Main causes and treatment measures of airway high pressure alarm during ventilator-assisted ventilation
1. Ventilation alarm:
⑴ The patient triggered the low ventilation alarm: ⑴ The patient's spontaneous breathing ability was poor. When using IMV, SIMV, PSV, CPAP and other methods, the patient's breathing frequency is slow, the rhythm is irregular, and the tidal volume is small. , leading to insufficient breathing, reducing ventilation per minute and triggering an alarm. At this time, the number of controlled ventilation or pressure or tidal volume should be appropriately increased on the basis of the original ventilation mode, and some patients with weak spontaneous breathing should be changed to controlled ventilation. ② Patients with airway obstruction, especially during constant pressure ventilation. Obstruction should be relieved in time, and secretions should be sucked out: if it is blocked by sticky sputum, it should be fully humidified, and sputum should be sucked regularly to ensure smooth respiratory tract; If it is caused by tracheal spasm, it can be changed from constant pressure to constant volume, and active drug treatment can be given to relieve tracheal spasm, or the ventilation pressure can be appropriately increased on the basis of the original volume to ensure adequate ventilation.
2 ventilator or catheter facilities trigger low ventilation alarm:
① Less ventilation: If the TV is small or under pressure or the frequency is slow; In a ventilator with constant air volume within a certain time limit, small air volume and short breathing time will lead to low ventilation volume per minute (mv) and trigger an alarm. Ventilation conditions should be rechecked and TV, pressure or frequency, flow rate or inspiratory time should be increased.
② The low limit alarm equipment is too high, and the ventilation meter is inaccurate: at this time, the patient is well ventilated and there is no hypoventilation. The alarm limit should be reset or the MV should be recalibrated with a hygrometer.
③ The dead space is too large: under the condition of constant mechanical ventilation, additional ventilator pipes are added, or there is too little liquid in the humidifying bottle.
To minimize the extra dead space, remove the long tracheal catheter outside the nasal cavity (the baby should keep it 2~3cm), use the catheter fixed by the ventilator itself, remove the extension tube, and check the liquid level of the humidification bottle frequently.
(4) Air leakage: including air leakage caused by too thin tracheal tube or cannula, looseness between connecting tubes of ventilator, broken connecting tubes, lax sealing of humidification bottle, and air leakage inside ventilator.
Pipes should be closely connected, and they should be replaced when they are broken or not tight; If the cannula or cannula is slightly thin and leaks from the cannula, the tidal volume and inspiratory pressure can be appropriately increased; If it is too thin, replace the cannula or sleeve; When CPAP or PEEP is used, even if there is less air leakage, the pipeline should be replaced.
⑤ Detaching: It is a common and serious complication of mechanical ventilation, which can be divided into three types according to the position of detachment: one is to move to the hypopharynx: you can hear the sound of air leakage during ventilation, and the position of detachment can be directly seen by laryngoscope. The other is esophageal displacement: its symptoms are abdominal distension, breathing sounds in the stomach, and no aerosol formation in the intubation when exhaling. The third is the mouth. Extubation has been established and tracheal intubation should be done again immediately.
In addition, low air pressure and insufficient mechanical working pressure will also cause low ventilation limit alarm. The air source should be replaced and the working pressure should be adjusted.
⑶ Patients trigger hyperventilation alarm: It is more common in patients with strong spontaneous breathing. When using IMV, PSV, SIMV, CPAP and other methods, due to the increase of spontaneous breathing frequency and breathing depth, the patient's spontaneous ventilation volume increases, triggering ventilation alarm. If there is high fever, pain, irritability or other stimulation, the patient can breathe faster. At this time, symptomatic treatment is mainly given, such as necessary cooling, analgesia and sedation.
(4) Improper ventilator setting triggers upper limit alarm:
① The upper limit of ventilation alarm is set too low; At this time, the patient has no discomfort, and the upper alarm limit should be reset.
② The TV or MV setting is too large, so the ventilation conditions should be re-checked.
③ The trigger sensitivity setting is incorrect, so reset it.
(4) When using Sigh, there is a short alarm, so it is unnecessary to handle it.
⑤ The MV meter shows an error, and the ventilation meter should be used for correction.
4. Pressure alarm:
(1) patient triggers high pressure alarm:
① The patient's cough, pain, lack of oxygen, secretion blockage, high temperature of inhaled gas and other stimuli cause discomfort. When he is restless, spontaneous breathing and mechanical breathing will trigger a high-pressure alarm. The above situation should be treated with sedation, and muscle relaxants can be used to "interrupt" the patient's spontaneous breathing if necessary.
② Pulmonary complications: When pneumothorax, atelectasis, lung inflammation aggravation, pulmonary edema, bronchospasm and other complications occur, lung compliance decreases, airway resistance increases, and pressure alarm may occur when ventilation methods such as volume control are used. The first two are related to the use and adjustment of ventilator and tracheal intubation, which are serious and common complications. X-rays can be found. In neonatal cases, pneumothorax can be found early through the light transmission test of closed thoracic drainage. Atelectasis is often caused by mucus plug or tracheal intubation inserted too deeply, and it is also a common ventilation complication. Therefore, in order to prevent atelectasis, we should strengthen the management of respiratory tract, fully humidify, replenish fluid in time, pat the back and suck sputum, often change the patient's position, chest physiotherapy and so on. In order to facilitate the discharge of secretions, and at the same time adjust the position of tracheal intubation.
When the lung inflammation is aggravated and complications such as emphysema, pulmonary edema and bronchospasm occur, pressure alarm may also occur due to the decrease of lung compliance. At this time, antispasmodic drugs can be applied to trachea or vein, mainly to treat primary disease and bronchospasm.
⑵ Ventilator catheter and other facilities trigger high-pressure alarm: ① The intubation is too deep and enters one side of the main bronchus (usually the right side), so the intubation should be readjusted according to the indicated depth of chest radiograph; ② stagnant water or secretion obstruction in the catheter: stagnant water in the catheter does not flow back to the patient's respiratory tract, but it is asymptomatic. Entering the respiratory tract will cause "flooding". Increase respiratory resistance and trigger high pressure alarm. Should be cleaned up in time. And observe whether there is airway spasm and calm down if necessary; ③ The blockage of ventilator pipeline and tracheal intubation itself, such as kink and discount, often causes ventilation alarm at the same time. You should leave the ventilator immediately and give oxygen to the airbag; Remove kinks and fold or replace the catheter; ④ The setting of high-pressure alarm is too low: patients often have no symptoms and need to reset the alarm limit; ⑤ Ventilator or catheter setting triggers low-pressure alarm: The main reasons are improper intubation model, broken catheter or loose connector leading to air leakage, accounting for about 1/3 of tracheal complications. The treatment method is the same as the low ventilation limit alarm caused by this reason.
13. oxygen concentration alarm:
(1) Low limit alarm: When the oxygen supply is insufficient, the oxygen battery is exhausted or improperly inserted, the newly replaced oxygen battery fails to get enough oxygen (usually within 24 hours) or the set value of the low limit alarm is too high, the oxygen concentration low limit alarm will appear. Its treatment is to give adequate oxygen supply; Replace the oxygen battery in time; The fresh oxygen battery can be exposed to air for 24 hours or 100% pure oxygen 1 hour before use; Reasonable setting of low limit alarm.
⑵ High limit alarm: When the compressed air pressure is insufficient, the air and/or oxygen pressure can't reach the working pressure of the ventilator, or the set value of the oxygen concentration high limit alarm is too low, the alarm system can be triggered. At this time, the pressure and proportion of air and oxygen should be adjusted, and the upper limit alarm value of oxygen concentration should be reset.
4. Power alarm:
⑴ Power alarm: It is caused by power interruption (such as fuse blowing, power cord falling off, power failure, etc.). ). Power failure outside the ventilator is easy to find and can be handled in time. In case the internal circuit of the ventilator fails, there should be special maintenance personnel to repair it. But at this time, it should be noted that when the above faults occur, the patient should be separated from the ventilator first, and then mechanical maintenance should be carried out.
⑵ Air source alarm: it shows that the working pressure of the ventilator is insufficient, which can be divided into: ① insufficient air pressure, such as the failure of the air compressor pump, which makes the air pressure fail to reach the working pressure. (2) The oxygen source is insufficient, and the oxygen pressure can't reach the starting pressure, such as oxygen exhaustion and low working pressure. , should adjust the pressure or change the air source in time.
⒌ Asphyxia alarm: It is common in patients with irregular breathing rhythm and poor spontaneous breathing, and it is easy to be found when assisted with mechanical ventilation. The treatment method is to actively deal with the primary disease and control the parallel mechanical ventilation.
In short, among the above alarm reasons, mechanical accidents account for more than 50%, and the factors from patients are the most important. The principle of handling the alarm state is: when a ventilator alarm occurs, if the alarm reason cannot be found out immediately or it is difficult to eliminate it for a while, the patient should be immediately separated from the ventilator and given oxygen by the airbag, and then the alarm reason should be checked before further treatment, as shown in the figure.