Introduction:
Mechanical ventilation is an advanced technology with extremely restricted therapeutic limits; it is highly effective and capable of keeping the sickest patients alive, but it can also have significant side effects and unwelcome consequences if it is not utilized properly and on time. There has been significant progress in improving the benefit-to-risk ratio of mechanical ventilation and the fact that too many patients are still ventilated using risky conditions like high tidal volume and airway pressure.
What Is Closed-Loop Control of Mechanical Ventilation?
Closed-loop control of mechanical ventilation is a method that uses information about a patient's breathing to adjust the ventilator settings automatically. It monitors the lungs' compliance and resistance, which are the properties that affect how easily air can flow in and out of the lungs. Based on this information, the ventilator modifies the pressure and volume of air delivered to the patient to achieve a target level.
Mechanical ventilation is under closed-loop control, which modifies settings in response to patient breathing. It measures and compares gas flow and pressure, making adjustments for stable breathing. It includes lung protection strategies. Initially, a mode called mandatory minute ventilation (MMV) was used, but it had limitations. Later, closed-loop control ventilation with optimal targeting was created to ease breathing and minimize strain. It can be used during different stages of ventilation. It provides the appropriate assistance by modifying ventilator settings dependent on the patient's breathing.
What Is the Mechanism of Closed-Loop Control?
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Closed-loop control ventilation requires patient information like age, gender, height, and ideal body weight.
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The ventilator calculates the patient's ideal body weight and displays it.
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Based on the patient's weight, the doctor sets the target minute ventilation, which establishes how much air the patient should inhale each minute.
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Parameters such as positive end-expiratory pressure and inspired oxygen levels are also set.
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A maximum pressure alarm is set as a safety measure.
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The ventilator calculates optimal ventilation settings based on the patient's lung characteristics to make breathing easier.
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The patient's breathing is guided within a safe range.
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The ventilator offers support by breathing more deeply or altering pressure if the patient's breathing falls outside of this range.
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Closed-loop control helps prevent excessive air volume or pressure, reducing the risk of lung damage.
What Are the Operating Principles of Closed-Loop Ventilation?
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When using mechanical ventilation, the closed-loop control mode complies with lung safety measures.
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Inhalation pressure, tidal volume, respiratory rate, inspiratory and expiratory times, and I:E ratio are only a few of the parameters that are subject to restrictions.
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These limits prevent complications such as lung overstretching, pressure-related injuries, and inadequate ventilation.
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Based on particular operational principles, the upper and lower limitations are automatically determined.
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The clinician sets a target percentage of minute ventilation based on the patient's ideal body weight.
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Other settings like positive end-expiratory pressure, oxygen levels, and maximum pressure alarm are also considered.
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Minute ventilation is calculated by dividing the ventilation required for the ideal body weight by the set percentage.
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Based on the optimal body weight, the ventilator determines the amount of dead space.
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The respiratory pattern, including respiratory rate, tidal volume, and inspiratory-to-expiratory time ratio, is selected to optimize breathing efficiency and reduce respiratory workload.
Why Do We Need Closed-Loop Systems for Mechanical Ventilation?
Humans' brains can only integrate a finite amount of data and knowledge before making decisions. This capacity is considerably worse at night, when stressed, or when time is of concern. This stands in contrast to "real ICU life," when caretakers must integrate hundreds of factors and make judgments 24 hours a day. This is especially true when it comes to mechanical ventilation. The disparity between human capacity and the enormous amount of data and information that must be absorbed undoubtedly adds to clinical practice's variability and may eventually provide an explanation for some errors and mistakes in medicine. A benchmarking model of safety management is now used in the aviation business, which has a less complex environment than other industries.
Finally, as patients get more complex, it can be difficult to continuously adjust the ventilator to the patient's condition when professionals are not always present at the bedside. In order to make mechanical ventilation as safe as possible, it seems essential to continuously modify the ventilator settings on a breath-by-breath basis. This is because the lung could be damaged with one mechanical breath. In a recent study, patients were ventilated with optimal ventilation just 12% of the time during a 4-hour period of conventional ventilation (i.e., set by the carries according to documented guidelines). This is consistent with other articles demonstrating that a sizable number of patients continue to be ventilated using non-recommended settings in spite of clear, evidence-based guidelines.
How to Monitor:
Monitoring the weaning process from mechanical ventilation in SmartCare/PS is crucial. Creating a special page on the ventilator's display that shows graphs representing the weaning diagnosis and the applied pressure support (PS) is ideal. During rounds, physicians can consult this portal to gain an overview of how the weaning process has gone over the last several hours or days. A patient data management system (PDMS) can also receive varied information via SmartCare/PS. On a dedicated weaning page in the PDMS, the entire weaning strategy can be assessed more easily by integrating other relevant factors such as sedation scores, nutrition, and mobility status.
Conclusion:
Closed-loop ventilation is a better way to support patients on breathing machines. It protects the lungs and ensures sufficient oxygen without causing harm. With closed-loop control ventilation, problems like rapid breathing and insufficient air volume are avoided because the ventilation is automatically adjusted based on the patient's breathing. It can be used for any patient throughout their time on the breathing machine, delivering the right amount of air while avoiding excessive lung pressure. Patients with restrictive or obstructive lung conditions should use it since it uses a lung-protective technique. To ascertain its effect on survival for critically sick patients with persistent lung issues, more research is required.
