Further development of spinal cord retreatment dose estimation: including radiotherapy with protons and light ions.

PURPOSE: A graphical user interface (GUI) was developed to aid in the assessment of changes in the radiation tolerance of spinal cord/similar central nervous system tissues with time between two individual treatment courses. METHODS: The GUI allows any combination of photons, protons (or ions) to be used as the initial, or retreatment, radiotherapy courses. Allowances for clinical circumstances, of reduced tolerance, can also be made. The radiobiological model was published previously and has been incorporated with additional checks and safety features, to be as safe to use as possible. The proton option includes use of a fixed RBE of 1.1 (set as the default), or a variable RBE, the latter depending on the proton linear energy transfer (LET) for organs at risk. This second LET-based approach can also be used for ions, by changing the LET parameters. RESULTS: GUI screenshots are used to show the input and output parameters for different clinical situations used in worked examples. The results from the GUI are in agreement with manual calculations, but the results are now rapidly available without tedious and error-prone manual computations. The software outputs provide a maximum dose limit boundary, which should not be exceeded. Clinicians may also choose to further lower the number of treatment fractions, whilst using the same dose per fraction (or conversely a lower dose per fraction but with the same number of fractions) in order to achieve the intended clinical benefit as safely as possible. CONCLUSIONS: The new GUI will allow scientific-based estimations of time related radiation tolerance changes in the spinal cord and similar central nervous tissues (optic chiasm, brainstem), which can be used to guide the choice of retreatment dose fractionation schedules, with either photons, protons or ions.

Covid-19 transmission modelling of students returning home from university.

We provide an open-source model to estimate the number of secondary Covid-19 infections caused by potentially infectious students returning from university to private homes with other occupants. Using a Monte-Carlo method and data derived from UK sources, we predict that an infectious student would, on average, infect 0.94 other household members. Or, as a rule of thumb, each infected student would generate (just less than) one secondary within-household infection. The total number of secondary cases for all returning students is dependent on the virus prevalence within each student population at the time of their departure from campus back home. Although the proposed estimation method is general and robust, the results are sensitive to the input data. We provide Matlab code and a helpful online app (http://bit.ly/Secondary_infections_app) that can be used to estimate numbers of secondary infections based on local parameter values. This can be used worldwide to support policy making.

Percutaneous Tracheostomy under Bronchoscopic Visualization Does Not Affect Short-Term or Long-Term Complications.

Percutaneous tracheostomy is a safe and effective bedside procedure. Some advocate the use of bronchoscopy during the procedure to reduce the rate of complications. We evaluated our complication rate in trauma patients undergoing percutaneous tracheostomy with and without bronchoscopic guidance to ascertain if there was a difference in the rate of complications. A retrospective review of all tracheostomies performed in critically ill trauma patients was performed using the trauma registry from an urban, Level I Trauma Center. Bronchoscopy assistance was used based on surgeon preference. Standard statistical methodology was used to determine if there was a difference in complication rates for procedures performed with and without the bronchoscope. From January 2007, to April 2016, 649 patients underwent modified percuteaneous tracheostomy; 289 with the aid of a bronchoscope and 360 without. There were no statistically significant differences in any type of complication regardless of utilization of a bronchoscope. The addition of bronchoscopy provides several theoretical benefits when performing percutaneous tracheostomy. Our findings, however, do not demonstrate a statistically significant difference in complications between procedures performed with and without a bronchoscope. Use of the bronchoscope should, therefore, be left to the discretion of the performing physician.

Time to resuscitate a sacred cow...with normal saline.

Normal saline (NS) is not used for trauma resuscitation because of its potential for acidosis. Lactated Ringer's (LR) is preferred instead. However, the two crystalloids have never been compared in trauma patients. We hypothesized that NS would be an acceptable fluid for resuscitation in the trauma patient. In 2011, a Level I trauma center switched resuscitation fluid from LR to NS. Admissions before and after the change were retrospectively reviewed. Demographics, vitals, blood work, and fluid intake were recorded over 24 hours. Acidosis level, stratified by Injury Severity Score (ISS), was compared. Four hundred ten patients were included, 207 in the LR cohort and 203 in the NS. Chloride (LR 105.26 ± 4.75 vs NS 106.48 ± 4.19), base excess (-2.53 ± 3.77 vs -3.28 ± 4.15), pH (7.37 ± 0.08 vs 7.36 ± 0.07), and bicarbonate (22.83 ± 3.45 vs 21.65 ± 5.06) were statistically different but not clinically significant. This was also true when results were stratified by ISS. In addition, there was no difference in the number of blood gases drawn between the groups (584 vs 544, P = nonsignificant). NS resuscitation is a safe, viable alternative to LR in the trauma population studied. Its use carries a potentially substantial cost savings on a national level.