A Study to Observe Pulse Pressure Variation after Induction with Propofol for General Anesthesia

Background and Aims: Pulse pressure variation (PPV) is a reliable and predictive dynamic parameter presently being utilized for fluid responsiveness. In the operating room, fluid administration based on PPV monitoring helps the physician in deciding whether to volume resuscitate or use interventions in patients undergoing surgery. Propofol is an intravenous induction agent which lowers blood pressure. There are multiple causes such as depression in cardiac output, and peripheral vasodilatation for hypotension. We undertook this study to observe the utility of PPV as a guide to fluid therapy after propofol induction. Primary outcome of our study was to monitor PPV as a marker of fluid responsiveness for the hypotension caused by propofol induction. Secondary outcome included the correlation of PPV with other hemodynamic parameters like heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP);after induction with propofol at regular interval of time. Methods: A total number of 90 patients were recruited. Either of the radial artery was then cannulated under local anaesthesia with 20G VygonLeadercath arterial cannula and invasive monitoring transduced. A baseline recording of heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and PPV was then recorded. Patients were then induced with predetermined doses of propofol (2 mg/kg) and recordings of HR, SBP, DBP, and PPV were taken at 5, 10 and 15 minutes. Results: Intraoperatively, PPV was significantly higher at 5 minutes and significantly lower at 15 minutes after induction. It was observed that there were no statistically significant correlations between PPV and SBP or DBP. PPV was strongly and directly associated with HR. Conclusion: We were able to establish that PPV predicts fluid responsiveness in hypotension caused by propofol induction;and can be used to administer fluid therapy in managing such hypotension. However, PPV was not directly correlated with hypotension subsequent to propofol administration.

THE EFFECTS OF PULSE BIAS VOLTAGE AND N_2 PARTIAL PRESSURE ON TiAlN FILMS OF ARC ION PLATING (AIP)

Owing to the characteristics of arc ion plating(AIP) technique, the structure and composition of TiAlN films can be tailored by controlling of various parameters such as compositions of target materials, N2 partial pressure, substrate bias and so on. In this study, several titanium aluminum nitride films were deposited on 1Cr11Ni2W2MoV steel for compressor blade of areo-engine under different d.c pulse bias voltage and nitrogen partial pressure. The effects of substrate pulse bias and nitrogen partial pressure on the deposition rate, droplet formation, microstruture and elemental component of the films were investigated.

Nanosecond Repetitively Pulsed Dielectric Barrier Discharge in Air at Atmospheric Pressure

Dielectric barrier discharge （DBD） between two cylindrical glass containers with salt water generated by a nanosecond repetitively pulsed power generator is reported. The electrical parameters, luminous images and spectrum diagnosis are presented. It is shown that the DBD possesses a large discharge current and an intense optical emission from the nitrogen second positive system below 400 nm. The gas temperature remains very close to room temperature regardless of pulse polarity. Luminous photographs with a short exposure time down to 2 ns indicate that no filament is observed and the discharge is homogeneous.

Effects of body mass index on intraocular pressure and ocular pulse amplitude

AIM: To investigate the effects of body mass index (BMI) on intraocular pressure (IOP) and ocular pulse amplitude(OPA). METHODS: Totally 140 healthy individuals without any systemic diseases were included in the study. BMI (kg/m2) was calculated for every individual. IOP and OPA were measured with Pascal Dynamic contour tonometer (DCT). Blood pressure was also measured along with the DCT. The patients were divided into three groups according to BMI as: Group1, BMI<25; Group2, 25≤BMI<30; Group3, BMI≥30. Mean values of IOP, OPA, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were used in statistical analysis.RESULTS: In Group1, the means of IOP, OPA, were 16.8±2.3mmHg, 2.7±0.7mmHg respectively; and SBP, DBP were 120.0±6.1mmHg, and 77.4±5.6mmHg respectively. In group2, the mean IOP, OPA, SBP, and DBP were found to be 16.6±2.1mmHg, 2.4±0.7mmHg, 121.7±5.3mmHg, and 79.5±4.9mmHg respectively. In group3, the mean IOP, OPA, SBP, and DBP were found to be 17.3±1.7mmHg, 2.1±0.7mmHg, 122.4±5.7mmHg, and 79.7±5.2mmHg respectively. There were no statistically significant difference between groups in terms of IOP, SBP and DBP, while OPA values were significantly lower in group3 (P=0.001). CONCLUSION: Decreased OPA values in individuals with higher BMI may indicate that subjects with higher BMI have lower choroidal perfusion and lower ocular blood flow.

A novel variable polarity welding power based on high-frequency pulse modulation

A new type of variable polarity welding power modulated with high-frequency pulse current is developed. Series of high-frequency pulse current is superimposed on direct-current-electrode-negative （DCEN）, which can improve the crystallization process in the weld bead as a result of the electromagnetic force generated by pulse current. Digital signal processor （DSP） is used to realize the closed-loop control of the first inverter, variable polarity output of the second inverter and high-frequency pulse current superposition.

Effects of Oxygen Concentration on Pulsed Dielectric Barrier Discharge in Helium-Oxygen Mixture at Atmospheric Pressure

In this work the effects of O_2 concentration on the pulsed dielectric barrier discharge in helium-oxygen mixture at atmospheric pressure have been numerically researched by using a one-dimensional fluid model in conjunction with the chosen key species and chemical reactions.The reliability of the used model has been examined by comparing the calculated discharge current with the reported experiments. The present work presents the following significant results. The dominative positive and negative particles are He_2~＋ and O_2^-, respectively, the densities of the reactive oxygen species（ROS） get their maxima nearly at the central position of the gap, and the density of the ground state O is highest in the ROS. The increase of O_2 concentration results in increasingly weak discharge and the time lag of the ignition. For O_2 concentrations below 1.1%,the density of O is much higher than other species, the averaged dissipated power density presents an evident increase for small O_2 concentration and then the increase becomes weak. In particular,the total density of the reactive oxygen species reaches its maximums at the O_2 concentration of about 0.5%. This characteristic further convinces the experimental observation that the O_2 concentration of 0.5% is an optimal O_2/He ratio in the inactivation of bacteria and biomolecules when radiated by using the plasmas produced in a helium oxygen mixture.

Effect of music on blood pressure, pulse rate and respiratory rate of asymptomatic individuals: A randomized controlled trial

A slight reduction of blood pressure and heart rate can reduce the risk of developing cardiovascular disease. Maintenance of the respiratory rate within the normal range has also being identified as crucial for a healthy heart. Use of Indian and western music have been considered among many preventive programmes for long time in order to risk reduction associated with cardio vascular diseases. Therefore the aim of this study is to describe the effect of Indian classical music on systolic and diastolic blood pressure, pulse rate and respiratory rate in asymptomatic individuals aged 45 to 65 years. Methodology: A community based randomized intervention study was conducted in 252 asymptomatic individuals. The study group (n = 127) listened to a music based on Indian classical system (entire track of 22 minutes). The control group (n = 125) was kept silent for a similar time period. Systolic and diastolic blood pressure, pulse rate and respiratory rate of each study participant were monitored before and after the intervention. Results: Statistically significant reduction in systolic blood pressure (8.53 mmHg), diastolic blood pressure (5.8 mmHg), pulse rate (5.16 breaths per minute) and respiratory rate (2.55 per minute) were observed in the study group after listening to the music (p < 0.01). In the control group, changes observed during the period of intervention were not significant (p > 0.05). The reduction was independent of gender, age, education level, practicing a mind relaxation technique and preferred type of music of the participant. Conclusions: Listening to Indian classical music for about 22 minutes significantly reduced systolic and diastolic blood pressure, pulse rate and respiratory rate of asymptomatic individuals. Hence, music may have a potential benefit in cardio vascular disease preventive programmes.

Arterial Pulse Pressure Variation versus Central Venous Pressure as a Predictor for Fluid Responsiveness during Open Major Abdominal Operations

Introduction: Fluid resuscitation is the cornerstone in the management of hemodynamically unstable patients. Dynamic parameters of fluid responsiveness, like pulse pressure variation, have the advantage of being more reliable index for fluid management. Objective: The aim of our study was to compare between arterial pulse pressure variation (PPV) versus central venous pressure (CVP) as a predictor for fluid responsiveness during major open abdominal operations. Patients and Methods: 60 adult patients under general anesthesia with mechanical ventilation underwent open major abdominal surgical procedures were included in our prospective randomized controlled study. Intravenous fluid was infused and monitored by CVP in control group or by PPV in the other group. Hemodynamic variables (heart rate, invasive blood pressure, PPV and CVP) were measured at baseline after anesthesia induction and every 10 min, during first hour of operation, and then every 15 min, till end of surgery. Blood loss and total i.v. fluid & blood transfusion given to patients were recorded and compared between two groups intraoperatively. Results: Patients in the PPV group required more intraoperative fluid and blood transfusion than patients in CVP group to achieve more stable hemodynamic parameters. The fall in blood pressure (>20% of baseline) and increase in heart rate are more common in CVP group (p Conclusion: PPV is a better predictor and a good guide for fluid responsiveness. More stable hemodynamic variables are observed in PPV group.

Noninvasive method for determining blood pressure and contours of arterial and volume pulses

A noninvasive method for monitoring blood pressure, based on the principles established by Riva-Rocci and Korotkoff (K), is described;it furnishes, after a single compression-deflation cycle of the arm-encircling cuff, values of sys-tolic and diastolic blood pressures as well as the contours of the brachial arterial pulse and the corresponding volume pulse. K-sounds are detected by a single microphone situated in the cubital fossa, and the time-varying cuff pressure P(t) is read by a piezoresistive pressure sensor. The behavior of P(t) during deflation is resolved into two parts, P(t)=p(t)+b(t);p is a train of posi-tive going pulses (arising from arterial pulsa-tions), whereas b is a slowly changing baseline. Noise pulses in the microphone output are re-jected by using the observation that the first few K-sounds are emitted when p is close to a maxi-mum, and the last few when dp/dt is close to a maximum. The performance of the instrument is illustrated by showing how it copes with ambi-ent noise and involuntary manual perturbations of P, and by presenting contours of various pulses.

Generation of X-ray Emission in Repetitive Nanosecond-pulse Discharge at Atmospheric Pressure

Pulsed discharges can generate high power densities and high equivalent electric fields in plasma to emit X-rays,which is closely related to discharge mechanism.In this paper,discharge characteristics and X-ray emission of typical nanosecond-pulse discharges(corona,diffuse,spark or arc)are reviewed.Especially,the diffuse discharges are observed at pulse repetition frequencies up to 1 kHz.Factors influencing the discharge characteristics and X-ray emission are analyzed,such as the gap spacing,parameters of the applied pulse(amplitude,pulse repetition frequency),anode and cathode materials,and curvature radius of cathode.It is concluded that the maximum X-ray intensity is obtained in a diffuse discharge,and the X-ray intensity is affected by the pulse repetition frequency,applied voltage,anode material,and curvature radius of cathode.For example,X-ray intensity increases with the pulse repetition frequency and the atomic numbers of the anode material,but it decrease with the increase of curvature radius.It is also shown that the cathode material has no obvious influence on the X-ray intensity.

ACUPUNCTURE AT NEIGUAN POINT FOR TREATMENT OF 106 CASES OF LOW PULSE PRESSURE SYNDROME

In spite of normal mean aterlal pressure,decrease of pulse pressure can induce a seriesof clinical symptoms,which is termed as low pulse pressure syndrorne.Acupuncture at bilateralNeiguan（PC 6）is Capable of raising systolic pressure, lowering diastolic pressure, increasing pulsepressure difference and eliminating corresponding symptoms.The effective rate was more than 92％in this observation.

Generation of Atmospheric Pressure Plasma by Repetitive Nanosecond Pulses in Air Using Water Electrodes

Dielectric barrier discharge （DBD） excitated by pulsed power is a promising method for producing nonthermal plasma at atmospheric pressure. Discharge characteristic in a DBD with salt water as electrodes by a home-made unipolar nanosecond-pulse power source is presented in this paper. The generator is capable of providing repetitive pulses with the voltage up to 30 kV and duration of 70 ns at a 300 Ω resistive load. Applied voltage and discharge current are measured under various experimental conditions. The DBD created between two liquid electrodes shows that the discharge is homogeneous and diffuse in the whole discharge regime, Spectra diagnosis is conducted by an optical emission spectroscopy. The air plasma has strong emission from nitrogen species below 400 nm, notably the nitrogen second positive system.

Amine-containing film deposited in pulsed dielectric barrier discharge at a high pressure and its cell adsorption behaviours

With monomer allylamine, amine-containing functional films were prepared in alternative current pulsed dielectric barrier discharge （DBD） at a high pressure. This paper analyses in detail the film properties and structures, such as hydrophilicity, compounds and microstructures as well as amine density by the water contact angle, Fourier transform infrared spectroscopy, atomic force microscopy, and ultraviolet-visible measurement. The influence of discharge param- eters, in particular applied power, on amine density was investigated. As an application the cell adsorption behaviours on plasma polymerization films was performed in-vitro. The results show that at a high pressure pulsed DBD plasma can polymerize films with sufficient amine group on surface, through which the very efficient cell adsorption behaviours was demonstrated, and the high rate of cell proliferation was visualized.

Characteristics of SF_6 Switch with a Small Gap under High Pressure and Nanosecond Pulse

Structural design and tests on the characteristics of the SF6 gas switch with a small gap are presented. This kind of switch often works under high pressure and nanosecond pulse for getting pulse with faster risetime. The breakdown voltage and breakdown delay of a number of switches with different geometries, gas pressures and pulse waveforms were investigated. Experimental results suggested that the breakdown voltage increases linearly with the gas pressure, and the breakdown delay decreases with an increase in the gas pressure and a reduction in the gap distance of the switch under the same applied pulse. By using this kind of switch with a gap of 3 mm as a peaking switch, a pulse generator can provide an output voltage with a peak voltage of 300 kV and a risetime of 3 ns on a resistance load of 150Ω.

Influence of Ambient Gas and Oxygen Pressure on Nd∶LuVO_4 Films Grown by Pulsed Laser Deposition

The （ 200 ） dominated Nd： LuVO4 films were fabricated successfully on polished SlOE under different ambient gases and different oxygen pressures. By XRD, it is shown that a film with good crystallization is deposited under oxygen and the optimal pressure is 20 Pa. The surface morphology of Nd：LuVO4 films was observed by AFM, and it is found that oxygen pressure influences the surface morphology of Nd ：LuVO4 films. The ratio of content of Nd：LuVO4 films was estimated according to the yields of Lu and V by using RBS spectra, this ratio is in good agreement with the target composition. The effective index refractive of every mode is 2.0044, 1.7098, measured by prism coupler method.

Investigation of Nanosecond Pulsed Discharge and Its Audio Characteristics in Atmospheric-pressure Air

There was no well-resolved mechanism of audible noise caused by corona discharge on UHV transmission lines. Hence we measured the sound pressure of pulsed discharges between needle-plane electrodes under different discharge conditions in air, for revealing the intrinsic relationship between discharge and its audible noise(AN). The relationship between discharge parameters and audio characte- ristics was drawn from the analysis of the electric and sound signals obtained in experiments. Experiment results showed that nanosecond pulsed discharges produce the sound pressure with a microsecond pulse lagging behind the discharge pulse in their waveforms. The peak value of the sound pulse decreases and its high frequency component gradually attenuates, when the measuring distance from discharges increases. The sound pulses correlate with the discharge current and voltage significantly, especially the current. The audible noise produced by repetitive pulsed discharge increases with the strength, duration, and pulse repetition rate of discharge.

The pulse pressure in a premature infant less than 37 weeks gestational age with a patent ductus arteriosus

A widened pulse pressure could be a sign of a patent ductus arteriosus in an infant. This is defined as a difference between systolic and diastolic blood pressure of greater than 15 to 25 mmHg, in premature infants and greater than 25 mmHg in term infants [1]. It is thought that diastolic runoff from blood flow shunting across the aorta to the pulmonary artery, through the patent ductus arteriosus, will produce a lower diastolic pressure and therefore widen the pulse pressure in the affected infant [1]. In our retrospective chart review, 116 premature infants were identified with a patent ductus arteriosus and compared to 42 premature infants without a patent ductus arteriosus. The blood pressures obtained were recorded for the first 7 days of life of the patients. Our studies revealed that premature infants with a patent ductus arteriosus had a mean pulse pressure of19 mmHg (p-value 0.129) when compared to infants without a patent ductus arteriosus,16 mmHg, on day 1 of life. The mean pulse pressures were ~20 mmHg in both groups on days 2 - 3. On days 4 - 7 mean pulse pressures were greater than20 mmHg for both groups (p-values 0.35, 0.19, 0.74, 0.8). It was noticed that mean pulse pressures in the patent ductus arteriosus group were within 0-4 mmHg when compared to the group without a patent ductus arteriosus and therefore not clinically relevant or statistically significant.

Pulse Pressure as a Risk Factor of Atrial Fibrillation in Black African Elderly Patients

Objective: The aim of this study was to show the prognostic role of High Pulse Pressure (PP) in the occurrence of atrial fibrillation in Black African elderly patients. Materials and Methods: In a comparative retrospective study related to 2000 patients admitted to the Institute of Cardiology of Abidjan, from January 1991 to December 2010 for atrial fibrillation, we matched pulse pressure and atrial fibrillation in Black African elderly patients. Results: The mean age of patients was 65 ± 10 years. Patients with high pulse pressure were 4.8 times more at risk to present atrial fibrillation than those with normal pulse pressure. The threshold of high risk pulse pressure was 65 mmHg. Conclusion: Pulse pressure is a factor of bad prognosis of atrial fibrillation in Black African elderly patients.

Prognostic Role of Pulse Pressure in the Acute Phase of Myocardial Infarction

Objective: Pulse pressure is a cardiovascular risk factor. The aim of our study was to assess the short and medium term prognosis of myocardial infarction in the African black having a high pulse pressure. Methods: We performed a comparative retrospective study of 200 patients hospitalized in the Cardiology Institute of Abidjan. The first group (100 patients) had a high pulse pressure (≥60 mmHg). The second (100 patients) had normal pulse pressure (≤60 mmHg). The primary outcome was mortality. Secondary endpoints were represented by hemodynamic complications, rhythmic and conduction disturbances. Both groups of patients were matched. The matching is performed by socio-demographic criteria, the seat of necrosis and cardiovascular risk factors. The authors explained the choice of 60 mmHg as references because in all their studies they have realized that it is from 60 mmHg pulse pressure morbid events that occur in prospective studies and retrospective studies in stiffness of the great arteries is responsible for all these events. Pulse pressure is in itself, an independent cardiovascular risk factor in systolic blood pressure, diastolic blood pressure when associated with myocardial infarction, it becomes from 60 mmHg poor prognostic factor especially in the acute phase. Results: The mean age was 54.46 ± 10.10 years for patients with normal pulse pressure and 52.32 ± 10.89 years in patients with high pulse pressure. Patients with elevated pulse pressure were twice as left ventricular failure (Chi2 = 3.71;P = 0.048 = 2 OR 95% CI = 0.93 to 4.29). These patients had an ejection fraction and fractional shortening double bass (Chi2 = 31.23 P = 0.00001, OR = 2.2 95% CI 0.8 to 17.4) 10 mmHg for increased pulse pressure we observed an average growth of 18% mortality rate. Mortality was three times higher in patients with elevated pulse pressure (Khi2 = 15, 06 ddl = 1 P = 0.0001 OR = 3.34 95% CI 1.72 to 6.52). Conclusion: The high pulse pressure represented an independent poor prognostic factor in the acute phase of myocardial infarction in the black African.

Interaction between Antihypertensive Therapy Class and Pulse Pressure on Outcomes Following Acute Ischemic Stroke

Goal: The effect of pulse pressure and interactions with type of antihypertensive therapy on mortality after acute ischemic stroke has not been previously evaluated. Materials and Methods: A retrospective cohort study was conducted to evaluate the independent and interactive effects of pulse pressure and antihypertensive class (specifically angiotensin converting enzyme inhibitor/angiotensin type 1 receptor blocker, or beta blocker) on mortality following acute ischemic stroke. Findings/Conclusions: 343 patients were identified with 49 months of follow-up. Baseline pulse pressure was 64 mmHg and age was 66.5 years. Patients were divided at a pulse pressure of 70. Patients with pulse pressure ≥ 70 were older (p < 0.001) and had higher comorbid vascular burden (p = 0.031) than those with pulse pressure < 70. Pulse pressure did not remain a significant predictor of follow-up mortality after adjustment for baseline comorbidities. Angiotensin converting enzyme inhibitor/angiotensin type 1 receptor blocker based therapy was associated with lower follow-up mortality when beta blocker was not used in pulse pressure < 70 group (odds ratio 0.07, 95% confidence interval 0.01 - 0.48). Prospective analysis will be needed to confirm the protective effect of angiotensin converting enzyme inhibitor/angiotensin type 1 receptor blocker based on pulse pressure in acute ischemic stroke.