COVID-2019 Alert

The latest information about the 2019 Novel Coronavirus, including vaccine clinics for children ages 6 months and older.

La información más reciente sobre el nuevo Coronavirus de 2019, incluidas las clínicas de vacunación para niños de 6 meses en adelante.


Alexander Schmidt, Visiting

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Work and Education

Professional Education

Justus Liebig Universitat, giessen, Germany, 5/10/2007


Kantonsspital St Gallen Surgery Training, St Gallen, Switzerland, 6/30/2008


Kantonsspital St Gallen Anesthesiology Training, St Gallen, Switzerland, 7/31/2011


University Children's Hospital Zurich, Zurich, Switzerland, 9/30/2012

University Hospital Zurich Anesthesiology Training, Zurich, Switzerland, 11/30/2014

Board Certifications

Anesthesia, Swiss Medical Federation FMH

All Publications

Acute Hemodynamics in the Fontan Circulation: Open-Label Study of Vasopressin. Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies Adamson, G. T., Yu, J., Ramamoorthy, C., Peng, L. F., Taylor, A., Lennig, M., Schmidt, A. R., Feinstein, J. A., Navaratnam, M. 2023


OBJECTIVE: To describe the acute hemodynamic effect of vasopressin on the Fontan circulation, including systemic and pulmonary pressures and resistances, left atrial pressure, and cardiac index.DESIGN: Prospective, open-label, nonrandomized study (NCT04463394).SETTING: Cardiac catheterization laboratory at Lucile Packard Children's Hospital, Stanford.PATIENTS: Patients 3-50 years old with a Fontan circulation who were referred to the cardiac catheterization laboratory for hemodynamic assessment and/or intervention.INTERVENTIONS: A 0.03 U/kg IV (maximum dose 1 unit) bolus of vasopressin was administered over 5 minutes, followed by a maintenance infusion of 0.3 mU/kg/min (maximum dose 0.03 U/min).MEASUREMENTS AND MAIN RESULTS: Comprehensive cardiac catheterization measurements before and after vasopressin administration. Measurements included pulmonary artery, atrial, and systemic arterial pressures, oxygen saturations, and systemic and pulmonary flows and resistances. There were 28 patients studied. Median age was 13.5 (9.1, 17) years, and 16 (57%) patients had a single or dominant right ventricle. Following vasopressin administration, systolic blood pressure and systemic vascular resistance (SVR) increased by 17.5 (13.0, 22.8) mm Hg (Z value -4.6, p < 0.001) and 3.8 (1.8, 7.5) Wood Units (Z value -4.6, p < 0.001), respectively. The pulmonary vascular resistance (PVR) decreased by 0.40.4 WU (t statistic 6.2, p < 0.001), and the left atrial pressure increased by 1.0 (0.0, 2.0) mm Hg (Z value -3.5, p < 0.001). The PVR:SVR decreased by 0.040.03 (t statistic 8.1, p < 0.001). Neither the pulmonary artery pressure (median difference 0.0 [-1.0, 1.0], Z value -0.4, p = 0.69) nor cardiac index (0.10.3, t statistic -1.4, p = 0.18) changed significantly. There were no adverse events.CONCLUSIONS: In Fontan patients undergoing cardiac catheterization, vasopressin administration resulted in a significant increase in systolic blood pressure, SVR, and left atrial pressure, decrease in PVR, and no change in cardiac index or pulmonary artery pressure. These findings suggest that in Fontan patients vasopressin may be an option for treating systemic hypotension during sedation or general anesthesia.

View details for DOI 10.1097/PCC.0000000000003326

View details for PubMedID 37462430

Evaluation of continuous ampicillin/sulbactam infusion in critically ill patients. Life sciences Passon, S. G., Schmidt, A. R., Wittmann, M., Velten, M., Baehner, T. 2023; 320: 121567


Continuous infusion (CI) of beta-lactam-antibiotics may improve pharmacodynamics in critically ill patients, but resulting concentrations have not been studied. Therapeutic drug monitoring is increasingly used to ensure antibiotic concentration. The aim of this study is to evaluate therapeutic ampicillin/sulbactam concentrations of a continuous infusion regimen.Medical records of all patients admitted to ICU between January 2019 and December 2020 were retrospectively reviewed. Each patient received a 2/1g ampicillin/sulbactam loading dose, followed by a continuous infusion of 8/4g per 24h. Ampicillin serum concentrations were measured. Main outcomes were reaching of plasma concentrations breakpoint defined by minimum inhibitory concentration (MIC at 8mg/l) and 4-fold MIC (MIC at 32mg/l) during steady state of CI.In 50 patients a total of 60 concentration measurements were performed. The first concentration was measured after a median of 29h (IQR 21-61h). Mean ampicillin concentration was 62.639.1mg/l. Furthermore, serum concentrations exceeded the defined MIC breakpoint in all measurements (100%) and were above the 4-fold MIC in 43 analyses (71.1%). However, patients suffering from acute kidney injury exhibited significant higher serum concentrations (81.137.7mg/l vs. 38.224.8mg/l; p<0.001). Also, there was a negative correlation between ampicillin serum concentrations and GFR (r=-0.659; p<0.001).The described dosing regimen for ampicillin/sulbactam is safe with respect to the defined MIC breakpoints for ampicillin, and continuous subtherapeutic concentration is unlikely. However, with impaired renal function drug accumulation occurs, and with increased renal clearance, drug levels can be below the 4-fold MIC breakpoint.

View details for DOI 10.1016/j.lfs.2023.121567

View details for PubMedID 36907327

Pre-operative fasting in children: A guideline from the European Society of Anaesthesiology and Intensive Care. European journal of anaesthesiology Frykholm, P., Disma, N., Andersson, H., Beck, C., Bouvet, L., Cercueil, E., Elliott, E., Hofmann, J., Isserman, R., Klaucane, A., Kuhn, F., de Queiroz Siqueira, M., Rosen, D., Rudolph, D., Schmidt, A. R., Schmitz, A., Stocki, D., Sumpelmann, R., Stricker, P. A., Thomas, M., Veyckemans, F., Afshari, A. 2022; 39 (1): 4-25


Current paediatric anaesthetic fasting guidelines have recommended conservative fasting regimes for many years and have not altered much in the last decades. Recent publications have employed more liberal fasting regimes with no evidence of increased aspiration or regurgitation rates. In this first solely paediatric European Society of Anaesthesiology and Intensive Care (ESAIC) pre-operative fasting guideline, we aim to present aggregated and evidence-based summary recommendations to assist clinicians, healthcare providers, patients and parents. We identified six main topics for the literature search: studies comparing liberal with conservative regimens; impact of food composition; impact of comorbidity; the use of gastric ultrasound as a clinical tool; validation of gastric ultrasound for gastric content and gastric emptying studies; and early postoperative feeding. The literature search was performed by a professional librarian in collaboration with the ESAIC task force. Recommendations for reducing clear fluid fasting to 1h, reducing breast milk fasting to 3h, and allowing early postoperative feeding were the main results, with GRADE 1C or 1B evidence. The available evidence suggests that gastric ultrasound may be useful for clinical decision-making, and that allowing a 'light breakfast' may be well tolerated if the intake is well controlled. More research is needed in these areas as well as evaluation of how specific patient or treatment-related factors influence gastric emptying.

View details for DOI 10.1097/EJA.0000000000001599

View details for PubMedID 34857683

Bronchopulmonary Dysplasia. Paediatric anaesthesia Schmidt, A. R., Ramamoorthy, C. 2021


Bronchopulmonary dysplasia is the most frequent adverse outcome of prematurity. Before implementation of antenatal steroids and surfactant therapy bronchopulmonary dysplasia was mostly characterized by fibrotic, scarred and hyper-inflated lungs due to pulmonary injury following mechanical ventilation and oxygen toxicity. With advances in neonatal medicine this "old" bronchopulmonary dysplasia has changed to a "new" bronchopulmonary dysplasia characterized by an arrest in lung growth, leading to alveolar simplification and pulmonary vascular dysangiogenesis. While the old definition was based on the need for oxygen supplementation at a postnatal age of 28 days or at a corrected gestational age of 36 weeks, the newer definition looks at the mode of respiratory support required (e.g., invasive versus non-invasive) and then graded as mild, moderate or severe. Patients with bronchopulmonary dysplasia may present with significantly impaired pulmonary function, reactive airways disease or exercise intolerance. Over time these patients may develop asthma or chronic obstructive pulmonary disease. The most serious long term complication is the development of pulmonary vascular disease and pulmonary hypertension. Medical treatment often includes diuretics, steroids, bronchodilators or oxygen supplementation and in the presence of pulmonary hypertension medication to decrease the pulmonary vascular resistance. Perioperative anesthetic risk is increased in children with pulmonary hypertension. These patients might require additional diagnostic imaging and plans for increased resource allocation such as post-operative intensive care admission.

View details for DOI 10.1111/pan.14365

View details for PubMedID 34877749

Pre-operative fasting times for clear liquids at a tertiary children's hospital; what can be improved? Anesthesia and pain medicine Schmidt, A. R., Fehr, J., Man, J., D'Souza, G., Wang, E., Claure, R., Mendoza, J. 2021


Background: The goal of preoperative fasting is to prevent pulmonary aspiration during general anesthesia. Fasting times are often prolonged leading to patient discomfort and risk for adverse events. This retrospective quality improvement survey evaluated effective nil-per-os (NPO) times and causes for prolonged NPO times with the aim to suggest improvement strategies by a newly founded fasting task force.Methods: Data from all electronic anesthesia records from 2019 at our institution were reviewed for fasting times. Our NPO instructions follow American Society of Anesthesiology guidelines and are calculated based on the patient's arrival time (90 min before operating room [OR] time). Primary outcome was the effective NPO time for clear liquids, secondary outcomes were incidence of delays and the parental compliance with the NPO instructions. Data are presented as median (interquartile range).Results: In total 9,625 cases were included in the analysis. NPO time was documented in 72.1% with a median effective NPO time of 7:13 h (7:36). OR in room times were documented in 72.8%, 2,075 (29.5%; median time 0:10 h [0:21]) were earlier and 4,939 (70.5%; median time 0:29 h [0:54]) were later than scheduled. Parental NPO compliance showed a median deviation for clear liquid intake of 0:55 h (8:30).Conclusions: This study revealed that effective NPO times were longer than current ASA guidelines. Contributing causes include case delays and parental non-compliance to NPO instructions. Thus, task force recommendations include change NPO instruction calculations to scheduled OR time versus arrival time, and encourage parents to give their child clear liquids at the instructed time.

View details for DOI 10.17085/apm.21025

View details for PubMedID 34289299

Augmented Reality Visualization Tool For The Future of Tactical Combat Casualty Care. The journal of trauma and acute care surgery Leuze, C., Zoellner, A., Schmidt, A. R., Fischer, M. J., Cushing, R. E., Joltes, K., Zientara, G. P. 2021


The objective of this project was to identify and develop software for an Augmented Reality (AR) application that runs on the US Army Integrated Visual Augmentation System (IVAS) to support a medical caregiver during training and combat casualty care (TC3) scenarios. In this AR-TC3 application, human anatomy of individual soldiers obtained pre-deployment is superimposed on the view of an injured warfighter through the IVAS. This offers insight into the anatomy of the injured warfighter to advance treatment in austere environments.In this article, we describe various software components required for an AR-TC3-tool. These include a body pose tracking system to track the patient's body pose, a virtual rendering of a human anatomy avatar, speech input to control the application and rendering techniques to visualize the virtual anatomy and treatment information on the AR display. We then implemented speech commands and visualization for four common medical scenarios including injury of a limb, a blast to the pelvis, cricothyrotomy, and a pneumothorax on the Microsoft Hololens 1.The software is designed for a forward surgical care tool on the US Army IVAS, with the intention to provide the medical caregiver with a unique ability to quickly assess affected internal anatomy. The current software components still had some limitations with respect to speech recognition reliability during noise and body pose tracking. These will likely be improved with the improved hardware of the IVAS, which is based on a modified Hololens 2.LEVEL OF EVIDENCE: Basic science paper.

View details for DOI 10.1097/TA.0000000000003263

View details for PubMedID 33938509

Impact of Modified Anesthesia Management for Pediatric Patients With Williams Syndrome. Journal of cardiothoracic and vascular anesthesia Schmidt, A. R., Collins, R. T., Adusumelli, Y., Ramamoorthy, C., Weng, Y., MacMillen, K. L., Navaratnam, M. 2021


OBJECTIVE: This study compared the percent change in systolic blood pressure and the incidence of adverse cardiac events (ACEs; defined as cardiac arrest, cardiopulmonary resuscitation, arrhythmias, or ST-segment changes) during anesthesia induction in patients with Williams syndrome (WS) before and after implementation of a perioperative management strategy.DESIGN: Retrospective observational cohort study.SETTING: Single quaternary academic referral center.PARTICIPANTS: The authors reviewed the records of all children with WS at the authors' institution who underwent general anesthesia for cardiac catheterization, diagnostic imaging, or any type of surgery between November 2008 and August 2019. The authors identified 142 patients with WS, 48 of whom underwent 118 general anesthesia administrations. A historic group (HG) was compared with the intervention group (IG).INTERVENTIONS: Change in perioperative management (three-stage risk stratification: preoperative intravenous hydration, intravenous anesthesia induction, and early use of vasoactives).MEASUREMENTS AND MAIN RESULTS: The authors determined event rates within 60 minutes of anesthesia induction. Standardized mean difference (SMD) was calculated (SMD >0.2 suggests clinically meaningful difference). Sixty-seven general anesthesia encounters were recorded in the HG (mean age, 4.8 years; mean weight, 16.3 kg) and 51 in the IG (mean age, 6.0 years; mean weight, 18.2 kg). The change in systolic blood pressure was -17.5% (-30.0, -5.0) in the HG versus -9% (-18.0, 5.0) in the IG (p=0.015; SMD=0.419), and the incidence of ACEs was 6% in the HG and 2% in the IG (p=0.542; SMD=0.207).CONCLUSIONS: Preoperative risk stratification, preoperative intravenous hydration, intravenous induction, and early use of continuous vasoactives resulted in greater hemodynamic stability, with a 2% incidence of ACEs.

View details for DOI 10.1053/j.jvca.2021.04.019

View details for PubMedID 34049787

Rabbit training model for establishing an emergency front of neck airway in children. British journal of anaesthesia Both, C. P., Diem, B. n., Alonso, E. n., Kemper, M. n., Weiss, M. n., Schmidt, A. R., Deisenberg, M. n., Thomas, J. n. 2021


A 'cannot intubate, cannot oxygenate' (CICO) situation is rare in paediatric anaesthesia, but can always occur in children under certain emergency situations. There is a paucity of literature on specific procedures for securing an emergency invasive airway in children younger than 6 yr. A modified emergency front of neck access (eFONA) technique using a rabbit cadaver model was developed to teach invasive airway protection in a CICO situation in children.After watching an instructional video of our eFONA technique (tracheotomy, intubation with Frova catheter over which a tracheal tube is inserted), 29 anaesthesiologists performed two separate attempts on rabbit cadavers. The primary outcome was the success rate and the performance time overall and in subgroups of trained and untrained participants.The overall success rate across 58 tracheotomies was 95% and the median performance time was 67 s (95% confidence interval [CI], 56-76). Performance time decreased from the first to the second attempt from 72 s (95% CI, 57-81) to 61 s (95% CI, 50-81). Performance time was 59 s (95% CI, 49-79) for untrained participants and 72 s (95% CI, 62-81) for trained participants. Clinical experience and age of the participants was not correlated with performance time, whereas the length of the tracheotomy incision showed a significant correlation (P=0.006).This eFONA training model for children facilitates rapid skill acquisition under realistic anatomical conditions to perform an emergency invasive airway in children younger than 2 yr.

View details for DOI 10.1016/j.bja.2020.12.032

View details for PubMedID 33526261