Bedside Breath-Wise Visualization of Bronchospasm by Electrical Impedance Tomography Could Improve Perioperative Patient Safety

Abstract

Bronchospasm appears in up to 4% of patients with obstructive lung disease or respiratory infection undergoing general anesthesia. Clinical examination alone may miss bronchospasm. As a consequence, subsequent (mis)treatment and ventilator settings could lead to pulmonary hyperinflation, hypoxia, hypercapnia, hypotension, patient-ventilator asynchrony, volutrauma, or barotrauma. Electrical impedance tomography (EIT), a new noninvasive technique, can potentially identify bronchospasms by determining regional expiratory time constants (τ) for each one of the pixels of a functional EIT image. We present the first clinical case that highlights the potential of breath-wise EIT-based τ images of the lung to quickly identify bronchospasm at the bedside, which could improve perioperative patient management and safety.

Electrical impedance tomography in perioperative medicine: careful respiratory monitoring for tailored interventions

“…Bronchospasm is another complication of the early post-extubation period, especially in patients with history of asthma, COPD or hyper-reactive airways such as pediatric patients. De la Oliva et al [60] used EIT to monitor changes in global and regional expiratory time constant (τ) in a pediatric patient early after liver transplantation. The authors showed by EIT inhomogeneous distribution of increased τ during bronchospasm with shift of ventilation and air trapping in the ventral lung and rapid decrease of τ and inhomogeneity after suctioning and salbutamol injection.…”

A narrative review of electrical impedance tomography in lung diseases with flow limitation and hyperinflation: methodologies and applications

“…CoV = Σ(y j × ΔZ j )/Σ(ΔZ j ) ×100% [2] where ΔZ j is the image value in pixel j, and y j is the height of pixel j scaled so that the bottom of the image is 0% and the top is 100%. The CoV is an intuitive index that compares the change in ventilation (35), especially when the tidal volume is constant. The CoV is sometimes simplified as the sum of the pixel TV values in the dorsal half of the image as a fraction of the global sum of the pixel TV values in the whole image (37).…”

“…However, while Zhao et al evaluated the ΔZ of the whole tidal breath, the division of the ITVD into the inspiration in several time periods may provide more complex information regarding diaphragm activity ( 65), which may be useful in the assessment of patients with spontaneous breathing. Another measure used to evaluate temporal heterogeneity is the regional time constant, which reflects changes in regional lung mechanics (resistance × compliance) (35,36). The impedance-time curves are fitted using the following equation:…”

Elektrische Impedanztomografie

“…Eine Studie an 14 Frühgeborenen mit sehr geringem Geburtsgewicht bewies die Möglichkeit, den Drucklevel der nichtinvasiven Beatmung nach Extubation mittels EIT zu optimieren [13]. [19].…”