1, assisted / control mode (A-CV): assisted ventilation (AV) and control ventilation (CV) the combination of two modes.
When the patient's self-help respiratory rate is lower than the preset frequency or the patient's inspiratory effort cannot trigger the ventilator to deliver air, the ventilator that is, the ventilator is positive-pressure ventilation at the preset tidal volume and ventilation frequency, i.e., CV; when the patient's inhalation can trigger the ventilator, the ventilation is performed at a higher frequency than the preset frequency. Volume-controlled mode, a commonly used mode of ventilation for adults, ensures ventilation; pressure-controlled ventilation (PCV) is commonly used by pediatric patients, with constant pressure, which is less likely to result in pneumatic injuries to the lungs.
2. Synchronized Intermittent Command Ventilation (SIMV): a respiratory mode that combines voluntary breathing with controlled ventilation.
The advantage is to ensure ventilation, but also conducive to exercise the respiratory muscles, more commonly used, often as a withdrawal of the machine before the excessive measures.
3. Pressure Support Ventilation (PSV)
After the patient's voluntary respiration triggers the ventilator, the ventilator gives the patient a certain amount of pressure support to achieve the purpose of improving ventilation, which is a ventilator-assisted mode of voluntary ventilation with good synchronization, and it can be used together with SIMV.
4, continuous positive airway pressure ventilation (CPAP)
is the patient in the independent breathing based on the ventilator in the inhalation and exhalation of both phases are given a certain pressure, so that the alveoli open, applicable to the decline in lung compliance and pulmonary atelectasis, obstructive sleep apnea syndrome and so on.
5. Positive end-expiratory pressure ventilation (PEEP)
In the expiratory still maintain a positive pressure in the airway, at a predetermined level of positive pressure, generally advocate that the terminal positive pressure of 5-10cmH2O. because normal people in the end of expiration due to the closure of the vocal folds, but also to maintain a certain amount of positive pressure, known as the physiological PEEP, generally between 1-3cm water column , mainly to maintain functional residual air volume and prevent alveolar atrophy. The patient loses this physiological protection after tracheal intubation, so PEEP of 1-3 cmH2O can be used during mechanical ventilation, but it should not be too high to prevent alveolar and pneumatic injuries, and this mode is mainly used in patients with ARDS and pulmonary edema.
As a vehicle ventilator, the function is relatively simple, fixed-volume ventilation mode is better in guaranteeing ventilation, more choose CV or SIMV mode, for cardiopulmonary resuscitation, severe respiratory center inhibition of patients should be preferred, in the neuromuscular disease and airway obstructive disease, SIMV is the most applicable mode.
When the preset frequency is sufficient to control spontaneous respiration, the frequency is equivalent to CV continuous command ventilation, and its intermittent command ventilation function is used for patients with a certain degree of spontaneous respiratory ability, and lung parenchymal or interstitial lung disease, prone to human-computer confrontation, need to be appropriate use of sedation and muscle relaxant, and for cases such as ARDS, the addition of PEEP as appropriate. PPV has the function of pressure-controlled ventilation and synchronization at the same time, which has advantages in gas exchange, mechanical ventilation-related lung injury and circulatory function, and is more suitable for lung parenchymal diseases, but affected by the sensitivity of the ventilator.CPAP is autonomous ventilation, and is suitable for the patients with strong autonomous respiration. When oxygen saturation is still low after the selection of the above modes and parameters, oxygen concentration can be increased for a short period of time, and then adjusted after the oxygen saturation improves.
P1V1/p2=volume. 1000*10/1=1000L.
Volume=minute ventilation x oxygen concentration.
Minute ventilation = respiratory rate x tidal volume.
The ventilator measures the patient's tidal volume to be 500 ML, respiratory rate to be 16, and minute ventilation to be 8 L. Oxygen concentration is 50%, so 1000/4 = 250 minutes.
But the oxygen cylinder management requirements are to leave more than 0.05MPa residual pressure, that is, you can not use up, so the time will be less than 2 to 3 minutes.
About 4-4.5 hours.
Because the patient's ventilator parameters are adjusted according to the patient's condition during transport, this value can only be approximate.
Instruments and equipment: ventilator, cardiac monitor, defibrillator, portable ventilator (Myriad SV300), vehicle-carried simple negative pressure suction, disposable suction tube.
1, line fixation
2, airbag management
3, airway humidification
4, sputum suction related issues
Assessment of the need for sputum suction indications
( 1) sputum sounds or sputum spilling out of the mouth of the catheter on auscultation at the bedside or in the lungs;
( 2) the awake patient's initiative to indicate "suction";
( 3) frequent choking and cyanosis in the patient;
( 4) a decrease in finger-prick oxygen saturation (SPO2), excluding decreases due to a change in the patient's condition;
( 5) a change in the parameters of the vehicle ventilator/increase in airway pressure and increase in the rate of spontaneous respiration, excluding other causes;
( 6) Comprehensive assessment and suctioning as needed.
Artificial airway suctioning
( 1) Strictly follow the aseptic procedure;
( 2) Prepare 2 bottles of sterile saline,
( 3) Adjust the ventilator to give inhalation of 100% pure oxygen for 1 ～ 2 min prior to suctioning;
( 4) Attach disposable sputum suction tubing to the suction device and turn on the suction device to adjust the suction pressure ( 80 ～ 120 mmHg). 80～120 mmHg), the front end of the suction tube is lubricated with saline and inserted into the tracheal tube;
( 5) Insertion depth is extended by the length of the tracheal tube by 1～2 cm;
( 6) Suctioning method: the suction tube enters at positive pressure to the marked depth, and then intermittently lifts up and rotates out at negative pressure;
( 7)? Each continuous suction time <15 s;
( 8) After sputum suction, pure oxygen inhalation was given for 2 min.
Artificial airway humidification method: In the hospital, the ventilator was used as a thermostatic humidifier, and in the transit, a disposable sterile syringe was used to extract 0.45% sodium chloride solution, and 3-5 mL of sodium chloride solution was dripped into the catheter at intervals of 30-60 min, with the intervals and the amount of drips adjusted appropriately according to the viscosity of the patient's sputum. The interval and the amount of drops should be adjusted according to the viscosity of the patient's sputum. Accurately measure and record the exposed length of the tracheal tube, closely observe and measure the exposed length and detect the pressure of the airbag every hour.
( 1) The number of sputum suction per hour (suction frequency) was recorded for all patients in the hospital and in transit, and the number of sputum suction in the hospital was recorded from the beginning of mechanical ventilation;
( 2) The number of cases of tracheal tube dislocation, and the number of cases of tracheal tube dislocation were recorded for the patients in the hospital and in transit respectively;
( 3) Sputum viscosity was scored as follows: 0, thin, no sputum in the suction tube, no sputum in the suction tube, no sputum in the suction tube, no sputum in the suction tube, no sputum in the suction tube, and the sputum in the suction tube. ( 3)The viscosity of sputum was scored as follows: 0 points, thin sputum, no crusts in the suction tube, easy to suction out; 1 point, thin sputum, no crusts in the suction tube, easy to suction out; 2 points, sputum with a certain degree of viscosity, no crusts in the suction tube, easy to suction out; 3 points, sputum is thick, there are crusts or sputum clumps in the suction tube, and it is difficult to suction out. The sputum consistency was scored before the start of the transfer and at the end of the transfer.
Suction management is an important part of ensuring airway patency and reducing associated complications. Endotracheal tube suctioning has the potential for a range of adverse effects and complications, and the technique and frequency of suctioning is an important factor in the occurrence of associated complications, so in view of the above considerations, we should minimize the number of times of sputum suctioning and avoid routine suctioning. We advocate "on-demand suctioning", selecting the timing of suctioning according to the changes in the patient's peripheral oxygen saturation, by auscultation or by observing the patient's respiration;
The fixation of tracheal catheters is currently used in China by the homemade adhesive tape fixation method, which is particularly prone to change the position of the catheter during the transfer process. The exposed length of the tracheal tube should be measured and recorded accurately before the transfer, and the exposed length and pressure of the air bag should be measured hourly during the transfer to understand the position of the tube, and adjusted in time if there is any change;
In terms of airway humidification, the patient loses the warming, humidifying, and filtering effect of the upper respiratory tract on the inhalation of the gas after the establishment of an artificial airway, and in view of the special therapeutic environment, the car-carried portable ventilator does not have a humidifying function. Ventilator does not have a wetting function, we can choose to intermittent airway drops of humidifying liquid to deal with.
First of all, analyze the causes of human-computer confrontation, the patient side of the causes of hypoxia, metabolic acidosis, acute left heart failure or infusion of too much fluid, lung injury or infection aggravation, lung tissue hyperinflation aggravation, secretion blockage, airway edema or spasm, airway reactivity enhancement, change in respiratory frequency, coughing, changes in body position;
Ventilator side of the causes of ventilator synchronization, ventilator connection, artificial airway can increase resistance, whereas mask or nasal mask ventilation and tracheotomy add little airway resistance, favoring shorter trigger times and improved synchronization, tube leakage affects function, and waterlogging of the connecting tubing, which interferes with triggering;
Airway-related causes are inappropriately sized or positioned intra-endotracheal tubes, leaky air sacs, excessive pressure in the air sac, and blocked tubes, displacement of the cannula, etc.
Transitional measures should be taken by giving high concentration oxygen therapy, transitioning to mechanical ventilation with either an autonomic mode of ventilation or an improvised ventilator to relieve the patient of the probable causes listed above, adjusting the breathing pattern, managing the tubing, and replacing the endotracheal tube if necessary, and if this does not improve, consider sedation and inotropic medications. The upper pressure limit should be set at 35 mmH2O, and SPaO2 and blood pressure should be closely observed to prevent pneumatic injury and ventilator-associated hypotension.
1, oxygen concentration
Calculation formula: 21 + 4 * oxygen flow. Low concentration of oxygen (24- 40%), for COPD patients; medium concentration of oxygen (40-60%) for hypoxia and carbon dioxide storage; high concentration of oxygen (more than 60%) for CO poisoning, cardiogenic shock and severe trauma after major surgery, inhalation of high concentration of oxygen should not exceed 1-2 days, otherwise easy to oxygen poisoning.
2, tidal volume
Generally set to 8-10ml/kg, for ARDS, pulmonary edema, pulmonary atelectasis and other poor lung compliance can be set at 10-12ml/kg, the maximum available to 10-15/ml/kg.
3. p> 3. Respiratory rate
Generally choose 8-14 times/minute, if the patient is allowed to adapt gradually before withdrawing the machine, the respiratory rate can be reduced to 2-10 places/minute.
4, inhalation / exhalation time ratio
Obstructive ventilation disorder inhalation: exhalation for 1:2-2.5, and with a slow frequency; restrictive ventilation disorder, inhalation: exhalation for 1:1.5, and with a faster frequency.
5. Pressure support
Set this parameter when using the pressure support ventilation mode, mild lesions in the lungs: 15-20 CMH2O; moderate lesions: 20-25 cmH2O; and severe lesions: 25-30 CMH2O.
Patients with COPD should have a lower tidal volume and a slower respiratory rate. Acute airway obstruction, such as bronchial asthma, in order to relieve severe hyperventilation, a lower tidal volume should be used (6 to 8 ml/k g or lower).Those who have only one side of the lung, the airway ineffective lumen is significantly reduced, a small tidal volume should be chosen, and the respiratory rate should be controlled at about 10 breaths/min. Inspiratory and expiratory time ratio: generally set between 1:1.5 and 2, for patients with COPD and bronchial asthma, the inspiratory and expiratory ratios can be between 1 and 2.5, and for patients with restrictive ventilation dysfunction, the inspiratory and expiratory ratios should be set between 1 and 1.5. The upper limit of pressure control is often set at 35 mmH2O, and PEEP is often set at 3 to 5 mmH2O.
References:
1. Clinical Application of Ventilator. Chinese people's **** and national health industry standards.
2. Liao Yasha. Analyzing the artificial airway management of 114 mechanically ventilated patients in long-distance transit[J]. Journal of Sichuan North Medical College.2017, 32(2).
3. Xie Junqing. Clinical application of vehicle-mounted ventilator[J]. Journal of Internal Medicine Acute and Critical Care.2017,13(6).