Are laboratory values in bone marrow aspirate predictable for venous blood in paediatric patients?

Intraosseous Specimens Submitted to the Laboratory: A Case Report and Review

Intraosseous (IO) devices are used for vascular access in settings where venous access is initially unobtainable, such as prehospital trauma care or cardiac arrest. While IO devices are effective for infusion of blood, fluids, and medications, there is limited data on the analytical equivalence of specimens taken out of IO devices and peripheral venous blood. Despite this, IO device manufacturers and clinical resources state that IO specimens can be submitted for laboratory analysis. As reported in this case, IO specimens may be drawn and labeled as 'peripheral blood'. IO specimens are not always caught by automated sample quality testing and may proceed through analysis without any warning signal to the laboratory. There are potential regulatory risks in accepting IO samples for analysis without validation. IO infusion is a valuable technique for vascular access in critically ill patients, but clinical laboratories will need to determine their own policies for identifying and handling IO specimens.

Analysing blood from intraosseous access: a systematic review

Intraosseous (IO) access is used widely as an optional vascular route for critically ill patients. It is still unclear whether the IO access can be used as a source for emergency blood samples. The aim of this study was to systematically review the existing literature on the usability of IO blood samples for analysing the parameters relevant to emergency care. We performed a data search from the Medline and Embase databases, the Cochrane Library and the Clinical trials registry. Animal studies and studies with healthy and ill adults and children were included in the search. The data were collected and reported following the PRISMA guidelines. The PROSPERO database registration number of this review is CRD42017064194. We found 27 studies comparing the blood samples from the IO space with arterial or venous samples, but only three of them followed the recommended guidelines for method comparison studies. The study populations were heterogeneous, and the sample sizes were relatively small (14, 17 and 20 individuals) in the three studies. The results of specific laboratory parameters were scarce and discordant. The evidence on the agreement between IO and arterial and venous samples is still weak. Existing studies with healthy volunteers and animal models provide important insight into the analyses of IO samples, but more evidence, especially from haemodynamically unstable patients, is needed for wider implementation of IO blood sampling in critically ill patients.

Intraosseous blood samples for point-of-care analysis: agreement between intraosseous and arterial analyses

Background

Point-of-care (POC) testing is highly useful when treating critically ill patients. In case of difficult vascular access, the intraosseous (IO) route is commonly used, and blood is aspirated to confirm the correct position of the IO-needle. Thus, IO blood samples could be easily accessed for POC analyses in emergency situations. The aim of this study was to determine whether IO values agree sufficiently with arterial values to be used for clinical decision making.

Methods

Two samples of IO blood were drawn from 31 healthy volunteers and compared with arterial samples. The samples were analysed for sodium, potassium, ionized calcium, glucose, haemoglobin, haematocrit, pH, blood gases, base excess, bicarbonate, and lactate using the i-STAT® POC device. Agreement and reliability were estimated by using the Bland-Altman method and intraclass correlation coefficient calculations.

Results

Good agreement was evident between the IO and arterial samples for pH, glucose, and lactate. Potassium levels were clearly higher in the IO samples than those from arterial blood. Base excess and bicarbonate were slightly higher, and sodium and ionised calcium values were slightly lower, in the IO samples compared with the arterial values. The blood gases in the IO samples were between arterial and venous values. Haemoglobin and haematocrit showed remarkable variation in agreement.

Discussion

POC diagnostics of IO blood can be a useful tool to guide treatment in critical emergency care. Seeking out the reversible causes of cardiac arrest or assessing the severity of shock are examples of situations in which obtaining vascular access and blood samples can be difficult, though information about the electrolytes, acid-base balance, and lactate could guide clinical decision making.

The analysis of IO samples should though be limited to situations in which no other option is available, and the results should be interpreted with caution, because there is not yet enough scientific evidence regarding the agreement of IO and arterial results among unstable patients.

Conclusions

IO blood samples are suitable for analysis with the i-STAT® point-of-care device in emergency care. The aspirate used to confirm the correct placement of the IO needle can also be used for analysis. The results must be interpreted within a clinical context while taking the magnitude and direction of bias into account.

Analysis of intraosseous blood samples using an EPOC point of care analyzer during resuscitation

BACKGROUND

In the early phases of resuscitation in a critically ill patient, especially those in cardiac arrest, intravenous (IV) access can be difficult to obtain. Intraosseous (IO) access is often used in these critical situations to allow medication administration. When no IV access is available, it is difficult to obtain blood for point of care analysis, yet this information can be crucial in directing the resuscitation. We hypothesized that IO samples may be used with a point of care device to obtain useful information when seconds really do matter.

METHODS

Patients presenting to the emergency department requiring resuscitation and IO placement were prospectively enrolled in a convenience sample. 17 patients were enrolled. IO and IV samples obtained within five minutes of one another were analyzed using separate EPOC® point of care analyzers. Analytes were compared using Bland Altman Plots and intraclass correlation coefficients.

RESULTS

In this analysis of convenience sampled critically ill patients, the EPOC® point of care analyzer provided results from IO samples. IO and IV samples were most comparable for pH, bicarbonate, sodium and base excess, and potentially for lactic acid; single outliers for bicarbonate, sodium and base excess were observed. Intraclass correlation coefficients were excellent for sodium and reasonable for pH, pO2, bicarbonate, and glucose. Correlations for other variables measured by the EPOC® analyzer were not as robust.

CONCLUSION

IO samples can be used with a bedside point of care analyzer to rapidly obtain certain laboratory information during resuscitations when IV access is difficult.

Analysis of thromboelastography, PT, APTT and fibrinogen in intraosseous and venous samples-an experimental study

Background

Laboratory analysis of coagulation is often important in emergencies. If vascular access is challenging, intraosseous catheterization may be necessary for treatment. We studied the analysis of coagulation parameters in intraosseous aspirate during stable conditions and after major haemorrhage in a porcine model.

Methods

Ten anesthetized pigs received central venous and intraosseous catheters and samples were taken for analysis of thromboelastography (TEG), prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen concentration. Analyses were repeated after removal of 50 % of the calculated blood volume and resuscitation with crystalloid. Intraosseous and venous values were compared.

Results

Bleeding and resuscitation resulted in haemodilution and hypotension. Median TEG reaction time was shorter in intraosseous than in venous samples before (1.6 vs 4.6 min) and after (1.6 vs 4.7 min) haemodilution. Median maximal amplitude was smaller in intraosseous samples at baseline (68.3 vs 76.4 mm). No major differences were demonstrated for the other TEG parameters. The intraosseous samples often coagulated in vitro, making analysis of PT, APTT and fibrinogen difficult. After haemodilution, TEG maximal amplitude and α-angle, and fibrinogen concentration, were decreased and PT increased.

Discussion

The intraosseous samples were clinically hypercoagulable and the TEG demonstrated a shortened reaction time. The reason for this may hypothetically be found in the composition of the IO aspirate or in the sampling technique. After 50 % haemorrhage and haemodilution, a clinically relevant decrease in fibrinogen concentration and a lower TEG maximal amplitude were observed.

Conclusions

Although the sample is small, these data indicate that intraosseous samples are hypercoagulable, which may limit their usefulness for coagulation studies. Major haemodilution only moderately affected the studied parameters.

Electronic supplementary material

The online version of this article (doi:10.1186/s13049-016-0318-0) contains supplementary material, which is available to authorized users.

Analysis of bone marrow aspiration fluid using automated blood cell counters

Cytomorphological examination of aspirate smears remains the basic method to diagnose hematologic disorders and to evaluate treatment-related changes. Last-generation hematological analyzers can count, besides cells normally circulating in peripheral blood, some types of immature and abnormal cells, such as erythroblasts and immature granulocytes. The complex nature of bone marrow fluid, however, has prevented until now the routine utilization of blood cell counters in this area. Recent studies have shown the possibility of using bone marrow fluid as a substitute for peripheral blood for clinical tests in particular situations and for repetitive cytologic examinations in specific clinical and research fields.

Analysis of intraosseous samples using point of care technology--an experimental study in the anaesthetised pig

BACKGROUND

Intraosseous access is an essential method in emergency medicine when other forms of vascular access are unavailable and there is an urgent need for fluid or drug therapy. A number of publications have discussed the suitability of using intraosseous access for laboratory testing. We aimed to further evaluate this issue and to study the accuracy and precision of intraosseous measurements.

METHODS

Five healthy, anaesthetised pigs were instrumented with bilateral tibial intraosseous cannulae and an arterial catheter. Samples were collected hourly for 6h and analysed for blood gases, acid base status, haemoglobin and electrolytes using an I-Stat point of care analyser.

RESULTS

There was no clinically relevant difference between results from left and right intraosseous sites. The variability of the intraosseous sample values, measured as the coefficient of variance (CV), was maximally 11%, and smaller than for the arterial sample values for all variables except SO2. For most variables, there seems to be some degree of systematic difference between intraosseous and arterial results. However, the direction of this difference seems to be predictable.

CONCLUSION

Based on our findings in this animal model, cartridge based point of care instruments appear suitable for the analysis of intraosseous samples. The agreement between intraosseous and arterial analysis seems to be good enough for the method to be clinically useful. The precision, quantified in terms of CV, is at least as good for intraosseous as for arterial analysis. There is no clinically important difference between samples from left and right tibia, indicating a good reproducibility.

Intraosseous vascular access: A review

Intraosseous cannulation is an increasingly common means of achieving vascular access for the administration of fluids and medications during the emergent resuscitation of both paediatric and adult patients. Improved tools and techniques for intraosseous vascular access have recently been developed, enabling the healthcare provider to choose from a wide range of devices and insertion sites. Despite its increasing popularity within the adult population, and decades of use in the paediatric population, questions remain regarding the safety and efficacy of intraosseous infusion. Although various potential complications of intraosseous cannulation have been theorized, few serious complications have been reported. This article aims to provide a review of the current literature on intraosseous vascular access, including discussion on the various intraosseous devices currently available in the market, the advantages and disadvantages of intraosseous access compared to conventional vascular access methods, complications of intraosseous cannulation and current recommendations on the use of this approach.

Intraosseous anesthesia in hemodynamic studies in children with cardiopathy

BACKGROUND AND OBJECTIVES

Intraosseous (IO) access has been used with good results in emergency situations, when venous access is not available for fluids and drugs infusion. The objective of this study was to evaluate IO a useful technique for anesthesia and fluids infusion during hemodynamic studies and when peripheral intravascular access is unobtainable. The setting was an university hospital hemodynamics unit, and the subjects were twenty one infants with congenital heart disease enrolled for elective hemodynamic study diagnosis.

METHODS

This study compared the effectiveness of IO access in relation to IV access for infusion of anesthetics agents (ketamine, midazolam, and fentanyl) and fluids during hemodynamic studies. The anesthetic induction time, procedure duration, anesthesia recovery time, adequate hydration, and IV and IO puncture complications were compared between groups.

RESULTS

The puncture time was significantly smaller in IO group (3.6 min) that in IV group (9.6 min). The anesthetic onset time (56.3 second) for the IV group was faster than IO group (71.3 second). No significant difference between groups were found in relation to hydration (IV group, 315.5 mL vs IO group, 293.2 mL), and anesthesia recovery time (IO group, 65.2 min vs IV group, 55.0 min). The puncture site was reevaluated after 7 and 15 days without signs of infection or other complications.

CONCLUSIONS

Results showed superiority for IO infusion when considering the puncture time of the procedure. Due to its easy manipulation and efficiency, hydration and anesthesia by IO access was satisfactory for hemodynamic studies without the necessity of other infusion access.

Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

The goal of therapy for bradycardia or tachycardia is to rapidly identify and treat patients who are hemodynamically unstable or symptomatic due to the arrhythmia. Drugs or, when appropriate, pacing may be used to control unstable or symptomatic bradycardia. Cardioversion or drugs or both may be used to control unstable or symptomatic tachycardia. ACLS providers should closely monitor stable patients pending expert consultation and should be prepared to aggressively treat those with evidence of decompensation.

A new study of intraosseous blood for laboratory analysis

CONTEXT

Intraosseous (IO) blood is frequently used to establish a blood chemistry profile in critically ill patients. Questions remain regarding the reliability of IO blood for laboratory analysis and established criteria regarding the amount of marrow/blood to waste before taking an IO sample are not available.

OBJECTIVES

To evaluate IO-derived blood for routine laboratory blood tests needed in the care of critically ill patients and to determine the amount of marrow/blood to waste before drawing blood from the IO space for laboratory analysis.

DESIGN

Blood samples were drawn from peripheral veins of 10 volunteers. Within 5 minutes, 2 IO blood samples were obtained; one following 2 mL of waste and another following 6 mL of waste. Samples were analyzed for complete blood count and chemistry profile. Values were analyzed using Pearson correlation coefficients. Levels of significance were determined using the t distribution. Mean values for the draws were calculated and compared, with the intravenous blood sample serving as a control for the IO samples.

RESULTS

There was a significant correlation between intravenous and IO samples for red blood cell counts and hemoglobin and hematocrit levels but not for white blood cell counts and platelet counts. There was a significant correlation between intravenous and IO samples for glucose, blood urea nitrogen, creatinine, chloride, total protein, and albumin concentrations but not for sodium, potassium, CO(2), and calcium levels.

CONCLUSIONS

When venous blood cannot be accessed, IO blood aspirate may serve as a reliable alternate, especially for hemoglobin and hematocrit levels and most analytes in a basic blood chemistry profile. Exceptions are CO(2) levels and platelet counts, which may be lower, and white blood cell counts, which may appear elevated.

Intraosseous access

BACKGROUND

Vascular access is of paramount importance in the care of the critically ill patient. When central or peripheral intravenous access cannot be accomplished in a timely manner, intraosseous access and infusion is a rapid and safe alternative for the delivery of fluids, medications, and blood products. The resurgence of the use of intraosseous access in the 1980s led to the development of new methods and devices that facilitate insertion.

OBJECTIVES

This article discusses general indications, contraindications, and complications of intraosseous access and infusion, focusing on new devices and their insertion.

DISCUSSION

Current research is focused on product innovation and improving drug delivery using intraosseous autoinjectors, finding new anatomic sites for placement, and expanding the use of different intraosseous devices to the adult population.

CONCLUSIONS/SUMMARY

New, improved intraosseous systems provide health care providers with choices beyond traditional manual intraosseous access for administering fluids.

Intraosseous infusion: a review of methods and novel devices

This is a review article of intraosseous infusion methods and devices.

Intraosseous drug administration in children and adults during cardiopulmonary resuscitation

OBJECTIVE

To review and assess the available literature on the use of intraosseous (IO) drug administration during cardiopulmonary resuscitation, addressing the benefits and risks of using this method of drug delivery in children and adults.

DATA SOURCES

The MEDLINE (1950-July 2007) database was searched for pertinent abstracts, using the key term intraosseous infusions. Additional references were obtained from the bibliographies of the articles reviewed. Manufacturer Web sites were used to obtain information about IO insertion devices.

STUDY SELECTION AND DATA EXTRACTION

All available English-language clinical trials, retrospective studies, and review articles describing IO drug administration were reviewed. Studies conducted in animal models to evaluate the effectiveness and safety of IO drug administration were also included.

DATA SYNTHESIS

IO access uses the highly vascularized bone marrow to deliver fluids and medications during cardiopulmonary resuscitation. This route, developed in the 1940s, has been revived in the past decade as a means of achieving rapid vascular access when intravenous access cannot be obtained. The primary advantage of IO access is the high success rate (approximately 80%). Most trained providers can place an IO line within 1-2 minutes. A number of small-scale studies and retrospective reviews have established the usefulness of this route for the delivery of many commonly used resuscitation drugs. In addition, animal models have demonstrated rapid drug delivery to the systemic circulation. While all resuscitation drugs can be given by the IO route, administration of ceftriaxone, chloramphenicol, phenytoin, tobramycin, and vancomycin may result in lower peak serum concentrations. The most common adverse effect seen with IO use, extravasation, has been reported in 12% of patients. Compartment syndrome, osteomyelitis, and tibial fracture are rare, but have also been reported.

CONCLUSIONS

IO administration is a safe and effective method for delivering drugs during cardiopulmonary resuscitation. It should be considered whenever intravenous access cannot be rapidly obtained.

Blood flow and microdialysis in the human femoral head

BACKGROUND

If it would be possible to detect lack of flow and/or the development of ischemia in bone, we might have a way of predicting whether a broken bone will heal. We established microdialysis (MD) and laser Doppler (LD) flow measurement in the human femoral head in order to be able to detect ischemia and measure changes in blood flow.

MATERIAL AND METHODS

In 9 patients undergoing total hip arthroplasty for primary osteoarthrosis, two MD catheters were inserted into the femoral head through two drill holes after the blood flow had been visualized by LD. Then primary samples were collected with the femoral head in situ; thereafter, the head was removed and samples were collected over the following 4 hours ex vivo. The variables obtained by MD were concentrations of glucose, lactate, pyruvate, and glycerol in extracellular fluid.

RESULTS

The results showed development of ischemia with a statistically significant decrease in glucose concentration and elevation of the lactate/pyruvate ratio over time. The LD showed flow with the femoral head in situ and lack of flow when the femoral head was removed.

INTERPRETATION

The use of MD was established in the human femoral head. Ischemic levels were detected within 2 h of cessation of blood flow in most patients.

The International Liaison Committee on Resuscitation (ILCOR) consensus on science with treatment recommendations for pediatric and neonatal patients: pediatric basic and advanced life support

This publication contains the pediatric and neonatal sections of the 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations (COSTR). The consensus process that produced this document was sponsored by the International Liaison Committee on Resuscitation (ILCOR). ILCOR was formed in 1993 and consists of representatives of resuscitation councils from all over the world. Its mission is to identify and review international science and knowledge relevant to cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) and to generate consensus on treatment recommendations. ECC includes all responses necessary to treat life-threatening cardiovascular and respiratory events. The COSTR document presents international consensus statements on the science of resuscitation. ILCOR member organizations are each publishing resuscitation guidelines that are consistent with the science in this consensus document, but they also take into consideration geographic, economic, and system differences in practice and the regional availability of medical devices and drugs. The American Heart Association (AHA) pediatric and the American Academy of Pediatrics/AHA neonatal sections of the resuscitation guidelines are reprinted in this issue of Pediatrics (see pages e978-e988). The 2005 evidence evaluation process began shortly after publication of the 2000 International Guidelines for CPR and ECC. The process included topic identification, expert topic review, discussion and debate at 6 international meetings, further review, and debate within ILCOR member organizations and ultimate approval by the member organizations, an Editorial Board, and peer reviewers. The complete COSTR document was published simultaneously in Circulation (International Liaison Committee on Resuscitation. 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2005;112(suppl):73-90) and Resuscitation (International Liaison Committee on Resuscitation. 2005 International Consensus Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Resuscitation. 2005;67:271-291). Readers are encouraged to review the 2005 COSTR document in its entirety. It can be accessed through the CPR and ECC link at the AHA Web site: www.americanheart.org. The complete publication represents the largest evaluation of resuscitation literature ever published and contains electronic links to more detailed information about the international collaborative process. To organize the evidence evaluation, ILCOR representatives established 6 task forces: basic life support, advanced life support, acute coronary syndromes, pediatric life support, neonatal life support, and an interdisciplinary task force to consider overlapping topics such as educational issues. The AHA established additional task forces on stroke and, in collaboration with the American Red Cross, a task force on first aid. Each task force identified topics requiring evaluation and appointed international experts to review them. A detailed worksheet template was created to help the experts document their literature review, evaluate studies, determine levels of evidence, develop treatment recommendations, and disclose conflicts of interest. Two evidence evaluation experts reviewed all worksheets and assisted the worksheet reviewers to ensure that the worksheets met a consistently high standard. A total of 281 experts completed 403 worksheets on 275 topics, reviewing more than 22000 published studies. In December 2004 the evidence review and summary portions of the evidence evaluation worksheets, with worksheet author conflict of interest statements, were posted on the Internet at www.C2005.org, where readers can continue to access them. Journal advertisements and e-mails invited public comment. Two hundred forty-nine worksheet authors (141 from the United States and 108 from 17 other countries) and additional invited experts and reviewers attended the 2005 International Consensus Conference for presentation, discussion, and debate of the evidence. All 380 participants at the conference received electronic copies of the worksheets. Internet access was available to all conference participants during the conference to facilitate real-time verification of the literature. Expert reviewers presented topics in plenary, concurrent, and poster conference sessions with strict adherence to a novel and rigorous conflict of interest process. Presenters and participants then debated the evidence, conclusions, and draft summary statements. Wording of science statements and treatment recommendations was refined after further review by ILCOR member organizations and the international editorial board. This format ensured that the final document represented a truly international consensus process. The COSTR manuscript was ultimately approved by all ILCOR member organizations and by an international editorial board. The AHA Science Advisory and Coordinating Committee and the editor of Circulation obtained peer reviews of this document before it was accepted for publication. The most important changes in recommendations for pediatric resuscitation since the last ILCOR review in 2000 include: Increased emphasis on performing high quality CPR: "Push hard, push fast, minimize interruptions of chest compression; allow full chest recoil, and don't provide excessive ventilation" Recommended chest compression-ventilation ratio: For lone rescuers with victims of all ages: 30:2 For health care providers performing 2-rescuer CPR for infants and children: 15:2 (except 3:1 for neonates) Either a 2- or 1-hand technique is acceptable for chest compressions in children Use of 1 shock followed by immediate CPR is recommended for each defibrillation attempt, instead of 3 stacked shocks Biphasic shocks with an automated external defibrillator (AED) are acceptable for children 1 year of age. Attenuated shocks using child cables or activation of a key or switch are recommended in children <8 years old. Routine use of high-dose intravenous (IV) epinephrine is no longer recommended. Intravascular (IV and intraosseous) route of drug administration is preferred to the endotracheal route. Cuffed endotracheal tubes can be used in infants and children provided correct tube size and cuff inflation pressure are used. Exhaled CO2 detection is recommended for confirmation of endotracheal tube placement. Consider induced hypothermia for 12 to 24 hours in patients who remain comatose following resuscitation. Some of the most important changes in recommendations for neonatal resuscitation since the last ILCOR review in 2000 include less emphasis on using 100% oxygen when initiating resuscitation, de-emphasis of the need for routine intrapartum oropharyngeal and nasopharyngeal suctioning for infants born to mothers with meconium staining of amniotic fluid, proven value of occlusive wrapping of very low birth weight infants <28 weeks' gestation to reduce heat loss, preference for the IV versus the endotracheal route for epinephrine, and an increased emphasis on parental autonomy at the threshold of viability. The scientific evidence supporting these recommendations is summarized in the neonatal document (see pages e978-e988).

[Vascular access in emergency paediatric anaesthesia]

There is very little literature to guide the young practitioner in caring for a child that needs emergency surgery and has difficult venous access. Questionnaires were sent to 89 members of the Swiss Paediatric Anaesthesia Society and to the heads of Anaesthesia Departments of Swiss teaching hospitals. Two typical case records were presented, both of which were characterised by the fact that 2-3 peripheral venous cannulation attempts were unsuccessful. Case A: a young child with a fracture of the radius and case B an infant with upper gastrointestinal ileus. The anaesthetists were then questioned regarding their preferences for optimal treatment. The majority would proceed with further attempts and, if these still failed, intramuscular or inhalational induction of anaesthesia was suggested as a reasonable choice for case A. However, for case B, a femoral venous or intraosseous access to the venous system was judged to be the safest method. On the basis of our inquiry and a literature search, a priority list was developed to suggest the best possible techniques for vascular access and alternative anaesthesia induction techniques for emergency paediatric procedures.

Use of intraosseous blood for repeated hematologic and biochemical analyses in healthy pigs

OBJECTIVE

To evaluate the clinical and histologic effects of repeated intraosseous (IO) needle placement in domestic pigs and determine whether blood and serum obtained intraosseously could be used for CBC and biochemical analyses.

ANIMALS

5 healthy 10-week-old pigs.

PROCEDURE

An IO needle was placed in the proximomedial region of the tibia of anesthetized pigs every other week for 2 months, and IO blood was obtained for CBC and serum biochemical analyses. Results were compared with those obtained for blood collected at the same time from the auricular vein. Two weeks after the final samples were obtained, pigs were euthanatized and tibias were processed for histologic examination.

RESULTS

Clinical abnormalities, including lameness, were not detected following IO needle placement. Histologic examination revealed only mild multifocal periosteal fibrosis and slight thickening of the periosteum without evidence of osteomyelitis. Chloride, creatinine, glucose, total protein, sodium, and BUN concentrations, alanine transaminase and gamma glutamyl transpeptidase activities, RBC count, mean corpuscular volume, and Hct did not significantly differ between IO and venous samples. However, aspartate transaminase activity, potassium, hemoglobin, and mean corpuscular hemoglobin concentrations, mean corpuscular hemoglobin, and platelet and WBC counts were significantly different.

CONCLUSION AND CLINICAL RELEVANCE

Repeated placement of 10 needles may be a safe and clinically useful method to obtain serial blood samples from domestic pigs, particularly when other vascular sites are not accessible. Intraosseous blood can be used for many of the tests comprising CBC and serum biochemical analyses.

Can blood taken from intraosseous cannulations be used for blood analysis?

Intraosseous infusion is increasingly finding application for venous access to infuse drugs and fluids in paediatric resuscitation including burns. The aim of this study was to determine the feasibility of using blood samples taken from the bone marrow cavity for routine blood analysis. In paediatric resuscitation where alternative venous access is not available this could prove valuable. Peripheral venous blood samples were compared with blood obtained from the bone marrow cavity in patients undergoing bone marrow aspiration for the investigation of possible medical pathology. Haemoglobin, haematocrit, sodium, urea, creatinine, and calcium levels values were sufficiently similar to be clinically useful. The potassium level was elevated in most bone marrow samples and the difference from peripheral venous samples variable. Great caution should be exercised in their interpretation. Glucose levels should also be interpreted with care. In conclusion, blood samples obtained intraosseously may give a useful guide to peripheral blood levels of some haematological and biochemical variables. This is potentially useful where a peripheral venous sample cannot be obtained. The values must be interpreted with care. Whether these findings can be extended to paediatric patients who are not haemodynamically stable has not been assessed.

Intraosseous blood gases during hypothermia: correlation with arterial, mixed venous, and sagittal sinus blood

OBJECTIVE

Especially in pediatric patients with severe hypothermia, intraosseous access may be more readily available than intravascular access during an early phase of treatment and therefore, may be helpful to optimize management. The purpose of this study was to determine whether intraosseous blood gases are comparable with arterial, mixed venous, and sagittal sinus blood gases during different degrees of hypothermia.

DESIGN

Prospective, descriptive laboratory investigation using a porcine model.

SETTING

University hospital laboratory.

SUBJECTS

Twelve anesthetized, 12- to 16-wk-old domestic pigs weighing 30-35 kg.

INTERVENTIONS

Volume-controlled ventilated animals were instrumented with arterial, pulmonary artery, sagittal sinus, and 16-gauge intraosseous catheters. Blood samples were obtained from each site every 15 mins during surface cooling with crushed ice until mean +/- SEM core temperature decreased from 38.5+/-0.1 degrees C [101.3+/-0.2 degrees F] to 27+/-0.5 degrees C [80.5+/-0.9 degrees F] over 2 hrs.

MEASUREMENTS AND MAIN RESULTS

Intraindividual correlation of Pco2 and pH values were determined as the difference (delta) between intraosseous and reference blood samples. With hypothermia, absolute values of Pco2 decreased and pH increased in samples from all sites. At 27 degrees C, intraosseous--arterial delta P(CO2) and delta pH (mean +/- 95% confidence intervals) were 2.6+/-10.6 torr [0.35+/-1.4 kPa] and -0.11+/-0.07 units; intraosseous - mixed venous were 0.4+/-12.2 torr [0.05+/-1.6 kPa] and -0.06+/-0.08 units; and intraosseous - sagittal sinus were -7.3+/-16 torr [-0.97+/-2.1 kPa] and 0.001+/-0.14 units, respectively. Intraosseous Pco2 was not comparable to end-tidal values (deltaP(CO2) 17.4+/-14.6 torr [2.3+/-1.9 kPa]), and intraosseous lactate did not correlate with arterial, mixed venous, or sagittal sinus values.

CONCLUSIONS

During hypothermia, intraosseous P(CO2) values were predictable for mixed venous Pco2 and arterial P(CO2). Intraosseous pH values also correlated with mixed venous and sagittal sinus blood samples. Accordingly, interpretation of blood gas values obtained from bone marrow aspirates may be helpful to adjust ventilation and optimize fluid and drug therapy during the early treatment of patients with severe hypothermia.

Use of intraosseous blood to assess blood chemistries and hemoglobin during cardiopulmonary resuscitation with drug infusions

OBJECTIVE

To compare intraosseous with central venous blood samples for biochemical analyses and hemoglobin levels during cardiopulmonary resuscitation (CPR) and during cardiopulmonary resuscitation with infusion of sodium bicarbonate, epinephrine, and saline boluses through the intraosseous site.

DESIGN

Prospective, complete repeated measures study.

SETTING

An animal laboratory at a university medical center.

SUBJECTS

Thirty-two piglets (mean weight, 30 [range, 24-35] kg).

INTERVENTIONS

Animals were anesthetized, instrumented, and subjected to hypoxic cardiac arrest. An intraosseous cannula was inserted into the tibia, and animals were randomly assigned to one of five groups: heparinized saline (n = 6), epinephrine infusions only (n = 6), saline infusions only (n = 6), sodium bicarbonate infusions only (n = 8), and epinephrine, saline, and sodium bicarbonate infusions through the same site (n = 6). CPR (chest compressions and mechanical ventilation) was performed in all groups. Simultaneous blood samples were taken from the central venous and intraosseous sites before arrest and after 5 and 30 mins of CPR.

MEASUREMENTS AND MAIN RESULTS

There were no differences (p < .05) in sodium, potassium, magnesium, lactate, and calcium values of intraosseous and central venous blood at the baseline and during 5 mins of CPR with infusions through the intraosseous cannula. At 30 mins, differences were apparent in magnesium, potassium, and sodium values between groups when the intraosseous cannula was used for infusions as well as sampling. Intraosseous potassium, glucose, and magnesium values were lower and sodium values were higher than central venous blood levels. No differences were seen at all sampling intervals if small-volume heparinized saline was given through the intraosseous site. Hemoglobin values were lower in the intraosseous group after 30 mins of CPR and infusions through the intraosseous site. After 30 mins of CPR, all hemoglobin values from the intraosseous site were <10 g/100 mL.

CONCLUSION

Intraosseous and central venous blood biochemical and hemoglobin values were similar during hemodynamic stability and throughout 30 mins of resuscitation if no drugs were given through the intraosseous site. However, differences existed after 30 mins of CPR and infusions through the intraosseous site. Laboratory values may be erroneous when intraosseous blood is used during periods of resuscitation of >5 mins if drugs and fluid boluses have also been infused through the site. For reliable values, an intraosseous site for sampling only may be reasonable.