Jean Claude Raphaël

BACKGROUND: Guillain-Barré syndrome is an acute symmetric usually ascending and usually paralysing illness due to inflammation of peripheral nerves. It is thought to be caused by autoimmune factors, such as antibodies. Plasma exchange removes antibodies and other potentially injurious factors from the blood stream. It involves connecting the patient's blood circulation to a machine which exchanges the plasma for a substitute solution, usually albumin. Several studies have evaluated plasma exchange for Guillain-Barré syndrome. OBJECTIVES: To systematically review the evidence concerning the efficacy of plasma exchange for treating Guillain-Barré syndrome. SEARCH STRATEGY: Search of the Cochrane Neuromuscular Disease Trial Register for randomised trials concerning plasma exchange in Guillain-Barré syndrome, search of the bibliographies of identified papers and enquiry from the authors of the papers. SELECTION CRITERIA: Randomised and quasi-randomised trials of plasma exchange versus sham exchange or supportive treatment. DATA COLLECTION AND ANALYSIS: Potentially relevant papers were scrutinised by two reviewers and the selection of eligible studies was agreed by them and a third reviewer. Data were extracted by one reviewer and checked by a second reviewer. Some missing data were obtained from the authors of studies. MAIN RESULTS: Six eligible trials concerning 649 patients were identified, all comparing plasma exchange versus supportive treatment alone. Primary outcome measures ~Bullet~Time to recover walking with aid In the only two trials for which this measure was reported the median time to recover this ability was faster in the plasma exchange than the control group. ~Bullet~Time to onset of motor recovery in mildly affected patients In the one trial for which this measure was available the time was significantly shortened in the plasma exchange group. Secondary outcome measures ~Bullet~Improvement in disability grade at 4 weeks In five trials, there were significantly more patients who had improved by one disability grade or more in the plasma exchange group as compared to the control group. Patients treated with plasma exchange fared significantly better in the following secondary outcome measures: time to recover walking without aid, percentage of patients requiring artificial ventilation, duration of ventilation, full muscle strength recovery after one year, and severe sequelae after one year. There were less patients with infectious events and cardiac arrhythmias in the plasma exchange than the control group. Subgroup analyses Plasma exchange was beneficial in patients with mild, moderate and severe (needing ventilation) Guillain-Barré syndrome. It was beneficial in patients with a disease duration of seven or less days and also in those with disease lasting more than seven days. However, in the only trial that enrolled patients up to 30 days from disease onset, the benefit of plasma exchange in patients treated after seven days was less apparent. Type of treatment Single studies showed that two plasma exchanges were significantly superior to none for mild Guillain-Barré syndrome and four to two for moderate Guillain-Barré syndrome but that six were not superior to four for severe Guillain-Barré syndrome requiring ventilation. One study suggested that continuous flow plasma exchange was significantly superior to intermittent flow. Another study found no significant difference between the two techniques. The same study found a significantly higher rate of adverse events with fresh frozen plasma as the replacement fluid than albumin. REVIEWER'S CONCLUSIONS: Plasma exchange is the first and only treatment that has been proven to be superior to supportive treatment alone in Guillain-Barré syndrome. Consequently, plasma exchange should be regarded as the treatment against which new treatments, such as intravenous immunoglobulin, should be judged. In mild Guillain-Barré syndrome two sessions of plasma exchange are superior to none. In moderate Guillain-Barré syndrome four sessions are superior to two. In severe Guillain-Barré syndrome six sessions are no better than four. Continuous flow plasma exchange machines may be superior to intermittent flow machines and albumin to fresh frozen plasma as the exchange fluid. Plasma exchange is more beneficial when started within seven days after disease onset rather than later, but was still beneficial in patients treated up to 30 days after disease onset. The value of plasma exchange in children less than 12 years old is not known.

OBJECTIVE: To assess the frequency of vasopressin deficiency in septic shock. DESIGN: Prospective cohort study. SETTING: Intensive care unit at Raymond Poincaré University Hospital. PATIENTS: A cohort of 44 patients who met the usual criteria for septic shock for < 7 days. A second cohort of 18 septic shock patients were enrolled within the first 8 hrs of disease onset. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: General demographics, severity scores, vital signs, standard biochemical data, and circulating vasopressin levels were systematically obtained at baseline in the two cohorts. Vasopressin deficiency was defined by a normal plasma vasopressin level in the presence of a systolic blood pressure of <100 mm Hg or in the presence of hypernatremia. Baroreflex sensitivity was systematically evaluated in patients of the first cohort when vasopressin deficiency was noted. In the second cohort of patients, plasma levels of vasopressin were obtained at baseline, 6, 24, 48, and 96 hrs after shock onset. In the first population, plasma vasopressin levels were inversely correlated to the delay from shock onset. Fourteen patients had relative vasopressin deficiency: 12 patients had systolic blood pressure <100 mm Hg, with impaired baroreflex sensitivity in four, and three patients had hypernatremia. In the second population, only two patients had relative vasopressin deficiency. The plasma levels of vasopressin significantly decreased over time (p < 10-3). CONCLUSIONS: Plasma vasopressin levels are almost always increased at the initial phase of septic shock and decrease afterward. Relative vasopressin deficiency is seen in approximately one-third of late septic shock patients.

The autonomic cardiovascular control was investigated in 10 patients with septic shock, 10 patients with sepsis syndrome, and six tilted healthy subjects. Overall variability, high- and low-frequency components (AUC, HF, and LF, beats/min(2)/Hz or mm Hg(2)/Hz) from heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressures spectra were obtained from 5-min recordings. LF(HR)/HF(HR) and the square root of LF(SBP)/LF(HR) (alpha) were used as indices of sympathovagal interaction and baroreflex control of the heart, respectively. Compared with tilted control subjects and patients with sepsis syndrome, septic shock is characterized by reduction in: (1) HR variability, i.e., decreased AUC(HR) (p = 0.007), LF(HR) (p = 0.002), and LF(HR)/HF(HR) (p = 0.0002); (2) DBP variability, i.e., decreased AUC(DBP) (p = 0.003) and LF(DBP) (p = 0.001), (3) alpha (p = 0.003). In septic shock, LF(HR)/HF(HR), alpha, and LF(DBP) correlated with mean blood pressure (r = 0.67, p = 0.04, r = 0.64, p = 0.03, and r = 0.88, p = 0.0008, respectively), and with plasma norepinephrine levels (r = -0.65, p = 0.03, r = -0.79, p = 0.006, and r = -0.69, p = 0.03, respectively). In conclusion, onset of septic shock is characterized by high concentrations of circulating catecholamines but impaired sympathetic modulation on heart and vessels, suggesting that central autonomic regulatory impairment contributes to circulatory failure.

OBJECTIVE: Continuous positive airway pressure (CPAP) is considered an effective nonpharmacologic method of treating patients with severe acute cardiogenic pulmonary edema. However, we hypothesized that bilevel noninvasive positive-pressure ventilation (NPPV), which combines both inspiratory pressure support and positive expiratory pressure, would unload the respiratory muscles and improve cardiac and hemodynamic function more effectively than CPAP. DESIGN: Randomized crossover study. SETTING: Critical care unit, Raymond Poincaré Hospital. PATIENTS: Six consecutive patients with acute cardiogenic pulmonary edema. INTERVENTIONS: Patients were sequentially treated with 5 cm H2O CPAP, 10 cm H2O CPAP, and NPPV in a random order. MEASUREMENTS AND MAIN RESULTS: Cardiac and hemodynamic function and indexes of respiratory mechanics were measured at each treatment sequence. NPPV reduced the esophageal pressure swing and esophageal pressure-time product compared with baseline (p <.05). There was no reduction in esophageal pressure swing or esophageal pressure-time product with CPAP. NPPV and 10 cm H2O CPAP reduced the mean transmural right and left atrial filling pressures without a change in cardiac index. CONCLUSIONS: This study demonstrates that NPPV was more effective at unloading the respiratory muscles than CPAP in acute cardiogenic pulmonary edema. In addition, NPPV and 10 cm H2O CPAP produced a reduction in right and left ventricular preload, which suggests an improvement in cardiac performance.