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Biomedical subjects

E R Gonzalez

Publications and source records attributed to E R Gonzalez.

At least 73 records · Page 4Linked to original sources
PubMed1984

Cardiac vagolytic action of some neuromuscular blockers.

Cardiac vagolytic effect of four commonly used neuromuscular blockers, (viz. D-tubocurarine, decamethonium, pancuronium and gallamine) was compared in midcollicular decerebrate rats. The intravenous doses of neuromuscular blockers used (d-tubocurarine: 0.1 mg/kg; decamethonium: 2 mg/kg; pancuronium: 0.1 mg/kg; gallamine: 20 mg/kg) were sufficient to produce the paralysis of respiratory muscles. Bradycardia was induced by electrical stimulation of the vagus or by injecting dimethyl-phenyl-piperazinium (DMPP; a ganglionic stimulant). It was observed that d-tubocurarine and decamethonium were devoid of cardiac vagolytic action. On the other hand, pancuronium and gallamine inhibited significantly the bradycardia induced by electrical stimulation of the vagus or injection of DMPP; gallamine was found to have greater vagolytic action. The pressor responses to DMPP were not attenuated by pancuronium and gallamine indicating that in the dose administered, these agents did not block the ganglia. Bradycardia induced by the administration of acetylcholine in the left atrium was also attenuated by pancuronium and gallamine suggesting that the drugs produce cardiac vagolytic action by acting on the post-synaptic cholinergic receptors of the heart.

Acetylcholine↗
PubMed1984

Review of the status of intermittent positive pressure breathing therapy.

With the advent of diagnosis related groups reimbursement schedules, the cost-effectiveness of therapies needs to be assessed. The safety and efficacy of intermittent positive pressure breathing (IPPB) has been controversial. IPPB employs the dilating effects of positive-pressure ventilation to deliver aerosolized particles to small and medium-sized bronchi of patients with obstructive airways disease. IPPB is expensive to implement and maintain. The hazards of IPPB (infection, pneumothorax, decreased cardiac output), although rare, could prolong hospital stays. Except for severely ill patients with fatigued respiratory muscles, IPPB offers no advantages over the less costly and safer compressor-nebulizer or metered-dose delivery of a beta-agonist.

Asthma↗
PubMed1982

Greater splanchnic nerve activity in the rat.

The greater splanchnic nerve trunks in the rat, unlike in other experimental animals, do not join celiac plexus directly. These nerve trunks join small ganglia, the cardiac ganglia, on either side. The cardiac ganglia are located about 1 cm rostro-lateral to unpaired celiac ganglion. The greater splanchnic nerve activity immediately proximal to celiac ganglion is predominantly post-ganglionic in the rat. On the other hand, the activity of the greater splanchnic nerve proximal to the celiac ganglion is predominantly preganglionic in other experimental animals, (e.g., cat), In the rat, preganglionic sympathetic nerve activity is predominant in the segment of the greater splanchnic nerve proximal to the cardiac ganglion.

Animals↗
PubMed1981

Neurotropic action of MSH/ACTH 4-10 on neuromuscular function in hypophysectomized rats.

These studies were designed to determine whether the previously demonstrated [24] enhancement of neuromuscular function by MSH/ACTH 4-10 is due to peptide action on the neurogenic and/or myogenic elements involved. The nerve muscle unit studied incorporated the sciatic nerve and its branches, and the extensors digitorum longus and brevis in the hypophysectomized rat, in situ. Parameters investigated included muscle action potentials (MAP) and muscle contractions (MC) during 30 min of stimulation (supramaximal, 10/sec; 0.05 msec duration). Resting membrane potentials and miniature endplate potential (mepp) characteristics were investigated in situ at neuromuscular junctions in the extensor digitorum brevis. Hypophysectomy results in markedly deleterious changes in neuromuscular function which can be partially alleviated by the administration of ACTH 4-10 (0.01 microgram/kg). This dosage increases MAP and MC amplitudes and reduces fatigue. Higher dosages (1.0 microgram/kg) have a depressing effect on these parameters. The facilitatory actions of ACTH 4-10 are abolished when the muscle is stimulated directly or stimulated through the peripheral stump of the cut nerve. ACTH 4-10 increases mepp frequency (a presynaptic event) but does not affect postsynaptic characteristics as measured by the resting membrane potential. These results indicate that MSH/ACTH 4-10 influences skeletal muscle function through a neurotropic action mediated by spinal motoneurons. Changes in the central excitatory state of higher motor centers are possibly involved.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Intravenous amiodarone for ventricular arrhythmias: overview and clinical use.

Numerous pharmacological agents with varying cellular electrophysiological effects are available to treat cardiac arrhythmias. Amiodarone is predominantly a Vaughan Williams Class III agent, but also possesses electrophysiological characteristics of the other three Vaughan Williams classes (Class I and IV and minor Class II effects). Amiodarone's primary mechanism is to prolong the cardiac action potential and repolarization time leading to an increased refractory period and reduced membrane excitability. The efficacy and tolerability of intravenous (IV) amiodarone for acute treatment of recurrent and refractory ventricular tachycardia and ventricular fibrillation has been demonstrated in clinical trials. The ARREST trial, a randomized trial comparing IV amiodarone to placebo, found a significant improvement in the proportion of patients surviving to the emergency department following out-of-hospital cardiac arrest in amiodarone-treated patients. Intravenous amiodarone is an effective anti-arrhythmic agent for the acute treatment of life-threatening ventricular arrhythmias and represents an important treatment option for emergency anti-arrhythmic therapy for patients suffering from cardiac arrest.

Amiodarone↗
PubMedDate not supplied

Central resetting of baroreflex in the spontaneously hypertensive rat.

The role of central nervous system in the resetting of baroreflex was investigated in 5-month-old spontaneously hypertensive rats (SHR) of Okamoto strain. Age-matched Wistar-Kyoto (WKY) rats were used as normotensive controls. The aortic nerves, which in the rat, contain few or no chemoreceptor fibers, were stimulated electrically using a wide range of stimulus frequencies. The depressor responses (expressed as percent decrease in blood pressure as compared to its blood pressure value prior to aortic nerve stimulation) produced by these stimulations were significantly smaller in SHR than those in WKY. In another series of experiments, changes in the efferent limb of the baroreflex arc (i.e., greater splanchnic nerve activity) in response to stimulation of the baroreceptor afferents in the aortic nerve were recorded. Inhibition of the greater splanchnic nerve activity due to aortic nerve stimulation was found to be significantly smaller in SHR than in the WKY. Control sympathetic nerve activity was greater in SHR than in WKY. These results suggest that the central bulbospinal nervous system may be another site for resetting of baroreflex in hypertension.

Animals↗
PubMedDate not supplied

Cardiopulmonary resuscitation documentation: a survey of 135 medical centers.

The pharmacist is an active member of the cardiopulmonary resuscitation (CPR) team in many hospitals, dispensing medications, maintaining records, providing drug information, calculating doses, and mixing intravenous fluids. We surveyed 135 emergency department nursing directors across the country to assess the methods of and persons responsible for documentation during CPR. Ninety-five (70 percent) completed surveys were returned, showing that documentations was usually done by a nurse (81 percent), by a nurse and pharmacist (9 percent), by a pharmacist (7 percent), or by others (ward clerks, paramedics, or physicians) (3 percent). CPR flowsheets (83 percent), nurses' notes (7 percent), or other methods (10 percent) including notes on paper towels and blackboards are used to record such information in the emergency department. Most respondents were fairly confident (49 percent) or very confident (48 percent) that they could recreate the resuscitative sequence from the information recorded; 2 percent did not have confidence in the reproducibility of the data. Respondents felt that cardiac rhythms (83 percent), drugs and dosages administered (34 percent), and temporal sequence of events (33 percent) could be more accurately recorded during CPR. A majority of respondents (57 percent) felt that an automated recording system would be useful. We conclude that there appears to be considerable variability in the method of documentation of events during CPR in emergency departments throughout the country. Future efforts in emergency care should include the involvement of pharmacists in the development and implementation of a uniform database for use by field and hospital personnel during CPR.

Data Collection↗
PubMedDate not supplied

The dose of epinephrine during cardiopulmonary resuscitation in humans: what should it be?

The objective of vasopressor therapy during closed-chest cardiopulmonary resuscitation (CPR) is to augment coronary perfusion pressure so that spontaneous circulation can be reestablished. Epinephrine, an endogenous catecholamine with both alpha- and beta-adrenergic activity, is the vasopressor of choice for use during CPR. Epinephrine's potent alpha1-and alpha2-adrenergic effects improve cerebral and myocardial blood flow by preventing arterial collapse and by increasing peripheral vasoconstriction. The optimal dose of epinephrine in humans during closed-chest CPR is unknown. Studies suggest that the dose of epinephrine currently recommended during CPR may be five to ten times lower than the dose required to produce the beneficial pharmacologic effects observed in animal models of closed-chest CPR. Data from patients with prehospital cardiac arrest indicate that a 5-mg dose of epinephrine may be required to increase diastolic blood pressure above 30 mm Hg. Until additional data are available, our clinical experience suggests that all patients should receive at least one 1-mg dose of epinephrine. If the patient fails to respond, the administration of 3-5 mg of epinephrine every five minutes or the use of continuous infusions of epinephrine (0.2-0.6 mg/min) may be indicated.

Cardiopulmonary Resuscitation↗
PubMedDate not supplied

Assessment of 24-hour gastric pH measurements in trauma patients receiving intravenous famotidine by intermittent bolus versus continuous infusion administration.

OBJECTIVE: To compare the effects of intermittent bolus versus continuous infusion intravenous famotidine on gastric pH in critically ill trauma patients. DESIGN: Twenty patients were randomized to receive famotidine by intermittent bolus or continuous infusion for 24 hours. Patients fasted during the study period. Hourly gastric pH measurements were made using an indwelling sensor/sump tube. SETTING: The study was conducted in a university teaching hospital. PARTICIPANTS: Adult patients admitted to the neurosurgical or surgical/trauma intensive care unit within 72 hours of traumatic injury were enrolled in the study if they had two consecutive hourly gastric pH readings of < 4 without receiving antacids, sucralfate, or histamine2-antagonists. MAIN OUTCOME MEASURES: Groups were compared with regard to (1) total dose of famotidine received/24 hours, and (2) number of dosage changes required to maintain a gastric pH value of > or = 4. RESULTS: The median dose of famotidine required to maintain a gastric pH > or = 4 was 50 mg/24 h (25th-75th percentiles = 40-55 mg) in the intermittent bolus group compared with 42 mg/24 h (25th-75th percentiles = 42-52 mg) in the continuous infusion group (p = 0.9577). A dosage increase was required by 5 of 8 patients (62 percent) receiving intermittent bolus therapy, whereas only 2 of 8 patients (25 percent) in the continuous infusion group required a dosage adjustment (p = 0.315, power = 0.318). CONCLUSIONS: Intravenous famotidine (40-50 mg/d) effectively controlled gastric pH in critically ill trauma patients. Patients treated with intermittent bolus therapy required slightly more drug and more frequent dosage adjustments to achieve a gastric pH > or = 4. These differences did not reach statistical significance.

Adult↗
PubMedDate not supplied

Disease-based assessment of peripheral vascular disease in nursing facility patients.

OBJECTIVE: To determine the frequency of diagnosis of peripheral vascular disease (PVD) and selected related conditions in patients in a nursing facility, to determine the frequency of patients with risk factor(s) for or clinical evidence of PVD but without a diagnosis of PVD or a related condition, and to determine the frequency with which patients with and without a diagnosis of PVD or a related condition were treated with drug and nondrug therapies. DESIGN: A multicenter, disease-based, retrospective evaluation. SETTING: 41 nursing facilities in 6 regions of the US. PATIENTS: 4038 patients in a nursing facility: 827 patients with a PVD or related diagnosis; 2719 patients without a PVD or related diagnosis but with risk factor(s) for or clinical evidence of PVD; and 492 patients without a PVD or related diagnosis, risk factor(s), and clinical evidence. MAIN OUTCOME MEASURES: Evidence of disease and drug therapy for PVD. RESULTS: PVD was documented in 21% of patients; another 67% had risk factor(s) for or clinical evidence of PVD but no diagnosis of PVD or a related condition. Pentoxifylline was prescribed for 3% of the total sample and 12% of patients with PVD or a related condition. CONCLUSIONS: PVD appears to be inadequately evaluated in patients in a nursing facility. Disease treatment strategies should be developed and implemented to educate healthcare professionals and the general public about the need to acknowledge, assess, and treat PVD and related conditions.

Adult↗
PubMedDate not supplied

End-tidal carbon dioxide monitoring during cardiopulmonary resuscitation.

The end-tidal carbon dioxide (CO2) concentration has been found to correlate with cardiac output during and after cardiopulmonary resuscitation (CPR) in animal models. We monitored end-tidal CO2 values continuously during cardiac resuscitation in 23 humans while ventilation was held constant with a computer-controlled CPR Thumper. This report focuses on ten of the 23 patients who experienced return of spontaneous circulation (ROSC) during monitoring. There was no significant difference in the end-tidal CO2 value of patients without ROSC (1.8% +/- 0.9%) and the end-tidal CO2 value of patients before ROSC in patients who had ROSC (1.7% +/- 0.6%). The end-tidal CO2 concentration increased immediately in all patients who had ROSC, from 1.7% +/- 0.6% to 4.6% +/- 1.4%, then gradually returned to a new baseline (3.1% +/- 0.9%). Change in the end-tidal CO2 value was often the first clinical indicator that ROSC had occurred. Our findings suggest that end-tidal CO2 monitoring may provide clinically useful information that can be used to guide therapy during CPR.

Adult↗