Biomedical subjects

N E Robinson

Publications and source records attributed to N E Robinson.

At least 91 records · Page 5Linked to original sources

PubMed1994

Need for advanced cardiac life-support training in rural, community hospitals.

OBJECTIVE: To define the relative needs of the staffs of rural, community hospitals for training in advanced cardiac life support (ACLS), identify weaknesses, and modify a standard ACLS course to meet these needs. DESIGN: Prospective assessment of knowledge and skills relating to the practice of ACLS. SETTING: Rural, community hospitals in southern Wisconsin. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A well-validated, multiple-option, precourse test for life-support knowledge and clinical judgment was administered to the staff nurses, respiratory therapists, and practicing physicians of 12 rural, community hospitals in southern Wisconsin before their participation in a modified, extended, ACLS course, using the pre-1992 American Heart Association standards and guidelines. Testing was accomplished over 4 yrs. Detailed item analysis of the test was performed. A total of 461 persons participated. Overall, physicians performed better (p < .001) than did the nurses. Precourse difficulties included electrocardiographic rhythm strip interpretation, particularly with identification of the atrioventricular (A-V) blocks. Only 39.6% of the nurses and 64.1% of the physicians correctly identified third-degree A-V block. One third of the nurses and 22% of the physicians did not correctly identify coarse ventricular fibrillation. The pharmacologic properties and utility of atropine and epinephrine were not understood. Propranolol was selected for treatment of third-degree A-V block by 31.6% and 22.8% of the nurses and the physicians, respectively. Neither group was able to accurately distinguish between the components of disturbances in acid-base balance. The esophageal obturator airway tube was not a familiar tool to any of the groups. No improvement in overall performance on pretests occurred across the calendar years of the study. CONCLUSIONS: There is a need for ACLS training in community hospitals. Educational programs for physicians and staffs should be designed to meet that need.

Clinical Competence↗

PubMed1994

Effect of advanced cardiac life-support training in rural, community hospitals.

OBJECTIVES: To define the effectiveness of training personnel in rural, community hospitals in advanced cardiac life support (ACLS) and the changes that result in the process and quality of care to patients with ischemic heart disease that can be attributed to participation by team members in an ACLS course. DESIGN: Case-controlled, retrospective abstraction of hospital records of 869 consecutive patients with ischemic heart disease, who were admitted during the year preceding and the year following the ACLS course. SETTING: Seven rural, community hospitals in Wisconsin. SUBJECTS: Physicians, nurses, and other critical care staff (others). INTERVENTIONS: Training in ACLS using 12 3-hr sessions in an interdisciplinary format by a multidisciplinary faculty. MEASUREMENTS AND MAIN RESULTS: Rates of successful attainment of the terminal behavior objectives by physicians and nurses were 84.0% and 78.8%, respectively. Less than 50% of others achieved a satisfactory level of competence. Performance on an examination of cognitive ability improved significantly for all groups (p < .005 for nurses; p < .05 for physicians). Enhancement of knowledge base and integrative skills occurred in all areas of designated ACLS content. Difficulty remained apparent relative to the pharmacologic effects of epinephrine and atropine. No statistically significant deterioration in didactic knowledge base could be detected 1 to 2 yrs after completion of the ACLS course. Slight deterioration in intubation and defibrillation skills occurred in < 3 months after completion of the course. Substantial costs were encumbered by the hospitals, despite the free training provided to the institutions. After ACLS training had been given, overall mortality rates decreased from 17.4% to 13.4% (p < .05). A pooled estimate of the decrease in the mortality rate was 1.4 +/- 3.8%/quarter. Across the entire spectrum of severity of illness, the probabilities for survival increased at a given severity of illness following completion of the course (p = .06). When extremes of severity of illness were excluded from the analysis, the differences in probability for survival over the midrange of severity were statistically significant (p < .05). CONCLUSIONS: Training directed to the entire team likely to participate in the provision of ACLS in the community hospital favorably affects the overall practice of ACLS and the survival rate of patients with ischemic heart disease.

Aged↗

PubMed1994

Evaluation of partial arytenoidectomy as a treatment for equine laryngeal hemiplegia.

The efficacy of partial arytenoidectomy was assessed in 6 Standardbred horses, with surgically induced laryngeal hemiplegia, at rest (Period A) and during exercise at speeds corresponding to maximum heart rate (Period C) and 75% of maximum heart rate (Period B). Peak expiratory and inspiratory airflow rate (PEF and PIF), and expiratory and inspiratory transupper airway pressure (PUE and PUI) were measured and expiratory and inspiratory impedance (ZE and ZI) were calculated. Simultaneously, tidal breathing flow-volume loops (TBFVL) were acquired using a respiratory function computer. Indices derived from TBFVL included airflow rates at 50 and 25% of tidal volume (EF50, IF50, EF25, and IF25) and the ratios of expiratory to inspiratory flows. Measurements were made before left recurrent laryngeal neurectomy (baseline), 2 weeks after left recurrent laryngeal neurectomy (LRLN) and 16 weeks after left partial arytenoidectomy coupled with bilateral ventriculectomy (ARYT). After LRLN, during exercise Periods B and C, Z1 and the ratio of EF50/IF50 significantly increased and PIF, IF50 and IF25 significantly decreased from baseline values. At 16 weeks after ARYT, Z1 returned to baseline values during Periods B and C. Although PIF, IF50, IF25, PEF/PIF, and EF50/IF50 returned to baseline values during Period B, these indices remained significantly different from baseline measurements during Period C. After ARYT, TBFVL shapes from horses during Period C approached that seen at the baseline evaluation. Partial arytenoidectomy improved upper airway function in exercising horses with surgically induced left laryngeal hemiplegia, although qualitative and quantitative evaluation of TBFVLs suggested that some flow limitation remains at near maximal airflow rates. These results indicate that, although the procedure does not completely restore the upper airway to normal, partial arytenoidectomy is a viable treatment option for failed laryngoplasty and arytenoid chondropathy in the horse.

Animals↗

PubMed1994

Inhibitory nerve distribution and mediation of NANC relaxation by nitric oxide in horse airways.

The distribution of inhibitory nerves and the mediator of the inhibitory nonadrenergic noncholinergic (iN-ANC) nervous system were investigated in smooth muscle preparations from seven regions of equine airways. In tissues incubated with atropine and precontracted with histamine, electrical field stimulation produced frequency-dependent relaxation, and the magnitude of the relaxation decreased from trachea to central bronchi and was absent in peripheral airways. The degree of relaxation in bronchi was not simply a function of bronchial size or generation. Propranolol inhibited part of the relaxation only in the cranial trachealis. After propranolol, NG-nitro-L-arginine, a nitric oxide (NO) synthase inhibitor, eliminated the remaining relaxation in all preparations. This effect was reversed by L-arginine, the NO precursor, but not by D-arginine. Exogenous NO concentration dependently relaxed trachealis. These results indicate that: 1) adrenergic innervation is limited to cranial trachealis, 2) iNANC nerves supply the trachea and central bronchi, and 3) NO mediates iNANC function.

Animals↗

PubMed1994

Modulation of bronchial smooth muscle function in horses with heaves.

Four mechanisms that modulate airway smooth muscle function in normal horses were studied in the bronchi of horses affected by the airway obstructive disease heaves. Results were compared with data from historical controls studied by the same personnel in the same laboratory. Rings from the left cranial lobar bronchus (LB1) and small bronchi (5 mm OD) were suspended in muscle baths, and the isometric tension were measured. The inhibitory nonadrenergic noncholinergic (iNANC) function was studied in LB1. After the LB1 segments were pretreated with atropine and contracted with histamine, electrical field stimulation (EFS) induced little or no relaxation, indicating iNANC dysfunction in horses with heaves. Bronchi from animals with heaves were hyporesponsive to EFS and acetylcholine. Epithelial removal augmented the contractile response of small bronchi to acetylcholine more in animals with heaves than in control animals, indicating an enhanced function of epithelial-derived relaxing factor. In contrast, cyclooxygenase inhibition with meclofenamate (10(-6) M) increased the EFS-induced contraction of small bronchi less in affected horses than in control horses, suggesting a change in prostaglandin production in favor of excitatory prostanoids. We conclude that in the bronchi of horses with heaves; the iNANC function is defective, the response of smooth muscle to cholinergic activation is diminished, the production of epithelial-derived relaxing factor is enhanced, and the inhibitory function of prostanoids is reduced.

Acetylcholine↗

PubMed1994

Substance P and calcitonin gene-related peptide-like immunoreactive nerve fibers in lungs from adult equids.

Distribution of pulmonary nerves immunoreactive for either substance P or calcitonin gene-related peptide was determined, using immunohistochemical methods on healthy lungs from adult equids. The overall patterns of distribution of substance P and calcitonin gene-related peptide-like immunoreactivity were similar. Distribution of immunoreactive nerves was not uniform throughout the lungs; nerve fibers immunoreactive for these peptides were more frequently observed near the hilus of the lung than in the caudal lobes or in the periphery of the lung. Nerve fibers immunoreactive for substance P or calcitonin gene-related peptide were most abundant in the lamina propria of the trachea and larger airways, particularly within and directly below the airway epithelium; they were also frequently associated with bronchial and pulmonary vessels. Presence of nerve fibers immunoreactive for substance P and calcitonin gene-related peptide in peribronchial neural ganglia indicated that these sensory nerves may modulate parasympathetic regulation of pulmonary function. Nerve fibers immunoreactive for substance P and calcitonin gene-related peptide were, therefore, well placed to detect inhaled agents and to contribute to the pulmonary response to irritants and pathogens.

Afferent Pathways↗

PubMed1994

Tidal breathing flow-volume loops in horses with recurrent airway obstruction (heaves).

Tidal breathing flow-volume (TBFV) loops were determined in a group of control horses and in horses affected with recurrent airway obstruction (heaves). The latter group was studied when the condition was in remission and under increasing amounts of airway obstruction as reflected by measurements of change in pleural pressure, pulmonary resistance, and dynamic compliance. The TBFV loops of control horses had biphasic inspiratory and expiratory patterns; peak inspiratory and peak expiratory flows were detected early in inspiration and expiration, respectively. Tidal volume was unaffected by heaves, but at all stages of heaves, respiratory frequency was increased principally because of shorter inspiratory time, and therefore, inspiratory flow rate was increased. In horses with heaves, TBFV loops did not have a biphasic pattern; peak inspiratory flow was observed late in inspiration, and peak expiratory flow was observed early in expiration. As airway obstruction became more severe, peak expiratory flow increased as pulmonary resistance increased so that, during severe airway obstruction, TBFV loops had a characteristic appearance with high peak expiratory flow early in expiration followed by low flow rate.

Airway Obstruction↗

PubMed1993

Adrenergic and peptidergic innervation of the trachealis muscle in the normal horse: a preliminary report.

The tone of respiratory smooth muscle is largely determined by the input from autonomic nerves. The distribution of adrenergic and selected nonadrenergic, non-cholinergic (NANC) nerves in the normal equine trachealis muscle was investigated using immunohistochemistry. The smooth muscle of the trachealis was found to contain numerous nerves immunoreactive for an enzymatic marker of adrenergic nerves, as well as many nerves immunoreactive for a putative NANC neurotransmitter, peptide histidine isoleucine, a potent bronchodilator. The tissue surrounding the respiratory smooth muscle contained numerous nerves immunoreactive for the neuropeptides substance P and calcitonin gene-related peptide, which can cause marked vasodilation and bronchoconstriction. The complex innervation of the equine trachea should be kept in mind when interpreting the results of physiological experiments.

Animals↗

PubMed1993

Independent modulation of horse airway smooth muscle by epithelium and prostanoids.

The effects of epithelial removal and cyclooxygenase inhibition on contractions induced by exogenous acetylcholine (ACh) and electrical field stimulation (EFS) were evaluated in horse tracheal strips and bronchial rings. Epithelial removal potentiated the response to ACh but had no influence on the response to EFS. The effect of epithelial removal was not altered by pretreating the tissues with meclofenamate, a cyclooxygenase inhibitor. In trachealis strips, meclofenamate augmented contractions induced by EFS but not by ACh. In bronchial rings, meclofenamate augmented EFS-induced contraction to a greater extent than ACh-induced contraction. These effects of meclofenamate were epithelium-independent. We conclude that horse airway epithelium produces a relaxant factor that is not a prostanoid. Endogenous prostanoids originating from non-epithelial sites inhibit only cholinergic nerves in the trachea but both parasympathetic nerves and smooth muscle in the bronchi.

Acetylcholine↗

PubMed1993

Flunixin meglumine blocks frusemide-induced bronchodilation in horses with chronic obstructive pulmonary disease.

Six horses that developed acute airway obstruction (heaves) when housed in a barn and fed poor-quality hay were studied. Airway obstruction was verified by a maximal change in pleural pressure during tidal breathing (delta Pplmax) of at least 15 cmH2O. Frusemide (1.0 mg/kg bwt) or an equivalent volume of vehicle was then administered intravenously (iv) and lung function was measured 15, 30, 60, 120, 180, 240 and 300 mins after drug administration. The effect of frusemide on lung function was also studied after treatment of horses with the cyclooxygenase inhibitor flunixin meglumine (1.1 mg/kg every 8 h for 2 days before the experiment). Frusemide significantly reduced the delta Pplmax beginning 15 mins after drug administration. This effect persisted for 5 h. The reduction in delta Pplmax was due partly to an increase in dynamic compliance and partly to a decrease in pulmonary resistance. Tidal volume and respiratory frequency were unaffected by frusemide. Vehicle had no effect on lung function. Flunixin meglumine abolished the effect of frusemide on airway calibre but did not prevent diuresis. These results indicate that the effect of frusemide on airways of horses with heaves persists for at least 5 h, is mediated through prostanoids, and is not a result of diuresis.

Analysis of Variance↗

PubMed1993

Airborne dust and aeroallergen concentration in a horse stable under two different management systems.

Airborne dust concentration (ADC) was measured in 2 different horse management systems using an Andersen cascade impactor in the box-stall, and a personal Marple cascade impactor attached to the halter to measure ADC in the breathing zone. The levels of aeroallergens implicated in chronic obstructive pulmonary disease were measured by radioallergosorbent-inhibition immunoassay. A conventional management system (System C) utilising hay feed and straw bedding, and a recommended environment (System R) utilising wood shaving bedding and a complete pelleted diet were studied. In the stall, total and respirable ADC (geometric mean) were significantly higher in System C (2.55 mg/m3; 0.44 mg/m3, respectively) than in System R (0.70 mg/m3; 0.20 mg/m3, respectively). In System C, the total and respirable ADC in the breathing zone (17.51 mg/m3; 9.28 mg/m3) were much higher than in the stall, but values in both regions were similar in System R (0.52 mg/m3; 0.30 mg/m3). Major aeroallergens were significantly higher in System C than in System R: Micropolyspora faeni (1423 ng/m3 and 705 ng/m3), Aspergillus fumigatus (1823 ng/m3 and 748 ng/m3), and mite allergens (1420 ng/m3 and 761 ng/m3). Measurement of ADC with personal samplers indicates that the very high inhalation challenge in the breathing zone is not reflected in measurements of stall air quality. When compared with System C, System R produced only 3% of the respirable dust burden in the breathing zone and a decreased aeroallergen challenge.

Air Microbiology↗

PubMed1993

The airway response of horses with recurrent airway obstruction (heaves) to aerosol administration of ipratropium bromide.

The airway response to aerosol administration of the anticholinergic agent ipratropium bromide was determined in 8 horses with recurrent airway obstruction (heaves). The reversibility of airway obstruction was confirmed by measuring lung function before and during stabling; and by determining the response to atropine administration (0.02 mg/kg bwt intravenously). The dose-response to ipratropium bromide was determined using a Williams square design experiment in which 25, 50 or 75 micrograms ipratropium bromide/ml (4 ml/100 kg bwt) or the same volume of vehicle was administered to each horse by nebulisation. Lung function was measured before and 1 and 4 h after nebulisation. Vehicle had no effect on lung function. Ipratropium decreased the maximal change in pleural pressure during tidal breathing (delta Pplmax) and pulmonary resistance (RL) and increased dynamic compliance (Cdyn). At the 1 h measurement period, the effect on RL and Cdyn was dose-dependent. A separate experiment demonstrated that the duration of action of ipratropium was between 4 and 6 h.

Administration, Inhalation↗

PubMed1993

ACh release from horse airway cholinergic nerves: effects of stimulation intensity and muscle preload.

This study was conducted to determine the effects of stimulation parameters and muscle preload on acetylcholine (ACh) release induced by electrical field stimulation (EFS) of horse airway cholinergic nerves. Trachealis strip bundles were prepared and suspended in 2-ml tissue baths. The tissues were stimulated three to five times for 30 min each. Increasing frequency (0.5-16 Hz) and voltage (5-20 V) increased ACh release; increasing pulse duration (0.5-3 ms) had only a minor effect. Alterations in muscle preload (2-20 g) had no effect on ACh release. ACh release was fairly constant for up to five repeated stimulation periods with the same EFS parameters. Stimulation of the tissues for 15 min released the same amount of ACh as 30 min if the amount was expressed as picomoles per gram per minute, suggesting that ACh release rate was constant during the 30-min period of stimulation. Atropine (10(-6) M) potentiated the release of ACh four- to fivefold, presumably by removing the autoinhibitory effect of ACh on the cholinergic nerves. Tetrodotoxin (10(-6) M) abolished the EFS-induced ACh release.

Acetylcholine↗

PubMed1993

Prejunctional alpha 2-adrenoceptors inhibit acetylcholine release from cholinergic nerves in equine airways.

To determine the presence and function of alpha 2-adrenoceptors on cholinergic nerves innervating horse airway smooth muscle, the effects of some alpha 2-adrenoceptor agents on contractions of and acetylcholine (ACh) release from equine airway smooth muscle preparations were studied. Muscle contractions were elicited by either electrical field stimulation (EFS) or exogenous ACh. ACh release was induced by EFS and measured by high-pressure liquid chromatography and electrochemical detection. The alpha 2-adrenoceptor agonists clonidine (10(-7) to 10(-5) M) and UK-14,304 (10(-8) to 10(-6) M) concentration dependently inhibited ACh release and the contractile response to EFS but not the response to exogenous ACh. This inhibition was attenuated by the alpha 2-adrenoceptor antagonists yohimbine and idazoxan but not by the alpha 1-adrenoceptor antagonist prazosin. These results indicate that alpha 2-adrenoceptors exist on cholinergic nerves innervating equine airway smooth muscle, and activation of these receptors inhibits cholinergic neurotransmission. The observation that yohimbine alone had little effect on the contractile response to EFS suggests that, under these experimental conditions, endogenous norepinephrine had no influence on tracheal cholinergic neurotransmission via prejunctional alpha 2-adrenoceptors.

Acetylcholine↗

PubMed1993

Use of flow-volume loops to evaluate upper airway obstruction in exercising standardbreds.

Flow-volume loops generated from 6 Standardbreds at rest and during treadmill exercise were evaluated for their use in detecting upper airway obstruction. Tidal breathing flow-volume loops (TBFVL) were obtained from horses at rest and exercising at speeds corresponding to 75% of maximal heart rate and at maximal heart rate. The TBFVL were evaluated, using a pulmonary function computer; calculated indices describing airflow rate and expiratory-to-inspiratory airflow ratio for individual loops were determined. In addition to TBFVL indices, standard variables of upper airway function also were measured: peak airflow, peak pressure, and calculated inspiratory and expiratory impedances. Measurements were recorded before left recurrent laryngeal neurectomy (LRLN; baseline) and 14 days after surgically induced left laryngeal hemiplegia. When horses were at rest, TBFVL shape and indices describing the loop were highly variable. In contrast, in exercising horses, TBFVL shape was consistent and coefficients of variation of loop indices were less during exercise than at rest. After LRLN, TBFVL from exercising horses indicated marked inspiratory airflow limitation, while the expiratory airflow curve was preserved. Peak inspiratory flow rate and inspiratory flow at 50 and 25% of tidal volume decreased, and the ratio of peak expiratory to inspiratory airflow and that of midtidal volume expiratory and inspiratory airflow rates increased significantly (P < 0.05). Inspiratory impedance also increased after LRLN. Although in resting horses TBFVL were not a useful indicator of upper airway obstruction, examination of TBFVL from exercising horses allowed objective, specific, and repeatable detection of upper airway obstruction. The technique was noninvasive, rapid, and well tolerated by horses; thus, it is a potentially valuable clinical diagnostic test.

Airway Obstruction↗

PubMed1993

In vitro effects of alpha 2-adrenergic receptor stimulation on cholinergic contractions of equine distal airways.

In horses with noninduced, reversible airway obstruction (heaves), pulmonary function is improved after sedation with the alpha 2-adrenergic agonist xylazine. The mechanism of this effect is undetermined. Because the predominant excitatory innervation of equine airways is cholinergic, the influence of alpha 2-adrenergic receptor stimulation on the response of isolated distal airways to cholinergic stimulation was determined. Distal bronchial segments from 22 healthy horses were suspended in isolated organ baths where their mechanical responses to various stimuli could be studied. Each tissue was incubated with one of several concentrations of clonidine, clonidine vehicle, or clonidine plus tolazoline. Then, the contractile response of the tissues to either cumulative acetylcholine (ACh) addition or cumulative electrical field stimulation (EFS) was recorded. All contractile responses evoked by EFS were mediated through stimulation of cholinergic airway nerves. Clonidine had no effect on the contractile response of distal airway segments to exogenous ACh. However, clonidine (at concentrations > 10(-5) M) significantly (P < 0.05) diminished the contractile response of the distal airway segments to EFS. This inhibitory effect of clonidine was not observed in the presence of tolazoline. Similar results were observed when the less-selective alpha 2-adrenergic agonist xylazine was exposed to the isolated segments instead of clonidine. Because EFS-but not exogenous ACh-induced contractions were inhibited, alpha 2-adrenergic receptor stimulation apparently causes presynaptic inhibition of the cholinergic nerves innervating distal portions of the bronchi of horses.

Acetylcholine↗

PubMed1993

Cardiovascular responses to exogenous platelet-activating factor (PAF) in anesthetized ponies, and the effects of a PAF antagonist, WEB 2086.

The effects of exogenous platelet-activating factor (PAF) were determined in anesthetized ponies. Administration of PAF induced a decrease in cardiac index that resulted in systemic hypotension. This was followed by tachycardia, hypertension, and a return of cardiac index to baseline. Pulmonary arterial pressure increased markedly because of pulmonary vasoconstriction. Exogenous PAF also caused leukopenia and thrombocytopenia. The specific PAF receptor antagonist (WEB 2086) blocked all PAF-induced changes. Flunixin meglumine, a cyclooxygenase inhibitor, abolished the pulmonary hypertension and tachycardia, and attenuated the systemic hypotension but did not change the PAF-induced peripheral cellular changes. The PAF antagonist also inhibited platelet aggregation induced by PAF in vitro. The PAF-induced changes are similar to those reported after endotoxin exposure in horses.

Anesthesia, Intravenous↗

PubMed1993

Distribution of dopamine beta-hydroxylase and neuropeptide Y-immunoreactive nerves in healthy equine lungs.

Immunohistochemical methods were used to determine the distribution of pulmonary nerves containing either an enzymatic marker of adrenergic nerves, dopamine beta hydroxylase, or the putative neurotransmitter neuropeptide Y in 7 equids with healthy lungs. Nerves immunoreactive for these substances were found on airway smooth muscle in nearly all the samples of healthy equine lung examined. These nerves were generally more numerous in the larger airways but could be detected even in noncartilaginous bronchioles. Pulmonary and bronchial vessels also contained numerous immunoreactive nerves. On the basis of these findings, we suggest that dopamine beta-hydroxylase- and neuropeptide Y-immunoreactive nerves may be involved in the regulation of airway and vascular diameter in equids.

Animals↗