PubMed Health⌕ Search

Biomedical subjects

Patrick R Hunziker

Publications and source records attributed to Patrick R Hunziker.

8 recordsLinked to original sources
PubMed2006

Incidence, risk factors, and outcome of aspiration pneumonitis in ICU overdose patients.

OBJECTIVE: To assess the incidence and outcome of clinically significant aspiration pneumonitis in intensive care unit (ICU) overdose patients and to identify its predisposing factors. DESIGN: Retrospective cohort study. SETTING: Medical ICU of an academic tertiary care hospital. PATIENTS: A total of 273 consecutive overdose admissions. MEASUREMENTS AND RESULTS: Clinically significant aspiration pneumonitis was defined as the occurrence of respiratory dysfunction in a patient with a localised infiltrate on chest X-ray within 72 h of admission. In our cohort we identified 47 patients (17%) with aspiration pneumonitis. Importantly, aspiration pneumonitis was associated with a higher incidence of cardiac arrest (6.4 vs 0.9%; p = 0.037) and an increased duration of both ICU stay and overall hospital stay [respectively: median 1 (interquartile range 1-3) vs 1 (1-2), p = 0.025; and median 2 (1-7) vs 1 (1-3), p < 0.001]. In multivariate logistic regression analysis, Glasgow Coma Scale (GCS) score [odds ratio (OR) for each point of GCS 0.8; 95% confidence interval (CI) 0.7-0.9; p = 0.001], ingestion of opiates (OR 4.5; 95% CI 1.7-11.6; p = 0.002), and white blood cell count (WBC) (OR for each increase in WBC of 10(9)/l 1.05; 95% CI 1.0-1.19; p = 0.049) were identified as independent risk factors. CONCLUSIONS: Clinically relevant aspiration pneumonitis is a frequent complication in overdose patients admitted to the ICU. Moreover, aspiration pneumonitis is associated with a higher incidence of cardiac arrest and increased ICU and total in-hospital stay.

Adult↗
PubMed2005

Echocardiographic quantification of atherosclerosis leads to cost-effective treatment with statins.

OBJECTIVE: Use of statins in prevention of atherosclerosis is effective but expensive. Patient selection gains wider public attention as medication costs in the US and Europe augment by 8% to 10% per year. We examined different clinical risk stratification strategies, particularly focusing on echocardiographic atherosclerosis quantification, for their impact on event reduction and cost-effectiveness in statin treatment. METHODS AND RESULTS: In a prospective, consecutive cohort of 336 patients referred to non-invasive cardiac examination, risk stratification was done by various combinations of risk factors and noninvasive atherosclerosis quantification. Atherosclerotic burden was determined through measuring "aortic elastance" by transthoracic echocardiogram, a validated non-invasive method. Cardiovascular events were recorded at a mean follow-up of one year. Echocardiographically determined atherosclerosis severity and event history, especially in combination, yielded the best selection strategies for statin treatment over a broad range of predetermined funding or required event reductions, surpassing conventional cardiovascular risk factors. From 26.8 statin-preventable events/1000 patients/year (assuming all patients treated), the best selection strategies could avoid: 24 with 66% of the cost for statin treatment (atherosclerosis and age criteria), 20.1 with <50% of the budget, 12.2 with <30% of the budget or 9.6 with <15% of the budget (using combinations of atherosclerosis and prior events), while conventional strategies without echo quantification of atherosclerosis were inferior. CONCLUSION: Non-invasive echocardiographic quantification of atherosclerosis improves efficiency and cost-effectiveness in statin treatment.

Aged↗
PubMed2005

Investigating native coronary artery endothelium in situ and in cell culture by scanning force microscopy.

The purpose of our studies is to better understand the morphology and functioning of the arteries and their changes in pathogenesis. The most frequently used imaging techniques are intravascular ultrasound, magnetic resonance imaging, and optical coherence tomography. These methods do not image cell-level structural details and only provide biomechanical properties indirectly. We present a new protocol for imaging the endothelial surface and measuring elastic properties of vascular tissue by scanning force microscopy. Full-thickness sections of native pig coronary arteries were prepared. In addition, cultured human umbilical vein endothelial cells were studied as an in vitro model system and for comparison. We encountered a variety of difficulties mostly due to the softness of vascular tissue which required significant adaptations of standard equipment: (i) a new specimen holder designed to stably immobilize the coronary arteries; (ii) a phase-contrast microscope incorporated for assessing the status of the cultured endothelial cells and positioning the scanning force microscope (SFM) tip at a site of interest; and (iii) a continuous exchange of the culture medium at 37 degrees C to assure viability of the cells in the SFM over extended times. We were thus able to investigate both fresh arterial tissue and living endothelial cells in a near-physiological environment. We present initial SFM images of vascular tissue at a spatial resolution similar to scanning electron microscopy, but which also provide a closer view of the bona fide structure of native tissue. Novel morphological features such as distinct granular particles were observed. Moreover, we report initial measurements of vascular tissue surface stiffness, obtained by indentation-type SFM.

Animals↗
PubMed2005

Performance of first responders in simulated cardiac arrests.

OBJECTIVE: Survival of in-hospital cardiac arrests depends more on first responders than on cardiac arrest teams. The objective of this study was to determine the adherence to algorithms of cardiopulmonary resuscitation of first responders in simulated cardiac arrests in intensive care. A second objective was to assess the effect of the early vs. late availability of a physician on the performance of nurse-based teams acting as first responders. DESIGN: Prospective study. SETTING: Patient simulator in a tertiary level intensive care unit. PARTICIPANTS: A total of 20 teams consisting of three registered nurses and one resident each. INTERVENTIONS: A simulated witnessed cardiac arrest due to ventricular fibrillation occurred in the presence of one nurse while the remaining two nurses could be called to help. Depending on the time of the residents' arrival, teams were classified as "early" (median arrival 50 secs after the onset of the arrest) or "late" (median arrival 150 secs after the onset of the arrest). MEASUREMENTS AND MAIN RESULTS: In all teams, the recognition of the arrest and the calling for help occurred in a timely fashion. However, a median of 85 secs (interquartile range [IQ], 130 secs) elapsed until the start of cardiac massage and 100 secs (IQ, 45 secs) to the first defibrillation. Once commenced, cardiac massage and mask ventilation were carried out during 61% (IQ, 33%) and 77% (IQ, 23%) of the possible time only. Delays and interruptions were generally not recalled by the participants. Compared with teams with late arriving residents, teams with early arriving residents administered more countershocks: 4.5 (IQ, 2) vs. 3.5 (IQ, 1.5; p = .026). CONCLUSIONS: First responders in intensive care often failed to build a team structure that ensured timely, effective, monitored, and ongoing team activity. The early availability of a physician increased the number of countershocks administered. Self-reporting is unsuitable to reliably assess the quality of cardiopulmonary resuscitation.

Aged↗
PubMed2004

Human factors affect the quality of cardiopulmonary resuscitation in simulated cardiac arrests.

AIM: Cardiopulmonary resuscitation is a team endeavour. There are only limited data on whether team performance during cardiopulmonary resuscitation is influenced by behavioural issues. The aim of the study was to determine whether and how human factors affect the quality of cardiopulmonary resuscitation. METHODS: 16 teams, each consisting of three health-care workers, were studied in a patient simulator. A scenario of witnessed cardiac arrest due to ventricular fibrillation was used. Ventricular fibrillation could be converted into sinus rhythm by two countershocks administered during the first 2 min or by two countershocks administered during the first 5 min provided that uninterrupted basic life support was started in under 60 s. Teams were rated to be successful if ventricular fibrillation was converted into sinus rhythm. Behavioural rating included leadership, task distribution, information transfer, and conflicts. RESULTS: Only six out of 16 teams were successful. Compared with successful teams, teams that failed exhibited significantly less leadership behaviour (P=0.033) and explicit task distribution (P=0.035). All teams shared among them sufficient theoretical knowledge to successfully treat the simulated cardiac arrest. CONCLUSIONS: In a scenario of simulated witnessed cardiac arrest almost two thirds of teams composed of qualified health-care workers failed to provide basic life support and/or defibrillation within an appropriate time window. Absence of leadership behaviour and absence of explicit task distribution were associated with poor team performance. Failure to translate theoretical knowledge into effective team activity appears to be a major problem.

Cardiopulmonary Resuscitation↗
PubMed2002

Bedside quantification of atherosclerosis severity for cardiovascular risk stratification: a prospective cohort study.

OBJECTIVES: We sought to assess the ability of a new noninvasive method to quantify atherosclerosis severity and to examine its power to predict cardiovascular events. BACKGROUND: Drug prevention of cardiovascular events is effective but costly, leading to a debate about who should receive this treatment. Patient selection is often based on surrogate markers, but quantification of atherosclerosis severity is desirable. METHODS: Atherosclerosis severity was quantified by determination of specific aortic wall elastance in transthoracic echocardiography, applying the biomechanics of pulse wave propagation. After validating the method in 52 patients by measuring aortic plaque burden in transesophageal echo directly, another 336 patients were prospectively studied by monitoring atherosclerotic events at one year and comparing the results with conventional risk stratification. RESULTS: Specific aortic elastance was well correlated with plaque burden (p < 0.0001) and largely independent of confounding variables. Specific aortic elastance predicted the primary end point of "atherosclerotic death, myocardial infarction or stroke" at one year (p < 0.0002). Event rate at one year in the lowest specific elastance tertile was 1.8% (CI 0.0% to 4.3%), in the middle tertile 5.4% (CI 1.1% to 9.7%) and in the highest tertile 12.7% (CI 6.3% to 19%). Secondary end points supported these findings. Stepwise multivariate analysis identified specific aortic elastance, prior atherosclerotic events and left ventricular ejection fraction as independent risk predictors. Specific elastance was of incremental value to clinically identified variables. CONCLUSIONS: Bedside measurement of specific aortic elastance allows assessment of atherosclerosis severity. It predicts the risk for future atherosclerotic events beyond conventional risk factors, promising better targeting of pharmacologic prevention and improved cost effectiveness.

Adult↗
PubMed2002

Four-dimensional wavelet compression of arbitrarily sized echocardiographic data.

Wavelet-based methods have become most popular for the compression of two-dimensional medical images and sequences. The standard implementations consider data sizes that are powers of two. There is also a large body of literature treating issues such as the choice of the "optimal" wavelets and the performance comparison of competing algorithms. With the advent of telemedicine, there is a strong incentive to extend these techniques to higher dimensional data such as dynamic three-dimensional (3-D) echocardiography [four-dimensional (4-D) datasets]. One of the practical difficulties is that the size of this data is often not a multiple of a power of two, which can lead to increased computational complexity and impaired compression power. Our contribution in this paper is to present a genuine 4-D extension of the well-known zerotree algorithm for arbitrarily sized data. The key component of our method is a one-dimensional wavelet algorithm that can handle arbitrarily sized input signals. The method uses a pair of symmetric/antisymmetric wavelets (10/6) together with some appropriate midpoint symmetry boundary conditions that reduce border artifacts. The zerotree structure is also adapted so that it can accommodate noneven data splitting. We have applied our method to the compression of real 3-D dynamic sequences from clinical cardiac ultrasound examinations. Our new algorithm compares very favorably with other more ad hoc adaptations (image extension and tiling) of the standard powers-of-two methods, in terms of both compression performance and computational cost. It is vastly superior to slice-by-slice wavelet encoding. This was seen not only in numerical image quality parameters but also in expert ratings, where significant improvement using the new approach could be documented. Our validation experiments show that one can safely compress 4-D data sets at ratios of 128:1 without compromising the diagnostic value of the images. We also display some more extreme compression results at ratios of 2000:1 where some key diagnostically relevant key features are preserved.

Algorithms↗