In modern medicine, artificial lung ventilation (ALV) devices play a crucial role in sustaining the lives of patients with various types of respiratory failure.
The basic operating principles of such devices are based on several key concepts and technologies that ensure effective and safe ventilation:
Positive Pressure Principle
The ALV device operates on the principle of creating positive pressure, which facilitates the entry of air or gas mixtures into the patient’s lungs. The device ensures that air enters the airways, preventing alveolar collapse and maintaining proper gas exchange.
Ventilation Based on Controlled Variables
Artificial lung ventilation devices use three key controlled variables that determine the ventilation modes: pressure-based ventilation, volume-based ventilation, and combined ventilation that integrates both approaches.
Pressure-Based Ventilation: In this mode, the device maintains a set level of pressure in the patient’s airways. This helps ensure proper alveolar expansion and adequate gas exchange, which is critical for patients with various respiratory pathologies. This approach helps to avoid excessive pressure on the lungs, which could lead to tissue damage.
Volume-Based Ventilation: This mode delivers a specified volume of air with each breath, allowing for control over ventilation parameters and ensuring stable gas exchange. This approach is particularly useful for patients who require maintaining a consistent tidal volume.
Combined Pressure and Volume-Based Ventilation (known as "PRVC - Pressure Regulated Volume Control"): This method combines the advantages of both previous approaches, allowing for simultaneous control of pressure and volume. It provides an adaptive approach to ventilation, where the device automatically adjusts parameters based on changes in the patient’s condition. With this mode, physicians can implement lung protection strategies, adjusting to the patient’s lung compliance with each breath, minimizing the risk of complications.
Flow Sensors
ALV devices utilize two main types of flow sensors—"Hot Wire" and "Different Pressure"—for accurate measurement of flow and pressure within the circuit.
Hot Wire Sensors, located inside the exhalation valve, operate by heating a wire and measuring temperature changes, which allows precise tracking of the gas mixture flow rate. This type of sensor provides stability and durability, which is crucial for high-quality respiratory support.
Different Pressure Sensors measure the pressure difference between two points in the respiratory circuit and are the most accurate among sensors. They can be installed either distally or proximally in the patient’s circuit, depending on the patient’s type.
To ensure optimal respiratory support conditions, ALV devices should offer the ability to select appropriate sensors depending on the patient’s type.
Modern artificial lung ventilation (ALV) devices utilize various functions and ventilation modes to provide optimal respiratory support:
Ventilation Modes: ALV systems offer a range of ventilation modes, including Continuous Mandatory Ventilation (CMV), Synchronized Intermittent Mandatory Ventilation (SIMV), and Spontaneous Ventilation (SPONT). This allows doctors to select the optimal mode according to the patient's needs, taking into account their clinical condition and the required level of respiratory support.
Ventilation Parameter Control: ALV devices continuously monitor key parameters such as airway pressure, tidal volume, respiratory rate, and more. These indicators allow physicians to adjust the ventilation mode to ensure optimal support.
Data Monitoring and Visualization: ALV devices are equipped with capabilities to display respiratory cycle graphs, trends, and color-coded signals on screens. This enables doctors to easily track respiratory dynamics and adjust ventilation parameters in real time. For example, graphical displays of spontaneous and mechanical breathing provide an accurate analysis of lung function.
Automatic Control: Modern ALV devices are equipped with automatic control functions, allowing the device to independently adapt to the changing respiratory conditions of the patient.
Safety and Accuracy: Critical aspects of safety include monitoring oxygen saturation (SpO2), volumetric capnography (VCO2), and sidestream capnography (etCO2), among other modern methods. These functions enable doctors to ensure proper oxygenation, prevent potential complications, and monitor changes in gas exchange.
Each artificial lung ventilation (ALV) system offers a range of unique features aimed at enhancing the efficiency of ventilation and ensuring comfort for both patients and medical staff. Of particular note are the ALV devices from Event Medical, designed to provide high-level support for patients weighing as little as 200 grams.
An important feature is the ability of these devices to operate both from a built-in turbine and from a centralized compressed air supply system or compressor, making them versatile for various medical settings.
Innovative approaches to patient monitoring have also become a significant part of these ALV systems. The primary objective is to implement protective ventilation strategies based on monitoring various critical indicators.
Monitoring "Driving Pressure" or real-time ventilation pressure, stress index (SI), and the impact of the ALV device on the patient optimally distributes the risk of lung injury caused by mechanical ventilation (known as Ventilator-Induced Lung Injury or VILI), such as volutrauma (lung damage due to excessive air volume) and barotrauma (damage due to excessive pressure).
A crucial aspect is the monitoring of esophageal pressure, which allows for the assessment of transpulmonary pressure and lung elasticity, key to ensuring safe ventilation.
One of the key advantages is the adaptive (intelligent) mode function, which automatically transitions from full ventilation support to spontaneous (assisted) ventilation with gradual reduction of mechanical aid from the device. This feature is particularly important in the process of weaning the patient off the ventilator.
Thanks to technological advancements, artificial lung ventilation devices are becoming increasingly accessible and safer. Today, there is a wide range of ALV systems, but the main feature is their versatility and comprehensive respiratory support, including both invasive and non-invasive ventilation for patients of all age groups.
