Translational Physiology Block 5 Flashcards
What are features of COPD?
prolonged expiratory phase (decreased FEV1/FVC), wheezing, increased chest diameter (barrel and breath at higher lung volumes), increased residual volume (air trapping; increased functional residual capacity); decreased elasticity (emphysema), increased airway resistance (bronchitis; decrease in airflow); a cough that produces mucus; reduced mechanical tethering
What is normal FEV1/FVC ratio?
0.8 (in first second of expiration)
What are the causes of COPD?
Alpha-1-Antitrypson Deficiency (anti inflammatory against neutrophil elastases); smoking
What are the features of fibrosis?
decreases residual volume, decreased total lung capacity and decreased functional residual capacity; decreased lung compliance (greater effort needed); normal or elevated FEV1/FVC; rapid shallow breaths
Describe asthma.
two forms (intrinsic: exercise and stress; extrinsic: allergens); airways become constricted; can be treated with broncho-dilators and anti-inflammatory agents
What are the five causes of hyoxemia?
shunt, V/Q mismatch, inspired air, hypoventilation, and diffusing capacity of the lung (fibrosis)
What is pneumonia? is it restrictive or obstructive?
inflammation of the lung caused by infection with bacteria, viruses, and other organisms; restrictive
Describe the fetal circulation.
blood enters from the umbilical vein and is shunted by the ductus venosus to the inferior vena cava; blood may then be shunted from the right atrium to the left atrium via the foramen ovale; some blood may enter the right ventricle and is shunted from the the pulmonary artery to the aorta via the ductus arteriosus
How does pulmonary circulation change from fetus to birth?
in the fetus, the circulation is not patent (hypoxic vasoconstriction; very high pressures that are greater than the systemic circulation); following birth, the baby may inspire air which opens up the vessels and results in closing of the ducts (resistance and pressure profiles changes to a low pressure system)
What are key events in the development of the baby lung? what complications may arise?
resorption of fluid, pulmonary vasorelaxation, and continuous breathing; hyperoxia, apnea, and volutrauma (alveolar distension with mechanical ventilation)
Describe neonatal respiratory distress syndrome.
affects premature babies; atelectasis (collapse of alveoli); hypoxemia, hypercapnia (carbia); V/Q mismatch; hypoventilation
Surfactant has a greater effect on smaller or larger alveoli?
smaller
What should not be given to a patient with respiratory distress syndrome?
oxygen which may cause oxidative stress
How is respiratory distress syndrome treated?
exogenous surfactant, endotracheal tube, CPAP device; glucocorticoids (stimulates resorption of fluid if there is an infection)
What are features of chronic neonatal lung injury?
(seen at later ages); decreased FEV1 and increased incidence of asthma; etiology: oxidative stress, mechanical stress, or infection causing remodeling of the lung and altered vasculature
Describe a positive pressure ventilator.
gas tank with an attached humidifier and pump; two different gas lines close to the body to avoid increased dead-space; soda lime to dilute the expired carbon dioxide
Why would a patient need a ventilator?
decreased ventilation caused by CNS depression, structural lung injury, or neuromuscular disease; hypoxemia
What are the goals of a ventilator?
increase ventilation (primarily for hypoventilation), restore tidal volume, restore FRC; decrease demand on respiratory muscles; supply necessary oxygen
What is the importance of extrinsic PEEP?
Setting a PEEP prevents lungs from continuously collapsing and re-expanding (limiting injury); decreased effort needed for breathing; recruitment of collapsed alveoli
Are settings with higher or lower tidal volumes better for the health of the patient?
lower
What settings are important in treating a patient with COPD on a ventilator?
reducing auto-peep (prevent air trapping); maximizing respiratory rate (slow); maintain patients lung volumes at midpoint (high compliance)
What is optimal PEEP in respiratory distress syndrome?
lower inflection point just above alveolar collapse (+ pressure controlled ventilation to prevent volutrauma)