Search PubMed⌕ Search

Biomedical subjects

E R Gonzalez

Publications and source records attributed to E R Gonzalez.

At least 37 records · Page 2Linked to original sources
PubMed1993

Pharmacologic controversies in CPR.

Since the 1985 Emergency Cardiac Care Conference, numerous controversies about the pharmacology of CPR have arisen (eg, questions about the pharmacokinetics and pharmacodynamics of drugs during CPR, the optimal vehicle for delivery of medications, and the dose of atropine in brady-asystolic cardiac arrest). This article has three objectives: 1) to critically explore these controversies, 2) to provide recommendations for clinical practice, and 3) to identify areas for future study. The ideal route is one which combines rapid access with quick delivery of drug to the central circulation. Because of hemodynamic changes during CPR, administration of drugs into the central circulation is preferable when compared with peripheral venous injection. Whenever drugs are administered from a peripheral i.v. site, the extremity should be elevated, and a 20-mL bolus of i.v. fluid should be given to facilitate access of the agent to the central circulation. If there is a delay in obtaining venous access, epinephrine, lidocaine, and atropine may be administered through the endotracheal tube at 2.5 times the i.v. dose. When administering these drugs through the endotracheal tube, dilute the drug in 10 mL of saline or water and inject it through a long catheter beyond the tip of the endotracheal tube. Dextrose 5% water is the primary vehicle for drug delivery during CPR. However, the administration of glucose during CPR is controversial because of the potentially detrimental effects of hyperglycemia on neuronal function during periods of ischemia. Data are inconclusive regarding the effects of glucose levels on neurologic outcome following resuscitation. Hyperglycemia may be a marker for prolonged resuscitation with subsequent impairment in insulin release.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Evaluation of the Vision Theophylline assays in the emergency department setting.

STUDY OBJECTIVES: To determine whether the use of fingerstick blood samples or venipuncture blood samples affect the accuracy and the precision of the Vision Theophylline I assay and the Vision Theophylline II assay in the emergency department setting. DESIGN: Prospective clinical trial. SETTING: ED in a university teaching hospital. SUBJECTS/INTERVENTIONS: Simultaneous fingerstick and venipuncture blood samples were obtained from adult patients who required baseline theophylline levels in the ED. MEASUREMENTS: The Vision system was used in the ED to measure theophylline concentrations from fingerstick and venipuncture samples. Vision samples were drawn and analyzed by one of three pharmacists rounding within the ED between March and October 1990. These pharmacists were instructed by laboratory personnel concerning pertinent operating procedures. The vision Theophylline I and Theophylline II assays are enzyme-inhibitor immunoassays contained within a multi-chamber test packet. The high-performance liquid chromatography (HPLC) theophylline assay was used as the reference method. MAIN RESULTS: Linear regression of theophylline concentrations determined by the Vision Theophylline I assay versus HPLC revealed a significant correlation for fingerstick samples (r = .9440; P less than .05) and for venipuncture samples (r = .9750; P less than .05). The accuracy values for Vision Theophylline I assay venipuncture and fingerstick samples versus HPLC were -0.63 +/- 1.2 mg/l and 0.22 +/- 1.8 mg/L, respectively. The precision for Vision Theophylline I assay venipuncture and fingerstick samples versus HPLC were 0.27 and 0.38, respectively. Linear regression of theophylline concentrations determined by the Vision Theophylline II assay versus HPLC revealed a significant correlation for fingerstick samples (r = .9804; P less than .05) and for venipuncture samples (r = .9875; P less than .05). Accuracy values for Vision Theophylline II fingerstick and venipuncture samples versus HPLC were -0.53 +/- 1.4 mg/L and -0.65 +/- 1.3 mg/L, respectively. Precision values for Vision Theophylline II fingerstick and venipuncture samples versus HPLC were 0.34 and 0.29, respectively. CONCLUSION: There is a strong correlation between theophylline concentrations measured by Vision Theophylline assay versus HPLC, regardless of whether the Vision Theophylline assay is performed on a fingerstick or venipuncture sample. Vision fingerstick samples were more accurate than Vision venipuncture samples for both Vision Theophylline I and II assays. Theophylline concentrations measured by the Vision system using venipuncture samples were slightly more precise than those using fingerstick samples when compared with HPLC analysis. These differences in accuracy and precision were not clinically relevant.

Blood Specimen Collection↗
PubMed1992

Hospital delays and problems with thrombolytic administration in patients receiving thrombolytic therapy: a multicenter prospective assessment. Virginia Thrombolytic Study Group.

STUDY OBJECTIVES: To assess the timing of key decisions and clinical events in the treatment of acute myocardial infarction with thrombolytic therapy. DESIGN: Prospective study of emergency department patients. SETTING: EDs in 11 urban and two rural hospitals. TYPES OF PARTICIPANTS: Patients with presumed acute myocardial infarction for whom a decision was made in the ED to administer thrombolytic therapy. MEASUREMENTS AND MAIN RESULTS: Statistical analyses included determination of frequency of response, cross tabulation analysis, and Wilcoxon rank sum tests. In 210 thrombolytic-treated patients (mean age, 57 +/- 14.1 years), a median time of 155 minutes elapsed between pain onset and therapy; 67% of the delay was pre-ED arrival. The median time between ED arrival and the initial ECG was six minutes. The median time required for physicians to make a treatment decision was 20 minutes, followed by another median time of 20 minutes for staff to begin drug infusion. The median total hospital (door-to-needle) time was 50 minutes. Significantly shorter delays occurred in urban, teaching, and high-volume hospitals; when thrombolytics were stocked and/or started in the ED; and when emergency physicians treated without involving private attending physicians. Although 95% of patients received tissue plasminogen activator, six patients treated with anisoylated plasminogen-streptokinase activator complex experienced a significantly faster door-to-needle time (P less than .05). CONCLUSION: Thrombolytics should be stocked and started in the ED. Emergency physicians should generally make the decision to administer thrombolytic therapy with reference to accepted protocols without awaiting an ED consultation from either private attendings or cardiologists.

Adult↗
PubMed1992

Adjunctive medications in patients receiving thrombolytic therapy: a multicenter prospective assessment. The Virginia Multicenter Thrombolytic Study Group.

OBJECTIVE: To describe the use of adjunctive therapies in patients with acute myocardial infarction receiving thrombolytic agents. DESIGN: Data were collected prospectively by the study-site investigator or the emergency department physician caring for the patient. Study participation did not influence thrombolytic regimen selection or the adjunctive therapies ordered. SETTING: Thirteen Virginia hospitals representing a cross-section of hospitals in the state. Eleven are urban medical centers; four have graduate medical education programs. PARTICIPANTS: Patients were included in the study if the decision to administer thrombolytic therapy was made in the emergency department. MAIN OUTCOME MEASURES: Concomitant medications administered during the first six hours after initiation of thrombolytic therapy. RESULTS: Two hundred ten patients (aged 57 +/- 14.1 y) were evaluated. Ninety-five percent of these patients were treated with tissue plasminogen activator, 3 percent received anisoylated plasminogen streptokinase activator complex, and 2 percent received streptokinase. Ninety-one percent of the patients also received heparin, the most commonly used adjunctive medication; 77 percent concomitantly received lidocaine; 62 percent received aspirin; and only 19 percent received a beta-blocker. CONCLUSIONS: Our data provide a reference point for future studies to determine factors that influence the selection of adjunctive agents for treating patients with acute myocardial infarction receiving thrombolytics.

Adrenergic beta-Antagonists↗
PubMed1992

Assessment of the drug interaction between intravenous nitroglycerin and heparin.

OBJECTIVE: To assess whether a clinically significant interaction occurs between heparin and nitroglycerin (NTG). METHODOLOGY: Activated partial thromboplastin time (APTT) was measured in patients with unstable angina who were stabilized on intravenous NTG and heparin just prior to weaning the NTG infusion, and one and four hours after stopping the NTG. RESULTS: In 22 heparin-treated patients (20 men, 2 women; aged 56.7 +/- 10 years; weight 79.5 +/- 15 kg), the APTT ratio was inversely related to the dose of NTG (slope = -0.003; p < 0.05). However, there were no significant differences between the APTT values measured before and after discontinuation of NTG (p = 0.8511). CONCLUSIONS: Our study demonstrates a clinically insignificant interaction between NTG and heparin at NTG doses commonly used in patients.

Aged↗
PubMed1991

Dose-response evaluation of oral labetalol in patients presenting to the emergency department with accelerated hypertension.

STUDY OBJECTIVE: Dose-response evaluation of oral labetalol (100, 200, or 300 mg) on heart rate and systemic blood pressure in emergency department patients with hypertensive urgency (diastolic blood pressure, 110 to 140 mm Hg, and no end-organ evidence of hypertensive emergency). METHODS: This acute-treatment, dose-ranging study used a randomized, double-blind, parallel design. Patients with supine diastolic blood pressure of 110 to 140 mm Hg after 30 minutes of bedrest received an oral dose of labetalol. Supine blood pressure and heart rate were measured manually and recorded hourly for four hours after dose. Diastolic blood pressure of 100 mm Hg or less or a 30-mm Hg reduction in diastolic blood pressure was considered a treatment success. RESULTS: Two hundred fifty-five patients were evaluated for inclusion, and 36 patients (19 women and 17 men; mean age, 44 years; age range, 23 to 67 years) were studied. The most frequent reason for exclusion was a spontaneous decrease in diastolic blood pressure to less than 110 mm Hg (31%) with bedrest. There were 12 patients in each treatment group. Compared with baseline, the 100-mg dose significantly (P less than .05) reduced heart rate at three and four hours after dose, and the 300-mg dose significantly (P less than .05) reduced heart rate at one, two, and three hours after dose; the 200-mg dose did not significantly affect heart rate. All doses produced a significant decrease in systolic and diastolic blood pressures at one, two, three, and four hours after dose compared with baseline. There were no statistically significant differences between treatment groups with regard to systolic or diastolic blood pressure or heart rate at baseline or one, two, three, or four hours after dose. At two hours after dose, diastolic blood pressure control was observed in 75%, 58%, and 67% of patients receiving 100, 200, and 300 mg, respectively (P = .903). At four hours after dose, diastolic blood pressure control was observed in 50%, 64%, and 67% of patients receiving 100, 200, and 300 mg, respectively (P = .755). A comparison of treatment success rates between the two time periods showed a waning of response with the 100-mg dose of labetalol at hour 4 compared with hour 2 (P less than .05). No adverse effects were observed. CONCLUSION: Labetalol provides safe and effective treatment for hypertensive urgencies when administered orally in doses of 100 to 300 mg.

Administration, Oral↗
PubMed1991

Intermittent injection vs patient-controlled analgesia for sickle cell crisis pain. Comparison in patients in the emergency department.

BACKGROUND: --The purpose of this study is a prospective assessment of morphine sulfate administration by intermittent intravenous (IV) injections (Int-IV) vs patient-controlled analgesia (PCA) in patients in the emergency department (ED) with sickle cell crisis pain. METHODS: --Patients were at bed rest and received intravenous hydration. Linear analog scale for pain intensity and verbal pain scale, level of alertness, and vital signs were assessed prior to therapy, every 60 minutes thereafter, and at the time of discharge from the ED. Patients were randomized to Int-IV or PCA. During phase 1, patients in the Int-IV group received morphine sulfate 4 mg IV every 30 to 60 minutes as necessary for a linear analog scale for pain intensity greater than 50 mm. The patients in the PCA group received morphine sulfate 2 mg bolus then 1.0 mg with a 6-minute lockout. During phase 2, patients in the Int-IV group received morphine sulfate 8 mg IV every 30 to 60 minutes as necessary for a linear analog scale for pain intensity greater than 50 mm. The patients in the PCA group received morphine sulfate 5 mg bolus then 2.7 mg with a 10-minute lockout. Data were analyzed by unpaired t test, general linear modeling, Mann-Whitney U test, and chi 2 test. RESULTS: --During phase 1, 10 patients (28.3 +/- 7.3 years) received Int-IV and 10 patients (33.9 +/- 12.5 years) received PCA. Treatment groups did not differ significantly regarding duration of pain, amount of morphine administered, linear analog scale for pain intensity, verbal pain scale, level of alertness, or vital signs except for a significantly lower final respiratory rate with Int-IV. In phase 2, 12 patients (28.4 +/- 5.6 years) received Int-IV and 13 patients (26.8 +/- 8.1 years) received PCA. The PCA groups had a significantly shorter elapsed time between onset of pain and treatment (7.3 +/- 6.5 hours) when compared with the Int-IV group (18 +/- 16.9 hours). Treatment groups did not differ significantly with respect to total amount of morphine administered, linear analog scale for pain intensity, verbal pain scale, vital signs, or level of alertness. The PCA group had a significant reduction in length of stay in the ED during phase 2 when compared with phase 1. The ED discharge rate and the incidence of side effects did not differ significantly between groups. CONCLUSION: --At both the low- and high-dose regimens, PCA is equally safe and effective and may be used in place of Int-IV administration of morphine in the ED treatment of sickle cell crisis pain.

Adult↗
PubMed1990

Time-motion study of intravenous ranitidine admixtures.

This study determined the total preparation time, cost, and contamination rate associated with preparing 50-mL admixtures of ranitidine 50 mg from each of the following commercial source vials: 50 mg/2 mL unit-dose vial (treatment A), 50 mg/2 mL 10 mL multidose vial (treatment B), and 50 mg/2 mL 40 mL multidose vial (treatment C). The study consisted of two separate phases: phase I extemporaneous compounding and phase II batch manufacturing. Twelve technicians prepared ten admixtures from each source vial during each phase. All admixtures were tested for sterility; bacterial contamination was not observed. Multidose vials saved approximately $197 per 200 admixtures. Drug and personnel costs were reduced when batch manufacturing with 40-mL multidose vials was compared with extemporaneous compounding with unit-dose vials. Our study showed that multidose vials decreased the total preparation time and cost for making ranitidine admixtures during both extemporaneous compounding and batch manufacturing by reducing setup time, preparation time, and drug procurement cost.

Drug Compounding↗
PubMed1990

Gastroesophageal reflux and respiratory symptoms: is there an association? Proposed mechanisms and treatment.

Gastroesophageal reflux (GER) is a dysfunction of the distal esophagus causing movement of stomach contents into the esophagus. Patients may develop heartburn, regurgitation, dysphagia, odynophagia, and hemorrhage. Respiratory symptoms occur in 10-60 percent of patients with GER or hiatal hernia. Although there is evidence associating pulmonary symptoms and GER, causality has not been proven. The appropriate use of antireflux therapy or surgery to treat GER may consequently alleviate respiratory symptoms.

Bronchodilator Agents↗
PubMed1990

Pathophysiologic changes in the critically ill patient: risk factors for ulceration and altered drug metabolism.

Virtually all patients who are under the physiologic stress of an intensive care unit (ICU) are vulnerable to stress-related mucosal damage and ulceration. Although clinically significant hemorrhage from stress ulceration occurs in only 5-20 percent of patients in the ICU, the associated mortality is greater than 50 percent. The pathophysiologic mechanisms of stress ulcer are not well understood; however, a number of risk factors such as intraluminal gastric acidity and mucosal ischemia have been implicated. To prevent the development of stress ulcers and subsequent complications, it is important to identify and correct these underlying risk factors. Improving mucosal blood flow (i.e., fluid resuscitation and low-dose dopamine) and providing adequate nutritional support are invaluable adjuncts in minimizing the risk of stress ulcer formation. The use of pharmacologic prophylaxis controls the gastric acidity and prevents the formation of stress ulcers. The potential for drug-induced adverse effects and drug-drug interactions are of particular concern in the care of critically ill patients. Multiple organ system dysfunction or failure, malnutrition, fluid and electrolyte abnormalities, as well as the use of multiple pharmacologic agents predispose these patients to alterations in drug pharmacokinetics, drug-induced adverse effects and drug-drug interactions. These changes may alter the pharmacodynamic response to therapy and must be considered when designing drug dosage regimens for critically ill patients.

Critical Care↗
PubMed1989

Computer-assisted optimization of aminophylline therapy in the emergency department.

The emergency department (ED) is a unique setting for pharmacokinetic-guided drug administration because of the need to rapidly optimize therapy. We compared outcomes in patients receiving intravenous aminophylline according to population-based ED guidelines (group 1) or Bayesian-derived pharmacokinetic estimates (group 2), we determined predictors for admission or discharge in our study group, and we assessed the ability of a Bayesian pharmacokinetic model to estimate theophylline requirements in the ED. The study population was composed of 82 patients (42 males, 40 females) with a mean age of 43 +/- 15.5 years. Fifteen patients were excluded because of protocol violations. Of the 67 cases studied, 30 were assigned to group 1, and 37 were assigned to group 2. Patient demographics, baseline theophylline concentration, and theophylline loading dose did not differ significantly between treatment groups. The aminophylline maintenance infusion was significantly (P less than .001) lower in group 1 (0.4 +/- 0.2 mg/kg/h) than in group 2 (0.6 +/- 0.2 mg/kg/h). Serum theophylline concentrations at one hour post-loading-dose did not differ significantly between treatment groups; however, significant differences were observed at two hours post-load (P less than .002) and four hours post-load (P less than .001). Baseline peak flow rate (PFR) was significantly (P less than .03) higher in group 1 (170 +/- 85 L/min) than in group 2 (132 +/- 62 L/min), but did not differ significantly at any other times throughout the study. The PFR one hour post-load (PFR-1) was the strongest (P less than .003) predictor of outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

The effect of applied chest compression force on systemic arterial pressure and end-tidal carbon dioxide concentration during CPR in human beings.

Twelve adult (nine men and three women) cardiac arrest patients were studied as they received CPR by a computerized Thumper to determine the influence of the applied chest compression force on blood flow (as assessed by the end-tidal carbon dioxide concentration) and arterial pressure. At the end of a resuscitation when the decision was made by the senior physician to cease resuscitative efforts, the applied force on the CPR Thumper was decreased from 140 to 0 pound-force (lbf) in 20-lbf increments at 30-second intervals. Radial artery cutdown blood pressure and end-tidal carbon dioxide (ETCO2) were recorded continuously. Arterial systolic blood pressure was linearly related (r = .59, P less than .0001) to applied force (systolic blood pressure, 31 +/- 6 mm Hg at 20 lbf to 60 +/- 7 mm Hg at 140 lbf). ETCO2 (r = .42, P less than .0001) was also linearly related to applied force (ETCO2, 0.7 +/- 0.1% at 20 lbf to 1.5 +/- 0.2% at 140 lbf). Diastolic pressure did not change significantly with change in applied force (17 +/- 2 mm Hg from 20 to 140 lbf). Our findings indicate that higher compression force than that currently recommended may improve arterial systolic pressure and flow in human beings receiving closed-chest compression during CPR.

Blood Pressure↗
PubMed1989

Dose-dependent vasopressor response to epinephrine during CPR in human beings.

The optimal dose of epinephrine during CPR in human beings is unknown. We studied ten prehospital cardiac arrest patients (six men and four women; mean age, 54 +/- 5 years) to determine the vasopressor response and change in the end-tidal carbon dioxide concentration (PetCO2) after incremental (1-, 3-, and 5-mg) doses of IV epinephrine given five minutes apart during closed-chest CPR. All patients were in ventricular fibrillation on arrival of the paramedics and did not respond to standard advanced cardiac life support. CPR was performed with a computerized Thumper; all patients were intubated and ventilated at 12 times a minute at an FiO2 of 0.8. Radial artery pressure was measured with a 20 angiocath inserted by radial artery cutdown. Paramedic response time was 4.3 +/- 0.5 minutes; elapsed time to emergency department arrival was 40.0 +/- 9.5 minutes. Initial blood gases were paO2, 241 +/- 50 mm Hg; pH, 7.23 +/- 0.08; paCO2, 27 +/- 5 mm Hg; and HCO3, 11 +/- 2 mEq/L. Baseline systolic and diastolic blood pressures were 47 +/- 5 mm Hg and 18 +/- 2 mm Hg, respectively. Systolic blood pressure was directly related to the dose of epinephrine (P less than .0001), rising to 69 +/- 7 mm Hg, 74 +/- 8 mm Hg, and 85 +/- 8 mm Hg after 1-, 3-, and 5-mg doses of epinephrine, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1989

Reducing the risk of aspiration pneumonitis.

Regurgitation of gastric contents with subsequent aspiration into the lungs contributes significantly to morbidity and mortality in surgical and nonsurgical patients. The consequences of aspiration pneumonitis depend on the volume and the acidity of the aspirate, and the presence of particulate and bacteria in the aspirate. The occurrence of aspiration pneumonitis may be prevented by correction of risk factors, careful monitoring, and appropriate airway management. The goal of aspiration pneumonitis prophylaxis is to minimize pulmonary complications by controlling risk factors for gastric regurgitation, which include gastric pH less than or equal to 2.5, gastric volume greater than 25 mL, lower esophageal sphincter incompetence, and delayed peristalsis. Prophylactic techniques include nasogastric decompression, acid neutralization, acid suppression, and increased gastric peristalsis. The ability of drugs to alter risk factors does not guarantee that aspiration will not occur, but it does reduce the likelihood of secondary respiratory complications. The ideal prophylactic agent should consistently reduce all risk factors, produce a prompt and sustained response, and possess few adverse effects and drug interactions.

Humans↗
PubMed1989

Single-dose intravenous H2 blocker prophylaxis against aspiration pneumonitis: assessment of drug concentration in gastric aspirate.

This placebo-controlled trial compared the effects of preoperative, intravenous cimetidine (300 mg) or ranitidine (50 mg) on gastric pH and gastric volume in 31 adult patients requiring general anesthesia. The elapsed time from drug administration to initial gastric sampling did not differ significantly between ranitidine (45 minutes), cimetidine (48 minutes), or placebo (52 minutes) treated patients. Ranitidine, but not cimetidine, significantly (P = 0.02) increased gastric pH when compared with placebo. Gastric pH correlated (r = 0.7, P = 0.01) with cimetidine concentration in gastric fluid at induction. Gastric pH was directly proportional to ranitidine concentration in gastric fluid at induction, but the correlation was weak (r = 0.54, P = 0.1). The H2 blockers did not significantly alter gastric volume when compared with placebo. The number of patients with gastric pH less than = 2.5 and gastric volume = greater than 25 ml did not differ significantly between cimetidine (8%), ranitidine (10%), and placebo (22%). No clinical evidence of aspiration pneumonitis was found in our study patients.

Adult↗
PubMed1988

Cost-effectiveness of defibrillation by emergency medical technicians.

Effective emergency systems using emergency medical technicians (EMTs) trained to defibrillate or paramedics can save more lives from out-of-hospital cardiac arrest due to ventricular fibrillation than can emergency systems staffed with basic EMTs who cannot defibrillate. This article focuses on the cost-effectiveness of systems staffed with each type of EMT. Data were collected from all 50 states and from the District of Columbia to determine the number of hours and estimated cost of initial training for the three types of EMTs in the United States in 1986. The median initial training hours for basic EMTs, EMTs trained in defibrillation, and paramedics were 110, 129, and 700, respectively. Median costs for initial training at each EMT level were +123, +150, and +1580/student. According to published survival data for emergency medical systems staffed with EMTs at each level, the total initial training personnel and equipment cost per life saved from ventricular fibrillation was +7687, +2126, and +2289 for systems staffed by the respective EMTs. The initial cost per life saved from ventricular fibrillation is more than three times greater in systems staffed by basic EMTs than in systems staffed by EMTs trained in defibrillation or paramedics. From a medical and a cost-effective standpoint, all communities served by basic EMTs should consider upgrading them to at least the defibrillation-trained EMT level.

Allied Health Personnel↗