Budget Impact and Cost-Effectiveness of Intravenous Meloxicam to Treat Moderate-Severe Postoperative Pain

INTRODUCTION

This study assesses the budget impact and cost-effectiveness of intravenous meloxicam (MIV) to treat moderate-severe acute postoperative pain in adults.

METHODS

A two-part Markov cohort model captured the pharmacoeconomic impact of MIV versus non-opioid intravenous analgesics (acetaminophen, ibuprofen, ketorolac) among a hypothetical adult cohort undergoing selected inpatient procedures and experiencing moderate-severe acute postoperative pain: Part 1 (postoperative hour 0 to discharge, cycled hourly), health states were defined by pain level. Pain transition rates, adverse event probabilities, and concomitant opioid utilization were derived from a network meta-analysis. Part 2 (discharge to week 52, cycled weekly), health states were defined by the presence/absence of pain-related readmission and opioid use disorder as determined by literature-based inputs relating to pain control outcomes. Healthcare utilization and direct medical costs were derived from an administrative claims database analysis. Primary outcomes were the incremental cost per member per month (PMPM) and cost per quality-adjusted life year (QALY) gained. Scenario, univariate, and probabilistic sensitivity analyses were conducted. The model assumed a private payer perspective in the USA (no discounting, 2019 US$).

RESULTS

Modeled outcomes indicated MIV was associated with lower accumulated postoperative pain, fewer adverse events, and less opioid utilization for most procedures and comparators, with longer-term outcomes also generally favoring MIV. The budget impact of MIV was - $0.028 PMPM. From a cost-effectiveness perspective, MIV had lower costs and better outcomes for all comparisons except against ketorolac in orthopedic procedures where the former was cost-effective but not cost saving ($95,925/QALY). Scenario and sensitivity analyses indicated that modeled outcomes were robust to alternative inputs and underlying input uncertainty. Differences in direct medical costs were driven by reduced costs attributable to length of stay and opioid-related adverse drug events.

CONCLUSION

MIV was associated with modeled clinical and economic benefits compared to commonly used non-opioid intravenous analgesics.

Pruritus, neuraxial morphine and recrudescence of oral herpes simplex and treatment: an educational review in obstetric patients

Neuraxial opioids are well known to cause itching, which may be challenging to treat. Neuraxial morphine has been demonstrated to cause recrudescent herpes simplex viruses (HSV-1), especially in women during labor and childbirth with neuraxial analgesia, and may be an occult etiology of refractory itching. This educational review summaries the clinical and epidemiological characteristics associated with recrudescent HSV-1 in patients treated with neuraxial opioids, especially morphine.

Blood Substitutes and Oxygen Therapeutics: A Review

Despite the exhaustive search for an acceptable substitute to erythrocyte transfusion, neither chemical-based products such as perfluorocarbons nor hemoglobin-based oxygen carriers have succeeded in providing a reasonable alternative to allogeneic blood transfusion. However, there remain scenarios in which blood transfusion is not an option, due to patient's religious beliefs, inability to find adequately cross-matched erythrocytes, or in remote locations. In these situations, artificial oxygen carriers may provide a mortality benefit for patients with severe, life-threatening anemia. This article provides an up-to-date review of the history and development, clinical trials, new technology, and current standing of artificial oxygen carriers as an alternative to transfusion when blood is not an option.

Local and Intra-articular Administration of Nonsteroidal Anti-inflammatory Drugs for Pain Management in Orthopedic Surgery

BACKGROUND

Although growing evidence demonstrates the benefits of locally administered nonsteroidal anti-inflammatory drugs (NSAIDs) for postoperative pain management, there is ongoing debate regarding NSAID use in orthopedic surgery.

AREAS OF UNCERTAINTY

Current data largely support a local site of NSAID action and suggest that effective pain control can be achieved with delivery of NSAIDs intra-articularly (IA) and/or locally at the site of injury, where they can block peripheral production of inflammatory mediators and may desensitize nociceptors. Improvements in postoperative pain control with locally administered NSAIDs have been widely reported in the total joint arthroplasty literature and may offer benefits in patient's undergoing arthroscopic procedures and those with osteoarthritis as well. The purpose of this review is to examine the available evidence in the literature regarding the efficacy and safety profile of the use of local and IA NSAIDs in orthopedic surgery.

DATA SOURCES

Narrative literature review using keywords, expert opinion, either during or from live conference.

THERAPEUTIC ADVANCES

Local and IA administration of NSAIDs for pain management in orthopedic surgery.

CONCLUSION

There is convincing evidence that NSAIDs administered locally in and around the joint reduce postoperative pain scores and opioid consumption in patients undergoing total joint arthroplasty, yet further research is required regarding the risks of potential chondrotoxicity and the inhibition of bone and soft-tissue healing with locally administered NSAIDs.

Efficacy of non-opioid analgesics to control postoperative pain: a network meta-analysis

Background

The aim of this network meta-analysis (NMA) was to evaluate the safety and efficacy of intravenous (IV) Meloxicam 30 mg (MIV), an investigational non-steroidal anti-inflammatory drug (NSAID), and certain other IV non-opioid analgesics for moderate-severe acute postoperative pain.

Methods

We searched PubMed and CENTRAL for Randomized Controlled Trials (RCT) (years 2000–2019, adult human subjects) of IV non-opioid analgesics (IV NSAIDs or IV Acetaminophen) used to treat acute pain after abdominal, hysterectomy, bunionectomy or orthopedic procedures. A Bayesian NMA was conducted in R to rank treatments based on the standardized mean differences in sum of pain intensity difference from baseline up to 24 h postoperatively (sum of pain intensity difference: SPID 24). The probability and the cumulative probability of rank for each treatment were calculated, and the surface under the cumulative ranking curve (SUCRA) was applied to distinguish treatments on the basis of their outcomes such that higher SUCRA values indicate better outcomes. The study protocol was prospectively registered with by PROSPERO (CRD42019117360).

Results

Out of 2313 screened studies, 27 studies with 36 comparative observations were included, producing a treatment network that included the four non-opioid IV pain medications of interest (MIV, ketorolac, acetaminophen, and ibuprofen). MIV was associated with the largest SPID 24 for all procedure categories and comparators. The SUCRA ranking table indicated that MIV had the highest probability for the most effective treatment for abdominal (89.5%), bunionectomy (100%), and hysterectomy (99.8%). MIV was associated with significantly less MME utilization versus all comparators for abdominal procedures, hysterectomy, and versus acetaminophen in orthopedic procedures. Elsewhere MME utilization outcomes for MIV were largely equivalent or nominally better than other comparators. Odds of ORADEs were significantly higher for all comparators vs MIV for orthopedic (gastrointestinal) and hysterectomy (respiratory).

Conclusions

MIV 30 mg may provide better pain reduction with similar or better safety compared to other approved IV non-opioid analgesics. Caution is warranted in interpreting these results as all comparisons involving MIV were indirect.

Perioperative bleeding and non-steroidal anti-inflammatory drugs: An evidence-based literature review, and current clinical appraisal

Patient satisfaction measures and the opioid epidemic have highlighted the need for effective perioperative pain management. Multimodal analgesia, including non-steroidal anti-inflammatory drugs (NSAIDs), have been shown to maximize pain relief and reduce opioid consumption, but are also associated with potential perioperative bleeding risks.A multidisciplinary panel conducted a clinical appraisal of bleeding risks associated with perioperative NSAID use. The appraisal consisted of review and assessment of the current published evidence related to the statement "In procedures with high bleeding risk, NSAIDs should always be avoided perioperatively." We report the presented literature and proceedings of the subsequent panel discussion and national pilot survey results. The authors' assessment of the statement based on current evidence was compared to the attempted national survey data, which revealed a wide range of opinions reflecting the ongoing debate around this issue in a small number of respondents.The appraisal concluded that caution is warranted with respect to perioperative use of NSAIDs. However, summarily excluding NSAIDs from perioperative use based on potential bleeding risks would be imprudent. It is recommended that NSAID use be guided by known patient- and procedure-specific factors to minimize bleeding risks while providing effective pain relief.

Article Commentary: Defining New Directions for More Effective Management of Surgical Pain in the United States: Highlights of the Inaugural Surgical Pain Congress™

Despite advances in pharmacologic options for the management of surgical pain, there appears to have been little or no overall improvement over the last two decades in the level of pain experienced by patients. The importance of adequate and effective surgical pain management, however, is clear, because inadequate pain control 1) has a wide range of undesirable physiologic and immunologic effects; 2) is associated with poor surgical outcomes; 3) has increased probability of readmission; and 4) adversely affects the overall cost of care as well as patient satisfaction. There is a clear unmet need for a national surgical pain management consensus task force to raise awareness and develop best practice guidelines for improving surgical pain management, patient safety, patient satisfaction, rapid postsurgical recovery, and health economic outcomes. To comprehensively address this need, the multidisciplinary Surgical Pain Congress™ has been established. The inaugural meeting of this Congress (March 8 to 10, 2013, Celebration, Florida) evaluated the current surgical pain management paradigm and identified key components of best practices.

Platelet Function: Meloxicam Intravenous in Whole Blood Samples From Healthy Volunteers

Nonsteroidal anti‐inflammatory drugs (NSAIDs) are effective treatments for pain but may induce bleeding events due to platelet dysfunction associated with inhibition of cyclooxygenase (COX)‐1 impairing thromboxane production. An intravenous nanocrystal formulation of meloxicam, a COX‐2 preferential nonsteroidal anti‐inflammatory drug, is under development for the treatment of moderate to severe pain. This single‐center ex vivo study evaluated the effect of meloxicam intravenous and ketorolac on platelet function in whole blood samples from healthy volunteers. Each whole blood sample was aliquoted to allow analysis using a platelet function analyzer under negative control (untreated), positive control (2 therapeutic ketorolac concentrations), and meloxicam intravenous (1 therapeutic, 3 supratherapeutic concentrations) using both collagen with epinephrine and collagen with adenosine diphosphate reagent cartridges. The platelet function analyzer determines closure time by simulating platelet adhesion and aggregation following vascular injury. The final analysis set included data from 8 subjects. The collagen with adenosine diphosphate analysis (sensitive to thrombocytopathies) showed no significant differences in closure time for meloxicam‐ or ketorolac‐treated samples and untreated control. The collagen with epinephrine analysis (sensitive to aspirin‐induced platelet abnormalities) produced no significant difference in closure time between any meloxicam concentration and untreated control. Ketorolac was associated with significantly longer closure times vs untreated control at both the 2.5‐ and 5‐µg/mL concentrations (P = .003 and .0257, respectively) and vs meloxicam at several concentrations. Similar results were observed when all analyzed samples were included. Meloxicam intravenous had no significant effect on closure times at therapeutic or supratherapeutic concentrations in this ex vivo study.

Intravenous non-opioid analgesia for peri- and postoperative pain management: a scientific review of intravenous acetaminophen and ibuprofen

Pain is a predictable consequence following operations, but the management of postoperative pain is another challenge for anesthesiologists and inappropriately controlled pain may lead to unwanted outcomes in the postoperative period. Opioids are indeed still at the mainstream of postoperative pain control, but solely using only opioids for postoperative pain management may be connected with risks of complications and adverse effects. As a consequence, the concept of multimodal analgesia has been proposed and is recommended whenever possible. Acetaminophen is one of the most commonly used analgesic and antipyretic drug for its good tolerance and high safety profiles. The introduction of intravenous form of acetaminophen has led to a wider flexibility of its use during peri- and postoperative periods, allowing the early initiation of multimodal analgesia. Many studies have revealed the efficacy, safety and opioid sparing effects of intravenous acetaminophen. Intravenous ibuprofen has also shown to be well tolerated and demonstrated to have significant opioid sparing effects during the postoperative period. However, the number of randomized controlled trials confirming the efficacy and safety is small and should be used in caution in certain group of patients. Intravenous acetaminophen and ibuprofen are important options for multimodal postoperative analgesia, improving pain and patient satisfaction.

Effects of hemoglobin-based oxygen carriers on blood coagulation

For many decades, Hemoglobin-based oxygen carriers (HBOCs) have been central in the development of resuscitation agents that might provide oxygen delivery in addition to simple volume expansion. Since 80% of the world population lives in areas where fresh blood products are not available, the application of these new solutions may prove to be highly beneficial (Kim and Greenburg 2006). Many improvements have been made to earlier generation HBOCs, but various concerns still remain, including coagulopathy, nitric oxide scavenging, platelet interference and decreased calcium concentration secondary to volume expansion (Jahr et al. 2013). This review will summarize the current challenges faced in developing HBOCs that may be used clinically, in order to guide future research efforts in the field.

Defining new directions for more effective management of surgical pain in the United States: highlights of the inaugural Surgical Pain Congress™

Despite advances in pharmacologic options for the management of surgical pain, there appears to have been little or no overall improvement over the last two decades in the level of pain experienced by patients. The importance of adequate and effective surgical pain management, however, is clear, because inadequate pain control 1) has a wide range of undesirable physiologic and immunologic effects; 2) is associated with poor surgical outcomes; 3) has increased probability of readmission; and 4) adversely affects the overall cost of care as well as patient satisfaction. There is a clear unmet need for a national surgical pain management consensus task force to raise awareness and develop best practice guidelines for improving surgical pain management, patient safety, patient satisfaction, rapid postsurgical recovery, and health economic outcomes. To comprehensively address this need, the multidisciplinary Surgical Pain Congress™ has been established. The inaugural meeting of this Congress (March 8 to 10, 2013, Celebration, Florida) evaluated the current surgical pain management paradigm and identified key components of best practices.

Crosslinked, polymerized, and PEG-conjugated hemoglobin-based oxygen carriers: clinical safety and efficacy of recent and current products

Blood substitutes, especially hemoglobin based oxygen carriers (HBOC) have been widely studied and reviewed over the past 30 years. The development of HBOCs was highlighted by crosslinking to minimize adverse effects. However, even early attempts at single crosslinking using alpha-alpha crosslinks or diaspirin crosslinking failed clinical trials due to renal morbidity and increased mortality. In fact, preclinical trials may have predicted failure of this first generation product, DCLHb (diaspirin-crosslinked Hb) (HemAssist ®, Baxter). In the 1980's, three small biopharmaceutical companies developed "second generation" HBOCs, the first being Hemosol with their raffinose crosslinked HBOC, hemoglobin- raffimer. The other two development programs modified the HBOC using glutaraldehyde polymerization, in an attempt to further alleviate the toxicities of the "first" generation HBOCs. This paper will review the definitive clinical trials of the two polymerized HBOCs, Biopure's hemoglobin glutamer-250 (bovine) and Northfield's polymerized human Hb, pegylated HBOC and Sangart's peg-conjugated HBOC, with an introductory brief review of Hemosol's hemoglobinraffimer. The paper will then introduce the newest polymerized hemoglobin, zero-linked hemoglobin polymer, which has not yet undergone clinical trials but has undergone some preclinical work that will be discussed in a section on this product. As a new generation HBOC, zero-linked hemoglobin polymer may begin to address the issues presented by the first two generations of HBOCs, and may hold promise as a universally applicable HBOC.

Intravenous acetaminophen

Acetaminophen has unique analgesic and antipyretic properties. It is globally recommended as a first-line agent for the treatment of fever and pain due to its few contraindications. Acetaminophen lacks the significant gastrointestinal and cardiovascular side effects associated with nonsteroidal anti-inflammatory drugs and narcotics. An intravenous formulation of acetaminophen is available in Europe and is currently undergoing extensive clinical development for use in the United States. This use may have important implications for management of postoperative pain and fever. This review summarizes recent clinical trial experiences with intravenous acetaminophen for the treatment of postoperative pain and fever in adult and pediatric subjects.

Sugammadex: cyclodextrins, development of selective binding agents, pharmacology, clinical development, and future directions

Neuromuscular blocking agents are widely used in perioperative medicine to aid in endotracheal intubation, facilitate surgery, and in critical care/emergency medicine settings. Muscle relaxants have profound clinical uses in current surgical and intensive care and emergency medical therapy. This article reviews cyclodextrins, development of selective binding agents, clinical development, and future directions of sugammadex.

Blood Substitute Resuscitation as a Treatment Modality for Moderate Hypovolemia

Blood substitute resuscitation as a treatment modality for moderate hypovolemia (approximately 40% blood loss) in a canine model has been evaluated using Oxyglobin (Biopure Hemoglobin Glutamer-200/ Bovine; a hemoglobin-based oxygen-carrier) and Hespan (6% hetastarch; a nonoxygen-carrier) as resuscitants. Autologous (shed) blood served as control. Nine dogs were studied--after splenectomy, each dog was hemorrhaged (32-36 mL/kg; MAP = approximately 50 mmHg) and randomly assigned to the three resuscitation groups. Microvascular, systemic function and oxygenation characteristics were monitored and/or measured simultaneously in prehemorrhagic (baseline), posthemorrhagic and postresuscitation phases for correlation-real-time microvascular changes in the bulbar conjunctiva were noninvasively measured via computer-assisted intravital microscopy and systemic function and oxygenation changes were monitored and/or measured via instrumentation and devices incorporated into our bioengineering station in an operating room setting. Blood chemistry was also studied for relevant measurements. Prehemorrhagic microvascular characteristics were similar in all animals (venular diameter = 41 +/- 12 microm, A:V ratio = approximately 1:2, red-cell velocity = 0.5 +/- 0.3 mm/s). All animals also showed similar prehemorrhagic systemic function and oxygenation measurements comparable to a previous study and were consistent with normal measurements in dogs. At the completion of hemorrhaging to achieve moderate hypovolemia (approximately 40% blood loss with MAP at approximately 50 mmHg), all nine animals showed similar significant (P < 0.01) posthemorrhagic microvascular changes, including approximately 17% decrease in diameter (34 +/- 7 microm), A:V ratio = variable, and approximately 80% increase in velocity (0.9 +/- 0.5 mm/s). All animals also showed similar significant (P < 0.01) posthemorrhagic systemic function and oxygenation changes, with decreases in Hct, aHb(total), MPAP, MAP, SAP, DAP, CO, SVI, CaO2, and CvO2 and increases in HR and lactic acidosis. Shed blood (control) resuscitation restored posthemorrhagic microvascular changes close to prehemorrhagic values (diameter = 39 +/- 6 microm, A:V ratio = approximately 1:2, velocity = 0.6 +/- 0.4 mm/s). Oxyglobin and Hespan restored microvascular changes in similar manner close to prehemorrhagic values (Oxyglobin: diameter = 38 +/- 3 microm, A:V ratio = approximately 1:2, velocity = 0.6 +/- 0.4 mm/s; Hespan: diameter = 38 +/- 7 microm, A:V ratio = 1:2, velocity = 0.5 +/- 0.4 mm/s). After resuscitation, shed blood (control) restored all systemic function and oxygenation changes close to prehemorrhagic values. However, both Oxyglobin and Hespan resuscitation restored systemic function changes, but not oxygenation changes, to prehemorrhagic values. This was an interesting finding because of the different oxygen-carrying capability of Oxyglobin (oxygen-carrying) and Hespan (nonoxygen-carrying). The result suggests that either volume replenishment alone (and not oxygen-carrying capability) is needed to treat moderate hypovolemia or oxygenation measurements obtained by standard methods (oximetry, blood chemistry) may not reflect tissue oxygenation levels.

Comparison of Treatment Modalities for Hemorrhagic Shock

Allogeneic blood resuscitation is the treatment of choice for hemorrhagic shock. When blood is unavailable, plasma expanders, including crystalloids, colloids, and blood substitutes, may be used. Another treatment modality is vasopressin, a vasoconstrictor administered to redistribute blood flow, increase venous return, and maintain adequate cardiac output. While much information exists on systemic function and oxygenation characteristics following treatment with these resuscitants, data on their effects on the microcirculation and correlation of real-time microvascular changes with changes in systemic function and oxygenation in the same animal are lacking. In this study, real-time microvascular changes during hemorrhagic shock treatment were correlated with systemic function and oxygenation changes in a canine hemorrhagic shock model (50-55% total blood loss with a MAP of 45-50 mmHg as a clinical criterion). Following splenectomy and hemorrhage, the dogs were assigned to five resuscitation groups: autologous/shed blood, hemoglobin-based oxygen carrier/Oxyglobin, crystalloid/saline, colloid/Hespan (6% hetastarch), and vasopressin. Systemic function and oxygenation changes were continuously monitored and periodically measured (during various phases of the study) using standard operating room protocols. Computer-assisted intravital video-microscopy was used to objectively analyze and quantify real-time microvascular changes (diameter, red-cell velocity) in the conjunctival microcirculation. Measurements were made during pre-hemorrhagic (baseline), post-hemorrhagic (pre-resuscitation), and post-resuscitation phases of the study. Pre-hemorrhagic microvascular variables were similar in all dogs (venular diameter = 42+/-4 microm, red-cell velocity = 0.55+/-0.5 mm/sec). All dogs showed significant (P < 0.05) post-hemorrhagic microvascular changes: approximately 20% decrease in venular diameter and approximately 30% increase in red-cell velocity, indicative of sympathetic effects arising from substantial blood loss. Microvascular changes correlated with post-hemorrhagic systemic function and oxygenation changes. All resuscitation modalities except vasopressin restored microvascular and systemic function changes close to pre-hemorrhagic values. However, only autologous blood restored oxygenation changes to pre-hemorrhagic levels. Vasopressin treatment resulted in further decreases in venular diameter (approximately 50%) as well as red-cell velocity (approximately 70%) without improving cardiac output. Our results suggested that volume replenishment - not oxygen-carrying capability - played an important role in pre-hospital/en route treatment for hemorrhagic shock. Vasopressin treatment resulted in inadvertent detrimental outcome without the intended benefit.

Impact of a Didactic Lecture on Professionalism in Increasing Knowledge Amongst Faculty and Residents in an Academic Department

BACKGROUND

The ACGME require compliance with six core competencies - professionalism is one of them. Non-professional behavior is the most common reason for disciplinary action against physicians by the Medical Boards. Professionalism should be taught and measured at an early stage of the physician's career.

METHODS

IRB approval was obtained to carry out this study. The subjects were faculty and residents of the anesthesia department. The pretest was administered and followed by a lecture and discussion on professionalism by Anesthesia faculty. This was followed by the posttest. The test consisted of 22 questions related to professionalism.

RESULTS

Eighteen subjects completed the pretest while 14 completed the posttest. Age range was 39.72 +/- 10.58. The pretest scores were 59.6+/- 12.5, while the posttest scores were 57.8 +/- 12.8. Correct answers for each question ranged from 5.6 to 100% for the pretest and 0 to 100% for the post test. Correct answers for each subject ranged from 31.8 to 77.3% for both pre and post tests. No statistically significant difference was found in scores between the pre-test and post-test.

CONCLUSIONS

Based on these initial findings, teaching professionalism is extremely difficult and feed back from the participants using tools like a pretest and post-test may help identify if knowledge transfer has actually occurred. Teaching and assessment of professionalism should take into consideration the students pre-existing knowledge-base, cultural background and environment.

Blood substitutes as pharmacotherapies in clinical practice

PURPOSE OF REVIEW

To discuss the development and current status of blood substitutes, including hemoglobin-based oxygen carriers (HBOCs) and perfluorocarbons. Research in this field offers an important view into the future of transfusion medicine in the operating room, as well as in trauma and combat arenas.

RECENT FINDINGS

A pivotal multinational phase III trial of the Biopure product HBOC-201 (Hemopure) has been completed in orthopedic surgery patients. HBOC-201 consists of polymerized bovine hemoglobin and has already been well tolerated in patients undergoing cardiopulmonary bypass and abdominal aortic reconstruction. Polyheme is a polymerized human hemoglobin in early phase III clinical trials with trauma patients, having infused up to 10,000 ml, with efficacy apparently demonstrated in phase II. The Sangart product, Hemospan, is currently undergoing phase II trials.

SUMMARY

Polymerized hemoglobin preparations have proven most successful in clinical trials due to their improved side-effect profile. The goal is to evaluate blood substitutes with enhanced intravascular retention, reduced osmotic activity, and attenuated hemodynamic derangements such as vasoconstriction. Although not without substantial morbidity and mortality, the current safety of allogeneic blood transfusion demands that comparative studies show minimal adverse effects, as well as efficacy and potential for novel applications.

Effects of low-volume hemoglobin glutamer-200 versus normal saline and arginine vasopressin resuscitation on systemic and skeletal muscle blood flow and oxygenation in a canine hemorrhagic shock model

OBJECTIVE

To test the hypothesis that low-volume resuscitation with hemoglobin glutamer-200 improves hemodynamic function and tissue oxygenation, whereas arginine vasopressin resuscitation improves blood pressures more than low-volume saline or hemoglobin glutamer infusion but compromises systemic and muscle blood flow and oxygenation.

DESIGN

Randomized laboratory investigation.

SETTING

University research facility.

SUBJECTS

Nineteen dogs.

INTERVENTIONS

Dogs were instrumented to determine heart rate; arterial, central venous, pulmonary arterial, and pulmonary arterial occlusion pressures; cardiac output; and quadriceps muscle blood flow and oxygen tension (PMo2). Total and plasma hemoglobin, oxygen content, lactate, pH, standard base excess, and arginine vasopressin levels were determined, and systemic oxygen delivery (Do2I) and extraction ratio were calculated. Measurements were made before and 30 mins following hemorrhage. Dogs were resuscitated over 60 mins with saline (8.5 mL/kg), arginine vasopressin (0.4 IU/kg bolus plus 0.08 IU x kg x min), or 1:1 diluted hemoglobin glutamer-200. Recordings were then repeated. Subsequently, animals received 30 mL/kg shed blood (60 mL x kg x hr), and recordings were repeated immediately and 1 hr later.

MEASUREMENTS AND MAIN RESULTS

Hemorrhage ( approximately 52 mL/kg) caused characteristic changes in hemodynamic, hematologic, systemic PMo2, and acid-base variables. Saline resuscitation increased both Do2I and muscle perfusion by 42% and 51%, while arginine vasopressin treatment reduced heart rate by 31% and increased mean arterial pressure by 22% but not cardiac output, Do2I, or muscle blood flow, resulting in a further decrease of PMo2 by 68% and worse metabolic acidosis. Hemoglobin glutamer-200 infusion caused systemic and pulmonary vasoconstriction, however, without deterioration of cardiac output, Do2I, muscle blood flow, or PMo2 despite lack of oxygen content increase. Blood transfusion restored most variables.

CONCLUSIONS

Low-volume crystalloid or hemoglobin glutamer-200 resuscitation posthemorrhage may improve (but not restore) macro- and microvascular functions and tissue oxygenation, while arginine vasopressin infusion may only improve blood pressures and result in lower overall systemic perfusion compared with low-volume saline or hemoglobin glutamer-200 treatment and worsening of anaerobic conditions in skeletal muscle.

Effects of isovolemic resuscitation with hemoglobin-based oxygen carrier Hemoglobin glutamer-200 (bovine) on systemic and mesenteric perfusion and oxygenation in a canine model of hemorrhagic shock: a comparison with 6% hetastarch solution and shed blood

OBJECTIVE

To study Hemoglobin glutamer-200 bovine (Hb-200), 6% hetastarch (HES) and shed whole blood (WB) resuscitation in canine hemorrhagic shock.

STUDY DESIGN

Prospective laboratory investigation. Animals Twelve adult dogs [29 +/- 1 kg (mean +/- SD)].

METHODS

Anesthetized dogs were instrumented for recording systemic and mesenteric hemodynamic parameters and withdrawal of arterial, mixed and mesenteric venous blood, in which hematological, oxygenation, blood gas and acid-bases variables were determined. Recordings were made before [baseline (BL)], after 1 hour of hypovolemia and immediately and 3 hours post-resuscitation with 30 mL kg(-1) of either Hb-200, HES, or WB.

RESULTS

Blood withdrawal (average 34 +/- 2 mL kg(-1)) caused significant hemodynamic changes, metabolic acidosis and hyperlactatemia characteristic for hemorrhagic shock. Only WB transfusion restored all variables. Hemoglobin glutamer-200 bovine infusion returned most hemodynamic parameters including cardiac output and mesenteric arterial blood flow to BL but increased mean arterial pressure above BL (p < 0.05). However, Hb-200 failed to restore total Hb and arterial oxygen content (CaO2), leaving systemic (DO2I) and mesenteric O2 delivery (DO2Im) below BL (p < 0.05). Nevertheless, acid-base variables recovered completely after Hb-200 resuscitation, and met-hemoglobin (Met-Hb) levels increased (p < 0.05). Hetastarch resuscitation returned hemodynamic variables to or above BL but further decreased total Hb and CaO2, preventing recovery of sDO2I and mDO2I (p < 0.05). Thus, systemic and mesenteric O2 extraction stayed above BL (p < 0.05) while acid-base variables recovered to BL, although slower than in Hb-200 and WB groups (p < 0.05).

CONCLUSIONS AND CLINICAL RELEVANCE

Resuscitation with Hb-200 seemed to resolve metabolic acidosis and lactatemia more rapidly than HES, but not WB; yet it is not superior to HES in improving DO2I and DO2Im. The hyperoncotic property of solutions like Hb-200 that results in rapid volume expansion with more homogenous microvascular perfusion and the ability to facilitate diffusive O2 transfer accelerating metabolic recovery may be the key mechanisms underlying their beneficial effects as resuscitants.

Evaluation of the effect of perioperative rofecoxib treatment on pain control and clinical outcomes in patients recovering from gynecologic abdominal surgery: a randomized, double-blind, placebo-controlled clinical study

BACKGROUND AND OBJECTIVES

In this randomized, placebo-controlled, double-blind study, the efficacy and safety of rofecoxib 50 mg was evaluated in patients undergoing major abdominal gynecologic surgery.

METHODS

Patients were randomized to receive rofecoxib 50 mg (n = 81) or placebo (n = 83) approximately 2 hours before total abdominal hysterectomy or myomectomy and once daily over the ensuing 4 days. Clinical measurements included average daily opioid use over the 5-day period (primary endpoint), pain intensity on movement, and opioid-related side effects.

RESULTS

Patients receiving rofecoxib required 32% less (P = .001) intravenous and oral opioids to relieve their postoperative pain from days 1 to 5 (primary endpoint), used 21% less (P = .011) on day 1, and 42% less (P < .001) from days 2 to 5. The rofecoxib group experienced less pain upon movement (P < .001), less sedation (P = .007), and a 24% reduction in the rate of antiemetic intake (P = .037) over the first 72 hours postsurgery. Earlier mean times to first flatus (-10.1 hours, P = .001), first bowel movement (-14.1 hours, P = .037), and time to hospital discharge (-10.9 hours; 95% confidence interval, -17.1 to -4.7) occurred in the rofecoxib group. There were no significant intergroup differences in blood loss, wound healing, or overall adverse experiences.

CONCLUSIONS

Compared with placebo, perioperative administration of rofecoxib 50 mg provided significant opioid sparing, significantly better pain control, improved clinical outcomes, and was well tolerated.

Systemic function, oxygenation and microvascular correlation during treatment of hemorrhagic shock with blood substitutes

Systemic function and oxygenation changes during hemorrhagic shock treatment were continuously monitored and correlated with real-time microvascular changes. After splenectomy, each dog (n = 12) was hemorrhaged (MAP = approximately 50 mmHg; approximately 40% blood loss = 32-36 ml/kg) and randomly assigned to 4 resuscitation groups: autologous/shed blood, hemoglobin-based oxygen-carrier/Oxyglobin, crystalloid/saline, and colloid/Hespan. Systemic function and oxygenation changes were continuously monitored and measured using standard operating room protocols. Computer-assisted intravital microscopy was used to non-invasively videotape and objectively analyze and quantify real-time microvascular changes in the conjunctival microcirculation. All measurements were made during pre-hemorrhagic (baseline), post-hemorrhagic and post-resuscitation phases of the study. Pre-hemorrhagic microvascular changes were similar in all 12 dogs (venular diameter = 43 +/- 12 microm; red-cell velocity = 0.6 +/- 0.2 mm/s). All dogs showed similar significant (P<0.01) post-hemorrhagic microvascular changes: approximately 20% decrease in venular diameter; approximately 80% increase in red-cell velocity. These microvascular changes correlated with post-hemorrhagic systemic function and oxygenation changes. The resuscitations restored microvascular changes to pre-hemorrhagic values; the microvascular reversals also correlated with post-resuscitation systemic function changes in all groups. However, only shed blood resuscitation restored oxygenation level close to pre-hemorrhagic values. All 12 dogs survived resuscitation treatments despite differences in oxygen-carrying capability between groups.

Efficacy and safety of single and repeated administration of 1 gram intravenous acetaminophen injection (paracetamol) for pain management after major orthopedic surgery

BACKGROUND

Intravenous acetaminophen injection (paracetamol) is marketed in Europe for the management of acute pain. A repeated-dose, randomized, double-blind, placebo-controlled, three-parallel group study was performed to evaluate the analgesic efficacy and safety of intravenous acetaminophen as compared with its prodrug (propacetamol) and placebo. Propacetamol has been available in many European countries for more than 20 yr.

METHODS

After orthopedic surgery, patients reporting moderate to severe pain received either 1 g intravenous acetaminophen, 2 g propacetamol, or placebo at 6-h intervals over 24 h. Patients were allowed "rescue" intravenous patient-controlled analgesia morphine. Pain intensity, pain relief, and morphine use were measured at selected intervals. Safety was monitored through adverse event reporting, clinical examination, and laboratory testing.

RESULTS

One hundred fifty-one patients (intravenous acetaminophen: 49; propacetamol: 50; placebo: 52) received at least one dose of study medication. The intravenous acetaminophen and propacetamol groups differed significantly from the placebo group regarding pain relief from 15 min to 6 h (P < 0.05) and median time to morphine rescue (intravenous acetaminophen: 3 h; propacetamol: 2.6 h; placebo: 0.8 h). Intravenous acetaminophen and propacetamol significantly reduced morphine consumption over the 24-h period: The total morphine doses received over 24 h were 38.3 +/- 35.1 mg for intravenous acetaminophen, 40.8 +/- 30.2 mg for propacetamol, and 57. 4 +/- 52.3 mg for placebo, corresponding to decreases of -33% (19 mg) and -29% (17 mg) for intravenous acetaminophen and propacetamol, respectively. Drug-related adverse events were reported in 8.2%, 50% (most of them local), and 17.3% of patients treated with intravenous acetaminophen, propacetamol, and placebo, respectively.

CONCLUSION

Intravenous acetaminophen, 1 g, administered over a 24-h period in patients with moderate to severe pain after orthopedic surgery provided rapid and effective analgesia and was well tolerated.

Does Methemoglobin from Oxidized Hemoglobin-Based Oxygen Carrier (Hemoglobin Glutamer-200) Interfere with Lactate Measurement (YSI 2700 SELECT??? Biochemistry Analyzer)?

In this study, we validated the accuracy of lactate measurements (YSI 2700 SELECT glucose/lactate analyzer) in the presence of methemoglobin from an oxidized bag of hemoglobin-based oxygen carrier (Met-HBOC), hemoglobin glutamer-200 (Oxyglobin; Biopure Corp). Different combinations of concentrated L-lactate solution, pooled canine plasma, and Plasmalyte A were added to 4 sample groups (1%, 10%, 20%, and 40% Met-HBOC [1.3 g/dL]) to yield linear increases in lactate concentration in consecutive samples. The mean difference between measured and calculated lactate was -5.1 mg/dL (1% Met-HBOC), -5.8 mg/dL (10% Met-HBOC), -4.6 mg (20% Met-HBOC), and -8.5 mg/dL (40% Met-HBOC). The root mean square error was 6.5 mg/dL, 7.4 mg/dL, 6.8 mg/dL, and 10.3 mg/dL, respectively. The Bland-Altman correlation (r) was r = -0.94 (P = 0.01), r = -0.91 (P < 0.001), r = -0.90 (P < 0.001), and r = -0.94 (P < 0.001), respectively, where r = 0 for perfect agreement between measured and calculated values. Results indicate that true lactate levels in the presence of Met-HBOC are underestimated when measured by an YSI 2700 analyzer independent of the amount of Met-HBOC present. When interpreting lactate concentrations from a patient with a HBOC present in plasma, underestimation of true lactate levels may occur unrelated to methemoglobin concentrations.

Lactate Measurement Interference by Hemoglobin-Based Oxygen Carriers (Oxyglobin??, Hemopure??, and Hemolink???)

We sought to determine whether hemoglobin-based oxygen carriers (HBOCs), hemoglobin glutamer-200 [bovine] (HBOC-200, Oxyglobin), hemoglobin glutamer-250 [bovine] (HBOC-201, Hemopure), and hemoglobin raffimer (Hemolink) interfere with the accuracy of lactate measurements. Combinations of concentrated L-lactate solution, HBOC, and blood or plasma with added PlasmaLyte-A were added to sample tubes to make a linear and constant increase in lactate concentration in consecutive samples. Sample lactate concentrations ranged from 5-110 mg/dL (0.6-12 mm) (physiological reference range: 5-20 mg/dL [0.56-2.2 mm]). Comparisons were made between machine measured lactate concentrations and calculated lactate concentrations. For Hb glutamer-250, the average difference between measured and calculated lactate concentrations was -5.1 mg/dL (-0.57 mm) (LX-20), with greater underestimation at larger lactate concentrations. For Hb raffimer, the average difference was -2.2 mg/dL (-0.24 mm) (LX-20). The veterinary product, Hb glutamer-200, was tested on 3 analyzers (LX-20(R), YSI 1500, and YSI 2300). The YSI 1500 was the most accurate instrument with the mean difference between measured minus calculated lactate being +1.3 mg/dL versus -2.6 mg/dL (YSI 2300) and -8.4 mg/dL (LX-20). The clinical implications of this study are that with increasing levels of an HBOC in plasma, lactate interpretation may become inaccurate, especially at larger lactate concentrations, causing underestimation of measured lactate values and possible under-treatment of the patient. Therefore, caution must be exercised when interpreting lactate results when a HBOC is present in plasma.

Confirmation and quantification of hemoglobin-based oxygen carriers in equine and human plasma by hyphenated liquid chromatography tandem mass spectrometry

Oxyglobin (OXY) and Hemopure (HMP) are produced from bovine hemoglobin (Hb) and were developed for the treatment of anemia in animal and human patients, respectively. Hemolink (HML) is a blood substitute of human Hb origin under development. The ability of these agents to carry oxygen in circulating blood and their promise to improve oxygen delivery to tissues supports the potential for their abuse in equine and human athletes. To deter athletes from abuse of these agents, a method has been developed for the detection, confirmation and quantification of OXY, HMP, and HML in equine and human plasma. OXY, HMP, and HML were extracted from equine or human plasma by solid-phase extraction using Bond Elut ENV cartridges and were digested by trypsin at 37 degrees C for 3 h. The tryptic digests were analyzed by LC-MS/MS, and tryptic peptides specific for bovine and human Hbs were targeted. OXY and HMP were detected, quantified, and confirmed using the y14 ion and b8 ion of the tryptic peptide from bovine Hb alpha chain residues 69-90, and HML was quantified using the tryptic peptide from human Hb alpha chain residues 63-91. The limit of detection for OXY in equine plasma and HML in human and equine plasma was 50 and 250 microg/mL for HMP in human and equine plasma. The limit of confirmation was 250 microg/mL for OXY in equine plasma, 500 microg/mL for HML in human and equine plasma, and 1000 microg/mL for HMP in human and equine plasma. The linear range for quantification was 50-5000 microg/mL for OXY in equine plasma and for HML in human and equine plasma, and 250-5000 microg/mL for HMP in human and equine plasma. The intraday and interday CV were less than 17% for quantification of OXY in equine plasma with external calibration. OXY was stable for more than 30 days at -20 and -70 degrees C. OXY was detected and quantified in equine plasma up to 24 h following administration of a very low dose of OXY (32.5 g in 2 x 125 mL per horse), and its presence in equine plasma was confirmed up to 12 h postadministration.

Does lead interfere with hemoglobin-based oxygen carrier (HBOC) function? A pilot study of lead concentrations in three approved or tested HBOCs and oxyhemoglobin dissociation with HBOCs and/or bovine blood with varying lead concentrations

We measured lead concentrations in three hemoglobin-based oxygen carriers (HBOCs; Oxyglobin, Hemopure, and Hemolink) and compared them with lead concentrations from blood-bank blood. Oxyhemoglobin dissociation was measured with large concentrations of lead in bovine HBOC, with or without bovine blood, and in bovine blood. Samples of each were prepared by combining one with normal saline (control), the second with small lead concentrations (22 micro g/dL), and the third with toxic lead concentrations (70 micro g/dL). They were blended in 2 tonometers at oxygen concentrations (2.5%, 5%, 8%, 10%, 21%, and 95%) with 5% CO(2) and the remainder nitrogen for 5 min per sample after a 15-min wash-in with each level of oxygen and were measured with co-oximetry. Oxygen saturation was plotted against PO(2), fitting fourth-order polynomial nonlinear regression to the data. The lead concentrations of the three HBOCs were 0.51, 0.22, 0.40 micro g/dL. There were no clinically important differences of the oxyhemoglobin dissociation curves as a function of lead concentration. The lead concentrations of the three tested HBOCs were small and no larger than the average for blood-bank blood. The presence of increasing concentrations of lead in either concentrated solution of bovine HBOC or a 1:1 mixture of bovine HBOC and native bovine blood does not appear to affect hemoglobin oxygenation in an acute in vitro model of increased lead concentrations.

IMPLICATIONS

Gunshot wounds rapidly increase circulating lead concentrations. Lead concentrations are small in three hemoglobin-based oxygen carriers (HBOCs), and HBOCs and/or bovine blood do not appear to be affected by lead concentrations in terms of immediate oxygen on-loading and off-loading. HBOCs may be useful in patients with gunshot wounds.

Arterial oxygenation and oxygen delivery after hemoglobin-based oxygen carrier infusion in canine hypovolemic shock: a dose-response study

OBJECTIVE

To compare effects of 6% hetastarch (Hextend) and hemoglobin-based oxygen carrier hemoglobin glutamer-200 (Hb-200) (bovine; Oxyglobin) on hemodynamics, arterial oxygen content, and systemic oxygen delivery in a canine hemorrhagic shock model.

DESIGN

Randomized laboratory investigation.

SETTING

University surgical research facility.

SUBJECTS

Twenty-four anesthetized healthy, adult, mongrel dogs (28 +/- 1 kg; 7 female, 17 male).

INTERVENTIONS

Dogs were instrumented for determinations of heart rate, arterial, central venous, pulmonary arterial, and pulmonary arterial occlusion pressures, and cardiac index. Total solids, colloid oncotic pressure, arterial oxygen content, Hb, lactate, pH, and blood gases were analyzed in blood samples. Recordings were made before, after 1 hr of hemorrhagic shock, and immediately and 3 hrs after infusion of either 30 mL/kg hetastarch (group 1), 10 mL/kg Hb-200 + 20 mL/kg hetastarch (group 2), 20 mL/kg Hb-200 + 10 mL/kg hetastarch (group 3), or 30 mL/kg Hb-200 (group 4).

MEASUREMENTS AND MAIN RESULTS

Hemorrhage (35 +/- 1 mL/kg) reduced mean arterial pressure to 50 mm Hg and caused significant decreases in total Hb, mean pulmonary arterial pressure, cardiac index and systemic oxygen delivery, increases in heart rate and systemic vascular resistance, and lactic acidosis. In group 1, hetastarch infusion was accompanied by increases of pulmonary arterial pressure, cardiac index, and blood oxygen extraction above baseline, and decreases of systemic vascular resistance, total Hb, total solids, arterial oxygen content, and systemic oxygen delivery below baseline (p <.05). Other data returned to baseline. In groups 2 to 4, hemodynamic functions (except pulmonary arterial pressure) recovered, yet neither total Hb (i.e., plasma and red blood cell Hb) nor arterial oxygen content increased despite increases in plasma Hb of 2 to 5 g/dL and proportionate increases in total solids. Systemic oxygen delivery improved dose-dependently with Hb-200 but did not return to baseline (p <.05), reaching values comparable to hetastarch group only at 30 mL/kg Hb-200. In all groups, oxygen extraction remained above baseline. Metabolic acidosis and lactatemia resolved significantly faster in groups 2 to 4, and colloid oncotic pressure after resuscitation was greater in groups 2 to 4 than in controls (p <.05).

CONCLUSIONS

In hemorrhagic shock, Hb-200 infusion may not improve oxygen delivery more than hetastarch, likely due to hemodilution caused by its high colloid oncotic pressure, but may facilitate diffusive oxygen transport to tissues.

Validity of arterial and mixed venous oxygen saturation measurements in a canine hemorrhage model after resuscitation with varying concentrations of hemoglobin-based oxygen carrier

In this study, we evaluated the validity of saturation measurements in mixed venous and arterial blood during posthemorrhagic anemia and resuscitation with varying levels of hemoglobin-based oxygen carrier (Hemoglobin glutamer-200 [bovine]; Oxyglobin [Hb-200]). Nineteen anesthetized, splenectomized, mixed-breed dogs were anesthetized (two were excluded from the data because they did not survive the exsanguination, supporting the validity of the model). Their pulmonary arteries were cannulated with the Abbott QVUE Oximetrix 3 catheter. An 18-gauge catheter was placed in the femoral artery, and a reusable Nellcor probe was applied to the tongue. Mixed venous and arterial samples were drawn at baseline, after 40% hemorrhage (to keep arterial pressure at 50 mm Hg), and postresuscitation with 30 mL/kg of 6% hetastarch in lactated Ringer's solution (n = 4), 10 mL/kg of Hb-200, 20 mL/kg of hetastarch (n = 6), 20 mL/kg of Hb-200, and 10 mL/kg of hetastarch (n = 7). Samples were compared with oxygen content from the LEXO2CON-K oxygen analyzer, and oxygen content was calculated for all values from the monitors. Results were compared by using analysis of variance. There was good correlation (0.97 > or = r > or = 0.92) for the measured versus calculated hemoglobin oxygen saturation values at baseline. After resuscitation, the correlation between calculated and measured values of oxygen content was significantly smaller for all tested instruments. The values of oxygen content calculated from the oxygen saturation monitor and from the oximetric pulmonary artery can deviate by as much as 20% from directly measured values. We conclude that the administration of this oxygen therapeutic may interfere with the values of some monitors.

IMPLICATIONS

This study evaluated oxygen saturation monitors in a canine model of acute blood loss and resuscitation with a blood substitute and found that these may interfere with the monitors' results in a dose-dependent way.

Validation of oxygen saturation measurements in a canine model of hemoglobin-based oxygen carrier infusion

This study was designed to validate oxygen saturation measurements from the NOVA CO-Oximeter (NOVA Biomedical Corporation, Waltham, MA), the i-STAT System (Sensor Devices, Waukesha, WI), and the Corning 170 blood gas analyzer (Bayer Corporation, East Walpole, MA) under conditions similar to the clinical application of a hemoglobin-based oxygen carrier (HBOC, hemoglobin glutamer-200 [bovine]; Oxyglobin, Biopure Corporation, Cambridge, MA). A canine model was used for both in vitro and in vivo experiments. In vivo experiments were conducted in a canine laboratory, and in vitro experiments were conducted in a tonometry laboratory. Study subjects were six mixed-breed dogs, each weighing approximately 30 kg. In the first set of experiments, the target blood po(2) levels were reached by tonometry. In the second set of experiments, quantitative measurements of total oxygen content with the LEXO2CON-K (HOSPEX Fiberoptics, Chestnut Hill, MA) were performed, immediately followed by measurements with the NOVA CO-Oximeter and the i-STAT system. HBOC was added in concentrations of 16.2, 32.5, 65, and 97.5 g/L. To analyze the clinical significance of the differences in the results obtained with the each investigated instrument, blood samples from dogs treated with HBOC after acute hemorrhagic shock were used. Oxygen saturation, oxygen content, and po(2) were measured. There was a strong correlation between the oxygen saturation values measured with the investigated instruments in samples after tonometry and known po(2). The total calculated oxygen content varied by 5% based on results generated by calculations using the investigated instruments. The results did not change with different oxygenation of the sample. The differences among methods were not significant when the HBOC concentration was 16.2 g/L. Higher concentrations of HBOC increased the difference between calculated and measured oxygen content; the i-STAT system demonstrated a greater deviation compared with the results of the other two instruments. Systemic oxygen uptake using the investigated instruments showed a high correlation with values based on LEXO2CON-K measurements (R = 0.97 for CO-Oximeter, R = 0.96 for Corning 170 blood gas analyzer, and R = 0.79 for i-STAT system). Systemic oxygen uptake values based on CO-Oximeter and Corning 170 blood gas analyzer data showed 75% accuracy; i-STAT system accuracy was 63% for control samples and 50% for samples after HBOC infusion.

The novel HemoCu plasma/low hemoglobin system accurately measures small concentrations of three different hemoglobin-based oxygen carriers in plasma: hemoglobin glutamer-200 (bovine) (Oxyglobin), hemoglobin glutamer-250 (bovine) (Hemopure), and hemoglobin-Raffimer (Hemolink)

The accuracy of the HemoCue Plasma/Low Hemoglobin System was validated in vitr. with low levels of hemoglobin-based oxygen carriers (HBOCs). Repeated measurements were performed on 50 samples of canine plasma, each mixed with three different HBOCs at varying small concentrations (a total of 150 samples), by using plasma samples without HBOCs as controls. Two technicians performed the measurements and randomly tested each sample 10 times. The results were analyzed for correlation, and analysis of variance was used to evaluate statistical significance, with a P value of </=0.05 considered significant. Hemoglobin concentrations determined with the bedside photometer were not significantly different from known values of hemoglobin concentration in the samples. There was no significant difference between values obtained by two independent observers for the same samples. This was true for all three tested HBOCs and for all tested concentrations. The mean bias of the measurement expressed as a percentage of sample concentration was 0.1% for hemoglobin glutamer-200 (bovine), 0.58% for hemoglobin glutamer-250 (bovine), and 0.19% for hemoglobin-raffimer. The mean error was <8% for all three HBOCs. Both intraobserver and interobserver reliabilities were high and statistically significant. The HemoCue Plasma/Low Hemoglobin System is a reliable instrument for detecting and measuring small concentrations of three different HBOCs in plasma.

IMPLICATIONS

This study evaluated a new bedside blood-measuring device for low levels and found that it rapidly measured low levels accurately for three blood substitutes.

Blood substitutes and oxygen therapeutics: an overview and current status

This review article discusses the development and implementation of a number of blood substitutes, including hemoglobin-based oxygen carriers (HBOCs) and perfluorocarbons. This review article will introduce the reader to blood substitutes by discussing an overview of an ideal blood substitute, the history of HBOCs and perfluorocarbons, strategies of oxygen carrying, side effects of HBOCs and perfluorocarbons, current clinical trials, and the future of blood substitutes.

Changes in circulating blood and plasma volume after hemoglobin-based oxygen carrier infusion and additional infusion of colloid solutions

The aim of this study was to investigate the changes in circulating blood volume (CBV) after infusions of Hemoglobin glutamer-200 (bovine; Hb-200) in combination with 6% hetastarch in an animal model of acute posthemorrhagic anemia. Fifteen rabbits with a mean body weight of 2.2 +/- 0.2 kg were studied. After determination of the circulating plasma volume (CPV) and CBV, one third of the CBV was withdrawn via an arterial catheter. An equal volume of Hb-200 was then infused in the 5 animals in study group 1. In the remaining 10 animals, the same volume of 6% hetastarch solution was infused. Fifteen minutes after completion of the infusion, an additional infusion of 6% hetastarch at a dose equal to one third of the baseline CBV was performed in study group 1 and the control group. In study group 2, equal volumes of Hb-200 were infused. CPV measurements were performed at baseline, after hemorrhage, 5 and 15 minutes after volume replacement, and 1 and 15 minutes after hypervolemic hemodilution using the Evans blue dye dilution technique. The mean baseline CPV value was 53.4 +/- 1.1 mL/kg. The mean CBV at baseline was 90.8 +/- 4.9 mL/kg. After one third of the CBV was withdrawn, no differences in CBV or CPV were observed between the three groups. Replacement of one third of the CBV with Hb-200 significantly increased the CPV (73.7 +/- 1.8 mL/kg) when compared with the baseline level (53.5 +/- 1.8 mL/kg; n = 5; P < 0.05). The difference between the groups was first observed 15 minutes after infusion. CPV was significantly higher in study group 1 (87.0 +/- 2.2 mL/kg) compared with the other groups (80.2 +/- 2.6 mL/kg in the control group and 79.5 +/- 3.6 mL/kg in study group 2). After a second transfusion, the differences between the groups became more prominent. Study group 2 demonstrated the highest CPV and CBV. The two study groups demonstrated a statistically significant increase in circulating volumes compared with the control group. The magnitude of this difference was lower than expected based on in vitro colloid osmotic pressure measurements.

Effects of hemoglobin glutamer-250 (bovine) (HBOC-201, Hemopure) on coagulation testing

Polymerized bovine hemoglobin is currently under investigation as an alternative to blood-banked human red blood cells. Because of the dark red hemolyzed appearance of hemoglobin-based oxygen carrier (HBOC)-201, we sought to describe the effects of HBOC-201 on coagulation analyzers that perform prothrombin times, activated partial thromboplastin times, fibrinogen, and antithrombin. Pooled normal plasma was combined with HBOC-201 to achieve plasma hemoglobin levels of 1.4, 2.6, 3.8, 4.8, and 6.2 g/dL. Results for each test using HBOC-201-prepared plasma were compared with results using saline-matched controls. Two consecutive absolute result differences of >10% between saline controls and HBOC-201 samples were used for determining interference in test accuracy by the concentration of HBOC-201. Mechanical detection methods (fibrometer, STA, CS-190) and the MDA-180 method were less affected by increasing levels of HBOC-201 than optical detection devices for all test parameters.

Polymerized bovine hemoglobin solution as a replacement for allogeneic red blood cell transfusion after cardiac surgery: results of a randomized, double-blind trial

BACKGROUND

Blood loss leading to reduced oxygen-carrying capacity is usually treated with red blood cell transfusions. This study examined the hypothesis that a hemoglobin-based oxygen-carrying solution can serve as an initial alternative to red blood cell transfusion.

METHODS

In a randomized, double-blind efficacy trial of HBOC-201, a total of 98 patients undergoing cardiac surgery and requiring transfusion were randomly assigned to receive either red blood cell units or HBOC-201 (Hemopure; Biopure Corporation, Cambridge, Mass) for the first three postoperative transfusions. Patients were monitored before and after transfusion, at discharge, and at 3 to 4 weeks after the operation for subsequent red blood cell use, hemodynamics, and clinical laboratory parameters.

RESULTS

The use of HBOC-201 eliminated the need for red blood cell transfusions in 34% of cases (95% confidence interval 21%-49%). Patients in the HBOC group received a mean of 1.72 subsequent units of red blood cells; those who received red blood cells only received a mean of 2.19 subsequent units (P =.05). Hematocrit values were transiently lower in the HBOC group but were similar in the two groups at discharge and follow-up. Oxygen extraction was greater in the HBOC group (P =.05). Mean increases in blood pressure were greater in the HBOC group, but not significantly so.

CONCLUSION

HBOC-201 may be an initial alternative to red blood cell transfusions for patients with moderate anemia after cardiac surgery. In a third of cases, HBOC-201 eliminated the need for red blood cell transfusion, although substantial doses were needed to produce this modest degree of blood conservation.