Background: The dorsalis pedis artery (DPA) is a good alternative to the radial artery (RA) for invasive blood pressure monitoring when the upper limb is burned or injured, or if the RA is not available. Understanding the pattern of pressure difference between DPA and the commonly used RA during inhalational anaesthesia is helpful for haemodynamic management and therapeutic decisions.
Objectives: The objective of this study was to investigate the time-dependent variation of DPA-to-RA pressure gradient during sevoflurane anaesthesia and the overall difference between the two pressures during neurosurgery, together with the causes of the pressure gradient change.
Design: A prospective, self-control, single-centre study.
Setting: The operating room of a teaching hospital from 1 January 2013 to 1 September 2013.
Patients: Thirty-seven patients between 18 and 60 years of age, American Society of Anesthesiologists' physical status 1-3, scheduled for neurosurgery in the supine position and requiring invasive arterial pressure monitoring.
Main outcome measures: The time-dependent change of DPA-to-RA pressure gradient and skin temperature gradient, the difference between absolute values and average values of SBP, DBP and mean blood pressure (MBP) between RA and DPA during surgery, and the internal cross-sections and systolic blood flow velocities of RA and DPA at the baseline and at the end of surgery.
Results: Data from 30 patients were analysed. The mean ± standard deviation DPA-to-RA pressure gradient gradually decreased with time from 9.7 ± 8.8 to -1.8 ± 7.6 mmHg for systolic pressure, -2.3 ± 2.7 to -3.7 ± 2.8 mmHg for diastolic pressure and -2.1 ± 3.2 to -5.4 ± 3.4 mmHg for MBP. Biases during the entire procedure were 2.2 ± 10.1, -3.1 ± 3.4 and -4.3 ± 4.2 mmHg for SBP, DBP and MBP, respectively. The DPA-to-RA skin temperature gradient gradually reduced from -3.6 ± 2.4 to -1.1 ± 1.3°C. A greater increase in the inner cross-sectional area and blood flow from the baseline was observed at DPA compared with RA.
Conclusion: The blood pressure, temperature and inner cross-sectional area differences between DPA and RA reduced gradually during sevoflurane anaesthesia in patients undergoing neurosurgery. Therapeutic decisions may rely on DPA pressure as long as the anaesthetists are aware of the pattern of change in DPA pressure during surgery.
Trial registration: www.chictr.org with registry number ChiCTR-RNRC-13003853.