Fat Intravasation from Intraosseous Flush and Infusion Procedures

Intra-osseous cerebrospinal fluid shunts-Overview of past and present clinical and experimental evidence

In the history of hydrocephalus treatment, a variety of diversion sites have been explored to ensure an adequate alternative when the peritoneum was not a feasible option. An interesting choice was the elimination of excessive cerebrospinal fluid (CSF) in the skeletal system. The purpose of this review was to evaluate all shunting systems that have been implemented in bone structures and to determine their therapeutic potential. All articles pertaining to bone derivations were selected from PubMed, Medline, EBSCO and Scopus, using relevant search terms. The search revealed 6 types of osseous shunts that have been used throughout history: vertebral, diploic, ventriculomastoid, ventriculoiliac, ventriculosternal and ventriculohumeral. Some of them are purely of historical significance, but data from more recent clinical and experimental studies have rendered this type of receptacle a potential site for diverting CSF. Having knowledge of all the alternatives used in cases of refractory hydrocephalus is vital for choosing the appropriate surgical intervention.

Fat embolism after intraosseous catheters in pediatric forensic autopsies

In our center, we performed the autopsy of a child who died from drowning and presented, at autopsy, a major pulmonary fat embolism (PFE). A cardiopulmonary resuscitation (CPR) was performed, including infusion by intraosseous catheter (IIC). No other traumatic lesions and diseases classically related to a risk of PFE were detected. According to some animal studies, we considered the IIC as the only possible cause for PFE. However, we could not find literature to confirm this hypothesis in humans, especially in a pediatric population. To verify the occurrence of PFE after IIC in a pediatric population, we retrospectively selected 20 cases of pediatric deaths autopsied in our center, in which a CPR was performed, without bone fractures or other possible causes of PFE: 13 cases with IIC (group A) and 7 cases without IIC (group B). Several exclusion criteria were considered. The histology slides of the pulmonary tissue were stained by Oil Red O. PFE was classified according to the Falzi scoring system. In group A, 8 cases showed PFE: 4 cases with a score 1 of Falzi and 4 cases with a score 2 of Falzi. In group B, no case showed PFE. The difference between the two groups was statistically significant. The results of our study seem to confirm that IIC can lead to PFE in a pediatric population and show that the PFE after IIC can be important (up to score 2 of Falzi). To the best of our knowledge, our study is the first specifically focused on the occurrence of PFE after IIC in a pediatric population by using autoptic data.

Intraosseous fluid resuscitation causes systemic fat emboli in a porcine hemorrhagic shock model

BACKGROUND

Intraosseous cannulation can be life-saving when intravenous access cannot be readily achieved. However, it has been shown that the procedure may cause fat emboli to the lungs and brain. Fat embolization may cause serious respiratory failure and fat embolism syndrome. We investigated whether intraosseous fluid resuscitation in pigs in hemorrhagic shock caused pulmonary or systemic embolization to the heart, brain, or kidneys and if this was enhanced by open chest conditions.

METHODS

We induced hemorrhagic shock in anesthetized pigs followed by fluid-resuscitation through bilaterally placed tibial (hind leg) intraosseous cannulas. The fluid-resuscitation was limited to intraosseous or i.v. fluid therapy, and did not involve cardiopulmonary resuscitation or other interventions. A subgroup underwent median sternotomy with pericardiectomy and pleurotomy before hemorrhagic shock was induced. We used invasive hemodynamic and respiratory monitoring including Swan Ganz pulmonary artery catheter and transesophageal echocardiography and obtained biopsies from the lungs, heart, brain, and left kidney postmortem.

RESULTS

All pigs exposed to intraosseous infusion had pulmonary fat emboli in postmortem biopsies. Additionally, seven of twenty-one pigs had coronary fat emboli. None of the pigs with open chest had fat emboli in postmortem lung, heart, or kidney biopsies. During intraosseous fluid-resuscitation, three pigs developed significant ST-elevations on ECG; all of these animals had coronary fat emboli on postmortem biopsies.

CONCLUSIONS

Systemic fat embolism occurred in the form of coronary fat emboli in a third of the animals who underwent intraosseous fluid resuscitation. Open chest conditions did not increase the incidence of systemic fat embolization.

Single Versus Double Anatomic Site Intraosseous Blood Transfusion in a Swine Model of Hemorrhagic Shock

BACKGROUND

Blood transfusion via single site intraosseous access is a critical modality when caring for a trauma victim that lacks intravascular access. Flow rates and potential clinical complications when utilizing two sites of intraosseous access are not well known.

MATERIALS AND METHODS

Anesthetized adult female Yorkshire swine (Sus scrofa; n = 48; 76.7 ± 1.75kg; range 66-90kg) were cannulated and then bled approximately 30% total blood volume. Swine were randomly assigned to treatment groups: single sited humerus, single sited sternum, dual sited humerus or dual sited humerus and sternum. Flow rates, hemolysis, physiologic measurements, biochemical variables, and pulmonary histologic inflammation and occlusion were contrasted between groups.

RESULTS

Dual sited intraosseous transfusion flow rates (128ml/min, 95% CI 123-132) were double the flow rates of single sites (65ml/min, 95% CI 60-70), P < .0001.Single sited humeral flow rates were greater than sternal flow rates, with respective averages of 74ml/min and 55ml/min, though not reaching statistical significance (P < 0.17). There was no significant elevation of plasma free hemoglobin in any group after transfusion as compared to baseline (P = 0.7). Groups did not significantly differ in vitals or biochemical variables. Most pulmonary specimens had some intraparenchymal fat embolism, however no animals had evidence of occlusive intra-arterial fat embolism.

CONCLUSIONS

Dual anatomic site, pressure bag driven, intraosseous blood transfusion approximately doubles flow rates without evidence of clinical complications or hemolysis. Further research using a survivability model is needed to characterize long-term complications from pressurized IO transfusions.

Safety of Pressurized Intraosseous Blood Infusion Strategies in a Swine Model of Hemorrhagic Shock

BACKGROUND

Current guidelines support intraosseous access for trauma resuscitation when intravenous access is not readily available. However, safety of intraosseous blood transfusions with varying degrees of infusion pressure has not been previously characterized.

MATERIALS AND METHODS

Adult female Yorkshire swine (Sus scrofa; n = 36; mean (M): 80 kg, 95% CI: 78-82 kg) were cannulated and then bled approximately 30% total blood volume. Swine were randomly assigned to proximal humerus intraosseous blood infusion with either Rapid Infuser, or Pressure Bag, or Push-Pull methods (n = 12 each). Flow rates, infusion pressures, vitals, biochemical variables, and pulmonary and renal tissue pathology were contrasted between groups.

RESULTS

Flow rates were greater for the Push-Pull strategy than Pressure Bag (96.5 mL/min versus 72.6 mL/min, P = 0.02) or Rapid Infuser (96.5 mL/min versus 60 mL/min, P = 0.002) strategies. The pressures generated during the Push-Pull transfusion (3058 mmHg) were greater than the other strategies (≤360 mmHg). After the observation period, plasma-free hemoglobin levels were higher in the Push-Pull strategy than in the Rapid Infuser (40 mg/dL versus 12 mg/dL, P = 0.02) or Pressure Bag (40 mg/dL versus 12 mg/dL, P = 0.01). Groups did not significantly differ in vitals, biochemical variables, or tissue pathology.

CONCLUSIONS

Push-Pull conferred the highest flow rates, but with higher infusion pressures and evidence of intravascular hemolysis. Rapid Infuser and Pressure Bag infusions had no increase from baseline in plasma-free hemoglobin. Pressure Bag infusion was noted to confer an advantage in flow rates over Rapid Infuser. Intraosseous blood transfusion with pressure bags can safely bridge toward central access in the early phases of trauma resuscitation.

Neurologic Complications of Fat Embolism Syndrome

PURPOSE OF REVIEW

Fat embolism syndrome (FES) is a rare disorder with potentially devastating neurologic complications. This article reviews the history, pathophysiology, clinical features, diagnosis, and treatment of FES with a focus on its neurologic aspects.

RECENT FINDINGS

The neurologic complications of FES are more commonly recognized with current diagnostic testing and increase awareness of the disorder. FES may present initially with neurologic manifestations. Prompt diagnosis of FES and of its neurologic manifestations could be lifesaving. This includes respiratory support and management of neurological complications. The classic clinical triad of pulmonary insufficiency, neurologic disturbances, and petechial skin rash typically presents 24 to 72 h following an initial insult, most commonly a traumatic long bone fracture. Early onset (< 24 h) and delayed onset (> 72 h) have been described. Neurologic manifestations may include ischemic/hemorrhagic strokes, retinal ischemia, seizures, autonomic dysfunction, and diffuse brain injury. Diagnosis remains clinical. Management consists mainly of supportive care.