Performance of three new-generation pulse oximeters during motion and low perfusion in volunteers.

STUDY OBJECTIVE: To evaluate pulse oximeter performance during motion and induced low perfusion in volunteers. DESIGN: Prospective volunteer study. SETTING: Direct Observation unit. SUBJECTS: 10 healthy adult volunteers. INTERVENTIONS: Ten volunteers were monitored with three different pulse oximeters while they underwent desaturation to about 75% oxygen saturation (SpO(2)) and performed machine-generated (MG) and volunteer-generated (VG) hand movements with the test hand, keeping the control hand stationary. MEASUREMENTS: SpO(2) and pulse rate readings from the motion (test) and stationary (control) hands were recorded as well as the number of times and the duration that the oximeters connected to the test hands did not report a reading. Sensitivity, specificity, performance index for SpO(2), and pulse rate (PR) were calculated for each pulse oximeter by comparing performance of the test hand with the control hand. MAIN RESULTS: During both MG and VG motion, the Masimo Radical had higher SpO(2) specificity (93% and 97%) than the Nellcor N-600 (67% and 77%) or the Datex-Ohmeda TruSat (83% and 82%). The Masimo Radical also had higher SpO(2) sensitivity (100% and 95%) than the Nellcor N-600 (65% and 50%) or the Datex-Ohmeda TruSat (20% and 15%) during both MG and VG motion. During MG motion, the Masimo Radical had the lowest PR failure rate (0%) compared with the Nellcor N-600 (22.2%) and Datex-Ohmeda TruSat (1.3%). However, during VG motion, the Masimo Radical had the lowest SpO(2) failure rate (0%) of the three devices (Nellcor N-600 16.4% and Datex-Ohmeda TruSat 1.7%). Both the Masimo Radical and the Datex-Ohmeda TruSat had lower PR failure rates (0% and 4.4%) than the Nellcor N-600 (33.9%). There were no significant differences in SpO(2) or PR performance index between the three devices. CONCLUSIONS: The Masimo Radical had higher SpO(2) sensitivity and specificity than the Nellcor N-600 and Datex-Ohmeda TruSat during conditions of motion and induced low perfusion in this volunteer study.

Effect of propofol titration v/s bolus during induction of anesthesia on hemodynamics and bispectral index.

BACKGROUND: Propofol when given as 2 mg/kg IV bolus for induction of anesthesia is known to cause hypotension requiring vasopressors. The objective of our study was to compare Propofol 2 mg/kg single IV bolus (Precalculated group, PG) with the titration of Propofol (Titration group, TG) to clinical parameters as 10 mg IV increments every 3 seconds on hemodynamic Parameters and Bispectral Index (BIS), during induction. The effect of titration on dose requirement for induction was also evaluated. METHODS: Effects on Hemodynamic parameters [Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP)], and vasopressors use were recorded at baseline and every 2 minute intervals for 10 minutes. The percent difference in HR, SBP, DBP, and MAP from baseline at 2, 4, 6, 8 and 10 minutes were calculated, to determine the effect on hemodynamic parameters. BIS was recorded at baseline, after injection of Propofol, at intubation and at 10 minutes. Dose requirement of Propofol in TG was also recorded. RESULTS: At 2 and 4 minutes, SBP decreased in PG by 21% and 18% vs. 11% and 9% in TG (p = .00 & .02); DBP decreased by 17% and 15% in PG vs. 5% and 4% in TG (p = .02 & .03); MAP decreased by 19% and 17% in PG vs. 5% and 4% in TG (p = .00 & .01). Vasopressors were required in 14/43 patients in PG vs. 5/41 in TG (p = .03). Titration resulted in 30% reduction in dose. CONCLUSION: Titration of Propofol reduces hemodynamic changes, dose requirement and is able to achieve same level of BIS as in bolus.