The pathophysiology of shock

Centhaquine Restores Renal Blood Flow and Protects Tissue Damage After Hemorrhagic Shock and Renal Ischemia

Background: Centhaquine (CQ) (Lyfaquin®) is in late stage clinical development as a safe and effective first-in-class resuscitative agent for hemorrhagic shock patients (NCT02408731, NCT04056065, and NCT04045327). Acute kidney injury (AKI) is known to be associated with hemorrhagic shock. Hence, effect of CQ on protection of kidneys from damage due to hemorrhagic shock was investigated. Methods: To assess effect of CQ on AKI in shock, we created a rat model with hemorrhagic shock and AKI. Renal arteries were clamped and de-clamped to induce AKI like ischemia/reperfusion model and hemorrhage was carried out by withdrawing blood for 30 min. Rats were resuscitated with CQ (0.02 mg/kg) for 10 min. MAP, heart rate (HR), and renal blood flow (RBF) were monitored for 120 min. Results: CQ produced a significant improvement in RBF compared to vehicle (p< 0.003) even though MAP and HR was similar in CQ and vehicle groups. Blood lactate level was lower (p = 0.0064) in CQ than vehicle at 120 min post-resuscitation. Histopathological analysis of tissues indicated greater renal damage in vehicle than CQ. Western blots showed higher HIF-1α (p = 0.0152) and lower NGAL (p = 0.01626) levels in CQ vs vehicle. Immunofluorescence in the kidney cortex and medulla showed significantly higher (p< 0.045) expression of HIF-1α and lower expression of Bax (p< 0.044) in CQ. Expression of PHD 3 (p< 0.0001) was higher, while the expression of Cytochrome C (p = 0.01429) was lower in the cortex of CQ than vehicle. Conclusion: Results show CQ (Lyfaquin®) increased renal blood flow, augmented hypoxia response, decreased tissue damage and apoptosis following hemorrhagic shock induced AKI, and may be explored to prevent/treat AKI. Translational Statement: Centhaquine (CQ) is safe for human use and currently in late stage clinical development as a first-in-class resuscitative agent to treat hemorrhagic shock. In the current study, we have explored a novel role of CQ in protection from hemorrhagic shock induced AKI, indicating its potential to treat/prevent AKI.

Coadministration of a Na+-H+ exchange inhibitor and sodium bicarbonate for the treatment of asphyxia-induced cardiac arrest in piglets

BACKGROUND

The present study tested the hypothesis that addition of an inhibitor of Na(+)/H(+) exchanger (NHE1) to sodium bicarbonate might improve the response to base therapy from prolonged asphyxial cardiac arrest in piglets.

METHODS

Asphyxial cardiac arrest was induced by endotracheal tube clamping. Animals were randomly assigned to four study groups: (i) vehicle control, (ii) administration of sabiporide (NHE1 inhibitor), (iii) administration of sodium bicarbonate, and (iv) administration of sabiporide and sodium bicarbonate.

RESULTS

Administration of sodium bicarbonate alone did not affect survival, hemodynamic measures, and regional blood flow to critical tissues such as brain, heart, kidney, liver, and spleen. In contrast, sabiporide given alone or combined with sodium bicarbonate improved these. Furthermore, treatment with sabiporide reduced accumulation of neutrophils, reduced cytokine production in the lung, and reduced plasma levels of cardiac troponin-I, alanine aminotransferase, aspartate aminotransferase, and urea. In addition, the combined use of sabiporide and sodium bicarbonate had more profound reduction in interleukin (IL)-6 and IL-10, compared to sabiporide alone.

CONCLUSION

These results suggest that addition of sabiporide to the administration of sodium bicarbonate might improve hemodynamic response and dampen the inflammatory cascade noted with cardiac arrest, and therefore being an attractive option in the treatment of cardiac arrest.

Protective effects of NHE1 inhibition with sabiporide in an experimental model of asphyxia-induced cardiac arrest in piglets

The present study investigated the protective effects of a novel NHE1 selective inhibitor, sabiporide, in a porcine model of asphyxia-induced cardiac arrest. Asphyxial cardiac arrest was induced by endotracheal tube clamping (ETC). The animals remained untreated for 3 min after loss of aortic pulsations (LOAP), and followed by chest compression and defibrillation. Sixteen of eighteen pigs had return of spontaneous circulation (ROSC), and were randomly assigned to two study groups. Group 1: vehicle control. Group 2: 3mg/kg sabiporide was given at 15 min after ROSC. Post-arrest myocardial dysfunction was present in both groups, and progressed over hours. Animals treated with sabiporide had less wall motion abnormality and higher left ventricular ejection fraction than control animals (33% in control group vs. 47% in sabiporide group). Sabopiride treatment also significantly improved post-arrest arterial blood pressure by 25% and cardiac stroke volume by 44%, and improved mixed-venous blood oxygen saturation by 38% and oxygen delivery by 118%. Furthermore, compared to the control group, the sabiporide group also had higher blood flows in the brain, heart, kidney, liver and spleen at 30 min after ROSC. There was no significant blood flow difference in distal ileum mucosa between control and sabiporide groups. In addition, sabiporide treatment significantly reduced cardiac myeloperoxidase (MPO) activity by 53% and cardiac troponin I by 51%, and reduced the plasma level of TNF-α by 52% and IL-6 by 41%. This study shows that post-arrest pharmacological conditioning with sabiporide affords protection from whole body ischemia-reperfusion injury in this model of asphyxia-induced cardiac arrest and resuscitation.

Near-infrared spectroscopy as a hemodynamic monitor in critical illness

BACKGROUND

Near-infrared spectroscopy has moved from a research tool to a widely used clinical monitor in the critically ill pediatric patient over the last decade. The physiological and clinical evidence supporting this technology in practice is reviewed here.

METHODOLOGY

A search of MEDLINE and PubMed was conducted to find validation studies, controlled trials, and other reports of near-infrared spectroscopy use in children and adults in the clinical setting. Guidelines published by the American Heart Association, the American Academy of Pediatrics, and the International Liaison Committee on Resuscitation were reviewed including further review of references cited.

RESULTS

The biophysical properties of near-infrared spectroscopy devices allow measurement of capillary-venous oxyhemoglobin saturation in tissues a few centimeters beneath the surface sensor with validated accuracy in neonates, infants, and small patients. The biologic basis for the relationship of capillary-venous oxyhemoglobin saturation to cerebral injury has been described in animal and human studies. Normal ranges for cerebral and somatic capillary-venous oxyhemoglobin saturation have been described for normal newborns and infants and children with congenital heart disease and other disease states. The capillary-venous oxyhemoglobin saturation from both cerebral and somatic regions has been used to estimate mixed venous saturation and to predict biochemical shock, multiorgan dysfunction, and mortality in different populations. The relationship of cerebral capillary-venous oxyhemoglobin saturation to neuroimaging and functional assessment of outcome is limited but ongoing. Although there are numerous conflicting reports in small populations, expert opinion would suggest that special use may exist for near-infrared spectroscopy in patients with complex circulatory anatomy, with extremes of physiology, and in whom extended noninvasive monitoring is useful.

CONCLUSIONS

Class II, level B evidence supports the conclusion that near-infrared spectroscopy offers a favorable risk-benefit profile and can be effective and beneficial as a hemodynamic monitor for the care of critically patients.

Gastrointestinal complications associated with the treatment of patients with congenital cardiac disease: consensus definitions from the Multi-Societal Database Committee for Pediatric and Congenital Heart Disease

A complication is an event or occurrence that is associated with a disease or a healthcare intervention, is a departure from the desired course of events, and may cause, or be associated with, suboptimal outcome. A complication does not necessarily represent a breech in the standard of care that constitutes medical negligence or medical malpractice. An operative or procedural complication is any complication, regardless of cause, occurring (1) within 30 days after surgery or intervention in or out of the hospital, or (2) after 30 days during the same hospitalization subsequent to the operation or intervention. Operative and procedural complications include both intraoperative/intraprocedural complications and postoperative/postprocedural complications in this time interval. The Multi-Societal Database Committee for Pediatric and Congenital Heart Disease has set forth a comprehensive list of complications associated with the treatment of patients with congenital cardiac disease, related to cardiac, pulmonary, renal, haematological, infectious, neurological, gastrointestinal, and endocrinal systems, as well as those related to the management of anaesthesia and perfusion, and the transplantation of thoracic organs. The objective of this manuscript is to examine the definitions of operative morbidity as they relate specifically to the gastrointestinal system. These specific definitions and terms will be used to track morbidity associated with surgical and transcatheter interventions and other forms of therapy in a common language across many separate databases. Although serious gastrointestinal complications are relatively uncommon after congenital cardiac surgery, accurate estimates of the incidences of these complications are limited, in part due to lack of standardized reporting and the absence of universal nomenclature that defines organ-specific complications. The Multi-Societal Database Committee for Pediatric and Congenital Heart Disease has prepared and defined a list of gastrointestinal complications that may be temporally associated with congenital cardiac surgery. Clinicians caring for patients with congenital cardiac disease will be able to use this list for databases, initiatives to improve quality, reporting of complications, and comparing strategies of treatment.

Glucosamine administration during resuscitation improves organ function after trauma hemorrhage

Stress-induced hyperglycemia is necessary for maximal rates of survival after severe hemorrhage; however, the responsible mechanisms are not clear. One consequence of hyperglycemia is an increase in hexosamine biosynthesis, which leads to increases in levels of O-linked attachment of N-acetyl-glucosamine (O-GlcNAc) on nuclear and cytoplasmic proteins. This modification has been shown to lead to improved survival of isolated cells after stress. In view of this, we hypothesized that glucosamine (GlcNH2), which more selectively increases the levels of O-GlcNAc administration after shock, will have salutary effects on organ function after trauma hemorrhage (TH). Fasted male rats that underwent midline laparotomy were bled to a mean arterial blood pressure of 40 mmHg for 90 min and then resuscitated with Ringer lactate (four times the shed blood volume). Administration of 2.5 mL of 150 mmol L GlcNH2 midway during resuscitation improved cardiac output 2-fold compared with controls that received 2.5 mL of 150 mmol L NaCl. GlcNH2 also improved perfusion of various organs systems, including kidney and brain, and attenuated the TH-induced increase in serum levels of IL-6 (902+/-224 vs. 585+/-103 pg mL) and TNF-alpha (540+/-81 vs. 345+/-110 pg mL) (values are mean+/-SD). GlcNH2 administration resulted in significant increase in protein-associated O-GlcNAc in the heart and brain after TH. Thus, GlcNH2 administered during resuscitation improves recovery from TH, as assessed by cardiac function, organ perfusion, and levels of circulating inflammatory cytokines. This protection correlates with enhanced levels of nucleocytoplasmic protein O-GlcNAcylation and suggests that increased O-GlcNAc could be the mechanism that links stress-induced hyperglycemia to improved outcomes.

Assessment and treatment of perfusion abnormalities in the emergency patient

Many patients presented to the emergency veterinarian are suffering from global or local tissue hypoperfusion. Global or systemic hypoperfusion can occur secondary to a reduction in the effective circulating intravascular volume (hypovolemic shock) or reduced ability of the heart to pump blood around the body secondary to reduced cardiac function (cardiogenic shock),obstruction to blood flow (obstructive shock), or maldistribution of the circulating intravascular volume (distributive shock). Initial assessment involving physical examination supplemented by measurement of hemodynamic and metabolic parameters allows the clinician to recognize and treat patients with severe global hypoperfusion. Use of techniques like sublingual capnometry and measurement of central venous oxygen saturation may aid recognition and evaluation of early hypoperfusion. Treatment decisions are made based on an assessment of the severity of the hypoperfusion and its probable underlying cause. Early effective treatment of hypoperfusion is likely to lead to a better outcome for the patient.

Noninvasive assessment of cardiac output

Improved outcome from shock depends on early detection and correction of circulatory abnormalities. Global cardiac output and oxygen delivery must be adequate and distributed appropriately to meet metabolic demands to prevent the development of multiple organ system dysfunction, prolonged morbidity, and death. Circulatory assessment using standard monitors gives incomplete and sometimes misleading information. This article focuses on the available and emerging technologies that emphasize assessment of blood flow and regional tissue oxygenation.

Hemoglobin-vesicles suspended in recombinant human serum albumin for resuscitation from hemorrhagic shock in anesthetized rats*

OBJECTIVE

Hemoglobin-vesicle (HbV) has been developed to provide oxygen-carrying ability to plasma expanders. Its ability to restore the systemic condition after hemorrhagic shock was evaluated in anesthetized Wistar rats for 6 hrs after resuscitation. The HbV was suspended in 5 g/dL recombinant human serum albumin (HbV/rHSA) at an Hb concentration of 8.6 g/dL.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Department of Surgery, School of Medicine, Keio University.

SUBJECTS

Forty male Wistar rats.

INTERVENTIONS

The rats were anesthetized with 1.5% sevoflurane inhalation throughout the experiment. Polyethylene catheters were introduced through the right jugular vein into the right atrium for infusion and into the right common carotid artery for blood withdrawal and mean arterial pressure monitoring.

MEASUREMENTS AND MAIN RESULTS

Shock was induced by 50% blood withdrawal. The rats showed hypotension (mean arterial pressure = 32 +/- 10 mm Hg) and significant metabolic acidosis and hyperventilation. After 15 mins, they received HbV/rHSA, shed autologous blood (SAB), washed homologous red blood cells (wRBC) suspended in rHSA (wRBC/rHSA, [Hb] = 8.6 g/dL), or rHSA alone. The HbV/rHSA group restored mean arterial pressure to 93 +/- 8 mm Hg at 1 hr, similar to the SAB group (92 +/- 9 mm Hg), which was significantly higher compared with the rHSA (74 +/- 9 mm Hg) and wRBC/rHSA (79 +/- 8 mm Hg) groups. There was no remarkable difference in the blood gas variables between the resuscitated groups; however, two of eight rats in the rHSA group died before 6 hrs. After 6 hrs, the rHSA group showed significant ischemic changes in the right cerebral hemisphere relating to the ligation of the right carotid artery followed by cannulation, whereas the HbV/rHSA, SAB, and wRBC/rHSA groups showed less changes.

CONCLUSIONS

HbV suspended in recombinant human serum albumin provides restoration from hemorrhagic shock that is comparable with that using shed autologous blood.

Detection of organ ischemia during hemorrhagic shock

BACKGROUND

In a porcine hemorrhagic shock model we aimed to determine: (a) whether blood flow to the intestine and kidney was more reduced than cardiac output; (b) whether parameters of anaerobic metabolism correlated with regional blood flow; and (c) whether metabolic parameters in intestine, kidney and skeletal muscles detected a compromised metabolic state at an earlier stage than did systemic parameters.

METHODS

In an animal research laboratory at a university hospital six domestic pigs were subjected to volume-controlled hemorrhage. Every 30 min samples of blood were withdrawn. Systemic and regional hemodynamic parameters and tissue levels of PCO2 were monitored. Whole body and organ-specific oxygen consumption (VO2) and veno-arterial (VA) differences of lactate, glucose, potassium (K+), PCO2, H+ and base excess (BE) were calculated every 30 min.

RESULTS

With progressive hemorrhage, intestinal blood flow decreased to the same extent as cardiac output, whereas the reduction in renal blood flow was more pronounced. We found a concomitant reduction in VO2 (onset of supply dependent metabolism) in intestine, kidney and skeletal muscles. In muscular tissue PCO2 increased to levels three times higher than baseline, while renal and intestinal PCO2 increased eightfold. Supply dependency was associated with a concomitant increase in VA CO2 and VA H+. Also, VA lactate increased, mostly in intestine and least in skeletal muscle. Intestinal and renal VA K+ increased, while muscular VA K+ decreased. Arterial lactate and H+ increased considerably, whereas arterial BE decreased.

CONCLUSION

With progressive hemorrhage, renal blood flow, but not intestinal and skeletal muscle blood flow, was reduced more than cardiac output. Supply dependent oxygen metabolism (VO2) and organ acidosis occurred simultaneously in the three organs, despite differences in blood flow reductions. Organ ischemia coincided with a pronounced change in arterial lactate and systemic acid base parameters.

Subcutaneous microdialysis for metabolic monitoring in abdominal aortic surgery

Microdialysis, that is the sampling of interstitial fluid via semi-permeable tubes, has been shown to be suitable for detecting ischemic changes e.g. in brain and heart tissue. The purpose of the present study was to investigate the possibility of monitoring with subcutaneous microdialysis peri-operative metabolic sequelac of elective abdominal aortic surgery. In 22 patients microdialysis catheters were inserted subcutaneously in the lower leg as well as the shoulder serving as a reference topographic region. Lactate, pyruvate and glycerol, which indicate ischemia or reperfusion, were measured. We observed severe metabolic changes within the interstitial fluid of the lower extremity during ischemia followed by normalization during reperfusion. Despite high interstitial concentrations of lactate and glycerol indicating severe ischemia during clamping of the abdominal aorta these parameters returned to pre-operative values within 2 hrs after declamping and all patients recovered completely.

OBJECTIVE

Information about the metabolic state of the lower extremity during and after infrarenal aortic aneurysm repair should modify peri-operative treatment. The aim of the study was to evaluate whether microdialysis of the subcutaneous tissue reflects metabolic changes during ischemia and reperfusion. Lactate, pyruvate and glycerol concentrations were measured in the subcutaneous tissue of the lower extremity and compared to the microdialysis measurements from shoulder subcutaneous tissue.

METHOD

In 22 patients microdialysis catheters were inserted preoperatively in the subcutaneous space of the left shoulder and the left calf. Samples were taken at timed intervals before, during and after clamping of the abdominal aorta.

RESULTS

The subcutaneous glycerol concentration of the calf was increased during the clamping period from initially 68 +/- 11 microM up to 182 +/- 27 microM (p < 0.05); the lactate/pyruvate (L/P) ratio was increased eightfold. After declamping these values normalized to baseline. Microdialysis measurements of the shoulder showed no prominent changes during the entire course of observation.

CONCLUSIONS

Subcutaneous microdialysis was able to detect metabolic changes due to ischemia during clamping of the abdominal aorta as well as reperfusion there after. It is a suitable technique to monitor the peri-operative course of the dependent tissue after abdominal aortic vascular surgery.