Haemodynamic coherence in haemorrhagic shock

Early diagnosis of sepsis-associated AKI: based on destruction-replenishment contrast-enhanced ultrasonography

Objective

Establish a deep learning ultrasound radiomics model based on destruction-replenishment contrast-enhanced ultrasound (DR-CEUS) for the early prediction of acute kidney injury (SA-AKI).

Method

This paper proposes a deep learning ultrasound radiomics model (DLUR). Deep learning models were separately established using ResNet18, ResNet50, ResNext18, and ResNext50 networks. Based on the features extracted from the fully connected layers of the optimal model, a deep learning ultrasound radiomics model (DLUR) was established using three classification models (built with 3 classifiers). The predictive performance of the best DLUR model was compared with the visual assessments of two groups of ultrasound physicians with varying levels of experience. The performance of each model and the ultrasound physicians was evaluated by assessing the receiver operating characteristic (ROC) curves. The area under the curve (AUC), sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were subsequently calculated.

Results

Compared to the ResNet18 model, the DLUR model based on logistic regression (DLUR-LR) demonstrated the best predictive performance, showing a Net Reclassification Improvement (NRI) value of 0.210 (p < 0.05). The Integrated Discrimination Improvement (IDI) value for the corresponding stage was 0.169 (p < 0.05). Additionally, the performance of the DLUR-LR model also surpassed that of senior ultrasound physicians (AUC, 0.921 vs. 0.829, p < 0.05).

Conclusion

By combining deep learning and ultrasound radiomics, a deep learning ultrasound radiomics model with outstanding predictive efficiency and robustness has demonstrated excellent capability in the early prediction of acute kidney injury (SA-AKI).

Bergapten attenuates hemorrhagic shock induced multi-organ injury by inhibiting NLRP3 inflammasome activation and pyroptosis

OBJECTIVES

Treatment of hemorrhagic shock (HS) induced multi-organ injury remains a challenge. Bergapten (BeG) is a bioactive coumarin-derived compound, and previous articles have suggested that BeG may serve as a prospective therapeutic modality for HS. This study was designed to investigate the efficacy of BeG in the treatment of HS and its underlying mechanisms.

METHODS

In this research, we established a rat model of HS, following which we assessed the protective effects of BeG on HS induced multi-organ injury. Subsequently, we scrutinized the activation of NLRP3 inflammasomes and pyroptosis in damaged organs. Additionally, we conducted examinations of AMPK and the downstream mitophagy pathway in damaged organs. Finally, we established a hypoxia/reoxygenation (H/R) model in HK-2 cells to simulate the in vitro HS process. Following AMPK inhibition with compound C, we evaluated the levels of mitophagy and cellular pyroptosis in BeG-treated HK-2 cells subjected to H/R.

RESULTS

BeG treatment alleviated HS induced multi-organ injury. Subsequent analyses indicated that the therapeutic effects of BeG were related to the attenuation of NLRP3 inflammasome activation and pyroptosis. Additionally, we found BeG treatment stimulated the phosphorylation of AMPK, thereby enhancing mitophagy. Lastly, we found that the inhibition of AMPK in vitro attenuates BeG's enhancement of mitophagy and its suppression of pyroptosis.

CONCLUSION

Our research indicates that BeG has the potential to alleviate multi-organ injury induced by HS. The protective effect of BeG is likely associated with its promotion of mitophagy through AMPK activation, thereby inhibiting NLRP3 inflammasome-mediated pyroptosis.

Post-occlusive reactive hyperemia variables can be used to diagnose vascular dysfunction in hemorrhagic shock

INTRODUCTION

Laser doppler flowmetry (LDF) allows non-invasive assessment of microvascular functions. The combination of LDF with an occlusion functional test enables study of post-occlusive reactive hyperemia (PORH), providing additional information about vasomotor function, capillary blood flow reserve, and the overall reactivity of the microvascular system.

AIM

To identify early alterations of PORH variables in the skin of a rat in hemorrhagic shock (HS).

MATERIAL AND METHODS

Male Wistar rats (n = 14) weighing 400-450 g were anesthetized with a combination of tiletamine/zolazepam (20 mg/kg) and xylazine (5 mg/kg). The animals breathed on their own, and were placed on a heated platform in the supine position. A PE-50 catheter was inserted into the carotid artery to measure the mean arterial pressure (MAP). The optical probe of the Laser Doppler device was installed on the plantar surface of the hind limb of a rat; a pneumatic cuff was applied proximal to the same limb. The occlusion time was 3 min. The following physiological variables were measured at baseline and 30 min after blood loss: MAP, mmHg; mean cutaneous blood flow (M, PU); cutaneous vascular conductance (CVC = M/MAP); peak hyperemia (Mmax, PU) and maximum cutaneous vascular conductance (CVCmax) during PORH. In the HS group (n = 7), 30 % of the estimated blood volume was taken within 5 min. There was no blood loss in the group of sham-operated animals (Sham, n = 7). The results are presented as Me [25 %;75 %]. The U-Mann-Whitney criterion was used to evaluate intergroup differences. Differences were considered statistically significant at p < 0.05.

RESULTS

The groups did not differ at baseline. Blood loss led to a significant decrease in MAP (43 [31;46] vs. 94 [84;104] mmHg), M (11.5 [16.9;7.8] vs 16.7 [20.2;13.9]) and Mmax (18.1 [16.4;21.8] vs. 25.0 [23.0;26.2]) in the HS group compared to the Sham group, respectively. At the same time, both CVC (0.25 [0.23;0.30] vs. 0.16 [0.14;0.21]) and CVCmax (0.55 [0.38;0.49] vs 0.24 [0.23; 0.29]) increased after blood loss in the HS group compared to the Sham group. Arterial blood gas analysis revealed metabolic lactic acidosis in the HS group.

CONCLUSION

In this rat model of HS, alterations in cutaneous blood flow are manifested by a decrease in perfusion (M) and the intensity of PORH (Mmax) with a simultaneous increase in vascular conductance (CVC and CVCmax).

Effect of Respiratory Failure on Peripheral and Organ Perfusion Markers in Severe COVID-19: A Prospective Cohort Study

Microvascular dysfunction and inflammation caused by COVID-19 disrupt organ function. The study aimed to investigate the association between the severity of SARS-CoV-2 pneumonia and peripheral and organ perfusion as a consequence of altered microcirculation. A total of 116 patients hospitalized due to severe COVID-19 were enrolled in the study. On admission, the patients underwent a Capillary Refill Time (CRT) examination, finger oxygen saturation measurement, thermal imaging of the hand (FIT), and a kidney Doppler ultrasound. Medical data were collected from the medical history. From the evaluated perfusion parameters, only renal cortex perfusion (RCP) was substantially correlated with the CT score (p < 0.010). The peripheral perfusion parameters of Sat., FIT, CRT, and RCP correlated with the ARDS stages (p = 0.0021; p = 0.038; p < 0.0006; p < 0.0002, respectively). The Oxygenation Ratio value (p < 0.001) was significantly associated with all the perfusion parameters (saturation, CRT, FIT, and RCP) in the multivariable regression analysis model. According to the stepwise retrograde regression analysis, RCP was an independent parameter linked with the Oxygenation Ratio (p < 0.001). Severe COVID-19 can result in microvascular dysfunction influencing peripheral and organ perfusion, which can be measured with various methods. The staging of COVID-19 assessed by CT and the Oxygenation Ratio correlates with RCP, CRT, FIT, and oxygen saturation.

Microcirculatory effects of rewarming in experimental hemorrhagic shock

BACKGROUND

Rewarming is a recommended therapy during the resuscitation of hypothermic patients with hemorrhagic shock. In experimental models, however, it increases inflammatory response and mortality. Although microcirculation is potential target of inflammation, the microvascular effects of rewarming during the resuscitation of hemorrhagic shock have not been studied. Our goal was to assess the systemic and microcirculatory effects of an increase in core temperature (T°) during the retransfusion of hemorrhagic shock in sheep. Our hypothesis was that rewarming could hamper microcirculation.

METHODS

In anesthetized and mechanically ventilated sheep, we measured systemic, intestinal, and renal hemodynamics and oxygen transport. O₂ consumption (VO₂) and respiratory quotient were measured by indirect calorimetry. Cortical renal, intestinal villi and sublingual microcirculation were assessed by IDF-videomicroscopy. After basal measurements, hemorrhagic shock was induced and T° was reduced to ~33 °C. After 1 h of shock and hypothermia, blood was retransfused and Ringer lactate solution was administered to prevent arterial hypotension. In the control group (n = 12), T° was not modified, while in the intervention (rewarming) group, it was elevated ~3 °C. Measurements were repeated after 1 h.

RESULTS

During shock, both groups showed similar systemic and microvascular derangements. After retransfusion, VO₂ remained decreased compared to baseline in both groups, but was lower in the control compared to the rewarming group. Perfused vascular density has a similar behavior in both groups. Compared to baseline, it remained reduced in peritubular (control vs. rewarming group, 13.8 [8.7-17.5] vs. 15.7 [10.1-17.9] mm/mm², PNS) and villi capillaries (14.7 [13.6-16.8] vs. 16.3 [14.2-16.9] mm/mm², PNS), and normalized in sublingual mucosa (19.1 [16.0-20.3] vs. 16.6 [14.7-17.2] mm/mm², PNS).

CONCLUSIONS

This is the first experimental study assessing the effect of rewarming on systemic, regional, and microcirculatory perfusion in hypothermic hemorrhagic shock. We found that a 3 °C increase in T° neither improved nor impaired the microvascular alterations that persisted after retransfusion. In addition, sublingual mucosa was less susceptible to reperfusion injury than villi and renal microcirculation.

Characteristics of sublingual microcirculatory changes during the early postoperative period following cardiopulmonary bypass-assisted cardiac surgery-a prospective cohort study

BACKGROUND

Persistent microcirculatory dysfunction associated with increased morbidity and mortality. Interventions in the early resuscitation can be tailored to the changes of microcirculation and patient's need. However, there is usually an uncoupling of macrocirculatory and microcirculatory hemodynamics during resuscitation. Current research on the patterns of microcirculatory changes and recovery after cardiopulmonary bypass (CPB)-assisted cardiac surgery is limited. This study aimed to analyze changes in the microcirculatory parameters after CPB and their correlation with macrocirculation and to explore the characteristics of microcirculatory changes following CPB-assisted cardiac surgery.

METHODS

Between December 2018 and January 2019, 24 adult patients with indwelling pulmonary artery catheters after elective cardiac surgery using CPB were enrolled in this study. Both microcirculatory and macrocirculatory parameters were collected at 0, 6, 16, and 24 hours after admission to the intensive care unit (ICU). Video images of sublingual microcirculation were analyzed to obtain the microcirculatory parameters, including total vascular density (TVD), perfused small vessel density (PSVD), the proportion of perfused small vessels (PPV), microvascular flow index (MFI), and flow heterogeneity index (HI). The characteristics of microcirculatory parameter change following cardiac surgery and the correlation between microcirculatory parameters and macroscopic hemodynamic indicators, oxygen metabolic indicators, and carbon dioxide partial pressure difference (PCO2gap) were analyzed.

RESULTS

There were significant differences in the changes of TVD (P=0.012) and PSVD (P=0.005) during the first 24 hours postoperatively in patients who underwent CPB-assisted cardiac surgery. The microcirculatory density parameters (TVD: r=-0.5059, P=0.0456; PVD: r=-0.5499, P=0.0273) were correlated with oxygen delivery index (DO2I) at 24 hours after surgery. The microcirculatory flow parameters (PPV: r=0.4370, P=0.0327; MFI: r=0.6496, P=0.0006; and HI: r=-0.5350, P=0.0071) had a strong correlation with PCO2gap at 0 hour after surgery.

CONCLUSIONS

TVD and PSVD might be two most sensitive indicators affected by CPB-assisted cardiac surgery. There was no consistency between microcirculation and macrocirculation until 24 hours following cardiac surgery, meaning the improvement of systemic hemodynamic indicators does not guarantee correspondently improvement in microcirculation. Early controlled oxygen supply after CPB-assisted cardiac surgery may be conducive to the resuscitation of patients to a certain extent.

Effects of Systemic Hypothermia on Microcirculation in Conditions of Hemodynamic Stability and in Hemorrhagic Shock

INTRODUCTION

Although hypothermia is independently associated with an increased mortality in trauma patients, it might be an effective therapeutic approach for otherwise lethal hemorrhage. The effect of hypothermia on microcirculation, however, has been poorly studied in this setting. Our goal was to characterize the effects of hypothermia on microcirculation in normal conditions and in severe hemorrhagic shock.

METHODS

In anesthetized and mechanically ventilated sheep, we measured cardiac output (CO), renal blood flow (RBF), and systemic and renal O2 consumption (VO2). Cortical renal, intestinal villi, and sublingual microcirculation was assessed by IDF-videomicroscopy. After basal measurements, sheep were assigned to hypothermia (n = 12) and normothermia (n = 12) groups. Central temperature was reduced to ∼34°C and maintained at baseline in each group, respectively. Measurements were repeated after 1 h of hemodynamic stable conditions and 1 h of severe hemorrhagic shock.

RESULTS

In conditions of hemodynamic stability, the hypothermia group showed lower CO, RBF, and systemic and renal VO2 than the normothermia group. Red blood cell velocity was also lower in renal, villi, and sublingual microvascular beds (836 ± 195 vs. 1,066 ± 162, 916 ± 105 vs. 1051 ± 41, and 970 ± 182 vs. 1,102 ± 49 μm/s, respectively; P < 0.0001 for all). In hemorrhagic shock, most of the microvascular variables were similarly compromised in both the groups. In hypo- and normothermia groups, the percentage of reduction in perfused vascular density was higher in renal than in intestinal and sublingual microcirculation (66 ± 31 vs. 31 ± 23 and 15 ± 15%, and 78 ± 26 vs. 32 ± 37 and 18 ± 21%, P < 0.01 for both).

CONCLUSIONS

This is the first experimental study assessing the effect of systemic hypothermia on microcirculation in severe hemorrhagic shock. The main finding was that hypothermia did not hamper additionally the microcirculatory derangements induced by hemorrhagic shock. In addition, renal microcirculation was more susceptible to hemorrhagic shock than villi and sublingual microcirculation.

The effect of moderate intraoperative blood loss and norepinephrine therapy on sublingual microcirculatory perfusion in patients having open radical prostatectomy: An observational study

BACKGROUND

It is not clear whether moderate intraoperative blood loss and norepinephrine used to restore the macrocirculation impair the microcirculation and affect microcirculation/macrocirculation coherence.

OBJECTIVE

We sought to investigate the effect of moderate intraoperative blood loss and norepinephrine therapy administered to treat intraoperative hypotension on the sublingual microcirculation.

DESIGN

Prospective observational study.

SETTING

University Medical Center Hamburg-Eppendorf, Hamburg, Germany, from November 2018 to March 2019.

PATIENTS

Thirty patients scheduled for open radical prostatectomy and 29 healthy volunteer blood donors.

INTERVENTION

Simultaneous assessment of the macrocirculation using a noninvasive finger-cuff method and the sublingual microcirculation using vital microscopy.

MAIN OUTCOME MEASURES

The main outcome measures were changes in the sublingual microcirculation caused by moderate intraoperative blood loss and norepinephrine therapy.

RESULTS

General anaesthesia decreased median [IQR] mean arterial pressure from 100 [90 to 104] to 79 [69 to 87] mmHg (P < 0.001), median heart rate from 69 [63 to 79] to 53 [44 to 62] beats per minute (P < 0.001), median cardiac index from 2.67 [2.42 to 3.17] to 2.09 [1.74 to 2.49] l min-1 m-2 (P < 0.001), and median microvascular flow index from 2.75 [2.66 to 2.85] to 2.50 [2.35 to 2.63] (P = 0.001). A median blood loss of 600 [438 to 913] ml until the time of prostate removal and norepinephrine therapy to treat intraoperative hypotension had no detrimental effect on the sublingual microcirculation: There were no clinically important changes in the microvascular flow index, the proportion of perfused vessels, the total vessel density, and the perfused vessel density. Blood donation resulted in no clinically important changes in any of the macrocirculatory or microcirculatory variables.

CONCLUSION

Moderate intraoperative blood loss and norepinephrine therapy administered to treat intraoperative hypotension have no detrimental effect on the sublingual microcirculation and the coherence between the macrocirculation and microcirculation in patients having open radical prostatectomy.

The Influence of Hemorrhagic Shock on the Disposition and Effects of Intravenous Anesthetics: A Narrative Review

The need to reduce the dose of intravenous anesthetic in the setting of hemorrhagic shock is a well-established clinical dogma. Considered collectively,; the body of information concerning the behavior of intravenous anesthetics during hemorrhagic shock, drawn from animal and human data, confirms that clinical dogma and informs the rational selection and administration of intravenous anesthetics in the setting of hemorrhagic shock. The physiologic changes during hemorrhagic shock can alter pharmacokinetics and pharmacodynamics of intravenous anesthetics. Decreased size of the central compartment and central clearance caused by shock physiology lead to an altered dose-concentration relationship. For most agents and adjuncts, shock leads to substantially higher concentrations and increased effect. The notable exception is etomidate, which has relatively unchanged pharmacokinetics during shock. Increased concentrations lead to increased primary effect as well as increased side effects, notably cardiovascular effects. Pharmacokinetic changes are essentially reversed for all agents by fluid resuscitation. Propofol is unique among agents in that, in addition to the pharmacokinetic changes, it exhibits increased potency during shock. The pharmacodynamic changes of propofol persist despite fluid resuscitation. The persistence of these pharmacodynamic changes during shock is unlikely to be due to increased endogenous opiates, but is most likely due to increased fraction of unbound propofol. The stage of shock also appears to influence the pharmacologic changes. The changes are more rapid and pronounced as shock physiology progresses to the uncompensated stage. Although scant, human data corroborate the findings of animal studies. Both the animal and human data inform the rational selection and administration of intravenous anesthetics in the setting of hemorrhagic shock. The well-entrenched clinical dogma that etomidate is a preferred induction agent in patients experiencing hemorrhagic shock is firmly supported by the evidence. Propofol is a poor choice for induction or maintenance of anesthesia in severely bleeding patients, even with resuscitation; this can include emergent trauma cases or scheduled cases that routinely have mild or moderate blood loss.

Variations of Cutaneous Capnometry and Perfusion Index During a Heating Challenge is Early Impaired in Septic Shock and Related to Prognostic in Non-Septic Shock

INTRODUCTION

In shock, the increase in cutaneous-to-arterial carbon dioxide partial pressure (Pc-aCO2) and the decrease in the perfusion index (PI) are related to macrovascular or microvascular alterations. We hypothesized that inducing cutaneous vasodilation and local perfusion with heat could provide a noninvasive tool to monitor microvascular reactivity.

OBJECTIVES

This study aimed to develop a noninvasive approach, the heating challenge (HC), to monitor the microvascular reactivity of patients with shock and to evaluate the potential relationship with outcome.

METHODS

After ethics committee agreement was obtained, 59 shock patients, including 37 septic shock, 22 non-septic shock (14 cardiogenic and eight hemorrhagic), 10 intensive care unit (ICU)-controls and 12 healthy volunteers, were included in this study. The HC consisted of heating the ear lobe PcCO2 sensor from 37° to 45° over 5 min and recording PcCO2 and PI variations (ΔPcCO2 and PImax/min). HC was performed on admission and during the first 48 h of hospitalization.

RESULTS

Pc-aCO2 was significantly higher in shock patients than ICU-controls at baseline (P < 0.05). HC led to a decrease in PcCO2 and an increase in PI in the healthy volunteers (ΔPcCO2 = -9.0 ± 4.6% and PImax/min = 5.5 ± 1.9). On admission, non-septic shock patients (cardiogenic and hemorrhagic shocks) had an HC response profile identical to that of healthy volunteers and ICU-controls. In contrast, septic shock patients had a lower ΔPcCO 2 and PImax/min compared to healthy volunteers and all other groups (P < 0.05). After the first day, the combination of a Pc-aCO2 >17 mm Hg with a positive ΔPcCO2 could predict mortality with a specificity of 82% and a sensitivity of 93%.

CONCLUSIONS

HC appears to be a dynamic test to classify vascular reactivity alterations in shock. At baseline, HC results were impaired in septic patients and conserved in non-septic patients. After the first day, the association between Pc-aCO2 and ΔPcCO2 was strongly related to prognosis in shock patients.

[Hypovolemic and hemorrhagic shock]

The term "shock" refers to a life-threatening circulatory failure caused by an imbalance between the supply and demand of cellular oxygen. Hypovolemic shock is characterized by a reduction of intravascular volume and a subsequent reduction in preload. The body compensates the loss of volume by increasing the stroke volume, heart frequency, oxygen extraction rate, and later by an increased concentration of 2,3-diphosphoglycerate with a rightward shift of the oxygen dissociation curve. Hypovolemic hemorrhagic shock impairs the macrocirculation and microcirculation and therefore affects many organ systems (e.g. kidneys, endocrine system and endothelium). For further identification of a state of shock caused by bleeding, vital functions, coagulation tests and hematopoietic procedures are implemented. Every hospital should be in possession of a specific protocol for massive transfusions. The differentiated systemic treatment of bleeding consists of maintenance of an adequate homeostasis and the administration of blood products and coagulation factors.

Cerebral Blood Flow in Polytrauma: Transcranial Doppler Analysis in a Nonhuman Primate Shock Model

BACKGROUND

In combat-related trauma, resuscitation goals are to attenuate tissue hypoxia and maintain circulation. During hemorrhagic shock, compensatory and autoregulatory mechanisms are activated to preserve cerebral blood flow. Transcranial Doppler (TCD) ultrasonography may be an ideal noninvasive modality to monitor cerebral hemodynamics. Using a nonhuman primate (NHP) model, we attempted to characterize cerebral hemodynamics during polytraumatic hemorrhagic shock using TCD ultrasonography.

MATERIALS AND METHODS

The ophthalmic artery was insonated at multiple time points during varying stages of shock. Hemorrhage was controlled and pressure targeted to 20 mmHg to initiate and maintain the shock period. Mean flow velocity (MFV), peak systolic velocity (PSV), end diastolic velocity (EDV), pulsatility index (PI), and resistance index (RI) were recorded. Results represent mean ± standard deviation; statistical significance is P < 0.05; n = 12.

RESULTS

Compared to baseline, MFV, PSV, EDV, and RI show significant changes after 60 min of hemorrhagic shock, (9.81 ± 3.60 cm/s; P < 0.01), (21.15 ± 8.59 cm/s; P < 0.01), (5.15 ± 0.21 cm/s; P < 0.01), (0.70 ± 0.11; P < 0.05), respectively. PI did not change during hemorrhagic shock. At end of prehospital care (T30), cerebral flow recovers for MFV, PSV, and RI while EDV remained decreased at T30 (6.15 ± 1.13 cm/s; P < 0.01) and 1 h of simulated transport (T90) (5.87 ± 0.62 cm/s; P < 0.01). Changes in PI at T30 and T90 were not significant. MFV diminished (16.45 ± 3.85 cm/s; P < 0.05) at T90.

CONCLUSIONS

This study establishes baseline and hemorrhagic shock values for NHP cerebral blood flow velocities and cerebrovascular indices. TCD ultrasonography may represent an important area of research for targeted resuscitation investigations using a hemorrhagic shock model in NHPs.

Acute kidney injury is associated with a decrease in cortical renal perfusion during septic shock

Background

Renal perfusion status remains poorly studied at the bedside during septic shock. We sought to measure cortical renal perfusion in patients with septic shock during their first 3 days of care using renal contrast enhanced ultrasound (CEUS).

Methods

We prospectively included 20 ICU patients with septic shock and 10 control patients (CL) without septic shock admitted to a surgical ICU. Cortical renal perfusion was evaluated with CEUS during continuous infusion of Sonovue (Milan, Italy) within the first 24 h (day 0), between 24 and 48 h (day 1) and after 72 h (day 3) of care. Each measurement consisted of three destruction replenishment sequences that were recorded for delayed analysis with dedicated software (Vuebox). Renal perfusion was quantified by measuring the mean transit time (mTT) and the perfusion index (PI), which is the ratio of renal blood volume (rBV) to mTT.

Results

Cortical renal perfusion was decreased in septic shock as attested by a lower PI and a higher mTT in patients with septic shock than in patients of the CL group (p = 0.005 and p = 0.03). PI values had wider range in patients with septic shock (median (min-max) of 74 arbitrary units (a.u.) (3–736)) than in patients of the CL group 228 a.u. (67–440)). Renal perfusion improved over the first 3 days with a PI at day 3 higher than the PI at day 0 (74 (22–120) versus 160 (88–245) p = 0.02). mTT was significantly higher in patients with severe acute kidney injury (AKI) (n = 13) compared with patients with no AKI (n = 7) over time (p = 0.005). The PI was not different between patients with septic shock with severe AKI and those with no AKI (p = 0.29).

Conclusions

Although hemodynamic macrovascular parameters were restored, the cortical renal perfusion can be decreased, normal or even increased during septic shock. We observed an average decrease in cortical renal perfusion during septic shock compared to patients without septic shock. The decrease in cortical renal perfusion was associated with severe AKI occurrence. The use of renal CEUS to guide renal perfusion resuscitation needs further investigation.

A clinically relevant and bias-controlled murine model to study acute traumatic coagulopathy

Acute traumatic coagulopathy (ATC) is an acute and endogenous mechanism triggered by the association of trauma and hemorrhage. Several animal models have been developed, but some major biases have not yet been identified. Our aim was to develop a robust and clinically relevant murine model to study this condition. Anesthetized adult Sprague Dawley rats were randomized into 4 groups: C, control; T, trauma; H, hemorrhage; TH, trauma and hemorrhage (n = 7 each). Trauma consisted of laparotomy associated with four-limb and splenic fractures. Clinical variables, ionograms, arterial and hemostasis blood tests were compared at 0 and 90 min. ATC and un-compensated shock were observed in group TH. In this group, the rise in prothrombin time and activated partial thromboplastin was 29 and 40%, respectively. Shock markers, compensation mechanisms and coagulation pathways were all consistent with human pathophysiology. The absence of confounding factors, such as trauma-related bleeding or dilution due to trans-capillary refill was verified. This ethic, cost effective and bias-controlled model reproduced the specific and endogenous mechanism of ATC and will allow to identify potential targets for therapeutics in case of trauma-related hemorrhage.

Effects of Fluids on the Macro- and Microcirculations

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2018. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2018. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Intestinal microcirculation and mucosal oxygenation during hemorrhagic shock and resuscitation at different inspired oxygen concentrations

BACKGROUND

Hypotensive resuscitation is the standard of care of hemorrhagic shock resuscitation. The optimal level of arterial pressure is debated and there is a lack of data on relationships between arterial pressure, microcirculation and tissue oxygenation. We investigated the relationship between mean arterial pressure, intestinal microcirculation and mucosal oxygen tension during hemorrhagic shock and resuscitation at different inspired oxygen fraction concentration.

METHODS

The study was divided into two phases: 32 mice were progressively exsanguinated and then transfused in mean arterial pressure (MAP)-titrated steps of 10 mm Hg. Mice were randomized to four experimental groups: a control group in which sham mice underwent a laparotomy and three interventional groups with a common phase of exsanguination followed by progressive resuscitation at three different inspired oxygen concentrations (FIO2) (15%, 30%, and 100%). Intestinal mucosal oxygenation (intestinal PO2) and microcirculatory parameters were recorded at each 10 mm Hg MAP step.

RESULTS

During exsanguination, intestinal PO2 decreased linearly with MAP levels. Microcirculatory parameters decreased nonlinearly with MAP levels while they had a linear relationship with intestinal PO2. Intestinal mucosal hypoxia (PO2 ≤ 20 mm Hg) began at a MAP of 60 mm Hg and MAP < 60 mm Hg was associated with a high percentage of animal with intestinal hypoxia (≥32%). Combination of MAP and microcirculatory parameters was superior to MAP alone at predicting mucosal oxygenation. Inversely, during resuscitation with FIO2 = 30%, the microcirculatory parameters increased linearly with MAP levels while they had a nonlinear relationship with intestinal PO2. Hypoxia (FIO2 = 15%) was poorly tolerated. In hyperoxic group (FIO2 = 100%) intestinal PO2 became significantly higher than baseline values as soon as 50 mm Hg MAP.

CONCLUSION

During hemorrhagic shock, intestinal PO2 decreased linearly with MAP levels and microcirculatory parameters. Associating MAP and microcirculatory parameters allowed a better prediction of intestinal PO2 than MAP alone. A MAP < 60 mm Hg was associated with a high percentage of animal with intestinal hypoxia. Normoxic resuscitation (FIO2 = 30%) was sufficient to restore intestinal PO2.