physiology & pathophysiology of respiration, mvdr i

uhrikova phd

physiology – what is essential for breathing?

1.pulmonary ventilation (athmosphere – alveoli)

2.diffusion (alveoli – blood)3.transport of gases (blood –

tissues)4.(regulation)

what is essential for breathing

1. pulmonary ventilation (athmosphere – alveoli)– muscles – pressure in thoracic cavity – lung compliance– thorax compliance– pulmonary volume– alveolar ventilation

impaired pulmonary ventilation

PLEURAL EFFUSION•normally 0.1-0.3 ml/kg of fluid•communication between left & right pleural space (?)

•inflammatory vs non-inflammatory effusion

impaired pulmonary ventilation

PLEURAL EFFUSION•normally 0.1-0.3 ml/kg of fluid•communication between left & right pleural space (?)

•inflammatory vs non-inflammatory effusion

impaired pulmonary ventilation

PLEURAL EFFUSION•normally 0.1-0.3 ml/kg of fluid•communication between left & right pleural space (?)

•inflammatory vs non-inflammatory effusion

impaired pulmonary ventilation

PLEURAL EFFUSION•normally 0.1-0.3 ml/kg of fluid•communication between left & right pleural space (?)

•inflammatory vs non-inflammatory effusion

impaired pulmonary ventilation

PLEURAL EFFUSION•normally 0.1-0.3 ml/kg of fluid•communication between left & right pleural space (?)

•inflammatory vs non-inflammatory effusion

impaired pulmonary ventilation

PLEURAL EFFUSION•transudate•modified transudate

•hemorrhage•bile•chyle•septic exudate (pyothorax)•aseptic exudate (neoplasia, FIP)

¼ Hct

Bie>Bis

milky

what is essential for breathing

2. diffusion (alveoli - blood)– composition of gases in alveoli– diffusion capacity of the alveolar

membrane– pressure of blood in the pulmonary

vessels– amount of the blood in systemic vs

pulmonary circulation– distribution of the blood according to

ventilation

impaired diffusion

PULMONARY EMBOLISM

•fq of small emboli probably high•arise from deep vein thrombosis of the lower extremities

•mechanism in thrombi formation:– stasis of blood– alteration in coagulation– alteration of vessel wall

impaired diffusion

PULMONARY EMBOLISM

•most commonly cardiomyopathy in cats•heartworm disease in dogs

impaired diffusion

PULMONARY EMBOLISM

•pulmonary hemodynamics:thrombi + reflective vasoconstriction increase in pulmonary artery pressure

right-ventricle heart failure(pulmonary oedema) obstruction

of at least ½ of

pulmonary circulation

impaired diffusion

PULMONARY EMBOLISM

•pulmonary mechanics:decreased alveolar pCO2

bronchoconstriction + alveolar duct constriciton

increase in pulmonary resistance

impaired diffusion

PULMONARY EMBOLISM

•gas exchange:ventilation-perfusion inhomogeneity

increased dead space

impaired diffusion

PULMONARY EDEMA

•accumulation of fluid in extravascular tissue•two phases

– interstitial edema– alveolar edema alveoli

impaired diffusion

PULMONARY EDEMA

•interstitial edema increases alveolar-capillary thickness by 15-20 %

- fluid moves from gas-exchange site to perivascular site – remains unaffected unless- when interstitial space expands >50 % alveolar edema occurs

impaired diffusion

PULMONARY EDEMA

•alveolar edema– leakage site: junction between alveoli &

small alveolar ducts OR epithelial tight junctions

impaired diffusion

PULMONARY EDEMA

•decrease in lung compliance•decrease in pO2•further progress in lung compliance

impaired diffusion

PULMONARY EDEMA

•most commonlyleft sided heart failure

( hydrostatic pressure)may be without alveolar edema due

to adjustment of the lymphatic drainage

impaired diffusion

PULMONARY EDEMA

•most commonlyexcessive i.v. fluids, acute renal failure

( hydrostatic pressure permeability)

toxins (endotoxin, exotoxins)( permeability)

lymphatic drainage

what is essential for breathing

3. transport (blood - tissues)– haemoglobin content

what is essential for breathing

3. transport (blood - tissues)

what is essential for breathing

4. regulation– respiratory center– peripheral receptors

impaired regulation

IVERMECTIN TOXICOSIS•border collie, australian shepherd, collies, long-haired whipet, etc.•ivermectin cross hematoencephalic barrier•stimulate GABA release•ataxy, mydriasis, hypersalivation, vomiting, blindness, tremor, seizures, bradykardia, bradypnoe

diagnostics• pulse oxymetry• arterial blood gases• capnography• plethysmograph

thank you for attention

referencesCohn LA, Reinero CR. Respiratory defense in health and disease. Vet Clin North Am Small Anim Pract 2007; 37: 845-860.Dunlop RH, Malbert CH. Veterinary patophysiology. Blackwell publishing 2004, Iowa, USA.Epstein SE. Exudative pleural disease in small animals. Vet Clin Small Anim 2014; 44:161-180.Guyton AC, Hall JE. Textbook of medical physiology. Elsevier 2006, Pennsylvania, USA.Hoffman A. Airway physiology and clinical testing. Vet Clin North Am Small Anim Pract 2007; 37: 829-843.