TY - JOUR
T1 - Alteration in transthoracic impedance following cardiac surgery
AU - Khan, Nouman
AU - Strang, Tim
AU - Bonsheck, Claire
AU - Bibleraaj, Bhuvaneswari
AU - Hooper, Timothy
PY - 2008/3/25
Y1 - 2008/3/25
N2 - Introduction
Haemodynamically significant ventricular tachyarrhythmias are a frequent complication in the immediate post-operative period after cardiac surgery. Successful cardioversion depends on delivery of sufficient current, which in turn is dependent on transthoracic impedance (TTI). However, it is uncertain if there is a change in TTI immediately following cardiac surgery using cardiopulmonary bypass (CPB).
Methods
TTI was measured on 40 patients undergoing first time isolated cardiac surgery using CPB. TTI was recorded at 30 kHz using Bodystat® Multiscan 5000 equipment before operation (with and without a positive end-expiratory pressure (PEEP) of 5 cm of H2O) and then at 1, 4 and 24 h after the operation. Data was analyzed to determine the relationship between pre- and post-operative variables and TTI values.
Results
Mean pre-operative TTI was 54.5 ± 10.55 Ω without PEEP and 61.8 ± 15.4 Ω on a PEEP of 5 cm of H2O. TTI dropped significantly (p < 0.001) after the operation to 47.2 ± 10.6 Ω at 1 h, 42.6 ± 10.2 Ω at 4 h and 41.8 ± 10.4 Ω at 24 h. A positive correlation was noted between duration of operation and TTI change at 1 h (r = 0.38; p = 0.016). There was no significant correlation between the duration of bypass and change in TTI.
Conclusion
TTI decreases by more than 30% in the immediate post-operative period following cardiac surgery. This state may favour defibrillation at lower energy levels.
AB - Introduction
Haemodynamically significant ventricular tachyarrhythmias are a frequent complication in the immediate post-operative period after cardiac surgery. Successful cardioversion depends on delivery of sufficient current, which in turn is dependent on transthoracic impedance (TTI). However, it is uncertain if there is a change in TTI immediately following cardiac surgery using cardiopulmonary bypass (CPB).
Methods
TTI was measured on 40 patients undergoing first time isolated cardiac surgery using CPB. TTI was recorded at 30 kHz using Bodystat® Multiscan 5000 equipment before operation (with and without a positive end-expiratory pressure (PEEP) of 5 cm of H2O) and then at 1, 4 and 24 h after the operation. Data was analyzed to determine the relationship between pre- and post-operative variables and TTI values.
Results
Mean pre-operative TTI was 54.5 ± 10.55 Ω without PEEP and 61.8 ± 15.4 Ω on a PEEP of 5 cm of H2O. TTI dropped significantly (p < 0.001) after the operation to 47.2 ± 10.6 Ω at 1 h, 42.6 ± 10.2 Ω at 4 h and 41.8 ± 10.4 Ω at 24 h. A positive correlation was noted between duration of operation and TTI change at 1 h (r = 0.38; p = 0.016). There was no significant correlation between the duration of bypass and change in TTI.
Conclusion
TTI decreases by more than 30% in the immediate post-operative period following cardiac surgery. This state may favour defibrillation at lower energy levels.
U2 - 10.1016/j.resuscitation.2008.02.003
DO - 10.1016/j.resuscitation.2008.02.003
M3 - Article (journal)
SN - 0300-9572
VL - 77
SP - 374
EP - 378
JO - Resucitation
JF - Resucitation
IS - 3
ER -