ABSTRACT
BACKGROUND: Virtual surgical planning (VSP) for composite microvascular free flaps has become standard of care for oncologic head and neck reconstruction. Controversy remains as to the use of three-dimensional (3D)-printed titanium patient-specific implants (PSIs) versus hand-bent stock reconstruction plates. Proponents of PSIs cite improved surgical accuracy, reduced operative times, and improved clinical outcomes. Detractors purport increased cost associated with PSIs and presumed equivalent accuracy with less expensive stock plates. PURPOSE: The study purpose was to measure and compare the 3D-volumetric accuracy of PSI versus stock reconstruction plates among subjects undergoing VSP-guided mandibular fibular free flap reconstruction. STUDY DESIGN, SETTING, SAMPLE: A retrospective cohort study of subjects undergoing VSP-guided fibular free flap reconstructions at Mayo Clinic between 2016 and 2023 was performed. Subjects were excluded for non-VSP guidance, midfacial reconstruction, nonfibular free flaps, and lack of requisite study variables. PREDICTOR VARIABLE: The primary predictor was the type of reconstruction plate utilized (PSI vs stock plate). MAIN OUTCOME VARIABLE: The main outcome was volumetric surgical accuracy of the final reconstruction compared to the preoperative surgical plan by root mean square error (RMSE) calculation. Lower RMSE values indicated a higher surgical accuracy. COVARIATES: Covariates included age, sex, race, smoking status, American Society of Anesthesiologists Physical Status Classification System, Charlson Comorbidity Index, preoperative diagnosis, and number of fibular segments. ANALYSES: Differences in surgical accuracy were assessed between preoperative and postoperative segmented scans using volumetric overlays from which RMSE values were calculated. Univariate and multivariate modeling of plate type to RMSE calculation was performed. Statistical significance set to P < .05. RESULTS: Total of 130 subjects were identified, 105 PSI and 25 stock plates. Calculated mean RMSE in millimeters (mm) for stock plates was 1.46 (standard deviation: 0.33) and 1.15 (standard deviation: 0.36) for PSIs. Univariate modeling demonstrated a statistically significant difference in RMSE of 0.31 (95% confidence interval: 0.16-0.47) (P < .001) equating to a 21.2% (P < .001) improved volumetric surgical accuracy for PSIs. The association of improved volumetric accuracy with PSIs has been maintained in all multivariate models controlling for confounding. CONCLUSION AND RELEVANCE: In modern era VSP-guided head and neck fibular free flap reconstruction, patient-specific 3D-printed titanium implants confer a statistically significant improvement in volumetric surgical accuracy over stock reconstruction plates.
ABSTRACT
BACKGROUND: The aim of this clinical study was to evaluate the efficacy of neurobehavioral, hemodynamics and sedative characteristics of dexmedetomidine compared with morphine and midazolam-based regimen after cardiac surgery at equivalent levels of sedation and analgesia in improving clinically relevant outcomes such as delirium. METHODS: Sixty patients were randomly allocated into one of two equal groups: group A = 30 patients received dexmedetomidine infusion (0.4-0.7 µg/kg/h) and Group B = 30 patients received morphine in a dose of 10-50 µg/kg/h as an analgesic with midazolam in a dose of 0.05 mg/kg up to 0.2 mg/kg as a sedative repeated as needed. Titration of the study medication infusions was conducted to maintain light sedation (Richmond agitation-sedation scale) (-2 to +1). Primary outcome was the prevalence of delirium measured daily through confusion assessment method for intensive care. RESULTS: Group A was associated with shorter length of mechanical ventilation, significant shorter duration of intensive care unit (ICU) stay (P = 0.038), and lower risk of delirium following cardiac surgery compared to Group B. Group A showed statistically significant decrease in heart rate values 4 h after ICU admission (P = 0.015) without significant bradycardia. Group A had lower fentanyl consumption following cardiac surgery compared to Group B. CONCLUSION: Dexmedetomidine significantly reduced the length of stay in ICU in adult cardiac surgery with no significant reduction in the incidence of postoperative delirium compared to morphine and midazolam.
ABSTRACT
Advanced thermobaric explosives have become one of the urgent requirements when targeting caves, fortified structures, and bunkers. Highly metal-based systems are designed to exploit the secondary combustion resulted from active metal particles; thus sustained overpressure and additional thermal loadings can be achieved. This study, reports on a novel approach for chemical composition optimization using thermochemical calculations in an attempt to achieve the highest explosion power. Shock wave resulted from thermobaric explosives (TBX) was simulated using ANSYS(®) AUTODYN(®) 2D hydrocode. Nanoscopic fuel-rich thermobaric charge was prepared by pressing technique; static field test was conducted. Comparative studies of modeled pressure-time histories to practical measurements were conducted. Good agreement between numerical modeling and experimental measurements was observed, particularly in terms of the prediction of wider overpressure profile which is the main characteristics of TBX. The TBX wider overpressure profile was ascribed to the secondary shock wave resulted from fuel combustion. The shock wave duration time and its decay pattern were acceptably predicted. Effective lethal fire-ball duration up to 50ms was achieved and evaluated using image analysis technique. The extended fire-ball duration was correlated to the additional thermal loading due to active metal fuel combustion. The tailored thermobaric charge exhibited an increase in the total impulse by 40-45% compared with reference charge.
ABSTRACT
PURPOSE: To compare the effectiveness of levosimendan and dobutamine in reducing pulmonary artery pressure (PAP) and increasing cardiac output for children undergoing cardiac surgery. PATIENTS AND METHODS: The study included 50 patients with high systolic pulmonary artery pressure (PAP) undergoing surgical repair of cardiac septal defects. Patients were randomly allocated to two equal groups: group L received levosimendan and group D received dobutamine. PAP was measured preoperatively, by use of transthoracic echocardiography (baseline), intraoperatively, directly, by use of a 22-gauge catheter inserted in the pulmonary artery, and postoperatively, by use of transesophageal echocardiography (TEE). Cardiac index (CI) was recorded by use of a transesophageal 4-MHz Doppler probe. RESULTS: Both drugs significantly reduced PAP compared with the level at the time of induction of anesthesia. Mean PAP measurement before chest closure, 1 and 20 h after ICU admission were significantly lower for patients who received levosimendan (32.7 ± 4.1, 25.8 ± 2.8, 19.8 ± 2 mmHg, respectively) than for those who received dobutamine (37.6 ± 2.75, 32.8 ± 2.36, 26.5 ± 2.2 mmHg, respectively). Both drugs significantly improved CI compared with its level at the time of induction of anesthesia. Mean CI measurements 5 min after weaning from cardiopulmonary bypass (CPB) until 20 h after ICU admission were significantly higher for patients who received levosimendan than for those who received dobutamine (3.55 ± 0.35, 3.8 ± 0.36, 3.81 ± 0.34, respectively, in group L vs. 3.4 ± 0.36, 3.6 ± 0.33, 3.66 ± 0.29, respectively, in group D). CONCLUSION: Levosimendan is better than dobutamine for treatment of pulmonary hypertension of children undergoing cardiac surgery.
