| Model Number 61000 |
| Device Problems
Incorrect Measurement (1383); Incorrect, Inadequate or Imprecise Result or Readings (1535)
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| Patient Problem
Hemoconcentration (1288)
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| Event Date 01/15/2019 |
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Event Type
Injury
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Manufacturer Narrative
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Investigation: device serial number is not available at this time.The article studied rbcx and rbcx with depletion performed between 1 january 2003 and 31 december 2017.17,159 in the final data set.Both children and adults, males and females, are included in this study.Patients who received chronic transfusion therapy are represented multiple times in this dataset.There were 3 groups: male- female group as consisting of patients whose biological sex was male but programmed sex was female.Two comparison groups, female-female and male-male, where biological sex and programmed sex were the same.There were a total of 2433 procedures in the male-female group and 8924 procedures in the control male- male group, and 5802 procedures in the control female-female group.The current study provides empirical validation of the previously theoretically based practice of programming prepubertal males as females to obtain a more accurate estimate of total blood volume and to reduce the chances of hematocrit error in the outcome of automated rce.Even though there are statistical differences between the mean errors of all but two group and subgroup calculations, the absolute magnitudes of the observed differences were not clinically important.We conclude that programming prepubertal boys with the female parameter is safe, and we suggest that a reasonable cutoff weight for beginning to program males with the male parameter is 35 kg.Article citation: colavita d, kim hc, friedman df.The sex parameter in estimation of total blood volume for pediatric erythrocytapheresis.J clin apher.2019;34:692¿699.Https://doi.Org/10.1002/jca.21748 investigation is in process.A follow-up report will be provided.
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Event Description
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The article, "the sex parameter in estimation of total blood volume for pediatric erythrocytapheresis", published in journal of clinical apheresis, suggests that the nadler formula used to estimate total blood volume (tbv) in spectra optia and cobe sepctra may overestimate total blood volume in prepubertal boys (<35 kg weight) undergoing automated red blood cell exchange (rbcx).The publication states (p.693, left column) that the "study was originally prompted by a case in which the measured hematocrit after a rbcx (37%) greatly exceeded the programmed end hematocrit of 30%, requiring a subsequent phlebotomy to reduce the patient's red cell mass.Investigation of this incident led us to believe the deviation of the measured postspun hematocrit from the programmed end hematocrit was a result of a 23% overestimation of the patient's tbv.The patient was a prepubertal male with sickle cell disease who weighed under 35 kg, who had undergone a rbcx on the cobe spectra.Patient identifier, age, weight, and outcome are unknown at this time.
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Manufacturer Narrative
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This report is being filed to provide additional information in h.10.Investigation: as the reported adverse event did not relate to activities associated with the manufacture of an optia device or disposable set, further device history record (dhr) review was not performed for this event.All lots and serial numbers must meet acceptance criteria for release.Investigation is in process.A follow up report will be provided.
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Event Description
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Further patient information and outcome are not available for these events.The disposables set is not available for return because it was discarded by the customer.
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Manufacturer Narrative
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This report is being filed to provide additional information in b.5, e.1, e.3, h.6 and h.10 and corrected information in d.1, d.2 and d.4.Udi# provided in initial mdr report in d.4 is no longer applicable.Investigation: the optia (as well as spectra) is programmed with the nadler formula to estimate tbv.The formula was derived by regression of data from radionuclide based measurements of volumes of distribution in healthy adults.The nadler formula uses three patient parameters: sex, height in meters, and weight in kilograms, as follows: males: tbv= 0.3669 × (ht in m)3 + 0.03219 × wt in kgs +0.6041 females: tbv= 0.3561 × (ht in m)3 + 0.03308 × wt in kgs + 0.1833 the resulting predicted blood volume is measured in liters.The authors hypothesized that the deviation of the measured post spun hematocrit from the programmed end hematocrit in the adverse event which prompted the study was a result of a 23% overestimation of the patient's tbv.The patient was a prepubertal male with scd who weighed under 35 kg, who had undergone a red cell exchange on the cobe spectra.The decision to program procedures for prepubertal males under 35 kg as female was based on modeling of normal growth curve data in nadler's equations.The authors suggested that, when applied to prepubertal males, the nadler formula for males would produce an overestimate of tbv because the equation for males adds a constant value of 0.6041 l, whereas the female equation adds a constant of 0.1833 l.This constant term in the tbv equation, which is the major difference between the male and female versions of the nadler equations, accounts for the greater muscle mass of adult males.However, prepubertal boys, especially those with a chronic illness such as scd, do not generally have as much muscle mass relative to weight and height as healthy adult males.Children with scd also enter puberty 1-2 years later than the average population.The main objective of the study was to determine the difference between the programmed value and the measured value for three specific post procedure outcome measures.The procedures included in the study were both rce and rce with depletion performed on cobe spectra and spectra optia between (b)(6) 2003 and (b)(6) 2017.The male-female group consisted of patients whose biological sex was male, but whose programmed sex was female.The two comparison groups, female-female and male-male, were defined as patients whose biological sex and programmed sex were the same.There were a total of 2433 procedures in the male-female group and 8924 procedures in the control male-male group, and 5802 procedures in the control female-female group.Subcategories by weight (=35 kg vs >35 kg) and by machine type (cobe spectra vs terumo bct spectra optia) were also examined.The practice at the site is to use the ekf diagnostics hemata stat ii from sanford, florida to perform a spun hematocrit (hct) immediately after the completion of a rce.In addition, a post exchange complete blood count (cbc) and hemoglobin (hgb) quantification of hgbs a, s, c, and f percentages is sent to the lab within approximately 30 minutes of the completion of a rce for some but not all procedures.The three error measures in this study were all calculated as programmed or predicted minus measured, as follows: end hematocrit (programmed at start)-post spun hct by hemata stat ii end hematocrit (programmed at start)-post cbc hct predicted post hgb s+c(based on machine predicted fcr)-measured post hgb s+c the findings for the differences between the male-female group and the two controls were consistent with their initial hypothesis, that the male-female programming would result in measured hematocrits that are systematically lower than male-male.Although statistically significant differences in the error measures between the comparison groups were found, the absolute differences observed are clearly quite small and are not significant in clinical transfusion therapy.The small difference, less than 1 hematocrit percentage point in all comparisons, between the measured vs predicted hematocrits in the male-female group supports the safety of programming prepubertal boys as female for the purposes of the nadler estimates of tbv.However, if the male parameter is used for males less than 35 kg, the error in the tbv estimates can be as much as 30%-60%.In the cases where the male parameter was used for boys <35 kg, the mean measured end hct value was greater than the programmed.Stated another way, the mean end hct difference between programming boys <35 kg as female vs as male was observed to be 0.9 hct points higher.If one considered the outlier case of three sds above these means, the measured end hct could be as much as 0.9 + 1.43 × 3 = 5% above the programmed target value.Root cause: the specific root cause of the patient's higher than intended post-procedure hct could not be determined.Possible causes include, but are not limited to, incorrect entry of the replacement fluid hct value (either by data entry or testing/estimation error) and/or overestimation of the patient's tbv based on an inaccurate formula for prepubertal males weighing less than 35kg.
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Manufacturer Narrative
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This report is being filed to provide corrected and additional data in h.10.Investigation: terumo bct medical review determined that the use of the spectra on the small, male patient, referred to in the reference, and operator acceptance of the calculated tbv for the rbcx procedure contributed to the higher than requested post-procedure hematocrit, which resulted in the elevated patient hematocrit requiring medical intervention.Corrected dhr investigation: the disposable lot number was not provided; therefore, a dhr search could not be conducted for this specific incident.All lots must meet acceptance criteria for release.
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Search Alerts/Recalls
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