Diaphragm contractile activity during mechanical ventilation

Brouwer, Lindie Estelle (2018-03)

Thesis (MScPhysio)--Stellenbosch University, 2018.

Thesis

ENGLISH SUMMARY : Introduction: Mechanical ventilation has been shown to have detrimental effects on the diaphragm, causing extubation failure. Diaphragm ultrasound has recently been investigated as a measurement technique that could identify diaphragm dysfunction in real-time. Investigation of diaphragm function and the impact thereof on patient outcome could inform us of the behaviour of the diaphragm muscle during mechanical ventilation. Methods: A Scoping review was done to investigate the effect of mechanical ventilation on the diaphragm. Six databases were searched using a specific search strategy. Predefined inclusion criteria were used to identify papers suitable for the review. The primary investigator used a systematic process to identify suitable papers and extract data into an Excel spreadsheet. Data was used to inform the planning of the primary research study. A prospective observational cohort study was conducted to determine the effect of diaphragm contractile activity on extubation success in mechanically ventilated patients. Mechanically ventilated participants were recruited on admission to the intensive care unit. Sonographic measurements of the diaphragm were taken daily until extubation, and respiratory muscle strength measurements were taken within 24 hours of extubation. Diaphragm thickness (Tdi), diaphragm thickening fraction (DTF) and daily rate of change in both Tdi and DTF related to the previous day were calculated. Patient outcomes were reported by two variables: extubation outcome and duration of ventilation. Associations between diaphragm and inspiratory measurements were reported using Spearman’s correlations, and between-group differences were analysed by means of Mann-Whitney U tests and ANOVA graphs. A p-value of <0.05 was used to indicate significance. Results: Six hundred and thirty-seven articles were assessed for inclusion into the scoping review. Fifty-six papers were included in the review. Diaphragm assessment techniques, ventilation modes, cellular changes to the diaphragm and confounding factors were reported. Similar techniques were reported regarding diaphragm contractile activity and Tdi measurements, however results were contrasting, especially concerning patient outcome. Sixty-eight participants were included in the primary study. Fifty-four participants passed extubation. The mean age of the sample was 45.1 years (SD = 16.9). Neither age, gender, comorbidities, smoking nor alcohol use were different in success versus failed extubation groups. Baseline Tdi measurement was significantly higher in failed than successful extubation groups (p=0.033), and a significant moderately positive association was found between baseline Tdi and total duration of mechanical ventilation (r=0.412, p<0.01). Baseline DTF did not differ between failed and successful extubation groups (p>0.05). Baseline Tdi was not associated with maximal inspiratory pressure (r=0.02, p=0.901). Conclusion: Several diaphragmatic assessment techniques exist, however there are discrepancies within the results reported. Ultrasonography proves to be an easy assessment technique to visualise the diaphragm in real-time. Furthermore, we conclude that in our population, thicker diaphragms at baseline may be more prone to an increased duration of mechanical ventilation and may be linked to extubation failure. Measuring diaphragm contractile activity during tidal breathing may not be a valid indicator of extubation readiness and further research should be done to prove its value in the critically ill population.

AFRIKAANSE OPSOMMING : Inleiding: Meganiese ventilasie is bewys om nadelige effekte op die diafragma te hê, wat mislukte ekstubasie kan veroorsaak. Diafragma ultraklank is onlangs ondersoek as ‘n assesseringstegniek wat diafragma disfunksie in ware tyd kan identifiseer. Diafragma funksie en die impak daarvan op pasiënt uitkomste kan ons inlig oor die gedrag van die diafragma spier tydens meganiese ventilasie, en moet ondersoek word. Metode: ‘n Literatuur omvangsbepaling was gedoen om die effek van meganiese ventilasie op die diafragma te ondersoek. Ses databasisse was deursoek met ‘n spesifieke soektog strategie. Gedefinieerde insluitingskriteria was gebruik of gepaste artikels te identifiseer. Die primêre ondersoeker het ‘n sistematiese proses gevolg om sodoende gepaste artikels te identifiseer en data in ‘n Excel sigblad in te lees. Hierdie inligting was gebruik om die primêre studie te beplan. ‘n Voornemende waarnemings kohort studie was uitgevoer om the effek van diafragma kontraktiele aktiwiteit op ekstubasie sukses in meganies geventileerde pasiënte te bepaal. Meganies geventileerde deelnemers was gewerf tydens opname in die intensiewe sorg eenhede. Sonografiese metings van die diafragma was daagliks geneem tot in met ekstubasie, en respiratoriese krag metings was geneem binne 24 uur vanaf ekstubasie. Diafragma dikte (Tdi), diafragma verdikkingsfraksie (DTF) en daaglikse koers van verandering in diafragma dikte en verdikkingsfraksie in vergelyking met die vorige dag was bereken. Pasiënt uitkomste was deur twee veranderlikes voorgestel: ekstubasie uitkomste en duur van meganiese ventilasie. Assosiasies tussen diafragma en respiratoriese metings was gerapporteer deur “Spearman’s” korrelasies, en tussen-groep verskille was geanaliseer deur middel van “Mann-Whitney U” toetse en ANOVA grafieke. ‘n P-waarde van <0.05 was as statisties beduidend gestel. Resultate: Ses-honderd-sewe-en-dertig artikels was geassesseer vir insluiting in die omvangsbepaling. Ses-en-vyftig artikels was ingesluit. Diafragma assesserings tegnieke, ventilasie metodes, molekulêre veranderinge in die diafragma en verwarrende faktore was gerapporteer. Eenderse tegnieke met betrekking tot diafragma kontraktiele aktiwiteit en dikte metings was berig, alhoewel resultate rondom pasiënt uitkomste verskil. Agt-en-sestig deelnemers was ingesluit in die primêre studie. Vier-en-vyftig deelnemers was suksesvol geëkstubeer. The gemiddelde ouderdom van die toetsgroep was 45.1 jaar (SD = 16.9). Nie ouderdom, geslag, mede-siektetoestande, rook of alkohol gebruik was verskillend tussen suksesvolle en mislukte ekstubasie groepe nie. Basislyn dikte metings was beduidend hoër in die mislukte ekstubasie groep (p=0.033). Basislyn DTF was nie verskillend tussen suksesvolle en mislukte ekstubasie groepe nie (p>0.05). ‘n Gemiddelde positiewe assosiasie was gevind tussen basislyn dikte en totale duur van meganiese ventilasie (r=0.412, p<0.01). Basislyn dikte was nie geassosieer met maksimale inspiratoriese druk nie (r=0.02, p=0.901). Gevolgtrekking: Verskeie diafragmatiese assesseringstegnieke bestaan alhoewel daar verskille in die resultate gerapporteer is. Ultrasonografie is bewys om ‘n maklike assesseringstegniek te wees om die diafragma in ware tyd te visualiseer. Verder het ons gevind dat ‘n dikker diafragma by basislyn moontlik meer geneig is tot verlengde duur van meganiese ventilasie, en moontlik gekonnekteer kan word aan mislukte ekstubasie, in ons populasie. Deur diafragma kontraktiele aktiwiteit te meet gedurende gety asemhaling mag moontlik nie ‘n geldige aanwyser wees van ekstubasie gereedheid nie en verder navorsing word benodig om die waarde daarvan in ‘n kritieke populasie te bewys.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/103708
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