Taking the pressure out of atomisation

The combination of a gas-stabilised melt stream and low-pressure water atomisation can produce very fine powders at lower cost...     

Automatic measurement of arterial pressure

PURPOSE: To identify patients with lymphoma at risk for tumor lysis after chemotherapy. PATIENTS AND METHODS: The case records of 102 patients receiving combination chemotherapy for non-Hodgkin's lymphoma (intermediate to high-grade histology) were reviewed. Patients were considered to have "laboratory tumor lysis" if two of the following metabolic changes occurred within 4 days of treatment: a 25% increase in the serum phosphate, potassium, uric acid, or urea nitrogen concentrations, or a 25% decline in the serum calcium concentration. "Clinical tumor lysis" was defined as laboratory tumor lysis plus one of the following: a serum potassium level greater than 6 mmol/L, a creatinine level greater than 221 mumol/L, or a calcium level less than 1.5 mmol/L, the development of a life-threatening arrhythmia, or sudden death. RESULTS: Laboratory tumor lysis occurred in 42% of patients and clinical tumor lysis in 6%. There was no statistical difference in the frequency of either tumor lysis syndrome among lymphoma subgroups. Clinical tumor lysis occurred more frequently in patients with pretreatment renal insufficiency (serum creatinine level greater than 132 mumol/L) than in patients with normal renal function (36% versus 2%; p = 0.01). The development of azotemia correlated with high pretreatment serum lactate dehydrogenase concentrations (p < 0.01; r2 = 0.11). CONCLUSION: Clinically significant tumor lysis is a rare occurrence in patients with lymphoma when they are receiving allopurinol. However, tumor lysis can occur in patients with all types of moderate to high-grade non-Hodgkin's lymphoma. Patients with a high serum lactate dehydrogenase level or renal insufficiency are at increased risk for metabolic complications after chemotherapy and should be closely monitored.     

Optimal pulmonary arterial blood pressure

Based on the principle of minimum power, a mathematical model of the functional state of the pulmonary circulatory and respiratory systems is presented. The optimization model minimizes the power expended by the right heart and respiratory muscles. The pulmonary diffusing capacity control mechanism is considered. Mean pulmonary arterial blood pressure and ventilation are determined depending on oxygen transport parameters for man under normal and chronic pathological conditions. Theoretical results are compared with clinical data.     

Elderly patients during an ambulatory neurological consultation

To assess current trends in the disclosure of cancer, we studied patients with primary lung cancer. Ninety-nine of 101 surgical patients (98.0%) and 96 of 128 non-surgical patients (75.0%) had been informed of their illness. Family members of 2 surgical patients refused to allow disclosure due to concerns about mental intolerance. Reasons for non-disclosure to non-surgical patients ranged from rejection by family members (29 patients) to a lack of ability to understand (3 patients). No mental problems were observed after disclosure. All but 11 patients were informed of their cancers by their physicians. Decisions regarding disclosure were not related to the pathological type or clinical stage of the cancer. For example, small cell carcinoma did not influence methods of or decisions concerning disclosure. Among non-surgical patients, the frequency of disclosure decreased with aging. However, no clear-cut factor appeared to influence the disclosure of metastatic sites. Views about informed consent are still at a transitional stage in Japan. The doctrine that patients have the right to be informed of their cancers and to choose their treatment has not always been the best policy in practice. Nevertheless, it seems desirable that approaches to disclosure adequately reflect the special needs of each patient and provide as much information as possible to allow each patient to make an accurately informed decision about treatment options. Such approaches would foster better relationships between physicians and their patients and relieve physicians from pressure to tell a medical lie.     

Power spectral analysis of electromyographic and systemic arterial pressure signals during fentanyl-induced muscular rigidity in the rat

We have measured electromyographic (EMG) and systemic arterial pressure (SAP) signals during fentanyl-induced muscular rigidity in adult male Sprague-Dawley rats anaesthetized initially with ketamine 120 mg kg-1 i.p. during controlled ventilation. Fentanyl 100 micrograms kg-1 i.v. induced significant increase in EMG activity, recorded from the sacrococcygeus dorsi lateralis muscle. Power spectral analysis revealed that this was produced by an increase in the root mean square and a decrease in the mean power frequency values of the signals, signifying recruitment and synchronous activation of motor units. Together with transient hypotension and bradycardia, power spectral analysis of the SAP signals demonstrated a reduced but maintained power density of the frequency components that represent respiratory, baroreceptor and vasomotor activities. All these effects were only demonstrated unequivocally in rats maintained by i.v. infusion of ketamine until 10 min before the administration of fentanyl. We conclude that analysis of the temporal alterations in the spectral components of the EMG and SAP signals in rats during mechanical ventilation provides a sensitive method of measuring fentanyl-induced muscular rigidity and the accompanying alterations in haemodynamic variables.     

The dependence of shifts in arterial pressure and cardiac output during alpha-adrenoreceptor stimulation on the initial (controlled) tonus of arterial vessels in rats

A significant decrease in arterial pressure and total peripheral resistance occurred following elevation of the initial blood pressure to 160 mm Hg with mesathone in anesthetised rats. The increase in the cardiac output remaining unchanged. Vascular and cardiac mechanisms of the revealed relationships are discussed.     

Some physical properties of the pulmonary arterial bed deduced from pulsatile arterial flow and pressure

Effects of varying olfactory cues on the behavior of domestic male mice (Mus musculus) towards territorial boundaries were studied. Territories were established by three pairs of males in a 154 X 86 X 10 cm Plexiglas pen with a moveable floor. After establishment of territories, the floor was shifted 19 cm a total of 21 times on different days. After 13 of these shifts the floor was subsequently covered with perforated sheet metal. In all 8 of the uncovered shifts, and in 8 of the 13 covered shifts, the mice behaved as though the boundary was moved in the predicted direction and distance. The results indicate that mice can use olfactory cues to recognize territorial boundaries.     

Doppler-derived pulmonary arterial systolic pressure in patients with known systemic arterial pressures

In the present study, we evaluated Doppler-derived systolic pulmonary artery pressure in 476 hypertensive patients. Clinical interpretation of systolic pulmonary arterial pressure should take into account age, body size, and systolic blood pressure values.     

A computer arterial pressure measuring device]

The paper describes a non-invasive oscillometric blood pressure (BP) measuring device. It provides an algorithm for the automatic measurement of systolic and diastolic BP values. A variant of assessing the BP measurement stability is proposed and the results of this assessment are given for 3 devices made by different firms. The total errors made by the studied device that functions as part of a physician's computer monitor are defined. Health institutions, resuscitation units, operating rooms for children and adults are an application sphere of the device.     

Systolic time intervals during isometric exercise in supine position should be corrected also for arterial pressure

In this paper we have studied the relationship between the systolic time intervals (STI) and the heart rate (HR) and systolic arterial pressure (SAP) in a group of 24 healthy subjects at three different effort levels during an isometric exercise in supine position and in basal conditions. We observed a decrease of the non corrected STI values during the exercise. Then we corrected STI using the regression equations obtained by plotting STI values versus the corresponding HR values at rest and during the exercise. We showed an increase of corrected left ventricular ejection time (LVET) during the whole exercise, and an increase of corrected total electromechanical systole (QS2c) at 50% effort level and then a return to the basal values. We also derived the multiple regression equations correlating QS2 and LVET with HR and SAP. Notwithstanding these equations show a significant positive correlation between the two STI considered and SAP only at the maximum effort, we corrected LVET and QS2 values by these equations assuming that the relationship between these parameters exists also in basal conditions and during the remaining stages of the exercise. By this correction we found a decrease of LVETc and QS2c in accordance with hemodynamic data reported by other authors. We may conclude that it seems useful to correct the STI obtained during isometric exercise in supine position both for HR and SAP.     

Changes in the arterial pressure after ligation of the hypogastric artery

The physiology of the pelvic territory after the ligation of the hypogastric arteries may be resumed in the following phenomena: the absence of bleeding, absence of ischemia and changes in pelvic vascular pattern. The hemostatic effect is noticed immediately after ligation, when the bleeding is considerably diminished, permitting to finish the surgical act. The blood pressure has been measured before ligation, immediately and it increases after five minutes due to the changes in local characteristic impedance. The impedance profile is in concordance with geometrical modification of the microvascular network made to prevent the ischemia. The increase in blood pressure five minutes after ligation is the result of the anastomosis between the ischiatic artery and other branches of the hypogastric artery, remaking the capillary bed in the pelvic territory.     

Changes in parameters of the systemic hemodynamics during combined action of humoral stimuli exerting various effects on arterial pressure

In anesthetised cats, i.v. administration of epinephrine (EP) in combination with acetylcholine (ACH) caused a decline of arterial pressure (AP), cardiac output (CO) and heart rate (HR) whereas stroke volume (SV) and total peripheral resistance (TPR) were increased. Combined administration of the HIS (histamine) and EP caused a decrease in only the AP and TPR, whereas CO, HR and SV were increased. The findings suggest that changes of systemic haemodynamics following combined i.v. administration of humoral stimuli depend on the mechanism of their action on the heart and vessels.     

Models of arterial pressure using a Windkessel type model: role of the functional arterial properties

The Windkessel model is a linear model which does not take into account the structural and functional variations of the arteries related to the pulsatility of the blood pressure (BP) and its variations between systole and diastole. OBJECTIVE: To analyse the performance of a BP modelisation where the parameters of AC are adjusted in a dynamic fashion according to a curvilinear relationship of the arterial properties (compliance) in relationship to the BP between systole and diastole. DESIGN AND METHODS: 9 control subjects (age 25 +/- 3). The non invasive measures of the radial BP waveform (Millar tonometry) was compared to that constructed by an electric simulator reproducing the model in a sysmetrical network subdivised into 121 segments where we introduced for each subject: at cardiac level, the aortic stroke volume (Doppler echocardiography), and at the radial level, the dynamic values of compliance and diameter according to an arc-tangent model (measured by arterial echography NiUS02). RESULTS: The BP obtained by the adjusted model, where the AC parameter follows the curvilinear, relationship dV/dP measured experimentally, was not significantly different from the experimental, while in the constant model (AC at mean BP level) the systolic BP was different. CONCLUSION: This work shows in an experimental way the limits inherent in simplification in the Windkessel modelisation of the vascular system with constant parameters. It shows in a conduction artery the influence of the functional properties of the arterial wall on the level of systolic and diastolic BP.     

Role of renal interstitial pressure on chronic control of arterial blood pressure

We examined the modulatory effect of serotonergic activities on haloperidol-induced up-regulation of dopamine D2 receptors in rat striatum. Chronic treatment with haloperidol (0.1, 0.5 mg/kg, i.p., 3 weeks) increased the number of dopamine D2 receptors, while no increase was observed with atypical antipsychotic drugs clozapine (10 mg/kg) and ORG 5222 (0.25 mg/kg). Chronic treatment with MK 212, a serotonin (5-HT)2A/2C receptor agonist (2.5 mg/kg), or with citalopram, a 5-HT reuptake inhibitor (10 mg/kg), potentiated the haloperidol (0.1 mg/kg)-induced up-regulation of dopamine D2 receptor, while that with (+/-)-8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), a 5-HT1A receptor agonist (0.1 mg/kg), had no influence on the dopamine D2 receptor up-regulation. Co-administration of ritanserin (1 mg/kg), a 5-HT2A/2C receptor antagonist, with a low dose of haloperidol (0.1 mg/kg), but not with a high dose of the agent (0.5 mg/kg), attenuated the dopamine D2 receptor up-regulation. Drug occupation of 5-HT2A and dopamine D2 receptors in vivo examined with use of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) was 69.8% and 45.1%, respectively, after the acute administration of haloperidol (0.1 mg/kg) plus ritanserin (1 mg/kg). This profile that 5-HT2A receptors were highly occupied compared with dopamine D2 receptors was similar to that of clozapine or ORG 5222. These results suggest that potent 5-HT2A receptor antagonism versus weak dopamine D2 receptor blockade may be involved in the absence of up-regulation of dopamine D2 receptors after chronic treatment with clozapine or ORG 5222.     

The correlations between the arterial and venous components of the hemodynamics and cerebrospinal fluid pressure in arterial hypotension

A total of 30 patients with arterial hypotension were examined. Rheoencephalogrammes documented hypotension of the arterial and venous constituents of the brain in one third of the above patients (in those patients with physiological hypotension it was recordable more frequently): in one forth of those cases with primary arterial hypotension presenting with the cerebral crises, moderately severe venous and arterial hypotension was generally seen. In a major proportion of the examinees, a correlation was found between the drop in arterial pressure, vascular tension of the arterial vessels of the brain and an adequate state of the venous tension and liquor pressure. Roentgenography of the skull and ophthalmoscopy do not permit forming an opinion about liquor hypertension since it was not demonstrated on the computerized tomographic scans.