Dan W. Parrish

New low-volume resuscitation solutions containing PEG-20k.

BACKGROUND Hypovolemic shock reduces oxygen delivery and compromises energy-dependent cell volume control. Consequent cell swelling compromises microcirculatory flow, which reduces oxygen exchange further. The importance of this mechanism is highlighted by the effectiveness of cell impermeants in low-volume resuscitation (LVR) solutions in acute studies. The objectives of this study were to assess impermeants in survival models and to compare them with commonly used crystalloid solutions. METHODS Adult rats were hemorrhaged to a pressure of 30 mm Hg to 35 mm Hg, held there until the plasma lactate reached 10 mM, and given an LVR solution (5–10% blood volume) with saline alone (control) and saline with various concentrations of polyethylene glycol-20k (PEG-20k), Hextend, or albumin. When lactate again reached 10 mM following LVR, full resuscitation was started with crystalloid and red blood cells. Rats were either euthanized (acute) or allowed to recover (survival). The LVR time, which is the time from the start of the LVR solution until the start of full resuscitation, was measured as was survival and diagnostic laboratory values. In some studies, the capillary oncotic reflection coefficient was determined for PEG-20k to determine its relative impermeant and oncotic effects. RESULTS PEG-20k (10%) significantly increased LVR times relative to saline (eightfold), Hextend, and albumin. Lower amounts of PEG-20k (5%) were also effective but less so than 10% doses. PEG-20k maintained normal arterial pressure during the low-volume state. Survival of a 180-minute LVR time challenge was 0% in saline controls and 100% in rats given PEG-20k as the LVR solution. Surviving rats had normal laboratory values 24 hours later. PEG-20k had an oncotic reflection coefficient of 0.65, which indicates that the molecule is a hybrid cell impermeant with significant oncotic properties. CONCLUSION PEG-20k–based LVR solutions are highly effective for inducing tolerance to the low-volume state and for improving survival.

Cell Impermeant-based Low-volume Resuscitation in Hemorrhagic Shock: A Biological Basis for Injury Involving Cell Swelling.

Objective:To determine the role of cell swelling in severe hemorrhagic shock and resuscitation injury. Background:Circulatory shock induces the loss of energy-dependent volume control mechanisms. As water enters ischemic cells, they swell, die, and compress nearby vascular structures, which further aggravates ischemia by reducing local microcirculatory flow and oxygenation. Loading the interstitial space with cell impermeant molecules prevents water movement into the cell by passive biophysical osmotic effects, which prevents swelling injury and no-reflow. Methods:Adult rats were hemorrhaged to a pressure of 30 to 35 mm Hg, held there until the plasma lactate reached 10 mM, and given a low-volume resuscitation (LVR) (10%–20% blood volume) with saline or various cell impermeants (sorbitol, raffinose, trehalose, gluconate, and polyethylene glycol-20k (PEG-20k). When lactate again reached 10 mM after LVR, full resuscitation was started with crystalloid and red cells. One hour after full resuscitation, the rats were euthanized. Capillary blood flow was measured by the colored microsphere technique. Results:Impermeants prevented ischemia-induced cell swelling in liver tissue and dramatically improved LVR outcomes in shocked rats. Small cell impermeants and PEG-20k in LVR solutions increased tolerance to the low flow state by two and fivefold, respectively, normalized arterial pressure during LVR, and lowered plasma lactate after full resuscitation, relative to saline. This was accompanied by higher capillary blood flow with cell impermeants. Conclusions:Ischemia-induced lethal cell swelling during hemorrhagic shock is a key mediator of resuscitation injury, which can be prevented by cell impermeants in low-volume resuscitation solutions.

Implementation of pediatric cervical spine clearance guidelines at a combined trauma center: Twelve-month impact.

BACKGROUND Pediatric cervical spine clearance guidelines should reduce computed tomography (CT) usage in combined pediatric and adult trauma centers biased by adult CT clearance. METHODS Cervical spine clearance under age 15 years was compared 12 months before (128 patients) and after (105 patients) guideline implementation, emphasizing National Emergency X-Radiography Utilization Study (NEXUS) criteria when appropriate. RESULTS CT scans in patients clearable by NEXUS criteria decreased 23% (p = 0.01) and decreased by 16% in cases where radiography other than CT was indicated by guidelines (p = 0.01). CONCLUSION Guideline implementation can have an immediate effect in decreasing pediatric cervical spine CT usage and should improve across time. LEVEL OF EVIDENCE Care management study, level IV.

Low-Volume Resuscitation for Hemorrhagic Shock: Understanding the Mechanism of PEG-20k

Hemorrhagic shock leads to cell and tissue swelling and no reflow from compressed capillaries. Cell impermeants, including polyethylene glycol-20,000 (PEG-20k), reverse ischemia-induced cell swelling, extend low-volume resuscitation (LVR) time after shock, and increase tolerance to the low-volume state. The purpose of this study was to explore the mechanisms of action of PEG-20k containing LVR solutions. We hypothesized that PEG-20k acts as both an oncotic agent and an impermeant in the microcirculation, which moves water out of the space and into the capillaries to affect peripheral capillary filling and enhanced perfusion during the low-volume state. Rats were hemorrhaged until arterial lactate reached 9–10 mM/liter. Then, saline-based LVR solutions containing various impermeant materials were administered (10% blood volume). The LVR times for these solutions were determined by measuring the amount of time required for plasma lactate to climb back to 9 to 10 mM after LVR administration (low-volume tolerance). Capillary blood flow was measured by colored microspheres, and blood volume was measured by fluorescein isothiocyanate–labeled albumin dilution. Gluconate (impermeant), albumin (colloid), and PEG-20k (hybrid) increased LVR time over saline by 4-, 3-, and 8-fold, respectively. The combination of impermeant + albumin produced a biologic effect that was similar to PEG-20k alone. Capillary blood flow and plasma volume were decreased after shock with saline LVR but increased with PEG-20k, relative to saline. These data are consistent with the hypothesis that PEG-20k may act by establishing multiple osmotic gradients in the microcirculation to drive cell-to-capillary water transfer during hypovolemic shock.

Laparoscopic gastroesophageal dissociation in neurologically impaired children with gastroesophageal reflux disease

PURPOSE Neurologically impaired children with severe gastroesophageal reflux disease (GERD) are a challenging group of patients. We theorized that a laparoscopic gastroesophageal dissociation (LGED) may decrease reflux-related readmissions and healthcare visits, and improve quality of life (QOL) for them and their caregivers. METHODS A retrospective review was performed on our pediatric patients that underwent an LGED along with a caregiver survey from 2013 to 2017. RESULTS Twenty-two neurologically impaired patients (14months-17years) with severe GERD underwent an LGED. Patients weighed 7.9-57kg (avg=23.8kg), length of stay ranged from 5 to 20days (avg=12days), estimated blood loss ranged from <5cm3 to 450cm3 (avg=66cm3, median=25cm3), and duration of operation ranged from 299 to 641min (avg=462min). One death occurred on postoperative day 19 from gram negative sepsis (30-day perioperative mortality of 4.5%). There were a modest number of minor and major complications (follow-up avg.=13.7months, range=2-40months). There was a decrease in healthcare visits for respiratory illnesses (rated 5/5 from all 13/19 survey respondents) as well as improvements in perceived QOL of the patient (avg=4.3/5) and caregiver (avg=4.6/5). CONCLUSIONS Our cohort of patients had a reduction in readmissions and healthcare visits, and improved QOL after undergoing an LGED based on the perceptions of their caregivers. In neurologically impaired patients with severe GERD, an LGED may be a viable alternative to traditional treatments. TYPE OF STUDY Retrospective case series review. LEVEL OF EVIDENCE Level IV evidence: case series without comparison.

Congenital internal hernias: Rare cause of intestinal obstruction in newborns

Intestinal obstruction in newborns can be life threatening. Congenital internal hernias comprise a very rare cause of the blockage and are thought to arise from a defect in the formation of the mesentery of the small intestine. We describe two cases of neonatal internal hernias and review the current literature. Both infants had clinical signs of obstruction shortly after birth, but the cause of the obstruction was not found until surgical intervention took place. Intestinal necrosis due to segmental twisting of the intestine through a mesenteric defect was found requiring resection and temporary enterostomies. At outpatient follow-up, both children are doing well with normal intestinal function. Our two cases along with the current literature review, illustrate the rare nature of this condition, but one that should be considered in any neonate presenting with intestinal obstruction.