Horacio Hojman

Continuous cardiac output monitoring by peripheral blood pressure waveform analysis

We introduce a novel technique for continuously monitoring changes in cardiac output (CO) by mathematical analysis of a single peripheral arterial blood pressure (ABP) waveform. In contrast to all previous techniques, our technique analyzes ABP variations over time scales greater than a cardiac cycle in which wave reflections are attenuated. To validate the technique, we performed six swine experiments in which peripheral ABP waveforms and gold standard CO via an aortic flow probe were simultaneously measured over a wide physiologic range. We report an overall CO measurement error of only 15.0%.

Leadership During the Boston Marathon Bombings: A Qualitative After-Action Review.

OBJECTIVE On April 15, 2013, two improvised explosive devices (IEDs) exploded at the Boston Marathon and 264 patients were treated at 26 hospitals in the aftermath. Despite the extent of injuries sustained by victims, there was no subsequent mortality for those treated in hospitals. Leadership decisions and actions in major trauma centers were a critical factor in this response. METHODS The objective of this investigation was to describe and characterize organizational dynamics and leadership themes immediately after the bombings by utilizing a novel structured sequential qualitative approach consisting of a focus group followed by subsequent detailed interviews and combined expert analysis. RESULTS Across physician leaders representing 7 hospitals, several leadership and management themes emerged from our analysis: communications and volunteer surges, flexibility, the challenge of technology, and command versus collaboration. CONCLUSIONS Disasters provide a distinctive context in which to study the robustness and resilience of response systems. Therefore, in the aftermath of a large-scale crisis, every effort should be invested in forming a coalition and collecting critical lessons so they can be shared and incorporated into best practices and preparations. Novel communication strategies, flexible leadership structures, and improved information systems will be necessary to reduce morbidity and mortality during future events.

Adaptive Left Ventricular Ejection Time Estimation Using Multiple Peripheral Pressure Waveforms

An adaptive approach is proposed for the problem of left ventricular ejection time (LVET) estimation using peripheral pressure waveform signals. The proposed algorithm, which makes use of 2 peripheral pressure measurements, makes it possible to adaptively estimate the LVET in response to different cardiovascular physiologic states. The algorithm builds on features obtained from global and branch-specific characterization of the cardiovascular circulation as well as waveform features to dramatically improve the accuracy of LVET estimation. The performance of the proposed approach is evaluated with respect to its heart-rate-based conventional counterpart, which shows approximately 40% improvement of estimation accuracy in terms of R2 values from 0.6655 for the conventional waveform-based approach to 0.9222 for the proposed approach

Reconstruction of Central Aortic Pressure Waveform Using Adaptive Multi-Channel Identification

This paper presents an adaptive multi-channel (AMC) approach for the reconstruction of the central aortic blood pressure (BP) waveform from multiple peripheral BP measurements. In contrast to most of the previously developed single-channel methods for estimating central aortic BP waveform, the key merit of the AMC algorithm is its ability to be individualized without any prior model training or parameter tuning. Preliminary experimental evaluation of the AMC algorithm with respect to a single channel approach in a swine model shows 17.4% improvement in the waveform reconstruction accuracy in terms of RMSE (from 3.3 mmHg for the single-channel approach to 2.8 mmHg for the AMC algorithm) and the superior prediction of several key central aortic BP waveform features (from 0.1512 to 0.9109 for the ejection duration, in terms of r2 values). These results suggest that the AMC algorithm can render a very accurate reconstruction of the central aortic BP waveform from two peripheral BP measurements without any prior model training or parameter tuning

Psychodynamic Perspectives on Psychotropic Medications for Children and Adolescents

Recent trends in pediatric psychopharmacology have resulted in advances in treatment but also an overly optimistic and, at times, simplistic extension of pediatric psychopharmacology practice. Concerns about these changes in the field are discussed. The authors outline how understanding the meaning of medications to all those involved in the prescribing process can help integrate our thinking about this complex interaction with patients and their families.

Infarcted splenule—a case report

A 38-year-old woman presented with abdominal pain and left shoulder pain. A computed tomography scan was obtained, which demonstrated a rounded soft tissue density with surrounding stranding. It was interpreted as an infarcted splenule. Due to the increasing severity of the patient’s symptoms, a laparoscopic exploration was performed. Pathology demonstrated an infarcted splenule. As infarcted splenules are rare, an understanding of its pathogenesis and familiarity with the corresponding imaging findings may be helpful for its diagnosis in the patient with the appropriate clinical scenario. It is important to recognize this entity as a cause of abdominal pain that can be managed nonsurgically.

A Friend's Request for Treatment.

Although the practice guidelines of several medical organizations recommend against treating friends or relatives, they make exceptions for emergencies or the unavailability of other qualified physicians.