Mean CPP Research Articles

Acoustic Characteristics and Voice Fatigue in Hearing Impared Adult Males according to the Degree of Hearing Loss

This study was conducted to use it as basic information to suggest the necessity and program for self-regulation that can properly maintain voice according to the degree of hearing loss. For this purpose, twenty-six men in their fifties were classified according to the degree of hearing loss, and multidimensional voice program (MDVP) (F<sub>0</sub>, jitter, shimmer, noise to harmonics ratio [NHR]), cepstrum (cepstral peak prominence [CPP], low/high spectral ratio [L/H ratio], mean CPP F<sub>0</sub>, cepstral/spectral index of dysphonia [CSID]) and vocal fatigue index (fatigue, physical, rest, total) were performed and analyzed. The more severe the degree of hearing loss, the higher the F<sub>0</sub> and CSID, and the lower the L/H ratio, the overall quality of the voice deteriorated. Normal-mild hearing loss group indicated a positive correlation between mean CPP F<sub>0</sub> and fatigue, rest and total, and negative correlation between CPP and rest. In severe-profound group, F<sub>0</sub> and rest showed a negative correlation, and shimmer and rest showed a positive correlation. Through the analysis of vowel and connected speech, it was found that the more severe the degree of hearing loss, the higher the F<sub>0</sub> in vowel phonation, the lower the L/H ratio and the higher the CSID, and the lower the overall sound quality. In addition, it was observed that that the more severe the hearing loss, the higher the fatigue level of the hearing-loss person who speaks due to severe voice misuse and abuse. Therefore, auditory rehabilitation patients with hearing loss optimal voice production, and voice rehabilitation programs that use proper voices should be supported.

Determinants of arterial stiffness in patients with type 2 diabetes mellitus: a cross sectional analysis

In patients with type 2 diabetes mellitus (T2DM) arterial stiffness is associated with increased cardiovascular and total mortality. Little is known about determinants of arterial stiffness in clinical routine. Identification of potential determinants of arterial stiffness will help to address treatment targets for patients in the early state of T2DM. This is a cross-sectional analysis of arterial stiffness in 266 patients in the early stage of T2DM who did not have cardiovascular or renal complications. Parameters of arterial stiffness such as central systolic blood pressure (cSBP), central pulse pressure (cPP) and pulse wave velocity (PWV) were measured with the SphygmoCor System (AtCor Medical). We investigated the influence of parameters of glucose metabolism, lipid status, body constitution, blood pressure (BP) and inflammation on the stiffness parameters using multivariate regression analysis. The study cohort consisted of male and female patients aged 61 ± 8 years with mean diabetes duration of 6.4 ± 5.1 years, mean HbA1c 7.1 ± 0.9%, mean cSBP 121 ± 12 mmHg, mean cPP 44 ± 10 mmHg and mean PWV 8.9 ± 1.8 m/s. Multiple regression analysis identified waist circumference (WC) (beta = 0.411, p = 0.026), LDL-cholesterol (beta = 0.106, p = 0.006), systolic office BP (beta = 0.936, p < 0.001) and diabetes duration (beta = 0.233, p = 0.043) as potential determinants of cSBP. cPP was determined by sex (beta = 0.330, p = 0.008), age (beta = 0.383, p < 0.001), systolic office BP (beta = 0.370, p < 0.001) and diabetes duration (beta = 0.231, p = 0.028) whereas for PWV the following determinants could be identified: age (beta = 0.405, p < 0.001), systolic office BP (beta = 0.421, p < 0.001) and diabetes duration (beta = 0.073, p = 0.038). In addition to the known parameters age, sex and systolic office BP serum LDL-cholesterol, WC and diabetes duration have been identified as determinants of arterial stiffness in patients with T2DM. Treatment of patients in the early stage of T2DM should focus on these clinical parameters to prevent progression of arterial stiffness and as a consequence reduce cardiovascular mortality.Trial registration: The patients included in the analysis participated in one of the following clinical trials NCT02752113 (registered 26.4.2016), NCT02383238 (09.03.2015), NCT02471963 (15.06.2015), NCT01319357 (21.03.2011) (http://www.clinicaltrials.gov).

Evaluating the Arterial Stiffness as a Useful Tool in the Management of Obese Children

Childhood obesity speeds up the development of arterial stiffness and progressively increases the values of arterial pressure. The purpose of this study is to investigate the value of using pulse wave analysis (PWA) to measure arterial stiffness as a sign of vascular wall impairment in obese children. The research was focused on 60 subjects: 33 obese and 27 normal-weight. Ages ranged from 6 to 18 years old. PWA includes parameters such as pulse wave velocity (PWV), augmentation index (AIx), peripheral and central blood pressure (SBP, DBP, cSBP, cDBP), heart rate, and central pulse pressure (cPP). The device used was a Mobil-O-Graph. Blood parameters were taken from the subject's medical history, not older than 6 months. A high BMI and a large waist circumference are linked to a high PWV. The levels of LDL-c, triglycerides (TG), non-HDL-c, TG/HDL-c ratio, and total cholesterol-HDL-c ratio significantly correlate to PWV, SBP, and cSBP. Alanine aminotransferase is a reliable predictor of PWV, AIx, SBP, DBP, and cDBP, while aspartate aminotransferase is a significant predictor of AIx, mean arterial pressure (MAP), cSBP, and cPP. 25-OH-Vitamin D negatively correlates with PWV, SBP, and MAP and significantly predicts the MAP. Cortisol and TSH levels are not significant to arterial stiffness in obese children without specific comorbidities and neither is fasting glucose in obese children without impaired glucose tolerance. We conclude that PWA contributes valuable data regarding patients' vascular health and should be considered a reliable tool in the management of obese children.

Monitoring the particulate phosphorus concentration of inland waters on the Yangtze Plain and understanding its relationship with driving factors based on OLCI data

Tracking the spatiotemporal dynamics of particulate phosphorus concentration (CPP) and understanding its regulating factors is essential to improve our understanding of its impact on inland water eutrophication. However, few studies have assessed this in eutrophic inland lakes, owing to a lack of suitable bio-optical algorithms allowing the use of remote sensing data. Herein, a novel semi-analytical algorithm of CPP was developed to estimate CPP in lakes on the Yangtze Plain, China. The independent validations of the proposed algorithm showed a satisfying performance with the mean absolute percentage error and root mean square error less than 27% and 27 μg/L, respectively. The Ocean and Land Color Instrument observations revealed a remarkable spatiotemporal heterogeneity of CPP in 23 lakes on the Yangtze Plain from 2016 to 2020, with the lowest value in December (62.91 ± 34.59 μg/L) and the highest CPP in August (114.9 ± 51.69 μg/L). Among the 23 examined lakes, the highest mean CPP was found in Lake Poyang (124.58 ± 44.71 μg/L), while the lowest value was found in Lake Qiandao (33.51 ± 4.71 μg/L). Additionally, 13 lakes demonstrated significant decreasing or increasing trends (P < 0.05) of annual mean CPP during the observation period. The driving factor analysis revealed that four natural factors (wind speed, air temperature, precipitation, and sunshine duration) and two anthropogenic factors (the normalized difference vegetation index and nighttime light) combined explained more than 91% of the variation in CPP, while the impacts of these factors on CPP showed considerable differences among lakes. This study offered a novel and scalable algorithm for the study of the spatiotemporal variation of CPP in inland waters and provided new insights into the regulating factors in water eutrophication.

Characterization of Primary Muscle Tension Dysphonia Using Acoustic and Aerodynamic Voice Metrics

Objectives/HypothesisThe objectives of this study were to (1) identify optimal clusters of 15 standard acoustic and aerodynamic voice metrics recommended by the American Speech-Language-Hearing Association (ASHA) to improve characterization of patients with primary muscle tension dysphonia (pMTD) and (2) identify combinations of these 15 metrics that could differentiate pMTD from other types of voice disorders. Study DesignRetrospective multiparametric MethodsRandom forest modeling, independent t-tests, logistic regression, and affinity propagation clustering were implemented on a retrospective dataset of 15 acoustic and aerodynamic metrics. ResultsTen percent of patients seen at the New York University (NYU) Voice Center over two years met the study criteria for pMTD (92 out of 983 patients), with 65 patients with pMTD and 701 of non-pMTD patients with complete data across all 15 acoustic and aerodynamic voice metrics. PCA plots and affinity propagation clustering demonstrated substantial overlap between the two groups on these parameters. The highest ranked parameters by level of importance with random forest models—(1) mean airflow during voicing (L/sec), (2) mean SPL during voicing (dB), (3) mean peak air pressure (cmH2O), (4) highest F0 (Hz), and (5) CPP mean vowel (dB)—accounted for only 65% of variance. T-tests showed three of these parameters—(1) CPP mean vowel (dB), (2) highest F0 (Hz), and (3) mean peak air pressure (cmH2O)—were statistically significant; however, the log2-fold change for each parameter was minimal. ConclusionComputational models and multivariate statistical testing on 15 acoustic and aerodynamic voice metrics were unable to adequately characterize pMTD and determine differences between the two groups (pMTD and non-pMTD). Further validation of these metrics is needed with voice elicitation tasks that target physiological challenges to the vocal system from baseline vocal acoustic and aerodynamic ouput. Future work should also place greater focus on validating metrics of physiological correlates (eg, neuromuscular processes, laryngeal-respiratory kinematics) across the vocal subsystems over traditional vocal output measures (eg, acoustics, aerodynamics) for patients with pMTD. Level of EvidenceII

Albuminuria Intensifies the Link Between Urinary Sodium Excretion and Central Pulse Pressure in the General Population: The Wakuya Study.

BACKGROUNDCentral pulse pressure (cPP) is responsible for the hemodynamics of vital organs, and monitoring this parameter is important for cardiovascular disease (CVD) prevention. Excess sodium intake and (micro)albuminuria (a manifestation of renal microvascular damage) are known to be strong predictors of CVD. We sought to investigate the cross-sectional relationships among dietary sodium intake, albuminuria, and cPP in a general population cohort.METHODSThe subjects were 933 apparently healthy adults (mean age, 56 ± 10 years). Radial pressure waveforms were recorded with applanation tonometry to estimate mean arterial pressure (MAP), cPP, forward and backward pressure amplitudes, and augmentation index. The urinary sodium/creatinine and albumin/creatinine ratios were measured in spot urine samples.RESULTSBoth the urinary sodium/creatinine and albumin/creatinine ratios were positively correlated with cPP, even after adjusting for MAP (P < 0.001). Moreover, both ratios had a synergistic influence on increasing the cPP independent of age, sex, estimated glomerular filtration rate, hyperlipidemia, and diabetes (interaction P = 0.04). A similar synergistic influence was found on the forward pressure amplitude, but not on the backward pressure amplitude or augmentation index. The overall results were not altered when the urinary albumin/creatinine ratio was replaced with the existence of chronic kidney disease (CKD).CONCLUSIONS(Micro)albuminuria strengthens the positive association between urinary sodium excretion and cPP and systolic forward pressure. Excess sodium intake may magnify the cardiovascular risk by widening the aortic pulsatile pressure, particularly in the presence of concomitant CKD.

Impact of International Coauthorships to A Young Malaysian University Specializing in Science, Technology, Engineering and Mathematics (STEM)

Internationalization is defined as a process of integrating an international, intercultural, or global dimension into the teaching and learning of education. International co-authorship in research article is one of the means of collaboration towards internationalization. This paper investigates the impact of international co-authorship in the field of Science, Technology, Engineering and Mathematics (STEM) for a specialised young university (&lt;50 years old). The study focused on approximately 9450 articles and the citations ranging from 2012-2017. The impact due to annual article publication, annual citation count, most cited article, annual citation per article and the correlation between the publication and citation were analysed. The finding shows that faculty members of the university have been collaborated with authors from 86 countries since 1997, which dominated by Asian institutions. Amongst, top 30 countries with highest international co-authored publications were identified, which led by Pakistan, Saudi Arabia, India, United Kingdom and Japan. Further in detail, annual citation per article (Cpp) showed that collaborations with European countries e.g. Spain, Netherlands, and Hungry, resulting greater mean Cpp. On the other hand, the analysis on the cumulative citation trend illustrated that the citation count is proportional to the number of articles. This study evinced that international co-authorship does show positive impacts to a STEM specialised young university.

Abstract 257: Unselective Pulmonary Vasodilation is an Important Factor in Sodium Nitroprusside Enhanced Cardiopulmonary Resuscitation Improved Blood Flow

Introduction: Sodium nitroprusside enhanced CPR (SNPeCPR) is a novel CPR method that includes a potent vasodilator, active compression-decompression CPR, an inspiratory impedance threshold device and abdominal binding. SNPeCPR has been shown to improve vital organ flow and functional survival outcomes compared to standard CPR methods in animals. We hypothesize that one of the main effects of SNPeCPR mediated increase in cardiac output during prolonged resuscitation is profound pulmonary artery vasodilation. Methods: After electrically induced VF was left untreated for 3 min, 20 (44-48Kg) pigs were randomized to receive SNPeCPR (10) or standard CPR (10) for a total of 30 min; the first 10 minutes were BLS CPR followed by twenty minutes of ACLS. During ACLS, animals were given IV SNP (1mg bolus) or standard epinephrine (0.5mg) q5 min until ROSC or 45 min total CPR. Shocks were delivered after 30 minutes of CPR at 300J. If ROSC was achieved, animal was monitored until 4-hour endpoint. Ventilations were provided with 10ml/kg at 10/min with a mechanical ventilator. Initially during CPR, room air was used and FiO2 was adjusted q5 minutes to maintain O 2 %saturation &amp;gt 92% based on ABG. Lactic acid was also measured. Aortic, right atrial, and coronary artery pressures and carotid blood flow were recorded continuously. A-a oxygen gradient was measured with standard technique. Results: SNPeCPR animals documented a significantly higher mean CPP, lower lactic acid and 3x higher carotid blood flow over 30 minutes compared to standard CPR as previously documented. A-a oxygen gradient was dramatically increased in the SNPeCPR and coincided with a decreased lactate level (see Figure 1). Discussion: SNPeCPR causes profound pulmonary vasodilation and increases flow through non-ventilated lung areas. Despite that, the overall increase in forward flow leads to higher minute O 2 delivery and improved tissue perfusion. SNPeCPR should be used with 100% oxygen in the first human clinical trial.

내전형연축성 발성장애 음성에 대한 켑스트럼과 스펙트럼 분석

The purpose of this study was to analyze perceptual and spectral/cepstral measurements in patients with adductor spasmodic dysphonia(ADSD). Sixty participants with gender and age matched individuals(30 ADSD and 30 controls) were recorded in reading a sentence and sustained the vowel /a/. Acoustic data were analyzed acoustically by measuring CPP, L/H ratio, mean CPP F0 and CSID, and auditory-perceptual ratings were measured using GRBAS. The main results can be summarized as below: (a) the CSID for the connected speech was significantly higher than for the sustained vowel (b) the G, R and S for the connected speech were significantly higher than for the sustained vowel (c) Spectral/cepstral parameters were significantly correlated with the perceptual parameters, and (d) the ROC analysis showed that the threshold of 13.491 for the CSID achieved a good classification for ADSD, with 86.7% sensitivity and 96.7% specificity. Spectral and cepstral analysis for the connected speech is especially meaningful on cases where perceptual analysis and clinical evaluation alone are insufficient.

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Background and aims: Multi-modal monitoring (MMM) has been used to manage traumatic brain injury (TBI) in adults1; however, there is limited experience in paediatrics2. MMM is used to derive real time optimum cerebral perfusion pressure (CPPopt) at which the cerebral autoregulation is the best by monitoring cerebrovascular reactivity defined by pressure reactivity index (PRx) [derived from slow wave variations in arterial blood pressure (ABP) and intracranial pressure (ICP)]. Aims: We present our experience of using MMM in Paediatric intensive care unit (PICU). Methods: In a group of 7 severe TBI and 1 encephalitis patients, MMM was conducted including ICP, ABP, CPP, heart rate (HR), ventilator parameters, pulse oximetry (SPaO2) supported by dedicated software (ICM+; www.neurosurg.cam.ac.uk/icmplus). We additionally evaluated PRx and CPPopt. Results: 1. In non-survivors, ICP was significantly higher (37 + 30 mm Hg versus 13.1+ 2.9 mm Hg; p<0.05). 2. Non-survivors had prolonged periods of deteriorating PRx (PRx >0.3, coded with colour line, so called solid-red line). Overall mean PRx in these patients was worse (survivors PRx=0.06; non-survivors=0.32; p=0.18). 3. Non-survivors had a tendency to lower mean CPP than CPPopt (CPP-CPPopt: 1.5 mm Hg vs -14 mm Hg; p=0.10). 4. CPPopt varied from 60 to 80 mm Hg in this group of patients. This indicates that fixed therapeutic threshold for CPP may not be applicable to all TBI patients treated with age appropriate CPP. Conclusions: Additional data needs to be collected before any further conclusions can be drawn.

Community collaboration improves blood pressure control by 13.5% in a medium-sized metropolitan area

The purpose of this study was to compare CPP (a surrogate for aortic elasticity) in a population of 59 obese pts whose BMI was >30kg/sqm. These pts were divided into hypertensive obese (HTNO) 35 pts and normotensive obese (NTO) 24 pts. Both groups were also divided according to age to the following groups: 30-39, 40-49, 50-59, and over 60 years of age. We also compared both groups, to a group of 100 volunteers (Control group, CTRL) that were normotensive and nonobese. CPP was determined using the Sphygmocor System. The mean CPP for HTNO pts was 48.8 15 mmHg. Mean CPP for NTO pts was 45.5 13 mmHg. Mean CPP for CTRL pts was 44.0 7.7 mmHg. The mean CPP difference between HTNO pts and CTRL pts was significant with a p 1⁄4 0.03; the mean CPP difference between NTO pts and CTRL pts was nonsignificant with a p 1⁄4 0.198. These results are shown graphically in figure #1. We conclude that even in a small population of HTNO and NTO pts, CPP was able to show a significant difference between HTNO compared to CTRL. This finding may suggest that hypertensive obese pts may have a higher vascular risk than NTO because of impaired aortic elasticity. Our preliminary finding should be confirmed by studying a larger population of obese pts and including pulse wave velocity.

The Role of Microclot Formation in an Acute Subarachnoid Hemorrhage Model in the Rabbit

Background. Microvascular dysfunction and microthrombi formation are believed to contribute to development of early brain injury (EBI) after aneurysmal subarachnoid hemorrhage (SAH). Objective. This study aimed to determine (i) extent of microthrombus formation and neuronal apoptosis in the brain parenchyma using a blood shunt SAH model in rabbits; (ii) correlation of structural changes in microvessels with EBI characteristics. Methods. Acute SAH was induced using a rabbit shunt cisterna magna model. Extent of microthrombosis was detected 24 h post-SAH (n = 8) by fibrinogen immunostaining, compared to controls (n = 4). We assessed apoptosis by terminal deoxynucleotidyl transferase nick end labeling (TUNEL) in cortex and hippocampus. Results. Our results showed significantly more TUNEL-positive cells (SAH: 115 ± 13; controls: 58 ± 10; P = 0.016) and fibrinogen-positive microthromboemboli (SAH: 9 ± 2; controls: 2 ± 1; P = 0.03) in the hippocampus after aneurysmal SAH. Conclusions. We found clear evidence of early microclot formation in a rabbit model of acute SAH. The extent of microthrombosis did not correlate with early apoptosis or CPP depletion after SAH; however, the total number of TUNEL positive cells in the cortex and the hippocampus significantly correlated with mean CPP reduction during the phase of maximum depletion after SAH induction. Both microthrombosis and neuronal apoptosis may contribute to EBI and subsequent DCI.

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Introduction: Hypertonic saline (HTS) remains a cornerstone of therapy in current treatment guidelines for traumatic brain injury (TBI), intracranial hemorrhage (ICH), ischemic stroke (IS), and subarachnoid hemorrhage (SAH) in order to provide optimal management of intracranial pressure (ICP) following initial brain injury. HTS is available in several concentrations and is often used as a continuous or intermittent infusion; however there is limited data on the intermittent use of 23.4% HTS in severe brain injury. Methods: Critically-ill patients receiving 23.4% HTS following brain injury between 2012 and 2013 were included in this single-center, retrospective study. Data collected include patient demographics, concomitant use of HTS continuous infusions, mean arterial pressure (MAP), and ICP values during use of 23.4% HTS therapy. The primary endpoint used to determine efficacy was mean change in ICP following administration of intermittent HTS. Secondary endpoints used to determine safety include post-infusion electrolyte abnormalities, hemodynamic data, and physician ordering characteristics. Demographic data, primary, and secondary endpoints were analyzed using descriptive statistics. Results: Twenty-one patients were evaluated with demographics as follows: average age 39 years, mean admission GCS 6.2, and mean ICP 15.4 mmHg. Indications for HTS therapy include TBI (52.4%), ICH (9.5%), SAH (23.8%), IS (9.5%) and intraventricular hemorrhage (4.8%). Mean length of HTS therapy was 3.1 days with an average of 5.4 doses administered per patient. Mean ICP before and after 23.4% HTS boluses were 25.4 mmHg and 18.2 mmHg, respectively. A total of 114 HTS boluses resulted in 104 reductions in ICP. Mean percentage decrease in ICP after administration of 23.4% HTS was 29.7. ICP values decreased by an average of 7.1 mmHg following doses of 23.4% HTS. Average serum sodium and serum osmolality concentrations following HTS administration increased by 1.3 mEq/L and 4.4 mOsm/kg, respectively. Mean MAP and CPP during HTS therapy were 95.8 mmHg and 76.2 mmHg, respectively. Conclusions: Significant reductions in ICP were seen following administration of 23.4% HTS boluses. Significant increases in serum sodium and serum osmolality, as well as changes in hemodynamics after HTS boluses were not observed. Overall, intermittent doses of 23.4% HTS appear to be a safe and effective treatment for the management of increased ICP following severe brain injury.

Feasibility of a Continuous Computerized Monitoring of Cerebral Autoregulation in Neurointensive Care

In order to monitor cerebral autoregulation status, a software package was developed to calculate a cerebral autoregulation index (pressure reactivity index, PRx). The aim of this study is to evaluate whether the application of this methodology is feasible and useful in the clinical setting. Prospective observational study. NeuroIntensive Care Unit (NICU) of a university-affiliated teaching hospital. Twenty-six consecutive patients admitted to NICU requiring intracranial pressure (ICP) and invasive arterial pressure (AP) monitoring. Patient's data were collected for a total of 902 h. Mean PRx was calculated utilizing 2 h time window. CPP-PRx distribution graphs were calculated from CPP of 20 to 110 mmHg using 10 mmHg intervals. Autoregulation was preserved in 18% observations (83/451) and deranged in 49% observations (220/451). In 33% observations (148/451), autoregulation could not be clearly defined (0 < PRx < 0.2). Even if no clinical protocol was developed, autoregulation status information inserted in clinical decision pathway influenced clinical management. Mean CPP, calculated at maximum and minimum ICP every 2 h interval, resulted different between groups with good and poor reactivity (67 +/- 17.6 and 85 +/- 20.0 mmHg, respectively, for autoregulating observations and 60 +/- 19.1 and 67 +/- 19.4 mmHg, respectively, for nonautoregulating observations, P < 0.001, independent samples t-test). PRx values were normally distributed. Our study demonstrates that a daily bedside measure of cerebral autoregulation is feasible. PRx values can support clinicians in the identification of a targeted CPP in patients suffering from different intracranial pathologies and requiring an intensive monitoring.

Multicenter evaluation of propofol for head-injured patients in Taiwan

Background The present study was a multicenter, retrospective study which aimed to evaluate the efficacy of propofol, a new choice of pharmacotherapy in head-injured patients. Methods Head-injured patients admitted to 3 hospitals during the period from January 2003 to December 2004 were included in this clinical trial. Data on patients' demographics, laboratory data, GCS score, ICP, CPP, concurrent medications, and therapeutic outcomes were collected. Results Among the 104 patients included, only 44 were given propofol. The average age was 40.8 ± 22 years for all patients, with 41.91 ± 20.41 and 43.48 ± 23.19 years for the propofol group and nonpropofol group, respectively ( P = .097). There was no significant difference in baseline GCS score between the 2 groups (5.86 ± 1.84 vs 5.66 ± 1.59, P = .729). Mean ICP for the first 3 days in the ICU was 17.23 ± 9.0 mm Hg in the propofol group and 33.19 ± 32.56 in the nonpropofol group, respectively ( P = .017). Mean CPP for the first 5 days in the ICU was 71.10 ± 15.32 mm Hg in the propofol group and 43.20 ± 29.92 mm Hg in the nonpropofol group ( P < .001). A higher survival rate was found in the propofol group (81.8% vs 46.7%, P < .001). Conclusions The present study demonstrated that propofol improved the outcome in recovery phase of head-injured patients.

Multiparametric analysis of cerebral substrates and nitric oxide delivery in cerebrospinal fluid in patients with intracerebral haemorrhage: correlation with hemodynamics and outcome

There is no information regarding the possible role of cerebral substrates in the pathogenesis of neuronal injury in intracerebral haemorrhages (ICHs). Purposes of this prospective study were to clarify whether changes in substrates are the consequence of the initial brain damage in ICH and to elucidate the relationship among the biochemical mechanisms and clinical course of patients with ICH. During a period of two years, patients (GCS < or =8) who had ICH secondary to an aneurysm (SAH), stroke (sICH), or trauma (tICH) and underwent ventriculostomy with ICP monitoring and/or underwent cranial surgery were randomly enrolled in this study. Extracellular concentrations of glutamate, aspartate, glycine, GABA, lactate, lactate/pyruvate ratio, and glucose in the CSF were measured by use of high-performance liquid chromatography (HPLC). The nitric oxide (NO) concentration in the CSF was analyzed by chemiluminescence. There were 75 patients (38 women and 37 men) with ICH included in this study. Twenty-one patients had SAH, 28 sICH, and 26 tICH. In tICH patients, there was a 30-fold increase in glutamate and a 10-fold in aspartate over reference values. The levels of glutamate, aspirate, GABA, lactate, glucose, and NO differed significantly among the three groups (p<0.001). There were no significant differences in glycine and L/P ratio among the groups. The initial GCS, the mean CPP and outcome six months after the insult were all significantly correlated with the concentration of substrates (p<0.01), both within groups and among the total sample. The CSF levels of glutamate lactate, NO and glucose correlated significantly with outcome (p<0.005). This study confirms the correlation between the level of EAAs and the outcome of ICHs, suggesting that neurochemical monitoring of these substances may have a role in caring for patients.

Safety and efficacy of dexmedetomidine in neurosurgical patients

Primary objective: Very little information regarding effects on ICP, CPP and the safety of dexmedetomidine in neurosurgical patients has been published. The objective of this study is to gather information on the dosage, sedative effects and adverse effects of dexmedetomidine in neurosurgical patients.Research design: The study design was retrospective and descriptive.Methods and procedures: Computerized data were collected from the records of 39 neurosurgical patients in the ICU who received dexmedetomidine between October 2001 and December 2004. MAP, SBP, DBP, HR, ICP and CPP were recorded. The parameter means and standard deviations were obtained and plotted against time.Experimental interventions: Dexmedetomidine, an alpha-2 agonist, provides adequate sedation without altering respiratory drive, while facilitating frequent neurological examinations. The FDA approved a dosage range for a loading infusion of 0.1 mcg kg−1infused over 10 minutes followed by 0.2–0.7 mcg kg−1 h−1continuous infusion for 24 hours.Main outcomes and results: A total of 39 patients were enrolled in the study; 26 men and 13 women. The mean age was 34 years. Of the patients enrolled in the study, 15 were successfully extubated with no adverse reactions while maintaining adequate sedation. Agitation was the predominant adverse reaction. Hypotension occurred in 10 patients. The mean CPP increased and the mean ICP decreased. The standard deviation for the means of the ICP and CPP were small and did not fluctuate as widely as the haemodynamic parameters.Conclusions: Dexmedetomidine can be a safe and effective sedative agent for neurosurgical patients. A loading infusion should be avoided and higher maintenance doses may be required to ensure adequate sedation. Further studies are necessary to establish an optimal dosage regimen.

Can cerebral autoregulation be assessed without measuring cerebral blood flow?

Cerebral autoregulation is becoming more popular as a useful parameter in clinical practice. It has been demonstrated that dynamic autoregulation assessed using transcranial Doppler ultrasongraphy is associated with outcome following severe head injury, worsens with impairment of cerebral blood inflow in patients with carotid artery stenotic disease and when vasospasm arises in patients after subarachnoid haemorrhage, etc 1. Although current techniques for calculation of dynamic autoregulation do not require pharmacological changes in arterial pressure, the measurement in clinical practice is still difficult and depends on continuous insonation of the Middle Cerebral Artery- subject to artifacts mainly caused by the minor displacement of the ultrasound probes. We introduced Pressure Reactivity Index (PRx) derived from continuous monitoring of arterial pressure (AP) and intracranial pressure (ICP) to clinical practice in 1990 s. Previously PRx has been positively correlated with outcome 1, PET-CBF derived autoregulation 2 and cerebral metabolism rate for oxygen 3. Our objective was to correlate PRx with Transcranial Doppler dynamic autoregulation index (Mx) and and outcome in a large group of head injured patients. Data from intermittent bedside monitoring of ICP, AP, cerebral perfusion pressure (CPP=ABP-ICP) and of transcranial Doppler middle cerebral artery blood flow velocity (FV) in 237 patients were analysed retrospectively. Indices describing cerebral autoregulation and pressure reactivity were calculated as correlation coefficients between 'slow waves' of mean FV and CPP (Mx) and ABP and ICP (PRx) over moving three minute periods. Data were averaged over multiple recordings made in the same patients and compared to clinical outcome at 6 months after head injury. All patients were sedated, paralysed and ventilated during the period when brain variables were monitored. Both PRx and Mx were well correlated with each other (R=0.58;p<0.00001). The absolute difference between Mx and PRx increased with greater ICP (R=0.27;p<0.0001) and with worse outcome (R=0.21;p<0.003). Both indices correlated positively with rising ICP and negatively with decreasing CPP, but the associations were stronger for PRx than Mx. Both indices were significantly correlated with outcome and were able to differentiate between fatal and non-fatal outcome with comparable power. However, where multiple regression was applied to outcome prediction, only mean ICP, age and PRx were retained as independent outcome predictors (R=0.35;p<0.00001). Although significantly inter-correlated in a group analysis, pressure-reactivity may be, in individual case, different from dynamic autoregulation. Pressure-reactivity seems to be more robust in head injured patients when continuous ICP monitoring is required.

Relevance of ICP and ptiO2 for indication and timing of decompressive craniectomy in patients with malignant brain edema

The exact effects of decompressive craniectomy on intracranial pressure (ICP) and cerebral tissue oxygenation (ptiO2) are still unclear. Therefore, we have monitored ICP and ptiO2 intra-operatively and correlated these values to different operative steps during craniectomy. ICP and ptiO2 values have been monitored both, simultaneously and continuously, in 15 patients with cerebral edema due to posttraumatic or postischemic brain swelling. Indications for craniectomy were an increase in ICP above 25 mmHg or a decrease in ptiO2 below 10 mmHg resistant to conservative treatment (e.g. mannitol, hyperventilation, adequate arterial blood oxygenation, etc.). In all cases, we performed a fronto-temporo-parietal craniectomy (15 x 12 cm) and dura enlargement with galea-periosteum. During craniectomy, monitoring of ICP and ptiO2 in the affected hemisphere was continued. Values were recorded and correlated with the different operative steps. We performed craniectomy according to our treatment protocol in 5 patients. Prior to surgery, mean ICP values were 25.6 mmHg (range: 23-29 mmHg), mean ptiO2 values were 5.9 mmHg (range: 2.4-9.5 mmHg), and mean CPP values were 66 mmHg (range: 60-70 mmHg). After removing the bone flap, ICP values dropped to physiological values (mean: 7.4 mmHg), whereas ptiO2 values increased only slightly (mean: 11 mmHg). Opening of the dura resulted in a further decrease of ICP (mean 4.8 mmHg) and an increase of ptiO2 to normal limits (mean: 18.8 mmHg). After skin closure, mean ICP was 6.8 mmHg and mean ptiO2 was 21.7 mmHg, respectively. We found a significant decrease of ICP after craniectomy (p<0.042) and after dura enlargement (p<0.039) as well as a statistically significant increase in ptiO2 after craniectomy (p<0.043) and after dura enlargement (p<0.041). As a large bone flap in decompressive craniectomy is essential for adequate ICP reduction, the results of the presented cases suggest that dura enlargement is the crucial step to restore adequate brain tissue oxygenation and that ptiO2 monitoring could be an important tool for timing craniectomy in the future.

Age, intracranial pressure, autoregulation, and outcome after brain trauma

The object of this study was to investigate whether a failure of cerebrovascular autoregulation contributes to the relationship between age and outcome in patients following head injury. Data obtained from continuous bedside monitoring of intracranial pressure (ICP), arterial blood pressure (ABP), and cerebral perfusion pressure (CPP = ABP - ICP) in 358 patients with head injuries and intermittent monitoring of transcranial Doppler blood flow velocity (FV) in the middle cerebral artery in 237 patients were analyzed retrospectively. Indices used to describe cerebral autoregulation and pressure reactivity were calculated as correlation coefficients between slow waves of systolic FV and CPP (autoregulation index [ARI]) and between ABP and ICP (pressure reactivity index [PRI]). Older patients had worse outcomes after brain trauma than younger patients (p = 0.00001), despite the fact that the older patients had higher initial Glasgow Coma Scale scores (p = 0.006). When age was considered as an independent variable, it appeared that ICP decreased with age (p = 0.005), resulting in an increasing mean CPP (p = 0.0005). Blood FV was not dependent on age (p = 0.58). Indices of autoregulation and pressure reactivity demonstrated a deterioration in cerebrovascular control with advancing age (PRI: p = 0.003; ARI: p = 0.007). An age-related decline in cerebrovascular autoregulation was associated with a relative deterioration in outcome in elderly patients following head trauma.