Effects of magnesium sulfate infusion on clinical signs and lung function of horses with severe asthma

The Association Between Dietary Magnesium Intake and Pulmonary Function: Recent Fndings from NHANES 2007-2012

This article aims to study the correlation between dietary magnesium intake and pulmonary function, utilizing data from the National Health and Nutrition Examination Survey (NHANES) database. This cross-sectional study examined representative samples of adults from the USA (n = 818; NHANES 2007-2012) to explore the correlation between magnesium intake and pulmonary function. We obtained the average magnesium intake over 2 days, as well as measured pulmonary function parameters, including forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV1/FVC, peak expiratory flow rate (PEF), and forced expiratory flow between 25 and 75% of FVC (FEF25-75%). Weighted multivariable linear regression was used to investigate the relationship between magnesium intake and pulmonary function. Additionally, subgroup analyses, interaction tests, and sensitivity analyses were conducted. Weighted multiple linear regression models revealed a significant positive correlation between magnesium and pulmonary function, even after adjusting for all included confounding variables. When we categorized magnesium intake into tertiles, we found that participants in the highest tertile of magnesium intake had significantly higher values for FVC (β: 898.54, 95%CI: 211.82-1585.25), FEV1 (β: 858.16, 95%CI: 212.41-1503.91), FEV1/FVC (β: 0.024, 95%CI: 0.004-0.044), PEF (β: 1324.52, 95%CI: 481.71-2167.33), and FEF25-75% (β: 831.39, 95%CI: 84.93-1577.84). Upon stratifying the data by age and sex, it was observed that this positive correlation was particularly pronounced among men aged 40-79. At the same time, the stability of the results was further confirmed by sensitivity analyses. This study suggested that dietary magnesium intake may improve pulmonary function.

Intravenous magnesium sulphate in standing horses: effects on physiological parameters, plasma concentration of magnesium and nociceptive threshold tests

A bolus of 50 mg kg ^-1 MgSO₄ (treatment Mg) or the same volume of saline (treatment S) was infused over 15 minutes in 5 adult healthy horses. T0 was the end of the infusion. Physiological parameters were recorded throughout the study period. Measurements of electrical, thermal and mechanical nociceptive thresholds were performed at the pelvic limbs at baseline (before T0), and at specific timepoints. Blood samples were taken at fixed timepoints before, during and until 12 hours after the infusion. For statistical analysis, the 95% confidence intervals (CI's) for the differences in nociceptive thresholds between treatments were calculated. Physiological parameters were compared using a linear mixed model (global α = 0.05, with Bonferroni correction α = 0.0125). The concentrations of ions were also compared with baseline values at specific timepoints, using a linear mixed model. The Pearson's correlation coefficient was derived between the ion concentrations. The 95% CI's of thermal, mechanical and electrical thresholds were [-1; +2]°C, [0; +3] N and [-1; +1] mA (positive differences indicate higher thresholds for treatment Mg), respectively. Heart rate was significantly higher (p < 0.0001) and non-invasive systolic arterial pressure (p < 0.0001) and respiratory rate (p = 0.0002) significantly lower after treatment Mg compared to treatment S. Additionally, non-invasive systolic arterial pressure was significantly different at T45 (p < 0.001). Although mild changes in cardiovascular parameters and plasma concentrations were seen with intravenous administration of MgSO₄, no changes in nociceptive thresholds were detected in standing non-sedated horses.

Can bronchoconstriction and bronchodilatation in horses be detected using electrical impedance tomography?

BACKGROUND

Electrical impedance tomography (EIT) generates images of the lungs based on impedance change and was able to detect changes in airflow after histamine challenge in horses.

OBJECTIVES

To confirm that EIT can detect histamine-provoked changes in airflow and subsequent drug-induced bronchodilatation. Novel EIT flow variables were developed and examined for changes in airflow.

METHODS

Bronchoconstriction was induced using stepwise histamine bronchoprovocation in 17 healthy sedated horses. The EIT variables were recorded at baseline, after saline nebulization (control), at the histamine concentration causing bronchoconstriction (Cmax ) and 2 and 10 minutes after albuterol (salbutamol) administration. Peak global inspiratory (PIFEIT ) and peak expiratory EIT (PEFEIT ) flow, slope of the global expiratory flow-volume curve (FVslope ), steepest FVslope over all pixels in the lung field, total impedance change (surrogate for tidal volume; VTEIT ) and intercept on the expiratory FV curve normalized to VTEIT (FVintercept /VTEIT ) were indexed to baseline and analyzed for a difference from the control, at Cmax , 2 and 10 minutes after albuterol. Multiple linear regression explored the explanation of the variance of Δflow, a validated variable to evaluate bronchoconstriction using all EIT variables.

RESULTS

At Cmax , PIFEIT , PEFEIT , and FVslope significantly increased whereas FVintercept /VT decreased. All variables returned to baseline 10 minutes after albuterol. The VTEIT did not change. Multivariable investigation suggested 51% of Δflow variance was explained by a combination of PIFEIT and PEFEIT .

CONCLUSIONS AND CLINICAL IMPORTANCE

Changes in airflow during histamine challenge and subsequent albuterol administration could be detected by various EIT flow volume variables.

Research on Effect of Exosome Excreted by RAW264.7 Cell on Damage of Mice Lung Function and Its Mechanism

The exosome excreted by RAW264.7 cell was found to participate in the damage of lung function. Our purpose was to assess the exact mechanism. The animal experiment was adopted in our study. It was provided reference for clinical experiment. 30 healthy male rats were selected and assigned into normal control group, normal exosome group and LPS with exosome group by random number table followed by analysis of the size and form of exosome under electron microscope, the lung structural change by hematoxylin and eosin staining, TNF-α and IL-1β secretion by immunohistochemistry, and the expression of tightly bound protein one (ZO-1), closed protein, β-chain protein and two groups of exosome-marked protein (CD9 and CD63) by western blot. In normal control group, the lung structure was very integral with clear alveolar space. The cell wall was smooth relatively without exudation substance in alveolar space and mesenchyme. Normal exosome group showed relatively integral lung structure and thicker cell wall. The inside of alveolar space was very clear without exudation substance in alveolar space and mesenchyme. LPS + exosome group presented abundant inflammatory cells in alveolar space and mesenchyme with obvious bleeding. Inflammatory factor secretion such as TNF-α (1.334 ± 0.205%) and IL-1β (0.803 ± 0.097%)was significantly higher and the content of closed protein (0.203 ±0.017%) was lower in LPS with exosome group than the other two groups (P < 0.05). The exosome secreted by RAW264.7 cell after stimulation by lipopolysaccharide could impair the lung function in rats and is related with the decline of closed protein.

Pharmacokinetics of magnesium and its effects on clinical variables following experimentally induced hypermagnesemia

The objectives of this study were to describe pharmacokinetic and pharmacodynamic changes as a result of a single intravenous administration of magnesium sulfate (MgSO₄ ) to healthy horses. MgSO₄ is a magnesium salt that has been used to calm horses in equestrian competition and is difficult to regulate because magnesium is an essential constituent of all mammals. Six healthy adult female horses were administered a single intravenous dose of MgSO₄ at 60 mg/kg of body weight over 5 min. Blood, urine, and cerebrospinal fluid (CSF) samples were collected, and cardiovascular parameters were monitored and echocardiograms performed at predetermined times. Noncompartmental pharmacokinetic analysis was applied to plasma concentrations of ionized magnesium (Mg²⁺ ). Objective data were analyzed using the Wilcoxon rank-sum test with p < .05 used as a determination for significance. Plasma concentrations of Mg²⁺ increased nearly fivefold, ionized calcium (Ca²⁺ ) decreased by nearly 10%, and the Ca²⁺ to Mg²⁺ ratio declined more than 3.5-fold and remained different than baseline until 24 hr (p < .05). Significant changes were seen with urinary fractional excretion of electrolytes, cardiovascular parameters, and echocardiographic measurements. No changes were detected in CSF electrolyte concentrations. The decrease in Ca²⁺ result of hypermagnesemia supports the interaction between these cations. Alterations detected in plasma electrolyte concentrations and urinary fractional excretion of electrolytes may serve as biomarkers for regulatory control for the nefarious administration of MgSO₄ .

Clinical efficacy of bronchodilators in equine asthma: Looking for minimal important difference

BACKGROUND

Airway obstruction is the main trait of severe equine asthma that affects respiratory function and elicits detrimental effects on clinical presentation. Only few and underpowered clinical studies have investigated the impact of improvement in lung function induced by bronchodilators on the clinical signs of asthma-affected horses.

OBJECTIVES

To identify the minimal important difference (MID) in lung function elicited by bronchodilator leading to a meaningful improvement in clinical signs.

STUDY DESIGN

Pairwise meta-analysis and meta-regression analysis.

METHODS

Literature searches were performed for studies that investigated the effect of bronchodilator therapy on lung function and clinical condition of asthmatic horses. The relationship between the change in lung function variables and clinical score was analysed via random-effect meta-regression. One-point change of the Improved clinically Detectable Equine Asthma Scoring System (IDEASS) score was used to identify the MID.

RESULTS

A significant (P<0.05) relationship was found between the changes in IDEASS score and maximum change in transpulmonary pressure (ΔPpl_max ) or pulmonary resistance (R_L ). Since only the model resulting for R_L passed through the origin (Y-intercept when X = 0: -0.31, 95% CI -0.75 to 0.14), this variable was used to identify the MID correlated with a meaningful improvement in clinical signs. The resulting MID value was a change in R_L of 0.63 cm H₂ O/L/s (95% CI 0.33-0.94), representing the slope of meta-regression model (high quality of evidence).

MAIN LIMITATIONS

No long-term studies investigated the effect of bronchodilator agents on both lung function and clinical signs in asthmatic horses.

CONCLUSIONS

In conclusion, bronchodilator pharmacotherapy in equine asthma elicits clinically meaningful effect when R_L increases ≥1 cm H₂ O/L/s, a value indicating the MID. Assessing the MID based on change in R_L may improve the quality of evidence and the scientific impact of future clinical trials as it extends beyond the simple, and limiting, evaluation of statistical significance.