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Biomedical subjects

M A Pennisi

Publications and source records attributed to M A Pennisi.

At least 19 recordsLinked to original sources
PubMed2005

Hypoalbuminaemia does not impair Diprifusor performance during sedation with propofol.

BACKGROUND: About 98% of plasma propofol is bound to albumin. We investigated if severe hypoalbuminaemia may affect the accuracy of a target-controlled infusion (TCI) device, the Diprifusor, during sedation in critically ill patients. METHODS: Ten critically ill hypoalbuminaemic patients (<24 g litre(-1)) and 10 critically ill normoalbuminaemic patients (>32 g litre(-1)) were included in this study. They underwent sedation with propofol, aimed at a Ramsey sedation score of 4-5. The Diprifusor was used to achieve target propofol plasma concentrations that ranged between 0.6 and 1.5 mg litre(-1). Propofol concentration was measured by high-performance liquid chromatography 5 min, 15 min, 30 min, 1 h, 2 h, 4 h, 6 h and 8 h after starting TCI. The accuracy of TCI was evaluated by calculating performance errors [PE=100x(measured concentration-predicted concentration)/predicted concentration], absolute and relative individual median performance errors (MDAPE and MDPE) and divergence (the slope of individual regression lines between PEs and time). RESULTS: PEs [median (range)] were -7 (-65, 79) in hypoalbuminaemic patients and -2 (-53, 188) in normoalbuminaemic patients; absolute PEs were 21 (1, 79) and 22 (0, 188). No significant difference was observed between the two groups. MDPE, MDAPE and divergence values were also similar. In most patients the accuracy of TCI increased with time because higher PE values were observed during the first 30 min. CONCLUSIONS: Hypoalbuminaemia does not affect the accuracy of Diprifusor during sedation with propofol in critically ill patients.

Adult↗
PubMed2003

Ketamine increases human motor cortex excitability to transcranial magnetic stimulation.

Subanaesthetic doses of the N-methyl-D-aspartate (NMDA) antagonist ketamine have been shown to determine a dual modulating effect on glutamatergic transmission in experimental animals, blocking NMDA receptor activity and enhancing non-NMDA transmission through an increase in the release of endogenous glutamate. Little is known about the effects of ketamine on the excitability of the human central nervous system. The effects of subanaesthetic, graded incremental doses of ketamine (0.01, 0.02 and 0.04 mg kg-1 min-1, I.V.) on the excitability of cortical networks of the human motor cortex were examined with a range of transcranial magnetic and electric stimulation protocols in seven normal subjects. Administration of ketamine at increasing doses produced a progressive reduction in the mean resting motor threshold (RMT) (F(3, 18) = 22.33, P < 0.001) and active motor threshold (AMT) (F(3, 18) = 12.17, P < 0.001). Before ketamine administration, mean RMT +/- S.D. was 49 +/- 3.3 % of maximum stimulator output and at the highest infusion level it was 42.6 +/- 2.6 % (P < 0.001). Before ketamine administration, AMT +/- S.D. was 38 +/- 3.3 % of maximum stimulator output and at the highest infusion level it was 33 +/- 4.4 % (P < 0.002). Ketamine also led to an increase in the amplitude of EMG responses evoked by magnetic stimulation at rest; this increase was a function of ketamine dosage (F(3, 18) = 5.29, P = 0.009). In contrast to responses evoked by magnetic stimulation, responses evoked by electric stimulation were not modified by ketamine. The differential effect of ketamine on responses evoked by magnetic and electric stimulation demonstrates that subanaesthetic doses of ketamine enhance the recruitment of excitatory cortical networks in motor cortex. Transcranial magnetic stimulation produces a high-frequency repetitive discharge of pyramidal neurones and for this reason probably depends mostly on short-lasting AMPA transmission. An increase in this transmission might facilitate the repetitive discharge of pyramidal cells after transcranial magnetic stimulation which, in turn, results in larger motor responses and lower thresholds. We suggest that the enhancement of human motor cortex excitability to transcranial magnetic stimulation is the effect of an increase in glutamatergic transmission at non-NMDA receptors similar to that described in experimental studies.

Adult↗
PubMed2003

New advances in the use of noninvasive ventilation for acute hypoxaemic respiratory failure.

Noninvasive ventilation (NIV) includes various techniques for augmenting alveolar ventilation without an endotracheal airway. The theoretical advantages of this approach include avoiding the complications associated with endotracheal intubation, improving patient comfort, preserving airway defence mechanisms, speech and swallowing. The successful application of NIV in hypoxaemic acute respiratory failure (ARF) of varied etiologies has been extensively described but success rate is strictly dependent on ARF etiology and until today the application of NIV strategies in the setting of hypoxaemic ARF is controversial. Larger, controlled studies are required to clarify the role of NIV in the setting of hypoxaemic ARF. The correct choice of the patient ventilator interface is a crucial issue in noninvasive ventilation. The study of new interfaces could improve tolerability reducing the noninvasive ventilation failure rate.

Acute Disease↗
PubMed2002

Effects of acid-base abnormalities on blood capacity of transporting CO(2): adverse effect of metabolic acidosis.

OBJECTIVE: To investigate the effects of some acid-base abnormalities on blood capacity of transporting CO(2). DESIGN: Prospective study. SETTING: General and Cardiosurgical ICUs of a University hospital. PATIENTS: Six groups of ten patients characterized by: metabolic alkalosis; respiratory alkalosis; absence of acid-base abnormalities; metabolic acidosis; uncompensated respiratory acidosis; and compensated respiratory acidosis. MEASUREMENTS AND RESULTS: The CO(2) dissociation curve, Haldane effect, and the ratio Ra-v between Ca-vCO(2) and Pa-vCO(2) were calculated from arterial and mixed-venous blood gas analyses. The CO(2) dissociation curve was shifted upwards by metabolic alkalosis and compensated respiratory acidosis and downwards by metabolic acidosis. The slope of the curve was unaffected, but CO(2) transport not due to Haldane effect was significantly lower in respiratory acidosis since the slope was less steep at higher PCO(2) values. In comparison with controls, patients affected by metabolic acidosis showed lower Haldane effect values (0.18+/-0.15 vs 0.59+/-0.26 ml of CO(2) per ml of arterial-mixed venous O(2) content difference; P <.05) and Ra-v values (0.43+/-0.10 vs 0.84+/-0.17 ml of CO(2) transported by 100 ml of blood per Torr of arterial-mixed venous PCO(2) gradient; P <.05). CONCLUSIONS: Our findings suggest that acid-base abnormalities, particularly metabolic acidosis, markedly affect blood capacity of transporting CO(2) and may worsen tissue hypercarbia associated with hypoperfusion. However, because of possible errors due to small measurements and the assumptions of the method, in the future definitive clarification will require the construction of original CO(2) dissociation curves for each acid-base abnormality.

Acidosis↗
PubMed2002

Role of desmopressin in the treatment of a case of septic shock refractory to catecholamines.

The authors describe a case of septic shock refractory to high-dose catecholamines after adequate volemic filling, rapidly corrected with the administration of desmopressin at a dose of 0.02 U/min. There are, in the literature, several cases of septic shock refractory to high-dose catecholamines successfully treated with arginine-vasopressin, a selective V1 agonist. This agent can potentially induce coronary vasoconstriction and presents a very difficult weaning, that imposes a slow reduction of the infusion amount. On the contrary, desmopressin does not present those adverse effects and is able to maintain a high renal blood flow, for its prevalent action on V2 instead of V1 receptors.

Aged↗
PubMed2001

Predictors of failure of noninvasive positive pressure ventilation in patients with acute hypoxemic respiratory failure: a multi-center study.

CONTEXT: In patients with hypoxemic acute respiratory failure (ARF), randomized studies have shown noninvasive positive pressure ventilation (NPPV) to be associated with lower rates of endotracheal intubation. In these patients, predictors of NPPV failure are not well characterized. OBJECTIVE: To investigate variables predictive of NPPV failure in patients with hypoxemic ARF. DESIGN: Prospective, multicenter cohort study. SETTING: Eight Intensive Care Units (ICU) in Europe and USA. PATIENTS: Of 5,847 patients admitted between October 1996 and December 1998, 2,770 met criteria for hypoxemic ARF. Of these, 2,416 were already intubated and 354 were eligible for the study. RESULTS: NPPV failed in 30% (108/354) of patients. The highest intubation rate was observed in patients with ARDS (51%) or community-acquired pneumonia (50%). The lowest intubation rate was observed in patients with cardiogenic pulmonary edema (10%) and pulmonary contusion (18%). Multivariate analysis identified age > 40 years (OR 1.72, 95% CI 0.92-3.23), a simplified acute physiologic score (SAPS II) > or = 35 (OR 1.81, 95% CI 1.07-3.06), the presence of ARDS or community-acquired pneumonia (OR 3.75, 95% CI 2.25-6.24), and a PaO2:FiO2 < or = 146 after 1 h of NPPV (OR 2.51, 95% CI 1.45-4.35) as factors independently associated with failure of NPPV. Patients requiring intubation had a longer duration of ICU stay ( P < 0.001), higher rates of ventilator-associated pneumonia and septic complications ( P < 0.001), and a higher ICU mortality ( P < 0.001). CONCLUSIONS: In hypoxemic ARF, NPPV can be successful in selected populations. When patients have a higher severity score, an older age, ARDS or pneumonia, or fail to improve after 1 h of treatment, the risk of failure is higher.

Acute Disease↗
PubMed2001

[Diagnostic imaging and patient database managing systems: The integration of digital information in the experience of an intensive care center].

AIM: To present our experience with integrating digital information on Intensive Care Unit patients (clinical data, laboratory findings, imaging, etc) to create electronic patient records. MATERIAL AND METHODS: Using the hospital Intranet, a connection was established between the Local area Network (LAN) of the Intensive Care Unit (ICU) and the Digital Imaging and Communications in Medicine (DICOM(R)) network of the Radiology Department allowing to receive, process and archive digital images locally at the ICU. Using the software RADclient-RADimage, the information received was managed by an electronic patient record system (DIGISTAT by UMS-Unterberger Medical Software, Florence). All the above software runs on Microsoft WindowsNT 4.0 platforms. RESULTS: Images of various kinds and formats (CT, MRI, etc.) pertaining to the ICU patients were semi-automatically handled and filed on a local server acting as a central databank. The images were then included in the electronic patient record and made available to the end user who could view them using either web technologies (hypertexts were automatically generated that could be viewed through the widely available World Wide Web browsers) or specific viewing utilities supplied with DIGISTAT . DISCUSSION AND CONCLUSIONS: For the intensivist, the handling and filing of data on hospitalised or discharged patients for treatment or research purposes involves having to process large amounts of information. Furthermore, in the event of patients being re-admitted to the unit, it is crucial to have ready access to all the information regarding previous hospital stays, including diagnostic images, to avoid the need for time-consuming searches through the hospital s paper-based archives. The possibility to access clinical information and diagnostic images using a single computer programme proved to be useful both for evaluating the patient s conditions immediately after the imaging procedure and for monitoring the patient s progress over time by comparing the different diagnostic images and imaging procedures. This pilot experience could be seen to provide the basic know-how for applying the method in the future Emergency Department of the A. Gemelli Hospital in Rome.

Computer Communication Networks↗
PubMed2000

Muscarinic receptor blockade has differential effects on the excitability of intracortical circuits in the human motor cortex.

The aim of the present study was to investigate whether muscarinic receptor blockade with scopolamine modifies the excitability of specific cortical networks of the human motor cortex as tested with transcranial magnetic stimulation. The effects of scopolamine on the excitability of human motor cortex were investigated in four healthy subjects using transcranial magnetic stimulation before and after an intravenous dose of scopolamine (0.006 mg/kg). We measured the threshold for motor responses, amplitude of motor responses, the duration of the cortical silent period, intracortical inhibition and facilitation, and short-latency inhibition produced by somatosensory input from the hand. In addition, we evaluated the amplitude of motor responses evoked by electrical anodal stimulation, since these responses originate from direct activation of corticospinal axons in the white matter and are not sensitive to changes in cortical excitability. Scopolamine decreased the threshold to magnetic stimuli and increased the amplitude of motor responses evoked by magnetic stimulation. In contrast, motor responses evoked by electrical stimulation were unaffected by administration of scopolamine. Scopolamine also led to a highly significant reduction in the amount of short-latency inhibition produced by somatosensory input from the hand. In contrast, short-latency intracortical inhibition and facilitation were not modified by scopolamine. The differential effect of scopolamine on motor responses evoked by magnetic and electrical stimulation of the motor cortex and the selective effect on somatosensory inhibition demonstrate that muscarinic blockade modifies the excitability of specific cortical networks in the human motor cortex.

Acetylcholine↗
PubMed2000

[Changes in acid-base equilibrium and CO2 output induced by bicarbonate infusion].

BACKGROUND: Bicarbonate therapy for metabolic acidosis can cause tissue hypercapnia. We tested the hypothesis that CO2 retention is initially confined to blood and that tissue hypercapnia is consequent to blood hypercapnia. METHODS DESIGN: prospective study. SETTING: general Intensive Care Unit in an University Hospital. PATIENTS: ten patients, aged 34-84, undergoing fixed mechanical ventilation for stroke, respiratory failure, polytrauma, or coma and presenting fairly stabilized circulatory condition were included in the study providing that definite exclusion criteria were absent. Sodium bicarbonate, 0.08, 0.17, and 0.25 mEq/kg, was infused in 5 minutes during stages A, B, and C. During each stage, before and after bicarbonate infusion, heart rate, arterial pressure, central venous pressure, and PetCO2 were registered and arterial and central venous haemogasanalysis were performed. CO2 output was measured during and after bicarbonate infusion and total CO2 output over basal values was calculated. RESULTS: Heart rate, arterial pressure, central venous pressure did not change in any stage, while PetCO2 increased in all. Following bicarbonate infusion, pH increased more in venous than in arterial blood and was significantly affected by the amount of bicarbonate infused. In arterial blood both PCO2 and total CO2 content (TCO2) increased. In venous blood PCO2 did not change while TCO2 increased so that arterial-venous rl CO2 difference was unaffected. CO2 output changed in no patient but two during stage A, and increased by 0.54 +/- 0.16 mL/kg during stage B and by 1.18 +/- 0.26 mL/kg during stage C so that 14.5 +/- 4.3 and 21.2 +/- 4.7% of given bicarbonate was released as CO2 through the lungs. CO2 output increased after a latency that was significantly shorter during stage C (145 +/- 51 sec) than during stage B (226 +/- 53 sec). CONCLUSIONS: Since arterial-venous TCO2 difference was unaffected and haemodynamic parameters were stable, the conclusion is drawn that CO2 and bicarbonate did not diffuse out of vascular compartment during this study. However CO2 and bicarbonate diffusion out of blood would have occurred if bicarbonate infusion had continued, because CO2 excess was released through the lungs after a latency and extended after the infusion. Consequently, tissue hypercapnia during bicarbonate infusion could probably be prevented by improving CO2 release through the lungs, i.e. by hyperventilating the patient.

Acid-Base Equilibrium↗
PubMed2000

[Non-invasive ventilation in intensive care. Update 2000].

NIV indications and application in critically ill patients have considerably expanded in the last few years: the aim of this paper is to shortly review NIV main indications, on the basis of data from the current scientific literature.

Critical Care↗
PubMed2000

[Home mechanical ventilation: the extra-hospital phase].

Home mechanical ventilation is the choice option, when there are no contraindications of medical or socio-economic order, in all cases of impossible complete weaning from ventilatory support. Easy to use, reliable and size limited positive pressure ventilators lead to a spread diffusion of this technique. In the patient/ventilator interface, tracheostomy is the golden choice for patient with great reduction in spontaneous ventilatory ability. For all other patients, perfectioning of non-invasive access (nasal and oral nasal mask) represent an effective progress. Major limitations in home ventilation are still, up to present, the lack of multidisciplinary structures able to give territorial assistance. Home ventilation therapy in the experience of the Policlinico Universtitario "La Sapienza", Rome is presented.

Home Care Services, Hospital-Based↗
PubMed1999

Cerebral blood flow and metabolic changes produced by repetitive magnetic brain stimulation.

We evaluated cerebral variation in oxyhemoglobin, deoxyhemoglobin, and cytochrome oxidase before and after transcranial magnetic and electrical stimulation in ten healthy volunteers using near-infrared spectroscopy. Immediately after magnetic but not after electric stimulation a significant increase in oxyhemoglobin and a decrease in cytochrome oxidase were observed (P < 0.05). Our data suggest that repetitive transcranial magnetic stimulation induces metabolic activation of the cerebral cortex together with an increase in cerebral blood flow.

Adult↗