Jacques Leroy

Unplanned extubation: risk factors of development and predictive criteria for reintubation.

OBJECTIVES To define patients at risk for unplanned extubation; to assess the influence of nursing workload on the incidence of unplanned extubation; and to determine predictive criteria for patients requiring reintubation. DESIGN A prospective, case-control study, with 10 and 15 mos of data collection. SETTING University medical intensive care department. PATIENTS In the first study, which lasted 10 mos, unplanned extubation occurred in 40 (14%) of 281 ventilated and intubated patients; 36 cases were sufficiently documented to be compared with 74 intubated and ventilated controls. In the second study, which lasted 15 mos, the reintubated patients (n=23) of a series of 62 unplanned extubation patients were compared with those who were not reintubated (n=39). INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The following parameters were recorded: gender, age, main reason for admission, Simplified Acute Physiology Score II, route of intubation (oral or nasotracheal), tube diameter, ventilatory mode, FiO2, frequency and tidal volume delivered by the ventilator immediately before unplanned extubation, arterial blood gases performed 24 hrs before unplanned extubation, the presence of any sedation with, in this case, the last Ramsay score, the presence of hand restraints, the presence of weaning of ventilation, the accidental or deliberate nature of unplanned extubation, the Glasgow Coma Score at the time of unplanned extubation, the duration of ventilation before unplanned extubation, total duration of ventilation and stay in the intensive care unit, and the patients survival or death. The nursing workload was evaluated using a score derived from the Projet de Recherche en Nursing and adapted to intensive care. Unplanned extubation patients were more frequently intubated orally than controls (33.3% vs. 14.9%, respectively; p< .05). In the population of sedated patients, unplanned extubation patients were more frequently agitated than controls (60% vs. 19%, respectively; p < .05). The nursing workload did not differ between days with and days without unplanned extubation. Twenty-three (37%) of the 62 cases of documented unplanned extubation were reintubated. Predictive factors of reintubation are, in decreasing order of importance: Glasgow Coma Score of <11, accidental nature of unplanned extubation, and a PaO2/FiO2 ratio <200 torr (<26.7 kPa). CONCLUSIONS Patients at risk for unplanned extubation are characterized by oral intubation and insufficient sedation. In the department studied, and with the specific score used, we did not observe a relationship between the nursing workload and the incidence of unplanned extubation. A Glasgow Coma Score of <11, the accidental nature of unplanned extubation, and a PaO2/FiO2 ratio <200 torr (<26.7 kPa) are factors associated with a risk of reintubation.

Increased initial flow rate reduces inspiratory work of breathing during pressure support ventilation in patients with exacerbation of chronic obstructive pulmonary disease

ObjectiveTo investigate whether the level of initial flow rate alters the work of breathing in chronic obstructive pulmonary disease (COPD) patients ventilated in pressure support ventilation (PSV).DesignProspective study.SettingsMedical ICU in University hospital.PatientsEleven intubated COPD patients.MethodsWe modulated the initial flow rate in order to achieve seven different sequences. In each sequence, the plateau pressure was reached within a predetermined time: 0.1, 0.25, 0.50, 0.75, 1, 1.25 or 1.50 s. The more rapidly the pressure plateau was achieved, the higher was the initial flow rate. In each patient, the pressure support level was an invariable parameter. The order of the seven sequences for each patient was determined randomly.Measurements and resultsTen minutes after application of each initial flow rate, we measured the following parameters: inspiratory work of breathing, electromyogram (EMG) of the diaphragm (EMGdi), breathing pattern, and intrinsic positive end-expiratory pressure (PEEPi). Comparison between the means for each sequence and each variable measured was performed by two-way analysis of variance with internal comparisons between sequences by Duncans test. The reduction of the initial flow rate induced a progressive increase in the values of the work of breathing, EMGdi, and mouth occlusion pressure (P 0.1). In contrast, the reduction of the initial flow rate did not induce any significant change in tidal volume, respiratory frequency or PEEPi.ConclusionAs the objective of PSV is to reduce the work of breathing, it seems logical to use the highest initial flow rate to induce the lowest possible work of breathing in COPD ventilated patients.

Mechanical effects of airway humidification devices in difficult to wean patients.

ObjectiveTo evaluate the influence of airway humidification devices on the efficacy of ventilation in difficult to wean patients. DesignA prospective, randomized, controlled physiologic study. SettingA 22-bed medical intensive care unit in a university hospital. PatientsChronic respiratory failure patients. InterventionsPerformances of a heated humidifier and a heat and moisture exchanger were evaluated on diaphragmatic muscle activity, breathing pattern, gas exchange, and respiratory comfort during weaning from mechanical ventilation by using pressure support ventilation. Eleven patients with chronic respiratory failure were submitted to four pressure support ventilation sequences by using the heated humidifier and the heat and moisture exchanger at two different levels of pressure support ventilation (7 and 15 cm H2O). Measurement and Main ResultsCompared with the heated humidifier and regardless of the pressure support ventilation level used, the heat and moisture exchanger significantly increased all of the inspiratory effort variables (inspiratory work of breathing expressed in J/L and J/min, pressure time product, changes in esophageal pressure, and transdiaphragmatic pressure;p < .05) and dynamic intrinsic positive end-expiratory pressure (p < .05). Similarly, the heat and moisture exchanger produced a significant increase in Paco2 (p < .01) responsible for severe respiratory acidosis (p < .05), which was insufficiently compensated for despite a significant increase in minute ventilation (p < .05). This resulted in respiratory discomfort for all patients with the heat and moisture exchanger (p < .01). Adverse effects were partially counterbalanced by increasing the pressure support ventilation level with the heat and moisture exchanger by ≥8 cm H2O. ConclusionsThe type of airway humidification device used may negatively influence the mechanical efficacy of ventilation and, unless the pressure support ventilation level is considerably increased, the use of a heat and moisture exchanger should not be recommended in difficult or potentially difficult to wean patients with chronic respiratory failure.

Effects of pressure ramp slope values on the work of breathing during pressure support ventilation in restrictive patients.

OBJECTIVE To investigate, in restrictive patients, the influence of pressure ramp slope values on the efficacy of pressure support ventilation. DESIGN Prospective study. SETTING A university hospital medical intensive care unit. PATIENTS Twelve intubated restrictive patients. INTERVENTIONS Patients were randomly assigned to four sequences in which the values of the slope of the pressure ramp increase were modulated so that the plateau pressure was reached within a predetermined time: 0.1, 0.50, 1, or 1.50 secs. The more rapidly the pressure plateau was achieved, the higher was the initial flow rate. For convenience, these four different ventilatory settings were termed T 0.1, T 0.5, T 1, and T 1.5. MEASUREMENTS AND MAIN RESULTS We measured the following parameters 10 mins after application of each pressure ramp slope: inspiratory work of breathing, breathing pattern, and intrinsic PEEP (PEEPi). Work of breathing was evaluated using Campbells diagram, and expressed as a percentage of the values observed under spontaneous ventilation. A marked interindividual variation of the values for work of breathing was observed under spontaneous ventilation; the mean value for work of breathing was 1.97 +/- 0.82 joule/L, with a range of 1.22 to 4.10 joule/L. Comparison between the means for each sequence and each variable measured was performed by two-way analysis of variance with internal comparisons between sequences by Duncans test. Between the first (T 0.1) and the last (T 1.5) sequence, the reduction of values of the pressure ramp slope induced a progressive increase in the values for work of breathing, regardless of the mode of expression (in joule, joule/L, or joule/min). The values for work of breathing (joule/ L), expressed as a percentage of the values observed under spontaneous ventilation, increased from 44.2 +/- 14.4% to 78.3 +/- 17.8% (p < .001). In contrast, the reduction of the pressure ramp slope values and initial flow rate did not induce any significant change in tidal volume, respiratory frequency, and PEEPi. CONCLUSION Among the four tested slope values, the steepest was that which induced the lowest possible work of breathing in restrictive patients ventilated by pressure support ventilation. In this type of patient, we therefore suggest that the programmed pressure value should be reached by using a steep pressure ramp slope.

Noninvasive mechanical ventilation in clinical practice: A 2-year experience in a medical intensive care unit

ObjectiveTo evaluate the feasibility and outcome results of noninvasive mechanical ventilation (NIV) in daily clinical practice outside any prospective protocol-driven trial. DesignAn observational retrospective cohort study. SettingA 22-bed medical intensive care unit in a university hospital. PatientsA consecutive cohort of 124 patients who underwent 143 NIV trials, regardless of the indication, over two consecutive years (1997–1998). InterventionsNone. ResultsA total of 604 acute respiratory failure patients underwent mechanical ventilation, and 143 NIVs were performed in 124 patients. The overall prevalence of NIV use was 143 of 604 patients (24%) in three groups: hypoxemic acute respiratory failure (29.5%), hypercapnic acute respiratory failure (41%), and weaning/postextubation (29.5%). Intubation was avoided in 92 of 143 of the NIVs performed (64%), 19 (13%) after changing the initial NIV mode (i.e., a success rate of 62%, 51%, and 86% in the three groups, respectively). A total of 35 of 51 intubated patients (69%) required intubation during the first 24 hrs of NIV. Intensive care unit stay was 12 ± 10 days for the overall population, and mortality, when NIV failed, was 13 of 124 patients (10.5%). Arterial pH (p = .0527) and the Pao2/Fio2 ratio (p = .0482) after 1 hr were the only independent predictive factors for NIV failure by multivariate analysis. ConclusionsThis study confirms the results of controlled trials and demonstrates the feasibility and efficacy of NIV applied in daily clinical practice. These results suggest that NIV should be considered as a first-line ventilatory treatment in various etiologies of acute respiratory failure and as a promising weaning technique and postextubation ventilatory support. However, NIV should certainly be performed by a motivated and sufficiently trained care team.

Gastric mucosal acidosis and cytokine release in patients with septic shock.

ObjectiveIt has been postulated that in critically ill patients, splanchnic hypoperfusion may lead to cytokine release into the systemic circulation. The presence of cytokines could trigger an inflammatory response and cause multiple organ dysfunction syndrome. Although experimental studies support this hypothesis, humans studies remain controversial. The aim of the study was to determine the relationship between splanchnic hypoperfusion and cytokine release during septic shock. DesignHuman prospective study. SettingMedical intensive care unit at a university hospital. PatientsA total of 30 patients with mean arterial pressure of <60 mm Hg after volume loading with either oliguria or hyperlactatemia. MeasurementsGastric intramucosal measurements as an indicator of splanchnic hypoperfusion and blood samples were obtained at admission to the medical intensive care unit and repeated during 48 hrs. Cytokine (tumor necrosis factor-&agr; and interleukin-6) values were evaluated by enzyme-linked immunoassays at the following periods: at the time of admission and 2, 4, 8, 12, 24, 36, and 48 hrs later. Main ResultsHigh levels of interleukin-6 and tumor necrosis factor-&agr; were observed at admission in survivors and nonsurvivors, without significant difference. At 48 hrs, cytokine levels were significantly higher in patients who died compared with the survivors (tumor necrosis factor: 163 ± 16 for nonsurvivors vs. 34 ± 9 ng/mL for survivors; interleukin-6: 2814 ± 485 for nonsurvivors vs. 469 ± 107 ng/mL for survivors). At 48 hrs, the Pco2 gap was significantly higher in the nonsurvivors compared with survivors (25.87 ± 2.73 vs. 11.35 ± 2.25 mm Hg), despite systemic hemodynamic variables in the normal range. A positive relationship was demonstrated between plasma levels of tumor necrosis factor-&agr; and interleukin-6 and the Pco2 gap throughout the study. The Pco2 gap was not correlated with hemodynamic variables. ConclusionsOur data suggest a relationship between gastric mucosal acidosis, as assessed by Pco2 gap, and cytokine levels in critically ill patients with septic shock. Gut injury may be a contributor of the inflammatory response in patients with septic shock.

Acute pancreatitis after carbamate insecticide intoxication

A 29-year-old woman was admitted to the Rouen University Hospital for attempted suicide by ingestion of a carbamate insecticide (Temik G®, containing 10% aldicarb). Cardio-respiratory arrest occurred at the second hour and acute necrotic hemorrhagic pancreatitis on the second day. Further evolution was uneventful, and the patient was discharged after 43 days. Carbamate intoxication was confirmed by high urinary aldicarb metabolite concentrations. Pseudocholinesterase levels took 77 days to return to normal. Carbamate pesticides share the same pancreatic risk as organophosphorus pesticides, and should be monitored similarly.

Fomepizole (4-Methylpyrazole) in Fatal Methanol Poisoning with Early CT Scan Cerebral Lesions

BACKGROUND Methanol poisoning, potentially fatal, is generally treated with the combination of ethanol as antidote, and hemodialysis. Fomepizole, a competitive inhibitor of alcohol dehydrogenase, has more recently been used, and is capable of blocking the toxic metabolism of methanol. To our knowledge, its use has never been reported as an antidote in severe methanol poisoning requiring hemodialysis. CASE REPORT We report a case of fatal methanol poisoning (1.9 g/L on admission) suspected due to the combined presence of coma and severe metabolic acidosis with normokalaemia. CONCLUSION The fomepizole treatment protocol (10 mg/kg by i.v. infusion over 1 hour before dialysis, repeated 12 hours later in combination with 1.5 mg/kg/h during dialysis) was simple to use and appeared effective in eliminating methanol in combination with hemodialysis. The case is also unusual in terms of severity and the early onset of cerebral lesions demonstrated by computed tomography (CT) scan.

Syndrome of inappropriate secretion of antidiuretic hormone in two elderly women with elevated serum fluoxetine.

OBJECTIVE Fluoxetine is widely prescribed for depressed patients. Hyponatremia secondary to inappropriate secretion of antidiuretic hormone has been reported in a few cases associated with routine use of fluoxetine, especially in elderly patients. The mechanism has been postulated to be linked to the inappropriate secretion of antidiuretic hormone. Serum concentrations of antidiuretic hormone and fluoxetine have not been reported in previously published reports. CASE REPORT We report two new cases of severe and reversible hyponatremia associated with routine use of fluoxetine therapy in two elderly women. Fluoxetine-induced inappropriate secretion of antidiuretic hormone was confirmed by elevated serum concentrations of antidiuretic hormone and fluoxetine.

Group R streptococci: wild boars as a second reservoir.

Group R streptococci have caused many cases of septicaemia and meningitis in patients handling live or slaughtered pigs which were the only known reservoir of group R streptococci. A human case, due to a wild boar, is reported here and it is therefore concluded that there exist both a domestic (pig) and a wild (wild boar) reservoir of group R streptococci.