Measurement of the quality factor of a new low-frequency differential accelerometer for testing the equivalence principle.

A cryogenic differential accelerometer has been developed to test the weak equivalence principle to a few parts in 10(15) within the framework of the general relativity accuracy test in an Einstein elevator experiment. The prototype sensor was designed to identify, address, and solve the major issues associated with various aspects of the experiment. This paper illustrates the measurements conducted on this prototype sensor to attain a high quality factor (Q ∼ 10(5)) at low frequencies (<20 Hz). Such a value is necessary for reducing the Brownian noise to match the target acceleration noise of 10(-14) g/√Hz, hence providing the desired experimental accuracy.

[Severe stroke: prognosis, intensive care admission and withhold and withdrawal treatment decisions]. / AVC graves : pronostic, critères d'admission en réanimation et décisions de limitations et arrêt de traitements.

INTRODUCTION: Stroke can produce irreversible brain damage of massive proportion leading to severe disability and poor quality of life. Resuscitation and mechanical ventilation of these patients remain controversial because of the high mortality and severe disability involved. STATE OF ART: When prognosis is very poor, do-not-resuscitate orders (DNR orders) and withhold or withdrawal of treatment may be discussed. Studies have shown that DNR orders are relatively frequent in acute stroke: up to 30% of all patients, and 50% of which are given upon admission. DNR orders are closely associated with severity of the neurological deficit and age. Precise estimates of withhold and withdrawal of treatment are not available, but terminal extubations in severe stroke could contribute to 40,000 to 60,000 acute stage deaths per year. Little is known about the decision making process and palliative care in these situations. The neurological prognosis is the main explicit criterion. However, evaluation of neurological outcome is highly uncertain and difficult, and does not always reflect quality of life. Several studies have raised the issue of this disability paradox. Thus, physician estimation of prognosis has a profound impact on decisions for life sustaining therapies, and may lead to self-fulfilling prophecies in case of false appreciation of published evidence. Other criteria could influence the withhold and withdrawal of treatment decision, such as social conditions and patient values. PERSPECTIVES AND CONCLUSION: Decisions for life-sustaining therapies in severe stroke are always difficult and often based on subjective and uncertain criteria. We have to improve prognosis estimation and our understanding of patient preferences to promote patient-centered care. An ethical approach may guide these complex decisions.

[Drug treatment of refractory status epilepticus]. / Traitement pharmacologique de l'état de mal réfractaire.

Status epilepticus (SE) refractory to benzodiazepines and other antiepileptic agents is managed with intravenous anesthetic compounds, such as thiopental, propofol or midazolam. These drugs display quite different pharmacodynamic and pharmacokinetic properties, but have not been prospectively compared to date. Their use is clearly advocated for the treatment of generalized convulsive SE, whereas partial-complex, or absence SE are generally managed less aggressively, in consideration of their better prognosis. The most important aspect seems to be related to the correct use of these anesthetics in the right context, rather than the choice of one specific compound. An electroencephalographic burst-suppression should be targeted for about 24 hour, before progressive weaning of the dosage under EEG monitoring. If this approach proves unsuccessful, the use of other drugs, including inhalational anesthetics, has been described.

[Causes of status epilepticus]. / Recherche étiologique lors d'un état de mal épileptique.

Because of the wide range of etiologies which may provoke status epilepticus (SE), physical examination, laboratory tests and neuroimaging must be conducted according to a well-designed hierarchical system. While implementing intensive care management, clinicians must of course search for curable causes but also consider the possible interaction of multiple factors and hidden diseases favoring or triggering SE. Causes of SE in idiopathic or cryptogenic epilepsy and new-onset SE do not correlate but careful analysis of serum chemistry and neuroimaging abnormalities must nevertheless be conducted with the specific objective of establishing an etiological diagnosis.

Mechanical ventilation in patients with acute ischemic stroke: survival and outcome at one year.

OBJECTIVE: To assess the prognosis of patients with acute ischemic stroke who require mechanical ventilation and to determine early factors influencing mortality. DESIGN: Prospective observational study. SETTING: Medical intensive care unit with a cerebrovascular emergency unit in a university-affiliated hospital. PATIENTS: Fifty-eight consecutive patients (mean age 65+/-13 years) requiring mechanical ventilation in the early course of an acute ischemic stroke. MEASUREMENTS AND RESULTS: Clinical data were recorded before intubation according to a standardized procedure. Mortality and functional outcome were assessed after a 1-year follow-up. Mechanical ventilation was started within 48 h after admission in 53 patients (91.4%). The mean duration of ventilation was similar in survivors (9.7+/-9.0 days) and non-survivors (8.6+/-8.7 days). Mortality was 72.4% at 1 year. Among the 16 survivors, none were in a persistent vegetative state and 11 had a Barthel index of 60, reflecting good functional status. Bilateral absence of corneal reflex and bilateral absence of pupillary light reflex had a positive predictive value of death of 1 (95% CI 0.78-1.00 and 0.74-1.00, respectively). After Cox regression analysis, presence of stupor or coma (OR 2.6, 95% CI 1.5-5.0), bilateral absence of corneal reflex before intubation (OR 3.4, 95% CI 1.4-8.7) and presence of ischemic cardiopathy (OR 2.8, 95% CI 1.4-5.5) were independent predictors of mortality. CONCLUSIONS: Systematic withholding of endotracheal intubation in patients with AIS is not recommended. Careful and rigorous neurologic examination, including assessment of brain stem reflexes, might help to identify patients with a very high probability of death despite mechanical ventilation.

Severe acute asthma with bowel infarction and pneumatosis intestinalis in a young adult.

A young patient presented with a small bowel infarction with pneumatosis intestinalis in the early course of life-threatening severe acute asthma. Low cardiac output with severe congestive right heart failure combined with the use of high doses of epinephrine to reverse the near-fatal bronchospasm probably contributed to this previously unreported complication. The presence of gas collections in the submucosal space was possibly the consequence of diffuse small bowel mucosal disruption. Early recognition of this unusual complication is of major importance to ensure appropriate therapeutic management.

"Colonization pressure" and risk of acquisition of methicillin-resistant Staphylococcus aureus in a medical intensive care unit.

OBJECTIVE: To determine the roles of "colonization pressure," work load or patient severity in patient acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in intensive care units (ICUs). DESIGN: Prospectively collected data from October 1996 through December 1998. SETTING: A 12-bed medical ICU in a university-affiliated general hospital. PATIENTS: Patients with risk factors for MRSA admitted to the ICU were screened within 72 hours of admission and weekly thereafter. MRSA was considered imported if detected during the first 72 hours of admission and nosocomial if detected only thereafter. Three screening strategies were used on admission during three consecutive periods. INTERVENTIONS: The unit of time chosen for measurements was the week. Weekly colonization pressure (WCP) was defined as the number of MRSA-carrier patient-days/total number of patient-days. Patient severity (number of deaths, Simplified Acute Physiologic Score [SAPS] II), work load (number of admis sions, Omega score), and colonization pressure (number of MRSA carriers at the time of admission, WCP) were compared with the number of MRSA-nosocomial cases during the following week. RESULTS: Of the 1,016 patients admitted over 116 weeks, 691 (68%) were screened. MRSA was imported in 91 (8.9%) admitted patients (13.1% of screened patients) and nosocomial in 46 (4.5%). The number of MRSA-nosocomial cases was correlated to the SAPS II (P=.007), the Omega 3 score (P=.007), the number of MRSA-imported cases (P=.01), WCP (P<.0001), and the screening period (P<.0001). In multivariate analysis, WCP was the only independent predictive factor for MRSA acquisition (P=.0002). Above 30% of WCP, the risk of acquisition of MRSA was approximately fivefold times higher (relative risk, 4.9; 95% confidence interval, 1.2-19.9; P<.0001). CONCLUSION: Acquisition of MRSA in ICU patients is strongly and independently influenced by colonization pressure.

[Severe forms of rubella encephalitis: arguments for a better vaccination policy]. / Formes sévères d'encéphalites au décours d'une infection rubéolique: arguments pour une meilleure couverture vaccinale.

BACKGROUND: Two cases of rubella encephalitis in young adults are reported. CASES REPORTS: 2 patients, 19 and 16-year-old, presented with severe encephalitis. One required mechanical ventilation. Neither were vaccinated against rubella. MRI scan of the brain was normal. The diagnosis was confirmed by serology. Good recovery was noted in both patients. DISCUSSION: Both cases of rubella encephalitis occurring in young adults illustrate the severity of this rare disease. As already shown in Finland, improvement with the French vaccination policy should lead to the prevention of rubella encephalitis.

Pulmonary function in sickle cell disease with or without acute chest syndrome.

Recurrent acute chest syndrome (ACS) has been suggested as a risk factor for chronic lung dysfunction in sickle cell disease. To investigate this hypothesis, lung function tests were performed in 49 sickle cell disease outpatients whose condition was stable, including 23 patients with a history of two to four episodes of ACS (ACS+) and 26 with no history of ACS (ACS-). The two groups were comparable regarding the sex ratio, body mass index, smoking history, physical characteristics, clinical history and usual lung function tests. Respiratory resistance (Rrs), measured using the forced oscillation technique, increased with the number of ACS episodes (r=0.55, p<0.0001) and a significant relationship was observed between Rrs as an independent variable and the expiratory flow rates at 25, 50 and 25-75% of the forced vital capacity as explanatory variables (r= 0.36, p<0.02; r=0.35, p<0.02; and r=0.4, p<0.006, respectively), with higher Rrs being associated with lower expiratory flow rates. The transfer factor (TL,CO) and transfer coefficient (KCO) for CO were significantly higher in the ACS+ group than in the ACS-group (TL,CO=84+/-4 versus 71+/-3%, p<0.004 and KCO=102+/-5 versus 90+/-3%, p<0.05, respectively). The data demonstrate that obstructive lung dysfunction is fairly common in sickle cell disease and suggest that recurrent acute chest syndrome may contribute specific obstructive defects. The increase in respiratory resistance associated with acute chest syndrome was accompanied by an increase in diffusion capacity, suggesting that it may have been related to an increase in lung blood volume.

[Enoximone in weaning from mechanical circulation support in pediatric patients]. / L'enoximone nello svezzamento da supporto meccanico di circolo in pazienti pediatrici.

OBJECTIVE: To assess and record the response to continuous infusion of the phosphodiesterase inhibitor enoximone during weaning from mechanical circulatory support (MCS) and to verify the possibility of success with this indication in pediatric patients. DESIGN: Retrospective study. SETTING: Pediatric cardiac surgery intensive care unit. PATIENTS: Two pediatric patients operated for complex congenital heart disease with low cardiac output syndrome in the immediate postoperative period, evolved in cardiocirculatory arrest despite massive inotropic pharmacological support, and then assisted by mechanical circulatory support. INTERVENTIONS: Weaning from mechanical circulatory support with continuous infusion of enoximone, only in one case preceded by a loading dose and associated with catecholamine infusion. MEASUREMENTS AND MAIN RESULTS: During weaning hemodynamic parameters (LAP, CVP, MAP, HR), SvO2, diuresis, rectal and cutaneous temperatures were assessed and recorded. A serial echocardiographic assessment of left ventricular systolic and diastolic diameters and ejection fraction (EF%) has also been performed every 12 hours. Weaning from MCS using enoximone as inotropic support was possible in both cases. CONCLUSIONS: Enoximone proved to be useful in weaning from MCS in two pediatric patients, despite the difficulty to assess its effect in one of the two cases in which enoximone was used together with high dosages of other inotropic drugs. These initial positive results urge us to further investigate applications of this drug in pediatric patients.

[Difficult intubation in paediatric cardiac surgery. Significance of age. Association with Down's syndrome]. / Intubazione difficile in cardiochirurgia pediatrica. Importanza dell'età. Relazione con la sindrome di Down.

OBJECTIVE: To assess the relationship between the age of pediatric patients and the likelihood of difficult intubations and to confirm the importance of Down Syndrome causing difficult intubations. DESIGN: Retrospective study. SETTING: Pediatric cardiac surgery operating room. PATIENTS: 627 pediatric patients, suffering from congenital heart disease, operated in our hospital from 1992 to 1994, divided in three age groups (under 1 month, between 1 month and 1 year, over 1 year of age). INTERVENTIONS: Translaryngeal intubation performed in the operating room before the operation. MEASUREMENTS: The percentage of difficult intubations was assessed in the three age groups and the association with Down syndrome was also considered. The likelihood of orotracheal intubations in each of the preceding groups was also examined. CONCLUSIONS: The percentage of difficult intubation in our experience was estimated to be 4.62%. Intubation's difficulty increases with decreasing age of non Down patients. The risk of difficult intubation in Down patients is, irrespectively of age, nearly 27% higher than in non-Downs (5.77% versus 4.52). However Down Syndrome seems to be important only in the age group between one month and one year. The percentage of orotracheal intubations in the preceding groups, even if indirectly, seem to confirm this observation.

Activation and inhibition of bovine carbonic anhydrase III by dianions.

We have found that many dianionic species, at millimolar concentrations, significantly activate or inhibit the bovine carbonic anhydrase III-catalyzed hydration of CO2. Dianionic species such as HPO2-4 and SO2-3, with pKb values near 7, are activators, whereas weakly basis species such as SO2-4 act as inhibitors. Both activation and inhibition are partial hyperbolic in nature and do not appear to compete with monoanionic linear inhibitors like N-3. Our kinetic data are consistent with a formal mechanism of action for carbonic anhydrase III that is directly analogous to that of carbonic anhydrase II, in which Lys-64 of carbonic anhydrase III can act as an intramolecular H+ transfer group during CO2 hydration. Our data suggest that dianionic inhibitors depress the rate of H+ transfer during turnover by stabilizing the protonated form of Lys-64. We postulate that dianionic activators enhance the rate of a rate-limiting H+ transfer step in the mechanism, probably by acting directly as H+ acceptors.

[L-tubocurarine and pancuronium bromide in open heart surgery]. / La d-tubocurarina e il bromuro di pancuronio in cardiochirurgia a cuore aperto

Comparison is made between 45 cases treated with d-tubocurarine and 60 with pancuronium bromide in open-heart surgery. Pancuronium displayed unmistakable advantages in the form of a more potent action, rapid commencement and long duration, dose flexibility and an almost complete absence of undesirable side-effects. In addition, it offered stability with respect to the cardiovascular system and enabled risk-free, deep muscle relaxation to be achieved even in subjects with complex cardiopathies, such as those with pulmonary hypertension, extreme hypoplasia or aplasia of the trunk of the pulmonary artery and patent ductus arteriosus, for whom a very high operative mortality risk exists when even minimal changes in cardiovascular parameters occur.