Retinal vessel diameter changes induced by transient high perfusion pressure

·AIM: To investigate the effects of transient high perfusion pressure on the retinal vessel diameter and retinal ganglion cells.·METHODS: The animals were divided into four groups according to different infusion pressure and infusion time(60 mm Hg-3min, 60 mm Hg-5min, 100 mm Hg-3min, 100 mm Hg-5min). Each group consisted of six rabbits. The left eye was used as the experimental eye and the right as a control. Retinal vascular diameters were evaluated before, during infusion, immediately after infusion, 5min, 10 min and 30 min after infusion based on the fundus photographs. Blood pressure was monitored during infusion. The eyes were removed after 24 h.Damage to retinal ganglion cell(RGC) was analyzed by histology.·RESULTS: Retina became whiten and papilla optic was pale during perfusion. Measurements showed significant decrease in retinal artery and vein diameter during perfusion in all of the four groups at the proximal of the edge of the optic disc. The changes were significant in the 100 mm Hg-3min group and 100 mm Hg-5min group compared with 60 mm Hg-3min group(P 1=0.025, P 2=0.000).The diameters in all the groups recovered completely after 30 min of reperfusion. The number of RGC)showed no significant changes at the IOP in 100 mm Hg with5 min compared with contralateral untreated eye(P 】0.05).·CONCLUSION: Transient fluctuations during infusion lead to temporal changes of retinal vessels, which could affect the retinal blood circulation. The RGCs were not affected by this transient fluctuation. Further studies are necessary to evaluate the effect of pressure during realtime phacoemusification on retinal blood circulation.

Association between Mean Ocular Perfusion Pressure and Diabetic Retinopathy in a Northeastern Chinese Population

Objective To evaluate the association between diabetic retinopathy(DR) and mean ocular perfusion pressure(MOPP) in patients with type 2 diabetes mellitus(T2 DM).Methods Patients from the Fushun Diabetic Retinopathy Cohort Study(FS-DIRECT), a communitybased prospective cohort study conducted in northeast China, were included in this study. The presence and severity of DR were determined by grading fundus photographs according to the Early Treatment Diabetic Retinopathy Study(ETDRS) retinopathy scale. Systolic and diastolic blood pressure(SBP and DBP) were recorded using an electronic sphygmomanometer. Intraocular pressure(IOP) was measured using an iCare rebound tonometer. MOPP was calculated using the formula MOPP = 2/3 [DBP + 1/3(SBP-DBP)]-IOP.Results In total, 1,857 patients who had gradable fundus photography and MOPP data were enrolled in this study. Male patients had a higher MOPP than female patients(52.25 ± 8.75 vs. 50.96 ± 8.74 mmHg, P = 0.002). Overall, both male and female patients with any type of DR, non-proliferative DR(NPDR), or non-sight-threatening DR(non-STDR) had significantly higher MOPP relative to patients without DR. Increased MOPP(per 1 mmHg) was in turn associated with the presence of any type of DR[odds ratio(OR) = 1.03, 95% confidence interval(CI) : 1.02–1.04], NPDR(OR = 1.03 95% CI: 1.02–1.04),and non-STDR(OR = 1.03, 95% CI: 1.01–1.04) after adjusting for confounders. Increased MOPP(per 1 mmHg) was also associated with an increased likelihood of macular edema(OR = 1.02, 95% CI:1.01–1.04).Conclusions The results suggest that increased MOPP was associated with DR and macular edema in northeastern Chinese patients with T2 DM.

Paracentesis following intravitreal drug injections in maintaining physiologic ocular perfusion pressure

A retrospective analysis was performed of patients who received a paracentesis immediately following an intravitreal injection of bevacizumab or triamcinolone acetonide.These patients were previously diagnosed as having glaucoma,ocular hypertension,or had responded previously with sustained elevated intraocular pressure.Of 1661 procedures were performed.Totally 219（13%） of the injections were on phakic patients.A median（SD） of 210 μL（40 μL） of aqueous was removed during each paracentesis.There were no reported incidences of any complications.We propose performing a paracentesis immediately following intravitreal injections for patients at risk for ocular hypertension,glaucoma,and retinal vein or artery occlusion.

CBF/CBV maps in normal volunteers studied with ^(15)O PET:a possible index of cerebral perfusion pressure

Local cerebral perfusion pressure （CPP） is a primary factor controlling cerebral circulation and previous studies have indicated that the ratio of cerebral blood flow （CBF） to cerebral blood volume （CBV） can be used as an index of the local CPP. In this study, we investigated whether the CBF/CBV ratio differs among different brain structures under physiological conditions, by means of （15）O positron emission tomography. Nine healthy volunteers （5 men and 4 women; mean age, 47.0 ± 1.2 years） were studied by H2（15）O bolus injection for CBF measurement and by C（15）O inhalation for CBV measurement. The CBF/CBV ratio maps were created by dividing the CBF images by the CBV images after anatomical normalization. Regions of interest were placed on the CBF/CBV maps and comparing the regions. The mean CBF/ CBV ratio was highest in the cerebellum （19.3 ＋ 5.2/ min）, followed by the putamen （18.2 ± 3.9）, pons （16.4 ±4.6）, thalamus （14.5：1： 3.3）, cerebral cortices （13.2 ±2.4）, and centrum semiovale （1115 ± 2.1）. The cerebellum and putamen showed significantly higher CBF/CBV ratios than the cerebral cortices and centrum semiovale. We created maps of the CBF/ CBV ratio in normal volunteers and demonstrated higher CBF/CBV ratios in the cerebellum and putamen than in the cerebral cortices and deep cerebral white matter. The CBF/CBV may reflect the local CPP and should be studied in hemodynamicallycompromised patients and in patients with risk factors for small-artery diseases of the brain. Keywords： cerebral perfusion pressure; cerebra blood flow; cerebral blood volume; H2（15）O; C（15）O

Lin28B Expression in Reduced Uterine Perfusion Pressure Rat Model

Objective:Preeclampsia(PE)is a serious complication of pregnancy.Placental ischemia could be an initiating event,but the molecular mechanisms underlying PE are unclear.Lin28B,a paralog of Lin28 RNA-binding protein,is predominantly expressed in human placenta,and decreased Lin28B expression may play a role in PE by reducing trophoblast invasion.The current study was intended to verify whether Lin28B plays a role in the pathogenesis of PE in rat model for reduced uterine perfusion pressure(RUPP).Methods:We used RUPP rat model.The changes in blood pressure,24-h urine protein excretion,and fetal development in RUPP rats were recorded and compared to those of normal pregnant(NP)rats.Furthermore,the expression of Lin28B mRNA and protein in placenta was determined using quantitative real-time polymerase chain reaction,Western blotting,and immunohistochemistry.Results:The blood pressure,24-h urine protein excretion,and embryo absorption rate were significantly increased in RUPP rats on the 20^(th) day of gestational period compared with the NP rats(P<0.001).However,there was no difference in the weight of placenta in RUPP versus NP rats(P>0.05).The expression levels of Lin28B mRNA and protein in the placenta of RUPP rats were also significantly decreased in comparison to NP rats(P<0.001).Conclusion:Our results show that the expression of Lin28B in the placenta of RUPP rats is different from that in NP rats,thus suggesting a role of Lin28B in the pathogenesis of preeclampsia.

Elevated intra-abdominal pressure:A review of current knowledge

Elevated intra-abdominal pressure(IAP)is a known cause of increased morbidity and mortality among critically ill patients.Intra-abdominal hypertension(IAH)and abdominal compartment syndrome can lead to rapid deterioration of organ function and the development of multiple organ failure.Raised IAP affects every system and main organ in the human body.Even marginally sustained IAH results in malperfusion and may disrupt the process of recovery.Yet,despite being so common,this potentially lethal condition often goes unnoticed.In 2004,the World Society of the Abdominal Compartment Syndrome,an international multidisciplinary consensus group,was formed to provide unified definitions,improve understanding and promote research in this field.Simple,reliable and nearly costless standardized methods of non-invasive measurement and monitoring of bladder pressure allow early recognition of IAH and timely optimized management.The correct,structured approach to treatment can have a striking effect and fully restore homeostasis.In recent years,significant progress has been made in this area with the contribution of surgeons,internal medicine specialists and anesthesiologists.Our review focuses on recent advances in order to present the complex underlying pathophysiology and guidelines concerning diagnosis,monitoring and treatment of this life-threatening condition.

Unveiling the silent link:Normal-tension glaucoma's enigmatic bond with cardiac blood flow

This comprehensive review embarks on a captivating journey into the complex relationship between cardiology and normal-tension glaucoma(NTG),a condition that continues to baffle clinicians and researchers alike.NTG,characterized by optic nerve damage and visual field loss despite normal intraocular pressure,has long puzzled clinicians.One emerging perspective suggests that alterations in ocular blood flow,particularly within the optic nerve head,may play a pivotal role in its pathogenesis.While NTG shares commonalities with its high-tension counterpart,its unique pathogenesis and potential ties to cardiovascular health make it a fascinating subject of exploration.It navigates through the complex web of vascular dysregulation,blood pressure and perfusion pressure,neurovascular coupling,and oxidative stress,seeking to uncover the hidden threads that tie the heart and eyes together in NTG.This review explores into the intricate mechanisms connecting cardiovascular factors to NTG,shedding light on how cardiac dynamics can influence ocular health,particularly in cases where intraocular pressure remains within the normal range.NTG's enigmatic nature,often characterized by seemingly contradictory risk factors and clinical profiles,underscores the need for a holistic approach to patient care.Drawing parallels to cardiac health,we examine into the shared vascular terrain connecting the heart and the eyes.Cardiovascular factors,including systemic blood flow,endothelial dysfunction,and microcirculatory anomalies,may exert a profound influence on ocular perfusion,impacting the delicate balance within the optic nerve head.By elucidating the subtle clues and potential associations between cardiology and NTG,this review invites clinicians to consider a broader perspective in their evaluation and management of this elusive condition.As the understanding of these connections evolves,so too may the prospects for early diagnosis and tailored interventions,ultimately enhancing the quality of life for those living with NTG.

Should we perform decompressive laparotomy during severe acute pancreatitis with intra-abdominal hypertension below 25 mmHg:Only the gut knows

We suggest that during severe acute pancreatitis(SAP)with intra-abdominal hypertension,practitioners should consider decompressive laparotomy,even with intra-abdominal pressure(IAP)below 25 mmHg.Indeed,in this setting,non-occlusive mesenteric ischemia(NOMI)may occur even with IAP below this cutoff and lead to transmural necrosis if abdominal perfusion pressure is not promptly restored.We report our experience of 18 critically ill patients with SAP having undergone decompressive laparotomy of which one third had NOMI while IAP was mostly below 25 mmHg.

Effect of mean arterial pressure change by norepinephrine on peripheral perfusion index in septic shock patients after early resuscitation

Background:The peripheral perfusion index(PI),as a real-time bedside indicator of peripheral tissue perfusion,may be useful for determining mean arterial pressure(MAP)after early resuscitation of septic shock patients.The aim of this study was to explore the response of PI to norepinephrine(NE)-induced changes in MAP.Methods:Twenty septic shock patients with pulse-induced contour cardiac output catheter,who had usual MAP under NE infusion after early resuscitation,were enrolled in this prospective,open-label study.Three MAP levels(usual MAP-10 mmHg,usual MAP,and usual MAP+10 mmHg)were obtained by NE titration,and the corresponding global hemodynamic parameters and PI were recorded.The general linear model with repeated measures was used for analysis of variance of related parameters at three MAP levels.Results:With increasing NE infusion,significant changes were found in MAP(F=502.46,P<0.001)and central venous pressure(F=27.45,P<0.001)during NE titration.However,there was not a significant and consistent change in continuous cardiac output(CO)(F=0.41,P=0.720)and PI(F=0.73,P=0.482)at different MAP levels.Of the 20 patients enrolled,seven reached the maximum PI value at usual MAP-10 mmHg,three reached the maximum PI value at usual MAP,and ten reached the maximum PI value at usual MAP+10 mmHg.The change in PI was not significantly correlated with the change in CO(r=0.260,P=0.269)from usual MAP-10 mmHg to usual MAP.There was also no significant correlation between the change in PI and change in CO(r=0.084,P=0.726)from usual MAP to usual MAP+10 mmHg.Conclusions:Differing MAP levels by NE infusion induced diverse PI responses in septic shock patients,and these PI responses may be independent of the change in CO.PI may have potential applications for MAP optimization based on changes in peripheral tissue perfusion.

Hypoperfusion assessed by pressure reactivity index is associated with delayed cerebral ischemia after subarachnoid hemorrhage:an observational study

Background:Dysfunction of cerebral autoregulation is one of the pathophysiological mechanisms that causes delayed cerebral ischemia(DCI)after subarachnoid hemorrhage(SAH).Pressure reactivity index(PRx)have been confirmed to reflect the level of cerebral autoregulation and used to derive optimal cerebral perfusion pressure(CPPopt).The goal of this study is to explore the associations between autoregulation,CPPopt,PRx,and DCI.Methods:Continuous intracranial pressure(ICP),arterial blood pressure(ABP),and cerebral perfusion pressure(CPP)signals acquired from 61 aSAH patients were retrospectively analyzed.PRx was calculated and collected by Pneumatic computer system.The CPP at the lowest PRx was determined as the CPPopt.The duration of a hypoperfusion event(dHP)was defined as the cumulative time that the PRx was>0.3 and the CPP was<CPPopt.The duration of CPP more than 10 mmHg below CPPopt(ΔCPPopt<−10 mmHg)was also used to assess hypoperfusion.The percent of the time of hypoperfusion by dHP andΔCPPopt<−10 mmHg(%dHP and%ΔCPPopt)were compared between DCI group and control group,utilizing univariate and multivariable logistic regression.It was the clinical prognosis at 3 months after hemorrhage that was assessed with the modified Rankin Scale,and logistic regression and ROC analysis were used for predictive power for unfavorable outcomes(mRs 3–5).Results:Data from 52 patients were included in the final analysis of 61 patients.The mean%dHP in DCI was 29.23%and 10.66%in control.The mean%ΔCPPopt<−10 mmHg was 22.28%,and 5.90%in control.The%dHP(p<0.001)and the%ΔCPPopt<−10mmHg(p<0.001)was significantly longer in the DCI group.In multivariate logistic regression model,%ΔCPPopt<−10 mmHg(p<0.001)and%dHP(p<0.001)were independent risk factor for predicting DCI,and%ΔCPPopt<−10 mmHg(p=0.010)and%dHP(p=0.026)were independent risk factor for predicting unfavorable outcomes.Conclusions:The increase of duration of hypoperfusion events and duration of CPP below CPPopt over 10 mmHg,evaluated as time of lowered CPP,is highly indicative of DCI and unfavorable outcomes.

Hemodynamic Profiling Using a Cardiac Index–Systemic Vascular Resistance Plot in Patients with Fontan Circulation

Background: Elevated Fontan pressure (FP) alone cannot fully predict clinical outcomes. We hypothesized thathemodynamic profiling using a cardiac index (CI)-systemic vascular resistance (SVR) plot could characterize clinicalfeatures and predict the prognosis of post-Fontan patients. Methods: We included post-Fontan patients whounderwent cardiac catheterization at age < 10 years. Patients were classified into four categories: A, CI ≥ 3, SVRindex (SVRI) ≥ 20;B, CI < 3, SVRI ≥ 20;C, CI ≥ 3, SVRI < 20;and D, CI < 3, SVRI < 20. The primary outcome wasfreedom from the combined endpoint: new onset of protein-losing enteropathy or plastic bronchitis, heart transplant,and death. Clinical and hemodynamic variables and freedom from the endpoint were compared betweenthe hemodynamic categories and outcome predictors were evaluated. Results: Eighty-three patients wereincluded. Median follow-up was 5.3 years. Category A/B/C/D consisted of 4/15/53/11 patients, respectively. Allthe patients in category A were New York Heart Association I/II and had a significantly lower pulmonary vascularresistance index (PVRI). Patients in category C had lower pulmonary/systemic blood flow. Patients in category Dhad a higher PVRI and had the poorest freedom from the endpoint (44% at 5 years). Elevated FP and category Dwere outcome predictors. Conclusions: CI-SVR plots was a novel adjunctive method for Fontan hemodynamicprofiling.

Effect of Different Drugs on End-tidal Carbon Dioxide during Rodent CPR

The purpose of this study was to investigate the effect of nonadrenergic agents on cardiopulmonary resuscitation (CPR) and end-tidal CO2(ETCO2)during CPR in a rodent model. Our results suggested that: 1) coronary perfusion pressure (CPP) after drugs infusion was increased significantly by methoxamine, arginine vasopresin (AVP) and angiotension- Ⅱ(ANG- Ⅱ), but not by endothelin-1 (ET-1): 2) ETCO2 prior to defibrillation was decreased significantly by a pure a1 adrenergic agents,methoxamine and were increased significantly by non-adrenergic agents, ANG-Ⅱ and ET-1 during rodent CPR;3) a significant positive correlation between ETCO2 and CPP was observed in AVP group, suggesting that AVP have little effect on pulmonary circulation; and 4) methoxamine, AVP and ANG-Ⅱ have similar effect on resuscitability during rodent CPR.

Resuscitation from Prolonged Ventricular Fibrillation by Epinephrine Combined with Sodium-Hydrogen Exchanger Isoform-1 Inhibitor Cariporide

Objective To test the resuscitative effects from prolonged ventricular fibrillation by epinephrine combined with sodium hydrogen exchanger isoform 1 inhibitor Cariporide. Methods 16 rats were received a 3 mg/kg bolus of Cariporide or the same volume of 0.9%NaCl solution (control) 15 seconds before completion 12 minutes untreated VF. Chest compression (CC) was started for a total of 8 minutes. Adjusted the depth of compressor so that the aortic diastolic pressure to 25～28 mmHg during the 2nd minute of CC. Fix the depth of the piston and this depth was used throughout the remaining 6 minutes of CC. 10 seconds before starting the 3rd minute of chest compression, injected epinephrine (30 μg/kg). Recorded the time at which restoration of spontaneous circulation (ROSC) occurred in Cariporide treated rats. Electrical defibrillation was timed in control group to match the time of spontaneous defibrillation in Cariporide treated rats. To the rats, which cant be defibrillated spontaneously, received chest compression and rescues electrical shocks. Results compared with control group, with the same CC depth, Cariporide treated rats received the higher and longer lasting coronary perfusion pressure (P< 0.05), higher resuscitative rate (P< 0.05), less post resuscitative ventricular ectopic activities (P< 0.001), better hemodynamic effects and longer survival time (P< 0.05). Conclusion Epinephrine combined with sodium hydrogen exchanger isoform 1 inhibitor Cariporide may represent a novel and remarkably effective intervention for resuscitation from prolonged VF.

A New Technique for The Therapy of Complicated Deep Tissue Infection(with 4 Cases)

Objective: The objective of this study was to discuss the effect of double perfusion cannula accompanied with low negative pressure drainage in the treatment of complexity of abdominopelvic and perineal infections. Methods: The technology of the double perfusion cannula accompanied with low negative pressure drainage was used to treat complexity of abdominopelvic and perineal infections. Results: Double perfusion cannula accompanied with low negative pressure drainage can be applied to the treatment of complexity of abdominopelvic and perineal infections. It has an obvious effect on infection control and reduces recovery time. Conclusion: Double perfusion cannula accompanied with low negative pressure drainage has a good effect on complexity of abdominopelvic and perineal infections; it can be used in wider surgical fields to prevent infections.

Modified cold storage of rat livers with self-made HYD solution

Objective To investigate the cold preservation effect on rat livers of a modified storage method with self-made HYD solution.Methods The vascular bed of rat livers was expanded with an additional 20 to 40?ml self-made HYD solution/100?g liver. After resection of the liver, the extra HYD solution (expressed as % liver weight) was entrapped via portal infusion by tying off the supra- and infra-hepatic inferior vena cava. Forty rats were randomly divided into four groups including control group with conventional storage method, and 20%, 30% and 40% groups according to the amount of extra HYD solution. We compared the preservation effect of the modified storage method with that of the conventional storage method using an isolated perfused rat liver model.Results Bile production and all the indices of hepatic microcirculation including portal perfusion pressure, endothelin-1 in the effluent, trypan blue distribution time and histology were significantly superior in the modified method groups compared to those in the control group (P<0.05). The contents of dihydroxybenzoic acid (DHBA) in the modified method groups were significantly lower than those in the control group (P<0.05). Liver enzymes activities in the 30% group were markedly lower than those in the control group (P<0.05). The preservation effect on rat liver in the 30% group was the best among the modified method groups.Conclusion The modified cold storage method is effective and may have potential for clinical application in liver preservation.

Outcome prediction in severe traumatic brain injury with transcranial Doppler ultrasonography

Objective: To investigate the value of transcranial Doppler (TCD) ultrasonography in evaluating the outcome of severe traumatic brain injury and to correlate the TCD values with intracranial pressure (ICP) and cerebral perfusion pressure (CPP) monitoring. Methods: A prospective study was conducted to evaluate the contribution of TCD ultrasonography to neurological outcome in a series of 96 severe traumatic brain injury patients. The quantitative variables of TCD ultrasonography included the mean blood flow velocity of the middle cerebral artery (MCA) and pulsatility index within the first 24 hours of admission. The ICP and CPP values were also recorded. Outcome in 6 months postinjury was evaluated using the Glasgow Outcome Scale (GOS 4 5 was considered as "good" and GOS 1 3 as "poor"). Results: The mean blood flow velocity of the MCA was larger than 40 cm/s in 30 (51%) patients with good outcome whereas it was less than 40 cm/s in 27 (73%) patients with poor outcome (P< 0.025 ). The mean PI in cases of good outcome (34 patients, 57%) was lower than 1.5 whereas in poor outcome (30 patients, 83%) was higher than 1.5 (P< 0.001 ). The correlations of ICP and CPP to pulsatility index were statistically significant (P< 0.01 ). Conclusions: TCD ultrasonography is valid in predicting the patients outcome of 6 months and correlates significantly with ICP and CPP values when it is performed in the first 24 hours of severe traumatic brain injury.

Combination of intraoperative embolization with surgical resection for treatment of giant cerebral arteriovenous malformation

Objective To reduce the risk of surgical resection of giant arteriovenous malformation (AVM) (>6.0 cm) and prevent normal perfusion pressure breakthrough (NPPB) for lowering the postoperative mortality. Methods During the operation under barbiturate anesthesia, the proximal end of the feeding arteries were ligated at first, and 0.5 ml isobutyl 12 cyanoacrylate (IBCA) with 0.5 ml 5% glucose was injected into the vessels towards the AVM, then the malformed vessels were resected totally. Postoperative digital subtraction angiography of the four vessels was performed in all patients. Results 50 patients with giant AVM survived after operation, only 6 (12.0%) had transient neurological dysfunction and 44 (88.0%) recovered after a follow up of 6-36 months. No patient suffered from normal perfusion pressure breakthrough (NPPB). Conclusions The embolization could block the arteriovenous shunts sufficiently to decrease the blood flow away from the normal areas of the brain so as to prevent the incidence of intra and postoperative rebleeding, especially in NPPB. Therefore, the combination of intraoperative embolization with surgical resection is an effective strategy in the treatment of giant cerebral AVMs, which make it operable for those used to be regarded as inoperable cases.

Calcified chronic subdural hematoma: A case report and literature review

Calcified chronic subdural hematoma(CCSDH) is a rare disease that accounts for approximately 0.3%–2.7% of all chronic subdural hematomas(CSDHs). The clinical features of CCSDH are very similar to those of noncalcified CSDH and include headache,decreased alertness,weakness,numbness,gait disturbance,seizures,memory impairment,confusion,and unconsciousness. All symptomatic CCSDH should be treated surgically. Majority of these patients recover well following surgery. In this report,we present the case of a patient with CCSDH who developed severe cerebral edema following its removal,necessitating decompressive craniectomy. Although there were no abnormal findings in laboratory blood tests,and no signs of brain herniation or epilepsy was found the following day after surgery,the patient's family refused all treatment and a post-operative brain computed tomography(CT) scan. The patient was discharged and died at home. Cerebral hematoma and normal perfusion pressure breakthrough(NPPB) may cause severe cerebral edema following the total removal of a CCSDH.