Biomedical subjects
Publications and source records attributed to R Proietti.
The authors review the main systems used in the clinical setting to condition inspiratory gases during mechanical ventilation. More in details, the functional principles of hot water humidifiers and heat and moisture exchangers are described.
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.
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.
Laparoscopic surgery requires a series of procedures, including intraperitoneal CO2 insufflation, which can cause cardiovascular and hemogasanalytic modifications, potentially able to impair cerebral perfusion. The aim of this study was to evaluate changes in cerebral blood flow velocity during laparoscopic cholecystectomy. Eighteen patients undergoing laparoscopic cholecystectomy were studied. Middle cerebral artery blood flow velocity was monitored using transcranial Doppler ultrasonography. Electrical bioimpedance was employed to measure cardiac output, stroke volume and to calculate derived parameters. End-tidal CO2, mean arterial blood pressure, end expiratory anesthetic concentration and O2 saturation were monitored non-invasively. Cerebral artery blood flow velocity increased significantly after CO2 insufflation (p < 0.05) and remained stable. The highest values were reached after CO2 desufflation. A significant reduction in stroke volume and cardiac output (p < 0.05) associated with increased vascular systemic resistances (p < 0.001) was observed soon after CO2 insufflation. The decrease in cardiac output and the increase in vascular systemic resistances remained significant throughout abdominal insufflation. Heart rate and mean arterial pressure remained substantially unchanged with the exception of a significant decrease (p < 0.001) before CO2 insufflation. There was no significant change in end-tidal CO2 during abdominal insufflation. These findings suggest that the cerebrovascular system can undergo adaptive changes during all phases of laparoscopic surgery. However, the extent of cardio- and cerebrovascular variation indicates the need for careful preliminary evaluation of cerebral hemodynamics in patients with vascular disorders before laparoscopic surgery.
BACKGROUND: It has been observed that the incidence and prevalence of candida infections in critically ill non-immunocompromised patients has increased. This study aims to evaluate the utility of the use of serological tests (double immunodiffusion and Cand-Tec Test) for the determination of candidemia. METHODS: A retrospective evaluation is made of 214 patients admitted to the Intensive Care Unit (ICU) of the Agostino Gemelli University Polyclinic during a period of 42 months. The double immunodiffusion technique was utilized for the determination of Candida antibodies. The Cand-Tec latex agglutination test was performed to evaluate the presence of Candida antigen. Four hundred and fifty-five antigen and antibody tests were performed. RESULTS: Thirty-six patients (16.8%) developed an invasive candidiasis. The sensitivity and specificity of antibody detection tests was 29 and 67 respectively; the positive predictive value was 15 and the negative predictive value was 82. The sensitivity and specificity of the antigen detection test ranged between 82 and 3 and between 8 and 98 respectively according to different cut-off titre; the positive predictive value was low (13-17%) and the negative predictive value decreased from 70 to 29. CONCLUSIONS: The utility of the use of serological tests in the diagnosis of candidemia is extremely limited. The gold standard for the determination of Candida sepsis remains the demonstration of candida in blood or in tissues.
BACKGROUND: Systems for Target Controlled Infusion accepting not only patient' data, like Diprifusor, but also a pharmacokinetic model have not been available in Italy in the last years. Therefore a program which controls a Pilot Anesthesia Vial pump and accepts any pharmacokinetic model was developed and applied to propofol infusion for anaesthesia and sedation. METHODS: Two versions of the Visual TCI program have been developed. The first, at intervals, supplies the anaesthetist with the values for the pump; the second directly interacts with the pump. The program also supplies the anaesthetist with the current amount of drug in each compartment and with the estimated awakening time. DESIGN: preliminary prospective study. SETTING: operatory theatre and Intensive Care Unit in a University Hospital. PATIENTS: 6 patients undergoing total intravenous anaesthesia with propofol and fentanyl for abdominal surgery; 6 patients undergoing sedation with propofol in an Intensive Care Unit (the first 4-hour period was taken into account). INTERVENTIONS: propofol infusion was regulated by the Visual TCI program. The first version was employed in three patients of each group and the second one in the others. Hypo- and hypertensive episodes (systolic pressure less than 80 mmHg or higher than basal value plus 25%) were recorded during anaesthesia and sedation. Propofol concentration was measured in plasma three times at defined intervals and per cent differences between measured and computer-calculated values (Predictive error, PE) were calculated. RESULTS: No hypo- or hypertensive episodes were recorded. PE was 27.4 +/- 17.9%. CONCLUSIONS: The program was easily employed, caused no inconvenience, and its use was associated with a remarkable cardiovascular stability. PE distribution was acceptable on the ground of the criteria reported in the literature. The program can be applied to drugs other than propofol, with both two and three compartment pharmacokinetic models and the anaesthetist can choose the most suitable model for the patient.
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Anaesthesia, surgical procedures and operating room temperature can deeply alter the human thermoregulatory system. Unexpected and sometimes serious perioperative complications can occur. Many studies have been carried out in order to describe and evaluate the detrimental effects produced by different anaesthesia procedures (whether by general, regional or integrated anaesthesia) on thermic homeostasis. More recently it has also been reported that perioperative hypothermia significantly affects patients' outcome, increasing intraoperative blood losses, incidence of postoperative wound infection, and hospital stay. Italian anaesthetists have still a poor consideration about intraoperative body temperature monitoring and patients' warming as basic important skills for a better anaesthesiologic patients management. According with the literature, we do believe that this is not a right opinion. The purpose of the present paper would be to point out the most important knowledges concerning thermic homeostasis management, in order to increase anaesthesiologist's awareness in this essential field of patients perioperative care.
To evaluate the efficacy of Multiple Choice Questions (MCQ) as an evaluation tool in medical education, were analyzed the responses to 80 MCQ delivered by 300 physicians working in emergency departments and following a course on Basic and Advanced Life Support. Pre- and post-test were administered using a dedicated computer application running on PC. Students' scores were high and demonstrated both course and test validity. More than 95% of the students used the computer application without interface difficulties. However, some limits of MCQ were individuated: first, misinterpretation of some questions, especially when two or more similar answers were presented; from the other side, the student's personal experiences during the course practice could influence student's responses bringing him to different conclusions on respect to the instructor. These difficulties should be kept in mind in the development of a MCQ session, and students should have the possibility to give to the instructor a feedback of problems encountered during the course. This is especially important when MCQ are the sole evaluation technique.
Here we report a clinical case concerning differential diagnosis between tetanus and metoclopramide intoxication. A 67 year old woman was admitted to our intensive care unit complaining of both trisma and four limbs hypertone soon after a massive metoclopramide bolus administration. The patient was affected by a chronicle renal insufficiency and a diagnosis of metoclopramide intoxication was made. The long lasting dystonic symptomatology together with respiratory insufficiency ruled out the hypothesis of drug overdose. The intensive care physicians would take into account that at least a 24 hours clinical observation is mandatory in order to perform a correct diagnosis.
Multimodality evoked potentials (EPs), linear electroencephalograms and Glasgow Coma Scale (GCS) scores were recorded within 24 h of cardiac arrest in 62 patients who were comatose following cardiopulmonary resuscitation. The cardiac arrest had a cardiac cause in 35 patients and a non-cardiac cause in 27 patients. The Glasgow Outcome Scale (GOS) scores were established 6 months after resuscitation. The prognostic value of all the recorded variables was calculated in terms of sensitivity, specificity and accuracy. Spearman's rank test was also used for the determination of the correlation coefficients with GOS. EP recordings furnished no falsely pessimistic predictions, with a specificity of 100%. In other words, when EPs were altered, the prognosis was always poor. However, while all patients who regained consciousness had normal EPs, not all patients in whom EPs were recordable survived. The GCS score showed a higher sensitivity and correlation with GOS score than EPs, but it was associated with a high percentage of false positive results, and its specificity was only 67%. The combination of the GCS score with EPs may be a promising strategy to counterbalance the respective limits of these methods and to reduce the loss of information due to sedation and myorelaxation, which impede clinical examination but not EP results.
AIM: To evaluate the auditive function of a group of critical patients after discharge from an ICU. DESIGN: An audiological screening was carried out 90-120 days after discharge. PATIENTS: Eighteen patients, that had been admitted to a polyvalent ICU for head injury, stroke or complicated neurosurgical procedures. They had all been in a coma. INTERVENTIONS: all the patients had undergone orotracheal intubation and mechanical ventilation lasting more than a week as well as ototoxic drugs (aminoglycosides and furosemide) administration. Antibiotic plasma levels had been monitored. MEASUREMENTS AND RESULTS: At examination, only 7 subjects were aware of being hypoacusic; no other symptom was reported. However audiometry and impedentiometry revealed the presence of mono or bilateral middle ear effusion in 11 subjects (61%) and high frequency neurosensorial hypoacusia in 2 cases (11%). Human voice frequencies were poorly affected by both transmissive and neurosensorial damages so that subjects did not report any hearing loss. CONCLUSIONS: Neurosensorial hypoacusia was probably caused by amynoglycoside toxicity in spite of blood level monitoring; ABR could be effective in preventing toxic damage by detecting early hearing impairment. Middle ear effusion occurrence is difficult to be prevented but appropriate medical therapy is usually effective after the recovery from coma.
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After some brief considerations on the history of the concept of suggestion, the authors evaluate the importance of this concept in the doctor-patient relationship in which the pharmacological variable is present. They report their personal experience through a case report and hope for an integrated approach in which the drug could be seen as a biological and relational agent.
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For a period of six months (april to october 1990) 361 manic-depressive in-patients or out-patients were examined and treated. 178 patients (119 females and 69 males) were suffering from depression at examination time. Among them, 34 women and 11 men had mixed mood disorders with a symptomatology near that of typical depression (major depression, according to the DSM III-R criteria) but not of mixed bipolar disorder. The main symptoms were: dysphoric mood with irritability; internal tension, psychic and sometimes physical agitation; emotional lability; head crowded with thoughouts or thoughts that vanish too quickly; sleep disorders with initial insomnia or with frequent night awakenings; suicidal thoughts or attempted suicide with impulsiveness. These patients sustained severe suffering. They were in no way slow-minded but rather talkative and expressive. Antidepressant drugs increased agitation and insomnia, and in some cases, suicidal impulses. BZDs had limited efficacy but neuroleptics given in small doses, anticonvulsants and lithium gave very effective results. A limited number of electroshocks provided rapid improvement. In many respects, depression with delirium seems a more severe form of the above-described combined depressive syndrome and responds to the same treatments. We think that this mood disorder includes excitement as an important component, although this was not clearly evident. However, it is not easy to conceive this syndrome as a mixture of depressive and manic symptoms; it should rather be regarded as another specific mood condition, either permanent or transient, situated between the two other conditions.
Eighty-six bilateral impedance audiometries were performed weekly in 35 unconscious ICU patients. Tympanometry showed the presence of middle-ear effusion in 43.3% of the examinations (80% of the patients). The incidence of effusion was significantly higher in patients older than 50 years, in intubated and mechanically ventilated patients and in the presence of microbial colonization of the upper airways. The acoustic reflex (AR) was characterized by increased threshold values in 23.8% of the examinations and was absent in 41.3%. Abnormal or absent ARs were usually associated with middle-ear effusion or tube malfunction.
OBJECTIVES: To assess the prognostic reliability of multimodality-evoked potentials and to evaluate the diagnostic implications and define the limits of these evoked potentials. SETTING: An ICU in a university hospital. DESIGN: Prospective clinical study. PATIENTS: Seventy-three severely head-injured patients aged 10 to 75 yrs. METHODS: Serial recording of brainstem auditory-evoked potentials and somatosensory-evoked potentials between days 1 and 21 after trauma. Comparison between evoked potential findings and prognosis, along with clinical data. RESULTS: Considering the single recordings of both brainstem auditory-evoked potentials and somatosensory-evoked potentials, the accuracy of prognostication in predicting a bad outcome was good only for severely abnormal brainstem auditory-evoked potentials. Serial brainstem auditory-evoked potential recordings and simultaneous recordings of brainstem auditory-evoked potentials and somatosensory-evoked potentials proved to be good prognostic indices in predicting a favorable outcome. Brainstem auditory-evoked potentials correlated well with brainstem reflexes and with pupil asymmetries but did not correlate with Glasgow Coma Scale scores. CONCLUSIONS: Serial recording and the use of a multimodality approach provided the best prognostic capabilities. The main diagnostic implications were: a) the possibility of detecting brainstem compression by means of brainstem auditory-evoked potentials before the appearance of pupil abnormalities; b) the usefulness of brainstem auditory-evoked potentials in monitoring brainstem function in patients undergoing high-dose barbiturate therapy. The main limitations of evoked potentials were the occurrence of peripheral acoustic damage, the electromagnetic sources of artifacts in the ICU, and the administration of ototoxic drugs.