Mechanical ventilation ppt
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Slide 1 NURSING MANAGEMENT OF MECHANICALLY VENTILATED PATIENTS Presented By Bibini Baby 2nd year MSc. Nsg Govt. College of Nsg Kottayam 1 Spontaneous respiration vs. Mechanical ventilation Natural Breathing Negative inspiratory force Air pulled into lungs Mechanical Ventilation Positive inspiratory pressure Air pushed into lungs 2 Mechanical ventilation Negative pressure Positive pressure Invasive Noninvasive 3 Negative-Pressure Ventilators Early negative-pressure ventilators were known as “iron lungs.” The patient’s body was encased in an iron cylinder and negative pressure was generated The iron lung are still occasionally used today. 4 5 Intermittent short-term negative-pressure ventilation is sometimes used in patients with chronic diseases. 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) . Our focus will be on the positive-pressure ventilators. 6 POSITIVE PRESSURE VENTILATION (INVASIVE) 7 Initiation of Mechanical Ventilation Indications Indications for Ventilatory Support Acute Respiratory Failure Prophylactic Ventilatory Support Hyperventilation Therapy 8 8 Initiation of Mechanical Ventilation Indications Acute Respiratory Failure (ARF) Hypoxic lung failure (Type I) Ventilation/perfusion mismatch Diffusion defect Right-to-left shunt Alveolar hypoventilation Decreased inspired oxygen Acute life-threatening or vital organ-threatening tissue hypoxia 9 9 Initiation of Mechanical Ventilation Indications Acute Respiratory Failure (ARF) Acute Hypercapnic Respiratory Failure (Type II) CNS Disorders Reduced Drive To Breathe: depressant drugs, brain or brainstem lesions (stroke, trauma, tumors), hypothyroidism Increased Drive to Breathe: increased metabolic rate (CO2 production), metabolic acidosis, anxiety associated with dyspnea 10 10 Initiation of Mechanical Ventilation Indications Acute Respiratory Failure (ARF) Acute Hypercapnic Respiratory Failure (Type II) Neuromuscular Disorders Paralytic Disorders: Myasthenia Gravis, Guillain-Barre´11, poliomyelitis, etc. Paralytic Drugs: Curare, nerve gas, succinylcholine, insecticides Drugs that affect neuromuscular transmission; calcium channel blockers, long-term adenocorticosteroids, etc. Impaired Muscle Function: electrolyte imbalance, malnutrition, chronic pulmonary disease, etc. 11 11 Curare-plant poison, nerve gas-sarine of OP poisoning Initiation of Mechanical Ventilation Indications Acute Respiratory Failure (ARF) Acute Hypercapnic Respiratory Failure Increased Work of Breathing Pleural Occupying Lesions: pleural effusions, hemothorax, empyema, pneumothorax Chest Wall Deformities: flail chest, kyphoscoliosis, obesity Increased Airway Resistance: secretions, mucosal edema, bronchoconstriction, foreign body Lung Tissue Involvement: interstitial pulmonary fibrotic diseases 12 12 Initiation of Mechanical Ventilation Indications Acute Respiratory Failure (ARF) Acute Hypercapnic Respiratory Failure Increased Work of Breathing (cont.) Lung Tissue Involvement: interstitial pulmonary fibrotic diseases, aspiration, ARDS, cardiogenic PE, drug induced PE Pulmonary Vascular Problems: pulmonary thromboembolism, pulmonary vascular damage Dynamic Hyperinflation (air trapping) Postoperative Pulmonary Complications 13 13 Initiation of Mechanical Ventilation Prophylactic Ventilatory Support Clinical conditions in which there is a high risk of future respiratory failure Examples: Brain injury, heart muscle injury, major surgery, prolonged shock, smoke injury Ventilatory support is instituted to: Decrease the WOB Minimize O2 consumption and hypoxemia Reduce cardiopulmonary stress Control airway with sedation 14 14 Initiation of Mechanical Ventilation Hyperventilation Therapy Ventilatory support is instituted to control and manipulate PaCO2 to lower than normal levels Acute head injury 15 15 Criteria for institution of ventilatory support: Normal range Ventilation indicated Parameters 10-20 5-7 65-75 75-100 > 35 < 5 < 15 50 B- Arterial blood Gases PH PaO2 (mmHg) PaCO2 (mmHg) 17 Initiation of Mechanical Ventilation Contraindications Untreated pneumothorax Relative Contraindications Patient’s informed consent Medical futility Reduction or termination of patient pain and suffering 18 18 Essential components in mechanical ventilation Patient Artificial airway Ventilator circuit Mechanical ventilator A/c or D/c power source O2 cylinder or central oxygen supply 19 Artificial airways Tracheal intubation Nasal Oral Supraglottic airway Cricothyrotomy Tracheostomy 20 Cricothyrotomy-btwn thyroid and cricoid cartilage, tracheostomy- btwn 2 and 4 tracheal ring 20 Laryngeal airway 21 Intubation Procedure Check and Assemble Equipment: Oxygen flowmeter and O2 tubing Suction apparatus and tubing Suction catheter Ambu bag and mask Laryngoscope with assorted blades 3 sizes of ET tubes Stillet Stethoscope Tape Syringe Sterile gloves 22 Intubation Procedure Position your patient into the sniffing position 23 Intubation Procedure Preoxygenate with 100% oxygen to provide apneic or distressed patient with reserve while attempting to intubate. Do not allow more than 30 seconds to any intubation attempt. If intubation is unsuccessful, ventilate with 100% oxygen for 3-5 minutes before a reattempt. 24 Intubation Procedure Insert Laryngoscope 25 Laryngoscope is always held in the left hand and is used to displace the tongue to the left so that the epiglottis may be seen. Intubation Procedure After displacing the epiglottis insert the ETT. The depth of the tube for a male patient on average is 21-23 cm at teeth The depth of the tube on average for a female patient is 19-21 at teeth. 26 An easy trick to use is tube size X 3 – works almost all the time. Intubation Procedure Confirm tube position: By auscultation of the chest Bilateral chest rise Tube location at teeth CO2 detector – (esophageal detection device or by capnography) 27 You must rule out an esophageal intubation with capnography or by BS. Always listen over the epigastrium after listening to the chest. These are bedside procedures that must be done immediately after intubation prior to an XRAY. Intubation Procedure Stabilize the ETT 28 Can be done with tape or a commercially available ETT stabilizer. Always tape above the ETT and never to the chin. Ventilator circuit Breathing System Plain Breathing System with Single Water Trap Breathing System with Double Water Trap. Breathing Filters HME Filter Flexible Catheter Mount 29 30 Ventilator circuit Breathing system plain 31 Ventilator Breathing System (1.6m) Ventilator Breathing System (1.6m) with Y piece, monitoring ports, water trap and manual fill humidification chamber 31 32 Ventilator Breathing System (1.6m) Ventilator Breathing System (1.6m) with Y piece, monitoring ports, 2 water traps and manual fill humidification chamber 32 heat & moisture exchanger HME filter 33 34 MECHANICAL VENTILATOR A mechanical ventilator is a machine that generates a controlled flow of gas into a patient’s airways. Oxygen and air are received from cylinders or wall outlets, the gas is pressure reduced and blended according to the prescribed inspired oxygen tension (FiO2), accumulated in a receptacle within the machine, and delivered to the patient using one of many available modes of ventilation. 35 Types of Mechanical ventilators Transport ventilators Intensive-care ventilators Neonatal ventilators Positive airway pressure ventilators for NIV 36 Classification of positive-pressure ventilators Ventilators are classified according to how the inspiratory phase ends. The factor which terminates the inspiratory cycle reflects the machine type. They are classified as: 1- Pressure cycled ventilator 2- Volume cycled ventilator 3- Time cycled ventilator 37 1- Volume-cycled ventilator Inspiration is terminated after a preset tidal volume has been delivered by the ventilator. The ventilator delivers a preset tidal volume (VT), and inspiration stops when the preset tidal volume is achieved. 38 2- Pressure-cycled ventilator In which inspiration is terminated when a specific airway pressure has been reached. The ventilator delivers a preset pressure; once this pressure is achieved, end inspiration occurs. 39 3- Time-cycled ventilator In which inspiration is terminated when a preset inspiratory time, has elapsed. Time cycled machines are not used in adult critical care settings. They are used in pediatric intensive care areas. 40 Mechanical Ventilators Different Types of Ventilators Available: Will depend on your place of employment Ventilators in use in MCH Servo S by Maquet Savina by Drager 41 42 43 MODES OF VENTILATION 44 Ventilator mode The way the machine ventilates the patient How much the patient will participate in his own ventilatory pattern. Each mode is different in determining how much work of breathing the patient has to do. 45 A- Volume Modes 1. CMV or CV 2. AMV or AV 3. IMV 4. SIMV 46 B- Pressure Modes 1- Pressure-controlled ventilation (PCV) 2- Pressure-support ventilation (PSV) 3- Continuous positive airway pressure (CPAP) 4- Positive end expiratory pressure (PEEP) 5- Noninvasive bilevel positive airway pressure ventilation (BiPAP) 47 Control Mode Delivers pre-set volumes at a pre-set rate and a pre-set flow rate. The patient CANNOT generate spontaneous breaths, volumes, or flow rates in this mode. 48 Control Mode 49 Assist/Control Mode Delivers pre-set volumes at a pre-set rate and a pre-set flow rate. The patient CANNOT generate spontaneous volumes, or flow rates in this mode. Each patient generated respiratory effort over and above the set rate are delivered at the set volume and flow rate. 50 Assist Control Volume or Pressure control mode Parameters to set: Volume or pressure Rate I – time FiO2 51 Assist Control Machine breaths: Delivers the set volume or pressure Patient’s spontaneous breath: Ventilator delivers full set volume or pressure & I-time Mode of ventilation provides the most support 52 Negative deflection, triggering assisted breath Assist Control 53 Notice how the patient’s breath reflects the ventilator breath. Not for conscious patients! Delivers a pre-set number of breaths at a set volume and flow rate. Allows the patient to generate spontaneous breaths, volumes, and flow rates between the set breaths. Detects a patient’s spontaneous breath attempt and doesn’t initiate a ventilatory breath – prevents breath stacking SYCHRONIZED INTERMITTENT MANDATORY VENTILATION (SIMV): 54 SIMV Synchronized intermittent mandatory ventilation Machine breaths: Delivers the set volume or pressure Patient’s spontaneous breath: Set pressure support delivered Mode of ventilation provides moderate amount of support Works well as weaning mode 55 SIMV cont. 56 Machine Breaths Spontaneous Breaths IMV 57 Ingento EP & Drazen J: Mechanical Ventilators, in Hall JB, Scmidt GA, & Wood LDH(eds.): Principles of Critical Care 57 Ref: Ingento EP and Drazen J: Mechanical ventilators, in Hall JB, Scmidt GA, and Wood LDH(eds.): Principles of Critical Care. New York, McGraw-Hill, Inc., 1992, p.145. “Positive pressure, volume-cycled breaths are delivered at a preset rate similar to control mode ventilation, except that between breaths, the inspiratory valve to the patient is open, allowing for spontaneous breathing.” 58 Volume Modes PRESSURE REGULATED VOLUME CONTROL (PRVC): This is a volume targeted, pressure limited mode. (available in SIMV or AC) Each breath is delivered at a set volume with a variable flow rate and an absolute pressure limit. The vent delivers this pre-set volume at the LOWEST required peak pressure and adjust with each breath. 59 PRVC (Pressure regulated volume control) A control mode, which delivers a set tidal volume with each breath at the lowest possible peak pressure. Delivers the breath with a decelerating flow pattern that is thought to be less injurious to the lung…… “the guided hand”. 60 60 This mode combines the benefit of a volume mode (guaranteed minute ventilation) with the benefits of a pressure mode (decelerating flow pattern and a lower PIP for the same tidal volume as compared to volume control). PRCV: Advantages Decelerating inspiratory flow pattern Pressure automatically adjusted for changes in compliance and resistance within a set range Tidal volume guaranteed Limits volutrauma Prevents hypoventilation 61 PRVC: Disadvantages Pressure delivered is dependent on tidal volume achieved on last breath Intermittent patient effort variable tidal volumes Pressure Flow Volume Set tidal volume © Charles Gomersall 2003 62 Pressure Flow Volume Set tidal volume PRVC: Disadvantages Pressure delivered is dependent on tidal volume achieved on last breath Intermittent patient effort variable tidal volumes © Charles Gomersall 2003 63 PRVC 64 POSITIVE END EXPIRATORY PRESSURE (PEEP): This is NOT a specific mode, but is rather an adjunct to any of the vent modes. PEEP is the amount of pressure remaining in the lung at the END of the expiratory phase. Utilized to keep otherwise collapsing lung units open while hopefully also improving oxygenation. Usually, 5-10 cmH2O 65 66 Pplat Measured by occluding the ventilator 3-5 sec at the end of inspiration Should not exceed 30 cmH2O 67 Peak Pressure (Ppeak) Ppeak = Pplat + Pres Where Pres reflects the resistive element of the respiratory system (ET tube and airway) 68 Ppeak Pressure measured at the end of inspiration Should not exceed 50cmH2O? 69 Auto-PEEP or Intrinsic PEEP Normally, at end expiration, the lung volume is equal to the FRC When PEEPi occurs, the lung volume at end expiration is greater than the FRC 70 Auto-PEEP or Intrinsic PEEP Why does hyperinflation occur? Airflow limitation because of dynamic collapse No time to expire all the lung volume (high RR or Vt) Decreased Expiratory muscle activity Lesions that increase expiratory resistance 71 Auto-PEEP or Intrinsic PEEP Adverse effects: Predisposes to barotrauma Predisposes hemodynamic compromises Diminishes the efficiency of the force generated by respiratory muscles Augments the work of breathing Augments the effort to trigger the ventilator 72 This is a mode and simply means that a pre-set pressure is present in the circuit and lungs throughout both the inspiratory and expiratory phases of the breath. CPAP serves to keep alveoli from collapsing, resulting in better oxygenation and less WOB. The CPAP mode is very commonly used as a mode to evaluate the patients readiness for extubation. 73 Continuous Positive Airway Pressure (CPAP): 73 Please note that the patient has to be spontaneously breathing to use this mode! Often used in conjunction with weaning the patient from the ventilator. Combination “Dual Control” Modes Combination or “dual control” modes combine features of pressure and volume targeting to accomplish ventilatory objectives which might remain unmet by either used independently. Combination modes are pressure targeted Partial support is generally provided by pressure support Full support is provided by Pressure Control 74 74 Combination “Dual Control” Modes Volume Assured Pressure Support (Pressure Augmentation) Volume Support (Variable Pressure Support) Pressure Regulated Volume Control (Variable Pressure Control, or Autoflow) Airway Pressure Release (Bi-Level, Bi-PAP) 75 75 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. 76 As expiratory time is decreased, one must monitor for the development of hyperinflation or auto-PEEP. Regional alveolar overdistension and barotrauma may occur owing to excessive total PEEP. When the PCV mode is used, the mean airway and intrathoracic pressures rise, potentially resulting in a decrease in cardiac output and oxygen delivery. Therefore, the patient’s hemodynamic status must be monitored closely. Used to limit plateau pressures that can cause barotrauma & Severe ARDS 77 HIGH FREQUENCY OSCILLATORY VENTILATION HIFI - Theory Resonant frequency phenomena: Lungs have a natural resonant frequency Outside force used to overcome airway resistance Use of high velocity inspiratory gas flow: reduction of effective dead space Increased bulk flow: secondary to active expiration 79 HIFI - Advantages Advantages: Decreased barotrauma / volutrauma: reduced swings in pressure and volume Improve V/Q matching: secondary to different flow delivery characteristics Disadvantages: Greater potential of air trapping Hemodynamic compromise Physical airway damage: necrotizing tracheobronchitis Difficult to suction Often require paralysis 80 HIFI – Clinical Application Adjustable Parameters Mean Airway Pressure: usually set 2-4 higher than MAP on conventional ventilator Amplitude: monitor chest rise Hertz: number of cycles per second FiO2 I-time: usually set at 33% 81 Comparison of HFOV & Conventional Ventilation Differences CMV HFOV Rates 0 - 150 180 - 900 Tidal Volume 4 - 20 ml/kg 0.1 - 3 ml/kg Alveolar Press 0 - > 50 cmH2O 0.1 - 5 cmH2O End Exp Volume Low Normalized Gas Flow Low High 82 Video on HFOV http://youtube.com/watch?v=jLroOPoPlig 83 83 9 minute video – I just want to show how the oscillator sounds and what it looks like. INITIAL SETTINGS 84 Select your mode of ventilation Set sensitivity at Flow trigger mode Set Tidal Volume Set Rate Set Inspiratory Flow (if necessary) Set PEEP Set Pressure Limit Inspiratory time Fraction of inspired oxygen 84 Flow Trigger allows the patient to pull a spontaneous breath from the vent whenever he wants. Tidal Volume is the amount of air the patient is given with each breath (10-12 ml/kg IBW) Rate is normally set at 10-12 bpm (adults) and then changed via ABG Flow – most new vents set the flow to deliver a set I:E ratio. Flow of 40-80 L/min to achieve an I:E of approximately 1:2. PEEP – 3-5 cmH20 is physiologic peep Pressure Limit – set at 10 – 20 cmH20 above pt’s own PIP Humidification – heated to 35-37°C to provide humidification due to bypassed upper airways Trigger There are two ways to initiate a ventilator-delivered breath: pressure triggering or flow-by triggering When pressure triggering is used, a ventilator-delivered breath is initiated if the demand valve senses a negative airway pressure deflection (generated by the patient trying to initiate a breath) greater than the trigger sensitivity. When flow-by triggering is used, a continuous flow of gas through the ventilator circuit is monitored. A ventilator-delivered breath is initiated when the return flow is less than the delivered flow, a consequence of the patient's effort to initiate a breath 85 Post Initial Settings 86 Obtain an ABG (arterial blood gas) about 30 minutes after you set your patient up on the ventilator. An ABG will give you information about any changes that may need to be made to keep the patient’s oxygenation and ventilation status within a physiological range. 86 ABG 87 Goal: Keep patient’s acid/base balance within normal range: pH 7.35 – 7.45 PCO2 35-45 mmHg PO2 80-100 mmHg 87 Any variance in these values will require a change made to this patient’s ventilator. Initiation of Mechanical Ventilation Initial Ventilator Settings Tidal Volume Spontaneous VT for an adult is 5 – 7 ml/kg of IBW Determining VT for Ventilated Patients A range of 6 – 12 ml/kg IBW is used for adults 10 – 12 ml/kg IBW (normal lung function) 8 – 10 ml/kg IBW (obstructive lung disease) 6 – 8 ml/kg IBW (ARDS) – can be as low as 4 ml/kg A range of 5 – 10 ml/kg IBW is used for infants and children 88 88 Initiation of Mechanical Ventilation Initial Ventilator Settings Respiratory Rate Normal respiratory rate is 12-18 breaths/min. A range of 8 – 12 breaths per minute (BPM) Rates should be adjusted to try and minimize auto-PEEP 89 89 Initiation of Mechanical Ventilation Initial Ventilator Settings Minute Ventilation Respiratory rate is chosen in conjunction with tidal volume to provide an acceptable minute ventilation = VT x f Normal minute ventilation is 5-10 L/min Estimated by using 100 mL/kg IBW ABG needed to assess effectiveness of initial settings If PaCO2 >45 ( minute ventilation via f or VT) If PaCO2 5 cm H2O) Hypotension Elevated ICP Uncontrolled pneumothorax 97 97 Initiation of Mechanical Ventilation Initial Ventilator Settings FiO2 Initially 100% Severe hypoxemia Abnormal cardiopulmonary functions Post-resuscitation Smoke inhalation ARDS After stabilization, attempt to keep FiO2