Mechanical ventilators- Applications and Usage
- 1. Health technology is defined by the World Health Organization as the "application of organized knowledge and skills in the form of devices, medicines, vaccines, procedures, and systems developed to solve a health problem and improve quality of lives“
- 2. MECHANICAL VENTILATORS Compiled by Dr. S.B.Sinha- Ex President Biomedical Engineering Society of India Health Technology Management Serie
- 4. MECHANICAL VENTILATORS- WHAT?? A medical ventilator is a Medical Device designed to mechanically force breathable air (mixture of Air and Oxygen) into and out of the lungs, to provide the mechanism of breathing for a patient who is physically unable to breathe, or breathing insufficiently. The ventilators are either Positive or Negative pressure. However Negative Pressure Ventilators are rarely used. Only Positive Pressure Ventilation is in use
- 7. COMPONEN TS OF A VENTILATO R 1, Power Supply 2. Air and Oxygen Hoses and Blenders. 3. Humidifier. 4. Patient Circuit 5. Inhalation and Exhalation Valves. 6. Flow Sensor. 7. Water Traps. 8. Control Circuits. 9. Switches and Fuses. 10. Other Electronic Hardware like Displays and Knobs.
- 8. COMMON VENTILATOR COMPONENTS Humidifier Patient Curcuit Air and Oxygen Hose Air/ Oxygen Mixer (Blender)
- 9. BASIC VENTILATOR PARAMETERS 1. Tidal Volume 2. Frequency. 3. PIP or Peak Inspiratory Pressure. 4. Positive End Expiratory Pressure or PEEP 5. Inspiratory Time.-Ti 6.Expiratory Time.-Te 7. I:E Ratio
- 10. VENTILATOR ALARMS A ventilator alarm is a safety mechanism on a mechanical ventilator that uses set parameters to provide alerts whenever there is a potential problem related to the patient-ventilator interaction. Common Ventilator Alarms are: 1. High Pressure Alarm.- Due to an obstruction in ventilator circuits or ET Tube 2. Low pressure Alarms by leaks 3. Low expired volume alarm- 4.High Frequency Alarm- 5. Apnea Alarm- when no expiration for preset time. 6. High and Low PEEP Alarm
- 11. NORMAL PARAMETERS SETTINGS OF VENTILATOR 1. Tidal Volume- 5- 15ml of body weight. 2. Respiratory Rate- 10-20 bpm for adults and 20-60 bpm for pediatric. 3. Oxygen Concentration- FiO2- 21-90% 4. I:E Ratio- 1:2 5. Flow Rate- 40- 100 lpm 6. Sensitivity Trigger-0.5- 1.5 cm H2O 7. Pressure Limit- 4-25 cm H2O 8. PEEP- 5-10 cm H2O
- 12. MODES OF MECHANICAL VENTILATOR 1. Controlled Mandatory Ventilation. CMV 2. Assist Control Mandatory Ventilation- ACMV 3. Synchronised Intermittent Mandatory Ventilation- SIMV 4. Positive End Expiratory Pressure.- PEEP 5. Continuous Positive Airway Pressure.- CPAP 6. Pressure Support Ventilation- PSV
- 14. VENTILATOR PHASE VARIABLES 1. Trigger- By Ventilator- time; By Patient- pressure or flow. 2. Limit- Flow Limited or Pressure Limited
- 15. MODES IN VENTILATIO N 2. Describes the breath support based on relationship between various possible types of breath and inspiratory-expiratory phase variables 1. Modes are process by which the mechanical ventilator determines, either partially or fully, when the mechanical breaths are to be provided to the patient, thus determining the breathing pattern of the patient during mechanical ventilation.
- 16. BREATH TYPES
- 17. BREATH TYPES 1. Controlled Breath- When the patient is not breathing at all. All the ventilation is delivered by the Ventilator. No work of breathing by patient. 2. Assisted Breath- When patient tries to breath and Ventilator takes over the work of breathing. 3. Supported Breath- When patient is able to do some or most of the work of breathing. Ventilator supports to finish the breathing. 4. Spontaneous Breath- When patient breathes on its own.
- 19. CMV- CONTROLL ED MANDATOR Y VENTILATIO N 1. Patient can’t breath on its own. 2. Patient can’t change the respiratory rates. 3. Suitable only when patient is not making any breathing efforts and is under sedation or because of a disease.
- 20. ASSIST CONTROL MANDATORY VENTILATION In Asst Control Mode the patient tries to breathe but the breathing is still delivered by the patient. Patient is not allowed to breath on its own.
- 21. SIMV-SYNCHRONISED INTERMITTENT MANDATORY VENTILATION This mode is used when the patient has started breathing. Thus patient breathing is synchronized with the ventilation by the ventilator. The patient will be allowed to breathe and when it is unable to breathe the ventilator will provide the breathing. The patient's bpm is set as per requirement and this breathing is guaranteed to the patient but this consists of partially the patients breathing and partially by the Ventilator.
- 22. SIMV-CONTD. The Ventilator delivers either patient triggered assisted breath or time triggered mandatory breaths in a synchronised manner so as to avoid ventilator fighting with the patient. If the patient breathes between mandatory breaths, the ventilator will allow patient to breath by opening the demand (inspiratory) valve but not offering any inspiratory assistance.
- 23. PCV- PRESSURE CONTROLLED VENTILATION In his Mode the inspiration Cycle maintains a pressure limit set by the machine. The Volume may not be guaranteed but pressure will never exceed the Maximum pressure set in the Ventilator. In Pressure Controlled Mode 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.
- 24. PRESSURE SUPPORT VENTILATION The patient breathes spontaneously while the ventilator applies a pre-determined amount of positive pressure to the airways upon inspiration. Pressure is the setting Variable. No mandatory breath. Applicable on spontaneous breath in any mode. Patient effort determine the size of breath and Flow rate. No back up ventilation in event of Apnes.
- 25. CPAP- CONTINUO US POSITIVE AIRWAY PRESSURE CPAP- Is the continuous positive airway pressure applied to spontaneously breathing patients. A continuous elevated pressure is provided to the patient circuit to maintain adequate oxygenation and decrease work of breathing. CPAP can be used invasively through ET Tube or non invasively through a Mask. It may be used during weaning.
- 26. BIPAP- BILEVEL POSITIVE AIRWAY PRESSURE BiPAP is a noninvasive form of mechanical ventilation provided by means of a nasal mask or nasal prongs, or a full-face mask. The system allows the clinician to select two levels of positive-pressure support: An inspiratory pressure support level (referred to as IPAP) End expiratory pressure called EPAP (PEEP/CPAP level). •There are Ventilators which perform both BIPAP and CPAP functions and are known as BIPAP Machines
- 28. HIGH FREQUENCY VENTILATORS - In some advanced ventilators this mode is present. High-frequency ventilators use small tidal volumes (1 to 3 mL/kg) at frequencies greater than 100 breaths/minute. The high-frequency ventilator accomplishes oxygenation by the diffusion of oxygen and carbon dioxide from high to low gradients of concentration
- 29. INSTALLATION OF A VENTILATOR 1. Connect the Power Supply cable. 2. Connect the Air and Oxygen Sources. 3. Assemble the Humidifier and patient circuit. 4. Connect a test lung. 5. Switch ON the Ventilator. 6. Do the minimal testing. 7. Connect to the patient
- 30. QUICK TESTING BEFORE USE 1. Attach the Calibrated Test Lung of 1 litre with Max Volume Set at 650 ml 2. Switch ON and Quick Check Test Parameter set as below: a) Mode- Asst Control/CMV b) TV- 500 ml c) RR- 15 bpm d) Ti= 1.3 Sec e) PEEP= 5 cm H2O f) FiO2= 60% g) Waveform- Square 3) i) Check the PIP display. It should be 27 cm H2O+/-2 ii) Check the FiO2 display- It should be 60%+/-3%
- 31. TROUBLESHO OTING COMMON PROBLEMS. 1. Power Supply- Check the cable and wall outlet for AC Power supply if the Ventilator is not switching ON. 2. If there is problem in Oxygen check the Oxygen Supply. 3. If there is alarm check for occlusions, leaks, and filters.
- 32. PREVENTIVE MAINTENAN CE Cleaning- a) Remove any dust, dirt, water, waste matter, tape and paper daily. b) Clean inside and outside with damp clothes and dry off weekly c) Remove dirt from wheels and other moving parts on a weekly basis. Audiovisual Checks: DAILY a. If any leak is audible, check with soapy solution. b. Check all seals, connectors, adapters and parts are tight. c. Check all moving parts move freely, all holes are unblocked. WEEKLY a) Check connections for leaks with soap solution and dry off. b) Check all fittings and valves for proper assembly. c) Replace and deteriorated tubing and hoses. d) If seal, plug, sockets are damaged replace them.
- 33. CALIBRATION FOR PRESSURE 1. Construct a manometer to measure pressure in centimeters of H2O. a. Use a large non-inflatable jug as the reservoir. Most water jugs will work. b. Fill the jug half-full with water. c. Insert the patient output from the ventilator into the plastic jug. Also insert one end of the clear plastic tubing into the plastic jug. The end of the plastic tube should be near the bottom. d. Seal the tubes with latex gloves and tape. Insure that no air can escape from the jug opening. 2. Set the pressure limit on the ventilator. Record this pressure in Table 1 below. 3. Hold the clear plastic tubing straight up. Use a tape measure to measure the peak height of the water in cm H2O. Measure from the water level in the jug to the maximum height reached in the clear plastic tubing. Record this measurement . The height of the water is the pressure. 4. Repeat Steps 2-3 for four settings of pressure. 5. To determine if the ventilator is accurate enough, show your table to the physician that uses the ventilator. The set and measured reading should match.
- 34. CALIBRATIO N FOR VOLUME 4. Turn ON the Ventilator. Allow the Ventilator to deliver 01 breath. The top of graduated cylinder should fill up with Air as shown in figure below. Now stop the Ventilator. Read the air level that has displaced the water level. This is the tidal volume. Repeat the process and take four readings and tabulate in table. The Set and measured value should match. 3. Connect a tube to the output of the ventilator (normally the tube leading to the patient would be connected here). The other end of the tube is placed within the measuring cylinder. Lift the measuring cylinder up, close to the water level as fig below. Note down the exact level of water in the measuring cylinder (if it is not completely filled with water). 2. Then, turn the measuring cylinder up by 90 degrees so it sits up-side-down in the basin. 1. Ensure that the patient output tube is at least 80 cm long. Set the tidal Volume to 500 ml which is the average tidal volume for adults. Fill a plastic tub with water. The tub should be big enough to accommodate a 1 litre graduated cylinder.
- 35. THANK YOU- Q/A(IMAGE-EE TIMES)