Total hemoglobin (tHb) is one the most frequently ordered laboratory measurements. Pulse CO-Oximetry™ (Masimo Corp., Irvine, CA) is a multi-wavelength spectrophotometric method for noninvasive and continuous hemoglobin monitoring (SpHb). In this study, we evaluated the accuracy of SpHb compared with laboratory CO-Oximeter measurement of tHb from arterial blood samples in 20 healthy volunteer subjects undergoing hemodilution. After enrollment, approximately 500 mL of blood was drawn from subjects through an arterial or venous catheter. Each subject then rapidly received crystalloid i.v. fluid to compensate for the decrease in intravascular volume and reduce the hemoglobin concentration. Subjects received a maximum of 30 mL/kg i.v. fluid. SpHb was continuously monitored and recorded, and serial arterial blood samples were taken during the procedure. SpHb accuracy was analyzed by pairing SpHb and tHb measurements after the arterial blood draw with the resulting tHb test result. Bias, precision, and the average root-mean-square error were calculated. One hundred sixty-five tHb measurements were collected. The average decrease in tHb during the blood removal and hemodilution procedure was 2.4 ± 0.8 g/dL (mean ± SD). The average difference between 335 paired measurements of SpHb and tHb was -0.15 g/dL, 1 SD of the difference was 0.92 g/dL, and the average root-mean-square difference was 0.94 g/dL. The difference between SpHb and tHb was <2.0 g/dL for 97% of the measurements. The difference was <1.5 g/dL for 97% of the measurements when tHb was <10 g/dL. Pulse CO-Oximetry-based SpHb measurement is accurate within 1.0 g/dL (1 SD) compared with laboratory CO-Oximeter tHb measurement in subjects undergoing hemodilution.

This study compared admission rates to a United States anesthesiology residency program for applicants completing face-to-face versus web-based interviews during the admissions process. We also explored factors driving applicants to select each interview type.

Objective: Pre-anesthesia evaluation allows discovery of conditions affecting perioperative planning, but when inadequate it may be associated with delays, cancellations, and preventable adverse events. Not all patients who could benefit will keep appointments. Telemedicine pre-anesthesia evaluation may provide for safe patient care while reducing patient inconvenience and cost. Herein we investigate the impact of telemedicine pre-anesthesia evaluation on perioperative processes. Subjects and Methods: This was a single-center prospective randomized trial in 200 adults scheduled for head and neck surgery at Loma Linda University Medical Center, Loma Linda, CA. Consenting patients not meeting criteria for telephone pre-anesthesia evaluation were randomly assigned to the in-person or telemedicine group. The primary outcome measure was inadequate evaluation caused surgical delay or cancellation. Secondary measures included prediction of difficult airway management and concordance of physical examination. Results: After consent, 40 patients met criteria for telephone screening. Five patients canceled surgery, none for inadequate pre-anesthesia evaluation; thus 155 were randomized. Delay occurred in 1 telemedicine patient awaiting results performed outside our system. Missing documentation at the time of the visit was less common for telemedicine. Difficult airway management was predicted equally but had low positive predictive value. Heart and lung examinations were highly concordant with day of surgery documentation. Patients and providers were highly satisfied with both evaluation modalities. Conclusions: Telemedicine and in-person evaluations were equivalent, with high patient and provider satisfaction. Telemedicine provides potential patient time and cost saving benefits without more day of surgery delay in our system. A prospective trial of patients from multiple surgical specialty clinics is warranted.

BACKGROUND: The use of intraoperative pulse oximetry (Spo ₂) enhances hypoxia detection and is associated with fewer perioperative hypoxic events. However, Spo ₂ may be reported as 98% when arterial partial pressure of oxygen (Pao ₂) is as low as 70 mm Hg. Therefore, Spo ₂ may not provide advance warning of falling arterial oxygenation until Pao ₂ approaches this level. Multiwave pulse co-oximetry can provide a calculated oxygen reserve index (ORI) that may add to information from pulse oximetry when Spo ₂ is >98%. This study evaluates the ORI to Pao ₂ relationship during surgery. METHODS: We studied patients undergoing scheduled surgery in which arterial catheterization and intraoperative arterial blood gas analysis were planned. Data from multiple pulse co-oximetry sensors on each patient were continuously collected and stored on a research computer. Regression analysis was used to compare ORI with Pao ₂ obtained from each arterial blood gas measurement and changes in ORI with changes in Pao ₂ from sequential measurements. Linear mixed-effects regression models for repeated measures were then used to account for within-subject correlation across the repeatedly measured Pao ₂ and ORI and for the unequal time intervals of Pao ₂ determination over elapsed surgical time. Regression plots were inspected for ORI values corresponding to Pao ₂ of 100 and 150 mm Hg. ORI and Pao ₂ were compared using mixed-effects models with a subject-specific random intercept. RESULTS: ORI values and Pao ₂ measurements were obtained from intraoperative data collected from 106 patients. Regression analysis showed that the ORI to Pao ₂ relationship was stronger for Pao ₂ to 240 mm Hg (r ² = 0.536) than for Pao ₂ over 240 mm Hg (r ² = 0.0016). Measured Pao ₂ was ≥100 mm Hg for all ORI over 0.24. Measured Pao ₂ was ≥150 mm Hg in 96.6% of samples when ORI was over 0.55. A random intercept variance component linear mixed-effects model for repeated measures indicated that Pao ₂ was significantly related to ORI (β[95% confidence interval] = 0.002 [0.0019–0.0022]; P < 0.0001). A similar analysis indicated a significant relationship between change in Pao ₂ and change in ORI (β [95% confidence interval] = 0.0044 [0.0040–0.0048]; P < 0.0001). CONCLUSIONS: These findings suggest that ORI >0.24 can distinguish Pao ₂ ≥100 mm Hg when Spo ₂ is over 98%. Similarly, ORI > 0.55 appears to be a threshold to distinguish Pao ₂ ≥150 mm Hg. The usefulness of these values should be evaluated prospectively. Decreases in ORI to near 0.24 may provide advance indication of falling Pao ₂ approaching 100 mm Hg when Spo ₂ is >98%. The clinical utility of interventions based on continuous ORI monitoring should be studied prospectively.