Assessment of short-term blood pressure variability in anesthetized children: A comparative study between intraarterial and finger blood pressure

Objective. Continuous blood pressure (BP) measurement provides instantaneou s information on hemodynamic status, and allows for assessment of sympathet ic modulation of vasomotor tone using spectral analysis. As an alternative to intraarterial blood pressure (IABP) measurement, the Finapres, a photopl ethysmographic device, allows for non-invasive continuous measurement of fi nger blood pressure (FBP). This study was designed to evaluate the accuracy of spectral measurements of FBP variability in children during anesthesia and recovery. For this purpose, reliability of BP measurement and short-ter m BP variability assessed by FBP were calculated and compared with IABP. Me thods. Finger blood pressure was compared with IABP from the ipsilateral ra dial artery, in 14 children undergoing major surgery. Sixty-seven simultane ous recordings of both signals were performed during anesthesia and 32 duri ng recovery period. The accuracy of the FBP was determined by measuring its bias and precision according to the Bland and Altman method. To assess the ability of the FBP to follow short term BP variability, bias of total spec tral power and bias of the 3 main spectral components (LF, MF, HF) were cal culated. Transfer functions between invasive and non-invasive signals were calculated. Results. The average bias of SBP measurement was 3.8 +/- 7.4 mm Hg during anesthesia and 2.2 +/- 6.7 mmHg during recovery. During anesthesi a overall variability and spectral components of FBP and IABP were similar with both techniques; while during recovery, a selective amplification of t he low frequencies (< 0.15 Hz) of FBP was observed. Frequency response anal ysis of the pressure waveform, showed a high coherence between both signal with a gain of 0.96 +/- 0.52 mmHg FBP/mmHg IABP under anesthesia, and of 0. 74 mmHg FBP/mmHg IABP during recovery. Conclusions. The differences evidenc ed between FBP and IABP spectral profiles might result from specific physio logical properties of digital arteries, which are sympathetic effectors. Th is study supports the use of FBP in children to assess non-invasively the v ascular sympathetic component of the autonomic nervous system during anesth esia and recovery.