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resp 184 wkbk 1
workbook chapter 1 Basic Terms and Concepts of Mechanical Ventilation
| Question | Answer |
|---|---|
| Describe the difference between ventilation and respiration | Ventilation refers to the movement of gas into and out of the lungs. Respiration is the movement of gas molecules across a cell membrane. |
| The movement of oxygen and carbon dioxide in and out of the alveolar capillaries is known as what? | External respiration |
| The movement of oxygen and carbon dioxide in and out of body tissue is called what | Internal respiration |
| Describe the conditions necessary for air to flow from point A to point B in Figure 1 1 | The pressure at point A needs to be higher than the pressure at point be to create a pressure gradient |
| The pressure in the potential space between the parietal and visceral pleura is known as what | Intrapleural pressure |
| At the end of exhalation during spontaneous breathing intrapleural pressure is approximately what | -5 centimeters h2o |
| At the end of inspiration intrapleural pressure is approximately | -10 centimeters h2o |
| P awo | Airway opening pressure |
| P a w | Airway pressure |
| Pbs | Body surface pressure |
| Pa | Alveolar pressure |
| Ppl | Intrapleural pressure |
| Name at least three additional terms for airway opening pressure | Mouth pressure Pm, airway opening pressure Paw, proximal airway pressure, mask pressure. |
| How is intrapleural pressure estimated? | Intrapleural pressure is estimated using the esophageal pressure. P e s is obtained by placing a balloon in the esophagus and monitoring pressure changes in the balloon |
| The pressure gradient between airway pressure and alveolar pressure is known as what? | Trans airway pressure |
| Trans airway pressure is responsible for the movement of air in the what? | Conductive airways |
| Trans airway pressure gradient is calculated by the formula | Pta = P a w minus P a |
| The pressure needed to expand or contract both of the lungs and the chest wall at the same time is known as what? | Transthoracic pressure PW |
| Transthoracic pressure gradient is calculated by what formula? | Pw=P a minus Pbs |
| The pressure that is responsible for maintaining alveolar inflation is known as | Trans pulmonary pressure p l |
| Tran pulmonary pressure is calculated by what formula? | P l = P a minus Ppl |
| The pressure that is required for inflation of the lungs and airways during positive pressure ventilation is called | Trans respiratory pressure |
| Trans respiratory pressure is calculated by what formula? | Ptr=P a minus Pbs |
| What pressure gradient is represented by airway opening pressure to body surface pressure? | Trans respiratory pressure |
| What is the function of Tran Respiratory pressure? | Trans respiratory pressure is the pressure required to inflate the lungs and airways during positive pressure ventilation |
| what is the pressure gradient represented by body surface pressure to alveolar pressure? | transthoracic pressure |
| What is the function of transthoracic pressure during breathing? | the pressure needed to expand or contract the lungs and chest wall at the same time |
| What is the pressure gradient between alveolar pressure and intrapleural pressure? | Trans pulmonary pressure |
| What is the function of Tran pulmonary pressure during breathing | The pressure required to maintain alveolar inflation |
| What is the pressure gradient represented by airway pressure to alveolar pressure | Trans airway pressure |
| What is the function of trans airway pressure | It is the pressure needed to overcome airway resistance or to cause movement in the conduct of an Airways |
| Describe how a negative pressure ventilator causes air to move into an individual's lungs. | Body in airtight container at less than atmospheric pressure. negative pressure transmitted across chest wall into intra-alveolar space. Trans airway pressure gradient causes air to move into the lungs |
| List three advantages of using negative pressure ventilators. | No artificial airway required, patients able to eat and speak, fewer physiological disadvantages than positive pressure ventilation |
| Calculate the trans airway pressure when the mouth pressure is + 25 centimeters h2o Andy intra-alveolar pressure is + 5 centimeters h2o | 25 centimeters h2o minus 5 centimeters h2o equals 20 centimeters h2o |
| The highest pressure recorded at the end of inspiration is called what? | Peak inspiratory pressure or peak airway pressure |
| The pressure at which expiration ends is called what? | Baseline pressure |
| When end expiratory pressure is above atmospheric pressure this is called what? | Positive end-expiratory pressure peep |
| The pressure required to overcome the elastic recoil of the lungs is known as what? | Plateau pressure |
| How is plateau pressure measured on a mechanically ventilated person? | By selecting inspiratory pause or inflation hold maneuver. |
| What are the two types of forces that oppose inflation of the lungs? | Elastic and frictional forces |
| The relative ease with which a structure distend is known as what? | Compliance. |
| The tendency of a structure to return to its original form after being stressed is known as what? | Elastance |
| Pulmonary compliance is defined as what? | The change in volume that corresponds to the change in pressure. C=âV/âP |
| Normally total compliance of the lungs and thorax is about how much? | 0.1 L/cm H2O or 100 mL/cm H2O |
| total lung compliance can range from | 0.05 L/cm H2O to 0.17 L/cm H2O |
| While being mechanically ventilated, the compliance of value for a male with normal lungs is | 40 to 50 milliliters per centimeter h2o |
| While being mechanically ventilated, the compliance of value for a female with normal lungs is | 35 to 45 mL/cm H2O |
| What is the formula to calculate static compliance? | Cstat = the change in volume divided by plateau pressure minus end expiratory pressure. change V/ (P plateau- EEP) |
| 28. When more pressure is required to deliver a specific volume, what is happening to compliance? | the lung compliance is decreasing. |
| 29. Calculate static compliance when plateau pressure is 27cm H2O, baseline pressure is 10cm H2O, and tidal volume is 750 mL. | Cstat = 750 mL / (27 - 10 cm H2O) = 44 mL/cm H2O. |
| 30. Calculate static compliance when plateau pressure is 35 cm H2O, baseline pressure is 5 cm H2O, and tidal volume is 575 mL. | Cstat = 575 mL / (35 - 5 cm H2O) = 19 mL/cm H2O |
| 31. Calculate static compliance when plateau pressure is 18 cm H2O, baseline pressure is 0 H2O, and tidal volume is 650mL. | Cstat = 650 mL / (18 - 0cm H2O) = 36mL/cm H2O |
| 32. What happens to peak inspiratory pressures as the lungs become harder to ventilate? | 32. As the lungs become harder to ventilate, PIP will increase. |
| 32. What happens to lung compliance as the lungs become harder to ventilate? | 32. As the lungs become harder to ventilate, lung compliance will decrease |
| 33. Define resistance. | 33. Resistance is defined as frictional forces associated with ventilation. |
| 34, What is the formula for airway resistance (Raw)? | 34. Raw = (PIP – Pplateau) ÷ Flow (L/sec) |
| 35. What is the normal resistance range for flow rates of 0.5L/sec? | 35. At flow rates of 0.5 L/sec, Raw is 0.6 to 2.4 cm H2O/L/sec. |
| 36, What lung disease causes both airway resistance and static compliance to increase? | 36. Emphysema can cause increased compliance due to tissue destruction and loss of elastic recoil. It also can cause airway resistance due to airway inflammation, small airway obstruction, and bronchospasm. |
| 37. Calculate the transairway pressure (Pta) when PIP is 27 cm H2O and P plateau is 20 cm H2O. | 37. PTA = PIP − Pplateau 27 cm H2O – 20 cm H2O = 7 cm H2O |
| 38. How much pressure is needed to overcome airway resistance when PIP is 30 cm H2O and P plateau is 20 cm H2O? | 38. The amount of pressure needed to overcome airway resistance or the amount of pressure lost to airway resistance is equal to the transairway pressure. PTA = 30 cm H2O – 20 cm H2O = 10 cm H2O |
| 39. What is the normal amount of pressure lost to airway resistance when a patient has a properly sized endotracheal tube? | 39. 5 cm H2O |
| 40. Calculate airway resistance for a ventilated patient with the following: PIP 48cm H2O, P plateau 30cm H2O, and a set flow rate of 40L/minute. | 40. Raw = (PIP – Pplateau) ÷ Flow (L/sec) = (48 – 30 cm H2O) ÷ (40 L ÷ 60 sec) = 18 cm H2O ÷ 0.67L/sec Raw = 27 cm H2O/L/sec |
| 41. Calculate airway resistance for a ventilated patient with the followint: PIP 25cm H2O, P plateau 15cm H2O, and a set flow rate of 60L/minute. | 41. Flow rate of 60 L/min = 1 L/sec; Raw = (25 – 15 cm H2O) ÷ 1 L/sec Raw = 10 cm H2O/L/sec |
| 42. Why are the characteristics of the lung not homogeneous? | 42. The characteristics of the lung are not homogeneous, because each acinus may have entirely different values for compliance and resistance. |
| 43. Compare the filling time and volume for a normal lung unit, a low compliance unit, and a unit with high airway resistance using the same driving pressure. | A low compliance = less volume than a normal unit;it fills and empties more rapidly. high airway resistance fills slowly and takes longer to empty than a normal. The faster the respiratory rate, the less volume enters a unit with high airway resistance. |
| 44. What factors contribute to resistance to breathing? | 44. The movement of structures, including the lungs, abdominal organs, rib cage, and diaphragm; gas viscosity; gas density; the length and diameter of the airways; and the flow rate of the gas are all factors that contribute to airway resistance. |
| 45. What clinical factors can increase airway resistance by decreasing the radius of the airways? | 45. Clinical factors that contribute to airway resistance include bronchospasm, airway secretions, mucosal edema, small endotracheal tubes, and airway inflammation. |
| 46. How many seconds will it take to allow 86% of the tidal volume to be exhaled when compliance is 25mL/cm H2O, P plateau is 24cm H2O, flow rate is 60L/min, with no PEEP. | 46. CSTAT × Raw = Time constant; 25 mL/cm H2O = 0.025 L/cm H2O; 0.025 L/cm H2O × 30 cm H2O/L/sec = 0.75 sec |
| 47. Calculate the time constant for a mechanically ventilated patient when the tidal volume is 600mL, PIP is 30cm H2O, P plateau is 24cm H2O, flow rate is 60L/min, with no PEEP. | anki |
| 48. What percentage of passive filling occurs for 1, 2, 3, 4, and 5 time constants? | 48. 1—63%, 2—86%, 3—95%, 4—98%, 5—100% |
| 49. The time constant for patient #1 is 0.05 seconds; patient #2 is 3 seconds; and 0.5 seconds for patient #3. If the same filling pressure is used for each, which patient will recieve the most volume during inspiration and why? | Anki full answer, 49. The time constant for patient 1 is very short, meaning that this patient’s lungs are noncompliant, or stiff. Patient 1 would receive less volume than normal lungs. The time constant for patient 2 is very long, meaning that there is i |
| 50. Calculate the time constant for a compliance of 55mL/cm H2O and resistance of 6cm H2O/L/sec. | 50. 0.055 L/cm H2O × 6 cm H2O/L/sec = 0.33 second |
| 51. What is the inspiratory time setting to allow 95% volume emptying for a patient with the time constant calculated in question 50? | 51. The third time constant will have 95% of the volume emptied. Therefore, 0.33 × 3 = 0.99 second. |
| 52. Why do patients with increased airway resistance develop air trapping with high set ventilator rates? | They have longer time constants and lungs take longer to fill and empty. Rapid respers reduce the expiratory time, The patient is unable to exhale fully. This incomplete emptying of the lungs increases the FRC (air-trapping) and causes auto PEEP. |
| 53. Calculate the time constant for a mechanically ventilated patient when the tidal volume is 700 mL, PIP is 45cm H2O, P plateau is 18cm H2O, flow rate is 60L/min, and PEEP 5cm H2O. | 53. CSTAT = 0.7 L ÷ (18 – 5 cm H2O) = 0.054 L/cm H2O Raw = (45 – 18 cm H2O) ÷ (60 L ÷ 60 sec) = 27 cm H2O/L/sec Time constant = 0.054 L/cm H2O × 27 cm H2O/L/sec = 1.46 seconds |
| 54. anki | anki |
| 55. anki | anki |
| Critical Thinking Questions | |
| 1. When the PIP is 43cm H2O and the P plateau is 18 cm H2O, how much pressure was required to overcome the resistance of the airways? | PIP the amount of pressure required to overcome both the resistance of the airways and the elastic resistance of the alveoli and ventilator circuitry. PIP - Pplateau = the amount required to overcome airway resistance; in this case: 43 – 18 = 25 cm H2O. |
| 2. What time constants would you expect for a patient with adult respiratory distress syndrome? | 2. Acute respiratory distress syndrome causes lung compliance to decrease, which shortens time constants. |
| 3. Describe how emphysema causes lung units to have long time constants. | Emphysema is characterized by dilation and destruction of lung units from the terminal bronchioles to the alveoli. This causes loss of elastic recoil increasing lung compliance.lengthens the fill and empty time, is represented by a long time constant. |
| 4. What time constants would you expect for a 30-week (gestational age) premature infant? | 4. At 30 weeks of gestation, there is a high risk for developing respiratory distress syndrome because of pulmonary immaturity. Insufficient pulmonary surfactant production leads to low lung compliance and thus short time constants. |
| case studies in anki | |
| NBRC style questions | |
| 1. Calculate the static effective compliance during the delivery of a ventilator breath with 650 mL, with a P plateau of 28cm H2O. a. 0.04cm H2O/L b. 0.23 L/cm H2O c. 23 mL/cm H2O d. Not enough information is given. | c. 23 mL/cm H2O |
| 2. Calculate the airway resistance for a patient receiving mechanical ventilation with a set tidal volume of 825 mL and a peak flow setting of 50L/min when the teak inspiratory pressure is 46cm H2O and the P plateau is 22cm H2O. | C. 28.9 cm H2O/L/sec |
| 3. Calculate one time constant for the following data: Peak inspiratory pressure: 29 cm H2O P plateau: 23cm H2O Tidal volume: 600mL PEEP: 5cm H2O Inspiratory flow rate: 45L/min | d. 0.27 seconds |
| 4. The cause fo a mechanically ventilated patient's peak inspiratory pressure to increase from 20 to 40cm H2O while the static compliance remains relatively unchanged is which of the following? | b. Increased airway resistance |
| 5. An increase in peak inspiratory pressure and P plateau with a stable transairway pressure may be caused by which of the following? | a. Acute respiratory distress syndrome |
| 6. Which of the following two will occur when a patient's lung-thoracic compliance improves? 1. P plateau decreases 2. Peak inspiratory pressure decreases 3. P plateau increases 4. Transairway pressure increases | 1. P plateau decreases 2. Peak inspiratory pressure decreases |
| 7. Over the course of several hours, a respiratory therapist has detected an increase in trans airway pressure of a mechanically ventilated patient. The patient's P plateau has remained stable. Which of the following may be the cause of this increase? | Fluid buildup in the peritoneal cavity. |
| 8. A patient's transairway pressure is rising, while the p plateau is constant. Which of the following should be done to correct this problem? | 1. Administer a bronchodilator. and 4. Suction airway secreations. |
| 9. Calculate the static compliance for a patient who is being mechanically ventilated and has an exhaled tidal volume of 825mL, P plateau of 47cm H2O, and PEEP of 8cm H2O. | C. 21 mL/cm H2O. |
| 10 Which of the following situations will demonstrate the highest airway resistance? | PIP is 52cm H2O, P plateau is 18 cm H2O, flow rate is 45 L/min |
| Key Terms Crossword Puzzle | |
| An alternate term for pressure in the airways of the lungs (three words) | Proximal airway pressure |
| The total amount of gas remaining in the lungs after a resting expiration (three words) | Functional residual capacity |
| Abbreviation for a form of ventilatory support characterized by rates up to 4000 breaths/minute | HFOV |
| The pressure measurement when there is no gas flow | plateau |
| pressure measured in the esophagus that is used to represent intrapleural pressure (two words) | esophageal pressure |
| the movement of oxygen into cells and the movement of carbon dioxide out of cells (two words) | internal respiration |
| The measurement of elastic forces that oppose lung inflation two words | Static compliance |
| Pressure in the airways of the lungs to words | Airway pressure |
| Another term for auto PEEP hyphenated word | Auto PEEP |
| The impedance of gas flow through the conductive airways | Resistance |
| A deliberate increase in the ventilators bassline pressure 2 words | Extrinsic peep |
| The movement of gas molecules across a membrane | Respiration |
| Pressure measured at the mouth three words | Airway opening pressure |
| Abbreviation for the ventilation using small pulses of pressurized gas at rates between 100 and 400 breaths per minute | HFJV |
| A complication of positive pressure ventilation that causes an inadvertent buildup of positive pressure in the alveoli. 2 words | Intrinsic peep |
| Abbreviation for ventilation using lower than normal tidal volumes and respiratory rates between 60 and 100 breaths per minute | HFPPV |
| The pressure between the alveolus and the pleural space responsible for maintaining alveolar inflation 3 words | Alveolar distending pressure |
| Another term for the highest pressure recorded at the end of inspiration three words | Peak inspiratory pressure |
| Airway communications between the Lung and pleural space | Bronchopleural fistulas |
| The highest pressure recorded at the end of inspiration | Peak airway pressure |
| The ease with which the lungs distend | compliance |
| The movement of oxygen into the bloodstream and carbon dioxide out of the blood stream. Two words | External respiration |
| The movement of air into the lungs for gas exchange and out of the lungs for carbon dioxide removal | Ventilation |
| A functional unit of the lung | Acinus |
| A mathematical expression used to describe the filling and emptying of lung units. Two words | time constant |
| The difference between an area of high pressure and low pressure | Gradient |
Created by:
johndreamer