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Usefulness of parasternal intercostal muscle ultrasound during weaning from mechanical ventilationSupplemental Digital ContentMETHODSStudy B Decision to initiate pressure-support ventilation. Study C- Readiness criteria to undergo a first spontaneous breathing trial - Contraindications to magnetic stimulation of the phrenic nerves- Criteria defining failure of the spontaneous breathing trial- Measurement: the phrenic nerve stimulation methodRESULTSTable SDC1. Intra-class correlation – intra-observer variations of parasternal intercostal muscle ultrasound measurements in healthy subjects (study A) and patients (study C)Table SDC2. Comparison of ROC curves of the four indices to predict spontaneous breathing trial failureFigure SDC1. Changes in diaphragm thickening fraction (TFdi) and parasternal intercostal thickening fraction (TFic) under stepwise increase in pressure support (study B)* as compared to pressure support (PS) 7 and positive end expiratory pressure zero (ZEEP) for TFdi# as compared to pressure support (PS) 7 and positive end expiratory pressure zero (ZEEP) for TFicFigure SDC2. Receiver operating characteristics curves of endotracheal pressure induced by a bilateral phrenic nerve stimulation (Ptr,stim), diaphragm thickening fraction (TFdi), parasternal intercostal muscle thickening fraction (TFic) and TFic/TFdi ratio to predict failure of the spontaneous breathing trial.METHODSStudy B Decision to initiate pressure-support ventilation. Patients were considered ready to be placed on pressure-support ventilation if they could sustain this mode for at least 1 hour with: ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"1nV8qcyX","properties":{"formattedCitation":"\\super 1\\nosupersub{}","plainCitation":"1","noteIndex":0},"citationItems":[{"id":5379,"uris":[""],"uri":[""],"itemData":{"id":5379,"type":"article-journal","title":"Ultrasound evaluation of diaphragm function in mechanically ventilated patients: comparison to phrenic stimulation and prognostic implications","container-title":"Thorax","page":"811-818","volume":"72","issue":"9","source":"PubMed","abstract":"RATIONALE: In intensive care unit (ICU) patients, diaphragm dysfunction is associated with adverse clinical outcomes. Ultrasound measurements of diaphragm thickness, excursion (EXdi) and thickening fraction (TFdi) are putative estimators of diaphragm function, but have never been compared with phrenic nerve stimulation. Our aim was to describe the relationship between these variables and diaphragm function evaluated using the change in endotracheal pressure after phrenic nerve stimulation (Ptr,stim), and to compare their prognostic value.\nMETHODS: Between November 2014 and June 2015, Ptr,stim and ultrasound variables were measured in mechanically ventilated patients <24?hours after intubation ('initiation of mechanical ventilation (MV)', under assist-control ventilation, ACV) and at the time of switch to pressure support ventilation ('switch to PSV'), and compared using Spearman's correlation and receiver operating characteristic curve analysis. Diaphragm dysfunction was defined as Ptr,stim <11?cm?H2O.\nRESULTS: 112 patients were included. At initiation of MV, Ptr,stim was not correlated to diaphragm thickness (p=0.28), EXdi (p=0.66) or TFdi (p=0.80). At switch to PSV, TFdi and EXdi were respectively very strongly and moderately correlated to Ptr,stim, (r=0.87, p<0.001 and 0.45, p=0.001), but diaphragm thickness was not (p=0.45). A TFdi <29% could reliably identify diaphragm dysfunction (sensitivity and specificity of 85% and 88%), but diaphragm thickness and EXdi could not. This value was associated with increased duration of ICU stay and MV, and mortality.\nCONCLUSIONS: Under ACV, diaphragm thickness, EXdi and TFdi were uncorrelated to Ptr,stim. Under PSV, TFdi was strongly correlated to diaphragm strength and both were predictors of remaining length of MV and ICU and hospital death.","DOI":"10.1136/thoraxjnl-2016-209459","ISSN":"1468-3296","note":"PMID: 28360224","title-short":"Ultrasound evaluation of diaphragm function in mechanically ventilated patients","journalAbbreviation":"Thorax","language":"eng","author":[{"family":"Dubé","given":"Bruno-Pierre"},{"family":"Dres","given":"Martin"},{"family":"Mayaux","given":"Julien"},{"family":"Demiri","given":"Suela"},{"family":"Similowski","given":"Thomas"},{"family":"Demoule","given":"Alexandre"}],"issued":{"date-parts":[["2017",9]]}}}],"schema":""} 1 pressure support ≤24 cmH2O positive end-expiratory pressure ≤12 cmH2O total level of inspiratory pressure <30 cmH2O respiratory rate ≤24/min tidal volume ≥5 ml/kg ideal body weight, without signs of labored breathing, as defined by retractions or recessions - sucking in of the skin around the ribs and the top of the sternum, or prominent use of accessory respiratory muscles. Study CReadiness criteria to undergo a first spontaneous breathing trial The criteria used to assess the readiness for weaning were derived from the International Conference on Weaning: ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"VfGY9p7o","properties":{"formattedCitation":"\\super 2\\nosupersub{}","plainCitation":"2","noteIndex":0},"citationItems":[{"id":635,"uris":[""],"uri":[""],"itemData":{"id":635,"type":"article-journal","title":"Weaning from mechanical ventilation","container-title":"The European respiratory journal: official journal of the European Society for Clinical Respiratory Physiology","page":"1033-1056","volume":"29","issue":"5","source":"NCBI PubMed","abstract":"Weaning covers the entire process of liberating the patient from mechanical support and from the endotracheal tube. Many controversial questions remain concerning the best methods for conducting this process. An International Consensus Conference was held in April 2005 to provide recommendations regarding the management of this process. An 11-member international jury answered five pre-defined questions. 1) What is known about the epidemiology of weaning problems? 2) What is the pathophysiology of weaning failure? 3) What is the usual process of initial weaning from the ventilator? 4) Is there a role for different ventilator modes in more difficult weaning? 5) How should patients with prolonged weaning failure be managed? The main recommendations were as follows. 1) Patients should be categorised into three groups based on the difficulty and duration of the weaning process. 2) Weaning should be considered as early as possible. 3) A spontaneous breathing trial is the major diagnostic test to determine whether patients can be successfully extubated. 4) The initial trial should last 30 min and consist of either T-tube breathing or low levels of pressure support. 5) Pressure support or assist-control ventilation modes should be favoured in patients failing an initial trial/trials. 6) Noninvasive ventilation techniques should be considered in selected patients to shorten the duration of intubation but should not be routinely used as a tool for extubation failure.","DOI":"10.1183/09031936.00010206","ISSN":"0903-1936","note":"PMID: 17470624","journalAbbreviation":"Eur. Respir. J.","author":[{"family":"Boles","given":"J-M"},{"family":"Bion","given":"J"},{"family":"Connors","given":"A"},{"family":"Herridge","given":"M"},{"family":"Marsh","given":"B"},{"family":"Melot","given":"C"},{"family":"Pearl","given":"R"},{"family":"Silverman","given":"H"},{"family":"Stanchina","given":"M"},{"family":"Vieillard-Baron","given":"A"},{"family":"Welte","given":"T"}],"issued":{"date-parts":[["2007",5]]}}}],"schema":""} 2 adequate oxygenation (SpO2 90% on a fraction of inspired oxygen 40% and positive end expiratory pressure 8 cmH2O) respiratory rate 35/min a cooperative cognitive state stable cardiovascular status (systolic arterial blood pressure of 90-160 mmHg without or minimal vasopressors and heart rate 140/min)Contraindications to magnetic stimulation of the phrenic nervescardiac pacemaker or defibrillator cervical implantscervical spine injury pregnancy Non-inclusion criteria for study Csuspicion of underlying hemi-diaphragm paralysis (defined as an elevation of >2.5 cm of one hemi-diaphragm compared to the other on chest radiograph), pre-existing neuromuscular disorders, age <18 years and decision to withhold life-sustaining treatment. Criteria defining failure of the spontaneous breathing trialThe criteria of failure of the spontaneous breathing trial were derived from the International Conference on Weaning. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"EVqEpAGN","properties":{"formattedCitation":"\\super 2\\nosupersub{}","plainCitation":"2","noteIndex":0},"citationItems":[{"id":635,"uris":[""],"uri":[""],"itemData":{"id":635,"type":"article-journal","title":"Weaning from mechanical ventilation","container-title":"The European respiratory journal: official journal of the European Society for Clinical Respiratory Physiology","page":"1033-1056","volume":"29","issue":"5","source":"NCBI PubMed","abstract":"Weaning covers the entire process of liberating the patient from mechanical support and from the endotracheal tube. Many controversial questions remain concerning the best methods for conducting this process. An International Consensus Conference was held in April 2005 to provide recommendations regarding the management of this process. An 11-member international jury answered five pre-defined questions. 1) What is known about the epidemiology of weaning problems? 2) What is the pathophysiology of weaning failure? 3) What is the usual process of initial weaning from the ventilator? 4) Is there a role for different ventilator modes in more difficult weaning? 5) How should patients with prolonged weaning failure be managed? The main recommendations were as follows. 1) Patients should be categorised into three groups based on the difficulty and duration of the weaning process. 2) Weaning should be considered as early as possible. 3) A spontaneous breathing trial is the major diagnostic test to determine whether patients can be successfully extubated. 4) The initial trial should last 30 min and consist of either T-tube breathing or low levels of pressure support. 5) Pressure support or assist-control ventilation modes should be favoured in patients failing an initial trial/trials. 6) Noninvasive ventilation techniques should be considered in selected patients to shorten the duration of intubation but should not be routinely used as a tool for extubation failure.","DOI":"10.1183/09031936.00010206","ISSN":"0903-1936","note":"PMID: 17470624","journalAbbreviation":"Eur. Respir. J.","author":[{"family":"Boles","given":"J-M"},{"family":"Bion","given":"J"},{"family":"Connors","given":"A"},{"family":"Herridge","given":"M"},{"family":"Marsh","given":"B"},{"family":"Melot","given":"C"},{"family":"Pearl","given":"R"},{"family":"Silverman","given":"H"},{"family":"Stanchina","given":"M"},{"family":"Vieillard-Baron","given":"A"},{"family":"Welte","given":"T"}],"issued":{"date-parts":[["2007",5]]}}}],"schema":""} 2 The spontaneous breathing trial was considered to be a failure if at least one the following criteria was present:blood oxygen saturation (SpO2) of < 90 % with a fraction of inspired oxygen (FiO2) ≥ 50 %; acute respiratory distress (RR ≥ 40/min, agitation, cyanosis); systolic arterial blood pressure of ≥ 180 mmHg; cardiac arrhythmias; respiratory acidosis [pH7.32 with an arterial carbon dioxide tension (PaCO2) of ≥50 mmHg]. If none of these failure criteria was present, the spontaneous breathing trial was considered as successfully completed.MeasurementsParasternal intercostal muscle ultrasound. Patients and subjects were studied in a semi-recumbent position. A 10-15 MHz linear array transducer (Sparq ultrasound system, Phillips, Philips Healthcare, Andover, MA, USA for patients and HFL-38xe, FUJIFILM Sonosite, Bothell, WA, USA for healthy subjects) was positioned perpendicular to the anterior thorax surface in the sagittal plane, at the level of the second right intercostal space, approximately 6-8 cm lateral to the sternal edge with a window visualising the 2nd and 3rd ribs. This intercostal space was chosen as the inspiratory effect of the external parasternal intercostal muscle is maximal at this location, compared to more caudal interspaces. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"f99b4EjJ","properties":{"formattedCitation":"\\super 3\\nosupersub{}","plainCitation":"3","noteIndex":0},"citationItems":[{"id":904,"uris":[""],"uri":[""],"itemData":{"id":904,"type":"article-journal","title":"Respiratory action of the intercostal muscles","container-title":"Physiological reviews","page":"717-756","volume":"85","issue":"2","source":"NCBI PubMed","abstract":"The mechanical advantages of the external and internal intercostals depend partly on the orientation of the muscle but mostly on interspace number and the position of the muscle within each interspace. Thus the external intercostals in the dorsal portion of the rostral interspaces have a large inspiratory mechanical advantage, but this advantage decreases ventrally and caudally such that in the ventral portion of the caudal interspaces, it is reversed into an expiratory mechanical advantage. The internal interosseous intercostals in the caudal interspaces also have a large expiratory mechanical advantage, but this advantage decreases cranially and, for the upper interspaces, ventrally as well. The intercartilaginous portion of the internal intercostals (the so-called parasternal intercostals), therefore, has an inspiratory mechanical advantage, whereas the triangularis sterni has a large expiratory mechanical advantage. These rostrocaudal gradients result from the nonuniform coupling between rib displacement and lung expansion, and the dorsoventral gradients result from the three-dimensional configuration of the rib cage. Such topographic differences in mechanical advantage imply that the functions of the muscles during breathing are largely determined by the topographic distributions of neural drive. The distributions of inspiratory and expiratory activity among the muscles are strikingly similar to the distributions of inspiratory and expiratory mechanical advantages, respectively. As a result, the external intercostals and the parasternal intercostals have an inspiratory function during breathing, whereas the internal interosseous intercostals and the triangularis sterni have an expiratory function.","DOI":"10.1152/physrev.00007.2004","ISSN":"0031-9333","note":"PMID: 15788709","journalAbbreviation":"Physiol. Rev.","language":"eng","author":[{"family":"De Troyer","given":"André"},{"family":"Kirkwood","given":"Peter A"},{"family":"Wilson","given":"Theodore A"}],"issued":{"date-parts":[["2005",4]]}}}],"schema":""} 3 The second right parasternal intercostal muscle was identified as a three-layered biconcave structure: two linear hyperechoic membranes respectively running from the anterior and posterior aspects of the adjoining ribs, and a medial portion with muscle echotexture (Figure 1). Considering that during inspiration the muscle fibers of the parasternal intercostal contract, displacing the rib cage cranially and anteriorly ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"EVHNE8so","properties":{"formattedCitation":"\\super 3\\nosupersub{}","plainCitation":"3","noteIndex":0},"citationItems":[{"id":904,"uris":[""],"uri":[""],"itemData":{"id":904,"type":"article-journal","title":"Respiratory action of the intercostal muscles","container-title":"Physiological reviews","page":"717-756","volume":"85","issue":"2","source":"NCBI PubMed","abstract":"The mechanical advantages of the external and internal intercostals depend partly on the orientation of the muscle but mostly on interspace number and the position of the muscle within each interspace. Thus the external intercostals in the dorsal portion of the rostral interspaces have a large inspiratory mechanical advantage, but this advantage decreases ventrally and caudally such that in the ventral portion of the caudal interspaces, it is reversed into an expiratory mechanical advantage. The internal interosseous intercostals in the caudal interspaces also have a large expiratory mechanical advantage, but this advantage decreases cranially and, for the upper interspaces, ventrally as well. The intercartilaginous portion of the internal intercostals (the so-called parasternal intercostals), therefore, has an inspiratory mechanical advantage, whereas the triangularis sterni has a large expiratory mechanical advantage. These rostrocaudal gradients result from the nonuniform coupling between rib displacement and lung expansion, and the dorsoventral gradients result from the three-dimensional configuration of the rib cage. Such topographic differences in mechanical advantage imply that the functions of the muscles during breathing are largely determined by the topographic distributions of neural drive. The distributions of inspiratory and expiratory activity among the muscles are strikingly similar to the distributions of inspiratory and expiratory mechanical advantages, respectively. As a result, the external intercostals and the parasternal intercostals have an inspiratory function during breathing, whereas the internal interosseous intercostals and the triangularis sterni have an expiratory function.","DOI":"10.1152/physrev.00007.2004","ISSN":"0031-9333","note":"PMID: 15788709","journalAbbreviation":"Physiol. Rev.","language":"eng","author":[{"family":"De Troyer","given":"André"},{"family":"Kirkwood","given":"Peter A"},{"family":"Wilson","given":"Theodore A"}],"issued":{"date-parts":[["2005",4]]}}}],"schema":""} 3 and that their mass remains constant, an increase in thickness of the muscular structure can be visualized using ultrasound. Using M-mode, the ultrasound beam was perpendicularly directed at the midsection of the muscle, where it is the thinnest at end-expiration. The thickness of the parasternal intercostal muscle was measured on frozen images at end-expiration (Tee) and at peak inspiration (Tei). TFic was defined as the percent change in muscle thickness between expiration and inspiration. This change in thickness determined the thickening fraction of the parasternal intercostal muscle (TFic = (Tei - Tee)/Tee). All measurements were repeated on at least three separate breaths and their average was reported. For the sack of feasibility, ultrasound was performed on the right parasternal intercostal muscle only. Ultrasound measurements were performed by MD, BPD and SV.Phrenic nerve stimulation methodDiaphragm pressure generating capacity was assessed in terms of changes in endotracheal tube pressure induced by bilateral phrenic nerve stimulation during airway occlusion (Ptr,stim). Phrenic nerve stimulation was performed by bilateral anterior magnetic stimulation. In brief, two figure-of-eight coils connected to a pair of Magstim? 200 stimulators (The Magstim Company, Dyfed, UK) were positioned immediately posterior to the sternomastoid muscles at the level of the cricoid cartilage. Stimulations were delivered at the maximum output intensity of the stimulator (100%) that is known to consistently result in supramaximal phrenic contraction. ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"vFdjaDQS","properties":{"formattedCitation":"\\super 4\\uc0\\u8211{}7\\nosupersub{}","plainCitation":"4–7","noteIndex":0},"citationItems":[{"id":5381,"uris":[""],"uri":[""],"itemData":{"id":5381,"type":"article-journal","title":"Diaphragm dysfunction on admission to the intensive care unit. Prevalence, risk factors, and prognostic impact-a prospective study","container-title":"American Journal of Respiratory and Critical Care Medicine","page":"213-219","volume":"188","issue":"2","source":"PubMed","abstract":"RATIONALE: Diaphragmatic insults occurring during intensive care unit (ICU) stays have become the focus of intense research. However, diaphragmatic abnormalities at the initial phase of critical illness remain poorly documented in humans.\nOBJECTIVES: To determine the incidence, risk factors, and prognostic impact of diaphragmatic impairment on ICU admission.\nMETHODS: Prospective, 6-month, observational cohort study in two ICUs. Mechanically ventilated patients were studied within 24 hours after intubation (Day 1) and 48 hours later (Day 3). Seventeen anesthetized intubated control anesthesia patients were also studied. The diaphragm was assessed by twitch tracheal pressure in response to bilateral anterior magnetic phrenic nerve stimulation (Ptr,stim).\nMEASUREMENTS AND MAIN RESULTS: Eighty-five consecutive patients aged 62 (54-75) (median [interquartile range]) were evaluated (medical admission, 79%; Simplified Acute Physiology Score II, 54 [44-68]). On Day 1, Ptr,stim was 8.2 (5.9-12.3) cm H2O and 64% of patients had Ptr,stim less than 11 cm H2O. Independent predictors of low Ptr,stim were sepsis (linear regression coefficient, -3.74; standard error, 1.16; P = 0.002) and Simplified Acute Physiology Score II (linear regression coefficient, -0.07; standard error, 1.69; P = 0.03). Compared with nonsurvivors, ICU survivors had higher Ptr,stim (9.7 [6.3-13.8] vs. 7.3 [5.5-9.7] cm H2O; P = 0.004). This was also true for hospital survivors versus nonsurvivors (9.7 [6.3-13.5] vs. 7.8 [5.5-10.1] cm H2O; P = 0.004). Day 1 and Day 3 Ptr,stim were similar.\nCONCLUSIONS: A reduced capacity of the diaphragm to produce inspiratory pressure (diaphragm dysfunction) is frequent on ICU admission. It is associated with sepsis and disease severity, suggesting that it may represent another form of organ failure. It is associated with a poor prognosis. Clinical trial registered with (NCT 00786526).","DOI":"10.1164/rccm.201209-1668OC","ISSN":"1535-4970","note":"PMID: 23641946","journalAbbreviation":"Am. J. Respir. Crit. Care Med.","language":"eng","author":[{"family":"Demoule","given":"Alexandre"},{"family":"Jung","given":"Boris"},{"family":"Prodanovic","given":"Hélène"},{"family":"Molinari","given":"Nicolas"},{"family":"Chanques","given":"Gerald"},{"family":"Coirault","given":"Catherine"},{"family":"Matecki","given":"Stefan"},{"family":"Duguet","given":"Alexandre"},{"family":"Similowski","given":"Thomas"},{"family":"Jaber","given":"Samir"}],"issued":{"date-parts":[["2013",7,15]]}}},{"id":1276,"uris":[""],"uri":[""],"itemData":{"id":1276,"type":"article-journal","title":"Diaphragm weakness in mechanically ventilated critically ill patients","container-title":"Critical Care (London, England)","page":"R120","volume":"17","issue":"3","source":"PubMed","abstract":"INTRODUCTION: Studies indicate that mechanically ventilated patients develop significant diaphragm muscle weakness, but the etiology of weakness and its clinical impact remain incompletely understood. We assessed diaphragm strength in mechanically ventilated medical ICU patients, correlated the development of diaphragm weakness with multiple clinical parameters, and examined the relationship between the level of diaphragm weakness and patient outcomes.\nMETHODS: Transdiaphragmatic twitch pressure (PdiTw) in response to bilateral magnetic stimulation of the phrenic nerves was measured. Diaphragm weakness was correlated with the presence of infection, blood urea nitrogen, albumin, and glucose levels. The relationship of diaphragm strength to patient outcomes, including mortality and the duration of mechanical ventilation for successfully weaned patients, was also assessed.\nRESULTS: We found that infection is a major risk factor for diaphragm weakness in mechanically ventilated medical ICU patients. Outcomes for patients with severe diaphragm weakness (PdiTw<10 cmH2O) were poor, with a markedly increased mortality (49%) compared to patients with PdiTw≥10 cmH2O (7% mortality, P=0.022). In addition, survivors with PdiTw<10 cmH2O required a significantly longer duration of mechanical ventilation (12.3±1.7 days) than those with PdiTw≥10 cmH2O (5.5±2.0 days, P=0.016).\nCONCLUSIONS: Infection is a major cause of severe diaphragm weakness in mechanically ventilated patients. Moreover, diaphragm weakness is an important determinant of poor outcomes in this patient population.","DOI":"10.1186/cc12792","ISSN":"1466-609X","note":"PMID: 23786764\nPMCID: PMC3840677","journalAbbreviation":"Crit Care","language":"eng","author":[{"family":"Supinski","given":"Gerald S."},{"family":"Callahan","given":"Leigh Ann"}],"issued":{"date-parts":[["2013"]]}}},{"id":934,"uris":[""],"uri":[""],"itemData":{"id":934,"type":"article-journal","title":"Tracheal tube pressure change during magnetic stimulation of the phrenic nerves as an indicator of diaphragm strength on the intensive care unit","container-title":"British journal of anaesthesia","page":"876-884","volume":"87","issue":"6","source":"NCBI PubMed","abstract":"Diaphragm strength can be assessed from twitch gastric (TwPgas), twitch oesophageal (TwPoes), and twitch transdiaphragmatic pressure (TwPdi) in response to phrenic nerve stimulation. This requires the passage of balloon catheters, which may be difficult. Changes in pressure measured at the mouth during phrenic nerve stimulation avoid the need for balloon catheters. We hypothesized that pressures measured at the tracheal tube during phrenic stimulation, could also reflect oesophageal pressure change as a result of isolated diaphragmatic contraction and, therefore, reflect diaphragm strength. We aimed to establish the relationship between twitch tracheal tube pressure (TwPet), TwPoes, and TwPdi in patients in the supine and sitting positions. The phrenic nerves were stimulated magnetically bilaterally, in 14 ICU patients while supine and on another occasion while sitting up at 45 degrees. In the sitting position mean TwPoes was 9.1 cm H2O and TwPet 11.3 cm H2O (mean(SD) difference -2.2 (SD 1.5)). In the supine position mean TwPoes was 8.1 cm H2O and TwPet 9.9 cm H2O (mean difference -1.8 (2.2)). The difference between TwPoes and TwPet was less at low twitch amplitude; less than +/- 1 cm H2O below a mean twitch height of 8 cm H2O supine and 10 cm H2O sitting. Sitting TwPet was related to TwPoes r2=0.93 and TwPdi r2=0.65 (P<0.01). Supine TwPet was related to TwPoes r2=0.84 and TwPdi r2=0.83 (P<0.01). The mean within occasion coefficient of variation while sitting was TwPet=13.3%, TwPoes=13.9%, TwPdi=11.2%, and supine TwPet=11.6%, TwPoes=14.6%, TwPdi=11.8%. We conclude that TwPet reflects TwPoes during diaphragmatic stimulation and is worthy of further study to establish its place as a guide to the presence of respiratory muscle strength and fatigue.","ISSN":"0007-0912","note":"PMID: 11878690","journalAbbreviation":"Br J Anaesth","language":"eng","author":[{"family":"Mills","given":"G H"},{"family":"Ponte","given":"J"},{"family":"Hamnegard","given":"C H"},{"family":"Kyroussis","given":"D"},{"family":"Polkey","given":"M I"},{"family":"Moxham","given":"J"},{"family":"Green","given":"M"}],"issued":{"date-parts":[["2001",12]]}}},{"id":947,"uris":[""],"uri":[""],"itemData":{"id":947,"type":"article-journal","title":"Measurement of twitch transdiaphragmatic, esophageal, and endotracheal tube pressure with bilateral anterolateral magnetic phrenic nerve stimulation in patients in the intensive care unit","container-title":"Critical care medicine","page":"1325-1331","volume":"29","issue":"7","source":"NCBI PubMed","abstract":"OBJECTIVE: In the critically ill, respiratory muscle strength usually has been assessed by measuring maximum inspiratory pressure. The maneuver is volitional, and results can be unreliable. The nonvolitional technique of bilateral anterolateral magnetic stimulation of the phrenic nerves, producing twitch transdiaphragmatic pressure, has been successful in normal subjects and ambulatory patients. In this study we used the technique in the intensive care unit and explored the measurement of twitch endotracheal tube pressure as a less invasive technique to assess diaphragmatic contractility.\nDESIGN: Clinical study to quantify diaphragm strength in the intensive care unit.\nSETTING: Patients from three London teaching hospital intensive care units and high-dependency units.\nPATIENTS: Forty-one intensive care patients were recruited. Of these, 33 (20 men, 13 women) were studied.\nINTERVENTIONS: Esophageal and gastric balloon catheters were passed through the anaesthetized nose, and an endotracheal tube occlusion device was placed in the ventilation circuit, next to the endotracheal tube. Two 43-mm magnetic coils were placed anteriorly on the patient's neck, and the phrenic nerves were stimulated magnetically.\nMEASUREMENTS AND MAIN RESULTS: On phrenic nerve stimulation, twitch gastric pressure, twitch esophageal pressure, twitch transdiaphragmatic pressure, and twitch endotracheal tube pressure were measured. Forty-one consecutive patients consented to take part in the study, and twitch pressure data were obtained in 33 of these. Mean transdiaphragmatic pressure was 10.7 cm H2O, mean twitch esophageal pressure was 6.7 cm H2O, and mean twitch endotracheal tube pressure was 6.7 cm H2O. The mean difference between twitch esophageal pressure and twitch endotracheal tube pressure was 0.02 cm H2O. Correlation of the means of twitch endotracheal tube pressure to twitch esophageal pressure was 0.93, and that for twitch endotracheal tube pressure to transdiaphragmatic pressure was 0.78.\nCONCLUSIONS: Transdiaphragmatic pressure can be measured in the critically ill to give a nonvolitional assessment of diaphragm contractility, but not all patients can be studied. At present, the relationship of twitch endotracheal tube pressure to transdiaphragmatic pressure is too variable to reliably represent a less invasive measure of diaphragm strength.","ISSN":"0090-3493","note":"PMID: 11445679","journalAbbreviation":"Crit. Care Med.","language":"eng","author":[{"family":"Watson","given":"A C"},{"family":"Hughes","given":"P D"},{"family":"Louise Harris","given":"M"},{"family":"Hart","given":"N"},{"family":"Ware","given":"R J"},{"family":"Wendon","given":"J"},{"family":"Green","given":"M"},{"family":"Moxham","given":"J"}],"issued":{"date-parts":[["2001",7]]}}}],"schema":""} 4–7 Patients were studied in a standardized semi-recumbent position, as follows: end-expiratory pressure was set to zero and the patient was allowed to exhale during an end-expiratory pause. Intrinsic positive end expiratory pressure was found when at relaxed end-expiration, the endotracheal pressure could not reach the zero baseline while the endotracheal tube was disconnected from the ventilator, manually occluded and by checking the absence of respiratory effort. While the endotracheal tube was manually occluded, bilateral anterolateral magnetic stimulation was performed. The absence of active respiratory efforts in response to stimulation was determined by checking the stability of the airway pressure signal. Two operators were required to achieve both stimulation and measurements. After determining the optimal position of the coils, at least three stimulations were performed at 100% of maximal output allowed by the stimulator. Stimulations were separated by at least 60-sec to avoid superposition. The average of the three measures was taken into account for analysis. Ptr,stim was defined as the amplitude of the negative pressure wave following stimulation, taken from baseline to peak. It was measured at the proximal external end of the endotracheal tube, using a linear differential pressure transducer (MP45 ±100 cmH2O, Validyne, Northridge, Calif., USA). The pressure signal was sampled and digitized at 128 Hz (MP30, Biopac Systems, Santa Barbara, Calif., USA or Powerlab, AD Instruments, Bella Vista, Australia) for subsequent data analysis.References ADDIN ZOTERO_BIBL {"uncited":[],"omitted":[],"custom":[]} CSL_BIBLIOGRAPHY 1.Dubé B-P, Dres M, Mayaux J, Demiri S, Similowski T, Demoule A: Ultrasound evaluation of diaphragm function in mechanically ventilated patients: comparison to phrenic stimulation and prognostic implications. Thorax 2017; 72:811–82.Boles J-M, Bion J, Connors A, Herridge M, Marsh B, Melot C, Pearl R, Silverman H, Stanchina M, Vieillard-Baron A, Welte T: Weaning from mechanical ventilation. Eur Respir J 2007; 29:1033–563.De Troyer A, Kirkwood PA, Wilson TA: Respiratory action of the intercostal muscles. Physiol Rev 2005; 85:717–564.Demoule A, Jung B, Prodanovic H, Molinari N, Chanques G, Coirault C, Matecki S, Duguet A, Similowski T, Jaber S: Diaphragm dysfunction on admission to the intensive care unit. Prevalence, risk factors, and prognostic impact-a prospective study. Am J Respir Crit Care Med 2013; 188:213–95.Supinski GS, Callahan LA: Diaphragm weakness in mechanically ventilated critically ill patients. Crit Care 2013; 17:R1206.Mills GH, Ponte J, Hamnegard CH, Kyroussis D, Polkey MI, Moxham J, Green M: Tracheal tube pressure change during magnetic stimulation of the phrenic nerves as an indicator of diaphragm strength on the intensive care unit. Br J Anaesth 2001; 87:876–847.Watson AC, Hughes PD, Louise Harris M, Hart N, Ware RJ, Wendon J, Green M, Moxham J: Measurement of twitch transdiaphragmatic, esophageal, and endotracheal tube pressure with bilateral anterolateral magnetic phrenic nerve stimulation in patients in the intensive care unit. Crit Care Med 2001; 29:1325–31TablesTable E1. Intra-class correlation – intra-observer variations of parasternal intercostal muscle ultrasound measurements in healthy subjects (study A) and patients (study C)Intra-Observer #1Intra-Observer #2Inter-ObserverICC95%?CIICC95%?CIICC95%?CIStudy ATee0.970.94 to 0.990.970.94 to 0.990.920.82 to 0.96Tei0.970.94 to 0.990.970.92 to 0.990.920.82 to 0.96TFic0.860.68 to 0.940.520.12 to 0.770.770.53 to 0.89Study CTee0.790.48 to 0.920.970.92 to 0.990.840.60 to 0.94Tei0.910.77 to 0.970.970.93 to 0.990.950.88 to 0.98TFic0.920.78 to 0.970.920.77 to 0.970.920.78 to 0.97Tee: parasternal intercostal end-expiratory thickness; Tei: parasternal intercostal end-inspiratory thickness; TFic: parasternal intercostal muscle thickening fraction; ICC: intra-class correlation coefficient; CI: confidence intervalTable E2. Comparison of ROC curves of the four indices to predict spontaneous breathing trial failureVariableAUC95%?CIComparison withPtr,stimTFdiTFicTFic/TFdiPtr,stim0.910.80 to 0.97-p = 0.472p?= 0.415p = 0.851TFdi0.880.76 to 0.97--p = 0.932p = 0.402TFic0.890.76 to 0.95---p = 0.130TFic/TFdi0.920.81 to 0.96----Ptr,stim: endotracheal pressure induced by a bilateral phrenic nerve stimulation, TFdi: diaphragm thickening fraction; TFic: parasternal intercostal muscle thickening fraction; AUC: area under the receiver operating characteristics curves; CI: confidence intervalFiguresFigure E1Figure E2 ................
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