The pressure field as a methodology for fluid management and red cell preservation during cardiac surgery.

PURPOSE: Anemia and red cell transfusion contribute to morbidity and mortality of surgery. The concept of patient blood management to mitigate preoperative anemia, optimize coagulation, conserve red cells intraoperatively and accept lower post-operative transfusion thresholds has recently gained widespread acceptance across a range of surgical disciplines. Fluid administration is likely to contribute significantly to perioperative anemia and red-cell transfusion requirements, yet a robust basis for managing fluid administration in this context has not been articulated. There is an urgent need for this. METHODS: We developed 'the pressure field method' as a novel approach to guiding the administration of fluid and drugs to optimize tissue perfusion. The pressure field method was used for the intraoperative management of 67 patients undergoing semi-elective cardiac surgery. We compared intraoperative anemia and transfusion requirements in this cohort with a conventional group of 413 patients undergoing cardiac surgery. RESULTS: In the pressure field group, no patients required transfusion whereas in the conventional group, 16% required transfusion during bypass and these patients received an average of 2.4 units of packed red cells (P < 0.0001). The average decrease in hemoglobin in the pressure field group was only 13 g/L, whereas in the conventional group it was 52 g/L (P < 0.0001). 80% of the pressure field group received no intravenous fluid during cardiac surgery, and the average intraoperative fluid load was 115 mL. CONCLUSION: The pressure field method appears to reduce transfusion requirements due to decreased intraoperative fluid loading.

Significant venous flow alterations following brain arteriovenous malformation Surgery: Assessment by transcranial colour duplex.

Brain arteriovenous malformation (bAVM) resection imposes several post-operative clinical challenges including intracranial haemorrhage (ICH). Daily non-invasive monitoring of haemodynamic measurements may be useful in predicting post-operative ICH. This prospective study used transcranial colour duplex (TCCD) and central aortic pressure (CAP) measurements to evaluate 15 bAVM patients pre-operatively and daily ≤ 14 days post-operatively. TCCD measurements of middle cerebral artery and veins included peak systolic (PSV), end diastolic (EDV), and pulsatility indices (PI). Parameters were compared with 7 craniotomy patients (non-bAVM craniotomy/surgical group). Normal reference values included 20 healthy volunteers. Significant middle cerebral vein MCV changes in bAVM patients occurred; Maximal PSV was significantly higher (median 47 cm/s) compared to non-bAVM craniotomy/surgical controls (median 17 cm/s, p = 0.0123); maximal PI was significantly higher (median 0.99, p = 0.005) compared to the non-bAVM craniotomy/surgical controls (median 0.49). In 8 of 15 patients, increased MCV velocity and pulsatility "stabilised" within 14 days post-operatively. Mean number of days for the 8 patients to reach stable state was 5.9 days, (range 0-9 days). To our knowledge, this is the first imaging study demonstrating significant venous changes post bAVM resection. Significant increased venous flow occurs in pial veins bilaterally. Increased pressure of venous flow is evidenced by a significant increase in diameter and pulsatility. Subsequently, haemorrhagic complications may be due distal constriction of the pial veins causing venous hypertension. The cause of the dilated vascular bed is unknown.

Disparate Associations of 24-h Central Aortic and Brachial Cuff Blood Pressure With Hypertension-Mediated Organ Damage and Cardiovascular Risk.

Objective: Aim of this study was to evaluate the associations of non-invasive central aortic and peripheral (brachial) blood pressure (BP) for Hypertension-mediated organ damage (HMOD) and atherosclerotic cardiovascular disease (ASCVD) risk. Methods: We evaluated associations of HMOD with 24-h ambulatory blood pressure monitoring (ABPM) of central aortic and peripheral BP indices in patients with primary hypertension and presence of several cardiovascular risk factors. BP measurements were performed by means of a non-invasive automated oscillometric device (Mobil-O-Graph). HMOD was defined as the presence of carotid intima-media thickness (IMT) above normal values and/or carotid plaque, left ventricular hypertrophy (LVH), and/or renal abnormalities as assessed by urine albumin/creatinine ratio above normal values and/or estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m2. Results: In the study cohort of 273 (age 55.2 ± 13.4 years, 71.8% male) patients with primary hypertension, documented HMOD was present in 180 (65.9%), LVH in 70 (25.6%), increased IMT in 129 (47.3%). Fifty-six patients (20.5%) had kidney organ damage (20.5% albuminuria and 2.6% impaired eGFR). When accounting for confounding factors (age, sex, body-mass-index, antihypertensive treatment, smoking, triacylglycerol, statin treatment, glucose, hypoglycemic therapy, or heart rate) only peripheral 24-h pulse pressure (PP) maintained statistical significance with HMOD indices (OR: 1.126, 95% CI: 1.012~1.253; p = 0.029). Using ASCVD risk score as the independent continuous variable in multiple linear regression, 24-h central systolic pressure (SBP) (ß = 0.179; 95% CI:0.019~0.387; p = 0.031), daytime central PP (ß = 0.114; 95% CI:0.070~0.375; p = 0.005, night-time central SBP (ß = 0.411; 95% CI:0.112~0.691; p = 0.007) and night-time PP (ß = 0.257; 95% CI:0.165~0.780; p = 0.003) were all positively associated with ASCVD risk. Conclusions: Blood pressure obtained by 24-h ABPM was better correlated with HMOD than office BP. Whilst 24-h peripheral BP showed a stronger association with HMOD than 24-h central BP, the prognostic value of 24-h central BP for the 10-year ASCVD risk was superior to 24-h peripheral BP.

Central aortic pressure improves prediction of cardiovascular events compared to peripheral blood pressure in short-term follow-up of a hypertensive cohort.

Objective: The aim of this study was to assess indices of a comprehensive panel of central aortic pressure and arterial stiffness for prediction of cardiovascular events in a hypertensive cohort.Methods: Noninvasive measurements of central aortic blood pressure, brachial pressure, wave reflection augmentation index, pressure amplification, pulse wave velocity (PWV) and carotid intima-media thickness (IMT) were obtained in 675 hypertensive patients (age 61 ± 9 years, 425 males) for a mean follow-up period 25 ± 4 months. The primary endpoints were defined as cardiovascular disease (CVD) events or death from CVD.Results: After adjusting for confounding factors, central systolic (cSBP) and pulse pressure (cPP) showed higher hazard ratios (HR/10 mmHg) for cardiovascular events (CV) compared to peripheral pressure indices (pSBP, pPP) at age >60 years (cSBP: HR = 1.18, pSBP: HR = 1.17, p = 0.034; cPP: HR = 1.28, pPP: HR = 1.2, p = 0.019). Each SD increase in IMT and in central augmented pressure (cAP) entailed a 1.4 times higher risk of increased total events in elderly patients (age >60 years). For males, each SD increase in cAP was associated with 1.36 times higher risk of increased total events. For females, each SD increase in cAIx and cAP was associated with 0.4 and 0.5 times lower risk of increased total and major CV, respectively. This sex difference is most likely due to lack of age-related increase of cAIx in females after age >60 years compared to males.Conclusions: Central pressure improved prediction of CVD compared to peripheral pressure during a relatively short-term follow up of approximately 2 years at age >60 years.

Impact of new hypertension guidelines on target organ damage screening in a Shanghai community-dwelling population.

Recently, the 2017 ACC/AHA released new hypertension guidelines and proposed a redefinition of hypertension from 140/90 to 130/80 mm Hg. This study assesses the impact of the lower threshold for hypertension diagnosis on the association of hypertension with target organ damage (TOD). Health checks were conducted in a community-dwelling population in Shanghai in 2017 (N = 10 826; 43.26% mean, age 62 ± 12 years [range 29-95 years]). Subclinical TOD indices were quantified in terms of left ventricular hypertrophy (LVH) by electrocardiogram (Sokolow-Lyon standard), estimated glomerular filtration rate (eGFR), and presence of proteinuria. Information on clinical TOD was obtained by questionnaire. Arteriosclerotic cardiovascular disease (ASCVD) was determined by the 2013 ACC/ AHA recommended guidelines. Compared to the higher threshold (140/90 mm Hg), the lower threshold (130/80 mm Hg) was associated with variable rates of increased detection of hypertension and TOD: (a) Hypertension: incidence of hypertension, 29.5% (51.8%-81.5%) increase in persons with hypertension if the threshold of 130/80 mm Hg is used; (b) Subclinical TOD: LVH, 20.8%; eGFR (30-60 mL/min per 1.73 m2 ), 23.7%; proteinuria, 23.5%; (c) Clinical TOD: chronic kidney disease (CKD) IV (eGFR＜30 mL/min per 1.73 m2 ), 3.1%; diabetes (fasting glucose ≥7.0 mmol/L or HbA1C＞7.0%), 24.3%; stroke, 26.4%; chronic heart disease, 28.1%; acute myocardial infarction, 19.5% (69.4% to 88.9% of total of 36); ASCVD ≥10%, 29.3%. The lower threshold was associated with a significantly higher detection rate of clinical and subclinical TOD of approximately 20% compared to the higher threshold. 15%-20% of TOD and 29% of ASCVD were also found below the lower threshold of hypertension.

Intereye comparison of femtosecond laser-assisted cataract surgery capsulotomy and manual capsulorhexis edge strength.

PURPOSE: To compare the breaking force required to tear the explanted capsule after femtosecond laser-assisted cataract surgery in the worse eye and manual cataract surgery in the contralateral eye. SETTING: Personaleyes, Sydney, Australia. DESIGN: Prospective nonrandomized case study. METHOD: Patients with bilateral cataract had femtosecond laser-assisted cataract surgery with the Lensx laser in the eye with worse vision and manual cataract surgery in the contralateral eye. Each explanted capsule was stretched mechanically, and the breaking force and strain in grams (g) were compared. When a large contralateral difference in capsule strength was found, scanning electron microscopy (SEM) was applied to determine whether morphologic imperfections were present in a case with a weak capsule. RESULTS: Paired samples of 78 eyes of 39 patients were tested. The mean breaking force was not significantly different between manual capsulorhexes (2.3 g ± 2.0 [SD]) and femtosecond laser capsulotomies (2.0 ± 2.2 g, P = .52). The breaking strain for the manual samples (33.8% ± 18.3%) and for the femtosecond laser samples (34.6% ± 18.6%) were also not significantly different (P = .81). In 5 patients, in the femtosecond group, the capsules required considerably less force to break than the capsules in the manual group. However, the SEM images of these samples did not show specific laser imperfections. CONCLUSION: In paired human eyes, the capsulotomies created by a femtosecond laser with a contact lens interface were as strong as manual capsulorhexes.

Tissue Transglutaminase Modulates Vascular Stiffness and Function Through Crosslinking-Dependent and Crosslinking-Independent Functions.

BACKGROUND: The structural elements of the vascular wall, namely, extracellular matrix and smooth muscle cells (SMCs), contribute to the overall stiffness of the vessel. In this study, we examined the crosslinking-dependent and crosslinking-independent roles of tissue transglutaminase (TG2) in vascular function and stiffness. METHODS AND RESULTS: SMCs were isolated from the aortae of TG2-/- and wild-type (WT) mice. Cell adhesion was examined by using electrical cell-substrate impedance sensing and PicoGreen assay. Cell motility was examined using a Boyden chamber assay. Cell proliferation was examined by electrical cell-substrate impedance sensing and EdU incorporation assays. Cell micromechanics were studied using magnetic torsion cytometry and spontaneous nanobead tracer motions. Aortic mechanics were examined by tensile testing. Vasoreactivity was studied by wire myography. SMCs from TG2-/- mice had delayed adhesion, reduced motility, and accelerated de-adhesion and proliferation rates compared with those from WT. TG2-/- SMCs were stiffer and displayed fewer cytoskeletal remodeling events than WT. Collagen assembly was delayed in TG2-/- SMCs and recovered with adenoviral transduction of TG2. Aortic rings from TG2-/- mice were less stiff than those from WT; stiffness was partly recovered by incubation with guinea pig liver TG2 independent of crosslinking function. TG2-/- rings showed augmented response to phenylephrine-mediated vasoconstriction when compared with WT. In human coronary arteries, vascular media and plaque, high abundance of fibronectin expression, and colocalization with TG2 were observed. CONCLUSIONS: TG2 modulates vascular function/tone by altering SMC contractility independent of its crosslinking function and contributes to vascular stiffness by regulating SMC proliferation and matrix remodeling.

Long-Term Angiotensin II Receptor Blockade Limits Hypertension, Aortic Dysfunction, and Structural Remodeling in a Rat Model of Chronic Kidney Disease.

BACKGROUND/AIMS: Chronic kidney disease (CKD) is associated with large artery remodeling, endothelial dysfunction and calcification, with angiotensin II (Ang II) a known driver of these pathologies. We investigated long-term Ang II type 1 receptor inhibition with valsartan on aortic function and structure in the Lewis polycystic kidney (LPK) rat model of CKD. METHODS: Mixed sex LPK and Lewis control (total n = 28) treated (valsartan 60 mg/kg/day p.o. from 4 to 18 weeks) and vehicle groups were studied. Functional responses to noradrenaline (NA), potassium chloride and endothelium-dependent and independent relaxations were investigated in vitro using acetylcholine hydrochloride (ACh) and sodium nitroprusside (SNP), respectively. Effects of the nitric oxide synthase (NOS) substrate L-arginine, NOS inhibitor L-NAME and cyclooxygenase inhibitor indomethacin on ACh responses were examined. RESULTS: In the LPK, valsartan reduced systolic blood pressure and urinary protein, ameliorated exaggerated sensitivity to NA, and normalized endothelium-dependent (ACh-Rmax; 91 ± 7 vs. 59 ± 6%, p = 0.0001) and independent dysfunction (SNP-Rmax; 99 ± 1 vs. 82 ± 7%, p = 0.040), as well as improving NO-dependent relaxation (Rmax; -51 ± 6 vs. -26 ± 9%, p = 0.008). Valsartan also reduced aortic wall hypertrophy, elastin disruption/fragmentation, calcification, media cystic degeneration, and levels of matrix metalloproteinase 9. CONCLUSIONS: This study highlights the role of Ang II in driving vascular manifestations of CKD and indicates that early treatment can significantly limit pathological changes.

Central blood pressure, arterial waveform analysis, and vascular risk factors in glaucoma.

PURPOSE: Reduced ocular perfusion pressure has been linked to glaucoma, and increased arterial stiffness is implicated in systemic cardiovascular risk. This study measured central blood pressure (BP) and arterial waveforms derived from pulse tonometry, together with data on systemic and ocular vascular factors relevant to glaucoma status. METHODS: A total of 126 patients and 66 normal controls were tested, including 90 primary open-angle glaucoma (POAG) patients and 36 normal tension glaucoma (NTG) patients. Glaucoma patients had been followed for at least 3 years and inclusion required several (>4) reliable visual fields such that glaucoma progression could be determined. Radial pulse tonometry and brachial BP data were collected, together with data on disc hemorrhages, spontaneous venous pulsation, peripapillary atrophy, smoking, and medications. RESULTS: Brachial BP or derived central aortic BP parameters generally showed no significant differences between glaucoma patients and normal individuals. The POAG group had a lower pulse pressure, which was also significant in the regression analysis (P<0.002). In the arterial waveform analysis, POAG was associated with a lower brachial form factor than NTG (P<0.001) and higher subendocardial viability ratio (P<0.008). NTG was associated with a lower body mass index, and POAG with a smoking history. There was an increased incidence of disc hemorrhages and a reduced incidence of spontaneous venous pulsations in the progressing group. CONCLUSIONS: Derived central BP does not reveal significant differences from controls or in glaucoma subgroups, but a reduced pulse pressure was identified. There may be some changes in arterial pulse waveform shape suggesting possible differences in diastolic perfusion. Disc hemorrhages and loss of spontaneous venous pulsation were associated with disease progression.