Can a Ventilator on Anesthesia Replace a Dedicated Ventilator?
Can a Ventilator on Anesthesia Replace a Dedicated Ventilator?
After the outbreak of the epidemic abroad in March this year, the demand for ventilators increased significantly. Faced with a large demand from abroad, domestic respirator manufacturers have reached saturation in production capacity but still cannot meet the strong demand. So much so that many people pay attention to anesthesia machines, which are also equipped with ventilators and have similar breathing patterns. Can anesthesia machines replace ventilators? Let's take a look at the differences and commonalities between the two:
1. Breathing pattern
This should be the first difference that comes to mind. Generally, breathing is divided into autonomous breathing, assisted breathing, and controlled breathing. Due to the use of muscle relaxants, anesthesia machines almost always control the breathing mode (VCV, PCV, PCV-VG, etc.), while the main mode of ventilation is assisted and autonomous breathing is dominant (SIMV, CPAP, etc.). Fortunately, most high-end anesthesia machines nowadays are equipped with SIMV mode, and the breathing mode of anesthesia machines has been borrowed from the application of ventilators in clinical anesthesia for many years. Even if it is not available, it can be upgraded to breathing mode through software configuration. Of course, due to the different internal gas pathways of the two machines, it is difficult for anesthesia machines to fully achieve all the functions of ventilators.
2. Humidifier
The humidifier is a prominent mark on the ventilator, and the consumables for the tubing are also different. Due to the short duration of most surgeries, anesthesia machines are often not equipped with humidifiers and instead use artificial nose moisturizers. A humidifier is usually placed between the inhalation valve and the patient. The exhaled gas condenses and accumulates in a water cup on the exhalation pipeline. The carbon dioxide absorbent is located upstream of the humidifier and only passes through sodium lime during inhalation, so the humidifier will not cause significant loss of absorbent.
3. Fresh air flow regulation
The ventilator is an open circuit, and all exhaled gases are excreted; The anesthesia machine is a semi closed circuit, and some of the gas will be reabsorbed. The decrease in the air box reading is the amount of gas that is reabsorbed (actually a mixture of exhaled and fresh air). Since the carbon dioxide in the re inhaled gas will be absorbed by soda lime, it is recommended to use the middle note high-tech fresh gas flow to reduce the re inhaled gas, so as to reduce the consumption rate of soda lime; Based on this speculation, the use of anesthesia machines may save more oxygen than ventilators.
COVID-19 mainly invades the lungs and forms serious ARDS. Respiratory treatment is the core measure; The anesthesia machine can approach the ventilator in breathing mode, but the differences still exist, such as SIMV, which may have fewer adjustable parameters on the anesthesia machine; For example, in monitoring respiratory mechanics, ventilators are significantly better than anesthesia machines. Although the differences are still significant, replacing a ventilator with an anesthesia machine is a transitional measure to save as many patients as possible when non ventilatored patients may face death.
