ECHOCARDIOGRAPHIC INSIGHTS OF WEANING FAILURE: PREDICTION & PERSPECTIVES
Journal
Macedonian Journal of Anesthesia
Date Issued
2024-05
Author(s)
Abstract
It has been reported that around 20-30% of mechanically ventilated patients will develop weaning
failure. Since the causes of weaning failure could be diverse, a structured ABCDE approach
was developed in order to deal successfully with such patients. Cardiac dysfunction as a reason
for weaning failure will be discussed in this article, as well as the role of point of care echocardiography
in detection and treatment guidance. Regarding the process of switching patients
from positive pressure ventilation to spontaneous breathing, few cardiopulmonary interactions
occur with potential of failing especially in patients with cardiac and pulmonary comorbidities.
It is well known that in every patient with cardiac dysfunction the level of SvO2 is expected to
be lower than 50%. Systolic disfunction is less frequent cause of weaning failure and could be
diagnosed by simple measurement of MAPSE or LV FAC. On the contrary, diastolic dysfunction
is the leading cause for weaning failure from cardiac origin precipitated by the elevating of
preload and afterload by the spontaneous respiration. Diastolic disfunction could be easily assessed
by measuring the E/A ratio using transmitral PW Doppler and measuring e’ using septal
tissue doppler. Calculation of E/e’ ratio produces a value of Left Atrial Pressure (LAP) which
could be converted in Pulmonary Capillary Wedge Pressure (PCWP) by using the equitation
of Nageh. Measuring a high E wave, low e’ wave and a higher E/e’ ratio were strongly associated
to a diastolic disfunction in a patient that was difficult to wean. Performing echocardiography
before and during a spontaneous breathing trial should be a mainstay for ruling out the weaning
failure risk because of cardiac dysfunction. Higher values for E/e’ showing high left ventricular
filling pressures in patients who are difficult to wean suggest that diastolic dysfunction lies in
the essence of weaning failure.
failure. Since the causes of weaning failure could be diverse, a structured ABCDE approach
was developed in order to deal successfully with such patients. Cardiac dysfunction as a reason
for weaning failure will be discussed in this article, as well as the role of point of care echocardiography
in detection and treatment guidance. Regarding the process of switching patients
from positive pressure ventilation to spontaneous breathing, few cardiopulmonary interactions
occur with potential of failing especially in patients with cardiac and pulmonary comorbidities.
It is well known that in every patient with cardiac dysfunction the level of SvO2 is expected to
be lower than 50%. Systolic disfunction is less frequent cause of weaning failure and could be
diagnosed by simple measurement of MAPSE or LV FAC. On the contrary, diastolic dysfunction
is the leading cause for weaning failure from cardiac origin precipitated by the elevating of
preload and afterload by the spontaneous respiration. Diastolic disfunction could be easily assessed
by measuring the E/A ratio using transmitral PW Doppler and measuring e’ using septal
tissue doppler. Calculation of E/e’ ratio produces a value of Left Atrial Pressure (LAP) which
could be converted in Pulmonary Capillary Wedge Pressure (PCWP) by using the equitation
of Nageh. Measuring a high E wave, low e’ wave and a higher E/e’ ratio were strongly associated
to a diastolic disfunction in a patient that was difficult to wean. Performing echocardiography
before and during a spontaneous breathing trial should be a mainstay for ruling out the weaning
failure risk because of cardiac dysfunction. Higher values for E/e’ showing high left ventricular
filling pressures in patients who are difficult to wean suggest that diastolic dysfunction lies in
the essence of weaning failure.
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