Non-invasive detection of a femoral-to-radial arterial pressure gradient in intensive care patients with vasoactive agents

Background In patient requiring vasopressors, the radial artery pressure may underestimate the true central aortic pressure leading to unnecessary interventions. When using a femoral and a radial arterial line, this femoral-to-radial arterial pressure gradient (FR-APG) can be detected. Our main objective was to assess the accuracy of non-invasive blood pressure (NIBP) measures; specifically, measuring the gradient between the NIBP obtained at the brachial artery and the radial artery pressure and calculating the non-invasive brachial-to-radial arterial pressure gradient (NIBR-APG) to detect an FR-APG. The secondary objective was to assess the prevalence of the FR-APG in a targeted sample of critically ill patients. Methods Adult patients in an intensive care unit requiring vasopressors and instrumented with a femoral and a radial artery line were selected. We recorded invasive radial and femoral arterial pressure, and brachial NIBP. Measurements were repeated each hour for 2 h. A significant FR-APG (our reference standard) was defined by either a mean arterial pressure (MAP) difference of more than 10 mmHg or a systolic arterial pressure (SAP) difference of more than 25 mmHg. The diagnostic accuracy of the NIBR-APG (our index test) to detect a significant FR-APG was estimated and the prevalence of an FR-APG was measured and correlated with the NIBR-APG. Results Eighty-one patients aged 68 [IQR 58–75] years and an SAPS2 score of 35 (SD 7) were included from which 228 measurements were obtained. A significant FR-APG occurred in 15 patients with a prevalence of 18.5% [95%CI 10.8–28.7%]. Diabetes was significantly associated with a significant FR-APG. The use of a 11 mmHg difference in MAP between the NIBP at the brachial artery and the MAP of the radial artery led to a specificity of 92% [67; 100], a sensitivity of 100% [95%CI 83; 100] and an AUC ROC of 0.93 [95%CI 0.81–0.99] to detect a significant FR-APG. SAP and MAP FR-APG correlated with SAP (r2 = 0.36; p < 0.001) and MAP (r2 = 0.34; p < 0.001) NIBR-APG. Conclusion NIBR-APG assessment can be used to detect a significant FR-APG which occur in one in every five critically ill patients requiring vasoactive agents.

Effects of Chengqi Decoction on Complications and Prognosis of Patients with Pneumonia-Derived Sepsis: Retrospective Cohort Study

Purpose. A specific and efficacious method for treatment of pneumonia-derived sepsis is lacking. Chengqi decoction has been used for treatment of pneumonia-derived sepsis, but a clinical trial on patients with pneumonia-derived sepsis is lacking, a gap in the literature that we sought to fill. Patients and Methods. 282 patients with pneumonia-derived sepsis admitted to the intensive care unit of our hospital were selected. They were divided into the treatment group (141 cases) and control group (141 cases). Both groups underwent conventional treatment, but Chengqi decoction (in the form of enema) was given to the treatment group. Mortality, morbidity (abdominal distension and gastrointestinal bleeding), duration of antibiotic use, and use of vasoactive agents were documented 28 days after the drug was used. Results. The treatment group reduced mortality and morbidity (abdominal distension) ( P < 0.05 ). After adjustment for significant covariates, 28-day survival was similar for the whole group (hazard ratio (HR): 0.48; 95% confidence interval (CI): 0.23–0.97; P = 0.037 ), for the subgroup (n = 120) with Acute Physiology and Chronic Health Evaluation II score ≥25 (HR: 0.180; 95% CI: 0.032–0.332; P = 0.039 ) and for the subgroup (n = 66) with N-terminal B-type natriuretic peptide <1800 (0.059, 0.004–0.979, and 0.019). There was no difference between the two groups for the duration of antibiotic use, major bleeding, or use of vasoactive drugs. Conclusions. Chengqi decoction improved 28-day survival and reduced the prevalence of abdominal distension in patients with pneumonia-derived sepsis.

Blood flow synchronization in renal microcirculation - a high-resolution imaging study.

Aims: internephron signalling and interaction are fundamental for kidney function. Earlier studies have shown that nephrons signal to each other over short distances and adjust their activity accordingly. Micropuncture experiments revealed synchronous clusters of 2-3 nephrons formed from such interactions, while imaging and modelling results suggested the possibility of larger clusters. Such clusters are expected to play an important role in renal autoregulation, but their presence has not been confirmed and their size has not been estimated. In this study, we present methodology for high resolution renal blood flow imaging and apply it to estimate frequency and phase angle differences in kidney blood vessels under normal conditions and after administration of the vasoactive agents angiotensin II and acetylcholine. Methods and results: to resolve signals from separate arterioles in a sufficiently large field of view, we developed a method for renal laser speckle contrast imaging. Our setup provides imaging of blood flow in the kidney cortex with a limit of image resolution at 0.8 micrometres per pixel and the imaging frequency of 160Hz. We used the method to record from ~1.5x1.5 mm2 sections of the renal surface in anaesthetised Sprague-Dawley rats in unstimulated conditions and during IV infusion of the vasoconstrictor angiotensin II or the vasodilator acetylcholine. In each section, we resolved and segmented 94.8+-15.66 individual arterioles and venules, and analyzed blood flow using wavelet spectral analysis to identify clusters of synchronized blood vessels. Conclusions: we observed spatial and temporal evolution of blood vessel clusters of various sizes, including the formation of large (>90 vessels) long-lived clusters (>10 periods) locked at the frequency of the tubular glomerular feedback (TGF) mechanism. The analysis showed that synchronization patterns and thus the co-operative dynamics of nephrons change significantly when either of the vasoactive agents is administered. On average, synchronization was stronger (larger clusters, longer duration) with angiotensin II administration than in the unstimulated state or with acetyl choline. While it weakens with distance, increased synchronization duration spanned the whole field of view, and likely, beyond it. Neighbouring vessels tend to demonstrate in-phase synchronization, especially in the vasoconstricted condition, which is expected to cause locally increased pressure variation. Our results confirm both the presence of the local synchronization in the renal microcirculatory blood flow and the fact that it changes depending on the condition of the vascular network and the blood pressure, which might have further implications for the role of such synchronization in pathologies development.

A method to evaluate dynamic cerebral pressure-flow relationships in the conscious rat

We present a novel technique to overcome the use of vasoactive agents when studying cerebrovascular dynamics in the conscious rat. Our method of vena cava occlusion to reduce BP was associated with decreased iCBF and no change in iCVR. In contrast, comparable BP falls with intravenous SNP increased iCBF and reduced iCVR. Thus, the dynamic cerebral pressure-flow relationship shows a narrower, less level autoregulatory plateau than conventionally thought. We confirm our method allows repeatable assessment of cerebrovascular dynamics in conscious rats.

Early Outcomes in Patients with Severe Dilated Left Ventricle Disease after Heart Valve Surgery

Objectives: The study sought to examine the prognostic impact of valvular surgery in patients with severe dilated left ventricle(DL) and assess morphological and functional changes of DL in the early period after operation. Methods: From January 2013 to December 2018, at a single center, 126 patients with severe dilated left ventricle (DL group) and 511 patients with 511 patients with normal sized left ventricle (NL group) underwent heart valve surgery. Retrospective review of the procedure and the postoperative clinical course, including echocardiography were analyzed in 6 to 12-month follow up. Results: Compared with NL group, DL group had significantly higher postoperative all-cause mortality (3.2% vs 1.4%) and complication rate, as well as longer duration of mechanical ventilation and vasoactive agents support. In DL group, 4 (3.2%) patients died in the early postoperative stage among which 2 (1.6%) patients died from multiple organ failure (MOF) secondary to severe low-output syndrome, 2 (1.6%) patients died from ventricular fibrillation. The DL group had longer time of mechanical ventilation and vasoactive agents support than NL group postoperatively. In DL group, the progressive regression of end-diastole diameter (LVEDD) was observed during the follow-up; whereas left ventricular ejection function (LVEF) and left ventricular fractional shortening (LVFS) showed a temporary decrease in early postoperative stage and then improved gradually. Conclusion: Heart valve surgery performed in an experienced center, along with sophisticated perioperative management, could bring satisfying early outcomes to patients with severe dilated left ventricle.

Vasoactive agents in acute mesenteric ischaemia in critical care. A systematic review

Background: Acute mesenteric ischaemia (AMI) is a surgical emergency which has an associated high mortality. The mainstay of active treatment includes early surgical intervention, with resection of non-viable bowel, and revascularisation of the ischaemic bowel where possible. Due to the physiological insult of AMI however, perioperative care often involves critical care and the use of vasoactive agents to optimise end organ perfusion. A number of these vasoactive agents are currently available with varied mechanism of action and effects on splanchnic blood flow. However, specific guidance on which is the optimal vasoactive drug to use in these settings is limited. This systematic review aimed to evaluate the current evidence comparing vasoactive drugs in AMI. Methods: A systematic search of Ovid Medline, Ovid Embase, Cochrane CENTRAL and the Cochrane Database of Systematic Review was performed on the 5th of November 2020 to identify randomised clinical trials comparing different vasoactive agents in AMI on outcomes including mortality. The search was performed through the Royal College of Surgeons of England (RCSEng) search support library. Results were analysed using the Rayyan platform, and independently screened by four investigators. Results: 614 distinct papers were identified. After screening, there were no randomised clinical trials meeting the inclusion criteria. Conclusions: This review identifies a gap in literature, and therefore recommends an investigation into current practice and clinician preference in relation to vasoactive agents in AMI. Multicentre randomised controlled trials comparing these medications on clinical outcomes will therefore be required to address this question.

Vasoactive agents in acute mesenteric ischaemia in critical care. A systematic review

Background: Acute mesenteric ischaemia (AMI) is a surgical emergency which has an associated high mortality. The mainstay of active treatment includes early surgical intervention, with resection of non-viable bowel, and revascularisation of the ischaemic bowel where possible. Due to the physiological insult of AMI however, perioperative care often involves critical care and the use of vasoactive agents to optimise end organ perfusion. A number of these vasoactive agents are currently available with varied mechanism of action and effects on splanchnic blood flow. However, specific guidance on which is the optimal vasoactive drug to use in these settings is limited. This systematic review aimed to evaluate the current evidence comparing vasoactive drugs in AMI. Methods: A systematic search of Ovid Medline, Ovid Embase, Cochrane CENTRAL and the Cochrane Database of Systematic Review was performed on the 5th of November 2020 to identify randomised clinical trials comparing different vasoactive agents in AMI on outcomes including mortality. The search was performed through the Royal College of Surgeons of England (RCSEng) search support library. Results were analysed using the Rayyan platform, and independently screened by four investigators. Results: 614 distinct papers were identified. After screening, there were no randomised clinical trials meeting the inclusion criteria. Conclusions: This review identifies a gap in literature, and therefore recommends an investigation into current practice and clinician preference in relation to vasoactive agents in AMI. Multicentre randomised controlled trials comparing these medications on clinical outcomes will therefore be required to address this question.

Hidden Fluids in Plain Sight: Identifying Intravenous Medication Classes as Contributors to Intensive Care Unit Fluid Intake

Introduction: Fluid stewardship targets optimal fluid management to improve patient outcomes. Intravenous (IV) medications, flushes, and blood products, collectively referred to as hidden fluids, contribute to fluid intake in the intensive care unit (ICU). The impact of specific IV medications on fluid intake is unknown. Objective: Characterize IV medication classes based on contribution to ICU fluid intake by frequency of administration and total volume infused to identify targets for fluid stewardship. Methods: This multi-center, retrospective nested cohort study included patients admitted to a medical or surgical ICU between January 2017 and December 2018. The primary outcome was to identify the volume contribution of specific IV medication classes administered over the first 3 ICU days. Secondary outcomes were the administration frequency of these medications and their proportion of total daily volume intake over the first 3 ICU days. Results: The study included 210 patients. The largest mean administration volumes over the course of the first 3 ICU days were attributed to antibacterials (968 ± 846 mL), vitamins/minerals/electrolytes (416 ± 935 mL), pain/agitation/delirium agents (310 ± 512 mL), and vasoactive agents (282 ± 744 mL). The highest frequencies over the course of the first 3 ICU days were attributed to antibacterials (n = 180; 86%), pain/agitation/delirium agents (n = 143; 68%), vitamins/minerals/electrolytes (n = 123; 59%), and vasoactive agents (n = 96; 46%). IV medications contributed 2601 ± 2573 mL of fluid volume per patient over the first 3 ICU days, accounting for 42% ± 29% of overall volume. Conclusion: IV medications contribute over 40% of total fluid intake within the first 3 days of ICU admission, with antibacterials as top contributors by administration volume and frequency. Future research implementing fluid stewardship to ICU fluid sources, such as concentrating IV medications, switching IV medications to oral formulations, de-escalation of antibacterials, and reduction of maintenance fluids, should be performed to minimize hidden fluids from IV medications.