PATIENT-VENTILATOR ASYNCHRONY, HOW TO DETECT AND HOW TO MANAGE ?
Mohammed Kamar Aldawla Mohammed Abozeda;
Abstract
The respiratory system is both remarkable and complicated. Knowledge of pulmonary anatomy provides a sound foundation for understanding the complex processes of respiration ( Pierce, 2006).
Over the past decades, the respiratoryphysiology research has greatly improved our understanding of the respiratory sys-tem.Successful mechanical ventilation requires a basic understanding of respiratory physiology and ventilator mechanics (Davenport et al.,2010).
Mechanical ventilation is a commonly used technique in the intensive care unit(ICU)(Slutsky and Brochard, 2006).
Many factors affect the decision to begin mechanical ventilation. Because no mode of mechanical ventilation can cure a disease process, the patient should have a correctable underlying problem that can be resolved with the support of mechanical ventilation. This intervention should not be started without thoughtful consideration because intubation and positive-pressure ventilation are not without potentially harmful effects. Mechanical ventilation is indicated when the patient's spontaneous ventilation is inadequate to sustain life ( Byrdet al., 2013).
The evidence base for the use of non-invasive ventilation (NIV) in anumber of different clinical situations has increased greatly in recent years; however, there remain a number of contraindications to its use. despite increasing interest in its use, NIV should not be considered as a replacement for MV and should not delay intubation and MV in those patients who fail to respond to or deteriorate on NIV (McNeill and Glossop, 2012).
Patient-ventilator asynchrony, defined as a mismatch between the patient’s neural inspiratory time and the ventilator’s insufflation time (Thille et al., 2008).
Given the multiple interactions between the patient’s innate control of breathing and ventilator operation, it is not surprising that patient-ventilator synchrony is more often the exception than the rule (Branson, 2011).
The goal of patient-ventilator synchrony is to have the various parts of ventilator-assisted breathing coincide with the patient’s intrinsic breathing pattern (De Wit, 2011).
Patient-ventilator interaction is influenced by factors related to the patient and factors related to the ventilator. Patient-related factors such as respiratorycenter output, respiratory mechanics, disease states or conditions and endotracheal tube type or size influence the patient-ventilator interaction (Mellott et al., 2009).
Synchronous patient-ventilator interaction requires a ventilator to be sensitive to respiratory efforts and responsive to airflow demand. Two major factors contributing to PVD are ventilator triggering (signal opens inspiratory valve) and cycling (signal opens expiratory valve at end inspiration) (Racca et al., 2005).
Patient-ventilator asynchrony is common, and its prevalence depends on numerous factors, including timing and duration of observation; detection technique; patient population; type of asynchrony; ventilation mode and settings (eg, trigger, flow, and cycle criteria); and confounding factors (eg, state of wakefulness, sedation) (Epstein, 2011 ).
Monitoring of patient-ventilator interactions at the bedside is an integral part of caring for the critically ill patient. Caring for the mechanically ventilated patient involves examining the impact of patient breathing and behavior on ventilator settings, and vice versa (MacIntyre and Branson, 2009).
Accurate assessment of patient-ventilator interactions and work of breathing (WOB) requires invasive measurements of pleural pressure and/or respiratory muscle electromyogram. Use of an esophageal balloon, which permits determination of pleural pressure, and respiratory muscle electromyograms have been used to measure a variety of patient-ventilator interactions and to compute WOB. However, these devices are not used during routine patient care and clinicians must rely on physical examination of the patient as well as visual inspection of waveforms to assess for patient-ventilator synchrony and asynchrony. Visual inspection of waveforms has been shown to correlate well with esophageal-balloon readings, but is not without error (Spahija et al., 2010).
It is important for clinicians not to assume that ventilator settings are optimal for the patient. Rather, clinicians must evaluate the patient and response to ventilator settings before drawing conclusions about patient-ventilator synchrony. The patient is the focus point and the clinician must adjust the mechanical ventilator to meet the patient’s ventilatory requirements. The goal is to have the “right tool for the right job,” and clinicians must not assume that one “tool” (ie, set of ventilator parameters) satisfies the needs of different patients. It is only after careful observation of the patient and examination of ventilator waveforms that clinicians should assume the patient and ventilator are synchronous. When a patient appears uncomfortable, physical examination and evaluation of ventilator waveforms are the first steps in the management of the patient (de Wit, 2011).
Over the past decades, the respiratoryphysiology research has greatly improved our understanding of the respiratory sys-tem.Successful mechanical ventilation requires a basic understanding of respiratory physiology and ventilator mechanics (Davenport et al.,2010).
Mechanical ventilation is a commonly used technique in the intensive care unit(ICU)(Slutsky and Brochard, 2006).
Many factors affect the decision to begin mechanical ventilation. Because no mode of mechanical ventilation can cure a disease process, the patient should have a correctable underlying problem that can be resolved with the support of mechanical ventilation. This intervention should not be started without thoughtful consideration because intubation and positive-pressure ventilation are not without potentially harmful effects. Mechanical ventilation is indicated when the patient's spontaneous ventilation is inadequate to sustain life ( Byrdet al., 2013).
The evidence base for the use of non-invasive ventilation (NIV) in anumber of different clinical situations has increased greatly in recent years; however, there remain a number of contraindications to its use. despite increasing interest in its use, NIV should not be considered as a replacement for MV and should not delay intubation and MV in those patients who fail to respond to or deteriorate on NIV (McNeill and Glossop, 2012).
Patient-ventilator asynchrony, defined as a mismatch between the patient’s neural inspiratory time and the ventilator’s insufflation time (Thille et al., 2008).
Given the multiple interactions between the patient’s innate control of breathing and ventilator operation, it is not surprising that patient-ventilator synchrony is more often the exception than the rule (Branson, 2011).
The goal of patient-ventilator synchrony is to have the various parts of ventilator-assisted breathing coincide with the patient’s intrinsic breathing pattern (De Wit, 2011).
Patient-ventilator interaction is influenced by factors related to the patient and factors related to the ventilator. Patient-related factors such as respiratorycenter output, respiratory mechanics, disease states or conditions and endotracheal tube type or size influence the patient-ventilator interaction (Mellott et al., 2009).
Synchronous patient-ventilator interaction requires a ventilator to be sensitive to respiratory efforts and responsive to airflow demand. Two major factors contributing to PVD are ventilator triggering (signal opens inspiratory valve) and cycling (signal opens expiratory valve at end inspiration) (Racca et al., 2005).
Patient-ventilator asynchrony is common, and its prevalence depends on numerous factors, including timing and duration of observation; detection technique; patient population; type of asynchrony; ventilation mode and settings (eg, trigger, flow, and cycle criteria); and confounding factors (eg, state of wakefulness, sedation) (Epstein, 2011 ).
Monitoring of patient-ventilator interactions at the bedside is an integral part of caring for the critically ill patient. Caring for the mechanically ventilated patient involves examining the impact of patient breathing and behavior on ventilator settings, and vice versa (MacIntyre and Branson, 2009).
Accurate assessment of patient-ventilator interactions and work of breathing (WOB) requires invasive measurements of pleural pressure and/or respiratory muscle electromyogram. Use of an esophageal balloon, which permits determination of pleural pressure, and respiratory muscle electromyograms have been used to measure a variety of patient-ventilator interactions and to compute WOB. However, these devices are not used during routine patient care and clinicians must rely on physical examination of the patient as well as visual inspection of waveforms to assess for patient-ventilator synchrony and asynchrony. Visual inspection of waveforms has been shown to correlate well with esophageal-balloon readings, but is not without error (Spahija et al., 2010).
It is important for clinicians not to assume that ventilator settings are optimal for the patient. Rather, clinicians must evaluate the patient and response to ventilator settings before drawing conclusions about patient-ventilator synchrony. The patient is the focus point and the clinician must adjust the mechanical ventilator to meet the patient’s ventilatory requirements. The goal is to have the “right tool for the right job,” and clinicians must not assume that one “tool” (ie, set of ventilator parameters) satisfies the needs of different patients. It is only after careful observation of the patient and examination of ventilator waveforms that clinicians should assume the patient and ventilator are synchronous. When a patient appears uncomfortable, physical examination and evaluation of ventilator waveforms are the first steps in the management of the patient (de Wit, 2011).
Other data
| Title | PATIENT-VENTILATOR ASYNCHRONY, HOW TO DETECT AND HOW TO MANAGE ? | Other Titles | كيفية إدارة وإكتشاف اللا توافق بين المريض وجهاز التنفس الصناعي | Authors | Mohammed Kamar Aldawla Mohammed Abozeda | Issue Date | 2014 |
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