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Biomedical subjects

F Lemaire

Publications and source records attributed to F Lemaire.

At least 73 records · Page 4Linked to original sources
PubMed1997

Pressure-volume curves in acute respiratory failure: automated low flow inflation versus occlusion.

Pressure-volume (P-V) curves of the respiratory system allow determination of compliance and lower and upper inflection points (LIP and UIP, respectively). To minimize lung trauma in mechanical ventilation the tidal volume should be limited to the P-V range between LIP and UIP. An automated low flow inflation (ALFI) technique, using a computer-controlled Servo Ventilator 900C, was compared with a more conventional technique using a series of about 20 different inflated volumes (Pst-V curve). The pressure in the distal lung (Pdist) was calculated by subtraction of resistive pressure drop in connecting tubes and airways. Compliance (Cdist), Pdist(LIP), and Pdist(UIP) were derived from the Pdist-V curve and compared with Cst, Pst(LIP), and Pst(UIP) derived from the Pst-V curve. Nineteen sedated, paralyzed patients (10 with ARDS and 9 with ARF) were studied. We found: Cdist = 2.3 + 0.98 x Cst ml/cm H2O (r = 0.98); Pdist(LIP) = 0.013 + 1.09 x Pst(LIP) cm H2O (r = 0.96). In patients with ARDS: Pdist(UIP) = 4.71 + 0.84 x Pst(UIP) cm H2O (r = 0.94). In ARF, we found differences in UIP between the methods, but discrepancies occurred above tidal volumes and had little practical importance. They may reflect that Pdist comprises dynamic phenomena contributing to pressure in the distal lung at large volumes. Compliance, but not LIP and UIP, could be accurately determined without subtraction of resistive pressure from the pressure measured in the ventilator. We conclude that ALFI, which is fully automated and needing no ventilator disconnection, gives useful clinical information.

Acute Disease↗
PubMed1997

Lower respiratory tract colonization and infection during severe acute respiratory distress syndrome: incidence and diagnosis.

Ventilator-associated pneumonia (VAP) is difficult to detect and is often unsuspected during adult respiratory distress syndrome (ARDS). We prospectively evaluated lower respiratory tract (LRT) colonization and infection in 30 patients with severe ARDS (PaO2/FIO2 ratio < 150 mm Hg), using repeated quantitative cultures of plugged telescopic catheter (PTC) specimens taken blindly via the endotracheal tube every 48 to 72 h after onset of ARDS. All patients except one were receiving antibiotics. When VAP was suspected on the presence of clinical criteria for infection, a repeated PTC and, when possible, a bronchoalveolar lavage (BAL) were obtained before any new antimicrobials were administered; samples growing > or = 10(3) cfu/ml (PTC) or > or = 10(4) cfu/ml (BAL) were considered diagnostic of infection. Twenty-four VAP episodes were diagnosed in 18 patients (60% of patients or 4.2/100 ventilator-days) a mean of 9.8+/-5.7 d after onset of ARDS. Eighteen LRT colonization episodes were recorded; 16 of 24 (66%) VAP episodes were preceded (by 2 to 6 d) by LRT colonization with the same organism(s), and only two episodes of colonization were not followed by VAP. We conclude that although VAP is of relatively late-onset during severe ARDS, its incidence is much higher than in other conditions and can be underestimated. Lower airways colonization is consistently followed by infection with the same organisms and precedes VAP in two thirds of episodes. Repeated protected specimens taken blindly may provide a useful means to predict infection and therefore allow early antimicrobial therapy in high-risk patients with diffuse lung injury.

Acute Disease↗
PubMed1997

Trisomy 18 mosaicism in a mildly retarded boy with postnatal overgrowth.

We report a 6-year-old mildly retarded boy with trisomy 18 in 44% of peripheral lymphocytes. He had mild nonspecific dysmorphic features, microcephaly, micropenis with cryptorchidism and postnatal overgrowth. Trisomy 18 mosaicism was confirmed by a fluorescent in situ hybridization study. Ten previous reports of trisomy 18 mosaicism with normal or subnormal intelligence have been described but only one case of trisomy 18 mosaicism with high stature has been reported.

Child↗
PubMed1996

Aerosolized surfactant in adults with sepsis-induced acute respiratory distress syndrome. Exosurf Acute Respiratory Distress Syndrome Sepsis Study Group.

BACKGROUND: Patients with acute respiratory distress syndrome (ARDS) have a deficiency of surfactant. Surfactant replacement improves physiologic function in such patients, and preliminary data suggest that it may improve survival. METHODS: We conducted a prospective, multicenter, double-blind, randomized, placebo-controlled trial involving 725 patients with sepsis-induced ARDS. Patients were stratified according to the risk of death at base line (indicated by their score on the Acute Physiological and Chronic Health Evaluation [APACHE III] index) and randomly assigned to receive either continuously administered synthetic surfactant (13.5 mg of dipalmitoylphosphatidylcholine per milliliter, 364 patients) or placebo (o.45 percent saline; 361 patients) in aerosolized form for up to five days. RESULTS: The demographic and physiologic characteristics of the two treatment groups were similar at base line. The mean (+/- SD) age was 50 +/- 17 years in the surfactant group and 53 +/- 18 years in the placebo group, and the mean APACHE III scores at randomization were 70.4 +/- 25 and 70.5 +/- 25, respectively. Hemodynamic measures, measures of oxygenation, duration of mechanical ventilation, and length of stay in intensive care unit did not differ significantly in the two groups. Survival at 30 days was 60 percent for both groups. Survival was similar in the groups when analyzed according to APACHE III score, cause of death, time of onset and severity of ARDS, presence or absence of documented sepsis, underlying disease, whether or not there was a do-not-resuscitate order, and medical center. Increased secretions were significantly more frequent in the surfactant group; the rates of other complications were similar in the two groups. CONCLUSIONS: The continuous administration of aerosolized synthetic surfactant to patients with sepsis-induced ARDS had no significant effect on 30-day survival, length of stay in the intensive care unit, duration of mechanical ventilation, or physiologic function.

Administration, Inhalation↗
PubMed1996

Intrapleural administration of streptokinase in complicated purulent pleural effusion: a CT-guided strategy.

OBJECTIVE: To determine the usefulness and the results of a strategy using intrapleural streptokinase (SK) instillation guided by repeated computed tomography (CT) scan examinations in pleural empyemas unresponsive to chest tube drainage. DESIGN: A retrospective chart review. SETTING: The medical Intensive Care Unit and Department of Radiology, in a university hospital. PATIENTS: Sixteen patients with empyema who had a persistent pleural effusion despite drainage, among 37 patients with infectious pleural effusion. INTERVENTIONS: In the 16 patients, CT examination was performed before and at least once after SK. Intrapleural SK was instilled, either through the chest tube or via a needle puncture, according to the CT scan results. RESULTS: The first CT scan confirmed a persistent effusion in all, showing a multiloculated effusion in 13 patients, and an ectopic loculus in one. The first SK instillation resulted in a dramatic increase of fluid drained per day (from 68 +/- 28 ml to 567 +/- 262 ml; p < 0.001), leading to complete resolution in 11 patients, while the others required a second CT scan-guided procedure. In one, the chest tube was misplaced, while in two, transparietal injection was needed. Finally, a complete resolution was observed in 14 (87.5%) of the patients. Two patients had a poor initial response to SK and were eventually scheduled for video-thoracoscopy. A single episode of chills and fever was observed among 32 SK instillations. CONCLUSION: CT-guided SK instillation in pleural empyema appears to be safe, and allowed complete resolution in 87.5% of our patients.

Adult↗
PubMed1996

Making choices in hospital resources allocation. The use of an assessment tool to decide which new projects are financed.

We designed a scoring system to rank acute care hospital projects and allocate resources between them. The evaluation tool assessed projects on an ordinal scale; the criteria scored were medical interest, feasibility, interest for teaching and research, and compatibility with the hospital's strategy. Clinical and technical projects were ranked separately. In 1994, 25 new projects, representing a total cost of $1.4 million, were reviewed by two independent reviewers. The scores ranged from 30 to 18 over 36. Projects presented by clinical departments scored higher than projects presented by medicotechnical departments.

Budgets↗
PubMed1996

Gradual reduction of endotracheal tube diameter during mechanical ventilation via different humidification devices.

BACKGROUND: Limited data suggest that increased resistance to flow within endotracheal tubes (ETT) may occur in patients whose lungs are mechanically ventilated for more than 48 h, especially when airway humidification is inadequate. This could lead to sudden ETT obstruction or induce excessive loading during spontaneous breathing. METHODS: Twenty-three such patients were randomly assigned to three types of airway humidifier based on three different working principles: a Fisher Paykell hot water system (n = 7), a Pall BB2215 heat and moisture exchanger (HME) hydrophobic filter (n = 8), and a Dar Hygrobac 35254111 HME hygroscopic filter (n = 8). The decrease in internal pressure along the ETT and the flow rate were measured in each patient every 2 days. An "effective inner diameter" was derived from these measurements and allowed the inner ETT configuration to be monitored. RESULTS: On the first day of intubation, the mean diameter was similar in the three groups, and was slightly smaller than the in vitro diameter (mean +/- SD: 7.6 +/- 0.6 mm for Fisher-Paykell, 7.7 +/- 0.4 for Pall, and 7.5 +/- 0.4 for Dar). The mean diameter tended to decrease from day to day. At the end of the study, the overall reduction in mean diameter was significantly greater with the hydrophobic HME (Pall) than with the two other systems (Pall: -6.5 +/- 4% vs. 2.5 +/- 2.5% for Dar and 1.5 +/- 3% for Fisher-Paykell; P < 0.01 with analysis of variance). The same was true of the mean reduction in effective inner ETT diameter expressed per day of ventilation (-1.6 +/- 1.5% per day for Pall vs. -0.5 +/- 0.4% for Dar and -0.2 +/- 0.4% for Fisher-Paykell; P < 0.01). In four patients, the ETT became obstructed and emergency repeated tracheal intubation was required. The Pall HME and the Fisher-Paykell system were being used in three and one patient, respectively. Before obstruction, the reduction in ETT diameter was significantly greater for these four patients than for the remaining 23 patients (7.8 +/- 1.4% vs. 3.1 +/- 4.1%; P < 0.01). CONCLUSIONS: During prolonged mechanical ventilation, significant alterations in inner ETT configuration occur frequently and are influenced by the type of humidification device used. In vivo monitoring of ETT mechanical properties might be clinically useful.

Aged↗
PubMed1996

Parental origin and mechanisms of formation of three cases of 12p tetrasomy.

Pallister-Killian syndrome is a clinically recognizable syndrome characterized by tissue-limited mosaicism for an extra 12p isochromosome. Very little is known about the underlying mechanism of this rare rearrangement. Microsatellite markers were studied from three fetuses with Pallister-Killian syndrome and their parents to determine the parent of origin and the cell division yielding the additional isochromosome. In two cases the isochromosome contained the same allele(s) as a normal transmitted chromosome 12, one paternal and one maternal in origin. A third case showed inheritance of two different maternal alleles, indicating that at least one meiotic error was involved in the ultimate formation of the extra isochromosome.

Abnormalities, Multiple↗
PubMed1996

Effects of assisted ventilation on the work of breathing: volume-controlled versus pressure-controlled ventilation.

During assisted ventilation, the same tidal volume can be delivered in different ways, with the possibility for the physician to vary the ventilatory target (pressure or volume) and the peak flow setting. We compared the effects on the respiratory work rate of assisted ventilation, delivered either with a square wave flow pattern (assist control ventilation [ACV]) or with a decelerating flow pattern and a constant pressure (assisted pressure-control ventilation [APCV]). In the first part of the study where seven patients were studied, inspiratory time and tidal volume were similar in the two modes of ventilation. High and moderate levels of tidal volume (VT) were studied (12 ml/kg and 8 ml/kg, respectively). To obtain moderate VT, inspiratory time was kept constant and, therefore, mean inspiratory flow was reduced. At high VT, no difference between ACV and APCV was noted for breathing pattern, respiratory drive indexes, respiratory muscle work, or arterial blood gases. All patients exhibited respiratory alkalosis. At moderate VT, normal pH was achieved. In this situation significantly lower levels were observed during APCV than during ACV for the power of breathing (10 +/- 2 versus 19 +/- 5 J/min, p<0.05), transdiaphragmatic pressure swing (7 +/- 1 versus 11 +/- 2 cm H2O, p<0.05), and pressure-time index (252 +/- 43 versus 484 +/- 114 cm H2O.s, p<0.05), even though breathing pattern and gas exchange were similar. In the second part of the study where six additional patients were studied, tidal volume was kept constant at a moderate level (8 ml/kg), and we studied the effect of shortening inspiratory time and increasing mean inspiratory flow. At moderate VT and high inspiratory flow, no significant differences could be found between ACV and APCV, and although pressure-time index tended to be lower during APCV, absolute levels of effort were of small magnitude (56 +/- 55 versus 76 +/- 55 cm H2O.s). We conclude that at moderate VT and low flow rates only, inspiratory assistance delivered at a constant pressure reduces the respiratory work rate more effectively than assist control ventilation.

Aged↗
PubMed1996

Evaluation of a knowledge-based system providing ventilatory management and decision for extubation.

We evaluated whether a knowledge-based system (KBS) connected to a ventilator in pressure support mode could correctly predict the ability of patients to tolerate total withdrawal from ventilatory support. The KBS was designed to continuously adapt ventilatory assistance to the needs of the patient, to manage a strategy of gradually decreasing ventilatory assistance, and to indicate when the patient was able to breathe without assistance. Thirty-eight patients for whom weaning was being considered were evaluated using a conventional battery of parameters, including weaning criteria, tolerance of a T-piece trial, and outcome 48h after permanent withdrawal of ventilation. The results of this evaluation were compared with the suggestions made by the KBS at the end of a period of KBS-driven mechanical ventilation inserted in the conventional weaning procedure. The positive predictive value of the KBS was 89%, versus 77% for the conventional procedure and 81% for the rapid shallow breathing index alone. The KBS correctly predicted the course of five patients who tolerated a T-piece trial but required ventilation within 48 h. We conclude that our KBS ensured appropriate patient management during the weaning period and improved our ability to predict responses to weaning.

Adult↗
PubMed1996

Estimation of occlusion pressure during assisted ventilation in patients with intrinsic PEEP.

We conducted a study to assess the validity of the occlusion pressure (P0.1) measured during activation of the trigger mechanism (P0.1(aw)trig) in patients showing variable levels of PEEPi during pressure-support ventilation. We first compared P0.1(aw)trig and P0.1 measured with the conventional method (i.e., the airway pressure drop after the first 100 ms of an occluded inspiration) in 16 patients with chronic obstructive pulmonary disease (COPD). We observed good agreement and a highly significant correlation (r = 0.99; bias = 0.3 +/- 0.5 cm H20) between the two methods. In a second part of the study, we compared, in 17 patients, P0.1(aw)trig with (P0.1(es)), measured as the depression generated on the esophageal pressure tracing in the first 100 ms of the inspiratory negative swing, and with P0.1 measured on the P(es) tracing simultaneously with P(aw)trig (P0.1(es-synchro)). Our results showed a good correlation and good agreement between P(aw)trig and P0.1(es) (r = 0.92; bias = 0.3 +/- 0.5 cm H20); P(aw)trig and P0.1(es-synchro) (r = 0.97; bias = 0.1 +/- 0.2 cm H20); and P0.1(es) and P0.1(es-synchro) (r = 0.95, bias = 0.2 +/- 0.4 cm H20), respectively. This study suggests that reliable measurements of inspiratory drive can be obtained easily, on a breath-by-breath basis, from airway pressure tracings during pressure-support ventilation in patients with variable levels of PEEPi.

Airway Resistance↗
PubMed1996

Respiratory mechanics in patients ventilated for critical lung disease.

Respiratory mechanics, using flow interruption, was previously studied during the complete breath in healthy ventilated man, numerical techniques relieving constraints regarding flow pattern. The classical linear model of non-Newtonian behaviour was found to be valid. The present study was extended to subjects with critical lung disease. Subjects with acute lung injury (ALI; n = 2), acute respiratory distress syndrome (ARDS; n = 4), and chronic obstructive pulmonary disease (COPD; n = 3) were studied with and without positive end-expiratory pressure (PEEP). Functional residual capacity (FRC) was measured with sulphur hexafluoride (SF6) wash-out. The static pressure-volume (P-V) curve was linear at zero end-expiratory pressure (ZEEP), but nonlinear at PEEP. Its hysteresis was nonsignificant. In ALI/ARDS, PEEP increased lung volume by distension and recruitment, but only by distension in COPD. In ALI/ARDS, resistance was increased, at ZEEP. In COPD, resistance became extremely high during expiration at ZEEP. In ALI/ARDS at ZEEP, non-Newtonian behaviour, representing tissue stress relaxation and pendel-luft, complied with the classical linear model. At PEEP, the non-Newtonian compliance became volume-dependent to an extent correlated to the nonlinearity of the static P-V curve. In COPD, non-Newtonian behaviour was adequately explained only with a model with different inspiratory and expiratory behaviour. The classical model of the respiratory system is valid in ALI/ARDS at ZEEP. More advanced models are needed at PEEP and in COPD.

Adult↗
PubMed1996

[Mechanical circulatory assistance using the Novacor implanted device. A postoperative follow-up].

The postoperative follow-up of 8 patients on the waiting list for cardiac transplantation, with implanted left ventricular assist devices of the Novacor type, was marked by right ventricular failure in the first week, controlled by positive inotropic agents and the maintenance of high right ventricular preload. The outcome later on showed that an ambulatory life was possible for 6 of the 8 patients, allowing the wait for cardiac transplantation under excellent conditions. Three major complications were observed: a case of aspergillosis endocarditis, one vertebrobasilar cerebrovascular accident and one low output state by progressive degradation of right ventricular function: after a period of circulatory assistance of 52 to 201 days. 6 out of the 8 patients underwent cardiac transplantation, 5 of which were successful.

Adolescent↗
PubMed1995

Noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease.

BACKGROUND: In patients with acute exacerbations of chronic obstructive pulmonary disease, noninvasive ventilation may be used in an attempt to avoid endotracheal intubation and complications associated with mechanical ventilation. METHODS: We conducted a prospective, randomized study comparing noninvasive pressure-support ventilation delivered through a face mask with standard treatment in patients admitted to five intensive care units over a 15-month period. RESULTS: A total of 85 patients were recruited from a larger group of 275 patients with chronic obstructive pulmonary disease admitted to the intensive care units in the same period. A total of 42 were randomly assigned to standard therapy and 43 to noninvasive ventilation. The two groups had similar clinical characteristics on admission to the hospital. The use of noninvasive ventilation significantly reduced the need for endotracheal intubation (which was dictated by objective criteria): 11 of 43 patients (26 percent) in the noninvasive-ventilation group were intubated, as compared with 31 of 42 (74 percent) in the standard-treatment group (P < 0.001). In addition, the frequency of complications was significantly lower in the noninvasive-ventilation group (16 percent vs. 48 percent, P = 0.001), and the mean (+/- SD) hospital stay was significantly shorter for patients receiving noninvasive ventilation (23 +/- 17 days vs. 35 +/- 33 days, P = 0.005). The in-hospital mortality rate was also significantly reduced with noninvasive ventilation (4 of 43 patients, or 9 percent, in the noninvasive-ventilation group died in the hospital, as compared with 12 of 42, or 29 percent, in the standard-treatment group; P = 0.02). CONCLUSIONS: In selected patients with acute exacerbations of chronic obstructive pulmonary disease, noninvasive ventilation can reduce the need for endotracheal intubation, the length of the hospital stay, and the in-hospital mortality rate.

Acute Disease↗
PubMed1995

Comparison of the effects of pressure support ventilation delivered by three different ventilators during weaning from mechanical ventilation.

OBJECTIVE: To compare the effects of pressure support ventilation (PSV) delivered at the same level by three different ventilators on patients' work of breathing (WOB), breathing pattern and gas exchange. DESIGN: Prospective, self-controlled clinical study. SETTING: Intensive care unit of a tertiary university hospital. PATIENTS: Nine intubated adult patients during weaning from mechanical ventilation. INTERVENTIONS: Patients were randomly connected to one of three ventilators: the Siemens Servo 900 C (SC), the Ohmeda CPU 1 (CPU), and the Engström Erica (EE) during both zero cmH2O PSV and 15 cmH2O PSV. MEASUREMENTS AND RESULTS: During zero PSV, there was no significant difference in terms of WOB, VT, VE, or auto-PEEP among the three ventilators, although there was a trend towards higher levels of WOB with EE. During 15 cmH2O PSV, WOB was significantly less with SC than with EE or CPU (0.47 +/- 0.48 J/l for SC, 1.0 +/- 0.48 for EE and 0.78 +/- 0.51 for CPU1, p = 0.003). WOB was 64% less than at zero PSV with SC but only 38% less with EE. This was associated with a different pressurization shape, as assessed by the interior surface of Paw-VT loops (1.23 +/- 0.09 J/l for SC, 0.9 +/- 0.02 for EE, and 0.79 +/- 0.18 for CPU; p < 0.001). At 15 cmH2O PSV, auto-PEEP was significantly lower with SC than with EE (1.7 +/- 2.1 cmH2O for SC, 4.7 +/- 3.6 for EE, and 2.8 +/- 0.3 for CPU; p = 0.04). External expiratory resistances, in cmH2O/l/s, were significantly higher with EE than with CPU or SC (12.9 +/- 3.2 EE, 7.5 +/- 2.4 CPU, 5.9 +/- 0.5 SC; p < 0.001). CONCLUSION: During PSV, the different working principles of different mechanical ventilators profoundly affect patient's WOB. Among the various factors, velocity of pressurization of PSV may play a role in its efficacy in unloading the respiratory muscles.

Acute Disease↗