- Liver Transplant Anesthesiology
- Perioperative Point of Care Ultrasound
Clinical Associate Professor, Anesthesiology, Perioperative and Pain Medicine
Associate Division Chief, Multispecialty Division, Department of Anesthesiology, Perioperative and Pain Medicine (2022 - 2023)
Residency Program Director, Department of Anesthesiology, Perioperative and Pain Medicine (2023 - Present)
Clerkship Director, Medical Student General Operating Room Anesthesiology Rotation (2015 - 2019)
Associate Program Director, Stanford Medicine Anesthesiology/Internal Medicine Combined Residency Program (2019 - 2023)
Fellowship: Stanford University Critical Care Medicine Fellowship (2014) CA
Residency: Stanford University Anesthesiology Residency (2013) CA
Internship: Santa Clara Valley Medical Center (2010) CA
Medical Education: Boston University School of Medicine (2009) MA
Board Certification: American Board of Anesthesiology, Anesthesiology (2014)
Board Certification: American Board of Anesthesiology, Critical Care Medicine (2014)
EEG response of dexmedetomidine during drug induced sleep endoscopy.
Frontiers in neuroscience
2023; 17: 1144141
Introduction: Dexmedetomidine is one of the anesthetics of choice for drug induced sleep endoscopy (DISE), with advantages including limited respiratory depression, analgesia, and decreased incidence of emergence delirium. However, challenges with determining sedation levels and prolonged recovery have limited its usage. An improved understanding of the effect of dexmedetomidine on the level of sedation and the corresponding electroencephalographic (EEG) changes could help overcome these barriers.Methods: Fifty-one patients received dexmedetomidine sedation with Richmond Agitation-Sedation Scale (RASS) score assessment and continuous EEG monitoring via SedLine for DISE. We constructed a pharmacokinetic model to determine continuous dexmedetomidine blood concentration. From the SedLine, we extracted the patient state index (PSI), and from the EEG we calculated the spectral edge frequency 95% (SEF95) and the correlation dimension (CD), a type of fractal dimension used to assess the complexity of a system. These metrics were subsequently compared against one another and with the dexmedetomidine concentration.Results: Our pharmacokinetic model yielded a two-compartment model with volumes of 51.8L and 106.2L, with clearances of 69.5 and 168.9L/h, respectively, and a time to effect of 9min, similar to prior studies. Based on this model, decreasing RASS score, SEF95, CD, and PSI were all significantly associated with increasing dexmedetomidine concentration (p<0.001, p=0.006, p<0.001 respectively). The CD, SEF95, and PSI better captured the effects of increasing dexmedetomidine concentration as compared to the RASS score. Simulating dexmedetomidine concentration based on titration to target levels derived from CD and PSI confirmed commonly used dexmedetomidine infusion dosages.Conclusion: Dexmedetomidine use for DISE confirmed previous pharmacokinetic models seen with dexmedetomidine. Complex EEG metrics such as PSI and CD, as compared to RASS score and SEF95, better captured changes in brain state from dexmedetomidine and have potential to improve the monitoring of dexmedetomidine sedation.
View details for DOI 10.3389/fnins.2023.1144141
View details for PubMedID 37521700
Evaluation of patient state index, bispectral index, and entropy during drug induced sleep endoscopy with dexmedetomidine.
Journal of clinical monitoring and computing
Multiple electroencephalographic (EEG) monitors and their associated EEG markers have been developed to aid in assessing the level of sedation in the operating room. While many studies have assessed the response of these markers to propofol sedation and anesthetic gases, few studies have compared these markers when using dexmedetomidine, an alpha-2 agonist. Fifty-one patients underwent drug induced sleep endoscopy with dexmedetomidine sedation. Continuous EEG was captured using SedLine (Masimo, Inc), and a playback system was used to extract the bispectral index (BIS) (Medtronic Inc), the patient state index (PSI) (Masimo, Inc), the state and response Entropy (GE Healthcare), and calculate the spectral edge frequency 95% (SEF95). Richmond Agitation-Sedation Scale (RASS) scores were assessed continually throughout the procedure and in recovery. We assessed the correlation between EEG markers and constructed ordinal logistic regression models to predict the RASS score and compare EEG markers. All three commercial EEG metrics were significantly associated with the RASS score (p<0.001 for all metrics) whereas SEF95 alone was insufficient at characterizing dexmedetomidine sedation. PSI and Entropy achieved higher accuracy at predicing deeper levels of sedation as compared to BIS (PSI: 58.3%, Entropy: 58.3%, BIS: 44.4%). Lightening secondary to RASS score assessment is significantly captured by all three commercial EEG metrics (p<0.001). Commercial EEG monitors can capture changes in the brain state associated with the RASS score during dexmedetomidine sedation. PSI and Entropy were highly correlated and may be better suited for assessing deeper levels of sedation.
View details for DOI 10.1007/s10877-022-00952-9
View details for PubMedID 36550344
Evaluation of the Stanford Anesthesiology Faculty Teaching Scholars Program Using the Context, Input, Process, and Product Framework.
The journal of education in perioperative medicine : JEPM
2022; 24 (4): E693
Background: Faculty development programs are essential to the educational mission of academic medical centers as they promote skill development and career advancement and should be regularly evaluated to determine opportunities for improvement. The context, input, process, and product (CIPP) framework evaluates all phases of a program and focuses on improvement and outcomes. The aim of this study was to use the CIPP framework to evaluate the Stanford Anesthesiology Faculty Teaching Scholars Program.Methods: Using the CIPP framework, a survey was developed for alumni (2007 to 2018) of the program, followed by structured interviews, and each interview was deductively coded to identify themes.Results: Twenty-six of the 54 (48% response rate) participants in the program completed the survey, with 23 completing their projects and 17 of those projects still part of the anesthesiology training program. Seventeen survey responders went on to educational leadership roles. Twenty-five of the 26 survey responders would recommend this program to their colleagues. Fifteen structured interviews were conducted. Using the CIPP framework, themes were identified for context (reason for participation, previous experience in medical education, and resident education impact), input (benefits/negatives of the lecture series, availability of resources, and adequacy of nonclinical time), process (resident participation, mentorship, and barriers to implementation), and product (project completion, education sustainability, positive/negative outcomes of the program, and suggestions for improvement).Conclusions: The CIPP framework was successfully used to evaluate the Teaching Scholars Program. Areas of improvement were identified, including changing the program for input (add education lectures customized to faculty interests) and process (formally designate an experienced mentor to faculty).
View details for DOI 10.46374/volxxiv_issue4_chen
View details for PubMedID 36545369
The significance of widely split P waves: a case report.
Journal of medical case reports
2022; 16 (1): 197
BACKGROUND: P wave morphology on electrocardiogram is often overlooked but indicates abnormal cardiac conduction from various etiologies. Split P waves on electrocardiogram have been reported previously but not in a perioperative setting.CASE PRESENTATION: A 69-year-old Caucasian male patient with widely split P waves on his preoperative electrocardiogram was scheduled for a reimplantation right total hip replacement under a combined spinal-general anesthetic technique. The patient was evaluated prior to surgery by a cardiologist and the preoperative anesthesia clinic without any comment on the abnormal P wave morphology on electrocardiogram. The patient was cleared to proceed with anesthesia and surgery. Following induction of general anesthesia, his cardiac rhythm changed to a Mobitz type II pattern. The surgical procedure was cancelled, and a permanent cardiac pacemaker was inserted.CONCLUSIONS: Anesthesiologists should be aware that the presence of widely split P waves on electrocardiogram indicates the presence of atrial conduction abnormalities, likely from an ischemic or infiltrative process that can lead to more serious cardiac arrhythmias. P wave morphology should be observed and noted during the perioperative period for all patients.
View details for DOI 10.1186/s13256-022-03432-5
View details for PubMedID 35596188
Preoperative left ventricular diastolic dysfunction: outcomes after orthotopic liver transplantation
LIPPINCOTT WILLIAMS & WILKINS. 2021: 500-501
View details for Web of Science ID 000752526600216
- Development of an Objective Structured Clinical Examination Using the American Board of Anesthesiology Content Outline for the Objective Structured Clinical Examination Component of the APPLIED Certification Examination A & A PRACTICE 2018; 11 (7): 193–97
Development of an Objective Structured Clinical Examination Using the American Board of Anesthesiology Content Outline for the Objective Structured Clinical Examination Component of the APPLIED Certification Examination.
The goal of this study was to use the American Board of Anesthesiology Objective Structured Clinical Examination (OSCE) content outline as a blueprint to develop and administer a 9-station mock OSCE with station-specific checklists to senior residents (n = 14). The G- and Ф-coefficient reliability estimates were 0.76 and 0.61, respectively. Residents judged the scenarios as either extremely or somewhat realistic (88%). It is feasible to develop and administer a mock OSCE with rigorous psychometric characteristics.
View details for PubMedID 29688921