Hypotensive resuscitation has been advocated as a better means to perform field resuscitation of penetrating trauma. Our hypothesis is that hypotensive resuscitation using either crystalloid or colloid provides equivalent or improved metabolic function while reducing the overall fluid requirement for resuscitation of hemorrhage. We compared hypotensive and normotensive resuscitation of hemorrhage using lactated Ringer's (LR) with hypotensive resuscitation using Hextend (Hex), 6% hetastarch in isotonic buffered saline. Instrumented conscious sheep were hemorrhaged in three separate bleeds, 25 mL/kg at T0 and 5 mL/kg at both T50 and T70. Resuscitation was started at T30 and continued until T180. Hypotensive resuscitation to a mean arterial pressure (MAP) of 65 mmHg was performed with LR or Hex using a closed-loop resuscitation (CLR) system for a LR-65 and Hex-65 treatment protocol. A control treatment protocol was resuscitation with LR to a MAP target of 90 mmHg, LR-90. All treatment protocols were successfully resuscitated to near target levels. Two animals in the hypotensive treatment protocols died during the second and third bleedings, one in the LR-65 and one in the Hex-65 treatment protocol. Mean infused volumes were 61.4 +/- 11.3, 18.0 +/- 5.9, and 11.6 +/- 1.9 mL/kg in the LR-90, LR-65, and Hex-65 treatments, respectively (*P < 0.05 versus LR-90). Mean minimum base excess (BE) values were +1.9 +/- 1.4, -5.8 +/- 4.3, and -5.9 +/- 4.0 mEq/L in the LR-90, LR-65, and Hex-65 treatments, respectively. Hypotensive resuscitation with LR greatly reduced volume requirements as compared with normotensive resuscitation, and Hex achieved additional volume sparing. However, trends toward lower BE values and the occurrence of deaths only in the hypotensive treatment protocols suggest that resuscitation to a target MAP of 65 mmHg may be too low for optimal outcomes.

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A patient often initially presents to an orthopedic surgeon with the magnetic resonance image (MRI) ordered by his or her primary care physician in hand. Often, a significant period of time elapses after injury before the patient is assessed by the orthopedic surgeon; therefore, the initial MRI may be considered outdated because of a new injury or a change in symptoms or because the orthopedist may prefer a new study, a stronger magnet, or a special imaging protocol. However, the decision to repeat a knee MRI is presently an arbitrary one because no clinical guidelines exist to justify this practice.All repeat knee MRIs performed at our academic institution in the past 9 years were retrospectively examined. Inclusion criterion was repeat MRI of the same knee with no surgical intervention. The formal radiology reports were grouped into 3 categories: change, no change, and unclear. Knee pathology was further grouped into 6 categories indicating what specific structures were pathological or injured. Logistic regression analysis was used to test the association of time vs category or condition change between MRIs. Of 3501 knee MRI studies, 88 patients had a total of 101 repeat MRIs. The average number of days between repeats for those with category or condition change was 612 vs 504 for those with no change. Age, sex, and time between MRIs were not significantly associated with a category or condition change. Repeat knee MRI prior to surgical intervention is becoming more prevalent and may have clinical merit. A further prospective study is warranted.

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