Impact of Transfusing Packed Red Blood Cells Through a Rapid Infuser on Potassium Levels.

BACKGROUND: Hyperkalemia is associated with the rapid transfusion of packed red blood cells in trauma patients. Rapid infusers can infuse blood up to 500 ml/min. OBJECTIVE: This study aimed to determine whether infusing packed red blood cells through a rapid infuser impacts the potassium levels of the infused blood. METHODS: Two baseline samples were obtained to measure potassium and hemolysis scores in 12 units of expired blood prior to infusion. The blood was then infused via the Belmont Rapid Infuser into collection bags at varying infusion rates (50, 100, 250, and 500 ml/min) utilizing different gauge catheter sizes (18-gauge, 16-gauge, and Cordis catheter). Two postinfusion blood samples were collected and tested for potassium and hemolysis scores and compared with preinfusion values. This process was then repeated with fresh blood. RESULTS: The potassium levels of the samples taken from each unit prior to infusion (average difference 0.245) and after infusion (average difference 0.08) correlated well. There was no difference in potassium levels pre- and postinfusion at any infusion rate after accounting for catheter size and age of blood. The median potassium level of the fresh blood was 5.025 prior to infusion and 4.875 after infusion. The median potassium level of the expired blood was 16.05 prior to infusion and 16.4 postinfusion. There was no significant difference in the hemolysis scores between the preinfusion and postinfusion samples. CONCLUSIONS: Hyperkalemia in trauma patients undergoing massive transfusions is not a result of mechanical hemolysis from the high rates of blood infusion.

Ketamine in pain management.

Ketamine is an N-methyl-D-aspartate receptor antagonist that has been in clinical use in the USA for over 30 years. Its ability to provide profound analgesia and amnesia while maintaining spontaneous respiration makes it an ideal medication for procedure-related pain and trauma. In the chronic pain arena, its use continues to evolve. There is strong evidence to support its short-term use for neuropathic and nociceptive pain, and conflicting evidence for preemptive analgesia. Its potential ability to prevent 'windup' and, possibly, 'reboot' aberrant neurologic pathways in neuropathic and central pain states has generated intense interest. However, the long-term use of ketamine for chronic neuropathic pain is limited by its side effect profile, and is largely anecdotal. More research is needed to better ascertain its long-term efficacy and side effects, to determine the ideal candidates for sustained treatment and to develop means of exploiting the antinociceptive properties of ketamine while minimizing the adverse effects.

A prospective evaluation of the value of repeat cranial computed tomography in patients with minimal head injury and an intracranial bleed.

BACKGROUND: Patients with minimal head injury (MHI) and intracranial bleed (ICB) detected on cranial computed tomography (CT) scan routinely undergo a repeat cranial CT within 24 hours after injury to assess for progression of intracranial injuries. While this is clearly beneficial in patients with a deteriorating neurologic status, it is of questionable value in patients with a normal neurologic examination. The goal of this study was to prospectively assess the value of a repeat cranial CT in patients with a MHI and an ICB who have a normal neurologic examination. METHODS: A prospective analysis of all adult patients admitted to a Level I trauma center after blunt trauma causing a MHI (defined as the loss of consciousness or posttraumatic amnesia with a Glasgow Coma Scale (GCS) score of greater or equal to 13) and an ICB on the initial cranial CT during a 12-month period (July 2002 through July 2003) was performed. All patients with MHI were prospectively evaluated and followed until discharge. Data collected included demographics, neurologic examination and findings on the initial and repeat cranial CT scan. Outcome data included neurologic deterioration, neurosurgical intervention, and Glasgow Outcome Scale (GOS) on discharge. RESULTS: In all, 161 consecutive patients with MHI and a positive cranial CT scan were identified. The initial cranial CT lead to a neurosurgical intervention (1 craniotomy, 4 intracranial pressure monitors) in 4% of cases. The remaining 130 patients who met inclusion criteria, underwent a repeat cranial CT scan within 24 hours postadmission. Ninety nine (76%) patients had a normal neurologic examination at the time of their repeat cranial CT. After the repeat cranial CT none required immediate neurosurgical intervention or had delayed neurologic deterioration related to their head injury. Fifteen patients underwent additional neuroradiologic studies but none showed further progression of their ICB or lead to a change in management. One patient died from non-traumatic brain injury related causes and of the remaining 26 patients, 98% had an overall favorable GOS score (> 3) on discharge. In this group of patients with MHI and ICB, the negative predictive value of a normal neurologic examination was 100%. CONCLUSIONS: Repeat cranial CT, in patients with a MHI and a normal neurologic examination, resulted in no change in management or neurosurgical intervention and is therefore not indicated. A multicenter prospective study would further validate these conclusions, reduce unnecessary CT scans, and likely improve our current standard of care in these patients.