Kevin R. Ward

SYSTEMIC ANALGESIA AND SEDATION IN MANAGING ORTHOPEDIC EMERGENCIES

Many potent agents have become available in the emergency department for providing systemic analgesia and sedation for painful orthopedic procedures. This article details the pharmacology and principles of systemic analgesia and sedation, which will help the emergency physician provide maximal patient comfort with minimal complications during painful procedures. The use of an appropriate agent in these situations will optimize the outcome of the procedure itself and result in greater patient satisfaction.

Peripheral tissue oxygenation improves during ED treatment of acute heart failure

OBJECTIVE The objective of the study was to quantitatively characterize peripheral tissue microvascular oxygenation during emergency department (ED) treatment of acute heart failure (HF). METHODS This prospective, observational study enrolled acutely decompensated HF patients presenting to an urban ED and stable, asymptomatic HF patients evaluated in an outpatient cardiology clinic. Stable, pre-ED treatment, and post-ED treatment microvascular oxygen extraction ratios (OER(M)s) were calculated, defined as SaO(2) - StO(2)/0.8*SaO(2), where SaO(2) is pulse oximetry-derived arterial hemoglobin saturation and StO(2) is the tissue hemoglobin oxygen saturation measured with differential absorption spectroscopy. The OER(M) measurements were analyzed using repeated-measures analysis of variance. Pulse oximetry, patient demographics, HF etiology, serum B-type natriuretic peptide, and hemoglobin were measured along with a visual analogue scale to assess patient baseline characteristics and response to ED treatment (P < .05 was considered significant for all testing). RESULTS The OER(M) for the stable HF group (n = 45) was 0.65 (SE = 0.07). The pre- and posttreatment OER(M)s for the ED HF group (n = 46) were 0.92 (SE = 0.07) and 0.75 (SE = 0.06), respectively. Whereas the pretreatment ED OER(M) was higher than the stable patient OER(M) (P = .001), the posttreatment ED OER(M) was not significantly different from the stable patient measurement (P = .271). CONCLUSIONS Oxygen extraction in acute HF is significantly increased, but approaches values found in the stable HF population after ED treatment. The OER(M) may deserve closer examination as a possible goal-directed variable in the treatment of acute HF.

Effects of Perfluorocarbon Infusion in an Anesthetized Swine Decompression Model

INTRODUCTION Decompression illness (DCI) results from sudden changes in ambient pressure leading to super-saturation and bubble formation in tissues and the blood stream. Perfluorocarbon emulsions (PFC) increase both oxygen and nitrogen solubility when infused into the blood stream. This study hypothesized that PFC would increase N(2) removal as well as O(2) delivery to tissues. MATERIALS AND METHODS Juvenile swine (20 kg) were anesthetized and highly instrumented with arterial monitoring, pulmonary artery catheterization, EDAC ultrasound bubble detection, and end tidal N(2) by mass spectrometry. Blood gases were monitored in both the mixed venous and arterial circulation. Full hemodynamics were calculated using standard equations. Four groups of animals were randomized to be either sham controls or compressed and to receive either saline or PFC at 4.5 ml/kg. Animals were dry compressed to 6.8 ATA for 30 minutes of time on the bottom and then rapidly decompressed. Animals were monitored for 120 minutes after surfacing, then euthanized. RESULTS DCI was created by the dive profile but the severity was variable. Sham animals had no significant changes except that those who received PFC developed significant pulmonary hypertension and decreased cardiac output. This held true for those that also underwent DCI. Respiratory N(2) washout was not significantly different with and without PFC. However, O(2) delivery to tissues was improved with PFC and EDAC bubble count was dramatically less with PFC. CONCLUSIONS PFC decreased bubble generation but the data was confounded by a species specific pulmonary hypertensive response. Even with this as a problem O(2) delivery to tissues was enhanced by PFC. Future work with PFC in different species will help to further understand the contribution of these two mechanisms to treatment efficacy by PFC in DCI.

Impact of Congestive Heart Failure Treatment on Peripheral Microvascular Tissue Oxygenation

The authors evaluated peripheral tissue oxygenation during treatment of acutely decompensated congestive heart failure (CHF) to determine whether differences exist between patients who experienced adverse outcomes (AO), defined as death or readmission within 6 months, and patients who did not (non-AO). This prospective, observational study measured differential absorption spectroscopy-derived tissue hemoglobin oxygenation (S(t) O(2) ) in CHF patients from presentation through hospital discharge to determine whether differences between the AO and non-AO groups exist. Of 52 patients, 6 died and 27 were readmitted. In the non-AO group, S(t) O(2) increased from admission to discharge by 5.2% ( P<.01; 95% confidence interval, 1.7%-8.7%). No S(t) O(2) change occurred in the AO group (2.3%; P=.42; 95% CI, -2.2%-6.8%). Tissue oxygenation increased during inpatient treatment in CHF patients without future adverse outcomes, but was unchanged for those who later died or were readmitted. Lack of improvement may be associated with higher rates of death and readmission.

Structural Stereochemistry of Androstene Hormones Determines Interactions with Human Androgen, Estrogen, and Glucocorticoid Receptors

DHEA, 17α-AED, 17β-AED, and 17β-AET exhibit strong biological activity that has been attributed to androgenic, estrogenic, or antiglucocorticoid activity in vivo and in vitro. This study compared DHEA, 17α-AED, 17β-AED, and 17β-AET for their ability to activate the human AR, ER, and GR and determine the relative androgenicity, estrogenicity, and glucocorticoid activity. The results show that, at the receptor level, these androstene hormones are weak AR and even weaker ER activators. Direct androstene hormone activation of the human AR, ERα, and ERβ may not be essential for their biological function. Similarly, these hormones indirectly activated the human GR, only in the presence of high dexamethasone concentrations. These results underscore the major difference between androstene hormone interactions with these nuclear receptors and their biological effects.

Animal Models of Resuscitation

The ultimate goal of cardiopulmonary resuscitation (CPR) is the total reanimation of the cardiac arrest (CA) victim back to their pre-arrest status. Much of what we know and do regarding human CPR is based on animal modeling of the many components of CA and its treatment. Ideally, hypotheses regarding mechanisms of injury caused by arrest and treatments to improve outcome should first be tested in robust preclinical models of this disease followed by clinical testing. Although some aspects of the disease and treatment lend themselves to computational, cell culture, and isolated organ modeling, whole animal experimentation remains the standard for preclinical testing (1, 2, 3, 4). To this end, the proper design and use of the preclinical model is crucial to ensure that clinical trials are warranted and optimally designed for ultimate validation of the hypotheses.

Monitoring Techniques During Resuscitation

Shock is a complex entity defined traditionally as a state in which the oxygen utilization or consumption needs of tissues are not matched by sufficient delivery of oxygen. This mismatch commonly results from states of altered tissue perfusion. From this perspective, cardiopulmonary arrest represents the most extreme of shock states.

Cardiopulmonary Resuscitation in Trauma

Cardiopulmonary resuscitation (CPR) in a patient with multiple injuries involves a different approach than in a nontrauma patient. Although the basic principles are the same as dealt with in other chapters of this book, CPR in the trauma victim has to address prevention of cardiopulmonary failure from problems exclusive to the injured patient. This chapter concentrates on these issues and highlights some of the recent developments in the field.