pilbeams mechanical ventilation final exam.docx

spontaneous ventilation: - correct answer movement of air into and out of the lungs respiration: - correct answer exchange of o2 and co2 between an organism and its environment two components of respiration: Internal & External - correct answer 1. Internal: exchange of oxygen and carbon dioxide between systemic capillaries & the cells of the body. 2. External: diffusion of oxygen and carbon dioxide between the alveoli and pulmonary capillaries accessory muscles of inspiration: - correct answer scalene, sternocleidomastoid, pectoralis, trapezius accessory muscles of expiration: - correct answer internal & external oblique, rectus abdominus, transverse abdominal, serratus, latissimus dorsi what must exist for air to flow through the airway? - correct answer pressure gradient (i.e. air at one end of the tube must be higher than the other end) _____ _________ change as a result of gas flow into and out of the airways caused by a change in pressure gradient between the airway opening and alveoli. - correct answer lung volumes during spontaneous inspiration- - correct answer contraction of the inspiratory muscles cause enlargement of the thorax resulting in a decrease (more negative) in intrapleural and alveolar pressure. during a quiet expiration- - correct answer relaxation of the inspiratory muscles cause a decrease in thoracic volume (diaphragm & external intercostals return to their resting state) and an increase in alveolar pressure. at what point does bulk gas flow not occur because the pressures across the conductive airways are equal (i.e. there is no pressure gradient)? - correct answer there is no pressure gradient when the pressure at the airway opening and the pressure at the alveoli are the same, as occurs at the end of expiration 1 mm Hg= _______ cm H2O? - correct answer 1.36cm H2O 1 atm= ______ mm Hg= ______ cm H2O - correct answer 760mm Hg, 1034cm H2O Airway opening pressure (Pawo) is most often called mouth pressure (Pm) or airway pressure (Paw). Other terms that are often used to describe airway opening pressure include: - correct answer upper airway pressure, mask pressure, and proximal airway pressure. (unless pressure is applied at the airway opening, Pawo is zero or atmospheric pressure) intrapleural pressure (Ppl): - correct answer pressure in the potential space between the visceral and partial pleura. Ppl is normally about -5cm h20 at the end of expiration and about -10cm h20 at the end of inspiration. Ppl can be difficult to measure, so a related measurement is used, which is the esophageal pressure (Pes), which is obtained by- - correct answer placing a balloon in the esophagus; changes in the balloon pressure are used to estimate pressure and pressure changes in the pleural space. Transairway pressure (Pta): - correct answer airway pressure-alveolar pressure Transpulmonary pressure (PL) OR Transalveolar pressure (Ptp): - correct answer alveolar pressure-pleural pressure Transrespiratory pressure (Ptr): - correct answer airway opening pressure-body surface pressure Elastic force vs. Frictional force: - correct answer Elastic forces arise from the elastic properties of the lungs and chest wall; Frictional forces are the result of the resistance of the tissues and organs as they become displayed during breathing and the resistance to gas flow through the airways. Compliance (C) & Elastance (e): - correct answer C=the relative ease with which the structure distends; e= the tendency of a structure to return to its original form after being stretched or acted on by an outside force. Compliance formula: - correct answer change in volume/change in pressure for patients receiving mechanical ventilation, compliance measurement are made during static or no-flow conditions(e.g. this is the airway pressure measured at the end of inspiration; it is designated as the pplat). Thus these compliance measurements are referred to as: - correct answer static compliance or static effective compliance (Cs= Vt/(pplat-eep)) (eep is end expiratory pressure, which some clinicians call baseline pressure. when a patient is receiving peep, it is the eep value used in this calculation with static compliance) measurement of the frictional forces that must be overcome during breathing is referred to as: - correct answer resistance resistance formula: - correct answer Raw=(PIP-Pplat)/flow or, could see both ways- (Raw=Pta/flow) -Pta=pip-pplat Time constants (compliance x resistance) is a measure of how long the respiratory system takes to passively exhale (deflate) or inhale (inflate): time constants for 1sec-5secs= - correct answer 1=63.2% 2=86.5%