Journal of Hematology, ISSN 1927-1212 print, 1927-1220 online, Open Access |

Article copyright, the authors; Journal compilation copyright, J Hematol and Elmer Press Inc |

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Case Report

Volume 5, Number 2, June 2016, pages 60-66

**Should the Dose of Recombinant Activated Factor VII Be Adjusted for Morbidly Obese Patients? Balancing Risk of Bleeding With Thrombosis**

Figures

Tables

Method of calculation | Equation | Estimated dose rFVIIa | Comment |
---|---|---|---|

CF: standard pharmacy correction factor; SQRT: square root. | |||

Body mass index (BMI) | kg/m^{2}167 kg weight, 167 cm height BMI = 61 kg/m ^{2} | Considered extreme obesity by NIH guidelines | |

Actual body weight | 167 kg | 90 μg/kg × 167 kg Dose = 15,030 μg | Dose assumes blood volume increases proportionately with actual body weight |

Ideal body weight (IBW) | Females = 45.5 kg + (2.3 kg × every inch > 60) IBW = 57 kg | 90 μg/kg × 57 kg Dose = 5,130 μg | Assumes no increase in blood volume with increase adipose |

Dose based on blood volume [5] | = 70 mL/kg/(SQRT (patient BMI (kg/m^{2})/22)Explanation of variables within equation: Indexed blood volume healthy adults = 70 mL/kg BMI for patient divided by 22 accounts for deviation from IBW | = 70/(SQRT (61/22) = 70/1.665 = 42 mL/kg Standard blood volume estimate by actual weight: = 70 mL/kg × 167 kg = 11,690 mL Indexed blood volume by actual weight: = 42 mL/kg × 167 kg = 7,014 mL Solve for “x” using ratio for indexed dose: (x/7,014 mL) = (15 mg/11,690 mL) x = (15 mg × 7,014 mL)/11,690 mL = 9 mg ( 9,000 μg) | The blood volume corrected for increasing BMI by Lemmens et al [5] formula is 40% lower than the uncorrected empiric estimate of 70 mL/kg used for non-obese adults. This line of reasoning assumes that plasma volume change is equal to blood volume change. |

Adjusted body weight | IBW + (CF (Actual Body Weight - IBW)) 57 + (0.4 (167 - 57)) 57 + 44 = 101 kg | 90 μg/kg × 101 kg Dose = 9,090 μg | Adjusted body weight with a correction factor of 0.4 compares closely with change in blood volume estimation by Lemmens et al [5] |

Hours from SICU admit | Place | rFVIIa dose | Extem measures | Intem measures | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|

A 10 | A 20 | Alpha angle | CFT | CT | MCF | A 10 | A 20 | Alpha angle | CFT | CT | MCF | |||

No range | 50 - 70 | 65-80° | 48 - 127 s | 43 - 82 s | 50 - 70 mm | No range | 51 - 72 | 70-81° | 45 - 110 s | 122 - 208 s | 51 - 72 mm | |||

CFT: clot formation times; CT: clotting time; MCF: maximum clot firmness. | ||||||||||||||

-5.1 | OR | 15 mg | 49 | 57 | 69 | 118 | 97 | 60 | 8 | 13 | 1,420 | |||

-0.5 | OR | 52 | 60 | 73 | 107 | 46 | 62 | 56 | 63 | 62 | 158 | 395 | 65 | |

-0.4 | OR | 57 | 64 | 76 | 88 | 45 | 66 | 8 | 14 | 9 | 1,822 | 1,250 | 26 | |

1.5 | SICU | 49 | 57 | 70 | 115 | 49 | 60 | 60 | 61 | 53 | 61 | 166 | ||

6.7 | SICU | 51 | 59 | 67 | 115 | 72 | 61 | 54 | 61 | 60 | 189 | 526 | 61 | |

10.4 | SICU | 54 | 62 | 71 | 101 | 54 | 63 | 37 | 56 | 42 | 341 | 683 | 64 | |

25.2 | SICU | 9 mg | 51 | 60 | 78 | 105 | 48 | 35 | 40 | 356 | 579 | |||

29.7 | SICU | 50 | 58 | 76 | 97 | 45 | 61 | 23 | 36 | 29 | 504 | 790 | ||

35.9 | SICU | 49 | 58 | 76 | 105 | 41 | 61 | 16 | 25 | 24 | 837 | 842 | 36 | |

42.8 | SICU | 58 | 66 | 78 | 87 | 58 | 69 | 19 | 35 | 25 | 624 | 904 | 52 | |

47.5 | SICU | 58 | 65 | 75 | 92 | 48 | 68 | 24 | 40 | 35 | 487 | 836 | ||

64.3 | SICU | 55 | 62 | 75 | 82 | 50 | 64 | 768 | ||||||

93.5 | SICU | 59 | 65 | 77 | 72 | 71 | 68 | 19 | 33 | 25 | 635 | 793 | ||

115.0 | SICU | 57 | 64 | 74 | 74 | 64 | 67 | 18 | 27 | 38 | 682 | 1,057 | 40 | |

161.3 | SICU | 63 | 68 | 79 | 63 | 52 | 69 | 29 | 43 | 36 | 382 | 642 |