Degree Of Hyperreactivity Research Articles

Comparison of subcutaneous sedation with alfaxalone or alfaxalone-midazolam in pet guinea pigs (Cavia porcellus) of three different age groups

To compare the cardiorespiratory effects, quality and duration of sedation of 2 subcutaneous sedation protocols for noninvasive procedures in guinea pigs (GPs). 24 pet GPs (15 females, 9 males) of 3 different age groups: infant (n = 8), juvenile (8), and adult (8). The study design was a randomized, crossover, blinded, clinical trial with a washout period of at least 7 days between protocols. Guinea pigs were sedated SC with alfaxalone (5 mg/kg; group A) or alfaxalone (5 mg/kg) and midazolam (0.5 mg/kg; group A + M) to facilitate blood sampling, radiography, or abdominal ultrasonography. Vital parameters, hemoglobin saturation (SpO2), and sedation scores were recorded every 5 minutes. Mean heart rate was lower in group A than group A + M (P = 0.001), and respiratory rate was significantly (P = 0.001) decreased relative to baseline during sedation in both groups. The SpO2 remained above 95% in both sedation groups. Rectal temperature was significantly (P = 0.001) lower during recovery versus baseline. Onset of sedation was shorter and the duration longer in group A + M than in group A. The duration and depth of the sedation was different between age groups (P = 0.001), being longer and deeper in adults. Bruxism, hectic movements, twitching, and some degree of hyperreactivity were observed during 41 of the 48 sedations. Subcutaneous administration of alfaxalone provided reliable sedation for nonpainful procedures in GPs. When combined with midazolam, alfaxalone provided longer and deeper sedation that was more significant in adults than in younger patients.

Airway hyperreactivity and peripheral airway dysfunction in influenza A infection.

We studied 39 consecutive college students with documented nonpneumonitic influenza A/Victoria/3/75/H3N2 infection to examine alterations in pulmonary mechanics and airway reactivity to cholinergic challenge, and to assess the effect of the antiviral agent amantadine on these changes. Thirty-six of the 39 subjects (92 per cent) demonstrated diminished forced flow rates and decreased density-dependent forced flow rates while breathing a helium-O2 mixture as compared to an air mixture. On initial evaluation, there was no significant difference in forced flow rates or density dependence between a group of 18 subjects treated with amantadine and 21 subjects given a placebo. However, the placebo group demonstrated further decreases in density dependence 7 days after initial presentation, whereas the amantadine group demonstrated a significant increase in density dependence (P less than 0.05), which suggested an accelerated improvement in peripheral airway dysfunction in the treated group. After inhalation of carbachol aerosol, 25 subjects showed a significant (P less than 0.05) increase in total respiratory resistance that was prolonged and independent of hay fever history. Airway hyperreactivity gradually diminished during a 7-week period in both groups. There was no significant difference in the initial degree of hyperreactivity or in the rate of improvement between groups. These data suggest that nonpneumonitic influenza infection may be associated with both an inflammatory response predominantly in the peripheral airways and transient bronchial hyperreactivity. By means of its antiviral effect, amantadine may arrest the proliferation of virus and associated inflammatory response in peripheral airways, but airway hyperreactivity presumably related to initially damaged airway depithelium is not attenuated by inhibition of viral replication after infection has been established.

Influence of spasmogen inhalation by guinea pigs upon subsequent demonstration of ovalbumin-induced hyperreactivity in isolated airways tissues

Guinca pigs were sensitized with ovalbumin (i.p.) 14 days before use. In vivo airway hyperreactivity induced by ovalbumin inhalation was determined by challenging with aerosolized spasmogen (5-hydroxytryptamine [5-HT] methacholine, the thromboxane-mimetic, U-46619, or adenosine) 24 hr before (7 days with adenosine) and again 18–24 hr after the ovalbumin inhalation. One hour later they were killed and isolated airways perfused lung halves and tracheal spirals were set up for determination of tissue sensitivity to carbachol, histamine, and adenosine. This study examines whether the spasmogen interferes with the ovalbumin-induced in vitro hyperreactivity and the combined effects of ovalbumin followed by spasmogen challenge upon tissue sensitivity. The influence of the spasmogen upon the in vitro measurement of ovalbumin-induced hyperreactivity was variable, depending upon which spasmogen was used and whether the lung or traches was examined. The inhalation of the spasmogen in ovalbumin-challenged guinea pigs had clear effects upon the subsequent measurement of tissue sensitivity. This depended upon the spasmogen used, but 5-HT, methacholine, and U-46619 usually depressed responsiveness, while adenosine was without significant effect. As a consequence, the appearances of in vitro hyperreactivity due to the ovalbumin challenge could be masked (e.g., bolus doses of agonist in the trachea when 5-HT was the spasmogen) or the degree of hyperreactivity could be enhanced (e.g., in the perfused lung when adenosine was the spasmogen). Thus, isolated airways tissues should not be used for evaluating tissue sensitivity when the animals have been previously exposed to inhalations of spasmogens.

An objective method to record changes in nasal reactivity during treatment of non-allergic nasal hyperreactivity.

Non-allergic nasal hyperreactivity is a common problem and many patients suffer from daily symptoms demanding medication. Hitherto there exists no objective method to study congestional changes in clinical practice, to evaluate the efficacy of different therapies. This study is an attempt to develop a method for this purpose. Eleven patients with non-allergic nasal hyperreactivity entered the trial. A histamine challenge model with three different histamine concentrations was used. Recordings of the reactivity of the nasal mucosa were made with rhinostereometry before and after 14 days of topical treatment with budesonide 200 micrograms/day. The results were compared to symptom scores before and after treatment. It was found that there was a significant improvement after treatment both with regard to symptom score and to the recorded reactivity of the nasal mucosa. There was a correlation between symptom score and recorded reactivity before treatment, but not after treatment. The results indicate that the symptom score technique is sufficient in situations where only a semiquantitative method is required. However, when studying changes in the degree of hyperreactivity, the demands for an objective measuring method is greater. The study indicates that the presented method may be adapted for this purpose.

Long term effects of artificial ventilation in neonates.

In order to evaluate long term effects of artificial ventilation, 27 children, who had been ventilated for more than five days in their neonatal period, were reinvestigated at school age. In 5 of them bronchopulmonary dysplasia had been diagnosed. Seven had more than 10 upper respiratory tract infections per year and 9 had recurrent obstructive airway disease. On pulmonary function testing (n = 23) 19% showed some airway obstruction, and in 43% bronchial hyperreactivity was found by bronchial provocation with histamine. There was a significant correlation (p less than 0.05) between bronchial hyperreactivity and the duration of neonatal ventilation. The degree of hyperreactivity (PC20, FEV1) also correlated with birth weight (p less than 0.005) and gestational age (p less than 0.02). It is concluded that prolonged neonatal ventilation might be followed by bronchial hyperreactivity, especially in the small and premature newborn.