1. Selection of various parameters of non-invasive ventilator
1. Respiration mode selection
In the operation of non-invasive ventilator, the first thing to do is to select the patient’s breathing mode. There are three most commonly used modes in modern non-invasive ventilator:
(1) A/C (Assisted/Controlled Ventilation): When the patient breathes spontaneously, the mechanical ventilation starts with the breathing. Once the spontaneous breathing does not occur within a certain period of time, the mechanical ventilation automatically changes from assisted to controlled ventilation. It belongs to intermittent positive pressure ventilation.
(2) SIMV (Synchronized Intermittent Mandatory Ventilation): The ventilator receives a signal of negative pressure in the airway caused by spontaneous breathing at a certain interval, sends out airflow synchronously, and performs assisted ventilation intermittently.
(3) SPONT (spontaneous breathing): The work of the ventilator is controlled by the patient’s spontaneous breathing. In the above three basic modes, the non-invasive ventilator is also designed with respiratory functions for various diseases for selection when using. For example:
(a) PEEP (Positive End-Expiratory Pressure): On the basis of mechanical ventilation, a resistance is applied to the airway at the end of expiration to maintain the pressure in the airway at a certain level.
(b) CPAP (Continuous Positive Airway Pressure): Under the premise of spontaneous breathing, a certain degree of positive airway pressure is artificially applied throughout the breathing cycle. Prevents collapse of the airway.
(c) PSV (Pressure Support): Under the condition of spontaneous breathing, each inspiration receives a certain degree of pressure support.
(d) MMV (predetermined minute ventilation): if the minute ventilation of SPONT is lower than the limit, the insufficient volume will be supplied by the ventilator; the minute ventilation of SPONT is greater than the limit, The ventilator automatically stops supplying air.
(e) BIPAP (Bi-Level Positive Intra-Airway Pressure): The patient breathes spontaneously at different positive pressure levels. It can be regarded as PSV+CPAP+PEEP.
(f) APRV (Airway Pressure Release Ventilation): Under CPAP state, the low-pressure valve is opened to temporarily deflate and reduce airway pressure.
2, ventilation mode selection
After selecting the breathing mode, it is necessary to select or know the ventilation mode:
(1) Volume-controlled ventilation (VCV): set a tidal volume, which is adjusted by flow × inspiratory time.
(2) Pressure Controlled Ventilation (PCV): Set a pressure which is determined by the inspiratory plateau pressure.
3, trigger mode selection
(1) Pressure trigger: when the pressure in the pipeline reaches a certain limit , the breathing is switched.
(2) Flow trigger: when the flow rate in the pipeline changes to a certain value, the breathing is switched. Due to its high sensitivity and short lag time, it has been widely used.
(3) Time switch: controlled by time, when the set time is up, breathing will switch.
4. Alarm parameter selection
The settings of various parameters of the non-invasive ventilator are related to each other, so we need to Only by knowing the basic meaning and normal value range of various settings, can the alarm parameters be set accurately. Physiological indicators of adults using non-invasive ventilators are: tidal volume 5-7ml/kg; respiratory rate 12-20 times/min; airway pressure 30-35cmH2O; minute ventilation 6-10l/min.
In the use of non-invasive ventilators, the setting of the upper and lower alarm limits is also very important. If the alarm setting is too close to the actual value of the patient, the ventilator will cause frequent alarms; if the alarm setting range is too large, the alarm meaning will be lost. The settings of the alarm are different for different models, but generally should have:
(1) The upper and lower limits of the pipeline pressure alarm.
(2) The upper and lower limit of tidal volume alarm.
(3) Apnea interval time alarm.
(4) Minute ventilation volume upper and lower limit alarms.
(5) Upper and lower limit alarms of respiratory rate.
Second, Common problems and troubleshooting methods for non-invasive respirator
leak
1. Check whether the mask model is suitable for the patient’s face;
2. Check the tightness of the headband and whether the mask is properly fixed , Whether it is displaced;
3. Check whether the pipeline is disconnected.
The patient cannot tolerate NPPV
1. Is the mask suitable and how comfortable is the fixation?
2. The pressure setting is too low Or too high;
3. The temperature of the humidifier is too high, which makes the patient feel suffocated;
4. Timely and effective psychological care can eliminate the patient’s anxiety, anxiety and fear.
Asynchrony between human and machine
Patient factors:
1. Excessive breathing: slow down breathing and practice abdominal breathing;
2. Correction of hypoxemia: increase FiO2, increase IPAP or EPAP;
3. Excessive airway resistance: expectoration. Antispasmodic.
4. Mental stress
Ventilator factors:
1. Excessive air leakage;
2. Unreasonable parameter settings: CPAP, S/T;
3. Inappropriate trigger sensitivity: set a higher trigger sensitivity for fast breathing; set a lower trigger sensitivity for slow and weak breathing.
Expectation disorder
1. Encourage patients to actively expectorate and assist patients to expectorate sputum;
2. Turn over and pat back to promote Sputum drainage;
3. Atomization inhalation is beneficial to expectoration of sputum;
4. Vibrating machine for expectoration.
Sleep upper airway obstruction
1. Sleep in lateral position;
2. Apply chin rest;
3. Apply a higher EPAP.
Fear, Tension, Anxiety
1. Gain the patient’s trust;
2. Inform the patient about possible discomfort and How to deal with it;
3. Accompany when necessary.
flatulence
1. Ensure PaO2>?50mmHg with the lowest pressure;
2. Talk less;
3. Avoid mouth breathing;
4. Gastrointestinal decompression: gastrointestinal decompression can be used when IPAP≥20cmH2O!
Aspiration
1. Try not to use it for patients with possible aspiration;
2. Semi-recumbent position;
3. Avoid non-invasive ventilation immediately after a full meal.
Dry oropharynx
1. Reduce air leakage through the mouth and avoid mouth breathing;
2. Drink plenty of water;
3. Use a heated humidifier to adjust the appropriate temperature.
Mask crush
1. Mainly on the bridge of the nose;
2. The tightness of the fixed mask is moderate
3. Applying a decompression sticker to the prominence of the bone can reduce the pressure and also reduce air leakage.
The difference between invasive ventilator and non-invasive ventilator>>
