sedation scores. A total of 227 combinations of effect-site concentrations were derived from pharmacokinetic models. Accuracy and the area under the receiver operating characteristic curve were calculated. Accuracy was defined as an absolute difference <0.5 between the binary patient responses and the predicted probability of loss of responsiveness. Validation was performed with a separate group (validation group) of 47 patients. RESULTS: Effect-site concentration ranged from 0 to 108 ng ml-1 for midazolam, 0-156 ng ml-1 for alfentanil, and 0-2.6 µg ml-1 for propofol in both groups. Synergy was strongest with midazolam and alfentanil (24.3% decrease in U50, concentration for half maximal drug effect). Adding propofol, a third drug, offered little additional synergy (25.8% decrease in U50). Two patients (3%) experienced respiratory depression. Model accuracy was 83% and 76%, area under the curve was 0.87 and 0.80 for the modelling and validation group, respectively. CONCLUSION: The non-linear mixed amount with zero amounts triple interaction response surface model predicts patient sedation responses during endoscopy with combinations of midazolam, alfentanil, or propofol that fall within clinical use. Our model also suggests a safety margin of alfentanil fraction <0.12 that avoids respiratory depression after loss of responsiveness.

Social and Financial Outcomes of Living Liver Donation: A Prospective Investigation Within the Adult-to-Adult Living Donor Liver Transplantation Cohort Study 2 (A2ALL-2).

Because results from single-center (mostly kidney) donor studies demonstrate interpersonal relationship and financial strains for some donors, we conducted a liver donor study involving nine centers within the Adult-to-Adult Living Donor Liver Transplantation Cohort Study 2 (A2ALL-2) consortium. Among other initiatives, A2ALL-2 examined the nature of these outcomes following donation. Using validated measures, donors were prospectively surveyed before donation and at 3, 6, 12, and 24 mo after donation. Repeated-measures regression models were used to examine social relationship and financial outcomes over time and to identify relevant predictors. Of 297 eligible donors, 271 (91%) consented and were interviewed at least once. Relationship changes were positive overall across postdonation time points, with nearly one-third reporting improved donor family and spousal or partner relationships and >50% reporting improved recipient relationships. The majority of donors, however, reported cumulative out-of-pocket medical and nonmedical expenses, which were judged burdensome by 44% of donors. Lower income predicted burdensome donation costs. Those who anticipated financial concerns and who held nonprofessional positions before donation were more likely to experience adverse financial outcomes. These data support the need for initiatives to reduce financial burden.

Predicting the Best Fit: A Comparison of Response Surface Models for Midazolam and Alfentanil Sedation in Procedures With Varying Stimulation.

BACKGROUND: Selecting an effective dose of sedative drugs in combined upper and lower gastrointestinal endoscopy is complicated by varying degrees of pain stimulation. We tested the ability of 5 response surface models to predict depth of sedation after administration of midazolam and alfentanil in this complex model. The procedure was divided into 3 phases: esophagogastroduodenoscopy (EGD), colonoscopy, and the time interval between the 2 (intersession). METHODS: The depth of sedation in 33 adult patients was monitored by Observer Assessment of Alertness/Scores. A total of 218 combinations of midazolam and alfentanil effect-site concentrations derived from pharmacokinetic models were used to test 5 response surface models in each of the 3 phases of endoscopy. Model fit was evaluated with objective function value, corrected Akaike Information Criterion (AICc), and Spearman ranked correlation. A model was arbitrarily defined as accurate if the predicted probability is <0.5 from the observed response. RESULTS: The effect-site concentrations tested ranged from 1 to 76 ng/mL and from 5 to 80 ng/mL for midazolam and alfentanil, respectively. Midazolam and alfentanil had synergistic effects in colonoscopy and EGD, but additivity was observed in the intersession group. Adequate prediction rates were 84% to 85% in the intersession group, 84% to 88% during colonoscopy, and 82% to 87% during EGD. The reduced Greco and Fixed alfentanil concentration required for 50% of the patients to achieve targeted response Hierarchy models performed better with comparable predictive strength. The reduced Greco model had the lowest AICc with strong correlation in all 3 phases of endoscopy. Dynamic, rather than fixed, γ and γalf in the Hierarchy model improved model fit. CONCLUSIONS: The reduced Greco model had the lowest objective function value and AICc and thus the best fit. This model was reliable with acceptable predictive ability based on adequate clinical correlation. We suggest that this model has practical clinical value for patients undergoing procedures with varying degrees of stimulation.

Director of anesthesiology for liver transplantation: existing practices and recommendations by the United Network for Organ Sharing.

A new Organ Procurement and Transplantation Network/United Network for Organ Sharing bylaw recommends that all centers appoint a director of liver transplant anesthesia with a uniform set of criteria. We obtained survey data from the Liver Transplant Anesthesia Consortium so that we could compare existing criteria for a director in the United States with the current recommendations. The data set included responses from adult academic liver transplant programs before the new bylaw. The respondent rates were within statistical limits to exclude sampling bias. All centers had a director of liver transplant anesthesia. The criteria varied between institutions, and the data suggest that the availability of resources influenced the choice of criteria. The information suggests that the criteria used in the new bylaw reflect existing practices. The bylaw plays an important role in supporting emerging leadership roles in liver transplant anesthesia and brings greater uniformity to the directorship position.

Increase of beta-amyloid and C-reactive protein in liver transplant recipients with postoperative cognitive dysfunction.

BACKGROUND: Postoperative cognitive dysfunction (POCD) is an adverse condition characterized by declined cognitive functions following surgeries and anesthesia. POCD has been associated with increased hospital stay and mortality. There are histological similarities to Alzheimer's disease. Most early studies were conducted in patients receiving cardiac surgery. Since there is no information about POCD in liver transplant recipients, we measured the incidence of POCD in patients after liver transplantation and examined the correlation between neurological dysfunction and biological markers of dementia-based diseases. METHODS: We studied 25 patients who had a liver transplan-tation between July 2008 and February 2009. Patients with prior encephalopathy or risk factors associated with the development of POCD were excluded from the study. Five validated neuropsychiatric tests were used for diagnosis. The diagnosis was based on one standard deviation decline in two of the five neuropsychiatric tests. The correlation between patient variables and the development of POCD was examined. Serum levels of beta-amyloid and C-reactive protein were measured by standard ELISA and compared between patients with and without POCD. RESULTS: POCD was present in 11 (44%) of the 25 patients. Patients with POCD had significantly higher MELD scores, were more often Child-Pugh class C and received more blood transfusion during surgery. The serum beta-amyloid protein and C-reactive protein concentrations were significantly increased at 24 hours after surgery in the POCD group. CONCLUSIONS: The incidence of POCD in our group of liver transplant patients was greater than that reported in other surgical patients. The increase in the serum biomarkers of dementia in the POCD patients supports the hypothesis that chronic cognitive defects are due to a process similar to that seen in Alzheimer's disease.

Anesthesia for liver transplantation in US academic centers: institutional structure and perioperative care.

Investigators at a single institution have shown that the organization of the anesthesia team influences patient outcomes after liver transplant surgery. Little is known about how liver transplant anesthesiologists are organized to deliver care throughout the United States. Therefore, we collected quantitative survey data from adult liver transplant programs in good standing with national governing agencies so that we could describe team structure and duties. Information was collected from 2 surveys in a series of quantitative surveys conducted by the Liver Transplant Anesthesia Consortium. All data related to duties, criteria for team membership, interactions/communication with the multidisciplinary team, and service availability were collected and summarized. Thirty-four of 119 registered transplant centers were excluded (21 pediatric centers and 13 centers not certified by national governing agencies). Private practice sites (26) were later excluded because of a poor response rate. There were minimal changes in the compositions of the programs between the 2 surveys. All academic programs had distinct liver transplant anesthesia teams. Most had set criteria for membership and protocols outlining the preoperative evaluation, attended selection committees, and were always available for transplant surgery. Fewer were involved in postoperative care or were available for patients needing subsequent surgery. Most trends were associated with the center volume. In conclusion, some of the variance in team structure and responsibilities is probably related to resources available at the site of practice. However, similarities in specific duties across all teams suggest some degree of self-initiated specialization.

Use of higher thromboelastogram transfusion values is not associated with greater blood loss in liver transplant surgery.

Plasma-containing products are given during the pre-anhepatic stage of liver transplant surgery to correct abnormal thromboelastogram (TEG) values and prevent blood loss due to coagulation defects. However, evidence suggests that abnormal TEG results do not always predict bleeding. We questioned what effect using higher TEG values to initiate treatment would have on blood loss. A single transfusion protocol was used for all patients who underwent liver transplantation between 2007 and 2010. Thirty-eight patients received coagulation products when standard TEG cutoff values were exceeded, whereas another 39 patients received coagulation products when the TEG values were 35% greater than normal. The results of postoperative coagulation tests for total blood loss and the use of blood products were compared for the 2 groups. When the critical TEG values for transfusion were higher, significantly fewer units of fresh frozen plasma (5.58 ± 6.49 versus 11.53 ± 6.66 U) and pheresis platelets (1.84 ± 1.33 versus 3.55 ± 1.43 U) were used. There were no differences in blood loss or postoperative blood product use. In conclusion, the use of higher critical TEG values to initiate the transfusion of plasma-containing products is not associated with increased blood loss. Further testing is necessary to identify what TEG value predicts bleeding due to a deficit in coagulation factors.

Discriminant analysis for anaesthetic decision-making: an intelligent recognition system for epidural needle insertion.

BACKGROUND: Incorrect placement of epidural catheters causes medical complications. We used linear discriminant analysis (LDA) to develop an intelligent recognition system (i-RS) in order to guide epidural placement and reduce physician error. METHODS: We analysed real-time dual-wavelength fibreoptic data recorded from the end of an epidural needle in a live porcine model. Two categories of tissue layers were necessary for correct placement of catheter: epidural space and ligamentum flavum. The data were tested using linear, quadratic and logistic parametric analysis to identify which method could distinguish the two anatomical structures. RESULTS: LDA was the best fit for our model. There was ∼80% sensitivity and specificity for correct anatomical identification. Error rates based on cross-validation were 17.0% for the epidural space and 18.6% for ligamentum flavum. Error rates were greater with the 532 nm compared with 650 nm wavelength. CONCLUSIONS: The sensitivity and specificity of LDA for identifying the correct anatomical structure was similar to a physician who is an expert in epidural placement. Overall performance of an i-RS could be improved by expanding the database for decision-making and adding a category of uncertainty. This would reduce complications caused by incorrect epidural placement.

Recommendations From the Society for the Advancement of Transplant Anesthesiology Fellowship Committee: Core Competencies and Milestones for the Kidney/Pancreas Component of Abdominal Organ Transplant Anesthesia Fellowship.

The Society for the Advancement of Transplant Anesthesia (SATA) is dedicated to improving patient care in all facets of transplant anesthesia. The anesthesia fellowship training recommendations for thoracic transplantation (heart and lungs) and part of the abdominal organ transplantation (liver) have been presented in previous publications. The SATA Fellowship Committee has completed the remaining component of abdominal transplant anesthesia (kidney/pancreas) and has assembled core competencies and milestones derived from expert consensus to guide the education and overall preparation of trainees providing care for kidney/pancreas transplant recipients. These recommendations provide a comprehensive approach to pre-operative evaluation, vascular access procedures, advanced hemodynamic monitoring, assessment of coagulation and metabolic abnormalities, operative techniques, and post-operative pain control. As such, this document supplements the current liver/hepatic transplant anesthesia fellowship training programs to include all aspects of "Abdominal Organ Transplant Anesthesia" recommended knowledge.

Eyes in the needle: novel epidural needle with embedded high-frequency ultrasound transducer--epidural access in porcine model.

BACKGROUND: Epidural needle insertion is usually a blind technique where the rate of adverse events depends on the experience of the operator. A novel ultrasound method to guide epidural catheter insertion is described. METHODS: An ultrasound transducer (40 MHz, a -6 dB fractional bandwidth of 50%) was placed into the hollow chamber of an 18-gauge Tuohy needle. The single crystal was polished to a thickness of 50 µm, with a width of 0.5 mm. Tissue planes were identified from the reflected signals in an A-mode display. The device was inserted three times into both the lumbar and thoracic regions of five pigs (average weight, 20 kg) using a paramedian approach at an angle of 35-40°. The epidural space was identified using signals from the ligamentum flavum and dura mater. Epidural catheters were placed with each attempt and placement confirmed by contrast injection. RESULTS: The ligamentum flavum was identified in 83.3% of insertions and the dura mater in all insertions. The dura mater signal was stronger than that of the ligamentum flavum and served as a landmark in all epidural catheter insertions. Contrast studies confirmed correct placement of the catheter in the epidural space of all study animals. CONCLUSIONS: This is the first study to introduce a new ultrasound probe embedded in a standard epidural needle. It is anticipated that this technique could reduce failed epidural blocks and complications caused by dural puncture.

When Is a Critically Ill Cirrhotic Patient Too Sick to Transplant? Development of Consensus Criteria by a Multidisciplinary Panel of 35 International Experts.

BACKGROUND: Critically ill cirrhotic patients are increasingly transplanted, but there is no consensus about futile liver transplantation (LT). Therefore, the decision to delay or deny LT is often extensively debated. These debates arise from different opinions of futility among transplant team members. This study aims to achieve a multinational and multidisciplinary consensus on the definition of futility in LT and to develop well-articulated criteria for not proceeding with LT due to futility. METHODS: Thirty-five international experts from anesthesiology/intensive care, hepatology, and transplant surgery were surveyed using the Delphi method. More than 70% of similar answers to a question were necessary to define agreement. RESULTS: The panel recommended patient and graft survival at 1 year after LT to define futility. Severe frailty and persistent fever or <72 hours of appropriate antimicrobial therapy in case of ongoing sepsis were considered reasons to delay LT. A simple assessment of the number of organs failing was considered the most appropriate way to decide whether LT should be delayed or denied, with respiratory, circulatory and metabolic failures having the most influence in this decision. The thresholds of severity of organ failures contraindicating LT for which a consensus was achieved were a Pao2/FiO2 ratio<150 mm Hg, a norepinephrine dose >1 µg/kg per minute and a serum lactate level >9 mmol/L. CONCLUSIONS: Our expert panel provides a consensus on the definition of futile LT and on specific criteria for postponing or denying LT. A framework that may facilitate the decision if a patient is too sick for transplant is presented.

A new technique to assist epidural needle placement: fiberoptic-guided insertion using two wavelengths.

BACKGROUND: Up to 10% of epidurals fail due to incorrect catheter placement. We describe a novel optical method to assist epidural catheter insertion in a porcine model. METHODS: Optical emissions were tested on ex vivo tissues from porcine paravertebral tissues to identify optical reflective spectra. The wavelengths of 650 and 532 nm differentiated epidural space from the ligamentum flavum. We then used a hollow stylet that contained optical fibers to place epidural needles in anesthetized pigs. Real-time data were displayed on an oscilloscope and stored for analysis. A total of 50 punctures were done in four laboratory pigs. Data were expressed as mean +/- SD. RESULTS: Paired t test shows significant optical differences between the epidural space and the ligamentum flavum at both 650 nm (P < 0.001) and 532 nm (P = 0.014). Mean magnitudes for 650 nm, 532 nm, and their ratio were 3.565 +/- 0.194, 2.542 +/- 0.145, and 0.958 +/- 0.172 at epidural space and 3.842 +/- 0.191, 2.563 +/- 0.131, and 1.228 +/- 0.244 at ligamentum flavum, respectively. There were no differences in the optical characteristics of the ligamentum flavum and epidural space at different levels in the lumbar and thoracic region (two-way ANOVA P > 0.05). CONCLUSIONS: This is the first study to introduce a new optical method to localize epidural space in a porcine model. Epidural space could be identified by the changes in the reflective pattern of light emitted at 650 nm, which were specific for the ligamentum flavum and dural tissue. Real-time optical information successfully guided a modified Tuohy needle into the epidural space.