Rescuer Technique for Providing Airway Impedance Threshold
- November 9, 2016
- Posted by: marlenedubois
- Category: CPR Training
The physiology of cardiac arrest is usually based upon the thoracic pump theory. As the chest is usually compressed, pressure within the chest cavity is usually increased. When the chest recoils in addition to returns to its natural position, pressure within the chest cavity decreases; of which is usually, the pressure within the chest cavity returns to a “pre-compression” level. In essence, with each compression/recoil sequence, pressure within the chest cavity is usually constantly alternating with an increase-decrease fluctuation. This kind of alternating change in pressure subsequently creates a positive-negative pressure gradient within the circulatory system, resulting in cardiac output. With each chest compression (positive pressure), blood is usually ejected through the heart (after load); with each chest recoil (negative pressure), blood is usually drawn into the
Another factor in optimizing cardiac output is usually control of the ventilation rate. Ventilations should be delivered at a rate of 10-12/minute. A ventilation rate greater than 10-12/minute produces an increase in intrathoracic pressure which, in turn, creates a mismatch from the positive-negative pressure gradient. The increased intrathoracic pressure inhibits blood flow into the
Due to alternating intrathoracic pressure adjustments, a vacuum is usually essentially created within the chest cavity during
In recent years, completely new technology has emerged which focuses on increasing cardiac output by decreasing intrathoracic pressure in addition to so enhancing the positive-negative pressure gradient within the chest cavity. The impedance threshold device is usually a device which is usually placed within the respiratory circuit, between the bag-valve resuscitator in addition to an airway adjunct, such as an endotracheal tube or supra-glottic airway. The device incorporates a spring-controlled valve which allows ventilated air to enter the respiratory system, however prevents passive air, which flows through the bag-valve resuscitator between ventilations, through entering. Essentially, when the bag-valve resuscitator is usually compressed, air pressure at 30 cm./H2O is usually exerted upon the spring controlled valve of the impedance threshold device. The valve opens, allowing ventilated air to enter into the respiratory tract. The valve then closes. Although the passive air passing through the bag-valve resuscitator exerts pressure upon the spring controlled valve, the pressure is usually much less than 30 cm./H2O in addition to therefore not high enough to cause the valve to open. In essence the passive influx of air between ventilations is usually prevented through entering the respiratory tract. This kind of, in turn, prohibits an unwanted increase in intrathoracic pressure, in addition to enhances the positive-negative pressure gradient within the chest cavity, thus increasing cardiac output.
Several Emergency Medical Service systems utilizing impedance threshold devices from the management of cardiac arrest have reported increases in successful cardiac resuscitation to be 50% higher than previous efforts. Studies have suggested perfusion to the brain to be 70% higher while utilizing an impedance threshold device as opposed to 25% without utilization of the device (1).
Although impedance threshold devices have demonstrated a definite enhancement of the intrathoracic positive-negative pressure gradient in addition to so enhanced outcome in cardiac arrest survival, they remain somewhat cost prohibitive for several EMS systems. The impedance threshold device is usually one particular use device in addition to retails for approximately $99. Most would certainly argue however, of which This kind of is usually a tiny cost to pay if of which contributed to a higher successful cardiac resuscitation rate.
If the rescuer ventilating the patient were to disconnect the bag-valve resuscitator through the circuit, of which is usually, the endotracheal tube or supra-glottic airway, in addition to then place his or her thumb over the endotracheal tube or supra-glottic airway adapter, thus occluding the airway in addition to preventing the influx of passive air into the respiratory tract between ventilations, the same airway impedance effect would certainly occur. Essentially the rescuer would certainly ventilate the patient by compressing the bag-valve resuscitator, disconnect the bag-valve resuscitator, place their thumb over the airway adapter, thus occluding the airway, for 4-5 seconds, reconnect the bag-valve resuscitator, in addition to repeat the sequence. This kind of action would certainly require both vigilance in addition to discipline on the part of the rescuer. Vigilance in ensuring of which the bag-valve resuscitator was carefully disconnected without dislodging in addition to subsequent misplacement of the endotracheal tube or supra-glottic airway. Discipline in ensuring the continuous sequence of ventilation, disconnection of the bag-valve resuscitator, occlusion of the airway for 4-5 seconds, in addition to reconnection of the bag-valve resuscitator to the airway circuit. The challenge for the rescuer is usually to maintain This kind of sequence consistently, which may be difficult due to the dynamics of cardiac arrest management.
from the event of a return of spontaneous circulation, respiratory arrest, or assisted ventilation via bag-valve resuscitator for the patient having a pulse, This kind of thumb impedance threshold protocol would certainly not be utilized, as of which is usually only effective from the resuscitation effort to restore a pulse in a pulse-less patient.
Although of which has its challenges in addition to limitations as compared to the mechanical impedance threshold device, utilization of the rescuer applied thumb impedance threshold technique would certainly be an inexpensive, yet effective means of enhancing the intrathoracic positive-negative pressure gradient. This kind of would certainly, in turn, increase cardiac output in addition to improve the chance of successful resuscitation secondary to cardiopulmonary arrest.