quizlet 2

• During spontaneous ventilation, the diaphragm and other respiratory muscles create gas flow by


  Lowering the pleural, alveolar, and airway pressures. When pressures drop below atmospheric pressures, air flows into the lungs.
• What is positive pressure ventilation?

  Mechancial ventilation in which the volume is delivered by a positive pressure gradient (i.e., airway pressure higher than alveolar pressure).
• When negative pressure is used for ventilation, what happens to the pressures in the airways, alveoli, and pleura?

  It is decreased during inspiration
• What is pressure-controlled ventilation?

  Mode of ventilation in which a preset peak inspiratory pressure is used to provide ventilation. The delivered volume during this mode of ventilation is affected by the changing compliance and resistance.

  
  

  The tidal volume delivered to the lungs is directly related to positive pressure
• What is volume-controlled ventilation?

  Mode of ventilation in which a pre- set tidal volume is used to provide ventilation. The airway pressures during this mode of ventilation are affected by the changing compliance and resistance.

  
  

  The level of positive pressure ventilation is dependent on mechanical tidal volume.
• In PPV, what happens to the PIP and VT?

  It increases
• What is peak inspiratory pressure (PIP)?

  Maximum pressure measured during one respiratory cycle, usually at end-inspiration.

  
  

  Preset according to the estimated tidal volume requirement of the patient.
• What will happen to the Vt for a patient that has low lung compliance or high airway resistance on pressure controlled ventilation?

  Pt. may receive a smaller Vt when the preset pressure has been met.
• To avoid having the Pt. that has low lung compliance from getting too little Vt, what type of positive pressure ventilation would you use?

  Volume controlled ventilation
• For patients with low lung compliance, would you use a high or low PIP?

  High PIP
• For patients with high lung compliance, would you use a high or low PIP?

  Low PIP
• Peak inspiratory pressures reached too soon can be caused by

  Airway Obstruction

  Kinking of ET Tube

  Bronchospasm

  Low lung compliance

  Pressure limit set to low
• Unable to reach peak inspiratory pressure


  ET tube cuff leak

  Ventilator circuit leak
• What is the normal value for MAP?

  30 cmH2O
• What is mean airway pressure (mPaw)?

  Average pressure within the airway during one complete respiratory cycle. It is directly related to the inspiratory time, respiratory frequency, peak inspiratory pres- sure, and positive end-expiratory pressure (PEEP).
• To keep mPaw at it lowest level


  I Time, Frequency, PIP, PEEP must be kept as low as possible .
• In lungs with normal lung compliance, about how much airway pressure is transmitted to the thoracic cavity?

  50%
• For patients with low lung compliance, how would set the PIP and PEEP?

  It needs to be set at a higher rate to ventilate and oxygenate the patient.
• What happens to MAP when PPV is high?

  It increases
• What happens to cardiac output when PPV is high

  It decreases
• What is PEEP?


  It is an airway pressure strategy in ventilation that increases the end-expiratory or baseline airway pressure to

  a value greater than atmospheric pressure. It is used to treat refractory hypoxemia caused by intrapulmonary shunting.
• What is CPAP?


  The end- expiratory pressure applied to the airway of a spontaneously breathing patient.
• Difference between PEEP and CPAP?

  PEEP exerts a more negative effect on cardiac output and it raises the mPaw. PEEP can be detrimental to cardiac output because it is used in addition to positive pressure ventilation. Whereas CPAP, the pressure only includes positive airway pressure during spontaneous breathing.
• To lessen the detrimental effects of PEEP on cardiac output, what type of ventilation should you use instead?

  CPAP
• How does a decreased of venous return (filling of the ventricles) affect stroke volume and cardiac output?

  Both decreases
• An increase in positive airway pressure causes a higher intrathoracic pressure. In turn this pressure is transmitted to airways, alveoli, and great vessels. Compression of the vessels leads to


  Compression of the great vessels can lead to decreased venous return to the heart. A decreased venous return leads to a reduction of stroke volume and cardiac output.
• What is stroke volume?

  Blood volume delivered by one ventricular contraction
• What is oxygen delivery?

  Total amount of oxygen carried by the blood. It is the product of O2 content and cardiac output.
• What is pulsus paradoxus?

  Transient decrease of arterial blood pressure
• A significant reverse pulsus paradoxus (increase of systolic pressure 15 mm Hg) during positive pressure ventilation is a sensitive indicator of what?

  Hypovolemia
• What happens to blood pressure when PPV is high?

  It increases
• What happens to cardiac output and stroke volume when PAP is high?

  It decreases
• What happens to venous return when PAP is high?

  It decreases
• What happens to O2 delivery when PAP is high

  It decreases
• What happens to intrathoracic pressure when PAP is high?

  It increases
• What happens to Vt, Raw and Insp flow when PIP is high?

  It increases
• What happens to compliance when PIP is high?

  It decreases
• What happens to Vt, Raw and Insp flow when PIP is low?

  It decreases
• What happens to compliance when PIP is low?

  It increases
• What is thoracic pump mechanism?

  Alternations in pulmonary blood flow caused by changes in intrathoracic pressure during positive pressure ventilation. In hypotensive conditions, positive pressure ventilation decreases the blood flow to the left heart. In hypertensive conditions, this mechanism enhances the outflow of blood from the right ventricle and into the left heart.