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Fulltext Longitudinal effects of common carotid artery stenosis on ocular hemodynamics assessed using laser speckle flowgraphy in a rabbit model

Ismail A, Chen HC, Faye I, Tang TB

Sci Rep, 2020 09 28;10(1):15829.
PMID: 32985560 DOI: 10.1038/s41598-020-72556-9

Real-time impairment of ocular blood flow (OBF) under common carotid artery stenosis (CCAS) has not been ascertained. We aimed to longitudinally assess the impact of CCAS on OBF using a rabbit model. About 75% stenosis was created by tying the common carotid artery with a plastic mandrel using a nylon suture. The plastic mandrel was gently removed, leaving a ligature. Neurological and behavioral assessments were recorded as the clinical indicator of stroke severity. With laser speckle flowgraphy, the pulse waveform parameters namely mean blur rate (MBR), blowout score (BOS), blowout time (BOT), rising rate, S1-area, falling rate (FR), S2-area, flow acceleration index (FAI), acceleration time index, resistive index (RI) and the difference between the maximum and minimum values of MBR (AC) were assessed in overall, vessel, and tissue regions of the optic nerve head (ONH). Longitudinally, BOS significantly increased until day 19 post-surgery, whereas FAI, RI, and AC significantly decreased. Beyond day 19, BOS, BOT, FR, FAI, RI, and AC significantly decreased. We defined two stages representing impaired vessel conditions, namely the vessel resistance phase, where BOS increases and FAI, RI, and AC decrease, and the vessel elasticity phase where BOS, BOT, FR, FAI, RI and AC decrease. These stages provide information about atherosclerosis, assessable non-invasively through the eye.

Matched MeSH terms: Hemodynamics/physiology
Comments on Point:Counterpoint: Sympathetic activity does/does not influence cerebral blood flow. When noradrenergic restraint of cerebral blood flow makes homeostatic sense

Prakash ES

J Appl Physiol (1985), 2008 10;105(4):1373.
PMID: 18938648 DOI: 10.1152/japplphysiol.zdg-8199.pcpcomm.2008
Matched MeSH terms: Hemodynamics*
Influence of stenosis on hemodynamic parameters in the realistic left coronary artery under hyperemic conditions

Kamangar S, Badruddin IA, Badarudin A, Nik-Ghazali N, Govindaraju K, Salman Ahmed NJ, et al.

Comput Methods Biomech Biomed Engin, 2017 Mar;20(4):365-372.
PMID: 27612619 DOI: 10.1080/10255842.2016.1233402

The current study investigates the hyperemic flow effects on heamodynamics parameters such as velocity, wall shear stress in 3D coronary artery models with and without stenosis. The hyperemic flow is used to evaluate the functional significance of stenosis in the current era. Patients CT scan data of having healthy and coronary artery disease was chosen for the reconstruction of 3D coronary artery models. The diseased 3D models of coronary artery shows a narrowing of >50% lumen area. Computational fluid dynamics was performed to simulate the hyperemic flow condition. The results showed that the recirculation zone was observed immediate to the stenosis and highest wall shear stress was observed across the stenosis. The decrease in pressure was found downstream to the stenosis as compared to the coronary artery without stenosis. Our analysis provides an insight into the distribution of wall shear stress and pressure drop, thus improving our understanding of hyperemic flow effect under both conditions.

Matched MeSH terms: Hemodynamics*
Fulltext Continuous spinal anaesthesia--early experience in University Hospital, Kuala Lumpur

Vijayan R, Chan L, Raveenthiran R

Med J Malaysia, 1995 Dec;50(4):401-10.
PMID: 8668064

Continuous spinal anaesthesia using the incremental technique was used in nineteen high risk patients with multiple medical problems, seventeen of whom were elderly, for lower limb orthopaedic and pelvic surgery. An intrathecal catheter (18G/28G) was inserted under local anaesthesia via the lumbar interspinous space. Spinal anaesthesia was induced with small incremental doses of 0.5% bupivacaine hydrochloride through the intrathecal catheter to achieve the level of analgesia required for surgery. The duration of surgery ranged from 45 to 300 minutes (mean + S.D 100 + 37 min). The initial volume of 0.5% bupivacaine required for surgery ranged from 0.8 ml-2.0 ml (1.2 + 0.7 ml) and the total volume ranged from 0.9 ml to 3.1 ml (mean + S.D 1.4 + 0.7 ml). Haemodynamic stability was well maintained perioperatively. Only two patients required 6 mg of ephedrine and 1 mg of aramine respectively for a greater than 25% reduction in systolic blood pressure with induction of spinal anaesthesia. Intrathecal morphine 0.1-0.3 mg was administered to 15 patients at the end of surgery for postoperative pain relief with good effect. One patient developed late respiratory depression from an inadvertent overdose of intrathecal morphine. No neurological sequelae were noted and no patient developed a postdural puncture headache. The use of the microcatheter was discontinued in the U.S.A and Australia following four case reports of cauda equina syndrome with this technique. Current opinion, however, is that the reported cauda equina syndrome was due to the neurotoxic effects of lignocaine 5% that was used and not due to the microcatheter per se. Continuous spinal anaesthesia is now used widely in Europe when cardiovascular stability is desired in poor risk patients undergoing lower limb and lower abdominal surgery.

Matched MeSH terms: Hemodynamics
The impact of group and individual training on hemodynamics, lipid metabolism, physical activity and quality of life in patients with high and very high cardiovascular risk

Isayeva G, Rieznik L, Buriakovska O, Vovchenko M, Emelyanova N, Shalimova A

Wiad Lek, 2019;72(12 cz 1):2315-2323.
PMID: 32124746

OBJECTIVE: Introduction: Despite significant advances in prevention and treatment, cardiovascular disease remains the main cause of mortality and disability in Europe. This is largely due to the low level of commitment to doctors' recommendations for drug treatment and lifestyle modification. The aim of the study was to compare the effectiveness of group and individual training in the basics of medical knowledge to control the main risk factors for cardiovascular disease in patients.
PATIENTS AND METHODS: Materials and methods: The study included 210 patients with high and very high cardiovascular risk. The first group consisted of 75 patients who studied at the School of Health 'Fundamentals of Healthy Lifestyle'. The second group consisted of 75 patients who were offered individual counseling. The control group consisted of 60 individuals. Patients in both groups were examined before and after the end of the course.
RESULTS: Results and conclusions: We conducted a general clinical examination, determined anthropometric parameters, blood pressure (BP), glucose, cholesterol and its fractions in the blood. It has been established that the group training of patients with high and very high cardiovascular risk in Schools of Health 'Fundamentals of Healthy Lifestyle' promotes better BP control, but does not significantly affect the lipid metabolism. Individual training for patients with high and very high cardiovascular risk leads to a significant reduction in BP levels, improved lipid metabolism, increased physical activity, and improved quality of life.

Matched MeSH terms: Hemodynamics
Baska mask versus endotracheal tube in laparoscopic cholecystectomy surgery: a prospective randomized trial

Ng CC, Sybil Shah MHB, Chaw SH, Mansor MB, Tan WK, Koong JK, et al.

Expert Rev Med Devices, 2021 Feb;18(2):203-210.
PMID: 33322949 DOI: 10.1080/17434440.2021.1865796

Background: Supraglottic airway devices have increasingly been used as the airway technique of choice in laparoscopic surgeries. This study compared the efficacy and safety of the Baska Mask with endotracheal tube (ETT) in patients undergoing elective laparoscopic cholecystectomy.Research design and methods: This single-center, prospective, randomized controlled trial recruited 60 patients aged 18-75 years with American Society of Anesthesiologists' classifications I to III. The time taken to achieve effective airway, number of attempts, ease of insertion, ventilation parameters, hemodynamics data, and pharyngolaryngeal complications were recorded.Results: The time taken to achieve effective airway was shorter for the Baska group (26.6 ± 4.7 vs. 47.2 ± 11.8 s; p

Matched MeSH terms: Hemodynamics
Fulltext Bimodal Data Fusion of Simultaneous Measurements of EEG and fNIRS during Lower Limb Movements

Al-Quraishi MS, Elamvazuthi I, Tang TB, Al-Qurishi M, Adil SH, Ebrahim M

Brain Sci, 2021 May 27;11(6).
PMID: 34071982 DOI: 10.3390/brainsci11060713

Electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) have temporal and spatial characteristics that may complement each other and, therefore, pose an intriguing approach for brain-computer interaction (BCI). In this work, the relationship between the hemodynamic response and brain oscillation activity was investigated using the concurrent recording of fNIRS and EEG during ankle joint movements. Twenty subjects participated in this experiment. The EEG was recorded using 20 electrodes and hemodynamic responses were recorded using 32 optodes positioned over the motor cortex areas. The event-related desynchronization (ERD) feature was extracted from the EEG signal in the alpha band (8-11) Hz, and the concentration change of the oxy-hemoglobin (oxyHb) was evaluated from the hemodynamics response. During the motor execution of the ankle joint movements, a decrease in the alpha (8-11) Hz amplitude (desynchronization) was found to be correlated with an increase of the oxyHb (r = -0.64061, p < 0.00001) observed on the Cz electrode and the average of the fNIRS channels (ch28, ch25, ch32, ch35) close to the foot area representation. Then, the correlated channels in both modalities were used for ankle joint movement classification. The result demonstrates that the integrated modality based on the correlated channels provides a substantial enhancement in ankle joint classification accuracy of 93.01 ± 5.60% (p < 0.01) compared with single modality. These results highlight the potential of the bimodal fNIR-EEG approach for the development of future BCI for lower limb rehabilitation.

Matched MeSH terms: Hemodynamics
Fulltext Hemodynamic effects resulting from a common carotid to middle cerebral bypass with varying degrees of proximal internal carotid stenosis

Sheau, Fung Sia, Yu, Zhang, Yi, Qian, Khairul Azmi Abd Kadir, Hazman Mohd Nor, Morgan, Michael Kerin

Neurology Asia, 2014;19(3):241-247.
MyJurnal

Objective: To investigate the degree of stenosis of the internal carotid artery required for continuous blood flow in an interposition vein bypass to the middle cerebral artery. Methods: Computational fluid dynamics techniques were used to investigate a case of common carotid to middle cerebral artery brain bypass with varying degrees of internal carotid artery stenosis. Blood flow patterns across the patient-specific brain bypass were evaluated. Results: Simulation found that for cross section stenosis of less than 60%, no flow occurred in the bypass graft. Further narrowing of the internal carotid artery increased flow linearly within the bypass graft. There was significant energy loss and pressure gradient difference between the proximal and distal anastomosis sites of the bypass.
Conclusion: Computational fluid dynamics helps us to quantify the flow distribution, wall shear stress and pressure gradient in brain bypass surgery. The angle of the distal anastomosis had no effect on hemodynamic indices, allowing this consideration to be ignored in modeling. This modeling technique is useful to estimate the required degree of stenosis in the artery that is to be occluded to ensure sustained flow in the bypass. This will be of importance where there is staged surgery with a time interval between the bypass and the definitive internal carotid artery occlusion.

Matched MeSH terms: Hemodynamics
Sedation with dexmedetomidine versus propofol during regional anaesthesia: comparing haemodynamic parameters, respiratory rates and offset times

Nadia, M.N., Samsul Johari, M.A., Muhammad, M., Raha, A.R., Nurlia, Y.

Journal of Surgical Academia, 2012;2(2):15-20.
MyJurnal

This study aimed to compare dexmedetomidine and propofol, in terms of haemodynamic parameters, respiratory rates and offset times, when used for sedation in patients undergoing elective orthopaedic and surgical procedures under regional anaesthesia. This was a prospective, randomised, single-blind study where 88 patients were recruited. Patients were randomised into two groups to receive either dexmedetomidine or propofol infusion. Central neuraxial blockade (spinal, epidural or combined spinal epidural) was performed. After ensuring an adequate block and stable haemodynamic parameters, dexmedetomidine was infused 15 minutes later at 0.4 μg/kg/hr, and propofol, at a target concentration of 2.5 μg/ml. Both drugs were titrated to achieve a bispectral index score of 70 before surgery commenced. Sedation level was monitored using the bispectral index score and assessed by the Observer Assessment of Alertness Scale score. Drug infusion was adjusted to maintain bispectral index scores ranging between 70-80 during surgery. Both groups showed reductions in mean arterial pressure and heart rate from baseline readings throughout the infusion time. However there was no significant reduction in the first 15 minutes from baseline (p > 0.05). Haemodynamic parameters and respiratory rate between both groups were not significantly different (p > 0.05). No patient demonstrated significant respiratory depression or SpO2 ≤ 95%. Offset times were also not significantly different between both groups (p = 0.594). There were no significant differences in haemodynamic parameters, respiratory rates and offset times between dexmedetomidine and propofol used for sedation in patients undergoing elective orthopaedic and surgical procedures under regional anaesthesia.

Matched MeSH terms: Hemodynamics
Fulltext Investigating brain activation and neural efficacy during simple arithmetic addition task in quiet and in noise: an fMRI study

Ng, Sok Bee, Ahmad Nazlim Yusoff, Teng, Xin Ling, Aini Ismafairus Abd. Hamid

Jurnal Sains Kesihatan Malaysia, 2014;12(1):23-33.
MyJurnal

Knowledge about the hemodynamic model that mediates synaptic activity and measured magnetic resonance signal is essential in understanding brain activation. Neural efficacy is a hemodynamic parameter that would change the evoked hemodynamic responses. In this work, brain activation and neural efficacy of the activated brain areas during simple addition task in two different backgrounds were studied using fMRI. The objectives were to determine the activated areas during the performance of arithmetic addition in quiet (AIQ) and noisy (AIN) background and to investigate the relationship between neural efficacy and height extent of activation for the respective areas. Eighteen healthy male participants performed simple arithmetic addition in quiet and in noise. Bilateral cerebellum, superior temporal gyrus (STG), temporal pole (TP) and supplementary motor area (SMA) were significantly (p < 0.05) activated during AIQ and AIN. Left middle frontal gyrus (L-MFG), right superior frontal gyrus (R-SFG), right superior orbital gyrus (R-SOG) and bilateral insula were more active in quiet as compared to in noise while the left middle cingulate cortex (L-MCC), left amygdala (L-AMG), right temporal pole (R-TP) and left cerebellum (L-CER) were more active in noise as compared to in quiet. The t value for most of the activated regions was found to be inversely proportional to the neural efficacy. Significant (p < 0.05) negative relationship between t value and neural efficacy were found for R-STG and bilateral cerebellum during AIQ, while for AIN, similar relationships were found in R-CER, R-STG and R-TP. This study suggests that while being significantly activated, the hemodynamic responses of these brain regions could have been suppressed by the stimulus resulting in an intensity decrease with increasing neural efficacy.

Matched MeSH terms: Hemodynamics
Comparison between the use of LMA™ and SLIPA™ in patients undergoing minor surgeries

Wan Rahiza, W.M., Nurlia, Y., Abd Rahman, I., Esa, K., Nadia, M.N., Raha, A. R.

Journal of Surgical Academia, 2012;2(1):8-13.
MyJurnal

Supraglottic airway devices have been used as safe alternatives to endotracheal intubation in appropriate types of surgery. This was a prospective, randomised, single blind study comparing the use of LMA™ and SLIPA™ in terms of ease of insertion, haemodynamic changes and occurrence of adverse effects (e.g. blood stains on the device upon removal and sore throat). A total of 62 ASA I or II patients, aged between 18 to 70 years were recruited for this study. Patients were randomised into two groups; LMA™ and SLIPA™ group. Following induction of anaesthesia, an appropriate sized LMA™ or SLIPA™ was inserted after ensuring adequate depth of anaesthesia. Anaesthesia was maintained with oxygen, nitrous oxide and sevoflurane. The ease of insertion was graded and haemodynamic changes were recorded at 2 minute intervals up to 10 minutes after insertion of the airway devices. The presence of blood stains upon airway device removal at the end of surgery and incidence of sore throat was also recorded. No difficult insertion was experienced in either of these devices. Insertion was either easy [LMA™ 87.1% versus SLIPA™ 80.6% (p = 0.49)] or moderate [LMA™ 12.9% versus SLIPA™ 19.4% (p = 0.16)]. Throughout the study period, the haemodynamic changes that occurred in both groups were not statistically different. Traces of blood were noted on the surface of the device in 9.7% of patients in the SLIPA™ group versus 6.5% of patients in the LMA™ group. The incidence of sore throat was recorded in 12.9% versus 19.4% of patients in the SLIPA™ and the LMA™ groups respectively. These findings were not statistically significant. In conclusion, this study showed no significant differences between the use of LMA™ and SLIPA™ in terms of ease of insertion, haemodynamic changes and adverse effects in patients undergoing minor surgical procedures.

Matched MeSH terms: Hemodynamics
Fulltext Pulsatile operation of a continuous-flow right ventricular assist device (RVAD) to improve vascular pulsatility

Ng BC, Kleinheyer M, Smith PA, Timms D, Cohn WE, Lim E

PLoS One, 2018;13(4):e0195975.
PMID: 29677212 DOI: 10.1371/journal.pone.0195975

Despite the widespread acceptance of rotary blood pump (RBP) in clinical use over the past decades, the diminished flow pulsatility generated by a fixed speed RBP has been regarded as a potential factor that may lead to adverse events such as vasculature stiffening and hemorrhagic strokes. In this study, we investigate the feasibility of generating physiological pulse pressure in the pulmonary circulation by modulating the speed of a right ventricular assist device (RVAD) in a mock circulation loop. A rectangular pulse profile with predetermined pulse width has been implemented as the pump speed pattern with two different phase shifts (0% and 50%) with respect to the ventricular contraction. In addition, the performance of the speed modulation strategy has been assessed under different cardiovascular states, including variation in ventricular contractility and pulmonary arterial compliance. Our results indicated that the proposed pulse profile with optimised parameters (Apulse = 10000 rpm and ωmin = 3000 rpm) was able to generate pulmonary arterial pulse pressure within the physiological range (9-15 mmHg) while avoiding undesirable pump backflow under both co- and counter-pulsation modes. As compared to co-pulsation, stroke work was reduced by over 44% under counter-pulsation, suggesting that mechanical workload of the right ventricle can be efficiently mitigated through counter-pulsing the pump speed. Furthermore, our results showed that improved ventricular contractility could potentially lead to higher risk of ventricular suction and pump backflow, while stiffening of the pulmonary artery resulted in increased pulse pressure. In conclusion, the proposed speed modulation strategy produces pulsatile hemodynamics, which is more physiologic than continuous blood flow. The findings also provide valuable insight into the interaction between RVAD speed modulation and the pulmonary circulation under various cardiovascular states.

Matched MeSH terms: Hemodynamics
Fulltext Preload-based Starling-like control of rotary blood pumps: An in-vitro evaluation

Mansouri M, Gregory SD, Salamonsen RF, Lovell NH, Stevens MC, Pauls JP, et al.

PLoS One, 2017;12(2):e0172393.
PMID: 28212401 DOI: 10.1371/journal.pone.0172393

Due to a shortage of donor hearts, rotary left ventricular assist devices (LVADs) are used to provide mechanical circulatory support. To address the preload insensitivity of the constant speed controller (CSC) used in conventional LVADs, we developed a preload-based Starling-like controller (SLC). The SLC emulates the Starling law of the heart to maintain mean pump flow ([Formula: see text]) with respect to mean left ventricular end diastolic pressure (PLVEDm) as the feedback signal. The SLC and CSC were compared using a mock circulation loop to assess their capacity to increase cardiac output during mild exercise while avoiding ventricular suction (marked by a negative PLVEDm) and maintaining circulatory stability during blood loss and severe reductions in left ventricular contractility (LVC). The root mean squared hemodynamic deviation (RMSHD) metric was used to assess the clinical acceptability of each controller based on pre-defined hemodynamic limits. We also compared the in-silico results from our previously published paper with our in-vitro outcomes. In the exercise simulation, the SLC increased [Formula: see text] by 37%, compared to only 17% with the CSC. During blood loss, the SLC maintained a better safety margin against left ventricular suction with PLVEDm of 2.7 mmHg compared to -0.1 mmHg for CSC. A transition to reduced LVC resulted in decreased mean arterial pressure (MAP) and [Formula: see text] with CSC, whilst the SLC maintained MAP and [Formula: see text]. The results were associated with a much lower RMSHD value with SLC (70.3%) compared to CSC (225.5%), demonstrating improved capacity of the SLC to compensate for the varying cardiac demand during profound circulatory changes. In-vitro and in-silico results demonstrated similar trends to the simulated changes in patient state however the magnitude of hemodynamic changes were different, thus justifying the progression to in-vitro evaluation.

Matched MeSH terms: Hemodynamics
Sudden Cardiac Death (SCD) - risk stratification and prediction with molecular biomarkers

Osman J, Tan SC, Lee PY, Low TY, Jamal R

J Biomed Sci, 2019 May 22;26(1):39.
PMID: 31118017 DOI: 10.1186/s12929-019-0535-8

Sudden cardiac death (SCD) is a sudden, unexpected death that is caused by the loss of heart function. While SCD affects many patients suffering from coronary artery diseases (CAD) and heart failure (HF), a considerable number of SCD events occur in asymptomatic individuals. Certain risk factors for SCD have been identified and incorporated in different clinical scores, however, risk stratification using such algorithms is only useful for health management rather than for early detection and prediction of future SCD events in high-risk individuals. In this review, we discuss different molecular biomarkers that are used for early detection of SCD. This includes genetic biomarkers, where the majority of them are genomic variants for genes that encode for ion channels. Meanwhile, protein biomarkers often denote proteins that play roles in pathophysiological processes that lead to CAD and HF, notably (i) atherosclerosis that involves oxidative stress and inflammation, as well as (ii) cardiac tissue damage that involves neurohormonal and hemodynamic regulation and myocardial stress. Finally, we outline existing challenges and future directions including the use of OMICS strategy for biomarker discovery and the multimarker panels.

Matched MeSH terms: Hemodynamics
A case of surgically resected cardiac rhabdomyoma with progressive left ventricular outflow tract obstruction

Mohammed F, Tan GC, Hor KN, Arnold M, Wong YP

Cardiovasc. Pathol., 2020 05 12;49:107226.
PMID: 32574866 DOI: 10.1016/j.carpath.2020.107226

Cardiac rhabdomyoma is the most prevalent cardiac tumors in the pediatric population, in close association with tuberous sclerosis complex. It is usually detected antenatally or postnatally by echocardiography. Clinical presentations depend greatly on the size and position of the tumor mass. Interestingly, rhabdomyoma has a propensity to regress spontaneously and is not usually operated upon, unless the patient becomes hemodynamically compromised. Herein, we report an unusual case of surgically treated cardiac rhabdomyoma in a baby boy presented at birth with a progressive enlarging intraventricular mass, complicated with left ventricular outflow tract obstruction 7 weeks later. Histopathological examination of the intracardiac mass revealed sheets of tumor cells with spider-like morphology (known as "spider cells"), confirmed the diagnosis of rhabdomyoma. Close disease monitoring of patient's hemodynamic status in a newly diagnosed cardiac rhabdomyoma is inevitable as the tumor, although rare, may progress.

Matched MeSH terms: Hemodynamics
Renal functional & haemodynamic changes following acute unilateral renal denervation in Sprague Dawley rats

Salman IM, Sattar MA, Abdullah NA, Ameer OZ, Hussain FB, Hye Khan MA, et al.

Indian J Med Res, 2010 Jan;131:76-82.
PMID: 20167977

Regulation of renal function and haemodynamics are under a direct control from the renal sympathetic nerves and renal denervation produces overt diuresis and natriuresis in several mammalian species. However, the inter-related series of changes in renal function and haemodynamics following acute renal denervation (ARD) is not fully understood. Thus, we aimed to investigate and relate the changes in renal function and haemodynamics following acute unilateral renal denervation in anaesthetized Sprague Dawley (SD) rats.

Matched MeSH terms: Hemodynamics
Fulltext Comparison of the Effects of Dexmedetomidine on the Induction of Anaesthesia Using Marsh and Schnider Pharmacokinetic Models of Propofol Target-Controlled Infusion

Wan Hassan WMN, Tan HS, Mohamed Zaini RH

Malays J Med Sci, 2018 Feb;25(1):24-31.
PMID: 29599632 MyJurnal DOI: 10.21315/mjms2018.25.1.4

Background: The study aimed to determine the effects of dexmedetomidine on the induction of anaesthesia using different models (Marsh and Schnider) of propofol target-controlled infusion (TCI).
Methods: Sixty-four patients aged 18-60 years, American Society of Anaesthesiologists (ASA) class I-II who underwent elective surgery were randomised to a Marsh group (n= 32) or Schnider group (n= 32). All the patients received a 1 μg/kg loading dose of dexmedetomidine, followed by TCI anaesthesia with remifentanil at 2 ng/mL. After the effect-site concentration (Ce) of remifentanil reached 2 ng/mL, propofol TCI induction was started. Anaesthesia induction commenced in the Marsh group at a target plasma concentration (Cpt) of 2 μg/mL, whereas it started in the Schnider group at a target effect-site concentration (Cet) of 2 μg/mL. If induction was delayed after 3 min, the target concentration (Ct) was gradually increased to 0.5 μg/mL every 30 sec until successful induction. The Ct at successful induction, induction time, Ce at successful induction and haemodynamic parameters were recorded.
Results: The Ct for successful induction in the Schnider group was significantly lower than in the Marsh group (3.48 [0.90] versus 4.02 [0.67] μg/mL;P= 0.01). The induction time was also shorter in the Schnider group as compared with the Marsh group (134.96 [50.91] versus 161.59 [39.64]) sec;P= 0.02). There were no significant differences in haemodynamic parameters and Ce at successful induction.
Conclusion: In the between-group comparison, dexmedetomidine reduced the Ct requirement for induction and shortened the induction time in the Schnider group. The inclusion of baseline groups without dexmedetomidine in a four-arm comparison of the two models would enhance the validity of the findings.

Matched MeSH terms: Hemodynamics
Fulltext Symptomatic presentation of carotid sinus hypersensitivity is associated with impaired cerebral autoregulation

Tan MP, Chadwick TJ, Kerr SR, Parry SW

J Am Heart Assoc, 2014 Jun;3(3):e000514.
PMID: 24947997 DOI: 10.1161/JAHA.113.000514

Carotid sinus hypersensitivity (CSH) is associated with syncope, unexplained falls, and drop attacks in older people but occurs asymptomatically in 35% of community-dwelling elders. We hypothesized that impaired cerebral autoregulation is associated with the conversion of asymptomatic CSH to symptomatic CSH. We therefore conducted a case-control study evaluating individuals with CSH with and without the symptoms of syncope or unexplained falls, as well as non-CSH controls, to determine whether the blood pressure and heart rate changes associated with CSH are associated with symptoms only when cerebral autoregulation is altered.

Matched MeSH terms: Hemodynamics/physiology
Anatomy and Physiology of Left Ventricular Suction Induced by Rotary Blood Pumps

Salamonsen RF, Lim E, Moloney J, Lovell NH, Rosenfeldt FL

Artif Organs, 2015 Aug;39(8):681-90.
PMID: 26146861 DOI: 10.1111/aor.12550

This study in five large greyhound dogs implanted with a VentrAssist left ventricular assist device focused on identification of the precise site and physiological changes induced by or underlying the complication of left ventricular suction. Pressure sensors were placed in left and right atria, proximal and distal left ventricle, and proximal aorta while dual perivascular and tubing ultrasonic flow meters measured blood flow in the aortic root and pump outlet cannula. When suction occurred, end-systolic pressure gradients between proximal and distal regions of the left ventricle on the order of 40-160 mm Hg indicated an occlusive process of variable intensity in the distal ventricle. A variable negative flow difference between end systole and end diastole (0.5-3.4 L/min) was observed. This was presumably mediated by variable apposition of the free and septal walls of the ventricle at the pump inlet cannula orifice which lasted approximately 100 ms. This apposition, by inducing an end-systolic flow deficit, terminated the suction process by relieving the imbalance between pump requirement and delivery from the right ventricle. Immediately preceding this event, however, unnaturally low end-systolic pressures occurred in the left atrium and proximal left ventricle which in four dogs lasted for 80-120 ms. In one dog, however, this collapse progressed to a new level and remained at approximately -5 mm Hg across four heart beats at which point suction was relieved by manual reduction in pump speed. Because these pressures were associated with a pulmonary capillary wedge pressure of -5 mm Hg as well, they indicate total collapse of the entire pulmonary venous system, left atrium, and left ventricle which persisted until pump flow requirement was relieved by reducing pump speed. We suggest that this collapse caused the whole vascular region from pulmonary capillaries to distal left ventricle to behave as a Starling resistance which further reduced right ventricular output thus contributing to a major reduction in pump flow. We contend that similar complications of manual speed control also occur in the human subject and remain a major unsolved problem in the clinical management of patients implanted with rotary blood pumps.

Matched MeSH terms: Hemodynamics*
Alfentanil for intubation under halothane anaesthesia in children

NG KP, Wang CY

Paediatr Anaesth, 1999;9(6):491-4.
PMID: 10597551

Intubating conditions under halothane anaesthesia aided with alfentanil 20 micrograms.kg-1 were compared with suxamethonium 2 mg.kg-1 in 40 children presenting for day dental procedures. The condition of vocal cords, jaw relaxation and presence of movement and coughing were scored to give the overall intubating conditions. Successful intubation was achieved in 100% of the suxamethonium group and 94.7% of the alfentanil group. The cardiovascular response to intubation was attenuated in the alfentanil group. Some 43.7% of those receiving suxamethonium developed myalgia the day after surgery compared with 0% in the alfentanil group (P < 0.01).

Matched MeSH terms: Hemodynamics/drug effects

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