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

Advanced Vascular Access in Small Animal Emergency and Critical Care

In canine and feline patients presenting in a state of hemodynamic collapse, obtaining vascular access can be challenging. Delays in achieving vascular access interfere with delivery of patient care. In human medicine, definitions of difficult vascular access are variable and include the need for multiple placement attempts or involvement of specialized teams and equipment. Incidence and risk factors for difficult vascular access have not been well studied in veterinary patients, which limits understanding of how best to address this issue. Alternatives to percutaneous peripheral or central intravenous catheterization in dogs and cats include venous cutdowns, umbilical access in newborns, corpus cavernosum access in males, ultrasound-guided catheterization, and intraosseous catheterization. In recent years, advances in ultrasonography and intraosseous access techniques have made these more accessible to veterinary practitioners. These vascular access techniques are reviewed here, along with advantages, limitations, and areas for future study of each technique.

Point-of-care analyses of blood samples from intraosseous access in pre-hospital critical care

BACKGROUND

Intraosseous (IO) access is used for fluid and medication administration in emergency situations when difficulties with vascular access are encountered. IO access would be readily available to take samples for point-of-care (POC) analysis, but there is scarce evidence about the reliability of POC analysis of IO samples among emergency patients. The aim of this study was to evaluate the feasibility and reliability of POC analysis of IO samples in critically ill pre-hospital patients.

METHODS

We performed a prospective, observational study in 35 critically ill pre-hospital patients. After inserting a humeral IO needle, we immediately drew an IO sample. We compared the results to an arterial sample drawn from the same patient within 5 (blood gases) or 15 (other parameters) minutes. Samples were analysed with an i-STAT® POC analyser for blood gases, acid-base balance, electrolytes, glucose and haemoglobin. The agreement between each patient's IO and arterial samples was analysed using the Bland-Altman method. The results were compared to responses about acceptable bias on a questionnaire sent to 16 experienced emergency physicians.

RESULTS

The analysis was successful for 23 patients (70%). Higher age was associated with failed analyses. The average bias was acceptable for base excess, pH, standard bicarbonate, glucose, ionized calcium and sodium. IO potassium values were systematically higher than arterial values. IO haemoglobin values had widely varying agreement.

CONCLUSION

When vascular access is challenging, IO access can be used for emergency POC analyses to help guide clinical decision-making. However, the limitations of IO POC analyses must be carefully considered.

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.

Point-of-care laboratory analyses of intraosseous, arterial and central venous samples during experimental cardiopulmonary resuscitation

INTRODUCTION

Screening and correcting reversible causes of cardiac arrest (CA) are an essential part of cardiopulmonary resuscitation (CPR). Point-of-care (POC) laboratory analyses are used for screening pre-arrest pathologies, such as electrolyte disorders and acid-base balance disturbances. The aims of this study were to compare the intraosseous (IO), arterial and central venous POC values during CA and CPR and to see how the CPR values reflect the pre-arrest state.

METHODS

We performed an experimental study on 23 anaesthetised pigs. After induction of ventricular fibrillation (VF), we obtained POC samples from the IO space, artery and central vein simultaneously at three consecutive time points. We observed the development of the values during CA and CPR and compared the CPR values to the pre-arrest values.

RESULTS

The IO, arterial and venous values changed differently from one another during the course of CA and CPR. Base excess and pH decreased in the venous and IO samples during untreated VF, but in the arterial samples, this only occurred after the onset of CPR. The IO, arterial and venous potassium values were higher during CPR compared to the pre-arrest arterial values (mean elevations 4.4 mmol/l (SD 0.72), 3.3 mmol/l (0.78) and 2.8 mmol/l (0.94), respectively).

CONCLUSIONS

A dynamic change occurs in the common laboratory values during CA and CPR. POC analyses of lactate, pH, sodium and calcium within IO samples are not different from analyses of arterial or venous blood. Potassium values in IO, arterial and venous samples during CPR are higher than the pre-arrest arterial values.

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.

Comparison of Two Intraosseous Devices: The NIO Versus the EZ-IO by Novice Users-A Randomized Cross Over Trial

BACKGROUND

During resuscitation in the field, intraosseous (IO) access may be achieved using a variety of available devices, often attempted by inexperienced users.

AIM

We sought to examine the success rate and ease-of-use ratings of an IO device, the NIO® (New Intraosseous Persys Medical, Houston, TX, USA) in comparison to the Arrow® EZ-IO® (Teleflex Medical Research Triangle Park, NC, USA) by novice users.

METHODS

We performed a randomized crossover trial. The study model was a porcine hind leg which was cut distally in order to expose the marrow. The Study population was composed of pre-graduate medical students without prior experience in IO use, all designated future field physicians. The students underwent instruction and practiced the use of both devices. After practice completion, each student attempted a single IO insertion with both devices sequentially in randomized fashion. Success was defined as a flow of fluid through the bone marrow after a single IO attempt. Investigators which determined the success rate were blinded to the used device.

RESULTS

50 users (33 males, 17 females) participated in the trial, mean age of 21.7 years (±1). NIO users were successful in 92% (46/50) attempts while EZ-IO user success rate was 88% (44/50). NIO success rates were comparable to those of EZ-IO (p = NS). Results were similar when examining only the initial device used. Median score of ease of use was 4 (5 point Likert scale) in both devices (p = NS). 54% (27/50) of the participants preferred using the EZ-IO over the NIO (p = NS).

CONCLUSION

Novice users were equally successful in establishing IO access with the NIO® in comparison to the EZ-IO® in a porcine model.

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.

Use of intra-osseous access in adults: a systematic review

Background

Indications for intra-osseous (IO) infusion are increasing in adults requiring administration of fluids and medications during initial resuscitation. However, this route is rarely used nowadays due to a lack of knowlegde and training. We reviewed the current evidence for its use in adults requiring resuscitative procedures, the contraindications of the technique, and modalities for catheter implementation and skill acquisition.

Methods

A PubMed search for all articles published up to December 2015 was performed by using the terms “Intra-osseous” AND “Adult”. Additional articles were included by using the “related citations” feature of PubMed or checking references of selected articles. Editorials, comments and case reports were excluded. Abstracts of all the articles that the search yielded were independently screened for eligibility by two authors and included in the analysis after mutual consensus. In total, 84 full-text articles were reviewed and 49 of these were useful for answering the following question “when, how, and for which population should an IO infusion be used in adults” were selected to prepare independent drafts. Once this step had been completed, all authors met, reviewed the drafts together, resolved disagreements by consensus with all the authors, and decided on the final version.

Results

IO infusion should be implemented in all critical situations when peripheral venous access is not easily obtainable. Contraindications are few and complications are uncommon, most of the time bound to prolonged use. The IO infusion allows for blood sampling and administration of virtually all types of fluids and medications including vasopressors, with a bioavailability close to the intravenous route. Unfortunately, IO infusion remains underused in adults even though learning the technique is rapid and easy.

Conclusions

Indications for IO infusion use in adults requiring urgent parenteral access and having difficult intravenous access are increasing. Physicians working in emergency departments or intensive care units should learn the procedures for catheter insertion and maintenance, the contraindications of the technique, and the possibilities this access offers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1277-6) contains supplementary material, which is available to authorized users.

Analysis of intraosseous samples in endotoxemic shock--an experimental study in the anaesthetised pig

BACKGROUND

Intraosseous (IO) access is used in emergency situations to allow rapid initiation of treatment. IO access is also sometimes used for blood sampling, although data on accuracy of such sampling in critical illness are limited. There is also a potential risk that bone marrow fragments in IO samples may damage laboratory equipment. It is ethically questionable to perform a simultaneous comparison between IO and arterial/venous sampling in critically ill humans. We have, thus, studied the analytical performance of IO sampling in a porcine septic shock model using a cartridge-based analyser.

METHODS

Eight pigs with endotoxin-induced septic shock were sampled hourly for 6 h, and analysed for blood gases, acid base status, haemoglobin, glucose and lactate using point of care instruments. Samples were taken from three IO cannulae (tibia bilaterally, one with infusion, and humerus), one arterial and one venous. An interaction test was used to assess changes in agreement between methods over time. Bland–Altman plots were constructed to study bias between methods.

RESULTS

There were, to a varying extent, differences between IO and arterial/venous levels for all studied variables, but agreement did not change significantly during the experiment. A general finding was a large dispersion of differences between methods.

CONCLUSIONS

IO sample values should be treated with caution in this setting but may add useful information to the clinical picture. The tibia or humerus may be used for sampling. IO infusion decreases agreement, thus sampling during infusion should be avoided.