Mechanical ventilation

MECHANICAL VENTILATION

1. MECHANICAL VENTILATION BY: Mrs. Keerthi Samuel Assistant Professor Vijay MarieCON

2. “ Mechanical ventilation is the use of a ventilator to move room air or oxygen enriched air into and out of the lungs mechanically to maintain proper levels of oxygen and carbon dioxide in the blood.” DEFINITION

3. GOALS

4. To maintain gas exchange in case of acute and chronic respiratory failure. To maintain ventilator support after CPR. To reduce pulmonary vascular resistance. To excrete increased CO2 production. To give general anesthesia with muscle relaxants. PURPOSES

5. INDICATIONS

6. Respiratory failure: An inability of the heart and lungs to provide adequate tissue oxygenation or removal of carbon dioxide. Hypoxemic respiratory failure – lung failure Hypercapnic respiratory failure – pump failure Neuromuscular diseases : Myasthenia Gravis, Guillain-Barre Syndrome, and Poliomyelitis (failure of the normal respiratory neuromuscular system) Musculoskeletal abnormalities : Such as chest wall trauma . Infectious diseases : of the lung such as pneumonia, tuberculosis. INDICATIONS

7. Obstructive lung disease in the form of asthma, chronic bronchitis or emphysema. Conditions such as pulmonary edema, atelectasis, pulmonary fibrosis. Patients who has received general anesthesia as well as post cardiac arrest patients requires ventilatory support until they have recovered from the effects of the anesthesia or out from a Danger. INDICATIONS

8. PARAMETERS VENTILATOR INDICATED NORMAL RANGE A- Pulmonary function studies: Respiratory rate (breaths/min). Tidal volume (ml/kg body wt.) Vital capacity (ml/kg body wt.) Maximum Inspiratory Force (cm HO 2 ) ARTERIAL BLOOD GAS: PH PaO 2 (mmHg) PaCO 2 (mmHg) >35 <5 <15 <-20 < 7.25 < 60 > 50 15-20 5-7 65-75 75-100 7.35-7.45 75-100 35-45

9. TERM MEANING Independent variables The parameters that are set by clinician.” Dependent variables “ The parameters measured by the ventilators.” Fraction of inspired oxygen (FiO2): “The concentration of O2 in the inspired gas, usually between 21% and 100% O2. The lowest possible fraction of inspired oxygen (FiO2) necessary to meet oxygenation goals should be used. “ Tidal volume (TV): “The amount of air delivered to the patient per breath. It is expressed in milliliters.” A starting point for the VT setting is 8 to 10ml/kg of ideal weight. Respiratory rate/frequency (f): “ The number of breaths per minute. This can be from the ventilator, the patient, or both. “ The RR is set as near to physiological rates (14 to 20 breaths/min) as possible.

10. TERM MEANING Minute ventilation (V E): “ The product of V and respiratory frequency (VT * f). It is usually expressed in liters/minute.” Exhaled Tidal Volume:(E TV): “ It is the amount of gas that comes out of the patients lungs on exhalation.” This is the most accurate measure of the volume received by the patient If the ETV deviates from the set TV by 50ml or more, troubleshoot the system to identify the source of gas loss. Fraction of inspired oxygen (FiO2): “The concentration of O2 in the inspired gas, usually between 21% and 100% O2. The lowest possible fraction of inspired oxygen (FiO2) necessary to meet oxygenation goals should be used. “ Sigh : A deep breath , A breath that has a greater volume than the tidal volume. It provides hyperinflation and prevents atelectasis

11. TERM MEANING Inverse Inspiratory to Expiratory ratio: “I:E ratios such as 1:1,2:1 and 3:1 are called inverse I:E ratios” Inverse I:E ratio allows unstable alveoli time to fill and also prevents collapse by shortened expiratory phase. Sigh volume : Usual volume is 1.5 – 2 times tidal v o l u m e . Positive end-expiratory pressure (PEEP): “ “The amount of positive pressure that is maintained at end-expiration.” Typical settings for PEEP are 5 to 20 cm H2O PEEP increases oxygenation by preventing collapse of small airways It increases the functional residual capacity of the lungs A typical initial applied PEEP is 5 cmH2O. However, up to 20 cmH2O may be used in patients undergoing low tidal volume ventilation for acute respiratory distress syndrome (ARDS)

12. TERM MEANING Auto PEEP: “ Auto PEEP is the spontaneous development of PEEP caused by gas trapping in the lung resulting from insufficient expiratory time and incomplete exhalation.” Causes of auto PEEP formation include rapid RR, high VE demand, airflow obstruction and inverse I:E ratio ventilation. Auto PEEP = Total PEEP - Set PEEP Inspiratory to Expiratory ratio (I:E): “ The I:E ratio is usually set to mimic the pattern of spontaneous ventilation.” During spontaneous breathing, the normal I:E ratio is 1:2, indicating that for normal patients the exhalation time is about twice as long as inhalation time. If exhalation time is too short “breath stacking” occurs resulting in an increase in end- expiratory pressure also called auto-PEEP. Depending on the disease process, such as in ARDS, the I:E ratio can be changed to improve ventilation.

13. TERM MEANING Peak airway pressure (Paw): The pressure that is required to deliver the TV to the patient. It has a unit of centimeters of water (cm H2O).” Plateau pressure (Pplat): “ The pressure that is needed to distend the lung. This pressure can only be obtained by applying an end inspiratory pause. It also has a unit of cm H2O.” Mean airway pressure: “ The time-weighted average pressure during the respiratory cycle. It is expressed in cm H2O.” Peak inspiratory Pressure (PIP): In adults if the peak airway pressure is persistently above 45 cmH 2 O, the risk of barotrauma is increased and efforts should be made to try to reduce the peak airway pressure. “Increasing PIP is also sign of Blockage of airway and needed to suctioning or change Et /TT.” Sensitivity ( Trigger Sensitivity) : : “ The sensitivity function controls the amount of patient effort needed to initiate an inspiration.”

14. Inspiration : Inspiratory valve opens and expiratory valve is closed Inspiratory pause : inspiratory valve and expiratory valve closed Expiration : Inspiratory valve closed and expiratory valve open Expiratory Pause : Inspiratory valve and expiratory (PEEP) valve closed at the end of expiration PHASES OF VENTILATOR

15. Mode denotes interplay b/w patient and the ventilator Describes the style of breath support based on relationship between the various possible types of breath and inspiratory – phase variables MODES OF VENTILATOR

16. MODES OF VENTILATOR

17. CPAP is positive pressure applied throughout the respiratory cycle to the spontaneously breathing patient. A continuous level of elevated pressure is provided through the patient circuit to maintain adequate oxygenation, decrease the work of breathing. CPAP may be used invasively through an endotracheal tube or tracheostomy or noninvasively with a face mask or nasal prongs. CONTINOUS POSITIVE AIRWAY PRESSURE

18. provides pressure at end expiration, which prevents alveolar collapse and improves the functional residual capacity and oxygenation. CPAP allows the nurse to observe the ability of the patient to breath spontaneously while still on the ventilator. It may used as a Weaning Mode.

19. Similar to CPAP Non invasive mechanical ventilation. Indicated for sleep apnea patients with high pressure settings Used when CPAP fails Effective for CHF patients and often prescribed for patients with lung disorders or neuromuscular disorders. CPAP offers constant singular pressure difficult to exhale against. For patients with higher pressure strengths exhaling against an incoming air can feel difficult as BILEVEL POSITIVE AIRWAY PRESSURE

20. For patients with higher pressure strengths exhaling against an incoming air can feel difficult as if they are having to force their breathing out. Bipaps can also be set to include a breath timing feature that measures the amount of breaths per minute a person should be taking . If the time between the breaths exceeds the set limit , the machine can force the person to breath by temporarily increasing the air pressure. BiPAP has two pressure settings: a prescribed pressure for inhalation - Ipap and a lower pressure for exhalation Epap . This dual settings allow the patient to get more air into the lungs BILEVEL POSITIVE AIRWAY PRESSURE

21. In pressure controlled ventilation the breathing gas flows under constant pressure into the lungs during the selected inspiratory time. The flow is highest at the beginning of inspiration( i.e when the volume is lowest in the lungs). As the pressure is constant the flow is initially high and then decreases with increasing filling of the lungs. PRESSURE CONTROLLED VENTILATION

22. Pressure (or Pressure above PEEP) is the setting variable No mandatory breaths Applicable on Spontaneous breaths Patient effort determines size of breath and flowrate. It augments spontaneous V T, decreases spontaneous rates and WOB. Used in conjunction with spontaneous breaths in any mode of ventilation No back up ventilation in the event of apnea. Provides pressure support to overcome the increased work of breathing imposed by the disease process, the endotracheal tube, the inspiratory valves and other mechanical aspects of ventilatory support. Allows for titration of patient effort during weaning. PRESSURE SUPPORT VENTILATION

23. Inverse ratio ventilation (IRV) mode reverses this ratio so that inspiratory time is equal to, or longer than, expiratory time (1:1 to 4:1). Inverse I:E ratios are used in conjunction with pressure control to improve oxygenation by expanding stiff alveoli by using longer distending times, thereby providing more opportunity for gas exchange and preventing alveolar collapse. PC-INVERSE RATIO VENTILATION

24. II.VOLUME CONTROLLED VENTILATION

25. The ventilator provides the patient with a pre-set tidal volume at a pre-set rate. The patient may initiate a breath on his own, but the ventilator assists by delivering a specified tidal volume to the patient . Client can breathe at a higher rate than the preset number of breaths/minute ASSIST /CONTROLLED VENTILATION

26. The total respiratory rate is determined by the number of spontaneous inspiration initiated by the patient plus the number of breaths set on the ventilator. If the patient wishes to breathe faster, he or she can trigger the ventilator and receive a full-volume breath. Often used as initial mode of ventilation When the patient is too weak to perform the work of breathing (e.g. when emerging from anesthesia) ASSIST /CONTROLLED VENTILATION

27. The preset RR ensures that the patient receives adequate ventilation, regardless of spontaneous efforts. The patient can breath faster than the preset rate but not slower. ASSIST /CONTROLLED VENTILATION

28. Elongated tank, which encases the patient up to the neck. The neck is sealed with a rubber gasket, the patient's face are exposed to the room air. These exert negative pressure on the external chest decreasing the intra-thoracic pressure during inspiration, allows air to flow into the lungs, filling its volume. The cessation of the negative pressure causes the chest wall to fall and exhalation to occur. NEGATIVE PRESSURE VENTILATORS

29. A mode of mechanical ventilation in which the patient is allowed to breath independently except during certain prescribed intervals, when a ventilator delivers a breath either under positive pressure or in a measured volume. This mode is not use mostly in clinical practice due to many new tech. Modes. INTERMITTENT MANDATORY VENTILATION

30. PROS CONS Freedom for natural spontaneous breaths even on the machine Asynchrony Lesser chances of hyperventilation Random chances of breath stacking Increased work of breathing Random barotrauma and volutrauma INTERMITTENT MANDATORY VENTILATION

31. Ventilator delivers either patient triggered assisted breaths or time triggered mandatory breath in a synchronized fashion so as to avoid breath stacking If the patient breathes between mandatory breaths, the ventilator will allow the patient to breathe a normal breath by opening the demand (inspiratory) valve but not offering any inspiratory assistance. If patient does not make an inspiratory effort then ventilator will deliver a time triggered mandatory breath SYNCHRONIZED INTERMITTENT MANDATORY VENTILATOR

32. 3 types of breathing: Patient initiated assisted ventilation, Ventilator generated controlled ventilation, Unassisted spontaneous breath. SYNCHRONIZED INTERMITTENT MANDATORY VENTILATOR

33. The SIMV mode of ventilation delivers a set number of breaths of a set TV, and between these mandatory breaths the patient may initiate spontaneous breaths. If the patient initiates a breath near the time a mandatory breath is due, the delivery of the mandatory breath is synchronized with the patient’s spontaneous effort to prevent patient ventilator dys synchrony. In between the ventilator-delivered breaths , the patient is able to breath spontaneously at his own tidal volume and rate with no assistance from the ventilator. Ventilators breaths are synchronized with the patient spontaneous breath. SYNCHRONIZED INTERMITTENT MANDATORY VENTILATOR

34. Machine breaths are delivered at a set rate (volume or pressure limit) Patient is allowed to breath spontaneously from either a demand valve or a continuous flow of gases but not offering any inspiratory assistance. Patient’s capability determines Tidal volume of spontaneously breaths Some freedom to breath naturally even on mechanical ventilator INTERMITTENT MANDATORY VENTILATION

35. TYPES OF VENTILATORS

36. Non Invasive Ventilation: “ Ventilatory support that is given without establishing endo- tracheal intubation or tracheostomy is called Non invasive mechanical ventilation.” Invasive Ventilation: “Ventilatory support that is given through endotracheal intubation or tracheostomy is called as Invasive mechanical ventilation.” TYPES OF VENTILATORS

37. Negative pressure: Producing Neg. pressure intermittently in the pleural space/ around the thoracic cage. e.g.: Iron Lung Delivering air/gas with positive pressure to the airway.

38. The patient ’ s body was encased in an iron cylinder and negative pressure was generated The iron lung are still occasionally used today. These are simple to use and do not require intubations of the airway; consequently, they are especially adaptable for home use. It is used mainly in chronic respiratory failure associated with neuromuscular conditions such as poliomyelitis, muscular dystrophy and myasthenia gravis. The use of negative-pressure ventilators is restricted in clinical practice, however, because they limit positioning and movement and they lack adaptability to large or small body torsos (chests).

39. POSITIVE PRESSURE VENTILATION : inflate the lungs by exerting positive pressure on the airway forcing the alveoli to expand during inspiration. Expiration occurs passively. Positive-pressure ventilators require an artificial airway (Endotracheal or tracheostomy tube) in invasive ventilation and in NIV includes BiPAP Mask , O2 mask , Nasal mask/cannula , O2 high concentrated reservoir mask etc. Inspiration can be triggered either by the patient or the machine.

40. “ Ventilator Alarms defined as a Voice or sound to alert Nurse/Doctor and caused by any abnormal value of either in client or in Ventilator.” Check for bucking the vent These Alarms have 3 main Types as below : (i)Pressure alarms (ii)Volume alarms (iii)Apnea alarms VENTILATOR ALARMS

41. PRESSURE ALARMS They are triggered when there is increased airway resistance or decreased lung compliance. Low pressure alarms and high pressure alarms VOLUME ALARMS Volume alarms are valuable for ensuring adequate alveolar ventilation, particularly in the patient receiving a pressure mode of ventilation VENTILATOR ALARMS APNEA ALARMS This alarm is very important when the patient is on a spontaneous breathing mode such as PS or CPAP, and no mandatory breaths are set.

42. An alarm should never be silenced until the cause has been investigated and corrected. If the source of the alarm cannot be determined, disconnect the client from the ventilator and use a hand-held resuscitation bag for manual ventilation with 100% oxygen until the problem can be resolved TWO RULES….

43. COMPLICATIONS

44. Aspiration Decreased clearance of secretions Nosocomial or ventilator-acquired pneumonia (VAP) I.AIRWAY COMPLICATIONS

45. Hypoventilation with atelectasis with respiratory acidosis or hypoxemia. Hyperventilation with hypocapnia and respiratory alkalosis Barotrauma Closed pneumothorax, Tension pneumothorax, Subcutaneous emphysema. Alarm “ turned off ” Failure of alarms or ventilator Inadequate nebulization or humidification Overheated inspired air, resulting in hyperthermia MECHANICAL COMPLICATONS

46. Fluid overload with humidified air and sodium chloride (NaCl) retention Depressed cardiac function and hypotension Stress ulcers Paralytic ileus Gastric distension Starvation Dyssynchronous breathing pattern PHYSIOLOGICAL COMPLICATIONS

47. (A ) IN ENDOTRACHEAL TUBE : Tube kinked or plugged Tracheal stenosis or tracheomalacia Main stem intubation with contralateral (located on or affecting the opposite side of the lung) lung atelectasis Cuff failure Sinusitis Otitis media Laryngeal edema ARTIFICIAL AIRWAY COMPLICATIONS ( B) IN TRACHEOSTOMY TUBE : Acute haemorrhage at the site Air embolism Aspiration Tracheal stenosis Failure of the tracheostomy cuff Laryngeal nerve damage Obstruction of tracheostomy tube Pneumothorax Subcutaneous and mediastina emphysema Infection Accidental decannulation with loss of airway

48. SYSTEM WISE COMPLICATIONS SYSTEM COMPLICATIONS CARDIIOVASCULAR SYSTEM Increased intrathoracic pressure Reduced CO2 PULMONARY Barotrauma (trauma r/t pressure) Pneumothorax Subcutaneous emphysema Alveolar hypoventilation Cuff leak Ventilator settings Secretions Atelectasis Alveolar hyperventilation Due to hypoxemia, fear, pain, anxiety → alkalosis RX: sedate, analgesia, communication, correct hypoxemia Due to inappropriate ventilator settings high tidal volume High rate Pulmonary Infection

49. SYSTEM COMPLICATIONS NEUROLOGICAL Positive pressure ventilation → increased intrathoracic pressure interferes with venous drainage; increased ICP GI: Stress ulcers and GI bleeds; Rx with H 2 receptor blockers Gastric and bowel dilation Musculoskeletal: Muscle atrophy r/t immobilisation Mobilise ROM Psychologic: Stress Communication very important Sedate, explain, family visits, pain management Facilitate expression of needs

50. High Peak Pressures Low Plateau Pressures High Peak Pressures High Plateau Pressures Mucus Plug ARDS Bronchospasm Pulmonary Edema ET tube blockage Pneumothorax Biting ET tube migration to a single bronchus Effusion

51. Weaning is the process of withdrawing mechanical ventilator support and transferring the work of breathing from the ventilator to the patient which is done only when patient is free from the cause to be kept on mechanical ventilation. “Weaning success is defined as effective spontaneous breathing without any mechanical ventilation for 24 hours or more.” or “The process of going OFF from ventilator dependence to spontaneous breathing” WEANING

52. STAGES OF WEANING

53. CRITERIA FOR WEANING

54. It consists of removing the patient from the ventilator and having him / her breathe spontaneously on a T-piece connected to oxygen source. During T-piece weaning, periods of ventilator support are alternated with spontaneous breathing. The goal is to progressively increase the time spent of f the ventilator. 1.T-PIECE TRIAL

55. Observe for signs & Symptoms of…. Hypoxia, increasing fatigue, Tachy cardia- Ischemic ECG changes Restlessness RR > 35/min Use of accessory muscles for breathing Paradoxical chest movement 1.T-PIECE TRIAL

56. ET/TT removed only if following criterion met… Spontaneous ventilation is adequate Pharyngeal and laryngeal reflexes are active Pt maintain adequate airway and can swallow, move the jaw clench teeth , voluntary cough is effective to bring out secretion Before the tube is removed —a trail with nose/mouth breathing is done – Deflating cuff, using fenestrated tube etc 1.T-PIECE TRIAL

57. SIMV is the most common method of weaning. It consists of gradually decreasing the number of breaths delivered by the ventilator to allow the patient to increase number of spontaneous breaths. In pt’s who – satisfies all criteria for weaning but cannot have spontaneous breathing for long time. 2 .WEANING FROM VENTILATOR-SIMV

58. When placed on CPAP, the patient does all the work of breathing without the aid of a back up rate or tidal volume. No mandatory (ventilator-initiated) breaths are delivered in this mode i.e. all ventilation is spontaneously initiated by the patient. Weaning by gradual decrease in pressure value 2 .WEANING FROM VENTILATOR-CPAP

59. The patient must initiate all pressure support breaths. During weaning using the PSV mode the level of pressure support is gradually decreased based on the patient maintaining an adequate tidal volume (8 to 12 mL/kg) and a respirator y rate of less than 25 breaths/minute. PSV weaning is indicated for :- Difficult to wean patients Small spontaneous tidal volume. 2 .WEANING FROM VENTILATOR-PSV

60. Diaphoresis Dyspnea & Labored respirator y pattern Increased anxiety ,Restlessness, Decrease in level of consciousness Dysrhythmia , Increase or decrease in heart rate of > 20 beats /min. or heart rate > 110b/m , Sustained heart rate >20% higher or lower than baseline. Tidal volume ≤5 mL/kg, Sustained minute ventilation <200 mL/kg/minute SIGNS OF WEANING INTOLERANCE

61. Pt successfully weaned---- and has adequate respiratory function – weaned from O2 FIO2 is gradually reduced until SPO2 is in range of 80-100 mmHg while breathing in Room air If air SPO2 less than 70 supplementary O2 recommended 2 .WEANING FROM OXYGEN

62. Ineffective breathing pattern Potential for pulmonary infection Impaired water and fluid regulation Oral hygiene Potential altered nutritional status: less than body requirement related to NPO status Potential for complications related to immobility NURSING DIAGNOSIS

63. Knowledge deficit related to intubation and mechanical ventilation Elimination care Promoting coping ability Preventing trauma and infections Promoting rest and sleep Safety and security needs. NURSING DIAGNOSIS

64. LINK“ http:// www.nhlbi.nih.gov /health/healthtopics /topi cs/VENT/” LINK http://www.mmcwm.com/BiPAP LINK: “wwwappskc.lonestar.edu/programs/modes.p pt” WEBPAGE : WWW.WIKIPEDIA.COM & WWW. ENCYCLOPEDIA.COM , TOPIC OF MECHANICAL VENTILATOR & THEIR MODES REFERENCES