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1.
PLoS One ; 15(3): e0230147, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32160252

RESUMO

OBJECTIVES: When patients with acute respiratory distress syndrome are moved out of an intensive care unit, the ventilator often requires changing. This procedure suppresses positive end expiratory pressure and promotes lung derecruitment. Clamping the endotracheal tube may prevent this from occurring. Whether or not such clamping maintains positive end-expiratory pressure has never been investigated. We designed a bench study to explore this further. HOW THE STUDY WAS DONE: We used the Elysee 350 ventilator in 'volume controlled' mode with a positive end-expiratory pressure of 15 cmH2O, connected to an endotracheal tube with an 8 mm internal diameter inserted into a lung model with 40 ml/cmH2O compliance and 10 cmH2O/L/s resistance. We measured airway pressure and flow between the distal end of the endotracheal tube and the lung model. We tested a plastic, a metal, and an Extra Corporeal Membrane Oxygenation clamp, each with an oral/nasal, a nasal, and a reinforced endotracheal tube. We performed an end-expiratory hold then clamped the endotracheal tube and disconnected the ventilator. We measured the change in airway pressure and volume for 30 s following the disconnection of the ventilator. RESULTS: Airway pressure decreased thirty seconds after disconnection with all combinations of clamp and endotracheal tube. The largest fall in airway pressure (-17.486 cmH2O/s at 5 s and -18.834 cmH2O/s at 30 s) was observed with the plastic clamp combined with the reinforced endotracheal tube. The smallest decrease in airway pressure (0 cmH2O/s at 5 s and -0.163 cmH2O/s at 30 s) was observed using the Extra Corporeal Membrane Oxygenation clamp with the nasal endotracheal tube. CONCLUSIONS: Only the Extra Corporeal Membrane Oxygenation clamp was efficient. Even with an Extra Corporeal Membrane Oxygenation clamp, it is important to limit the duration the ventilator is disconnected to a few seconds (ideally 5 s).


Assuntos
Intubação Intratraqueal/métodos , Respiração com Pressão Positiva/métodos , Respiração Artificial/métodos , Humanos , Unidades de Terapia Intensiva , Pulmão/fisiologia , Modelos Biológicos , Pressão , Troca Gasosa Pulmonar/fisiologia , Respiração , Síndrome do Desconforto Respiratório do Adulto/terapia , Mecânica Respiratória/fisiologia , Volume de Ventilação Pulmonar/fisiologia , Ventiladores Mecânicos
2.
Anesthesiology ; 132(4): 808-824, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32101968

RESUMO

BACKGROUND: In acute respiratory failure elevated intraabdominal pressure aggravates lung collapse, tidal recruitment, and ventilation inhomogeneity. Low positive end-expiratory pressure (PEEP) may promote lung collapse and intrapulmonary shunting, whereas high PEEP may increase dead space by inspiratory overdistension. The authors hypothesized that an electrical impedance tomography-guided PEEP approach minimizing tidal recruitment improves regional ventilation and perfusion matching when compared to a table-based low PEEP/no recruitment and an oxygenation-guided high PEEP/full recruitment strategy in a hybrid model of lung injury and elevated intraabdominal pressure. METHODS: In 15 pigs with oleic acid-induced lung injury intraabdominal pressure was increased by intraabdominal saline infusion. PEEP was set in randomized order: (1) guided by a PEEP/inspired oxygen fraction table, without recruitment maneuver; (2) minimizing tidal recruitment guided by electrical impedance tomography after a recruitment maneuver; and (3) maximizing oxygenation after a recruitment maneuver. Single photon emission computed tomography was used to analyze regional ventilation, perfusion, and aeration. Primary outcome measures were differences in PEEP levels and regional ventilation/perfusion matching. RESULTS: Resulting PEEP levels were different (mean ± SD) with (1) table PEEP: 11 ± 3 cm H2O; (2) minimal tidal recruitment PEEP: 22 ± 3 cm H2O; and (3) maximal oxygenation PEEP: 25 ± 4 cm H2O; P < 0.001. Table PEEP without recruitment maneuver caused highest lung collapse (28 ± 11% vs. 5 ± 5% vs. 4 ± 4%; P < 0.001), shunt perfusion (3.2 ± 0.8 l/min vs. 1.0 ± 0.8 l/min vs. 0.7 ± 0.6 l/min; P < 0.001) and dead space ventilation (2.9 ± 1.0 l/min vs. 1.5 ± 0.7 l/min vs. 1.7 ± 0.8 l/min; P < 0.001). Although resulting in different PEEP levels, minimal tidal recruitment and maximal oxygenation PEEP, both following a recruitment maneuver, had similar effects on regional ventilation/perfusion matching. CONCLUSIONS: When compared to table PEEP without a recruitment maneuver, both minimal tidal recruitment PEEP and maximal oxygenation PEEP following a recruitment maneuver decreased shunting and dead space ventilation, and the effects of minimal tidal recruitment PEEP and maximal oxygenation PEEP were comparable.


Assuntos
Lesão Pulmonar/metabolismo , Lesão Pulmonar/terapia , Respiração com Pressão Positiva/métodos , Troca Gasosa Pulmonar/fisiologia , Mecânica Respiratória/fisiologia , Animais , Feminino , Lesão Pulmonar/diagnóstico por imagem , Masculino , Suínos , Volume de Ventilação Pulmonar/fisiologia
3.
Anesthesiology ; 132(4): 667-677, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32011334

RESUMO

BACKGROUND: Pneumoperitoneum for laparoscopic surgery is associated with a rise of driving pressure. The authors aimed to assess the effects of positive end-expiratory pressure (PEEP) on driving pressure at varying intraabdominal pressure levels. It was hypothesized that PEEP attenuates pneumoperitoneum-related rises in driving pressure. METHODS: Open-label, nonrandomized, crossover, clinical trial in patients undergoing laparoscopic cholecystectomy. "Targeted PEEP" (2 cm H2O above intraabdominal pressure) was compared with "standard PEEP" (5 cm H2O), with respect to the transpulmonary and respiratory system driving pressure at three predefined intraabdominal pressure levels, and each patient was ventilated with two levels of PEEP at the three intraabdominal pressure levels in the same sequence. The primary outcome was the difference in transpulmonary driving pressure between targeted PEEP and standard PEEP at the three levels of intraabdominal pressure. RESULTS: Thirty patients were included and analyzed. Targeted PEEP was 10, 14, and 17 cm H2O at intraabdominal pressure of 8, 12, and 15 mmHg, respectively. Compared to standard PEEP, targeted PEEP resulted in lower median transpulmonary driving pressure at intraabdominal pressure of 8 mmHg (7 [5 to 8] vs. 9 [7 to 11] cm H2O; P = 0.010; difference 2 [95% CI 0.5 to 4 cm H2O]); 12 mmHg (7 [4 to 9] vs.10 [7 to 12] cm H2O; P = 0.002; difference 3 [1 to 5] cm H2O); and 15 mmHg (7 [6 to 9] vs.12 [8 to 15] cm H2O; P < 0.001; difference 4 [2 to 6] cm H2O). The effects of targeted PEEP compared to standard PEEP on respiratory system driving pressure were comparable to the effects on transpulmonary driving pressure, though respiratory system driving pressure was higher than transpulmonary driving pressure at all intraabdominal pressure levels. CONCLUSIONS: Transpulmonary driving pressure rises with an increase in intraabdominal pressure, an effect that can be counterbalanced by targeted PEEP. Future studies have to elucidate which combination of PEEP and intraabdominal pressure is best in term of clinical outcomes.


Assuntos
Abdome/fisiopatologia , Laparoscopia/métodos , Monitorização Intraoperatória/métodos , Pneumoperitônio/fisiopatologia , Respiração com Pressão Positiva/métodos , Idoso , Estudos Cross-Over , Feminino , Humanos , Laparoscopia/efeitos adversos , Masculino , Pessoa de Meia-Idade , Pneumoperitônio/diagnóstico , Pneumoperitônio/etiologia , Respiração com Pressão Positiva/efeitos adversos , Volume de Ventilação Pulmonar/fisiologia
4.
Anesth Analg ; 130(5): 1396-1406, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31904632

RESUMO

BACKGROUND: Mechanical ventilation with low tidal volumes appears to provide benefit in patients having noncardiac surgery; however, whether it is beneficial in patients having cardiac surgery is unclear. METHODS: We retrospectively examined patients having elective cardiac surgery requiring cardiopulmonary bypass through a median sternotomy approach who received mechanical ventilation with a single lumen endotracheal tube from January 2010 to mid-August 2016. Time-weighted average tidal volume (milliliter per kilogram predicted body weight [PBW]) during the duration of surgery excluding cardiopulmonary bypass was analyzed. The association between tidal volumes and postoperative oxygenation (measured by arterial partial pressure of oxygen (PaO2)/fraction of inspired oxygen ratio [PaO2/FIO2]), impaired oxygenation (PaO2/FIO2 <300), and clinical outcomes were examined. RESULTS: Of 9359 cardiac surgical patients, larger tidal volumes were associated with slightly worse postoperative oxygenation. Postoperative PaO2/FIO2 decreased an estimated 1.05% per 1 mL/kg PBW increase in tidal volume (97.5% confidence interval [CI], -1.74 to -0.37; PBon = .0005). An increase in intraoperative tidal volumes was also associated with increased odds of impaired oxygenation (odds ratio [OR; 97.5% CI]: 1.08 [1.02-1.14] per 1 mL/kg PBW increase in tidal volume; PBon = .0029), slightly longer intubation time (5% per 1 mL/kg increase in tidal volume (hazard ratio [98.33% CI], 0.95 [0.93-0.98] per 1 mL/kg PBW; PBon < .0001), and increased mortality (OR [98.33% CI], 1.34 [1.06-1.70] per 1 mL/kg PBW increase in tidal volume; PHolm = .0144). An increase in intraoperative tidal volumes was also associated with acute postoperative respiratory failure (OR [98.33% CI], 1.16 [1.03-1.32] per 1 mL/kg PBW increase in tidal volume; PHolm = .0146), but not other pulmonary complications. CONCLUSIONS: Lower time-weighted average intraoperative tidal volumes were associated with a very modest improvement in postoperative oxygenation in patients having cardiac surgery.


Assuntos
Procedimentos Cirúrgicos Cardíacos/métodos , Monitorização Intraoperatória/métodos , Consumo de Oxigênio/fisiologia , Volume de Ventilação Pulmonar/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Procedimentos Cirúrgicos Cardíacos/efeitos adversos , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto Jovem
5.
Anesthesiology ; 132(2): 307-320, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31939846

RESUMO

BACKGROUND: Pressure-support ventilation may worsen lung damage due to increased dynamic transpulmonary driving pressure. The authors hypothesized that, at the same tidal volume (VT) and dynamic transpulmonary driving pressure, pressure-support and pressure-controlled ventilation would yield comparable lung damage in mild lung injury. METHODS: Male Wistar rats received endotoxin intratracheally and, after 24 h, were ventilated in pressure-support mode. Rats were then randomized to 2 h of pressure-controlled ventilation with VT, dynamic transpulmonary driving pressure, dynamic transpulmonary driving pressure, and inspiratory time similar to those of pressure-support ventilation. The primary outcome was the difference in dynamic transpulmonary driving pressure between pressure-support and pressure-controlled ventilation at similar VT; secondary outcomes were lung and diaphragm damage. RESULTS: At VT = 6 ml/kg, dynamic transpulmonary driving pressure was higher in pressure-support than pressure-controlled ventilation (12.0 ± 2.2 vs. 8.0 ± 1.8 cm H2O), whereas static transpulmonary driving pressure did not differ (6.7 ± 0.6 vs. 7.0 ± 0.3 cm H2O). Diffuse alveolar damage score and gene expression of markers associated with lung inflammation (interleukin-6), alveolar-stretch (amphiregulin), epithelial cell damage (club cell protein 16), and fibrogenesis (metalloproteinase-9 and type III procollagen), as well as diaphragm inflammation (tumor necrosis factor-α) and proteolysis (muscle RING-finger-1) were comparable between groups. At similar dynamic transpulmonary driving pressure, as well as dynamic transpulmonary driving pressure and inspiratory time, pressure-controlled ventilation increased VT, static transpulmonary driving pressure, diffuse alveolar damage score, and gene expression of markers of lung inflammation, alveolar stretch, fibrogenesis, diaphragm inflammation, and proteolysis compared to pressure-support ventilation. CONCLUSIONS: In the mild lung injury model use herein, at the same VT, pressure-support compared to pressure-controlled ventilation did not affect biologic markers. However, pressure-support ventilation was associated with a major difference between static and dynamic transpulmonary driving pressure; when the same dynamic transpulmonary driving pressure and inspiratory time were used for pressure-controlled ventilation, greater lung and diaphragm injury occurred compared to pressure-support ventilation.


Assuntos
Diafragma/lesões , Diafragma/fisiopatologia , Lesão Pulmonar/etiologia , Lesão Pulmonar/fisiopatologia , Respiração com Pressão Positiva/efeitos adversos , Respiração com Pressão Positiva/métodos , Animais , Masculino , Respiração com Pressão Positiva/normas , Ratos , Ratos Wistar , Mecânica Respiratória/fisiologia , Volume de Ventilação Pulmonar/fisiologia
6.
Br J Anaesth ; 124(3): 336-344, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31918847

RESUMO

BACKGROUND: General anaesthesia is increasingly common in elderly and obese patients. Greater age and body mass index (BMI) worsen gas exchange. We assessed whether this is related to increasing atelectasis during general anaesthesia. METHODS: This primary analysis included pooled data from previously published studies of 243 subjects aged 18-78 yr, with BMI of 18-52 kg m-2. The subjects had no clinical signs of cardiopulmonary disease, and they underwent computed tomography (CT) awake and during anaesthesia before surgery after preoxygenation with an inspired oxygen fraction (FIO2) of >0.8, followed by mechanical ventilation with FIO2 of 0.3 or higher with no PEEP. Atelectasis was assessed by CT. RESULTS: Atelectasis area of up to 39 cm2 in a transverse scan near the diaphragm was seen in 90% of the subjects during anaesthesia. The log of atelectasis area was related to a quadratic function of (age+age2) with the most atelectasis at ∼50 yr (r2=0.08; P<0.001). Log atelectasis area was also related to a broken-line function of the BMI with the knee at 30 kg m-2 (r2=0.06; P<0.001). Greater atelectasis was seen in the subjects receiving FIO2 of 1.0 than FIO2 of 0.3-0.5 (12.8 vs 8.1 cm2; P<0.001). A multiple regression analysis, including a quadratic function of age, a broken-line function of the BMI, and dichotomised FIO2 (0.3-0.5/1.0) adjusting for ventilatory frequency, strengthened the association (r2=0.23; P<0.001). PaO2 decreased with both age and BMI. CONCLUSIONS: Atelectasis during general anaesthesia increased with age up to 50 yr and decreased beyond that. Atelectasis increased with BMI in normal and overweight patients, but showed no further increase in obese subjects (BMI ≥30 kg m-2). Therefore, greater age and obesity appear to limit atelectasis formation during general anaesthesia.


Assuntos
Anestesia Geral/efeitos adversos , Obesidade/complicações , Complicações Pós-Operatórias/prevenção & controle , Atelectasia Pulmonar/etiologia , Adolescente , Adulto , Distribuição por Idade , Fatores Etários , Idoso , Anestesia Geral/métodos , Índice de Massa Corporal , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade/fisiopatologia , Complicações Pós-Operatórias/diagnóstico por imagem , Complicações Pós-Operatórias/etiologia , Atelectasia Pulmonar/diagnóstico por imagem , Atelectasia Pulmonar/fisiopatologia , Atelectasia Pulmonar/prevenção & controle , Troca Gasosa Pulmonar/fisiologia , Respiração Artificial/métodos , Fumar/efeitos adversos , Volume de Ventilação Pulmonar/fisiologia , Tomografia Computadorizada por Raios X , Adulto Jovem
7.
PLoS One ; 15(1): e0228111, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31990926

RESUMO

BACKGROUND: The aim of this study was to investigate whether 33% duty cycle increases end-tidal carbon dioxide (ETCO2) level, a surrogate measurement for cardiac output during cardiopulmonary resuscitation (CPR), compared with 50% duty cycle. METHODS: Six pigs were randomly assigned to the DC33 or DC50 group. After 3 min of induced ventricular fibrillation (VF), CPR was performed for 5 min with 33% duty cycle (DC33 group) or with 50% duty cycle (DC50 group) (phase I). Defibrillation was delivered until return of spontaneous circulation (ROSC) thereafter. After 30 min of stabilization, the animals were re-assigned to the opposite groups. VF was induced again, and CPR was performed (phase II). The primary outcome was ETCO2 during CPR, and the secondary outcomes were coronary perfusion pressure (CPP), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and right atrial pressure (RAP). RESULTS: Mean ETCO2 was higher in the DC33 group compared with the DC50 group (22.5 mmHg vs 21.5 mmHg, P = 0.018). In a linear mixed model, 33% duty cycle increased ETCO2 by 1.0 mmHg compared with 50% duty cycle (P < 0.001). ETCO2 increased over time in the DC33 group [0.6 mmHg/min] while ETCO2 decreased in the DC50 group [-0.6 mmHg/min] (P < 0.001). Duty cycle of 33% increased SAP (6.0 mmHg, P < 0.001), DAP (8.9 mmHg, P < 0.001) RAP (2.6 mmHg, P < 0.001) and CPP (4.7 mmHg, P < 0.001) compared with the duty cycle of 50%. CONCLUSION: Duty cycle of 33% increased ETCO2, a surrogate measurement for cardiac output during CPR, compared with duty cycle of 50%. Moreover, ETCO2 increased over time during CPR with 33% duty cycle while ETCO2 decreased with 50% duty cycle.


Assuntos
Dióxido de Carbono/análise , Débito Cardíaco/fisiologia , Reanimação Cardiopulmonar/métodos , Fibrilação Ventricular/terapia , Fibrilação Ventricular/veterinária , Animais , Pressão Arterial/fisiologia , Pressão Atrial/fisiologia , Capnografia , Dióxido de Carbono/fisiologia , Circulação Cerebrovascular/fisiologia , Modelos Animais de Doenças , Masculino , Monitorização Fisiológica , Estudos Prospectivos , Suínos , Volume de Ventilação Pulmonar/fisiologia , Fibrilação Ventricular/fisiopatologia
8.
Arch Dis Child Fetal Neonatal Ed ; 105(3): 248-252, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31256011

RESUMO

OBJECTIVE: To assess the predictive value of tidal volume (Vt) of spontaneous breaths at birth in infants with congenital diaphragmatic hernia (CDH). DESIGN: Prospective study. SETTING: Tertiary neonatal intensive care unit. PATIENTS: Thirty infants with antenatally diagnosed CDH born at Hospital Sant Joan de Déu in Barcelona from September 2013 to September 2015. INTERVENTIONS: Spontaneous breaths and inflations given in the first 10 min after intubation at birth were recorded using respiratory function monitor. Only expired Vt of uninterrupted spontaneous breaths was included for analysis. Receiver operating characteristics (ROC) analysis was performed and the area under the curve (AUC) was estimated to assess the predictive accuracy of Vt. MAIN OUTCOME MEASURES: Mortality before hospital discharge and chronic lung disease (CLD) at day 28 of life. RESULTS: There were 1.233 uninterrupted spontaneous breaths measured, and the overall mean Vt was 2.8±2.1 mL/kg. A lower Vt was found in infants who died (n=14) compared with survivors (n=16) (1.7±1.6 vs 3.7±2.1 mL/kg; p=0.008). Vt was lower in infants who died during admission or had CLD (n=20) compared with survivors without CLD (n=10) (2.0±1.7 vs 4.3±2.2 mL/kg; p=0.004). ROC analysis showed that Vt ≤2.2 mL/kg predicted mortality with 79% sensitivity and 81% specificity (AUC=0.77, p=0.013). Vt ≤3.4 mL/kg was a good predictor of death or CLD (AUC=0.80, p=0.008) with 85% sensitivity and 70% specificity. CONCLUSION: Vt of spontaneous breaths measured immediately after birth is associated with mortality and CLD. Vt seems to be a reliable predictor but is not an independent predictor after adjustment for observed/expected lung to head ratio and liver position.


Assuntos
Hérnias Diafragmáticas Congênitas/mortalidade , Hérnias Diafragmáticas Congênitas/fisiopatologia , Volume de Ventilação Pulmonar/fisiologia , Doença Crônica , Feminino , Cabeça/anatomia & histologia , Hérnias Diafragmáticas Congênitas/complicações , Humanos , Recém-Nascido , Unidades de Terapia Intensiva Neonatal , Intubação Intratraqueal , Pulmão/anatomia & histologia , Pneumopatias/etiologia , Masculino , Diagnóstico Pré-Natal , Estudos Prospectivos , Curva ROC
9.
Arch Dis Child Fetal Neonatal Ed ; 105(3): 253-258, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31285225

RESUMO

OBJECTIVE: To analyse the performance of the Fabian +NCPAP evolution ventilator during volume guarantee (VG) ventilation in neonates at maintaining the target tidal volume and what tidal and minute volumes are required to maintain normocapnia. METHODS: Clinical and ventilator data were collected and analysed from 83 infants receiving VG ventilation during interhospital transfer. Sedation was used in 26 cases. Ventilator data were downloaded with a sampling rate of 0.5 Hz. Data were analysed using the Python computer language and its data analysis packages. RESULTS: ~107 hours of ventilator data were analysed, consisting of ~194 000 data points. The median absolute difference between the actual expiratory tidal volume (VTe) of the ventilator inflations and the target tidal volume (VTset) was 0.29 mL/kg (IQR: 0.11-0.79 mL/kg). Overall, VTe was within 1 mL/kg of VTset in 80% of inflations. VTe decreased progressively below the target when the endotracheal tube leak exceeded 50%. When leak was below 50%, VTe was below VTset by >1 mL/kg in less than 12% of inflations even in babies weighing less than 1000 g. Both VTe (r=-0.34, p=0.0022) and minute volume (r=-0.22, p=0.0567) showed a weak inverse correlation with capillary partial pressure of carbon dioxide (Pco2) values. Only 50% of normocapnic blood gases were associated with tidal volumes between 4 and 6 mL/kg. CONCLUSIONS: The Fabian ventilator delivers volume-targeted ventilation with high accuracy if endotracheal tube leakage is not excessive and the maximum allowed inflating pressure does not limit inflations. There is only weak inverse correlation between tidal or minute volumes and Pco2.


Assuntos
Dióxido de Carbono/sangue , Volume de Ventilação Pulmonar/fisiologia , Ventiladores Mecânicos/estatística & dados numéricos , Humanos , Recém-Nascido , Insuflação , Intubação Intratraqueal/normas , Oxigênio/sangue , Ventiladores Mecânicos/classificação
10.
Eur J Radiol ; 122: 108748, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31775082

RESUMO

PURPOSE: Acute respiratory distress syndrome (ARDS) is an acute inflammatory lung injury that frequently shows fatal outcomes. As radiographic predictive factors, some reports have focused on the region of ill-aerated lung, but none have focused on well-aerated lung. Our objective was to evaluate the relationship between computed tomography (CT) volume of the well-aerated lung region and prognosis in patients with ARDS. METHOD: This retrospective observational study of a single intensive care unit (ICU) included patients with ARDS treated between April 2011 and May 2013. We identified 42 patients with ARDS for whom adequate helical CT scans were available. CT images were analyzed for 3-dimensional reconstruction, and lung region volumes were measured using automated volumetry methods. Lung regions were identified by CT attenuation in Hounsfield units (HU). RESULTS: Of the 42 patients, 35 (83.3 %) survived 28 days and 32 (76.2 %) survived to ICU discharge. CT lung volumetry was performed within 144.5 ±â€¯76.6 s, and inter-rater reliability of CT lung volumetry for lung regions below -500 HU (well-aerated lung region) were near-perfect. Well-aerated lung region showed a positive correlation with 28-day survival (P = 0.020), and lung volumes below -900 HU correlated positively with 28-day survival and ICU survival, respectively (P = 0.028, 0.017). Survival outcome was better for percentage of well-aerated lung region/predicted total lung capacity ≥40 % than for <40 % (P = 0.039). CONCLUSIONS: CT lung volumetry of the well-aerated lung region using an automated method allows fast, reliable quantitative CT analysis and potentially prediction of the clinical course in patients with ARDS.


Assuntos
Síndrome do Desconforto Respiratório do Adulto/diagnóstico por imagem , Tomografia Computadorizada Espiral/métodos , Adulto , Feminino , Humanos , Pulmão/diagnóstico por imagem , Medidas de Volume Pulmonar/métodos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Estudos Retrospectivos , Volume de Ventilação Pulmonar/fisiologia , Capacidade Pulmonar Total
11.
Respir Physiol Neurobiol ; 271: 103303, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31546026

RESUMO

Flow Controlled Expiration (FLEX) has been demonstrated to be lungprotective in models of ARDS during controlled mechanical ventilation. However, modern ventilation strategies in critical care include spontaneous breathing. Therefore, we investigated breathing discomfort and potential performance constraints of FLEX in 24 healthy test persons under increased ventilation demand. The subjects generated 20, 50 or 100 W pedal power on a bicycle ergometer while breathing with and without FLEX and rated breathing discomfort on a scale ranging from 0 (comfortable) to 10 (not tolerable). Then the subjects were asked to indicate the power they could maintain for 30 min with and without FLEX. With FLEX, tidal volume was higher and respiratory rate lower than without. Breathing discomfort was slightly increased by FLEX (on average from 2.2 to 3.2, p = 0.002). The estimated maintainable power was similar with and without FLEX (p = 0.986). We conclude that FLEX does not intolerably increase breathing discomfort and does not impair physical performance.


Assuntos
Ciclismo/fisiologia , Teste de Esforço/métodos , Exercício Físico/fisiologia , Expiração/fisiologia , Fluxo Expiratório Forçado/fisiologia , Volume de Ventilação Pulmonar/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
12.
Respir Physiol Neurobiol ; 271: 103312, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31585171

RESUMO

For the first time, impedance pneumography (IP) enables a continuous analysis of the tidal breathing flow volume (TBFV), overnight. We studied how corticosteroid inhalation treatments, sleep stage, and time from sleep onset modify the nocturnal TBFV profiles of children. Seventy children, 1-5 years old and with recurrent wheezing, underwent three, full-night TBFVs recordings at home, using IP. The first recorded one week before ending a 3-months inhaled corticosteroids treatment, and remaining two, 2 and 4 weeks after treatment. TBFV profiles were grouped by hour from sleep onset and estimated sleep stage. Compared with on-medication, the off-medication profiles showed lower volume at exhalation peak flow, earlier interruption of expiration, and less convex middle expiration. The differences in the first two features were significant during non-rapid eye movement (NREM), and the differences in the third were more prominent during REM after 4 h of sleep. These combinations of TBFV features, sleep phase, and sleep time potentially indicate airflow limitation in young children.


Assuntos
Impedância Elétrica , Taxa Respiratória/fisiologia , Sons Respiratórios/diagnóstico , Sons Respiratórios/fisiopatologia , Fases do Sono/fisiologia , Volume de Ventilação Pulmonar/fisiologia , Bronquite/diagnóstico , Bronquite/fisiopatologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Estudos Longitudinais , Masculino
13.
Crit Care ; 23(1): 424, 2019 12 27.
Artigo em Inglês | MEDLINE | ID: mdl-31881909

RESUMO

BACKGROUND: In patients with acute respiratory distress syndrome (ARDS), low tidal volume ventilation has been associated with reduced mortality. Driving pressure (tidal volume normalized to respiratory system compliance) may be an even stronger predictor of ARDS survival than tidal volume. We sought to study whether these associations hold true in acute respiratory failure patients without ARDS. METHODS: This is a retrospectively cohort analysis of mechanically ventilated adult patients admitted to ICUs from 12 hospitals over 2 years. We used natural language processing of chest radiograph reports and data from the electronic medical record to identify patients who had ARDS. We used multivariable logistic regression and generalized linear models to estimate associations between tidal volume, driving pressure, and respiratory system compliance with adjusted 30-day mortality using covariates of Acute Physiology Score (APS), Charlson Comorbidity Index (CCI), age, and PaO2/FiO2 ratio. RESULTS: We studied 2641 patients; 48% had ARDS (n = 1273). Patients with ARDS had higher mean APS (25 vs. 23, p < .001) but similar CCI (4 vs. 3, p = 0.6) scores. For non-ARDS patients, tidal volume was associated with increased adjusted mortality (OR 1.18 per 1 mL/kg PBW increase in tidal volume, CI 1.04 to 1.35, p = 0.010). We observed no association between driving pressure or respiratory compliance and mortality in patients without ARDS. In ARDS patients, both ΔP (OR1.1, CI 1.06-1.14, p < 0.001) and tidal volume (OR 1.17, CI 1.04-1.31, p = 0.007) were associated with mortality. CONCLUSIONS: In a large retrospective analysis of critically ill non-ARDS patients receiving mechanical ventilation, we found that tidal volume was associated with 30-day mortality, while driving pressure was not.


Assuntos
Respiração Artificial/mortalidade , Insuficiência Respiratória/fisiopatologia , Volume de Ventilação Pulmonar/fisiologia , Idoso , Estudos de Coortes , Feminino , Humanos , Idaho , Masculino , Pessoa de Meia-Idade , Respiração com Pressão Positiva/mortalidade , Respiração com Pressão Positiva/normas , Respiração Artificial/normas , Respiração Artificial/estatística & dados numéricos , Insuficiência Respiratória/mortalidade , Insuficiência Respiratória/terapia , Estudos Retrospectivos , Resultado do Tratamento , Utah
14.
Crit Care ; 23(1): 338, 2019 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-31666136

RESUMO

BACKGROUND: Adaptive mechanical ventilation automatically adjusts respiratory rate (RR) and tidal volume (VT) to deliver the clinically desired minute ventilation, selecting RR and VT based on Otis' equation on least work of breathing. However, the resulting VT may be relatively high, especially in patients with more compliant lungs. Therefore, a new mode of adaptive ventilation (adaptive ventilation mode 2, AVM2) was developed which automatically minimizes inspiratory power with the aim of ensuring lung-protective combinations of VT and RR. The aim of this study was to investigate whether AVM2 reduces VT, mechanical power, and driving pressure (ΔPstat) and provides similar gas exchange when compared to adaptive mechanical ventilation based on Otis' equation. METHODS: A prospective randomized cross-over study was performed in 20 critically ill patients on controlled mechanical ventilation, including 10 patients with acute respiratory distress syndrome (ARDS). Each patient underwent 1 h of mechanical ventilation with AVM2 and 1 h of adaptive mechanical ventilation according to Otis' equation (adaptive ventilation mode, AVM). At the end of each phase, we collected data on VT, mechanical power, ΔP, PaO2/FiO2 ratio, PaCO2, pH, and hemodynamics. RESULTS: Comparing adaptive mechanical ventilation with AVM2 to the approach based on Otis' equation (AVM), we found a significant reduction in VT both in the whole study population (7.2 ± 0.9 vs. 8.2 ± 0.6 ml/kg, p <  0.0001) and in the subgroup of patients with ARDS (6.6 ± 0.8 ml/kg with AVM2 vs. 7.9 ± 0.5 ml/kg with AVM, p <  0.0001). Similar reductions were observed for ΔPstat (whole study population: 11.5 ± 1.6 cmH2O with AVM2 vs. 12.6 ± 2.5 cmH2O with AVM, p <  0.0001; patients with ARDS: 11.8 ± 1.7 cmH2O with AVM2 and 13.3 ± 2.7 cmH2O with AVM, p = 0.0044) and total mechanical power (16.8 ± 3.9 J/min with AVM2 vs. 18.6 ± 4.6 J/min with AVM, p = 0.0024; ARDS: 15.6 ± 3.2 J/min with AVM2 vs. 17.5 ± 4.1 J/min with AVM, p = 0.0023). There was a small decrease in PaO2/FiO2 (270 ± 98 vs. 291 ± 102 mmHg with AVM, p = 0.03; ARDS: 194 ± 55 vs. 218 ± 61 with AVM, p = 0.008) and no differences in PaCO2, pH, and hemodynamics. CONCLUSIONS: Adaptive mechanical ventilation with automated minimization of inspiratory power may lead to more lung-protective ventilator settings when compared with adaptive mechanical ventilation according to Otis' equation. TRIAL REGISTRATION: The study was registered at the German Clinical Trials Register ( DRKS00013540 ) on December 1, 2017, before including the first patient.


Assuntos
Respiração Artificial/métodos , Idoso , Estudos Cross-Over , Feminino , Alemanha , Hemodinâmica/fisiologia , Humanos , Complacência Pulmonar/fisiologia , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Medicina de Precisão/métodos , Medicina de Precisão/tendências , Estudos Prospectivos , Respiração Artificial/tendências , Mecânica Respiratória/fisiologia , Volume de Ventilação Pulmonar/fisiologia
15.
Sensors (Basel) ; 19(23)2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31766452

RESUMO

This work proposes adapting an existing sensor and embedding it on mannequins used in cardiopulmonary resuscitation (CPR) training to accurately measure the amount of air supplied to the lungs during ventilation. Mathematical modeling, calibration, and validation of the sensor along with metrology, statistical inference, and spirometry techniques were used as a base for aquiring scientific knowledge of the system. The system directly measures the variable of interest (air volume) and refers to spirometric techniques in the elaboration of its model. This improves the realism of the dummies during the CPR training, because it estimates, in real-time, not only the volume of air entering in the lungs but also the Forced Vital Capacity (FVC), Forced Expiratory Volume (FEVt) and Medium Forced Expiratory Flow (FEF20-75%). The validation of the sensor achieved results that address the requirements for this application, that is, the error below 3.4% of full scale. During the spirometric tests, the system presented the measurement results of (305 ± 22, 450 ± 23, 603 ± 24, 751 ± 26, 922 ± 27, 1021 ± 30, 1182 ± 33, 1326 ± 36, 1476 ± 37, 1618 ± 45 and 1786 ± 56) × 10-6 m3 for reference values of (300, 450, 600, 750, 900, 1050, 1200, 1350, 1500, 1650 and 1800) × 10-6 m3, respectively. Therefore, considering the spirometry and pressure boundary conditions of the manikin lungs, the system achieves the objective of simulating valid spirometric data for debriefings, that is, there is an agreement between the measurement results when compared to the signal generated by a commercial spirometer (Koko brand). The main advantages that this work presents in relation to the sensors commonly used for this purpose are: (i) the reduced cost, which makes it possible, for the first time, to use a respiratory volume sensor in medical simulators or training dummies; (ii) the direct measurement of air entering the lung using a noninvasive method, which makes it possible to use spirometry parameters to characterize simulated human respiration during the CPR training; and (iii) the measurement of spirometric parameters (FVC, FEVt, and FEF20-75%), in real-time, during the CPR training, to achieve optimal ventilation performance. Therefore, the system developed in this work addresses the minimum requirements for the practice of ventilation in the CPR maneuvers and has great potential in several future applications.


Assuntos
Reanimação Cardiopulmonar/instrumentação , Pulmão/fisiologia , Espirometria/instrumentação , Espirometria/métodos , Idoso , Retroalimentação , Humanos , Masculino , Manequins , Testes de Função Respiratória/métodos , Volume de Ventilação Pulmonar/fisiologia , Ventilação/instrumentação , Capacidade Vital/fisiologia
16.
Int J Mol Sci ; 20(23)2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31766467

RESUMO

Adaptive support ventilation (ASV) is a closed-loop ventilation, which can make automatic adjustments in tidal volume (VT) and respiratory rate based on the minimal work of breathing. The purpose of this research was to study whether ASV can provide a protective ventilation pattern to decrease the risk of ventilator-induced lung injury in patients of acute respiratory distress syndrome (ARDS). In the clinical study, 15 ARDS patients were randomly allocated to an ASV group or a pressure-control ventilation (PCV) group. There was no significant difference in the mortality rate and respiratory parameters between these two groups, suggesting the feasible use of ASV in ARDS. In animal experiments of 18 piglets, the ASV group had a lower alveolar strain compared with the volume-control ventilation (VCV) group. The ASV group exhibited less lung injury and greater alveolar fluid clearance compared with the VCV group. Tissue analysis showed lower expression of matrix metalloproteinase 9 and higher expression of claudin-4 and occludin in the ASV group than in the VCV group. In conclusion, the ASV mode is capable of providing ventilation pattern fitting into the lung-protecting strategy; this study suggests that ASV mode may effectively reduce the risk or severity of ventilator-associated lung injury in animal models.


Assuntos
Pulmão/fisiopatologia , Respiração Artificial/métodos , Síndrome do Desconforto Respiratório do Adulto/terapia , Volume de Ventilação Pulmonar/fisiologia , Lesão Pulmonar Induzida por Ventilação Mecânica/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Claudina-4/metabolismo , Feminino , Humanos , Pulmão/metabolismo , Masculino , Metaloproteinase 9 da Matriz/metabolismo , Pessoa de Meia-Idade , Ocludina/metabolismo , Respiração , Síndrome do Desconforto Respiratório do Adulto/metabolismo , Síndrome do Desconforto Respiratório do Adulto/fisiopatologia , Suínos , Lesão Pulmonar Induzida por Ventilação Mecânica/metabolismo , Lesão Pulmonar Induzida por Ventilação Mecânica/fisiopatologia
17.
Crit Care ; 23(1): 375, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31775830

RESUMO

BACKGROUND: In ARDS patients, changes in respiratory mechanical properties and ventilatory settings can cause incomplete lung deflation at end-expiration. Both can promote dynamic hyperinflation and intrinsic positive end-expiratory pressure (PEEP). The aim of this study was to investigate, in a large population of ARDS patients, the presence of intrinsic PEEP, possible associated factors (patients' characteristics and ventilator settings), and the effects of two different external PEEP levels on the intrinsic PEEP. METHODS: We made a secondary analysis of published data. Patients were ventilated with a tidal volume of 6-8 mL/kg of predicted body weight, sedated, and paralyzed. After a recruitment maneuver, a PEEP trial was run at 5 and 15 cmH2O, and partitioned mechanics measurements were collected after 20 min of stabilization. Lung computed tomography scans were taken at 5 and 45 cmH2O. Patients were classified into two groups according to whether or not they had intrinsic PEEP at the end of an expiratory pause. RESULTS: We enrolled 217 sedated, paralyzed patients: 87 (40%) had intrinsic PEEP with a median of 1.1 [1.0-2.3] cmH2O at 5 cmH2O of PEEP. The intrinsic PEEP significantly decreased with higher PEEP (1.1 [1.0-2.3] vs 0.6 [0.0-1.0] cmH2O; p < 0.001). The applied tidal volume was significantly lower (480 [430-540] vs 520 [445-600] mL at 5 cmH2O of PEEP; 480 [430-540] vs 510 [430-590] mL at 15 cmH2O) in patients with intrinsic PEEP, while the respiratory rate was significantly higher (18 [15-20] vs 15 [13-19] bpm at 5 cmH2O of PEEP; 18 [15-20] vs 15 [13-19] bpm at 15 cmH2O). At both PEEP levels, the total airway resistance and compliance of the respiratory system were not different in patients with and without intrinsic PEEP. The total lung gas volume and lung recruitability were also not different between patients with and without intrinsic PEEP (respectively 961 [701-1535] vs 973 [659-1433] mL and 15 [0-32] % vs 22 [0-36] %). CONCLUSIONS: In sedated, paralyzed ARDS patients without a known obstructive disease, the amount of intrinsic PEEP during lung-protective ventilation is negligible and does not influence respiratory mechanical properties.


Assuntos
Fator Intrínseco , Respiração com Pressão Positiva/classificação , Síndrome do Desconforto Respiratório do Adulto/fisiopatologia , Idoso , Análise de Variância , Gasometria , Feminino , Humanos , Pulmão/fisiopatologia , Complacência Pulmonar/fisiologia , Masculino , Pessoa de Meia-Idade , Mecânica Respiratória , Estudos Retrospectivos , Volume de Ventilação Pulmonar/fisiologia
18.
Crit Care Resusc ; 21(4): 243-50, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31778630

RESUMO

BACKGROUND: Mechanical ventilation is mandatory in patients undergoing general anaesthesia for major surgery. Tidal volumes higher than 10 mL/kg of predicted body weight have been advocated for intraoperative ventilation, but recent evidence suggests that low tidal volumes may benefit surgical patients. To date, the impact of low tidal volume compared with conventional tidal volume during surgery has only been assessed in clinical trials that also combine different levels of positive end-expiratory pressure (PEEP) in each arm. We aimed to assess the impact of low tidal volume compared with conventional tidal volume during general anaesthesia for surgery on the incidence of postoperative respiratory complications in adult patients receiving moderate levels of PEEP. STUDY DESIGN AND METHODS: Single-centre, two-arm, randomised clinical trial. In total, 1240 adult patients older than 40 years scheduled for at least 2 hours of surgery under general anaesthesia and routinely monitored with an arterial line were included. Patients were ventilated intraoperatively with a moderate level of PEEP (5 cmH2O) and randomly assigned to tidal volume of 6 mL/kg predicted body weight (low tidal volume) or 10 mL/kg predicted body weight (conventional tidal volume in Australia). MAIN OUTCOME MEASURE: The primary outcome is the occurrence of postoperative respiratory complications, recorded as a composite endpoint of adverse respiratory events during the first 7 postoperative days. RESULTS AND CONCLUSIONS: This is the first well powered study comparing the effect of low tidal volume ventilation versus high tidal volume ventilation during surgery on the incidence of postoperative respiratory complications in adult patients receiving moderate levels of PEEP. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ACTRN12614000790640).


Assuntos
Anestesia Geral , Respiração com Pressão Positiva , Volume de Ventilação Pulmonar/efeitos dos fármacos , Adulto , Anestesia Geral/efeitos adversos , Austrália , Humanos , Respiração com Pressão Positiva/efeitos adversos , Ensaios Clínicos Controlados Aleatórios como Assunto , Respiração Artificial , Procedimentos Cirúrgicos Operatórios/efeitos adversos , Procedimentos Cirúrgicos Operatórios/métodos , Volume de Ventilação Pulmonar/fisiologia
19.
Intensive Care Med ; 45(10): 1401-1412, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31576435

RESUMO

PURPOSE: To evaluate whether a perioperative open-lung ventilation strategy prevents postoperative pulmonary complications after elective on-pump cardiac surgery. METHODS: In a pragmatic, randomized, multicenter, controlled trial, we assigned patients planned for on-pump cardiac surgery to either a conventional ventilation strategy with no ventilation during cardiopulmonary bypass (CPB) and lower perioperative positive end-expiratory pressure (PEEP) levels (2 cm H2O) or an open-lung ventilation strategy that included maintaining ventilation during CPB along with perioperative recruitment maneuvers and higher PEEP levels (8 cm H2O). All study patients were ventilated with low-tidal volumes before and after CPB (6 to 8 ml/kg of predicted body weight). The primary end point was a composite of pulmonary complications occurring within the first 7 postoperative days. RESULTS: Among 493 randomized patients, 488 completed the study (mean age, 65.7 years; 360 (73.7%) men; 230 (47.1%) underwent isolated valve surgery). Postoperative pulmonary complications occurred in 133 of 243 patients (54.7%) assigned to open-lung ventilation and in 145 of 245 patients (59.2%) assigned to conventional ventilation (p = 0.32). Open-lung ventilation did not significantly reduce the use of high-flow nasal oxygenotherapy (8.6% vs 9.4%; p = 0.77), non-invasive ventilation (13.2% vs 15.5%; p = 0.46) or new invasive mechanical ventilation (0.8% vs 2.4%, p = 0.28). Mean alive ICU-free days at postoperative day 7 was 4.4 ± 1.3 days in the open-lung group vs 4.3 ± 1.3 days in the conventional group (mean difference, 0.1 ± 0.1 day, p = 0.51). Extra-pulmonary complications and adverse events did not significantly differ between groups. CONCLUSIONS: A perioperative open-lung ventilation including ventilation during CPB does not reduce the incidence of postoperative pulmonary complications as compared with usual care. This finding does not support the use of such a strategy in patients undergoing on-pump cardiac surgery. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT02866578. https://clinicaltrials.gov/ct2/show/NCT02866578.


Assuntos
Procedimentos Cirúrgicos Cardíacos/normas , Complicações Pós-Operatórias/etiologia , Respiração Artificial/normas , Resultado do Tratamento , Idoso , Procedimentos Cirúrgicos Cardíacos/métodos , Procedimentos Cirúrgicos Cardíacos/estatística & dados numéricos , Oxigenação por Membrana Extracorpórea/métodos , Feminino , França/epidemiologia , Humanos , Pulmão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Respiração com Pressão Positiva/métodos , Respiração com Pressão Positiva/normas , Respiração com Pressão Positiva/estatística & dados numéricos , Complicações Pós-Operatórias/epidemiologia , Respiração Artificial/métodos , Respiração Artificial/estatística & dados numéricos , Volume de Ventilação Pulmonar/fisiologia
20.
Dan Med J ; 66(9)2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31495370

RESUMO

INTRODUCTION: An indication of the adequacy of the intra-vascular volume is of importance in critically ill patients. The status of the intravascular volume can be determined from a fluid challenge test. Most tests involve invasive monitoring. An exception is the capnographic measurement of changes in end-tidal (ET) CO2 after a fluid challenge. The method is appealing as it rests on solid physiological ground - the Fick principle and the Frank-Starling mechanism. Furthermore, it is non-invasive and convenient. We report the results of a systematic review of the merits of this method. METHODS: After a registration with PROSPERO, we searched MEDLINE, EMBASE, the Cochrane Library database and trial registers for studies on the diagnostic accuracy of changes in ET-CO2 in fluid responsiveness testing. Test sensitivity, specificity and area under the receiver operating charac-teristics curve (AUROC) were the primary outcome meas-ures. RESULTS: Seven papers met the inclusion criteria. The test was found to have a median sensitivity of 0.75 (range: 0.60-0.91) and a median specificity of 0.94 (range: 0.70-1.00). The median AUROC was 0.82 (range: 0.67-0.94); the diagnostic threshold was an increase in ET-CO2 of 2 mmHg/5%. CONCLUSIONS: Monitoring of ET-CO2 during fluid responsiveness testing provides good diagnostic value with few false negative tests and fewer false positive tests. The included studies have important methodological flaws. It must therefore be acknowledged that the diagnostic value of ET-CO2 monitoring found in the review is overrated and overrated to an unknown degree. Therefore, at the present state of affairs, implementation of the test cannot be considered evidence-based.


Assuntos
Dióxido de Carbono/sangue , Hidratação , Volume de Ventilação Pulmonar/fisiologia , Capnografia , Estado Terminal/terapia , Humanos , Estudos Observacionais como Assunto , Valor Preditivo dos Testes , Volume Sistólico/fisiologia , Resultado do Tratamento
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