Background The prone position, frequently used in spine surgeries for optimal surgical access, induces physiological changes in cardiovascular and respiratory parameters. Increased intraabdominal and intrathoracic pressures lead to elevated central venous pressure (CVP). Along with raised intrathoracic pressure, positive end-expiratory pressure (PEEP) results in elevated CVP, impeding venous blood flow from the brain and potentially affecting intracranial pressure (ICP).1 Transcranial Doppler (TCD) ultrasound is a non-invasive method commonly used to measure cerebral hemodynamic parameters, including peak systolic velocity (PSV/ MCAvpeak), mean flow velocity (MFV/MCAvmean), pulsatility index (PI) and resistivity index (RI), which are associated with cerebral vascular resistance, intracranial pressure, and cerebral perfusion pressure (CPP). Method Thirty-three patients undergoing spine surgery were assessed. The vital and TCD parameters PSV/MCAvpeak, MFV/MCAvmean, PI, and RI were noted in the supine position. (Ta). General anaesthesia was administered, and TCD measurements were repeated after induction. (Ts). Patients were then positioned prone, and TCD measurements were repeated at intervals Tp0 - immediately after the prone position, Tp15 -15 min of the prone position, Tp30 -30 min, Tp45 -45 min and Tp60 − 60 min. Vital parameters were noted at the above-mentioned time points. Non-invasive ICP (nICP) was calculated. Results There was a statistically significant decrease in the heart rate (HR) compared to the supine position at Tp45 and Tp45 as compared to Tp0. There was a statistically significant decrease in systolic blood pressure (SBP) as compared to Ta at Tp0 (p < 0.001), Tp15 (p < 0.001), Tp30 (p = 0.003), Tp45 (p = 0.001), and Tp60 (p = 0.018). The study found no statistically significant changes in cerebral hemodynamic parameters (PSV/MCAvpeak, MFV/MCAvmean, PI and RI) and nICP at various time points. Conclusion Our findings suggest that the prone position does not cause significant changes in cerebral hemodynamics and nICP. Trial registration CTRI/2023/06/053677 dated 08/06/2023.

Effect of prone position on cerebral hemodynamics and noninvasive intracranial pressure assessed using transcranial Doppler in patients undergoing spine surgeries: a prospective observational study

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2025年5月15日

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Yaseen Taj,
Navneh Samagh,
Shashank Umesh Paliwal,
Venkata Ganesh,
Ankita Dey,
Varun Aggarwal

摘要

Background

The prone position, frequently used in spine surgeries for optimal surgical access, induces physiological changes in cardiovascular and respiratory parameters. Increased intraabdominal and intrathoracic pressures lead to elevated central venous pressure (CVP). Along with raised intrathoracic pressure, positive end-expiratory pressure (PEEP) results in elevated CVP, impeding venous blood flow from the brain and potentially affecting intracranial pressure (ICP).¹ Transcranial Doppler (TCD) ultrasound is a non-invasive method commonly used to measure cerebral hemodynamic parameters, including peak systolic velocity (PSV/ MCAv_peak), mean flow velocity (MFV/MCAv_mean), pulsatility index (PI) and resistivity index (RI), which are associated with cerebral vascular resistance, intracranial pressure, and cerebral perfusion pressure (CPP).

Method

Thirty-three patients undergoing spine surgery were assessed. The vital and TCD parameters PSV/MCAv_peak, MFV/MCAv_mean, PI, and RI were noted in the supine position. (T_a). General anaesthesia was administered, and TCD measurements were repeated after induction. (T_s). Patients were then positioned prone, and TCD measurements were repeated at intervals T_p0 - immediately after the prone position, T_p15 -15 min of the prone position, T_p30 -30 min, T_p45 -45 min and T_p60 − 60 min. Vital parameters were noted at the above-mentioned time points. Non-invasive ICP (nICP) was calculated.

Results

There was a statistically significant decrease in the heart rate (HR) compared to the supine position at T_p45 and T_p45 as compared to T_p0. There was a statistically significant decrease in systolic blood pressure (SBP) as compared to T_a at T_p0 (p < 0.001), T_p15 (p < 0.001), T_p30 (p = 0.003), T_p45 (p = 0.001), and T_p60 (p = 0.018). The study found no statistically significant changes in cerebral hemodynamic parameters (PSV/MCAv_peak, MFV/MCAv_mean, PI and RI) and nICP at various time points.

Conclusion

Our findings suggest that the prone position does not cause significant changes in cerebral hemodynamics and nICP.

Trial registration

CTRI/2023/06/053677 dated 08/06/2023.