Recovery from neuromuscular block in dogs: restoration of spontaneous ventilation does not exclude residual blockade

ObjectiveTo evaluate if return of spontaneous ventilation to pre-relaxation values indicates complete recovery from neuromuscular blockade.Study designProspective, with each individual acting as its own control.AnimalsTen healthy adult female Beagle dogs weighing 6.2–9.4 kg.MethodsDogs were anesthetized with propofol, dexemedetomidine and isoflurane. Spontaneous ventilation was assessed by measuring end-tidal CO₂, expired tidal volume, peak inspiratory flow, respiratory rate and minute ventilation. Vecuronium 25 μg kg^?1 IV was administered and neuromuscular block was evaluated by measuring the train-of-four (TOF) ratio with acceleromyography in the hind limb. During spontaneous recovery from neuromuscular block, the TOF ratio when each ventilatory variable returned to baseline was recorded.ResultsThis dose of vecuronium produced moderate neuromuscular block in all dogs, with TOF ratio values of 0–18% at maximal block. Expired tidal volume, peak inspiratory flow and minute ventilation returned to pre-relaxation values when the median TOF ratio was ≤ 20%. The median TOF ratio was 42% when the end-tidal CO₂ returned to pre-relaxation values.Conclusions and clinical relevanceSignificant residual neuromuscular block could be measured at the hind limb with acceleromyography when ventilation had spontaneously returned to pre-vecuronium values. Monitoring spontaneous ventilation, including end-tidal CO₂, expired tidal volume, peak inspiratory flow or minute ventilation cannot be used as a surrogate for objective neuromuscular monitoring, and this practice may increase the risk of postoperative residual paralysis.     

Effects of changes in plasma pH,CO2 and ammonia on ventilation in trout

We investigated ventillatory responses to a plasma alkaloids and hypocapnia,a nd the basis for the ventilatory response to sodium bicarbonate (NaHCO₃) infusion in rainbow trout. Plasma alkalosis and hypocapnia created by infusion of sodium hydroxide (NaOH) did not cause hypoventilation, whereas infusion of hydrochloric acid (HCl) caused vigorous hyperventilation, associated with an acidosis, a reduction in blood O₂ content (Ca_{O 2}) and a release of circulating catecholamines. Infusion of NaHCO₃ stimulated ventilation and caused an increase in plasma pH, total carbon dioxide content (Ca_{CO 2}) and catecholamine levels, and a reduction in oxygen tension (Pa_{O 2}). Infusion of ammonium bicarbonate (NH ₄HCO₃) caused hyperventilation and was associated with an increase in Ca_{CO 2} and plasma total ammonia (C_amm) and ammonia gas (NH₃) concentration. Infusion of sodium chloride (NaClI) and Cortland's saline had no effect on ventilation. The results indicate that trout do not exhibit the ventilatory sensitivity to pH seen in terrestrial vertebrates. Ventilatory responses to NaHCO₃ appear to have been a result of reductions in Pa_{O 2}, a release of catecholamines and an increase in Ca_{CO 2} whereas responses to NH₄HCO₃ appear to have been a result of increases in Ca_{CO 2} and C_amm.     

Effects of prolonged epinephrine infusion on blood respiratory and acid-base states in the rainbow trout: Alpha and beta effects

Rainbow trout were infused continuously for 12h with epinephrine in the presence or absence of alpha-and/or beta-adrenergic blockade to characterize the specific adrenergic mechanisms involved in the control of blood acid-base status and oxygen transport capacity. Infusion of epinephrine, alone, produced a transient respiratory acidosis, as indicated by an increase in carbon dioxide tension and a decrease in whole blood pH, yet arterial oxygen tension was elevated. Red blood cell pH increased by approximately 0.2 pH units during epinephrine infusion and this increase as well as the increase in oxygen tension were prevented by pretreatment with propranolol (a beta-adrenergic antagonist). Epinephrine infusion during alpha-adrenergic blockade caused a prolonged elevation of blood carbon dioxide tension and abolished the increases in hematocrit and hemoglobin concentrations observed during epinephrine infusion alone. Infusion of the alpha-adrenergic agonists phenylephrine (an alpha₁ agonist) or clonidine (an alpha₂ agonist) caused respiratory acidosis (decreased pH, increased CO₂ tension) and a reduction in oxygen tension. Infusion of isoprenaline (a non-specific beta agonist) caused delayed increases in carbon dioxide and oxygen tensions. We speculate that the increased carbon dioxide tension observed during epinephrine infusion is a result of beta-adrenoceptor mediated inhibition of red blood cell bicarbonate dehydration and not branchial convective or diffusive adjustments. The effects of epinephrine on blood O₂ tension, content and carrying capacity are discussed with reference to the participation of alpha- and beta-adrenergic mechanisms at the gill, spleen and red blood cell.     

矿井通风变频自动控制方法研究

现有矿井风机的工频供电控制方式已不能满足目前矿井现代化生产的需求。通过研究矿井风机传统控制方式,设计了矿井通风变频自动控制系统。该系统采用变频器对风机进行变频调速,以达到对风压和风量的自动控制;通过检测风机轴承和电动机温度,由中央控制单元自动切换备用风机,提高了矿井生产的安全性和可靠性。     

机械通风在西北冬寒终年气干区的综合运用

我库通过8年实践，总结出一整套机械通风综合应用技术，不仅降低了储粮费用，同时提高了储粮的品质。     

蛋鸡舍湿墙降温设施的应用效果分析

通过对某鸡场三种不同的纵向通风与蒸发降温设施在夏季的使用效果的观察，证明纵向通风加湿帘系统在降低鸡舍环境温度、缓解热应激、降低鸡群生产性能下降幅度等方面效果最好。纵向通风与湿墙降温系统也具有一定的效果，从性价比来讲也不失为一种好的环境控制措施。     

论大型地下商场空调通风及防排烟

本文通过工程实例说明如何将大型地下商场的空调、通风及防排烟系统三者结合在一起，用一套风系统来实现其各自作用的。     

变频调速器在机械通风与谷物冷却中的应用前景

为了降低综合成本，谋求经济效益最大化，在机械通风与谷物冷却中采用变频调速器后，实现了电机的软启动，延长了电机的寿命，也减少了风道的振动与磨损，特别是在低负荷时更为显著，具有良好的节能效果和实用价值。     

THE CALCULATING TEMPERATURE OF THERMAL CHARACTERISTICS OF NATURAL VENTILATION FOR A COLD FRUIT STORAGE DBTERMINATION

The paper analyzes the thermal characteristics of a natural ventilation cold stor-age,It shows that the calculating temperature in or outside the room is mainly effected by atmo-spheric temperature and the calculating temperature for a cold storage. They are determined by thelocal meteorological parameters.