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Lung transplant (LTx) recipients with required immunosuppression often exhibit kidney injury over time. For some, subsequent renal transplant (RTx) can be offered to potentially prolong survival and improve quality of life. Factors leading to kidney injury after LTx have been studied, but patient characteristics prior to LTx that may predict outcomes of subsequent RTx are not yet clear. Thus, we aimed to analyze prognostic factors for RTx after LTx and the impact of RTx on these patients. We retrospectively reviewed the ISHLT database from 1994 to 2018 for recipients with RTx at any time after LTx. Controls with no RTx post-LTx were matched 4:1 to qualifying cases on age, BMI, lung diagnosis, year of LTx, severe renal dysfunction, and dialysis. Data at LTx were compared using Kruskal Wallis and chi-square tests. Kaplan-Meier methods with a landmark at median time to RTx were used to account for immortal time bias between LTx and RTx among cases. We compared 385 RTx post-LTx to 1540 with no RTx post-LTx. RTx post-LTx patients were predominantly diagnosed with cystic fibrosis (32.7%) and COPD (26.2%), with a median time of 7.1 years to RTx after LTx. Compared to controls, RTx post-LTx patients were younger at LTx (45.9 vs 50.4 years, p<0.0001), had a significant history of diabetes (20.2 vs 16.9%, p=0.003), and more often had at least two documented IV-treated pulmonary sepsis episodes in the year prior to listing (20.5 vs 13.2%, p=0.0014). Importantly, RTx post-LTx improved survival compared to LTx only at 10, 15, and 20 years (p <0.0001; 85.3 vs 65.8%, 59.4 vs 24.8%, 43.4 vs 7.5%, respectively, Figure 1). No differences were identified in chronic steroid use, history of dialysis, and bronchiolitis obliterans syndrome. Evaluation of the prognostic factors identified herein may help predict the need for RTx in patients undergoing LTx. Notably, RTx post-LTx in patients who meet such prognostic criteria may have improved long-term survival. Thus, early referral of suitable candidates should be considered. [ABSTRACT FROM AUTHOR]

Martian orbital and lander measurements revealed strong (∼1–2 orders of magnitude greater than Earth) crustal magnetic anomalies and the lack of an active detectable core dynamo. This strong crustal magnetization remains unexplained given that models of an ancient core dynamo on Mars predict surface field strengths comparable to modern Earth. We explored the relationship between Mars' crustal magnetization and its composition in multivariate space. We identified that 530 and 1,000 nm absorptions (from orbital spectrometers) have unique correlations with crustal magnetization in the Terra Sirenum‐Terra Cimmeria region and ∼13% of the variance of the magnetization can be attributed to these correlations. Because we do not expect the topmost material, detectable by the orbital spectrometers, to retain magnetization from an ancient core dynamo, we propose this material is compositionally similar to the bulk rock below it, which is more likely to retain magnetization. Therefore, the observed variance is a lower limit. Plain Language Summary: Currently Mars has no global magnetic field. However, at some point it did have a global magnetic field. Instruments from past missions have spotted patches on Mars' surface that are strongly magnetized. This can be explained by the fact that the crust was formed during a time when the global magnetic field was present, and so it locked in on that magnetic field. Previous models suggest that when Mars' global magnetic field was present, it was approximately of the same strength as Earth's current field. A magnetic field of this strength would not have produced such a strongly magnetized crust. Therefore, the magnetization strength of those patches is a mystery. We explored the relationships between the strength of the magnetic field on the surface and the composition of the crust. Our findings show that in the area with the strongest magnetic patches, there is a verifiable positive correlation between the magnetic field and mineralogical data. This leads us to believe that the composition of those patches enables them to record the magnetic field exceptionally well. Therefore, Mars' ancient global magnetic field did not need to be anomalously large to produce the strongly magnetized crust we observe. Key Points: The strong magnetization observed in the Terra Sirenum‐Terra Cimmeria region is at least partially due to compositional enhancementThe Terra Sirenum‐Terra Cimmeria region has not experienced widespread demagnetization processes since formationThe magnetization in the Terra Sirenum‐Terra Cimmeria region is carried in the bulk rock with representative materials exposed at the surface [ABSTRACT FROM AUTHOR]

The parameterization of the magnetospheric field contribution, generated by currents flowing in the magnetosphere is of major importance for the analysis of Mercury's internal magnetic field. Using a combination of the Gauss and the Mie representation (toroidal–poloidal decomposition) for the parameterization of the magnetic field enables the analysis of magnetic field data measured in current carrying regions in the vicinity of Mercury. In view of the BepiColombo mission, the magnetic field resulting from the plasma interaction of Mercury with the solar wind is simulated with a hybrid simulation code and the internal Gauss coefficients for the dipole, quadrupole and octupole field are reconstructed from the data, evaluated along the prospective trajectories of the Mercury Planetary Orbiter (MPO) using Capon's method. Especially, it turns out that a high-precision determination of Mercury's octupole field is expectable from the future analysis of the magnetic field data measured by the magnetometer on board MPO. Furthermore, magnetic field data of the MESSENGER mission are analyzed and the reconstructed internal Gauss coefficients are in reasonable agreement with the results from more conventional methods such as the least-square fit. [ABSTRACT FROM AUTHOR]

The article discusses a study on the absence of crustal magnetic fields above the martian basins Hellas, Argyre, and Isidis. It mentions that dynamo was present both before and after the formation of the basins Hellas, Utopia, Argyre, and Isidis. It also mentions that Earth-like dynamo is consistent with the absence of magnetization within large basins if the impacts excavated large portions of strongly magnetic crust and exposed deeper material with lower concentrations of magnetic minerals.

Donation after circulatory death (DCD) is an emerging but underutilized procurement strategy to increase the donor pool in heart and lung transplantation. In recent years there has been an emergence of heart DCD in the US due to new technologies such as normothermic regional perfusion (NRP) and portable ex vivo heart perfusion. Given this increased utilization of cardiac DCD donor heart, we wanted to investigate the impact of DCD heart procurement in concurrent lung donation and implantation at a national level. We reviewed the United Network for Organ Sharing (UNOS) database for registered heart donation between December 2019 and March 2022. DCD donors were separated from Donation after brain death (DBD) donors and further categorized based on concomitant organ procurement of lung and heart, or heart only procurement. Normothermic regional perfusion was identified among DCD donors with a time from asystole to cross clamp greater than 15 minutes. Chi-squared and Kruskal-Wallis tests were applied to compare characteristics and outcomes. Kaplan Meier survival analysis was performed. A total of 8,802 heart procurements consisted of 332 DCD donors and 8,470 DBD donors. Concomitant lung procurement was significantly lower among DCD heart procurements (64 patients, 19.3%) than DBD heart procurements (3,217 patients, 38.0%, p<0.001). The use-rate of transplanted lungs in the setting of concomitant other thoracic organ procurement is 13.6% in DCD donors (8 single, 37 double), whereas it is significantly higher in brain death donors at 38% (p <0.001). Out of the 64 DCD donors, 22 donors had lungs that were retrieved but discarded (34.4%). NRP was performed in 37.3% of DCD donors (124 out of 332) and there was no difference in lung utilization between DCD + NRP vs DCD (20.2% and 18.8%). There was also no difference in lung recipient 1-year survival between DCD + NRP and DCD (Figure 1, p =0.184). While there has been an increase in national use of hearts after DCD procurement, concomitant lung allograft procurement and transplantation is unexpectedly low. This is further emphasized when compared to the published rate of lung utilization in brain death donors. Further studies are warranted to investigate the reasons underlying these differences, but it presents an exciting opportunity for expansion of lung donation. [ABSTRACT FROM AUTHOR]

Abstract: We describe a method to estimate the total electron content (TEC) of the Mars ionosphere from the output parameters of an algorithm, called the Contrast Method (Picardi, G., Sorge, S. [2000]. Proc. SPIE. Eighth International Conference on Ground Penetrating Radar, vol. 4084, pp. 624–629; Ilyushin, Ya.A., Kunitsyn, V.E. [2004]. J. Commun. Technol. Electron. 49, 154–165), which allows to correct the phase distortion of the echoes recorded by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) (Picardi, G. et al. [2005]. Science 310, 1925–1928) in its subsurface mode. Based on the TEC values evaluated during 6years of MARSIS activity, corresponding to about 4600 orbits, in this paper we present a global map of the night side TEC variations, which correlates well with the magnetic field model derived from Mars Global Surveyor (MGS) Magnetometer/Electron Reflectometer (MAG/ER) data. In particular, we demonstrate that regions of enhanced TEC preferentially correspond to areas where crustal magnetic field lines are quasi perpendicular to the martian surface; moreover, we demonstrate that, in regions where the magnetic field is predominantly nearly vertical, enhanced TEC values correlate with higher field intensities, while in regions where the magnetic field is predominantly nearly horizontal, such correlation is not observed. As already suggested in the past by other authors, we suggest that increased TEC values may be related to the precipitation of electrons from the martian magnetospheric tail along vertical crustal magnetic field lines. [Copyright &y& Elsevier]

Mariner 10 measurements proved the existence of a large-scale internal magnetic field on Mercury. The observed field amplitude, however, is too weak to be compatible with typical convective planetary dynamos. The Lorentz force based on an extrapolation of Mariner 10 data to the dynamo region is 10−4 times smaller than the Coriolis force. This is at odds with the idea that planetary dynamos are thought to work in the so-called magnetostrophic regime, where Coriolis force and Lorentz force should be of comparable magnitude. Recent convective dynamo simulations reviewed here seem to resolve this caveat. We show that the available convective power indeed suffices to drive a magnetostrophic dynamo even when the heat flow though Mercury’s core–mantle boundary is subadiabatic, as suggested by thermal evolution models. Two possible causes are analyzed that could explain why the observations do not reflect a stronger internal field. First, toroidal magnetic fields can be strong but are confined to the conductive core, and second, the observations do not resolve potentially strong small-scale contributions. We review different dynamo simulations that promote either or both effects by (1) strongly driving convection, (2) assuming a particularly small inner core, or (3) assuming a very large inner core. These models still fall somewhat short of explaining the low amplitude of Mariner 10 observations, but the incorporation of an additional effect helps to reach this goal: The subadiabatic heat flow through Mercury’s core–mantle boundary may cause the outer part of the core to be stably stratified, which would largely exclude convective motions in this region. The magnetic field, which is small scale, strong, and very time dependent in the lower convective part of the core, must diffuse through the stagnant layer. Here, the electromagnetic skin effect filters out the more rapidly varying high-order contributions and mainly leaves behind the weaker and slower varying dipole and quadrupole components (Christensen in Nature 444:1056–1058, ). Messenger and BepiColombo data will allow us to discriminate between the various models in terms of the magnetic fields spatial structure, its degree of axisymmetry, and its secular variation. [ABSTRACT FROM AUTHOR]

Observations of the geomagnetic field taken at Earth's surface and at satellite altitude are combined to construct continuous models of the geomagnetic field and its secular variation from 1957 to 2020. From these parent models, we derive candidate main field models for the epochs 2015 and 2020 to the 13th generation of the International Geomagnetic Reference Field (IGRF). The secular variation candidate model for the period 2020–2025 is derived from a forecast of the secular variation in 2022.5, which results from a multi-variate singular spectrum analysis of the secular variation from 1957 to 2020. [ABSTRACT FROM AUTHOR]

Patients with myeloproliferative neoplasms (MPNs) face chronic symptom burden. Online symptom assessment studies allow for recruitment of large numbers of motivated patients, but patient self-selection can lead to sampling bias. This study evaluated how gender representativeness in MPN symptom surveys and trials impacted symptom score mean estimates, using data from 4825 survey respondents and 291 trial participants with MPNs. The survey data showed that men participated at a rate roughly 50% less than what would be expected based on prevalence, and women reported higher scores than men on average for six of 10 symptoms. Together, this led to potential over estimation in six of 10 symptom score means (ranging from 5.8% to 15.3% overestimated). The trial data showed less gender-based sampling bias compared to the survey data. Studies utilizing online symptom surveys should implement study design features to recruit more men, assess for gender participation imbalances, and provide weighted estimates where appropriate.

Purpose: Lung transplantation (LTx) is a potential intervention for end-stage COVID-19 lung disease. Current literature is sparse regarding the outcomes of LTx for COVID-19 related acute respiratory distress syndrome (ARDS) and pulmonary fibrosis (PF). This study aims to characterize outcomes and patterns of LTx for COVID-19 related lung disease throughout the pandemic., Methods: Patients who underwent LTx during the pandemic for COVID-19 related lung disease were retrospectively identified using the UNOS registry. Demographics, as well as outcomes measures and nationwide patterns of care were collected and analyzed., Results: A total of 510 adult cases of LTx for COVID-19 (259 ARDS, 251 PF) were compared to 4,031 without COVID-19 (3,994 PF, 37 ARDS). Patients who received LTx for COVID-19 ARDS did not differ in 2-year survival when compared to those with COVID-19 PF (81.9% vs 77.2%, p = 0.4428). Compared to non-COVID-19 etiologies, COVID-19 ARDS patients had higher rates of stroke (2.3% vs 0%, p = 0.0005), lower rates of graft failure (12.8% vs 36.1%, p = 0.0003) and post-transplant ECMO (29.6% vs 41.7%, p = 0.0002), and improved 2-year survival following LTx (81.9% vs 61.7%, p = 0.0064). No difference in 2-year survival following LTx was observed between patients with COVID-19 and non-COVID-19 PF (77.2% vs 71.8%, p = 0.34). Rates of LTx spiked with variant emergence and declined with rounds of vaccination., Conclusion: Our results are consistent with early reports of survival outcomes following LTx for COVID-19 ARDS and PF while providing an increased layer of granularity. LTx may be considered as a safe and effective intervention for COVID-19 lung disease., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: After implementation of the Lung Allocation Score in 2005, idiopathic pulmonary fibrosis (IPF) emerged as the most common indication for lung transplantation (LT) in the United States. The age and comorbidity of patients undergoing LT have since increased, and the indications for LT have evolved. However, limited data have been used to analyze more recent outcomes among the IPF population., Methods: This study analyzed LTs for the primary indication of IPF by using the United Network for Organ Sharing database. An eras-based analysis was performed, comparing patient characteristics, survival, and related outcomes during 2005 to 2009 (era 1) and 2010 to 2014 (era 2) with χ 2 , Wilcoxon rank sum, and Kaplan-Meier analyses. The study compared 1-year survival from 2005 to 2020 and survival at milestones ranging from 1 month to 5 years. Two adjusted Cox proportional hazards models were conducted: 5-year survival by era and 1-year survival annually from 2010 to 2020., Results: From era 1 (n = 1818) to era 2 (n = 3227), the median age of LT recipients increased from 61 to 63 years (P < .001). The percentage of patients in the intensive care unit before LT climbed from 7.7% to 12.1% (P < .001), and the percentage of patients with diabetes grew from 17.9% to 19.4% (P = .003). Despite increased severity of illness, 5-year survival increased from 51.9% in era 1 to 55.2% in era 2 (P = .02). Adjusted modeling indicated that LT during era 2 featured a 17% hazard reduction compared with era 1 (hazard ratio, 0.83; 95% CI, 0.76-0.91)., Conclusions: Survival is improving for patients undergoing LT for IPF, despite the challenges of transplant recipients with progressively higher risk profiles., (Copyright © 2024 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Purpose: The standard recall period for the patient-reported outcomes version of the common terminology criteria for adverse events (PRO-CTCAE®) is the past 7 days, but there are contexts where a 24-hour recall may be desirable. The purpose of this analysis was to investigate the reliability and validity of a subset of PRO-CTCAE items captured using a 24-hour recall., Methods: 27 PRO-CTCAE items representing 14 symptomatic adverse events (AEs) were collected using both a 24-hour recall (24 h) and the standard 7 day recall (7d) in a sample of patients receiving active cancer treatment (n = 113). Using data captured with a PRO-CTCAE-24h on days 6 and 7, and 20 and 21, we computed intra-class correlation coefficients (ICC); an ICC ≥ 0.70 was interpreted as demonstrating high test-retest reliability. Correlations between PRO-CTCAE-24h items on day 7 and conceptually relevant EORTC QLQ-C30 domains were examined. In responsiveness analysis, patients were deemed changed if they had a one-point or greater change in the corresponding PRO-CTCAE-7d item (from week 0 to week 1)., Results: PRO-CTCAE-24h captured on two consecutive days demonstrated that 21 of 27 items (78%) had ICCs ≥ 0.70 (day 6/7 median ICC 0.76), (day 20/21 median ICC 0.84). Median correlation between attributes within a common AE was 0.75, and the median correlation between conceptually relevant EORTC QLQ-C30 domains and PRO-CTCAE-24 h items captured on day 7 was 0.44. In the analysis of responsiveness to change, the median standardized response mean (SRM) for patients with improvement was - 0.52 and that for patients with worsening was 0.71., Conclusion: A 24-hour recall period for PRO-CTCAE items has acceptable measurement properties and can inform day-to-day variations in symptomatic AEs when daily PRO-CTCAE administration is implemented in a clinical trial., (© 2023. The Author(s).)

Lung transplantation (LTx) using donation after circulatory death (DCD) donors has demonstrated equivalent outcomes compared to donation after brain dead (DBD) donors. However, data from the use of DCDs for high-risk (HR) recipients is limited. We performed a propensity match study to evaluate the impact of DCD transplantation on HR recipients. In addition, we assessed the effect of recipient profile (HR vs. non-HR) in DCDs and DBDs LTx. From 2009-2018, 1829 double lung transplants (DLTx) for HR recipients were identified. Of these, 131 were performed using DCD donors. There was no difference in survival between DCDs and DBDs among HR-DLTx recipients (p = 0.16). However, HR recipients had worse survival compared to non-HR recipients in DBD (p < 0.001) but not in DCD transplantation (p = 0.95). Our findings support that DCD lungs are appropriate for HR recipients and should not be considered inferior or higher-risk donors. Its use should be further stimulated rather than restricted., (Copyright © 2022 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Context: Summarizing longitudinal symptomatic adverse events during clinical trials is necessary for understanding treatment tolerability. The Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE) provides insight for capturing treatment tolerability within trials. Tolerability summary measures, such as the maximum score, are often used to communicate the potential negative symptoms both in the medical literature and directly to patients. Commonly, the proportions of present and severe symptomatic adverse events are used and reported between treatment arms among adverse event types. The toxicity index is also a summary measure previously applied to clinician-reported CTCAE data., Objectives: Apply the toxicity index to PRO-CTCAE data from the COMET-2 trial alongside the maximum score, then present and discuss considerations for using the toxicity index as a summary measure for communicating tolerability to patients and clinicians., Methods: Proportions of maximum PRO-CTCAE severity levels and median toxicity index were computed by arm using all trial data and adjusting for baseline symptoms., Results: Group-wise statistical differences were similar whether using severity level proportions or the toxicity index. The impact of adjusting for baseline symptoms was equivalently seen when comparing arms using severity rates or the toxicity index., Conclusion: The toxicity index is a useful method when ranking patients from those with the least to most symptomatic adverse event burden. This study showed the toxicity index can be applied to PRO-CTCAE data. Though as a tolerability summary measure, further study is needed to provide a clear clinical or patient-facing interpretation of the toxicity index., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

While devoid of an active magnetic field today, Mars possesses a remanent magnetic field which may reach several thousand nT locally. The exact origin, and the events which have shaped the crustal magnetization remain largely enigmatic. Three magnetic field datasets from two spacecraft collected over 13 cumulative years have sampled the martian magnetic field over a range of altitudes from 90 km up to 6000 km: a- Mars Global Surveyor (MGS) magnetometer (1997-2006); b- MGS Electron Reflectometer (1999-2006); c- MAVEN magnetometer (2014-today). In this paper we combine these complementary datasets for the first time to build a new model of the martian internal magnetic field. This new model improves upon previous ones in several aspects: comprehensive data coverage; refined data selection scheme; modified modeling scheme; discrete-to-continuous transformation of the model; increased model resolution. The new model has a spatial resolution of ~ 160 km at the surface, corresponding to spherical harmonic degree 134. It shows small scales and well defined features, which can now be associated with geological signatures.

Aim of Study: This study aims to quantify the relative impact of Dispatcher-Initiated Telephone cardiopulmonary resuscitation (TCPR) on survival and survival with favorable functional outcome after out-of-hospital cardiac arrest (OHCA) in a population of patients served by multiple emergency dispatch centers and more than 130 emergency medical services (EMS) agencies., Methods: We conducted a retrospective, observational study of EMS-treated adult (≥18 years) patients with OHCA of presumed cardiac origin in Arizona, between January 1, 2011, and December 31, 2014. We compared survival and functional outcome among three distinct groups of OHCA patients: those who received no CPR before EMS arrival (no CPR group); those who received BCPR before EMS arrival and prior to or without telephone CPR instructions (BCPR group); and those who received TCPR (TCPR group)., Results: In this study, 2310 of 4391 patients met the study criteria (median age, 62 years; IQR 50, 74; 1540 male). 32.8% received no CPR, 23.8% received Bystander-Initiated CPR and 43.4% received TCPR. Overall survival was 11.5%. Using no CPR as the reference group, the multivariate adjusted odds ratio for survival at hospital discharge was 1.51 (95% confidence interval [CI], 1.04, 2.18) for BCPR and 1.64 (95% CI, 1.16, 2.30) for TCPR. The multivariate adjusted odds ratio of favorable functional outcome at discharge was 1.58 (95% CI 1.05, 2.39) for BCPR and 1.56 (95% CI, 1.06, 2.31) for TCPR., Conclusion: TCPR is independently associated with improved survival and improved functional outcome after OHCA., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Aim: Emergency medical telecommunicators can play a key role in improving outcomes from out-of-hospital cardiac arrest (OHCA) by providing instructions for cardiopulmonary resuscitation (CPR) to callers. Telecommunicators, however, frequently encounter barriers that obstruct the Telephone CPR (TCPR) process. The nature and frequency of these barriers in public and residential locations have not been well investigated. The aim of this study is to identify the barriers to TCPR in public and residential locations., Methods: We conducted a retrospective study of audio recordings of EMS-confirmed OHCAs from eight regional 9-1-1 dispatch centers between January 2012 and December 2013., Results: We reviewed 1850 eligible cases (public location OHCAs: N=223 and residential location OHCAs: N=1627). Telecommunicators less frequently encountered barriers such as inability to calm callers in public than in residential locations (2.1% vs 8.5%, p=0.002) or inability to place victims on a hard flat surface (13.9% vs 25.4%, p<0.001). However, the barrier where callers were not with patients was more frequently observed in public than in residential locations (11.8% vs 2.7%, p<0.001)., Conclusions: This study revealed that barriers to TCPR are distributed differently across public and residential locations. Understanding these differences can aid in the development of strategies to enhance bystander CPR and improve overall patient outcomes., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Introduction: Out-of-hospital cardiac arrest (OHCA) is a leading cause of death. The 2010 American Heart Association Emergency Cardiovascular Care (ECC) Guidelines recognize emergency dispatch as an integral component of emergency medical service response to OHCA and call for all dispatchers to be trained to provide telephone cardiopulmonary resuscitation (T-CPR) pre-arrival instructions. To begin to measure and improve this critical intervention, this study describes a nationwide survey of public safety answering points (PSAPs) focusing on the current practices and resources available to provide T-CPR to callers with the overall goal of improving survival from OHCA., Methods: We conducted this survey in 2010, identifying 5,686 PSAPs; 3,555 had valid e-mail addresses and were contacted. Each received a preliminary e-mail announcing the survey, an e-mail with a link to the survey, and up to three follow-up e-mails for non-responders. The survey contained 23 primary questions with sub-questions depending on the response selected., Results: Of the 5,686 identified PSAPs in the United States, 3,555 (63%) received the survey, with 1,924/3,555 (54%) responding. Nearly all were public agencies (n=1,888, 98%). Eight hundred seventy-eight (46%) responding agencies reported that they provide no instructions for medical emergencies, and 273 (14%) reported that they are unable to transfer callers to another facility to provide T-CPR. Of the 1,924 respondents, 975 (51%) reported that they provide pre-arrival instructions for OHCA: 67 (3%) provide compression-only CPR instructions, 699 (36%) reported traditional CPR instructions (chest compressions with rescue breathing), 166 (9%) reported some other instructions incorporating ventilations and compressions, and 92 (5%) did not specify the type of instructions provided. A validation follow up showed no substantial difference in the provision of instructions for OHCA by non-responders to the survey., Conclusion: This is the first large-scale, nationwide assessment of the practices of PSAPs in the United States regarding T-CPR for OHCA. These data showing that nearly half of the nation's PSAPs do not provide T-CPR for OHCA, and very few PSAPs provide compression-only instructions, suggest that there is significant potential to improve the implementation of this critical link in the chain of survival for OHCA.