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Parameter setting of ventilator

2016/1/19      view:

A tidal volume, the ventilator settings

      Is the set tidal volume mechanical ventilation should be first considered. Volume control ventilation, tidal volume, the goal setting is to ensure adequate ventilation, and make patients more comfortable. Adult tidal volume is 5 ~ 15ml/kg, 8 ~ 12mg/kg range is the most commonly used. Tidal volume setting should consider the following factors: lung conform to the compression volume and oxygenation, ventilation function and the risk of barotrauma, airway resistance and the ventilator tube. Barotraumas ventilator associated damage is caused by improper application of mechanical ventilation, tidal volume setting process, in order to prevent the occurrence of barotrauma, the general requirements of the plateau airway pressure does not exceed 35 ~ as 40 cmH2O. The pressure control ventilation, tidal volume size is mainly determined in a preset pressure level, patient inspiratory force and airway resistance. In general, the tidal volume level should not be higher than 8 ~ 12ml/kg.

Two, the frequency of mechanical ventilation

      The frequency of mechanical ventilation in the ventilator set should consider ventilation, tidal volume size, die cavity rate, metabolic rate, arterial carbon dioxide points target level and in patients with spontaneous breathing capacity pressure and other factors. For adults, mechanical ventilation frequency can be set to 8 to 20 times per minute. For patients with acute and chronic restricted ventilation dysfunction, mechanical ventilation should be set high frequency (20 beats per minute or more). Mechanical ventilation for 15 to 30 minutes, according to arterial oxygen partial pressure, carbon dioxide partial pressure and pH value, into a mechanical ventilation frequency adjustment. In addition, the setting of the mechanical ventilation frequency should not be too fast, so as to avoid the closing of the gas in the lung and the positive end expiratory pressure. Once the positive end expiratory pressure is generated, it will affect the pulmonary ventilation / blood flow, increase the respiratory function of patients, and increase the risk of air pressure injury.

Three, the ventilation rate of breathing machine settings

      Many breathing machine needs to set inspiratory flow rate. The setting of inspiratory flow rate should pay attention to the following problems:

1 volume control / auxiliary ventilation, such as patients with no spontaneous breathing, the inspiratory flow rate should be less than 40 liters / min, such as patients with spontaneous breathing, the ideal inspiratory flow rate should just meet the needs of the patient's inspiratory peak flow. According to the patient the suction size and minute ventilation, the inspiratory flow rate to 40 ~ 100 liters / min. Due to the magnitude of the inspiratory flow rate will directly affect the patient's respiratory work and man-machine coordination, should attract the attention of clinicians.

2 pressure control ventilation, peak inspiratory flow rate is determined by the preset pressure level and the patient's suction force, of course, the maximum inspiratory flow rate is limited by the performance of breathing machine.

Four, breathing machine suction ratio settings

During mechanical ventilation, the ventilation ratio of breathing machine should be taken into account in the effects of mechanical ventilation on hemodynamics, oxygenation status, and the level of spontaneous breathing.

1. The existence of the spontaneously breathing patient and ventilator assisted breathing, ventilator aspirated should match and the patient inhale to guarantee the synchronization of the two. General suction need 1.2 ~ 0.8 seconds, suction call ratio is 1: 2 ~ 1: 1.5.

2 for patients with controlled ventilation, the general inspiratory time is longer, the suction call is higher, can improve the average airway pressure, improve oxygenation. However, it should be noted that the change of hemodynamics of patients should be paid attention to.

3 inspiratory time is too long, the patient is not easy to tolerate, often need to use a sedative, and even muscle relaxing agent. Moreover, a short expiration time can lead to positive end expiratory pressure, increase the disturbance of the cycle. Attention should be paid to the clinical application.

Five, the ventilation mode of the ventilator settings

      Many of the breathing machine has a variety of air flow modes to choose. The common modes of airflow are slow down, accelerated flow, Fang Bo flow and sine wave. Air flow mode selection is only suitable for volume control ventilation mode, pressure control ventilation, ventilation are provided to slow down the airflow, so that the airway pressure quickly reach the set pressure level. In volume controlled ventilation, the airflow pattern comparison research is less, from the point of view of existing data, when the tidal volume and inspiratory time / breathe at the same time, effects of different flow patterns in patients with ventilation and work of breathing in are similar. Of course, the volume control ventilation, the habit will be set in the air flow mode. The effects of different airflow patterns on the patients should be further studied and observed.

Six, the oxygen concentration of breathing machine settings

      In mechanical ventilation, the oxygen concentration of breathing machine is generally determined by the target level of arterial oxygen partial pressure, positive end expiratory pressure, mean airway pressure and hemodynamics. Due to the high concentration of oxygen inhalation can produce oxygen toxic lung injury, the general requirements of the inhalation of oxygen concentration of less than 50% ~ 60%. However, it should not only take into account the effects of high concentration of oxygen on the lung injury, but also consider the role of airway and alveolar pressure in the lung injury. For patients with severe oxygen disorder, should be in full sedation and muscle relaxation, the use of appropriate levels of positive end expiratory pressure on the premise, set the absorption of oxygen concentration, so that the arterial oxygen saturation of 88% ~ 90%.