Continuous noninvasive hemoglobin monitoring estimates timing for detecting anemia better than clinicians: A randomized controlled trial

Abstract

Background Hemoglobin measurement is important for transfusion decision-making. Pulse CO-Oximetry provides real-time continuous hemoglobin (SpHb) monitoring. The triage role of SpHb trends based on hemoglobin measurements was investigated. Methods In this diagnostic randomized controlled trial, 69 patients undergoing spine or cytoreductive surgery were randomly enrolled into SpHb-monitoring and standard-care groups. Diagnostic blood samples were drawn for CO-oximetry Hb (CoOxHb) when the SpHb decreased by 1 g/dl or at the clinician’s discretion in the standard-care group. The positive predictive value (PPV) was defined as the ability to detect a decrease in CoOxHb > 1 g/dl or a CoOxHb < 10 g/dl; the PPVs were compared using Fisher’s exact test. The SpHb and trend accuracies were calculated. The transfusion units and postoperative hemoglobin levels were compared. Results The PPV of a decrease in CoOxHb > 1 g/dl was 93.3% in the SpHb group vs 54.5% without SpHb monitoring (p = 0.002). The PPV of CoOxHb < 10 g/dl was 86.7% vs. 50.0% for these groups (p = 0.015). The CoOxHb was never < 7 g/dl with SpHb monitoring. Sixty SpHb–CoOxHb data pairs and 28 delta pairs (ΔSpHb-ΔCoOxHb) were collected. The bias, precision and limits of agreement were -0.29, 1.03 and -2.30 to 1.72 g/dl, respectively. When ΔSpHb and ΔCoOxHb were > 1 g/dl, the concordance rate for changes in hemoglobin reached 100%. The delta pairs revealed a positive correlation [ΔSpHb = 0.49 * ΔCoOxHb - 0.13; r = 0.69, 95% confidence interval (0.53, 0.82)]. No significant differences were found in the transfusion volume or postoperative anemia state. Conclusions The SpHb trend tracked changes in hemoglobin satisfactorily during surgery and more accurately estimated the appropriate timing for invasive hemoglobin measurements than the clinicians. Trial Registration ChiCTR1800016290, Date of registration 24 May 2018.

Multicenter comparison of three intraoperative hemoglobin trend monitoring methods

“…When using the exclusion zones determined by measurement repeatability analysis but not excluding SpHb based on low perfusion index, SpHb concordance was 94.2%. Our findings are also better than reported in 69 patients undergoing spine or cancer surgery that employed a 1 g/dl exclusion zone [ 20 ]. A study of patients undergoing abdominal or pelvic surgery found 41 of 269 changes at any Hb had increased SpHb when ABGHb decreased, including 14 in which the decrease was more than − 1 g/dl [ 11 ].…”

The usefulness of non‐invasive co‐oximetry haemoglobin measurement for screening pre‐operative anaemia

“…Tang et al compared the PPV of a SpHb drop with clinical judgement in predicting a haemoglobin drop of > 1.0 g.dl À1 in patients undergoing spine surgery using the Radical-7 â Pulse Co-Oximeter. The PPV was 0.93 in the SpHb group and 0.55 in the non-SpHb group[9]. They also found the PPV to be 0.87 for LabHb < 10.0 g.dl À1 detection with SpHb, whereas our patient sample had a PPV of 0.72 for LabHb < 13.0 g.dl À1 .…”

“…Accuracy studies in different clinical settings for its predecessors reached conflicting conclusions [4][5][6][7][8][9]. A previous study evaluating the ability of non-invasive oximetry haemoglobin (SpHb) in detecting pre-operative anaemia using an older version (Pronto-7 with Rainbow 4D TM sensor (Pronto-7)) found they were unable to obtain stable readings in 20% of patients and had a reduced accuracy in women [10].…”

“…The non‐invasive spectrophotometry‐based device, Rad‐67™ Spot‐check Pulse Co‐Oximeter ® with Rainbow ® Super DCI ® ‐mini Sensor technology (Masimo Corp., Irvine, CA, USA) (Rad‐67™ Rainbow), was introduced in 2019. Accuracy studies in different clinical settings for its predecessors reached conflicting conclusions [4–9]. A previous study evaluating the ability of non‐invasive oximetry haemoglobin (SpHb) in detecting pre‐operative anaemia using an older version (Pronto‐7 with Rainbow 4D™ sensor (Pronto‐7)) found they were unable to obtain stable readings in 20% of patients and had a reduced accuracy in women [10].…”