mechanical ventilation powerpoint presentation

Mechvent

1. Positive Pressure Ventilation

2. EFFECTS OF POSITIVE PRESSURE VENTILATION

3. Positive Pressure Ventilation Uses positive pressure to bring air into the lungs Can be used for both invasive and non invasive ventilation Also has 3 types: Volume type Pressure Type Pressure and Volume (Advance modes)

4. Relationship of Barometric Pressure and Alveolar Pressure during Spontaneous Breathing Spontaneous Breathing PB(cmH2O) PALV(cmH2O) ∆Pressure Flow Inspiration -5 -5 into lungs End-Inspiration none Expiration +5 +5 out of lungs End-expiration none

5. Relationship of Inspiratory Pressure and Alveolar Pressure during Positive Pressure Ventilation Spontaneous Breathing Pi(cmH2O) PALV(cmH2O) ∆Pressure Flow Inspiration 20 20 into lungs End-Inspiration 20 20 none Expiration 20 20 out of lungs End-expiration none

6. Airway Pressures Airway pressures such as: PAP, Pplat , mPaw = Vt , PFR, Raw Compliance have direct impact on: a. intrathoracic pressure b. blood flow c. blood pressure indirectly on major organs

7. Compliance Lungs with normal compliance - 50% of airway pressure is transmitted to the thoracic cavity. Lungs with low compliance - pressure transmitted to the thoracic cavity is much less due to dampening effect of nonelastic tissues. - for this reason the decrease in cardiac due to excessive PIP or PEEP is less severe

8. Cardiovascular Considerations Mean Airway Pressure and Cardiac Output PIP, I Time, RR, PEEP – shld be kept at minimum to keep mPaw at lowest possible level 2. Decrease in Cardiac Output and delivery O2 content x ↓ CO = ↓ O2 delivery 3. Blood Pressure Changes

9. Diagram of PPV leading to decrease in O2 Delivery PPV ↑ Intrathoracic Pressure Compression of Pulmonary Vessels and great vessels Reduction in stroke volume Reduction of Cardiac Output and Pulmonary bloodflow (High) V//Q mismatch Hypoxemia Decrease Oxygen Content Decrease in O2 delivery to the tissues

10. Cont… Blood Pressure Changes Pulsus Paradoxus : Spont breathing ↓ in systolic in asthma patient, cardiac tamponade > 10 mmHg Reverse Pulsus Paradoxus : Spont to PPV ↑ in systolic > 15 mmHg – hypovolemia note: PPV + PEEP may further lower cardiac output/ compromise cardiovascular functions in patients with cardiopulmonary disease.

11. Pulmonary Blood flow and Thoracic Pump mechanism PPV affects pulmonary blood flow entering and leaving the heart Hypotensive patients: ↑ in lung volume results in ↓pulmonary venous return to the Left ventricle Hypertensive Patients: ↑ in lung volume results in ↑pulmonary venous return to the Left ventricle due to: 1. compression of pulmonary blood vessel is minimal 2. due to thoracic pump mechanism - blood flow is enhanced during expiratory phase of PPV.

12. EFFECTS OF PPV ON HEMODYNAMIC MEASUREMENTS ↑ Intrathoracic Pressure ↓ Pulmonary blood Volume and ↑ systemic blood volume ↓ venous return (CVP) ↓ Right Ventricle stroke volume ↓ Pulmonary Artery Pressure (PAP) ↓ filling pressures (ventricles) ↓ Left ventricle stroke volume

13. Renal Considerations Eliminating waste, clearance of certain drugs, regulating fluid, electrolytes and acid-base balance Affected due to hypoperfusion Can lead to: 1. renal failure – urine output of < 400ml in 24 hours, ↑ BUN and Creatinine level

14. Hepatic Considerations Perfusion accounts for 15% of total CO Can lead to liver dysfunction - prothrombin (coagulation) time > 4 sec - bilirubin level level > 50mg/L - albumin < 20g/L Affects rate of drug clearance – increased concentration and prolonged drug effect

15. Abdominal Considerations ↑ Intraabdominal Pressure (IAP), due to: 1. bowel edema or obstruction 2. ascites 3. procedures such as: a. pneumatic anti shock garments b. surgical repair of abdominal hernia

16. Abdominal Considerations ↑ IAP (> 20 mmHg) + PPV + PEEP (>15 mmHg) can cause: 1. potentiation of pressures exerted on heart and blood vessels, leading to: a. cardiovascular dysfunction - ↓ CO b. renal dysfunction ↓ renal perfusion ↓ Glomerular filtration rate

17. Abdominal Considerations c. Pulmonary dysfunction ↓ FRC ↑ atelectasis impaired gas exchange ↑ V/Q/mismatch

18. Gastrointestinal Considerations Complications: Erosive esophagitis stress related mucosal damage (SRMD) diarrhea decreased bowel sound high gastric residual constipation

19. Gastrointestinal Considerations Complications are due to: 1. ↓ perfusion to GI tract 2. Medications used during MV

20. Nutritional Considerations malnutrition - are due to: frequent interuptions in enteral feeding > protein catabolism > loss of muscle performance > difficulty of weaning due to muscle weakness

21. Nutritional Considerations Diaphragmatic dysfunction - is due to: atrophy > cause by muscle proteolysis - leads to ↓ in muscle fiber content

22. Nutrition and Work of Breathing Total Parenteral Nutrition (TPN) or Hyperalimentation - a complete nutritional program provided to patients by any method other than intestinal route

23. Nutrition and Work of Breathing - hypertonic solution consisting of: Amino acids glucose vitamins electrolytes fat emulsion

24. Nutrition and Work of Breathing - shld keep dextrose ( carbo ) to a minimum > ↑ O2 consumption and CO2 production

25. Nutrition and Work of Breathing Fat based TPN > provide maximum caloric intake with minimum CO2 production > less WOB > patients with significant or persistent CO2 production

26. Neurologic Consideration Neurologic Changes in Hyperventilation Condition Pathophysiologic Changes Resp Alkalosis (<24 Hours) Decreased cerebral blood flow Reduced intracranial pressure Resp Alkalosis ( > 24 Hours) Left shift of oxyhemoglobin curve Increased O2 affinity for hemoglobin Reduced O2 releases to tissues Cerebral tissue hypoxia Neurologic dysfunction hypophosphatemia

27. Neurologic Consideration Neurologic Changes in Hypercapnia and hypoxemia Condition Pathophysiologic Changes Hypercapnia ( with normal pH) Increased cerebral blood flow increased intracranial pressure Hypercapnia ( with low pH) Impaired cerebral metabolism Hypoxemia Decreased mental and motor functions

28. Effects of Positive Pressure Ventilation

29. Characteristics of mechanical ventilators 1. Limits: a. Pressure limited b. volume limited 2. Breath delivered: a. mandatory breath b. assisted breath c. spontaneous breath

30. Characteristics of mechanical ventilators 3. Triggering: to inspiration a. Pressure triggered b. Flow triggered c. Time triggered

31. Characteristics of mechanical ventilators 4. Cycling: to expiration a. volume cycled b. pressure cycled c. flow cycled d. time cycled

32. Characteristics of mechanical ventilators 5. Variability: a. Pressure variable b. Volume variable

33. Positive Pressure Ventilation Volume Ventilation

34. Volume Ventilation CHARACTERISTICS: Volume limited or volume pre – set Volume cycled or time cycled Pressure variable

35. Volume Ventilation Set Parameters: MODE: Full or Partial ventilator support Vt : 8 – 10 kg/IBW RR: 1o - 16 bpm FiO2: 21% - 100 % PFR: 40 - 60 lpm PEEP: 5 cmH2O FLOW PATTERN: Square wave SENSITIVITY: - 2 cmH2O or 1 L

36. MODES OF VOLUME VENTILATION

37. Different Modes On Volume Ventilation FULL VENTILATORY SUPPORT 1. Controlled Mandatory Ventilation (CMV) 2. Assist/Control PARTIAL VENTILATORY SUPPORT 1. Intermittent Mandatory Ventilation (IMV) 2. Synchronized Intermitent Mandatory Ventilation (SIMV)

38. Controlled Mandatory Ventilation CHARACTERISTIC DESCRIPTION Type of Breath Mechanical breath Triggering Mechanism time triggered/ machine triggered Cycling Mechanism time cycled Limit Volume limited Variable Pressure Variable Note: correction of PaCO2 level can be done through changing Tidal Volume and RR settings

39. Complications with Control Mode Potential for apnea and hypoxia due to: 1. disconnection from the ventilator 2. ventilator failure

40. Controlled Mandatory Ventilation

41. Assist/Control Ventilation CHARACTERISTIC DESCRIPTION Type of Breath Mechanical breath Triggering Mechanism Patient or time triggered Cycling Mechanism volume cycled/ time cycled Limit Volume limited Variable Pressure Variable Note: Correction of PaCO2 level can be done through changing Tidal Volume and RR settings Note: The generally accepted minimum RR for AC mode is 2 to 4 breaths per minute less than the patients assist rate or a minimum of 8-10 BPM

42. Assist/Control Ventilation

43. Complications Associated with AC Mode alveolar hyperventilation and respiratory alkalosis.

44. Intermittent Mandatory Ventilation CHARACTERISTIC DESCRIPTION Type of Breath Mechanical and spontaneous breaths Triggering Mechanism Patient or time triggered Cycling Mechanism volume cycled for mechanical breaths Limit Volume limited Variable Pressure Variable Note: Used as a weaning method. This mode uses a “ synchronization window ”

45. Synchronized Intermittent Mandatory Ventilation CHARACTERISTIC DESCRIPTION Type of Breath Mechanical and spontaneous breaths Triggering Mechanism Patient or time triggered Cycling Mechanism volume cycled for mechanical breaths Limit Volume limited Variable Pressure Variable

46. IMV AND SIMV MODE

47. OTHER SETTINGS OF VOLUME VENTILATION

48. Respiratory rate set at 12 – 16 bpm usual parameter that is manipulated to correct PaCO2 level affects the I:E ratio ↑ RR leads to ↓ I:E ratio or shorter E time ↓ RR leads to ↑ I:E ratio or longer E time

49. Tidal volume set parameter under volume ventilation, 8 – 10 ml/kg of PBW also manipulated to correct PaCO2 level affects I:E ratio ↑ Vt leads to ↑ I time or ↓ E time or ↓ I:E ratio ↓ Vt leads to decrease ↓ I time or ↑ E time or ↑ I:E ratio computed by obtaining Predicted Body Weight Male PBW in kg = 106 + [6 x (Height in inches – 60)] ÷ 2.2 Female PBW in kg = 105 + [5 x (Height in inches – 60)] ÷ 2.2

50. Peak flow rate initially set from 40 – 60 lpm determines how fast the set Vt is delivered affects I:E ratio ↑ PFR leads to ↓ I time or ↑ E time or ↑ I:E ratio ↓ PFR leads to ↑ I time or ↓ E time ↓ I:E ratio can cause dyssynchrony

51. I:E Ratio Changing I:E ratio using FLOW RATE Flow=Minute Volume x Sum of I:E ratio Changing I:E ratio using I time I time=Time for each breath x [I ratio/sum of I:E ratio] Using I time % to set I:E ratio I time %=I ratio/sum of I:E ratio

52. Peak flow pattern determines the manner of delivery of set Vt use to assess or monitor : 1. dyssynchrony 2. auto PEEP 3. changes in expiratory flow

53. Peak flow pattern has 4 available waveforms: 1. square wave – maximum flow is throughout inspiration 2. decelerating – maximum flow at start and diminishes as inspiration ends 3. sine wave – maximum flow at mid inspiration, resembles spontaneous breath 4. accelerating – maximum flow at end inspiration 5. decay – has some similarity with decelerating

54. Flow patterns

55. Most commonly used flow patterns Volume Pressure

56. Fio2 set from .21 to 1.0 or 21% to 100% the usual parameter manipulated to correct oxygenation causes oxygen toxicity

57. Sensitivity senses patient breathing effort has two types: Pressure sensitivity set from – 0.5 to – 5.0 cm H20 Flow sensitivity more sensitive to patient breathing effort compared to pressure set from 1 to 5 liters

58. Positive end expiratory pressure used in lung recruitment prevents collapse of alveoli prevents alveolar injury due to shearing effect of opening and closing of alveoli used to correct refractory hypoxemia caused by intrapulmonary shunting a PEEP of 5 cmH2O is used as a physiologic PEEP

59. Indications of peep 1. Intrapulmonary shunt and refractory hypoxemia PaO2 < 60mmHg with FiO2 of 50% and above PaO2/FiO2 (P/F) ratio < 200mmHg 2. Decrease FRC and lung compliance 3. auto PEEP not responsive to adjustments in ventilator settings 4. Pulmonary edema

60. Complications/hazards of peep 1. Barotrauma 2. Decrease venous return 3. Decrease cardiac output 4. Decrease urinary output

61. Complications/Hazards of PEEP Decrease O2 delivery

62. Positive Pressure Ventilation Pressure Ventilation

63. Pressure Ventilation CHARACTERISTICS: Pressure pre – set Pressure limited Time cycled, Flow cycled or Pressure cycled Volume variable use for invasive and non invasive ventilation

64. Pressure Ventilation Set Parameters: MODE: Full or Partial ventilator support PIP: 20cmH2O RR: 1o - 16 bpm FiO2: 21% - 100 % I time: 0.5-1 sec PEEP: 5 cmH2O I :E ratio: 1:3 SENSITIVITY: - 2 cmH2O or 1 L

65. MODES OF PRESSURE VENTILATION

66. Modes On Pressure Ventilation FULL VENTILATORY SUPPORT 1. PCV 2. Assist/Control 3. PC - IRV PARTIAL VENTILATORY SUPPORT 1. PSV 2. CPAP 3. BiPAP

67. Pressure Controlled Ventilation CHARACTERISTIC DESCRIPTION Type of Breath Mechanical breath Triggering Mechanism time triggered/ machine triggered Cycling Mechanism time cycled Limit Pressure limited Variable Volume Variable Note: usually indicated for patients with RDS

68. Assist/Control ventilation CHARACTERISTIC DESCRIPTION Type of Breath Mechanical breath Triggering Mechanism time triggered/ patient triggered Cycling Mechanism time cycled/pressure cycled Limit Pressure limited Variable Volume Variable

69. Pressure Control-Inverse Ratio Ventilation CHARACTERISTIC DESCRIPTION Type of Breath Mechanical breath Triggering Mechanism time triggered Cycling Mechanism time cycled Limit Pressure limited Variable Volume Variable Note: used to treat ARDS patients with refractory hypoxemia not responsive to conventional mechanical ventilation and PEEP

70. Pressure Support Ventilation CHARACTERISTIC DESCRIPTION Type of Breath Mechanical breath Triggering Mechanism patient triggered Cycling Mechanism Flow cycled Limit Pressure limited Variable Volume Variable Note: used as weaning method

71. Continuous Positive Airway Pressure Ventilation CHARACTERISTICS: Pressure limited use as a weaning method especially in infants used during non invasive ventilation (NIPPV) is a PEEP applied to the airway of a patient who is breathing spontaneously

72. Bilevel Positive Airway Pressure CHARACTERISTIC DESCRIPTION Type of Breath Mechanical breath Triggering Mechanism patient triggered/time triggered Cycling Mechanism Flow cycled/time cycled Limit Pressure limited Variable Volume Variable

73. Bilevel Positive Airway Pressure Bi-level positive airway pressure allows the clinician to apply independent positive airway pressures to both inspiration and expiration. Inspiratory (IPAP) and Expiratory (EPAP) are used to define when the positive airway pressure is present.

74. OTHER SETTINGS OF PRESSURE VENTILATION

75. Respiratory rate set at 10 – 16 bpm usual parameter that is manipulated to correct PaCO2 level affects the I:E ratio affects mean airway pressure ↑ RR leads to ↓ I:E ratio or shorter E time ↓ RR leads to ↑ I:E ratio or longer E time

76. Peak Inspiratory pressure (PIP) manipulated to correct PaCO2 level affects mean airway pressure ( mPaw )

77. Fio2 set from .21 to 1.0 or 21% to 100% the usual parameter manipulated to correct oxygenation can cause oxygen toxicity

78. Sensitivity senses patient breathing effort has two types: Pressure sensitivity set from – 0.5 to – 5.0 cm H20 Flow sensitivity more sensitive to patient breathing effort compared to pressure set from 1 to 5 liters

79. I time set from 1 sec to 1.5 seconds affects mean airway pressure

80. I:E Ratio ratio of inspiration to expiration normally set at 1:2 to 1: 4 affects mean airway pressure use inversely in conjunction with pressure ventilation (PCV-IRV) during: severe hypoxemia not responsive to conventional ventilation

81. Positive end expiratory pressure used in lung recruitment prevents collapse of alveoli prevents shearing effect used to correct refractory hypoxemia caused by intrapulmonary shunting a PEEP of 5 cmH2O is used as a physiologic PEEP affects mean airway pressure

82. Points to remember in pressure ventilation Increase in: pCO2 pO2 MAP FiO2 no change increase no change Rate decrease usually no change increase PIP decrease increase increase Inspiratory time usually no change increase increase PEEP usually no change increase increase

83. Terminologies Peak Inspiratory Pressure (PIP) or Peak Airway Pressure pressure used to deliver the tidal volume to the lung Plateau Pressure ( Pplat ) pressure that maintains lung inflation in the absence of airflow Mean airway Pressure ( mPaw ) average pressure within the airway during one complete respiratory cycle

84. Mean airway Pressure ( mPaw ) Normal value: < 30 cmH20 in adult Equation: mPaw = (f x I time) x ( PiP – PEEP) + PEEP 60 Where: mPaw – mean airway pressure (cmH20) f– respiratory in 1 minute I time – inspiratory time in 1 sec PIP – Peak inspiratory Pressure (cmH20) PEEP – Positive end expiratory Pressure