Overview of EMS Portable Ventilator Management
Emergency medical services are known to include many new procedures and treatments, but the traditional method of using a bag-valve-mask device for manual ventilation remains the standard in the US. This process requires a person to manually pump air and can sometimes result in inconsistent breathing rates and volumes of air inhaled.
In hospitals, mechanical ventilation, which is the use of a machine to assist with breathing, has been found to be effective and portable machines are available at a relatively low cost. The National Association of Emergency Medical Services Physicians in 2022 has encouraged more use of these mechanical ventilation devices before a patient arrives at the hospital.
However, many emergency medical services may not be using these ventilators because they are not familiar with the process of how our bodies breathe, which could make them less likely to suggest using a ventilator. In fact, according to the US National Emergency Medical Service Information System, ventilators are used by emergency medical services during the procedure of inserting a tube into a patient’s airway to assist breathing, less than 1% of the time.
Anatomy and Physiology of EMS Portable Ventilator Management
The breathing system, or respiratory system, is made up of different parts that help exchange gases. The upper airway includes parts like the nose, mouth, throat, and voice box. The main job of these parts is to warm, moisten, and clean the air we breathe in. The lower airway is made up of the windpipe, main air tubes (bronchi), and smaller air tubes (bronchioles). These parts carry air back and forth from the tiny air sacs (alveoli) in the lungs where the actual gas exchange happens.
Respiration, the process of breathing, involves two things: ventilation and perfusion. Ventilation is the movement of air between our environment and the air sacs in our lungs. Perfusion is the movement of blood through tiny blood vessels in the air sacs. The balance between these two processes is known as the V/Q ratio, which can influence how well oxygen and carbon dioxide are exchanged. While both diffusion (spreading out) and ventilation are needed to remove carbon dioxide, ventilation contributes mostly to this process. Ventilation also manages the speed and volume of a person’s breathing. How well the body is supplied with oxygen depends on the amount of oxygen in the alveoli, from where it quickly spreads into the blood vessels.
Even small changes in ventilator settings can have significant effects on a patient’s body. For example, applying positive end-expiratory pressure (PEEP), which increases pressure in the chest, can reduce the amount of blood the heart receives. However, the effects of PEEP are complex and can vary depending on factors like the patient’s fluid levels, how well the heart is working, and how severe the lung disease is. It’s crucial to adjust the fraction of inspired oxygen (FiO2) correctly because both low and high levels can be harmful. The rate and volume of the breaths given can be adjusted to maintain the correct levels of carbon dioxide in the body.
Using a mechanical ventilator, a machine that helps patients breathe, is an essential tool for out-of-hospital doctors and paramedics when treating critically ill patients with breathing problems. Having a solid understanding of the respiratory system and how to use a ventilator properly can significantly improve patient outcomes and contribute to their overall well-being.
Why do People Need EMS Portable Ventilator Management
If a patient is having trouble breathing on their own, a machine called a ventilator can be used to assist them. The ventilator is used in situations where the patient needs help getting air into their lungs, such as when they have a tube put down their throat (orotracheal intubation) or when they’re using a special type of mask (laryngeal mask airway ventilation). Providing a suitable ventilator can make the process more comfortable for the patient and they may cooperate better.
Some situations where a ventilator might be needed include if the patient is having respiratory failure (their body isn’t getting enough oxygen or removing enough carbon dioxide). The ventilator can alleviate these issues by lowering the effort it takes for the patient to breathe, managing the amount of air moving in and out of the lungs each minute, utilizing more lung tissue for oxygen exchange, and better matching air flow and blood flow in the lungs.
The National Association of EMS Physicians (NAEMSP) recommends the use of ventilators in emergency situations outside the hospital for patients who are experiencing respiratory failure or need help protecting their airway.
When a Person Should Avoid EMS Portable Ventilator Management
Using a breathing machine, known as a mechanical ventilator, requires a qualified and certified doctor or nurse to handle its settings safely. Even though there might not be clear benefits of using a ventilator for short travel periods, it’s not exactly forbidden or a bad idea.
Preparing for EMS Portable Ventilator Management
Before starting a machine that helps with breathing (mechanical ventilation) in a non-hospital setting, the patient needs to be properly given medicine for pain and relaxation. What is happening with the patient physically and why they need this help with breathing will guide how the machine is set up. Keeping oxygen and carbon dioxide at the right levels is important for good brain function and recovery. With a ventilation machine, it’s possible to better control these levels. Lack of oxygen in these non-hospital settings is often linked to bad recovery in trauma patients. But having too much oxygen can also increase the chance of death. So, doctors will adjust the level of pure oxygen (FiO2) to target a reading that says at least 95% of a patient’s blood is carrying oxygen.
When a patient is put on a ventilator to protect their airway, the machine should work like the patient’s normal breathing. If the patient doesn’t have enough oxygen in their blood, doctors may increase FiO2 and increase the slight pressure reached in the breath cycle (PEEP) to improve oxygen delivery. If the patient has too much carbon dioxide, they might not need a lot of extra oxygen. The best approach is to improve the ventilation to get carbon dioxide back to normal and use as little extra oxygen as possible. For a patient with a high level of acid in their body, it is important to match the total amount of air the patient was breathing naturally before they were put on a ventilator.
Setting up the ventilator: Most of the time, the settings for non-hospital care are based on what is usually done in the hospital. These settings should be applied as quickly as possible. A device used for short-term manual breathing (bag-valve-mask or BVM) might seem like a good option for short transports, but injury from using too much breath volume can happen quickly and it can increased the chance of death.
Choosing how the ventilator will work usually depends on what the doctor is comfortable with, and the local guidelines. This review only talks about a method called ‘volume assist’ or control, which is common to all ventilators.
The size of each breath, called ‘tidal volume’, is worked out based on the patient’s height and sex, not their actual weight. This is because the lungs do not get larger with body weight, and a man weighing 200kg will have a similar lung size to a man of the same height weighing 70kg. Therefore, it’s very important to measure the patient’s height or ask their family for it.
The following are common ways to work out the ideal body weight:
– For men: 50kg + (2.3kg times (height [in] – 60))
– For women: 45.5kg + (2.3kg times (height [in] – 60))
The starting breath rate for patients struggling to breathe is usually 14 to 16 times per minute, but a much higher rate may be needed for patients with a high level of acid in their body. The initial measure of carbon dioxide after the patient is put on the ventilator should be noted, and this measurement should be used to guide the amount of ventilation needed.
Setting the PEEP usually starts at 5cm H2O, enough to balance the resistance of the ventilator and maintain a normal physiology.
Often, the initial pure oxygen (FiO2) will be set to 100%, but too long at this level can lead to too much oxygen in the blood, which can have long-term effects on the patient. So, it’s recommended to reduce FiO2 quickly, using the smallest amount necessary to keep the reading for the oxygen in the blood between 92% and 98%.
Pain and relaxation medicine is necessary for the ventilator to work properly, make the patient comfortable, and avoid further injury to the lungs. The choice of medicine will depend on the local protocol.
How is EMS Portable Ventilator Management performed
For those needing help from a machine to breathe correctly, a procedure called mechanical ventilation is used. This can be done both in the hospital and even before the patient arrives at the hospital (prehospital care). This technique needs to be adjusted to fit the specific needs of the patient and their particular condition.
When using a ventilator, there are several key factors that help control and create a breath. These are:
- Tidal volume: The amount of air given in each breath, measured in milliliters (mL).
- Respiratory rate: The number of breaths given per minute.
- Minute ventilation: The total amount of air exchanged over 1 minute, calculated by multiplying the tidal volume by the respiratory rate. This is measured in liters per minute (L/min).
- Peak airway pressure: The highest pressure applied on the airways when you breathe in, measured in cm H2O.
- Flow rate: The speed of the air coming in needed to overcome the resistance of the circuit to deliver the breath, measured in liters per minute (L/min).
- I:E ratio: The comparison of the time you spend breathing in to breathing out.
- Fraction of inspired oxygen (FiO2): The percentage of oxygen in the air you’re breathing in.
- Positive end-expiratory pressure (PEEP): The airway pressure applied at the end of breathing out, measured in cm H2O.
Ventilators have different modes for helping with breathing that depend on how the breath starts, the targeted rate or pressure for breathing, and when the breath ends. Basically, there are three types of breaths used in mechanical ventilation:
- Mandatory: The ventilator initiates and controls the breath.
- Assisted: The patient starts the breath, but the ventilator does the work of breathing in.
- Spontaneous: The patient starts the breath and does the work of breathing in.
There are two main categories of mechanical ventilation strategies – volume control and pressure control – that depend on whether the goal is to achieve a particular volume or a particular pressure during the breath.
Additionally, each ventilator has different modes that vary based on how the breath begins, the breathing strategy, and the types of breaths used. Some of the common modes include controlled mechanical ventilation (CMV), assist or control ventilation (AC), pressure-regulated volume control (PRVC), intermittent mechanical ventilation (IMV), pressure support (PS), and continuous positive airway pressure (CPAP).
After starting the patients on mechanical ventilation, monitoring is very important to ensure that the settings are adjusted as needed. Clinicians often rely on two tools to make necessary changes. They are:
- End-tidal capnometry (EtCO2): It provides an estimate of the amount of carbon dioxide in the blood as it passes through the tiny air sacs in the lungs (alveoli). The ideal range is from 40 to 45 mm Hg.
- Pulse oximetry (SpO2): It provides a real-time monitor of the concentration of oxygen in the blood. The ideal range is 92% to 98%.
These tools can help track changes and adjust the ventilator settings in a way that best suits the patient’s needs.
Possible Complications of EMS Portable Ventilator Management
Under normal conditions, our chest helps us maintain healthy blood flow and regulates our blood pressure by creating a specific type of pressure. However, when a patient is placed on a breathing machine, or ventilator, this can alter the pressure and potentially lower blood pressure. This change may also happen due to medications used to make the patient relaxed or sleepy. Sometimes, the setting on the ventilator might accidentally be set too high and reduce blood pressure, but adjusting the setting can usually address the problem.
If a patient is on a ventilator and there are issues with oxygen levels or other signs of instability, doctors may need to temporarily remove the patient from the device to pinpoint the problem. During this time, healthcare professionals would use a manual device known as a bag-valve-mask to ensure the patient continues to receive oxygen. They will check to see if there’s anything blocking the device, check if the tube is placed correctly and ensure the patient’s chest is moving correctly with each breath. If all else fails, the clinicians will replace the monitor.
Patients who rely on ventilators must have their breathing machine settings managed carefully to keep their body’s internal chemistry balanced. If a patient’s carbon dioxide levels are rising, doctors will be on the lookout for issues, like fluid in the lungs or a collapsed lung among other things. In such cases, patients would be manually ventilated using a bag-valve-mask, and often the breathing rate or size of each breath needs to be increased on the ventilator settings. If levels of oxygen (a condition called hypoxia) suddenly drop, doctors will check for similar issues, give the patient more oxygen, and might increase certain settings on the machine itself. If the machine triggers a warning signal indicating that there’s too much pressure built up, clinicians will search for any blockages and might need to adjust the sedation level or other settings on the machine. They may also consider using medications to open up the patient’s airways if needed.
Patients on ventilators can sometimes face an issue known as “breath stacking,” which happens when they can’t exhale fully before taking a new breath, causing pressure to build up in the lungs. This condition is seen more in patients with severe lung diseases like asthma and can be harmful. To address this, doctors would disconnect the patient from the ventilator for a brief period, help the patient fully exhale, and then reconnect them. Changes would be made to the machine settings to ensure there’s enough time for the patient to fully exhale before taking the next breath. In some cases, doctors might allow a certain level of carbon dioxide buildup in the bloodstream, a condition known as “permissive hypercapnia,” in order to get the right oxygen levels and to prevent breath stacking.
Patients with a serious condition known as metabolic acidosis, often seen in diseases like diabetes, sometimes need extra help with their breathing to correct the increased acidity in their blood. If a ventilator is required, doctors would aim to match the patient’s natural breathing rate. They would also keep a close eye on the carbon dioxide levels in the body, working to maintain or lower them as necessary to prevent the condition from worsening.
Patients suffering from acute respiratory distress syndrome, a severe lung condition characterized by inflammation and injury, need specialized care when on a ventilator. The settings on the machine would be adjusted to provide small breath volumes with increased levels of oxygen and positive pressure. In such patients, slightly lower oxygen levels are usually acceptable due to the small breath volume. This condition is hard to diagnose outside hospital settings; however, a high need for oxygen can be a sign of this syndrome.
What Else Should I Know About EMS Portable Ventilator Management?
When a patient needs help with their breathing (intubation) outside a hospital setting, they’re often given artificial ventilation – a way to push air into their lungs. This is usually done with a device called a bag-valve-mask, which a healthcare provider uses to manually squeeze air into the patient’s lungs. However, this method can be unpredictable and requires continuous attention from the healthcare provider.
These days, a machine called a mechanical ventilator is used to maintain steady and reliable breathing, especially during longer patient transports. A ventilator allows the healthcare provider to adjust the breathing settings of the air given to the patient with great precision. This entails understanding the basics of how breathing works as well as how to use the ventilator.
It’s also important to highlight that incorrect use of the ventilator can make the patient’s condition worse. It can make the original breathing problem worse and might trigger a harmful response from the body’s immune system, leading to additional lung damage. Therefore, proper management of a ventilator is vital when caring for a patient who is having trouble breathing.
