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Mech/Vent Unit 2
SPC Mechanical Ventilation Unit 2 Exam 1
Question | Answer |
---|---|
What is Ventilation? | The volume of air inspired per minute. Ventilation rate of humans is 4-5L/min. |
What is Perfusion? | The bulk flow of blood from the right ventricle to pulmonary capillaries (through the pulmonary arteries) and back to the left atrium (through the pulmonary veins). Perfusion rate is about 5L/min. |
What is deadspace? | Ventilation without Perfusion |
What is an example of deadspace? | Pulmonary Emboli |
What is Pulmonary Shunt? | Perfusion without Ventilation |
What are examples of Pulmonary Shunt? | Atelectasis, pneumonia, ARDS |
What is Normal Unit? | Ventilation matches Perfusion Ideally 1.0 but normally 0.8 |
What is Silent Unit? | No Ventilation & No Perfusion |
The A-A O2 Gradient is also know as what? | Alveolar-Arterial O2 Gradient |
What ratio has to do with the A-A Gradient? | PaO2/FIO2 |
What ratio of PaO2/FIO2 is considered normal? | >200 mmHg |
What ratio of PaO2/FIO2 is considered severe oxygenation? | <200 mmHg |
What does PaO2 stand for? | Partial Pressure of Arterial O2 |
What does PAO2 stand for? | Partial Pressure of Alveolar O2 |
What is the normal range for the PaO2/PAO2 ratio? | 0.75-0.95 or 75%-95% |
What percent is considered poor oxygenation transfer and increased shunting in calculating PaO2/PAO2? | 30% |
What percent is considered critical in calculating PaO2/PAO2? | 15% or less |
What is Responsive Hypoxemia? | Hypoxemia that has a significant response to an increase in FIO2 simply due to V/Q mismatch |
What is Refractory Hypoxemia? | Hypoxemia that does not respond to an increase in FIO2 due to combination of anatomic and capillary shunting |
What is the equation for Physiologic Dead space? | Anatomic + Alveolar = Physiologic Dead space |
What is the abbreviation for Anatomical Dead space? | (VD anat) |
What is the abbreviation for Alveolar Dead Space? | (VD alv) |
What is the abbreviation for Mechanical Dead Space? | (VD mech) |
What is Anatomical Dead Space? | Gas Volume in the conducting airways |
What is Alveolar Dead Space? | Gas which DOES NOT reach functioning gas exchange |
What is Mechanical Dead Space? | Re-breathed gas from mechanical attachments like tubing |
What does PECO2 stand for? | Partial Pressure of Exhaled O2 |
Exhaled O2 can be collected in what? | Douglas Bag or Capnometry |
What is the Normal Value for PECO2? | 28 mmHg |
VD/VT is an abbreviation for what? | Dead Space Ventilation per Breath |
What formula is used to calculate VD/VT? | (PaCO2-PECO2)/PaCO2 |
What is the normal range for VD/VT? | 20%-40% |
What percentage of VD/VT is incompatible with spontaneous respiration? | >80% |
Mechanically Ventilatted patients usually have what VD/VT? | 50% or greater |
What other patients may have a high VD/VT? | Pulmonary Embolus patients |
What is the abbreviation for Alveolar Ventilation? | (VA) |
What is the formula for (VD) Dead Space Volume? | VT x (VD/VT) = VD |
What is the formula for (VA) Alveolar Ventilation? | (VT-VD)f = VA |
What is Lung Compliance? | Stretch ability of lung tissue |
What is Thoracic Compliance? | Stretch ability of the chest wall |
What is Total Compliance? | The sum of the reciprocals of both lung and thoracic compliance |
What is normal (CL) Lung Compliance? | 200 ml/cm H2O or 0.2 L/cm H2O |
What is normal (CC) Thoracic Compliance? | |
What is the formula for Total Compliance (CT)? | 1/CL + 1/CC = 1/CT |
What is Static Compliance? | Compliance measured at a point of no airflow |
What is Dynamic Compliance? | Compliance measured during airflow |
What is the compliance formula for Static and Dynamic compliance? | (Volume/Pressure) or (Liters/cmH2O) or (ml/cmH2O) |
What is the normal range for static and dynamic compliance? | |
What is the Static Compliance Calculation? | Volume delivered by Ventilator/(Static Airway Pressure - Baseline Pressure) |
What is the Static Compliance Calculation? | Volume delivered by Ventilator/(Peak Airway Pressure - Baseline Pressure) |
What does PIP stand for? | Peak Inspiratory Pressure |
What does PEEP stand for? | Positive End-Expiratory Pressure |
What 5 factors that alter compliance? | 1. Congestion (congestive heart failure, pulmonary edema) 2. Atelectasis 3. Fibrosis (scar tissue in the lung) 4. Pneumonia 5. Emphysema (Floppy lungs are very compliant) |
What 6 factors alters Thoracic Compliance (chest wall) outside the lung? | 1. Kyphoscoliosis (severe curvature of the spine) 2. Pectus Excavatum (sunken chest with depressed sternum) 3. Ascites (Excess fluid in the gut) 4. Obesity (Pickwickian Syndrome) 5. Chest Strapping 6. Diaphragmatic Impairment |
Static Compliance will be altered by changes in what? | Both Lung and Thoracic Compliance |
Dynamic Compliance will be altered by changed in what? | Both Lung and thoracic Compliance BUT also by changes in Airway Resistance |
What is Airway Resistance? | |
What is the abbreviation for Airway Resistance? | (Raw) |
What is the calculation for (RAW) Airway Resistance? | (RAW) = PIP - "P(Plateau)"/flow |
Conscious individuals will have a resistance of what? | 1-2 cmH2O per liter/sec |
Patients with obstructive disease with have resistance of what? | 13-18 cmH2O per liter/sec or more |
What is Tissue Resistance? | |
What 3 factors affect airway resistance? | 1. Types of gas flow 2. Nature of Airway 3. Airway Patency |
Smooth, Laminar flow results in what kind of resistance? | Low |
Rough, Turbulent flow results in what kind of resistance? | True |
Upper airways make what percentage of (Raw)? | 40-45% |
Narrow or curved airway results in what kind of resistance? | High |
Wide or straight airway results in what kind of resistance? | Low |
Patients with artificial airways i.e. ET Tubs or Tracheostomy will have resistance of what? | 5-7 cmH2O per liter/sec |
What is the normal range for pH of ABG? | 7.35-7.45 |
What is the normal range for PaCO2 of ABG? | 35-45 mmHg |
What is the normal range for PaO2 of ABG? | 80-100 mmHg |
What is the normal range for HCO3 of ABG? | 22-26 mEq/L |
What is the normal range for Base Excess of ABG? | -2 to +2 |
What is the relationship between changes in PaCO2 and pH? | When starting at a PaCO2 of 40mm Hg, for every 20 mm Hg increase in PaCO2 , the pH decreases by 0.10 units ALSO When the PaCO2 decreases by 10 mmHg, the pH increases by 0.10 units. |
What is a probable VENOUS sample? | pH 7.37, pCO2 47, pO2 41, HCO3 22, SaO2 75 or less |