Fractured sternal wire causing a cardiac laceration

BACKGROUND

Hemopericardium is a serious complication that can occur after cardiac surgery. While most post-operative causes are due to inflammation and bleeding, patients with broken sternal wires and an unstable sternum may develop hemopericardium from penetrating trauma.

CASE PRESENTATION

We present the case of a 62-year-old male who underwent triple coronary bypass surgery and presented five months later with sudden anterior chest wall pain. Chest computed tomography revealed hemopericardium with an associated broken sternal wire that had penetrated into the pericardial space. The patient underwent a redo-sternotomy which revealed a 3.5 cm bleeding, jagged right ventricular laceration that correlated to the imaging findings of a fractured sternal wire projecting in the pericardial space. The laceration was repaired using interrupted 4 - 0 polypropylene sutures in horizontal mattress fashion between strips of bovine pericardium. The patient's recovery was uneventful and he was discharged on post-operative day four without complications.

CONCLUSION

Patients with broken sternal wires and an unstable sternum require careful evaluation and management as these may have potentially life-threatening complications if left untreated.

Renin Angiotensin Aldosterone System Antagonism in 2019 Novel Coronavirus Acute Lung Injury

It has been established that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses angiotensin-converting enzyme 2 (ACE2), a membrane-bound regulatory peptide, for host cell entry. Renin-angiotensin-aldosterone system (RAAS) inhibitors have been reported to increase ACE2 in type 2 pneumocyte pulmonary tissue. Controversy exists for the continuation of ACE inhibitors, angiotensin II receptor blockers, and mineralocorticoid receptor antagonists in the current pandemic. ACE2 serves as a regulatory enzyme in maintaining homeostasis between proinflammatory angiotensin II and anti-inflammatory angiotensin 1,7 peptides. Derangements in these peptides are associated with cardiovascular disease and are implicated in the progression of acute respiratory distress syndrome. Augmentation of the ACE2/Ang 1,7 axis represents a critical target in the supportive management of coronavirus disease 2019–associated lung disease. Observational data describing the use of RAAS inhibitors in the setting of SARS-CoV-2 have not borne signals of harm to date. However, equipoise persists, requiring an analysis of novel agents including recombinant human-ACE2 and existing RAAS inhibitors while balancing ongoing controversies associated with increased coronavirus infectivity and virulence.

Fixed and dilated pupils, not a contraindication for extracorporeal support: a case series

Extracorporeal membrane oxygenation is considered a relative contraindication for patients with severe neurological injury manifested by fixed and dilated pupils. The inability to provide adequate cardiopulmonary support while attempting to treat the underlying neurologic disease results in a fatal outcome. The impairment of cerebral perfusion, compounded by the underlying neurologic condition, results in signs of brainstem dysfunction often equated with a fatal prognosis. As a result, these patients are not considered to be candidates for initiation of extracorporeal membrane oxygenation. We present a case series of three patients with complex neurologic conditions with fixed and dilated pupils, who received extracorporeal membrane oxygenation. All three patients achieved a significant neurologic recovery. Two survived with a cerebral performance category scale of 1, and the third succumbed to multi-organ failure after achieving a Glasgow Coma Scale of 11T. The decision to initiate extracorporeal membrane oxygenation should be based upon the pathophysiology of the underlying neurologic condition and not solely upon isolated clinical findings. Extracorporeal membrane oxygenation use is normally reserved for patients with reversible underlying processes, and a neurologic exam with fixed and dilated pupils is often interpreted as an irreversible neurologic injury. The implementation and success of extracorporeal membrane oxygenation in this patient population require understanding of complex neurologic diseases, rapid recognition of neurocardiogenic shock, and expeditious initiation of cardiopulmonary support in carefully selected patients. The patients described demonstrate that fixed and dilated pupils are not a contraindication for extracorporeal support in select patients.

Extracorporeal Membrane Oxygenation as a Bridge to Initial Medical Therapy in a Patient With Decompensated Pulmonary Arterial Hypertension Presenting With Biventricular Failure

Extracorporeal membrane oxygenation (ECMO) can be used as a bridge to medical therapy in decompensated right heart failure due to pulmonary arterial hypertension (PAH). A middle-aged man with previously undiagnosed pulmonary hypertension was successfully bridged to intravenous prostanoid therapy with venoarterial ECMO support after presenting with cardiogenic shock and hypoxemic respiratory failure. Although the patient initially had biventricular failure, PAH was suspected due to underlying mixed connective tissue disease and disproportionate right ventricular dysfunction. On occasion, patients with PAH may present with biventricular failure. A high index of suspicion for PAH and serial reassessment of left ventricular function following correction of shock may demonstrate improvement in left ventricular function, allowing for initiation of pulmonary vasodilator therapy.

Early postoperative management after lung transplantation: Results of an international survey

INTRODUCTION

Little data exist regarding optimal therapeutic strategies postoperatively after lung transplant (LTx). Current practice patterns rely on expert opinion and institutional experience resulting in nonuniform postoperative care. To better define current practice patterns, an international survey of LTx clinicians was conducted.

METHODS

A 30-question survey was sent to transplant clinicians via email to the International Society of Heart and Lung Transplantation open forum mailing list and directly to the chief transplant surgeon and pulmonologist of all LTx centers in the United States.

RESULTS

Fifty-two clinicians representing 10 countries responded to the survey. Sedatives use patterns included: opiates + propofol (57.2%), opiates + dexmedetomidine (18.4%), opiates + intermittent benzodiazepines (14.3%), opiates + continuous benzodiazepines (8.2%), and opiates alone (2%). About 40.4% reported no formal sedation scale was followed and 13.5% of programs had no formal policy on sedation and analgesia. A lung protective strategy was commonly employed, with 13.8%, 51.3%, and 35.9% of respondents using tidal volumes of <6 mL/kg ideal body weight (IBW), 6 mL/kg IBW, and 8 mL/kg IBW, respectively.

CONCLUSION

Practice patterns in the early postoperative care of lung transplant recipients differ considerably among centers. Many of the reported practices do not conform to consensus guidelines on management of critically ill patients.

Hemothorax following lung transplantation: incidence, risk factors, and effect on morbidity and mortality

Background: Hemothorax after lung transplantation may result in increased post-operative morbidity and mortality. Risk factors for developing hemothorax and the outcomes of patients who develop hemothorax have not been well studied. Methods: A retrospective chart review was performed on all patients who underwent lung transplantation at a single center between March 2009 and July 2014. Comparison was made between patients with and without hemothorax post-transplant. Results: There were 132 lung transplantations performed during the study period. Hemothorax was a complication in 17 (12.9 %) patients, occurring an average of 9 days after transplant. No difference was found between the hemothorax and non-hemothorax groups with respect to age, preoperative anticoagulation, lung allocation score, prior thoracotomy, coagulation profile, use of cardiopulmonary bypass, ischemic time, or postoperative P/F ratio. There was a trend towards a higher incidence of hemothorax in patients with underlying sarcoidosis and re-transplantation (p = 0.13 and 0.17, respectively). Hemothorax developed early (<48 h post-operatively) in 5 patients and presented in a delayed manner (≥48 h post-operatively) in 12 patients. Delayed hemothorax occurred primarily in the setting of anticoagulation (10 out of 12 patients). The hemothorax group had decreased ventilator-free days (p = 0.006), increased ICU length of stay (p = 0.01) and increased hospital length of stay (p = 0.005). Hemothorax was also associated with reduced 90-day survival (p = 0.001), but similar 1, 3, and 5-year survival (p = 0.63, p = 0.30, and p = 0.25), respectively). Conclusion: The development of hemothorax is associated with increased morbidity and decreased short-term survival. Hemothorax may present either within the first 48 h after surgery or in a delayed fashion, most commonly in the setting of anticoagulation.

Hemothorax following lung transplantation: incidence, risk factors, and effect on morbidity and mortality

BACKGROUND

Hemothorax after lung transplantation may result in increased post-operative morbidity and mortality. Risk factors for developing hemothorax and the outcomes of patients who develop hemothorax have not been well studied.

METHODS

A retrospective chart review was performed on all patients who underwent lung transplantation at a single center between March 2009 and July 2014. Comparison was made between patients with and without hemothorax post-transplant.

RESULTS

There were 132 lung transplantations performed during the study period. Hemothorax was a complication in 17 (12.9 %) patients, occurring an average of 9 days after transplant. No difference was found between the hemothorax and non-hemothorax groups with respect to age, preoperative anticoagulation, lung allocation score, prior thoracotomy, coagulation profile, use of cardiopulmonary bypass, ischemic time, or postoperative P/F ratio. There was a trend towards a higher incidence of hemothorax in patients with underlying sarcoidosis and re-transplantation (p = 0.13 and 0.17, respectively). Hemothorax developed early (<48 h post-operatively) in 5 patients and presented in a delayed manner (≥48 h post-operatively) in 12 patients. Delayed hemothorax occurred primarily in the setting of anticoagulation (10 out of 12 patients). The hemothorax group had decreased ventilator-free days (p = 0.006), increased ICU length of stay (p = 0.01) and increased hospital length of stay (p = 0.005). Hemothorax was also associated with reduced 90-day survival (p = 0.001), but similar 1, 3, and 5-year survival (p = 0.63, p = 0.30, and p = 0.25), respectively).

CONCLUSION

The development of hemothorax is associated with increased morbidity and decreased short-term survival. Hemothorax may present either within the first 48 h after surgery or in a delayed fashion, most commonly in the setting of anticoagulation.

Cardiothoracic surgical emergencies in the intensive care unit

Patients with cardiothoracic surgical emergencies are frequently admitted to the ICU, either prior to operative intervention or after surgery. Recognition and appropriate timing of operative intervention are key factors in improving outcomes. A collaborative team approach with the cardiothoracic service is imperative in managing this patient population.

Deficient leucocyte antisedimentation is related to post-stroke infections and outcome

BACKGROUND

Patients with stroke are more susceptible to infections, suggesting possible deficiencies of early immune responses, particularly of leucocytes.

AIMS

To serially examine leucocyte antisedimentation rate (LAR), a simple test to detect activation of leucocytes, and correlate it with S100beta, procalcitonin and outcome in patients with acute ischaemic events.

METHODS

Venous blood samples were taken from 61 healthy volunteers and 49 patients with acute ischaemic events (acute ischaemic stroke (AIS), n = 38; transient ischaemic attack (TIA), n = 11) within 6 hours, at 24 and 72 hours after onset of symptoms.

RESULTS

LAR was significantly higher in acute ischaemic events compared to controls within 6 hours after onset of stroke regardless of post-stroke infections. In addition, the increase of LAR was delayed and attenuated in TIA in contrast to AIS. A deficiency in early increase of LAR was associated with post-stroke infections and a poor outcome, measured by the Glasgow Outcome Scale in AIS. There was a positive correlation between LAR and S100beta at 72 hours after the onset of ischaemic stroke. Increased levels of S100beta at 24 and 72 hours after stroke were associated with poor outcome.

CONCLUSIONS

An early activation of leucocytes indicated by an increase of LAR is characteristic of acute ischaemic cerebrovascular events. A delayed and ameliorated leucocyte activation represented by LAR is characteristic of TIA in contrast to stroke. Deficient early activation predisposes to post-stroke infections related to poor outcome. In addition, the extent of tissue injury correlates with the magnitude of innate immune responses.

Rigid sternal fixation improves postoperative recovery

Introduction:

During the past five years, ridged sternal fixation has been utilized for sternal closure after cardiac surgery. It is known that this procedure provides better sternal stability; however, its contribution to patient recovery has not been investigated.

Methods:

Retrospective chart review was conducted for patients who underwent CABG and/or valve surgery in our institution between 2009 and 2010. Preoperative, perioperative, and follow-up data of patients with ridgid fixation (group R, n=89) were collected and compared with those patients with conventional sternal closure (group C, n=133). The decision regarding the sternal closure method was based on the surgeon’s preferences. Univariate followed by multivariate analyses were performed to evaluate the dominant factor of sternal lock usage and to evaluate postoperative recoveries. The factors included in the analyses were; age, sex, coronary risk factors, urgency of surgery, ejection fraction, coronary anatomy, preoperative stroke, renal function, and preoperative presence of heart failure. All statistical analyses were performed by JMP software.

Results:

Group R was younger (62 ± 9 in group R vs 69 ± 11 in group C, p<0.0001) than group C, more male dominant (61% vs 49%, p=0.0452), had a lower percentage of patients undergoing redo-surgery (2.2% vs 9.0%, p<0.0418), was more likely to be used in isolated coronary artery bypass grafting (71% vs 46%, p=0.0002), more often to be used for large patient (body mass index, BMI greater than 30) (58% vs 37%. P=0.0045), and patients were more likely to have a low EuroSCORE (2.6 ± 2.3 vs 4.4 ± 2.7). Intubation time (13 ± 20 hours vs 39 ± 97 hours, p=0.0030), ICU stay (58 ± 40 hours vs 99 ± 119 hours, p=0.0003), and postoperative length of stay (7.0 ± 3.7 days vs 8.4 ± 4.7 days, p<0.0141) were significantly shorter in group R than group C. Multivariate analyses showed ridged sternal fixation was the most dominant factor affecting intubation time and ICU stay.

Conclusion:

Rigid sternal fixation systems were more frequently applied to low risk young male patients. Among these selected patients, ridgid sternal fixation can contribute to early patient recovery.

Validation of a clinical assessment tool for spinal anaesthesia

BACKGROUND

There is a need for a procedure-specific means of assessment of clinical performance in anaesthesia. The aim of this study was to devise a tool for assessing the performance of spinal anaesthesia, which has both content and construct validity.

METHODS

The clinical assessment tool was generated using a focus group discussion of practicing anaesthetists. The tool comprised three components: a checklist of 11 pre-defined errors, two time intervals and a six-item global rating scale (GRS). Thirty-one anaesthetists at three different levels of experience underwent testing using the clinical assessment tool: novice (n=10), intermediate (n=10) and expert (n=11).

RESULTS

The error checklist and GRS scores but not the time intervals were significantly different between the three groups (P<0.005).

CONCLUSION

The error checklist and GRS form the basis for a procedure-specific assessment tool for spinal anaesthesia.

Direct effects of chemoradiotherapy following esophagectomy

BACKGROUND

Esophageal cancer is a major cause of morbidity and mortality, but despite continuing research, few effective therapies have been identified. In recent years, surgical resection following chemoradiotherapy has been associated with improved survival in several clinical models.

AIM

In a prospective, observational study, we evaluated the direct effects of chemoradiotherapy on postoperative mortality, morbidity, and inflammatory response in patients following esophagectomy.

METHODS

The study cohort was divided into two groups: the first group received preoperative chemoradiotherapy, while the second group had surgical intervention without prior treatment. Nutritional status was evaluated for the members of both patient groups at various time points.

RESULTS

Preoperative chemoradiotherapy did not influence morbidity or organ function, and the postoperative inflammatory response did not show immunosuppressive side effects directly after surgery.

CONCLUSION

Preoperative chemoradiotherapy does not improve postoperative organ function, inflammatory response or nutritional status in the patients. These findings may help to improve outcome in patients with esophageal cancer in the future.

Effect of glutamine in patients with esophagus resection

Glutamine is the most abundant amino-acid in the extra- and intracellular compartments of the human body, which accounts for over 50% of its free amino-acid content. Utilization of glutamine peptides is explicitly useful, resulting in a decrease in the number of postoperative infectious complications, period of hospitalization, and therapeutic costs. This article aims to study the effects of glutamine on systemic inflammatory response, morbidity, and mortality after esophagectomy. A prospective, randomized, double-blind, and controlled trial was used. Following sealed-envelope block randomization, the patients were divided into two groups. Members of the glutamine group (group G) received glutamine (Dipeptiven, Fresenius) as continuous infusion for 6 hours at 0.5 g/kg for 3 days prior to, and 7 days following surgery; while patients of the control group were given placebo. We examined 30 patients in group G, and 25 patients as controls. In both patient groups, the levels of total protein, albumin, pre-albumin, retinol binding protein, transferrin, transferring-saturation, C-reactive protein, procalcitonin, lymphocte, Interleukin-6, Interleukin-8, tumor necrosis factor alpha, and serum lactate were determined prior to surgery (t(0)), directly after surgery (t(u)), following surgery on day 1 (t(1)), day 2 (t(2)), and day 7 (t(7)). For statistical analysis Mann-Whitney U test and chi-square test were used. There was no significant difference between the two groups regarding age, male/female ratio, and SAPS II scores. Intensive care unit morbidity and mortality was similar in both groups (group G: 24 survivors/6 nonsurvivors;

CONTROL

17 survivors/8 nonsurvivors; P= 0.607). Daily Multiple Organ Dysfunction Score did not differ significantly between the two groups. The observed inflammatory markers followed the pattern we described without significant difference. Based on our study, the glutamine supplementation that we used had no influence on morbidity, mortality, or postoperative inflammatory response after esophagectomy.

Arterial thermodilution in burn patients suggests a more rapid fluid administration during early resuscitation

BACKGROUND

A number of target points have been used for fluid replacement in severely burned patients. The aim of our prospective randomized study was to compare the effect of two different types of fluid resuscitation regimes on the multiple organ dysfunction score (MODS) and central venous oxygen saturation (ScvO(2)) in the first 3 days after injury.

METHODS

Twenty-four patients admitted to the critical care unit of a university hospital with the presence of burn injury affecting more than 15% of the body surface area and in-hospital fluid resuscitation started within 3 h after burn injury were included. Patients were randomized into two groups. Fluid resuscitation was guided by the hourly urine output (HUO Group, n=12) or by the intrathoracic blood volume index (ITBVI Group, n=12). Invasive transpulmonary hemodynamic measurements utilizing pulse contour analysis with a single dilution technique and continuous ScvO(2) measurements were performed in both groups.

RESULTS

The mean ScvO(2) was significantly lower in the HUO Group than in the ITBVI Group (P=0.024) for the first 24 h. MODS was significantly higher in the HUO Group than in the ITBVI group 48 h (P=0.024) and 72 h after injury (P=0.014). The two main outcome parameters, i.e., MODS calculated at 48 and 72 h after injury and ScvO(2) were negatively correlated on day 1 (r=-0.684, P=0.004, r=-0.677, P=0.003). There were no statistical differences in clinical outcome parameters.

CONCLUSION

Our data suggest that ITBVI may be a better target parameter than HOU in the fluid resuscitation of severely burned patients after injury.

Short-term effects of N-acetylcysteine and ischemic preconditioning in a canine model of hepatic ischemia-reperfusion injury

AIMS

We evaluated the possibility that repeated ischemic preconditioning or N-acetylcysteine (NAC) could prevent ischemia-reperfusion injury as determined by indocyanine green plasma disappearance rate (ICG-PDR) or has favorable hemodynamic effects during reperfusion in an in vivo canine liver model.

METHODS

Under general anesthesia, 3 groups of mongrel dogs (n = 5 per group) were subjected to (1) 60-min hepatic ischemia, (2) same ischemia preceded by intravenous administration of 150 mg kg(-1) NAC, and (3) three episodes of IPC (10-min ischemia followed by 10-min reperfusion) prior to same ischemia. Hepatic reperfusion was maintained for a further 180 min, with hemodynamic and hepatic function parameters monitored throughout.

RESULTS

Plasma disappearance rate of indocyanine green and serum levels of aspartate transferase and alanine transferase showed no significant differences between groups. Although liver injury was obvious, reflected by hemodynamic, blood gas, and liver function tests, NAC and IPC failed to prevent decay in hepatic function in this canine model.

CONCLUSION

The results do not support the hypothesis that short-term use of NAC and IPC is beneficial in hepatic surgery.

Low hematocrit per blood viscosity ratio as a mortality risk factor in coronary heart disease

Increased blood viscosity has not been associated with mortality risk in coronary heart disease (CHD). We aimed to investigate the predictive power of hematocrit per blood viscosity (Hct/BV) ratio as a marker of rheological oxygen carrying capacity of the blood to assess mortality risk of CHD. Elective coronary angiography was performed and CHD was proved in 109 patients in 1996 and 1997. In 78 cases (72%) complete follow up information was obtained in February 2006. During the follow up time (mean 8.9 years) 10 patients died due to cardiac cause (group C). Two patients died due to non-cardiac cause and 66 were still alive at the end of the follow up period (group NC, n=68). Mean hematocrit per blood viscosity (Hct/BV) ratio was significantly lower in group C comparing to NC (87+/-5; 93+/-9 Pa(-1)s(-1), SD, respectively, p=0.022). Other factors (body mass index, serum cholesterol, fibrinogen, hematocrit, plasma and blood viscosity, cardiac index, left ventricular ejection fraction) provided no statistical differences. Kaplan-Meier survival analysis showed only the impact of fibrinogen and Hct/BV ratio on cardiac mortality (p=0.029 and 0.009, respectively). Receiver operating characteristic curves proved only Hct/BV ratio to be able to differentiate between groups (area under curve: 0.716, p=0.028). Hct/BV ratio showed significant negative correlation with the frequency of hospital admissions (r=-0.377, p=0.03). Low Hct/BV ratio can be regarded as a risk factor of cardiac death in CHD.

Pre-operative coronary revascularization: an optimal therapy for high-risk vascular surgery patients?

Cardiac complications are the leading cause of peri-operative morbidity and mortality of patients undergoing vascular surgery. This high incidence of cardiac complications is related to the presence of underlying coronary artery disease. The optimal treatment strategy for these high-risk patients, including the use of pre-operative coronary revascularization for the purpose of improving peri-operative and long-term cardiac outcomes, has been controversial for several decades. Recently, the results of the Coronary Artery Revascularization Prophylaxis (CARP) trial showed that in the short term there is no reduction in the number of post-operative myocardial infarctions, deaths or length of stay in the hospital, or in long-term outcomes in patients who underwent pre-operative coronary revascularization compared with patients who received optimized medical therapy. In this review, we summarize the role of pre-operative revascularization before elective vascular surgery using current evidence from the CARP trial and of those from published studies.

Cardiac risk reduction in non-cardiac surgery: the role of anaesthesia and monitoring techniques

Cardiac complications are the major cause of perioperative morbidity and mortality of patients undergoing non-cardiac surgery. This is related to the frequent presence of underlying coronary artery disease. In the last few decades, attention has focused on preoperative cardiac risk assessment that may help to identify patients at increased cardiac risk for whom cardioprotective medication and, when indicated, coronary revascularization may improve perioperative outcome. On the other hand, less attention was given to the role of anaesthesia and monitoring techniques in the cardiac risk management of high-risk patients undergoing non-cardiac surgery. The aim of this review was to summarize the current evidence from published studies on the effect of the type of anaesthesia and monitoring techniques on perioperative cardiac outcome in non-cardiac surgery.

Sedimentation characteristics of leucocytes can predict bacteraemia in critical care patients

BACKGROUND

Early detection of blood stream infection can be lifesaving, but the results of blood cultures are not usually available before 24 hours after blood sampling. An earlier indication would lead to the initiation of immediate and adequate antibiotic treatment with obvious advantages for the patient.

OBJECTIVE

To evaluate the ability of leucocyte count, serum procalcitonin (PCT) concentration, erythrocyte sedimentation rate (ESR), and leucocyte antisedimentation rate (LAR) in predicting the blood culture results in critical care patients.

METHODS

39 consecutive patients with their first febrile episode were investigated prospectively. LAR was determined as the percentage of leucocytes crossing the midline of a blood column upward during one hour of gravity sedimentation. The relevance of the different variables was estimated by likelihood ratio tests and area under receiver operating characteristic curves (AUC).

RESULTS

23 patients had positive blood culture results and 16 negative. LAR was significantly higher in bacteraemic patients than in non-bacteraemic patients (p = 0.001), but leucocyte count, ESR and PCT level failed to show significant differences. Leucocyte count, PCT, and ESR yielded low discriminative values with the AUCs of 0.66, 0.64, and 0.52, respectively. LAR provided a likelihood ratio of 3.6 and an AUC of 0.80 (95% confidence interval, 0.64 to 0.95) (p = 0.002).

CONCLUSIONS

The simple LAR test can predict blood culture results and support urgent treatment decisions in critical care patients in their first febrile episode.

Gender differences in hemorheological parameters of coronary artery disease patients

Plasma fibrinogen concentration, plasma and whole blood viscosity (WBV) are independent risk factors of coronary artery disease (CAD). Fibrinogen seems to be a relatively stronger risk factor for women than for men, but men are more endangered by higher hematocrit (Hct) and WBV than women are. We have previously reported that a theoretically optimal Hct value can be determined using Hct/WBV ratio in healthy subjects, hyperlipidemic and Raynaud's disease patients. Our aim was to examine whether Hct/WBV ratio is differently correlated with Hct in men and women with proven CAD. In a retrospective study we analysed the hemorheological data of 162 CAD outpatients (107 men and 55 women). Coronary angiography, echocardiography and impedance cardiography were performed. Hemorheological parameters (Hct, fibrinogen level, plasma viscosity, WBV), blood picture, serum lipid concentrations were determined and Hct/WBV ratio was calculated. Mean ages of male and female patients were similar (54.9 and 55.4 years, respectively), but men had significantly higher coronary angiography score than women. Mean left ventricular ejection fraction, stroke volume index and cardiac index showed no significant differences in men and women. Similarly, lipid concentrations, fibrinogen levels and plasma viscosities demonstrated no statistical differences. However, Hct, WBV and Hct/WBV ratios were significantly higher in male than in female patients (p < 0.00001; p < 0.00001 and p < 0.005, respectively). The most striking gender difference was found in the correlation between Hct/WBV ratio and cardiac index. Men older than 56 years showed negative, women positive correlation (r = -0.485, p = 0.01; r = 0.468, p = 0.006, respectively). This study demonstrates that Hct/WBV ratio as a rheological oxygen carrying capacity parameter is positively correlated with the cardiac index as it can be expected. However, the correlation is negative in elder men indicating an unhealthy relation between hemodynamic and hemorheologic parameters.

Erythrocyte transport efficacy of human blood: a rheological point of view

BACKGROUND

Large-scale epidemiological studies have demonstrated that both anaemia and polycytaemia are independent cardiovascular risk factors. This was substantiated by the Framingham study, which demonstrated a U-shaped relation between haemoglobin concentration and mortality. It was previously noted that delineating the corresponding haematocrit/blood viscosity ratios in the function of haematocrit provided a distribution of an inverted U-shaped curve. The peak appeared physiologically important because it denotes a healthy balance between a relatively high oxygen binding capacity and a moderately low blood viscosity. It was the aim of this study to examine the mathematical relationship between the haematocrit and haematocrit/blood viscosity ratio.

MATERIALS AND METHODS

In a retrospective study, the haemorheological data of 32 healthy controls, 52 outpatients with hyperlipidaemia and 120 outpatients with Raynaud's disease were analyzed. Whole blood viscosity was measured with Hevimet 40 capillary viscometer at 37.0 degrees C and at shear rates of 10 s(-1), 90 s(-1) and 200 s(-1).

RESULTS

Haematocrit/blood viscosity ratios in the function of haematocrit values showed a Gaussian association in the healthy subjects, hyperlipidaemic and Raynaud's disease outpatient groups. Peak values (i.e. the rheologically optimal haematocrit) were shear-rate and group dependent and were found at 44.3%, 43.5% and 38.3% in controls, hyperlipidaemic and Raynaud's disease patients, respectively, at a shear rate of 90 s(-1).

CONCLUSIONS

This is one of the first reports in which a theoretically optimal haematocrit value was determined using the haematocrit/blood viscosity ratio. Further studies are needed to examine the potential clinical usefulness of this approach.

Characteristics of light and heavy polymorphonuclear leukocytes

Whole blood gravity sedimentation technique can be modified for studying leukocyte sedimentation properties. Previously, we demonstrated that the displacement rate of leukocytes was associated with activation of leukocytes during traditional gravity sedimentation of the whole blood. The plasma flow as well as the difference between the specific gravity of leukocytes and plasma propel the leukocytes upward in the sedimentation tube while the erythrocyte aggregates are descending. The leukocyte ascension rate can be described as the increment of leukocyte concentration in the upper half section of the blood column after one-hour sedimentation. The aim of the present study was to characterize the ascending and non-ascending leukocytes using a flow cytometric technique. Venous blood samples were taken from 8 healthy controls and 8 septic patients after major thoracic or abdominal surgical procedures. The upper and lower halves sections of venous blood column were separately removed from the sedimentation tube after one hour gravity sedimentation. Using flow cytometry, the leukocyte subsets were identified by their CD45 density and side scatter parameters followed by characterization of their cellular size and cytoplasmic granularity. The size indices of septic patients' ascending polymorphonuclear leukocytes (PMNs) were significantly lower than that of the non-ascending ones (253 +/- 22 versus 387 +/- 12 (SEM), p < 0.002) or the ascending PMN fraction taken from healthy individuals (382 +/- 28, p < 0.005). Septic patients' ascending PMNs presented significantly lower cytoplasmic granularity indices compared to non-ascending (447 +/- 23 versus 538 +/- 18, p < 0.05) or healthy ascending PMNs (539 +/- 20, p < 0.05). The cellular size and cytoplasmic granularity indices of heavy and light monocytes as well as lymphocytes were similar in both groups. It can be assumed that venous blood samples of septic patients contain significantly smaller PMNs with less cytoplasmic granularity than healthy control cells.

Hemorheology and hypertension: not "chicken or egg" but two chickens from similar eggs

A number of clinical studies have demonstrated significant positive correlation between the severity of arterial hypertension (AHT) and whole blood viscosity. Red blood cell aggregation has also been associated with AHT especially in the severe form of the disease. The main possible cause of increased red blood cell aggregation is fibrinogen which can be found in a significantly higher concentration in patients with AHT than in healthy controls. On the other hand, blood pressure reduction with angiotensin-converting-enzyme inhibitors, calcium-channel-blocking agents, beta or alpha-receptor blocking drugs leads to a significant improvement of blood rheology. It can be presumed that abnormal hemorheology and AHT are not directly linked but they share the same inductive genetic and/or environmental factors like obesity, chronic mental stress, physical inactivity and cigarette smoking. Regarding this hypothesis, the appropriate question is not whether hemorheological factors are causes or results of AHT but what their common origins are. Further studies are needed to clarify this hypothetical link between hemorheology and AHT.

Leukocyte flotation during gravity sedimentation of the whole blood

The original Westergren blood sedimentation technique was modified to assess leukocyte sedimentation properties. The relative change of leukocyte and erythrocyte counts was measured in the upper half section of blood column in vertically positioned sedimentation tubes in 10-minute-intervals for 60 minutes. During the first 20 minutes of gravity sedimentation, the leukocytes taken from critically ill patients showed upward flotation, however, healthy individuals' leukocytes demonstrated slight sedimentation. The upward flotation rate of leukocytes seemed less dependent on erythrocyte sedimentation during the first 15 minutes of sedimentation time than after it. Based on this observation, the sedimentation properties of leukocytes were characterized by the leukocyte antisedimentation rate taken at the 15th minute of sedimentation time (LAR15). Erythrocyte aggregability index, plasma fibrinogen concentration and native leukocyte count did not correlate to LAR15 in healthy volunteers (n = 25). However, LAR15 was correlated to leukocyte adherence (p < 0.01), to whole blood viscosity (p < 0.05), to hematocrit (p < 0.05) and to the conventional erythrocyte sedimentation rate (p < 0.05).

The effect of RheothRx Injection on the hemorheological parameters in patients with acute myocardial infarction

This study evaluated the hemorheological effects of a nonionic block copolymer surfactant, RheothRx Injection, on the hemorheological parameters in patients with acute myocardial infarction (AMI). For the in vitro study blood from 24 patients admitted with chest pains (mean age: 49 +/- 11 yrs) was sampled after admission and in AMI cases (15 patients, mean age: 53 +/- 13 yrs) a second sample was collected 48 hours later. Different concentrations of RheothRx were added (0.25, 0.5, 1, 2 and 5 mg/ml) and the blood was tested for RBC aggregation via our computerized Myrenne Aggregometer (at Hct = 40%). Besides other routine laboratory parameters, fibrinogen levels were measured. In a substudy for CORE Trial, the hemorheological effects of RheothRx infusion was studied. Seven patients (mean age: 63 +/- 13 yrs) admitted with AMI and randomized for CORE Trial were studied. The samples were collected after admission, at 12, 24, 48 hours, and at day 8 and 35. In vitro we found a significant (p < 0.05 or better) concentration-related decrease of RBC aggregation from 0.5 mg/ml drug concentration in the admission (both groups) and in the 48 hour (AMI) samples, in AMI patients with a mean decrease of 7 and 5% at 0.5 mg/ml, 13 and 8% at 1 mg/ml, 22 and 19% at 2 mg/ml and 39 and 33% at 5 mg/ml plasma concentration of the drug. In the CORE Trial patients hemorheological parameters (plasma and whole blood viscosity, RBC aggregation and fibrinogen level) decreased during and after the administration of RheothRx, but after 2-8 days their values returned to the baseline level. These findings indicate that this agent can significantly reduce RBC aggregation and other hemorheological parameters, and thus suggest its potential usefulness in clinical states associated with increased RBC aggregation.

A new simplified assay for evaluation of motile activity of human polymorphonuclear leucocytes

We studied the adaptation of a filtration instrument to an assay for cell migration experiments. The commercially available Nuclepore filter holders were modified so that isolated human polymorphonuclear leucocytes (PMNs) were allowed to penetrate a porous filter membrane and to enter a compartment under the membrane. The total number of PMNs which had passed the pores during an hour of incubation could be counted. In this way we carried out experiments using Shigella sonnei lipopolysaccharide and dilutions of E. coli culture supernatant as chemoattractants for healthy human PMNs. These studies showed that the method can distinguish between random and directed movements of PMNs and it is sensitive to the concentrations of chemoattractant. Furthermore, the data obtained using PMNs from the same subject on different days seem to be comparable.

Initial filtration rate and initial clogging in the Hemorheometre

The role of different factors contributing to red cell filterability in the Hemorheometre has been investigated. Although the original method uses a small volume of suspension to determine red cell filterability, the present experiments showed that the results obtained are still significantly affected by filter clogging. Consequently a change in filterability could be due to a change in filter clogging possibly by residual leucocytes. An adaptation of filter chamber and filling method is described, resulting in a simpler and faster measuring procedure. The inaccuracy in measuring low haematocrits contributes significantly to experimental errors. Therefore a definition of red cell filterability based on the red cell count (instead of haematocrit) of the suspension is suggested.

Serotonin and the flow properties of blood

The effects of serotonin and its pharmacological antagonists on the physical flow properties of the blood have been studied far less than their effects on blood vessels, although they may be equally important. Indirect evidence suggests that in pathological circumstances serotonin may locally increase whole blood viscosity, particularly at low shear rates, decrease red cell deformability and increase the adhesiveness of white cells. Although the viscosity of the plasma alone is not affected, the rheological effects of serotonin on blood cells is probably dependent on the presence of platelets. These mechanisms may have a systemic effect in some forms of hypertension as well as in situations of local ischaemia such as Raynaud's phenomenon, atherosclerotic pregangrene of the leg or acute myocardial infarction. Specific serotonergic-antagonists, administered either orally or intravenously, normalize the increased whole blood viscosity and decreased blood filterability found in essential hypertension, following myocardial infarction and in severe leg ischaemia. The effect on red cell deformability is usually greatest when the cells are resuspended in platelet rich plasma. Ketanserin given intravenously for seven days to patients with very severe leg ischaemia, significantly improves whole blood viscosity, increases red cell transit time and most dramatically decreases pore clogging. This last effect was at least partly due to a change in the physical properties, but not the number of the white cells. The reported beneficial clinical effects of such an antagonist in various forms of peripheral ischaemia and essential hypertension may well be due, at least partly, to the normalization of the rheological properties of the blood.