Effect of Cardiorespiratory Changes on Carotid Flow Time During Lung Resection Surgery

Longitudinal study

Repeated measurements design

Change in corrected carotid artery flow (ccFT) in association with cardiorespiratory changes and volume expansion during lung resection surgery

Doppler ultrasonography measurements are performed repeatedly at following timepoints: awake (seated), awake (supine), after intubation, after lateral decubitus position, after transition to one-lung ventilation, after pleura opening, after carbon dioxide insufflation, before lung recruitment, after first highest PEEP, after second highest PEEP, after optimal PEEP, before and after volume expansion.

Statistical analysis: within-patient change (Friedman, Wilcoxon signed rank), correlation

Diagnostic accuracy of corrected carotid flow time (ccFT) and recruitment - induced change in carotid corrected flow time (delta ccFTRM) in discriminating fluid responders during one-lung ventilation

Corrected carotid flow time (ccFT) is measured by Doppler ultrasonography immediately before volume expansion (VE) and 5 min after it.

Recruitment - induced change in carotid corrected flow time (delta cFTRM) is calculated from measurments obtained by Doppler utrasonography immediately before recruitment maneuver (RM) and at highest PEEP.

delta ccFTRM = (ccFT before RM - ccFTafter RM) / ccFT before RM

Fluid response is defined as > 15% increase in cardiac output (CO) following volume expansion (VE). Volume expansion is a 200-250 ml bolus of crystalloid solution performed after the recruitment maneuver (RM) at the discretion of attending anesthesiologist. Measurements are obtained by pulse contour analysis after immediately before volume expansion (VE) and 5 min after it.

Stat- ROC curve

Outcome measure - prognostic ability (AUC)of corrected carotid flow time (ccFT) and recruitment - induced change in carotid corrected flow time (delta ccFTRM) in predicting CO increase.

Diagnostic accuracy of baseline preoperative carotid flow time (ccFT) in discriminating between poor and good tolerance to recruitment maneuver and preoperative position-induced change in ccFT in discriminating fluid responders and non-responders.

Baseline preoperative carotid corrected flow time (ccFT) is a preoperative carotid Doppler measurement in seated position.

Position-induced change (delta ccFT-P) is calculated from measurments obtained by Doppler utrasonography in awake seated position and within approxiamtely 10-15 minutes in awake supine position.

delta ccFTP = (ccFT awake seated - ccFTawake supine ) / ccFT awake seated

Poor tolerance to lung recruitment is defined as TWA-MAP of 20% decrease from baseline or absolute value < 65 mmHg measured during recruitment period or 10 min after. Measurements are obtained by pulse contour analysis from immediately before recruitment maneuver to 5 min after it.

Fluid response is defined as > 15% increase in cardiac output (CO) following volume expansion (VE). Volume expansion(VE) is a 200-250 ml bolus of crystalloid solution performed after the recruitment maneuver (RM) at discretion of attending anesthesiologist.

Change in cerebral blood volume index (CBVIl, CBVIr) in association with cardiorespiratory changes and volume expansion during lung resection surgery

Doppler ultrasonography measurements are performed repeatedly at following timepoints: awake (seated), awake (supine), after intubation, after lateral decubitus position, after transition to one-lung ventilation, after pleura opening, after carbon dioxide insufflation, before lung recruitment, after first highest PEEP, after second highest PEEP, after optimal PEEP, before and after volume expansion.

Statistical analysis: within-patient change (Friedman, Wilcoxon signed rank), correlation (with cardiac output)

Change in secondary hemodynamic and ventilatory variables in response to cardiorespiratory changes and volume expansion during lung resection surgery

Hemodynamic variables (CO, SV, MAP, HR, dP/dt, Eadyn, PI, BIS, carotid diameter, resistivity index) are obtained from pulse contour analysis/ Doppler and respiratory variables (EtCO2, Ppeak, PEEP, TV, SpO2, FiO2, RR) are obtained from mechanical ventilator continuously during the same timepoints as primary variable.

Outcome measure: all variables will be taken and reported at the following timepoints: awake (seated), awake (supine), after intubation, after lateral decubitus position, after transition to one-lung ventilation, after pleura opening, after carbon dioxide insufflation, before lung recruitment, after first highest PEEP, after second highest PEEP, after optimal PEEP, before and after volume expansion.

Statistical analysis: within-patient change (Friedman, Wilcoxon signed rank), correlation

Comparative between-group analysis of primary and secondary variables in patients of different sex, ventilation protocol, operative side, recruitment tolerance and fluid response.

Hemodynamic (CO, SV, MAP, HR, dP/dt, Eadyn, PI, BIS, carotid diameter, resistivity index) are obtained from pulse contour analysis/ Doppler and respiratory variables (EtCO2, Ppeak, PEEP, TV, SpO2, FiO2, RR) will be collected at following timepoints: awake (seated), awake (supine), after intubation, after lateral decubitus position, after transition to one-lung ventilation, after pleura opening, after carbon dioxide insufflation, before lung recruitment, after first highest PEEP, after second highest PEEP, after optimal PEEP, before and after volume expansion. Comparative between-group analysis of variables response will be performed. Groups are stratified by sex, ventilation protocol, operative side, recruitment tolerance and fluid response. Statistical analysis: between-patient change (Mann-Whitney).