Gas exchange

Oxygen intake for respiration, also carbon dioxide and, generally, ammonia elimination takes place across gas-exchange surfaces, usually the gills in fish. Water flows across gills, separated by the pharyngeal gill clefts, and supported by gill arches, and which possess highly folded surfaces covered by a very thin epithelium. Blood flow and water flow are separated only by the epithelium with a ‘countercurrent’ gas exchange between the two. A respiratory centre in the hind-brain is a respiratory rhythm pacemaker for the oral and pharyngeal ventilation movements creating water flow across the gills, although ‘ram ventilation’ occurs without such movements. The oxygen and carbon dioxide-carrying capacity of blood is increased considerably by temporary attachment to haemoglobin pigment in the erythrocytes. Some fish are air breathing, using lungs, swim bladder, skin or lips for gaseous exchange. Hypoxia, hypercapnia, supersaturation and high water temperatures present problems for fish respiration, which are discussed.

The Effect of Mechanical Ventilation on TASK-1 Expression in the Brain in a Rat Model

Background and Objective. TWIK-related acid-sensitive potassium channel 1 (TASK-1) is closely related to respiratory central control and neuronal injury. We investigated the effect of MV on TASK-1’s functions and explored the mechanism using a rat model.Methods. Male Sprague-Dawley rats were randomized to three groups:(1)high tidal volume (HVt): MV for four hours with Vt at 10 mL/kg;(2)low Vt (LVt): MV for four hours with Vt at 5 mL/kg;(3)basal (BAS): anesthetized and unventilated animals. We measured lung histology and plasma and brain levels of proteins (IL-6, TNF-α, and S-100B) and determined TASK-1 levels in rat brainstems as a marker of respiratory centre activity.Results. The LISs (lung injury scores) were significantly higher in the HVt group. Brain inflammatory cytokines levels were different to those in serum. TASK-1 levels were significantly lower in the MV groups (P=0.002) and the HVt group tended to have a lower level of TASK-1 than the LVt group.Conclusion. MV causes not only lung injury, but also brain injury. MV affects the regulation of the respiratory centre, perhaps causing damage to it. Inflammation is probably not the main mechanism of ventilator-related brain injury.

Clinical Efficacy of Treatment of Children with Bronchial Asthma, Population in Remote Areas in Terms of Regional Respiratory Centre as Sanatorium Type: Work Results for 10 Years

The purpose of this work is to improve the specialized medical care for children with bronchial asthma, people living in remote areas and villages. Materials and methods: The study involved 1,024 children with asthma (solid sample, 2003) which were observed in period of 2003 to 2013. There are 391 children-villagers as the main group; clinical examination was carried out by district pediatrician and 633 children as regional city residents (the comparison group); clinical examination was carried out by district pediatrician together with pulmonologist or allergist. The author used the methods of observation (solid documentary and selective, current, prospective) and the method of expert evaluations. Results: a significant discrepancy (p=0,03) in the evaluation by district pediatrician, practitioner or family doctor) of severity bronchial asthma and absence of bronchial asthma treatment in 28% of patients of the main group has been demonstrated in 2003. The discrepancy in the diagnosis of bronchial asthma of light degree and medium severe degree (p=0.03) were detected by a positively accepted method (examination of pulmonologist/allergist, clinical and instrumental examination, 2008). Clinical efficacy of treatment of children with bronchial asthma as residents in regional respiratory centre has been proven. For ten years the number of children with BA decreased by 25%, the number of bronchial asthma patients with moderate current (p=0.03) decreased and the number of patients with medium severe degree bronchial asthma (p=0.01) significantly increased. In 2013, the patients of the main group observations received adequate basic therapy bronchial asthma; number of children with asthma decreased in 2 times (p=0.03); the calls in the ambulance and the need for hospitalization decreased more than 2 times (p=0.03); the number of children with controlled bronchial asthma increased from 26 to 64% (p=0.05).