Non-invasive evaluation of cerebral hemodynamic and intracranial pressure in pediatric neuroinfections

The study of intracranial pressure (eICP), cerebral perfusion pressure (eCPP), cerebral blood flow index (CFI), zero flow pressure (ZFP) in 49 children hospitalized in the intensive care unit with severe course of neuroinfections was carried out. The level of consciousness was determined by the Glasgow pediatric scale. Monitoring of central and peripheral hemodynamics (ECG, heart rate, systolic, diastolic and mean blood pressure, and cardiac output), pulse oximetry, capnography, hemoglobin, hematocrit, total protein, urea, creatinine, lactate, glucose and serum electrolytes was done. An ultrasound scanner was used to perform ultrasound duplex scanning of blood flow in the left and middle cerebral artery (MCA), measuring maximum, minimum and average blood flow velocities, pulsation index (PI), and resistance index (RI). Based on the formulae of Edouard et al. indicators of eCPP, ZFP, CFI, eICP were calculated. The eSCP was also determined by the formulae of Kligenchöfer et al. and Bellner et al. All patients were divided into group I with RI > 1.3 and group II with RI < 1.3. It was found that eCPP in the group I was significantly less (29.5 ± 1.3 mm Hg) than in the II group (41.6 ± 1.7 mm Hg). Despite the lack of a reliable difference in blood pressure between groups I and II, the difference in eCPP was found due to a significant difference in eICP 34.6 ± 1.4 and 27.6 ± 0.89 mm Hg in I and II groups respectively. ZFP in group I was significantly higher than in group II. The indexes of the Glasgow coma scale was significantly lower in group I and 7.8 ± 0.6 points. There were observed direct moderate correlations between systolic blood pressure, cardiac output and eSRP and CFI, presumably associated with a loss of autoregulation. CFI in the group I was lower than in the group II. Thus, non-invasive examination of cerebral flow in MCA by duplex sonography revealed that PI > 1.3 is an informative marker of intracranial hypertension and reduction of cerebral perfusion, which is common in children with neuroinfections. To determine the eSRP and CFI it is advisable to use the formula of Edouard et al. and to determine the eICP the formula of Kligenchöfer et al. The obtained data can be useful for objectifying the severity of the condition, predicting the outcomes of neuroinfections, choosing the directions of intensive care and evaluating its effectiveness.

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COMPARISON OF VASOPRESSIN AND PHENYLEPHRINE IN TREATMENT OF DOPAMINE RESISTANT SEPTIC SHOCK – A RANDOMISED CONTROL TRIAL

Asian Journal of Pharmaceutical and Clinical Research ◽

10.22159/ajpcr.2021.v14i1.39977 ◽

2021 ◽

pp. 107-110

Author(s):

MADHUSMITA PATRO ◽

NUPUR MODA ◽

SUSHREE DAS ◽

PRERNA BISWAL

Keyword(s):

Blood Pressure ◽

Septic Shock ◽

Cardiac Output ◽

Intensive Care ◽

Systemic Vascular Resistance ◽

Vascular Resistance ◽

Serum Lactate ◽

Randomised Control Trial ◽

Group I ◽

Group Ii

Objectives: Septic shock is associated with refractory hypotension and organ dysfunction and remains an important cause of mortality in intensive care units (ICUs). Vasopressors are the first-line treatment. The present study aims to compare vasopressin and phenylephrine in the management of dopamine-resistant septic shock in the ICU setting. Methods: The study is a prospective, open-labeled, and randomized study comparing the effects of vasopressin (Group I) and phenylephrine (Group II) in the management of dopamine resistant septic shock in intensive care set up. The parameters recorded from 0 to 6 h after persistent hypotension despite maximum dose of dopamine were: Heart rate (HR) (beats/min), systemic blood pressure (mmHg), cardiac output (L/min), cardiac index (CI) (L/min/m2), stroke volume (ml), systemic vascular resistance index (dynes/cm5/m2), oxygen delivery index (IDO) (ml O2/min/m2), urine output (ml), and serum lactate (mg/dl). Results: There was a significant difference in HR, systolic blood pressure, cardiac output, and CI in both groups from 1 h to 6 h. The IDO had a significant rise in Group II. The serum lactate level also decreased in Group II at 6 h. Conclusion: From our study, we concluded that as organ perfusion and oxygenation are more important for the treatment of septic shock and to keep the vital organs functioning rather than to increase the systemic vascular resistance and blood pressure, phenylephrine showed a better result than vasopressin in the treatment of septic shock.

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Abstract WP432: Non-invasive Respiratory Impedance Enhances Cerebral Perfusion

Stroke ◽

10.1161/str.48.suppl_1.wp432 ◽

2017 ◽

Vol 48 (suppl_1) ◽

Author(s):

Christopher G Favilla ◽

Ashwin B Parthasarathy ◽

John A Detre ◽

Michael T Mullen ◽

Scott E Kasner ◽

...

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Flow Velocity ◽

Cerebral Perfusion ◽

Respiratory Impedance ◽

Mean Flow ◽

Non Invasive ◽

End Tidal ◽

High Level ◽

Mean Flow Velocity

Background: Optimization of cerebral blood flow is the cornerstone of clinical management in a number of neurologic diseases, most notably ischemic stroke. Intra-thoracic pressure influences cardiac output and has the potential to impact cerebral blood flow (CBF). Here we aim to quantify cerebral hemodynamic changes in response to increased respiratory impedance using a non-invasive respiratory device. Methods: Cerebral perfusion was measured under varying levels of respiratory impedance (6cm H 2 0, 9cm H 2 0, and 12 cm H 2 0) in 20 healthy volunteers. Simultaneous measurements of microvascular CBF and middle cerebral artery mean flow velocity (MFV), respectively, were performed with optical diffuse correlation spectroscopy (DCS) and transcranial Doppler ultrasound (TCD). Results: At the high level of respiratory impedance, mean flow velocity increased by 6.4% compared to baseline (p=0.004), but changes in cortical CBF were smaller and non-significant (Figure). Heart rate, cardiac output, respiratory rate, and end tidal CO 2 remained stable during all levels of respiratory impedance. There was small increase in mean arterial blood pressure, 1.7% (p=0.006), at the high level of respiratory impedance. In a multivariable linear regression model accounting for end tidal CO 2 and individual variability, respiratory impedance was associated with increases in both mean flow velocity (coefficient: 0.49, p<0.001) and cortical CBF (coefficient: 0.13, p<0.001). Conclusions: Manipulating intrathoracic pressure via non-invasive respiratory impedance was well tolerated and produced a small but measurable increase in cerebral perfusion in healthy individuals. Future studies in acute ischemic stroke patients with impaired cerebral autoregulation is warranted in order to assess whether respiratory impedance is feasible as a novel non-invasive therapy for stroke.

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3D-ultrasonography for Assessing Endometrial Receptivity to Implantation after Conservative Surgery for Ovarian Endometriomas

Doctor Ru ◽

10.31550/1727-2378-2020-19-8-66-70 ◽

2020 ◽

Vol 19 (8) ◽

pp. 66-70

Author(s):

A.A. Solomatina ◽

◽

A.G. Konoplyannikov ◽

I.Z. Khamzin ◽

O.V. Bratchikova ◽

...

Keyword(s):

Blood Flow ◽

Conservative Surgery ◽

Endometrial Receptivity ◽

Flow Index ◽

Group I ◽

Study Results ◽

Endometrial Volume ◽

Group Ii ◽

3D Ultrasonography ◽

Ovarian Endometriomas

Study Objective: To assess, based on 3D-ultrasonography data, endometrial receptivity to implantation in women who have undergone conservative surgery for ovarian endometriomas (OE). Study Design: This was a prospective, comparative, clinical study. Materials and Methods: One hundred and seventy-two women who had undergone excision of OE were examined in the study: 114 patients with anti-Müllerian hormone (AMH) levels below 1.2 ng/mL (Group I, including subgroup A made up of 44 women younger than 35 and subgroup B made up of 70 women aged 35 to 40) and 58 patients with AMH ≥1.2 ng/mL (Group II). 3D-ultrasonography was performed at six and 12 months after cyst removal (between days 6 and 8 after ovulation). The VOCAL software was used to assess endometrial volume and volumetric blood flow indices, such as vascularization index (VI), flow index (FI), and vascularizationflow index (VFI). Study Results: One year after the surgery, endometrial volume in women from subgroup IA and Group II and volumetric blood flow indices in women from Group II did not significantly differ from population mean values. In subgroup IB endometrial gland volume remained reduced throughout the observation period; hemodynamics did not improve in either the endometrium (VI: 2.39 ± 1.57% after six months and 2.32 ± 1.44% after 12 months) or the subendometrial layer (VI: 10.96 ± 5.68% and 11.86 ± 4.59%, respectively). Conclusion: The structural and hemodynamic abnormalities revealed in the endometrium in the postoperative period should be viewed as factors worsening endometrial receptivity to implantation. Keywords: ovarian endometriosis, endometrial disorders, 3D-ultrasonography, volumetric blood flow indices.

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Comparison of static and dynamic cerebral autoregulation under anesthesia influence in a controlled animal model

PLoS ONE ◽

10.1371/journal.pone.0245291 ◽

2021 ◽

Vol 16 (1) ◽

pp. e0245291

Author(s):

Alexander Ruesch ◽

Deepshikha Acharya ◽

Samantha Schmitt ◽

Jason Yang ◽

Matthew A. Smith ◽

...

Keyword(s):

Blood Pressure ◽

Animal Model ◽

Blood Flow ◽

Intracranial Pressure ◽

Cerebral Perfusion Pressure ◽

Cerebral Autoregulation ◽

Cerebral Perfusion ◽

Perfusion Pressure ◽

Phase Lag ◽

Arterial Blood

The brain’s ability to maintain cerebral blood flow approximately constant despite cerebral perfusion pressure changes is known as cerebral autoregulation (CA) and is governed by vasoconstriction and vasodilation. Cerebral perfusion pressure is defined as the pressure gradient between arterial blood pressure and intracranial pressure. Measuring CA is a challenging task and has created a variety of evaluation methods, which are often categorized as static and dynamic CA assessments. Because CA is quantified as the performance of a regulatory system and no physical ground truth can be measured, conflicting results are reported. The conflict further arises from a lack of healthy volunteer data with respect to cerebral perfusion pressure measurements and the variety of diseases in which CA ability is impaired, including stroke, traumatic brain injury and hydrocephalus. To overcome these differences, we present a healthy non-human primate model in which we can control the ability to autoregulate blood flow through the type of anesthesia (isoflurane vs fentanyl). We show how three different assessment methods can be used to measure CA impairment, and how static and dynamic autoregulation compare under challenges in intracranial pressure and blood pressure. We reconstructed Lassen’s curve for two groups of anesthesia, where only the fentanyl anesthetized group yielded the canonical shape. Cerebral perfusion pressure allowed for the best distinction between the fentanyl and isoflurane anesthetized groups. The autoregulatory response time to induced oscillations in intracranial pressure and blood pressure, measured as the phase lag between intracranial pressure and blood pressure, was able to determine autoregulatory impairment in agreement with static autoregulation. Static and dynamic CA both show impairment in high dose isoflurane anesthesia, while low isoflurane in combination with fentanyl anesthesia maintains CA, offering a repeatable animal model for CA studies.

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PERSONALIZED INTENSIVE CARE OF CARDIOVASCULAR DISORDERS IN CHILDREN WITH RESPIRATORY FAILURE

Ukrainian Scientific Medical Youth Journal ◽

10.32345/usmyj.3(117).2020.46-57 ◽

2020 ◽

Vol 117 (3) ◽

pp. 46-57

Author(s):

Olha Filyk

Keyword(s):

Intensive Care Unit ◽

Intensive Care ◽

Respiratory Failure ◽

Acute Respiratory Failure ◽

Stroke Index ◽

Cardiovascular Dysfunction ◽

Non Invasive ◽

Group I ◽

Hemodynamic Assessment ◽

Group Ii

This article presents data on the frequency of incidence and duration of cardiovascular dysfunction in children with acute respiratory failure. The information on expediency of carrying out of personalized hemodynamic management in case of its insufficiency with use of multiparametric approach to estimate haemodynamic data are presented. The aim of the study was to compare the effectiveness of the standard approach and proposed by us additions to treatment of haemodynamic disorders in children with respiratory failure. It was summarized from the literature reviews that the presence and maintenance of patient`s spontaneous breathing pattern with use of non-invasive estimated cardiovascular monitoring, evaluation of preload with ultrasonography and reassessment of rate and volume of fluid replacement with taking into account solution`s composition might improve treatment results in children with acute respiratory failure. We conducted a prospective single-center non-interventional cohort study in children with acute respiratory failure 1 month - 18 years old. Patients were randomly divided into I and II groups. The data analysis included 43 patients of group I, who received conventional for this intensive care unit monitoring and treatment and 53 patients of group II, in whom we took into account the results of multiparametric monitoring during the correction of hemodynamics.Monitoring of hemodynamics included heart rate, non-invasive systolic, diastolic and mean blood pressure capillary refill time and presence of peripheral arteries pulsation with clinical verification of "warm" or "cold" shock, ScvO2 and lactate levels in the central venous blood; non-invasive estimated monitoring of stroke volume, cardiac output, cardiac index, stroke index using the esCCO technology, NIHON COHDEN (Japan) and the ratio of inferior vena cava diameter at inspiration and exhalation. Hemodynamic support in groups I and II included early goal-directad therapy, individualized and personalized treatment. In II group of patients there were taken into account the dynamics of changes of non-invasive esCCO data about stroke volume, cardiac output, cardiac index and stroke index, cumulative hydrobalance and the ratio of the of inferior vena cava diameter at inspiration and exhalation. Early goal-directed therapy was aimed to (supra) normalize of blood flow and was based on normal hemodynamic data for population, according to percentiles for specific age groups of patients. Individualized hemodynamic therapy included functional hemodynamic monitoring with assessment of to volemic therapy answer, individualization of target points and maximization of blood flow. Personalized hemodynamic management consisted of applying an adaptive multiparametric approach to hemodynamic assessment. Spontaneous diaphragmatic activity was maintained along all time of mechanical ventilation. The primary endpoint was 28-day mortality rate; secondary endpoints were the duration of cardiovascular dysfunction and the duration of intensive care unit stay. To assess age-dependent data, patients were divided into age subgroups: 1st subgroup - children 1 month - 1 year old; 2nd subgroup - children 1 - 3 years old; 3rd subgroup - children 3 - 6 years old; 4th subgroup - children 6 - 12 years old; 5th subgroup - children 12 - 18 years old. It was determined that the level of 28-day mortality was: in 1st age subgroup - 18.2% in group I and 3.1% in group II (p = 0.02), in the 2nd age subgroup - 11.1% and 0%, respectively (p = 0.11); in the 4th age subgroup - 10% and 0%, respectively (p = 0.28); in the 3rd and 5th age subgroups - was 0% in I and II groups. The prevalence of hemodynamic disorders was: in 1st age subgroup in patients of group I - 100%, while in group II - 62.5% (p = 0.001); in 2nd age subgroup - 55.6% in patients from group I and 42.9% in patients from group II (p = 0.05); in 3rd age subgroup in 100% of patients of group II and only in 75% of patients of group I (p = 0.02). In the 4th age subgroup no significant differences were found between I (30% of patients) and II groups (25% of patients), p = 0.28; in 5th age subgroup the frequency of cardiovascular dysfunction was 40% in group I, compared with 75% in group II (p = 0.008). It was found that duration of hemodynamic insufficiency was longer in patients of 1st and 4th age subgroups, and relatively shorter in patients of 5th age subgroup: in the 1st age subgroup it was 7.6 ± 0.5 days in group I and 8.8 ± 0.9 days in group II (p> 0.05); in 4th age subgroup - 6.7 ± 0.4 days in group I and 10.1 ± 1.2 days in group II (p> 0.05), while in 5th age subgroup - 4.1 ± 0.3 days in group I and 4.7 ± 0.5 days in group II (p> 0.05). We found that there were significant differences in the duration of stay in intensive care unit among patients of the 1st and 5th age subgroups. Specifically, in 1st age subgroup this indicator was in 1.3 times less in group II, compared with group I (p <0.05); in 5th age subgroup the situation was the opposite- the duration of intensive care unit stay in group II was in 1.4 times more in group I (p <0.05). Thus, obtained data demonstrated the results of the use of personalized management of hemodynamic disorders in children with acute respiratory failure. The use of a multiparametric approach to hemodynamic assessment in clinical practice may allow more differentiated use of volume replacement therapy as loop diuretics and will have a beneficial effect on the final clinical outcomes in patients with acute respiratory failure.

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Abstract P147: Office Blood Pressure: An Inadequate Guide to the Diagnosis and Treatment of Hypertension

Hypertension ◽

10.1161/hyp.66.suppl_1.p147 ◽

2015 ◽

Vol 66 (suppl_1) ◽

Author(s):

Jay Cohn ◽

Sue Duval ◽

Natalia Florea ◽

Lynn Hoke ◽

Daniel Duprez

Keyword(s):

Blood Pressure ◽

High Risk ◽

Invasive Disease ◽

Office Blood Pressure ◽

Group Iii ◽

Non Invasive ◽

Group I ◽

Group Ii ◽

Cv Disease ◽

Asymptomatic Individuals

Hypertension is a cardiovascular (CV) disease with high risk for CV morbid events (ME) that benefits from anti-hypertensive therapy. Resting blood pressure (BP) >140/90 mmHg serves as the diagnostic criterion for hypertension, and management has been aimed at BP reduction. Progression of CV disease in the absence of elevated blood pressure identifies individuals who might benefit from CV-protective therapy but are not currently being recognized as in need of treatment. In 2017 asymptomatic individuals evaluated for early functional and structural CV abnormalities, 1534 not taking anti-hypertensive drugs were available to determine the relationship between office blood pressure and the severity of CV abnormalities, as defined by a 10-test non-invasive disease score (DS) of 0-20. Previous studies have documented the high predictive value of DS for future CVME. The population was 53% male, average age 50±11 years, BP 122/77mmHg, LDL cholesterol 129±38 mg/dL, HDL 52±17mg/dL, triglycerides 109 mg/dL. DS was adjusted by eliminating the score for BP, but 9-test DS was still directly related to BP: 2.3 in those (n=550) <120/80 mmHg (Group I), 3.2 in those 120-129/80-85 mmHg (n=600) (Group II), 4.1 in those 130-139/85-89 mmHg (n=236) (Group III), and 5.7 in those 140+/90+mmHg (n=148) (Group IV). Nonetheless, DS of >6 indicative of high risk was present in 10% of Group I, 20% of Group II and 30% of Group III. BP was largely overlapping in individuals with no CV disease (DS 0-2), early disease (DS 3-5) and advanced disease (DS 6+). Therefore, reliance on resting BP leaves many at-risk individuals undiagnosed and untreated for early CV disease likely to progress. The hypertensive state exists in the absence of elevated BP and should be recognized and treated to prevent CVME.

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Local Cerebral Blood Flow and the Electrocorticogram during Sodium Nitroprusside Hypotension

Anaesthesia and Intensive Care ◽

10.1177/0310057x7800600402 ◽

1978 ◽

Vol 6 (4) ◽

pp. 290-296 ◽

Cited By ~ 5

Author(s):

C. L. Miller ◽

D. G. Lampard ◽

R. I. Griffiths ◽

W. A. Brown

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Cardiac Output ◽

Cerebral Blood Flow ◽

Intracranial Pressure ◽

Sodium Nitroprusside ◽

Large Range ◽

Local Cerebral Blood Flow ◽

Hydrogen Electrode ◽

Electrode Technique

Changes in local cerebral blood flow during sodium nitroprusside hypotension were measured using the hydrogen electrode technique. At mean arterial pressures from 90% to 50% of control values, local cerebral blood flow showed a significant decrease by 20%. When blood pressure was reduced below 50%, the local cerebral blood flow increased significantly and approached control levels. It is suggested that the flow increase may be due to local hypoxia. Associated with this increase were electrocorticogram changes indicative of hypoxia. The significant decrease in mean local cerebral blood flow and the large range of flows seen during mild hypotension indicate that autoregulation is impaired. During hypotension, intracranial pressure increased by, at most, 3 mm Hg. Cardiac output was usually unaffected and was never decreased by more than 20%.

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Central hemodynamic and splanchnic circulation in children with meningococcal septic shock

Regulatory Mechanisms in Biosystems ◽

10.15421/021716 ◽

2017 ◽

Vol 8 (1) ◽

pp. 91-97

Author(s):

M. A. Georgiyants ◽

V. A. Korsunov ◽

O. M. Olkhovska

Keyword(s):

Blood Pressure ◽

Septic Shock ◽

Blood Flow ◽

Cardiac Output ◽

Ejection Fraction ◽

Stroke Volume ◽

Blood Flow Rate ◽

Healthy Children ◽

Group I ◽

Meningococcal Septic Shock

Meningococcal infection is caused by the bacterium Neisseria meningitidis (also termed meningococcus). Invasive meningococcal disease remains a rare infectious disease not only with high mortality but also with important morbidity and remains as a leading cause of sepsis and septic shock. The pathogenic mechanisms of microcirculatory disorders in meningococcal septic shock have been subject to controversy. This article presents the results of a study of 11 paediatric patients’ (4 boys and 7 girls) with meningococcal septic shock (Group I) who were hospitalized at the Regional Children's Infectious Hospital from 2009 to 2011. The average age of the patients was 37.4 ± 8.4 mo. Septic shock was diagnosed according to International Pediatric Sepsis Consensus Conference: definitions of criteria for sepsis and organ dysfunction in paediatrics. Heart rate, respiratory rate, systolic blood pressure, diastolic blood pressure, average blood pressure, SpO2 were monitored. The cardiac output, ejection fraction, fraction shortening, stroke volume were measured by ultrasound in M-mode by Teichholz method. Blood circulation in the a. mesenterica, a. hepatica, a. lienalis, a. renal sinister, v. porta, v. lienalis, v. renal sinister was determined by impulse Doppler’s wave. Acid-base and electrolytes level in serum, nitric oxide (NO), endothelin I, creatinine, C-reactivity protein and lactate blood level were measured. The control group consisted of 21 healthy children (9 boys and 12 girls), aged 37.5 ± 5.4 mo. in average (Group II). We used t-criteria (Student’s) and correlation with R-criteria (Spearmen) for statistical analysis. The data showed a statistically significant lower fraction of ejection, fraction of shortening, stroke volume in Group I. Moreover, our data showed a statistically high level of mesenterial and portal blood flow rate and high pulse index in v. renal sinister compared to healthy children. The blood level of NO was increased in Group I as well as in Group II. Direct correlations were determined between the level of NO and mesenteric, hepatic arterial and venous blood flow rate. Statistically significant inverse correlations between the level of NO and pulse resistive index in splanchnic vessels were discovered as well as inverse correlations between the NO level and the indicator of the severity of condition on PRISM scale (r = –0.952). At the same time, we have found no correlation between splanchnic circulation value and cardiac output. Based on the results of this study, we consider that NO has organ protective effects in children with meningococcal sepsis. Future research should aim to introduce new strategies of intensive care for patients with meningococcal septic shock with early use of inotrope and NO-donor therapy in fluid restriction combination.

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Treatment and Prevention of Diaphragm Fatigue Using Low-Dose Dopamine

Biological Research For Nursing ◽

10.1177/1099800402003003004 ◽

2002 ◽

Vol 3 (3) ◽

pp. 140-149 ◽

Cited By ~ 9

Author(s):

Janet D. Pierce ◽

Richard L. Clancy ◽

Nan Smith-Blair ◽

Robert Kraft

Keyword(s):

Blood Flow ◽

Intensive Care ◽

Intensive Care Units ◽

Low Dose ◽

Aortic Blood Flow ◽

Group Iii ◽

Aortic Blood ◽

Group I ◽

Group Ii ◽

Diaphragm Fatigue

There is increasing evidence that diaphragm fatigue is a major cause of failure in weaning patients frommechanical ventilation. Patients in intensive care units are often administered dopamine to improve renal blood flow without regard to its effect on diaphragmblood flow. The aimof this study was to investigate if intravenous low-dose dopamine, equivalent to the dose used in intensive care units, can treat and prevent diaphragmfatigue. Diaphragmfatigue was produced in anesthetized rats by inspiratory resistance loading (IRL). The effect on diaphragmshortening, diaphragmblood flow, and aortic blood flow was determined. When diaphragm fatigue was attained, group I was given saline for 30 min while maintaining IRL. At the time of diaphragm fatigue, group II was given low-dose dopamine (2 μg/kg/min) for 30 min while maintaining IRL. In group III, dopamine administration was started before and continued throughout the period of IRL. Administering dopamine after the development of diaphragm fatigue (group II) increased diaphragm performance as measured by increased diaphragmshortening and was accompanied by an increased diaphragmblood flow. Administering dopamine prior to and throughout IRL (group III) prevented diaphragmfatigue. Low-dose dopamine can prevent and/or reverse diaphragmfatigue in rats without a significant change in aortic blood flow. This effect of dopamine may be due to increased oxygen delivery associated with the increased diaphragm blood flow, resulting in less free radical formation and thus less muscle damage.

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Cerebral blood flow autoregulation in early experimental S. pneumoniae meningitis

Journal of Applied Physiology ◽

10.1152/japplphysiol.00697.2006 ◽

2007 ◽

Vol 102 (1) ◽

pp. 72-78 ◽

Cited By ~ 11

Author(s):

Michael Pedersen ◽

Christian T. Brandt ◽

Gitte M. Knudsen ◽

Christian Østergaard ◽

Peter Skinhøj ◽

...

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Cerebral Blood Flow ◽

Intracranial Pressure ◽

Cerebral Perfusion ◽

Perfusion Pressure ◽

Arterial Blood ◽

Norepinephrine Infusion ◽

Intracisternal Injection ◽

Cerebral Blood Flow Autoregulation

We studied cerebral blood flow (CBF) autoregulation and intracranial pressure (ICP) during normo- and hyperventilation in a rat model of Streptococcus pneumoniae meningitis. Meningitis was induced by intracisternal injection of S. pneumoniae. Mean arterial blood pressure (MAP), ICP, cerebral perfusion pressure (CPP, defined as MAP − ICP), and laser-Doppler CBF were measured in anesthetized infected rats ( n = 30) and saline-inoculated controls ( n = 30). CPP was either incrementally reduced by controlled hemorrhage or increased by intravenous norepinephrine infusion. Twelve hours postinoculation, rats were studied solely during normocapnia, whereas rats studied after 24 h were exposed to either normocapnia or to acute hypocapnia. In infected rats compared with control rats, ICP was unchanged at 12 h but increased at 24 h postinoculation (not significant and P < 0.01, respectively); hypocapnia did not lower ICP compared with normocapnia. Twelve hours postinoculation, CBF autoregulation was lost in all infected rats but preserved in all control rats ( P < 0.01). Twenty-four hours after inoculation, 10% of infected rats had preserved CBF autoregulation during normocapnia compared with 80% of control rats ( P < 0.01). In contrast, 60% of the infected rats and 100% of the control rats showed an intact CBF autoregulation during hypocapnia ( P < 0.05 for the comparison of infected rats at normocapnia vs. hypocapnia). In conclusion, CBF autoregulation is lost both at 12 and at 24 h after intracisternal inoculation of S. pneumoniae in rats. Impairment of CBF autoregulation precedes the increase in ICP, and acute hypocapnia may restore autoregulation without changing the ICP.

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