Charlotte Arbelot

Bedside Ultrasound Assessment of Positive End Expiratory Pressure–induced Lung Recruitment

RATIONALE In the critically ill patients, lung ultrasound (LUS) is increasingly being used at the bedside for assessing alveolar-interstitial syndrome, lung consolidation, pneumonia, pneumothorax, and pleural effusion. It could be an easily repeatable noninvasive tool for assessing lung recruitment. OBJECTIVES Our goal was to compare the pressure-volume (PV) curve method with LUS for assessing positive end-expiratory pressure (PEEP)-induced lung recruitment in patients with acute respiratory distress syndrome/acute lung injury (ARDS/ALI). METHODS Thirty patients with ARDS and 10 patients with ALI were prospectively studied. PV curves and LUS were performed in PEEP 0 and PEEP 15 cm H₂O₂. PEEP-induced lung recruitment was measured using the PV curve method. MEASUREMENTS AND MAIN RESULTS Four LUS entities were defined: consolidation; multiple, irregularly spaced B lines; multiple coalescent B lines; and normal aeration. For each of the 12 lung regions examined, PEEP-induced ultrasound changes were measured, and an ultrasound reaeration score was calculated. A highly significant correlation was found between PEEP-induced lung recruitment measured by PV curves and ultrasound reaeration score (Rho = 0.88; P < 0.0001). An ultrasound reaeration score of +8 or higher was associated with a PEEP-induced lung recruitment greater than 600 ml. An ultrasound lung reaeration score of +4 or less was associated with a PEEP-induced lung recruitment ranging from 75 to 450 ml. A statistically significant correlation was found between LUS reaeration score and PEEP-induced increase in Pa(O₂) (Rho = 0.63; P < 0.05). CONCLUSIONS PEEP-induced lung recruitment can be adequately estimated with bedside LUS. Because LUS cannot assess PEEP-induced lung hyperinflation, it should not be the sole method for PEEP titration.

Ultrasound assessment of antibiotic-induced pulmonary reaeration in ventilator-associated pneumonia.

Objectives:To compare lung reaeration measured by bedside chest radiography, lung computed tomography, and lung ultrasound in patients with ventilator-associated pneumonia treated by antibiotics. Design:Computed tomography, chest radiography, and lung ultrasound were performed before (day 0) and 7 days following initiation of antibiotics. Setting:A 26-bed multidisciplinary intensive care unit in La Pitié-Salpêtrière hospital (University Paris–6). Patients:Thirty critically ill patients studied over the first 10 days of developing ventilator-associated pneumonia. Interventions:Antibiotic administration. Measurements and Main Results:Computed tomography reaeration was measured as the additional volume of gas present within both lungs following 7 days of antimicrobial therapy. Lung ultrasound of the entire chest wall was performed and four entities were defined: consolidation; multiple irregularly spaced B-lines; multiple abutting ultrasound lung “comets” issued from the pleural line or a small subpleural consolidation; normal aeration. For each of the 12 regions examined, ultrasound changes were measured between day 0 and 7 and a reaeration score was calculated. An ultrasound score >5 was associated with a computed tomography reaeration >400 mL and a successful antimicrobial therapy. An ultrasound score <–10 was associated with a loss of computed tomography aeration >400 mL and a failure of antibiotics. A highly significant correlation was found between computed tomography and ultrasound lung reaeration (Rho = 0.85, p < .0001). Chest radiography was inaccurate in predicting lung reaeration. Conclusions:Lung reaeration can be accurately estimated with bedside lung ultrasound in patients with ventilator-associated pneumonia treated by antibiotics. Lung ultrasound can also detect the failure of antibiotics to reaerate the lung.

Acute left ventricular dilatation and shock-induced myocardial dysfunction*

Objective:Whether cardiac ventricles can acutely dilate during septic myocardial dysfunction. Design:A prospective echocardiographic study was performed to assess changes of left ventricular dimensions over time in patients with septic shock. Settings:A 20-bed surgical intensive care unit of Pitié-Salpêtrière university hospital in Paris. Patients:Forty-five patients were studied over the first 10 days of septic shock. Interventions:None. Measurements and Main Results:Left ventricular end-diastolic area (LVEDA), fractional area change (FAC), velocity time integral of the aortic flow, echocardiographic indices of left ventricular relaxation, and cardiac troponin I (cTnI) were measured at day 1, 2, 3, 4, 7, and 10. Three groups were defined: 29 patients without increased cTnI and cardiac impairment (group 1), eight patients with increased cTnI and left systolic ventricular dysfunction (group 2), and eight patients with increased cTnI and isolated impairment of left ventricular relaxation (group 3). At day 1, LVEDA was significantly higher in group 2 (13 ± 3 cm/m2, p < 0.05) compared with groups 1 (10 ± 2 cm/m2) and 3 (11 ± 2 cm/m2). LVEDA did not change in groups 1 and 3. In group 2, LVEDA and FAC returned within 10 days to values observed in groups 1 and 2. A significant correlation was found between aortic velocity time integral and LVDEA (r =.78, p = 0.022) and FAC (r =.89, p = 0.003) only in group 2. Conclusions:Acute and reversible left ventricular dilation accompanies septic shock-induced systolic left ventricular dysfunction. When septic myocardial abnormalities are limited to reversible impairment of left ventricular relaxation, left ventricular dimensions remain unchanged.

Isolated and reversible impairment of ventricular relaxation in patients with septic shock.

Objective:Many patients with septic shock and increased cardiac troponin I (cTnI) do not exhibit significant left ventricular systolic dysfunction. We hypothesized that an isolated and reversible impairment of ventricular relaxation may be associated with the increase in cTnI. Design:Prospective, observational study. Setting:Surgical intensive care unit in a university hospital. Patients:Total of 54 patients with septic shock. Interventions:Fractional area change, early diastolic velocity of mitral annulus, flow propagation velocity of early diastolic mitral inflow, cTnI, tumor necrosis factor-&agr;, interleukin (IL)-6, -1&bgr;, -8, and -10 were measured at days 1, 2, 3, 4, 7, and 10 after onset of septic shock. Patients were classified into three groups: normal cTnI (group 1), increased cTnI and fractional area change <50% (group 2), and increased cTnI and fractional area change >50% (group 3). Measurements and Main Results:A total of 22 patients had an increase in cTnI, 11 with both systolic and diastolic dysfunctions and 11 with isolated impairment of left ventricular relaxation. At day 1, early diastolic velocity of mitral annulus and flow propagation velocity of early diastolic mitral inflow were significantly lower and tumor necrosis factor-&agr;, IL-8, and IL-10 significantly higher in groups 2 and 3 compared with group 1. With resolution of septic shock, early diastolic velocity of mitral annulus and flow propagation velocity of early diastolic mitral inflow measured in patients of groups 2 and 3 returned progressively to values observed in group 1, with a parallel normalization of tumor necrosis factor-&agr;, IL-8, and IL-10. Conclusions:Isolated and reversible impairment of left ventricular relaxation, associated with transient increases in cTnI, tumor necrosis factor-&agr;, IL-8, and IL-10, was observed in 20% of patients with septic shock.

Ultrasound assessment of lung aeration loss during a successful weaning trial predicts postextubation distress

Objective:Postextubation distress after a successful spontaneous breathing trial is associated with increased morbidity and mortality. Predicting postextubation distress is therefore a major issue in critically ill patients. To assess whether lung derecruitment during spontaneous breathing trial assessed by lung ultrasound is predictive of postextubation distress. Design and Setting:Prospective study in two multidisciplinary intensive care units within University Hospital. Patients and Methods:One hundred patients were included in the study. Lung ultrasound, echocardiography, and plasma B-type natriuretic peptide levels were determined before and at the end of a 60-min spontaneous breathing trial and 4 hrs after extubation. To quantify lung aeration, a lung ultrasound score was calculated. Patients were followed up to hospital discharge. Measurements and Main Results:Fourteen patients failed the spontaneous breathing trial, 86 were extubated, 57 were definitively weaned (group 1), and 29 suffered from postextubation distress (group 2). Loss of lung aeration during the successful spontaneous breathing trial was observed only in group 2 patients: lung ultrasound scores increased from 15 [13;17] to 19 [16; 21] (p < .01). End-spontaneous breathing trial lung ultrasound scores were significantly higher in group 2 than in group 1 patients: 19 [16;21] vs. 10 [7;13], respectively (p < .001) and predicted postextubation distress with an area under the receiver operating characteristic curve of 0.86. Although significantly higher in group 2, B-type natriuretic peptide and echocardiography cardiac filling pressures were not clinically helpful in predicting postextubation distress. Conclusion:Lung ultrasound determination of aeration changes during a successful spontaneous breathing trial may accurately predict postextubation distress.

Determinants of recovery from severe posterior reversible encephalopathy syndrome.

Objective Few outcome data are available about posterior reversible encephalopathy syndrome (PRES). We studied 90-day functional outcomes and their determinants in patients with severe PRES. Design 70 patients with severe PRES admitted to 24 ICUs in 2001–2010 were included in a retrospective cohort study. The main outcome measure was a Glasgow Outcome Scale (GOS) of 5 (good recovery) on day 90. Main Results Consciousness impairment was the most common clinical sign, occurring in 66 (94%) patients. Clinical seizures occurred in 57 (81%) patients. Median mean arterial pressure was 122 (105–143) mmHg on scene. Cerebral imaging abnormalities were bilateral (93%) and predominated in the parietal (93%) and occipital (86%) white matter. Median number of brain areas involved was 4 (3–5). Imaging abnormalities resolved in 43 (88%) patients. Ischaemic and/or haemorrhagic complications occurred in 7 (14%) patients. The most common causes were drug toxicity (44%) and hypertensive encephalopathy (41%). On day 90, 11 (16%) patients had died, 26 (37%) had marked functional impairments (GOS, 2 to 4), and 33 (56%) had a good recovery (GOS, 5). Factors independently associated with GOS<5 were highest glycaemia on day 1 (OR, 1.22; 95%CI, 1.02–1.45, p = 0.03) and time to causative-factor control (OR, 3.3; 95%CI, 1.04–10.46, p = 0.04), whereas GOS = 5 was associated with toxaemia of pregnancy (preeclampsia/eclampsia) (OR, 0.06; 95%CI, 0.01–0.38, p = 0.003). Conclusions By day 90 after admission for severe PRES, 44% of survivors had severe functional impairments. Highest glycaemia on day 1 and time to causative-factor control were strong early predictors of outcomes, suggesting areas for improvement.

Lung ultrasound in acute respiratory distress syndrome and acute lung injury.

Purpose of reviewLung ultrasound at the bedside can provide accurate information on lung status in critically ill patients with acute respiratory distress syndrome. Recent findingsLung ultrasound can replace bedside chest radiography and lung computed tomography for assessment of pleural effusion, pneumothorax, alveolar–interstitial syndrome, lung consolidation, pulmonary abscess and lung recruitment/de-recruitment. It can also accurately determine the type of lung morphology at the bedside (focal or diffuse aeration loss), and therefore it is useful for optimizing positive end-expiratory pressure. The learning curve is brief, so most intensive care physicians will be able to use it after a few weeks of training. SummaryLung ultrasound is noninvasive, easily repeatable and allows assessment of changes in lung aeration induced by the various therapies. It is among the most promising bedside techniques for monitoring patients with acute respiratory distress syndrome.

Aerosolized antibiotics for ventilator-associated pneumonia: lessons from experimental studies.

The aim of this review is to perform a critical analysis of experimental studies on aerosolized antibiotics and draw lessons for clinical use in patients with ventilator-associated pneumonia. Ultrasonic or vibrating plate nebulizers should be preferred to jet nebulizers. During the nebulization period, specific ventilator settings aimed at decreasing flow turbulence should be used, and discoordination with the ventilator should be avoided. The appropriate dose of aerosolized antibiotic can be determined as the intravenous dose plus extrapulmonary deposition. If these conditions are strictly respected, then high lung tissue deposition associated with rapid and efficient bacterial killing can be expected. For aerosolized aminoglycosides and cephalosporins, a decrease in systemic exposure leading to reduced toxicity is not proven by experimental studies. Aerosolized colistin, however, does not easily cross the alveolar–capillary membrane even in the presence of severe lung infection, and high doses can be delivered by nebulization without significant systemic exposure.

Ultrasound performs better than radiographs

We applaud the British Thoracic Society (BTS) for its efforts to improve patient care through scientific evidence. We thus recognise the recent guidelines on pleural procedures and thoracic ultrasound (TUS) as an important attempt to develop a rational approach to chest sonography.1 However, we are concerned that the BTS has reached conclusions based on a less complete review of TUS. The guidelines state that ‘the utility of thoracic ultrasound for diagnosing a pneumothorax is limited in hospital practice due to the ready availability of chest x-rays (CXR) and conflicting data from published reports’.1 This conclusion appears to be based on a small (but landmark) study of 11 patients from 1986 to 1989, two small studies with only four pneumothoraces in …

Severe and prolonged neurologic toxicity following subcutaneous chlorpyrifos self-administration: a case report.

Introduction. Organophosphate poisoning by oral or inhalation routes is characterized by a typical time-course of clinical features. Case presentation. We report a case of subcutaneous chlorpyrifos self-injection leading to a delayed cholinergic phase, prolonged coma, and severe permanent neurologic injury with electrophysiological patterns suggestive of overlapping intermediate syndrome and distal peripheral neuropathy. Time-course and severity of clinical features were not altered by either atropine or pralidoxime administration. Due to prolonged and severe alteration in consciousness, we used brain multimodal nuclear magnetic imaging and auditory cognitive event-related potentials to assess the patients potential for awakening. Electrophysiological testing used to monitor muscle weakness showed the coexistence of 20 Hz-decremental responses in proximal muscles and severe denervation in distal muscles. Red blood cell acetylcholinesterase activity progressively normalized on day 60, while plasma butyrylcholinesterase activity remained low until day 100. Chlorpyrifos was detectable in serum until day 30 and urine metabolites for up to three months, supporting the hypothesis of a continuous chlorpyrifos release despite repeated surgical debridement. We suggest that adipose and muscle tissues acted as a chlorpyrifos reservoir. At one-year follow-up, the patient exhibited significant neuromuscular sequelae. Conclusion. Subcutaneous chlorpyrifos self-injection may result in severe toxicity with prolonged neurologic injury, atypical overlapping electrophysiological patterns, and a poor final outcome.