RESUMEN
Mechanical ventilation is a life-support system used to ensure blood gas exchange and to assist the respiratory muscles in ventilating the lung during the acute phase of lung disease or following surgery. Positive-pressure mechanical ventilation differs considerably from normal physiologic breathing. This may lead to several negative physiological consequences, both on the lungs and on peripheral organs. First, hemodynamic changes can affect cardiovascular performance, cerebral perfusion pressure (CPP), and drainage of renal veins. Second, the negative effect of mechanical ventilation (compression stress) on the alveolar-capillary membrane and extracellular matrix may cause local and systemic inflammation, promoting lung and peripheral-organ injury. Third, intra-abdominal hypertension may further impair lung and peripheral-organ function during controlled and assisted ventilation. Mechanical ventilation should be optimized and personalized in each patient according to individual clinical needs. Multiple parameters must be adjusted appropriately to minimize ventilator-induced lung injury (VILI), including: inspiratory stress (the respiratory system inspiratory plateau pressure); dynamic strain (the ratio between tidal volume and the end-expiratory lung volume, or inspiratory capacity); static strain (the end-expiratory lung volume determined by positive end-expiratory pressure [PEEP]); driving pressure (the difference between the respiratory system inspiratory plateau pressure and PEEP); and mechanical power (the amount of mechanical energy imparted as a function of respiratory rate). More recently, patient self-inflicted lung injury (P-SILI) has been proposed as a potential mechanism promoting VILI. In the present chapter, we will discuss the physiological and pathophysiological consequences of mechanical ventilation and how to personalize mechanical ventilation parameters.
Asunto(s)
Respiración Artificial , Lesión Pulmonar Inducida por Ventilación Mecánica , Humanos , Pulmón , Respiración con Presión Positiva/efectos adversos , Respiración Artificial/efectos adversos , Volumen de Ventilación Pulmonar/fisiología , Lesión Pulmonar Inducida por Ventilación Mecánica/etiología , Lesión Pulmonar Inducida por Ventilación Mecánica/prevención & controlRESUMEN
BACKGROUND: Noninvasive ventilation (NIV) and High-flow nasal cannula (HFNC) are the main forms of treatment for acute respiratory failure. This study aimed to evaluate the effect, safety, and applicability of the NIV and HFNC in patients with acute hypoxemic respiratory failure (AHRF) caused by COVID-19. METHODS: In this retrospective study, we monitored the effect of NIV and HFNC on the SpO2 and respiratory rate before, during, and after treatment, length of stay, rates of endotracheal intubation, and mortality in patients with AHRF caused by COVID-19. Additionally, data regarding RT-PCR from physiotherapists who were directly involved in assisting COVID-19 patients and non-COVID-19. RESULTS: 62.2 % of patients were treated with HFNC. ROX index increased during and after NIV and HFNC treatment (P < 0.05). SpO2 increased during NIV treatment (P < 0.05), but was not maintained after treatment (P = 0.17). In addition, there was no difference in the respiratory rate during or after the NIV (P = 0.95) or HFNC (P = 0.60) treatment. The mortality rate was 35.7 % for NIV vs 21.4 % for HFNC (P = 0.45), while the total endotracheal intubation rate was 57.1 % for NIV vs 69.6 % for HFNC (P = 0.49). Two adverse events occurred during treatment with NIV and eight occurred during treatment with HFNC. There was no difference in the physiotherapists who tested positive for SARS-COV-2 directly involved in assisting COVID-19 patients and non-COVID-19 ones (P = 0.81). CONCLUSION: The application of NIV and HFNC in the critical care unit is feasible and associated with favorable outcomes. In addition, there was no increase in the infection of physiotherapists with SARS-CoV-2.
Asunto(s)
COVID-19/terapia , Cánula , Intubación Intratraqueal , Ventilación no Invasiva , Evaluación de Procesos y Resultados en Atención de Salud , Oxígeno/administración & dosificación , Respiración con Presión Positiva , Insuficiencia Respiratoria/terapia , Frecuencia Respiratoria/efectos de los fármacos , Enfermedad Aguda , Administración por Inhalación , Adulto , Anciano , Anciano de 80 o más Años , Brasil , COVID-19/complicaciones , COVID-19/mortalidad , Cánula/efectos adversos , Cánula/normas , Cánula/estadística & datos numéricos , Estudios de Factibilidad , Femenino , Humanos , Unidades de Cuidados Intensivos , Intubación Intratraqueal/estadística & datos numéricos , Tiempo de Internación/estadística & datos numéricos , Masculino , Persona de Mediana Edad , Ventilación no Invasiva/efectos adversos , Ventilación no Invasiva/métodos , Ventilación no Invasiva/normas , Ventilación no Invasiva/estadística & datos numéricos , Evaluación de Procesos y Resultados en Atención de Salud/estadística & datos numéricos , Fisioterapeutas , Respiración con Presión Positiva/efectos adversos , Respiración con Presión Positiva/normas , Respiración con Presión Positiva/estadística & datos numéricos , Insuficiencia Respiratoria/etiología , Insuficiencia Respiratoria/mortalidad , Estudios RetrospectivosRESUMEN
OBJECTIVE: Acute respiratory distress syndrome (ARDS) can be a devastating condition in children with cancer and alveolar recruitment maneuvers (ARMs) can theoretically improve oxygenation and survival. The study aimed to assess the feasibility of ARMs in critically ill children with cancer and ARDS. METHODS: We retrospectively analyzed 31 maneuvers in a series of 12 patients (median age of 8.9 years) with solid tumors (n=4), lymphomas (n=2), acute lymphoblastic leukemia (n=2), and acute myeloid leukemia (n=4). Patients received positive end-expiratory pressure from 25 up to 40 cmH20, with a delta pressure of 15 cmH2O for 60 seconds. We assessed blood gases pre- and post-maneuvers, as well as ventilation parameters, vital signs, hemoglobin, clinical signs of pulmonary bleeding, and radiological signs of barotrauma. Pre- and post-values were compared by the Wilcoxon test. RESULTS: Median platelet count was 53,200/mm3. Post-maneuvers, mean arterial pressure decreased more than 20% in two patients, and four needed an increase in vasoactive drugs. Hemoglobin levels remained stable 24 hours after ARMs, and signs of pneumothorax, pneumomediastinum, or subcutaneous emphysema were absent. Fraction of inspired oxygen decreased significantly after ARMs (FiO2; p=0.003). Oxygen partial pressure (PaO2)/FiO2 ratio increased significantly (p=0.0002), and the oxygenation index was reduced (p=0.01), but all these improvements were transient. Recruited patients' 28-day mortality was 58%. CONCLUSIONS: ARMs, although feasible in the context of thrombocytopenia, lead only to transient improvements, and can cause significant hemodynamic instability.
Asunto(s)
Neoplasias/complicaciones , Respiración con Presión Positiva/métodos , Síndrome de Dificultad Respiratoria/terapia , Análisis de los Gases de la Sangre , Niño , Estudios de Factibilidad , Accesibilidad a los Servicios de Salud , Humanos , Respiración con Presión Positiva/efectos adversos , Síndrome de Dificultad Respiratoria/etiología , Estudios RetrospectivosRESUMEN
ABSTRACT Objective: Acute respiratory distress syndrome (ARDS) can be a devastating condition in children with cancer and alveolar recruitment maneuvers (ARMs) can theoretically improve oxygenation and survival. The study aimed to assess the feasibility of ARMs in critically ill children with cancer and ARDS. Methods: We retrospectively analyzed 31 maneuvers in a series of 12 patients (median age of 8.9 years) with solid tumors (n=4), lymphomas (n=2), acute lymphoblastic leukemia (n=2), and acute myeloid leukemia (n=4). Patients received positive end-expiratory pressure from 25 up to 40 cmH20, with a delta pressure of 15 cmH2O for 60 seconds. We assessed blood gases pre- and post-maneuvers, as well as ventilation parameters, vital signs, hemoglobin, clinical signs of pulmonary bleeding, and radiological signs of barotrauma. Pre- and post-values were compared by the Wilcoxon test. Results: Median platelet count was 53,200/mm3. Post-maneuvers, mean arterial pressure decreased more than 20% in two patients, and four needed an increase in vasoactive drugs. Hemoglobin levels remained stable 24 hours after ARMs, and signs of pneumothorax, pneumomediastinum, or subcutaneous emphysema were absent. Fraction of inspired oxygen decreased significantly after ARMs (FiO2; p=0.003). Oxygen partial pressure (PaO2)/FiO2 ratio increased significantly (p=0.0002), and the oxygenation index was reduced (p=0.01), but all these improvements were transient. Recruited patients' 28-day mortality was 58%. Conclusions: ARMs, although feasible in the context of thrombocytopenia, lead only to transient improvements, and can cause significant hemodynamic instability.
RESUMO Objetivo: A síndrome do desconforto respiratório agudo (SDRA) pode ser uma condição devastadora em crianças com câncer e as manobras de recrutamento alveolar (MRA) podem melhorar a oxigenação e a sobrevida. O objetivo foi avaliar a viabilidade das MRA em crianças gravemente doentes com câncer e SDRA. Métodos: Analisamos retrospectivamente 31 manobras em 12 pacientes (idade mediana de 8,9 anos), com tumores sólidos (n=4), linfomas (n=2) e leucemias linfoide (n=2) e mieloide agudas (n=4). Os pacientes receberam pressão expiratória final positiva de 25 a 40 cmH20, com delta de pressão de 15 cmH2O por 60 segundos. Gasometrias foram analisadas pré e pós-manobras, bem como os parâmetros de ventilação, sinais vitais, hemoglobina, sinais clínicos de sangramento pulmonar e sinais radiológicos de barotrauma. Valores foram comparados com o teste de Wilcoxon. Resultados: A contagem mediana de plaquetas era de 53.200/mm3. Após as manobras, em dois pacientes, a pressão arterial média declinou mais de 20%, e quatro necessitaram de aumento de drogas vasoativas. A hemoglobina permaneceu estável 24 horas após a MRA, sem sinais de pneumotórax, pneumomediastino ou enfisema subcutâneo. Houve diminuição significativa nas frações inspiradas de oxigênio (FiO2; p=0,003). A relação pressão arterial de oxigênio (PaO2)/FiO2 aumentou (p=0,002), e o índice de oxigenação caiu (p=0,01), mas essas melhoras foram transitórias. A mortalidade em 28 dias foi de 58%. Conclusões: As MRA, embora viáveis no contexto da trombocitopenia, levam apenas a melhorias transitórias e podem causar instabilidade hemodinâmica significativa.
Asunto(s)
Humanos , Niño , Síndrome de Dificultad Respiratoria del Recién Nacido/terapia , Respiración con Presión Positiva/métodos , Neoplasias/complicaciones , Síndrome de Dificultad Respiratoria del Recién Nacido/etiología , Análisis de los Gases de la Sangre , Estudios de Factibilidad , Estudios Retrospectivos , Respiración con Presión Positiva/efectos adversos , Accesibilidad a los Servicios de SaludAsunto(s)
Anestesia General , Respiración con Presión Positiva/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Respiración con Presión Positiva/efectos adversos , Complicaciones Posoperatorias/etiología , Tamaño de la MuestraRESUMEN
BACKGROUND: Recruitment maneuver and positive end-expiratory pressure (PEEP) can be used to counteract intraoperative anesthesia-induced atelectasis. Variable ventilation can stabilize lung mechanics by avoiding the monotonic tidal volume and protect lung parenchyma as tidal recruitment is encompassed within the tidal volume variability. METHODS: Forty-nine (7 per group) male Wistar rats were anesthetized, paralyzed, and mechanically ventilated. A recruitment maneuver followed by stepwise decremental PEEP titration was performed while continuously estimating respiratory system mechanics using recursive least squares. After a new recruitment, animals were ventilated for 2 hours in volume-control with monotonic (VCV) or variable (VV) tidal volumes. PEEP was adjusted at a level corresponding to the minimum elastance or 2 cm H2O above or below this level. Lungs were harvested for histologic analysis (left lung) and cytokines measurement (right lung). Seven animals were euthanized before the first recruitment as controls. RESULTS: A time-dependent increase in respiratory system elastance was observed and significantly minimized by PEEP (P < .001). Variable ventilation attenuated the amount of concentrations of proinflammatory mediators in lung homogenate: neutrophil cytokine-induced neutrophil chemoattractant 1 (VV = 40 ± 5 and VCV = 57 ± 8 pg/mg; P < .0001) and interleukin-1ß (VV = 59 ± 25 and VCV = 261 ± 113 pg/mg; P < .0001). Variable ventilation was also associated with lower structural lung parenchyma damage. Significant reductions in air fraction at dorsal and caudal lung regions were observed in all ventilated animals (P < .001). CONCLUSIONS: Variable ventilation was more protective than conventional ventilation within the applied PEEP levels.
Asunto(s)
Anestésicos Disociativos/administración & dosificación , Neumonía/metabolismo , Neumonía/patología , Respiración con Presión Positiva/métodos , Mecánica Respiratoria/fisiología , Animales , Pulmón/metabolismo , Pulmón/patología , Masculino , Neumonía/etiología , Respiración con Presión Positiva/efectos adversos , Respiración con Presión Positiva/tendencias , Ratas , Ratas Wistar , Respiración Artificial/efectos adversos , Respiración Artificial/métodos , Respiración Artificial/tendencias , Volumen de Ventilación Pulmonar/fisiologíaRESUMEN
BACKGROUND: Mechanical ventilation (MV) may induce or aggravate lung injury through the production of cytokines, inflammatory infiltration of neutrophils, and changes in the permeability of the alveolar-capillary barrier. The use of positive end-expiratory pressure (PEEP) helps improve gas exchanges avoiding alveolar collapse at the end of expiration. The present study aimed to analyze inflammatory response and redox imbalance in lungs of rats submitted to MV with and without PEEP. METHODS: Eighteen Wistar rats were divided into three groups: control (CG), PEEP group (PG), and zero PEEP (ZEEP) group (ZG). PG and ZG were submitted to MV for 60 min with or without PEEP, respectively. Subsequently, the animals were euthanized, and blood, bronchoalveolar lavage fluid, and lungs were collected for analyses. RESULTS: The number of neutrophils was higher in PG compared with CG. Leucocyte and neutrophil influx in bronchoalveolar lavage fluid was higher in PG compared with CG. PG showed an increase in alveolar area compared with the other groups. There were increases in the levels of chemokines, CCL3 and CCL5, in PG compared with CG. There were increases in oxidation of lipids and proteins in PG compared with other groups. There were increases in the activity of superoxide dismutase and catalase in PG compared with CG and ZG. However, there was a decrease in the ratio of glutathione to glutathione disulfide in PG compared with other groups. CONCLUSIONS: MV with PEEP caused redox imbalance and inflammation in lungs of healthy rats.
Asunto(s)
Inflamación/etiología , Inflamación/metabolismo , Respiración con Presión Positiva/métodos , Respiración Artificial/métodos , Mecánica Respiratoria/fisiología , Animales , Masculino , Oxidación-Reducción , Respiración con Presión Positiva/efectos adversos , Ratas , Ratas Wistar , Respiración Artificial/efectos adversosRESUMEN
OBJECTIVE: Evaluate the accuracy of criteria for diagnosing pressure overassistance during pressure support ventilation. DESIGN: Prospective clinical study. SETTING: Medical-surgical ICU. PATIENTS: Adults under mechanical ventilation for 48 hours or more using pressure support ventilation and without any sedative for 6 hours or more. Overassistance was defined as the occurrence of work of breathing less than 0.3 J/L or 10% or more of ineffective inspiratory effort. Two alternative overassistance definitions were based on the occurrence of inspiratory esophageal pressure-time product of less than 50 cm H2O s/min or esophageal occlusion pressure of less than 1.5 cm H2O. INTERVENTIONS: The pressure support was set to 20 cm H2O and decreased in 3-cm H2O steps down to 2 cm H2O. MEASUREMENTS AND MAIN RESULTS: The following parameters were evaluated to diagnose overassistance: respiratory rate, tidal volume, minute ventilation, peripheral arterial oxygen saturation, rapid shallow breathing index, heart rate, mean arterial pressure, change in esophageal pressure during inspiration, and esophageal and airway occlusion pressure. In all definitions, the respiratory rate had the greatest accuracy for diagnosing overassistance (receiver operating characteristic area = 0.92; 0.91 and 0.76 for work of breathing, pressure-time product and esophageal occlusion pressure in definition, respectively) and always with a cutoff of 17 incursions per minute. In all definitions, a respiratory rate of less than or equal to 12 confirmed overassistance (100% specificity), whereas a respiratory rate of greater than or equal to 30 excluded overassistance (100% sensitivity). CONCLUSION: A respiratory rate of 17 breaths/min is the parameter with the greatest accuracy for diagnosing overassistance. Respiratory rates of less than or equal to 12 or greater than or equal to 30 are useful clinical references to confirm or exclude pressure support overassistance.
Asunto(s)
Respiración con Presión Positiva , Femenino , Humanos , Unidades de Cuidados Intensivos , Masculino , Persona de Mediana Edad , Oxígeno/sangre , Respiración con Presión Positiva/efectos adversos , Respiración con Presión Positiva/métodos , Estudios Prospectivos , Frecuencia Respiratoria , Volumen de Ventilación Pulmonar , Trabajo RespiratorioRESUMEN
Importance: The effects of recruitment maneuvers and positive end-expiratory pressure (PEEP) titration on clinical outcomes in patients with acute respiratory distress syndrome (ARDS) remain uncertain. Objective: To determine if lung recruitment associated with PEEP titration according to the best respiratory-system compliance decreases 28-day mortality of patients with moderate to severe ARDS compared with a conventional low-PEEP strategy. Design, Setting, and Participants: Multicenter, randomized trial conducted at 120 intensive care units (ICUs) from 9 countries from November 17, 2011, through April 25, 2017, enrolling adults with moderate to severe ARDS. Interventions: An experimental strategy with a lung recruitment maneuver and PEEP titration according to the best respiratory-system compliance (n = 501; experimental group) or a control strategy of low PEEP (n = 509). All patients received volume-assist control mode until weaning. Main Outcomes and Measures: The primary outcome was all-cause mortality until 28 days. Secondary outcomes were length of ICU and hospital stay; ventilator-free days through day 28; pneumothorax requiring drainage within 7 days; barotrauma within 7 days; and ICU, in-hospital, and 6-month mortality. Results: A total of 1010 patients (37.5% female; mean [SD] age, 50.9 [17.4] years) were enrolled and followed up. At 28 days, 277 of 501 patients (55.3%) in the experimental group and 251 of 509 patients (49.3%) in the control group had died (hazard ratio [HR], 1.20; 95% CI, 1.01 to 1.42; P = .041). Compared with the control group, the experimental group strategy increased 6-month mortality (65.3% vs 59.9%; HR, 1.18; 95% CI, 1.01 to 1.38; P = .04), decreased the number of mean ventilator-free days (5.3 vs 6.4; difference, -1.1; 95% CI, -2.1 to -0.1; P = .03), increased the risk of pneumothorax requiring drainage (3.2% vs 1.2%; difference, 2.0%; 95% CI, 0.0% to 4.0%; P = .03), and the risk of barotrauma (5.6% vs 1.6%; difference, 4.0%; 95% CI, 1.5% to 6.5%; P = .001). There were no significant differences in the length of ICU stay, length of hospital stay, ICU mortality, and in-hospital mortality. Conclusions and Relevance: In patients with moderate to severe ARDS, a strategy with lung recruitment and titrated PEEP compared with low PEEP increased 28-day all-cause mortality. These findings do not support the routine use of lung recruitment maneuver and PEEP titration in these patients. Trial Registration: clinicaltrials.gov Identifier: NCT01374022.
Asunto(s)
Respiración con Presión Positiva/métodos , Síndrome de Dificultad Respiratoria/terapia , Adulto , Anciano , Femenino , Humanos , Unidades de Cuidados Intensivos , Masculino , Persona de Mediana Edad , Neumotórax/etiología , Respiración con Presión Positiva/efectos adversos , Síndrome de Dificultad Respiratoria/mortalidad , Volumen de Ventilación Pulmonar , Insuficiencia del TratamientoRESUMEN
BACKGROUND: Patient-ventilator asynchrony is associated with a poorer outcome. The prevalence and severity of asynchrony during the early phase of weaning has never been specifically described. The authors' first aim was to evaluate the prognosis impact and the factors associated with asynchrony. Their second aim was to compare the prevalence of asynchrony according to two methods of detection: a visual inspection of signals and a computerized method integrating electromyographic activity of the diaphragm. METHODS: This was an ancillary study of a multicenter, randomized controlled trial comparing neurally adjusted ventilatory assist to pressure support ventilation. Asynchrony was quantified at 12, 24, 36, and 48 h after switching from controlled ventilation to a partial mode of ventilatory assistance according to the two methods. An asynchrony index greater than or equal to 10% defined severe asynchrony. RESULTS: A total of 103 patients ventilated for a median duration of 5 days (interquartile range, 3 to 9 days) were included. Whatever the method used for quantification, severe patient-ventilator asynchrony was not associated with an alteration of the outcome. No factor was associated with severe asynchrony. The prevalence of asynchrony was significantly lower when the quantification was based on flow and pressure than when it was based on the electromyographic activity of the diaphragm at 0.3 min (interquartile range, 0.2 to 0.8 min) and 4.7 min (interquartile range, 3.2 to 7.7 min; P < 0.0001), respectively. CONCLUSIONS: During the early phase of weaning in patients receiving a partial ventilatory mode, severe patient-ventilator asynchrony was not associated with adverse clinical outcome, although the prevalence of patient-ventilator asynchrony varies according to the definitions and methods used for detection.
Asunto(s)
Soporte Ventilatorio Interactivo/efectos adversos , Soporte Ventilatorio Interactivo/métodos , Respiración con Presión Positiva/efectos adversos , Respiración con Presión Positiva/métodos , Desconexión del Ventilador/efectos adversos , Desconexión del Ventilador/métodos , Anciano , Femenino , Francia/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Pronóstico , Respiración Artificial/efectos adversos , Respiración Artificial/métodos , Factores de RiesgoRESUMEN
INTRODUCTION: The obesity prevalence is increasing in surgical population. As the number of obese surgical patients increases, so does the demand for mechanical ventilation. Nevertheless, ventilatory strategies in this population are challenging, since obesity results in pathophysiological changes in respiratory function. Areas covered: We reviewed the impact of obesity on respiratory system and the effects of controlled invasive mechanical ventilation strategies in obese patients undergoing surgery. To date, there is no consensus regarding the optimal invasive mechanical ventilation strategy for obese surgical patients, and no evidence that possible intraoperative beneficial effects on oxygenation and mechanics translate into better postoperative pulmonary function or improved outcomes. Expert commentary: Before determining the ideal intraoperative ventilation strategy, it is important to analyze the pathophysiology and comorbidities of each obese patient. Protective ventilation with low tidal volume, driving pressure, energy, and mechanical power should be employed during surgery; however, further studies are required to clarify the most effective ventilation strategies, such as the optimal positive end-expiratory pressure and whether recruitment maneuvers minimize lung injury. In this context, an ongoing trial of intraoperative ventilation in obese patients (PROBESE) should help determine the mechanical ventilation strategy that best improves clinical outcome in patients with body mass index≥35kg/m2.
Asunto(s)
Obesidad/cirugía , Respiración Artificial/métodos , Respiración , Índice de Masa Corporal , Humanos , Obesidad/fisiopatología , Respiración con Presión Positiva/efectos adversos , Respiración con Presión Positiva/métodos , Respiración Artificial/efectos adversos , Volumen de Ventilación Pulmonar/fisiologíaRESUMEN
BACKGROUND: Mask ventilation is routinely performed during anesthesia. Under some circumstances, it might be difficult to perform, such as in edentulous patients, due to inadequate mask seal. We developed a new device called NIPARA and studied its use For ventilation optimization in edentulous patients. METHODS: This randomized controlled trial included edentulous adults who had no other predictors of difficult airway, scheduled to undergo general anesthesia. Patients were assigned either to the NIPARA device group or to the control group (oral airway only). The primary outcomes were peak inspiratory pressure and tidal volume values of the first 14 breaths. The secondary outcome was the incidence of complications. RESULTS: Data from 37 patients were collected during a one-year period (twenty in the NIPARA device group and 17 in the control group). The difference in mean PIP was not statistically significant. The tidal volume was 1.5 times greater in the NIPARA group than in the control group. One patient from the intervention group had minimal oral trauma. CONCLUSION: In the administration of face mask ventilation, NIPARA is an effective device that significantly improves the tidal volume administered in edentulous patients.
Asunto(s)
Arcada Edéntula , Máscaras , Respiración con Presión Positiva/instrumentación , Anestesia/métodos , Humanos , Ápice del Flujo Espiratorio , Respiración con Presión Positiva/efectos adversos , Respiración con Presión Positiva/normas , Volumen de Ventilación PulmonarRESUMEN
BACKGROUND: Pressure support ventilation (PSV) is often associated with patient-ventilator asynchrony. Proportional assist ventilation (PAV) offers inspiratory assistance proportional to patient effort, minimizing patient-ventilator asynchrony. The objective of this study was to evaluate the influence of respiratory mechanics and patient effort on patient-ventilator asynchrony during PSV and PAV plus (PAV+). METHODS: We used a mechanical lung simulator and studied 3 respiratory mechanics profiles (normal, obstructive, and restrictive), with variations in the duration of inspiratory effort: 0.5, 1.0, 1.5, and 2.0 s. The Auto-Trak system was studied in ventilators when available. Outcome measures included inspiratory trigger delay, expiratory trigger asynchrony, and tidal volume (VT). RESULTS: Inspiratory trigger delay was greater in the obstructive respiratory mechanics profile and greatest with a effort of 2.0 s (160 ms); cycling asynchrony, particularly delayed cycling, was common in the obstructive profile, whereas the restrictive profile was associated with premature cycling. In comparison with PSV, PAV+ improved patient-ventilator synchrony, with a shorter triggering delay (28 ms vs 116 ms) and no cycling asynchrony in the restrictive profile. VT was lower with PAV+ than with PSV (630 mL vs 837 mL), as it was with the single-limb circuit ventilator (570 mL vs 837 mL). PAV+ mode was associated with longer cycling delays than were the other ventilation modes, especially for the obstructive profile and higher effort values. Auto-Trak eliminated automatic triggering. CONCLUSIONS: Mechanical ventilation asynchrony was influenced by effort, respiratory mechanics, ventilator type, and ventilation mode. In PSV mode, delayed cycling was associated with shorter effort in obstructive respiratory mechanics profiles, whereas premature cycling was more common with longer effort and a restrictive profile. PAV+ prevented premature cycling but not delayed cycling, especially in obstructive respiratory mechanics profiles, and it was associated with a lower VT.
Asunto(s)
Soporte Ventilatorio Interactivo/efectos adversos , Respiración con Presión Positiva/efectos adversos , Mecánica Respiratoria/fisiología , Ventiladores Mecánicos/efectos adversos , Humanos , Inhalación , Soporte Ventilatorio Interactivo/instrumentación , Soporte Ventilatorio Interactivo/métodos , Modelos Anatómicos , Respiración con Presión Positiva/instrumentación , Respiración con Presión Positiva/métodos , Volumen de Ventilación Pulmonar , Factores de TiempoRESUMEN
BACKGROUND: Protective mechanical ventilation strategies using low tidal volume or high levels of positive end-expiratory pressure (PEEP) improve outcomes for patients who have had surgery. The role of the driving pressure, which is the difference between the plateau pressure and the level of positive end-expiratory pressure is not known. We investigated the association of tidal volume, the level of PEEP, and driving pressure during intraoperative ventilation with the development of postoperative pulmonary complications. METHODS: We did a meta-analysis of individual patient data from randomised controlled trials of protective ventilation during general anesthaesia for surgery published up to July 30, 2015. The main outcome was development of postoperative pulmonary complications (postoperative lung injury, pulmonary infection, or barotrauma). FINDINGS: We included data from 17 randomised controlled trials, including 2250 patients. Multivariate analysis suggested that driving pressure was associated with the development of postoperative pulmonary complications (odds ratio [OR] for one unit increase of driving pressure 1·16, 95% CI 1·13-1·19; p<0·0001), whereas we detected no association for tidal volume (1·05, 0·98-1·13; p=0·179). PEEP did not have a large enough effect in univariate analysis to warrant inclusion in the multivariate analysis. In a mediator analysis, driving pressure was the only significant mediator of the effects of protective ventilation on development of pulmonary complications (p=0·027). In two studies that compared low with high PEEP during low tidal volume ventilation, an increase in the level of PEEP that resulted in an increase in driving pressure was associated with more postoperative pulmonary complications (OR 3·11, 95% CI 1·39-6·96; p=0·006). INTERPRETATION: In patients having surgery, intraoperative high driving pressure and changes in the level of PEEP that result in an increase of driving pressure are associated with more postoperative pulmonary complications. However, a randomised controlled trial comparing ventilation based on driving pressure with usual care is needed to confirm these findings. FUNDING: None.
Asunto(s)
Anestesia General/efectos adversos , Enfermedades Pulmonares/etiología , Respiración con Presión Positiva/efectos adversos , Complicaciones Posoperatorias/etiología , Adulto , Anciano , Anestesia General/métodos , Femenino , Humanos , Periodo Intraoperatorio , Masculino , Persona de Mediana Edad , Respiración con Presión Positiva/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto , Volumen de Ventilación PulmonarRESUMEN
INTRODUCTION: The benefits of prone position ventilation are well demonstrated in the severe forms of acute respiratory distress syndrome, but not in the milder forms. We investigated the effects of prone position on arterial blood gases, lung inflammation, and histology in an experimental mild acute lung injury (ALI) model. METHODS: ALI was induced in Wistar rats by intraperitoneal Escherichia coli lipopolysaccharide (LPS, 5 mg/kg). After 24 h, the animals with PaO2/FIO2 between 200 and 300 mmHg were randomized into 2 groups: prone position (n = 6) and supine position (n = 6). Both groups were compared with a control group (n = 5) that was ventilated in the supine position. All of the groups were ventilated for 1 h with volume-controlled ventilation mode (tidal volume = 6 ml/kg, respiratory rate = 80 breaths/min, positive end-expiratory pressure = 5 cmH2O, inspired oxygen fraction = 1) RESULTS: Significantly higher lung injury scores were observed in the LPS-supine group compared to the LPS-prone and control groups (0.32 ± 0.03; 0.17 ± 0.03 and 0.13 ± 0.04, respectively) (p < 0.001), mainly due to a higher neutrophil infiltration level in the interstitial space and more proteinaceous debris that filled the airspaces. Similar differences were observed when the gravity-dependent lung regions and non-dependent lung regions were analyzed separately (p < 0.05). The BAL neutrophil content was also higher in the LPS-supine group compared to the LPS-prone and control groups (p < 0.05). There were no significant differences in the wet/dry ratio and gas exchange levels. CONCLUSIONS: In this experimental extrapulmonary mild ALI model, prone position ventilation for 1 h, when compared with supine position ventilation, was associated with lower lung inflammation and injury.
Asunto(s)
Lesión Pulmonar Aguda/prevención & control , Lipopolisacáridos , Pulmón/patología , Neumonía/prevención & control , Respiración con Presión Positiva/métodos , Posición Prona , Lesión Pulmonar Inducida por Ventilación Mecánica/prevención & control , Lesión Pulmonar Aguda/sangre , Lesión Pulmonar Aguda/inducido químicamente , Lesión Pulmonar Aguda/patología , Animales , Modelos Animales de Enfermedad , Inyecciones Intraperitoneales , Pulmón/fisiopatología , Masculino , Infiltración Neutrófila , Neumonía/sangre , Neumonía/inducido químicamente , Neumonía/patología , Respiración con Presión Positiva/efectos adversos , Ratas Wistar , Frecuencia Respiratoria , Posición Supina , Volumen de Ventilación Pulmonar , Lesión Pulmonar Inducida por Ventilación Mecánica/sangre , Lesión Pulmonar Inducida por Ventilación Mecánica/inducido químicamente , Lesión Pulmonar Inducida por Ventilación Mecánica/patologíaRESUMEN
The study's objective was to evaluate the association between neonatal ventilatory support and the subsequent occurrence of respiratory diseases in children up to six years of age. This was a population-based birth cohort study. The main exposure was ventilatory support at birth, defined as the use of nasal continuous positive airway pressure (NCPAP) and/or mechanical ventilation (MV) for more than three hours from the time of hospitalization at birth until the first 28 days of life. Outcomes were: chest wheezing in the twelve months prior to the follow-up interview, medical diagnosis of asthma any time in the child´s life, and occurrence of pneumonia up to six years of age. Crude and adjusted analyses for potential confounding variables were performed using Poisson regression. 3,624 children were analyzed. NCPAP plus MV or MV alone was associated with higher frequency of medical diagnosis of asthma, even after adjusting for maternal and child characteristics (PR = 2.24; 95%CI: 1.27-3.99). The results highlight medium-term respiratory complications associated with neonatal ventilatory support.
Asunto(s)
Enfermedades del Prematuro/etiología , Soporte Ventilatorio Interactivo/efectos adversos , Respiración con Presión Positiva/efectos adversos , Trastornos Respiratorios/etiología , Brasil , Niño , Preescolar , Estudios de Cohortes , Femenino , Edad Gestacional , Humanos , Lactante , Recién Nacido de Bajo Peso , Recién Nacido , Recien Nacido Prematuro , Enfermedades del Prematuro/terapia , Unidades de Cuidado Intensivo Neonatal , Masculino , Trastornos Respiratorios/clasificación , Trastornos Respiratorios/terapia , Factores SocioeconómicosRESUMEN
O objetivo do estudo foi avaliar a associação entre suporte ventilatório no período neonatal e doenças respiratórias até os seis anos de idade. Estudo de coorte de nascimentos de base populacional. A exposição principal foi o suporte ventilatório ao nascimento, definido como o uso de pressão contínua positiva nasal (CPAPn) e/ou ventilação mecânica (VM) por mais de três horas, desde o momento da hospitalização ao nascimento até os 28 dias. Os desfechos foram chiado no peito nos últimos 12 meses, diagnóstico médico de asma alguma vez na vida e episódio de pneumonia ocorrido até os seis anos de idade. Foram realizadas análises brutas e ajustadas para potenciais variáveis de confusão, usando regressão de Poisson. Foram analisadas 3.624 crianças. O uso de CPAPn e VM ou unicamente VM esteve associado com maior frequência de diagnóstico médico de asma, mesmo após ajuste para características maternas e das crianças (RP = 2,24; IC95%: 1,27-3,99). Os resultados do presente estudo alertam para as complicações respiratórias, em médio prazo, decorrentes do suporte ventilatório realizado no período neonatal.
El objetivo del estudio fue evaluar la asociación entre el soporte ventilatorio durante el período neonatal y las enfermedades respiratorias durante los seis primeros años de vida. Se trata de un estudio de cohorte de nacimiento con base poblacional. La exposición principal, soporte ventilatorio al nacimiento, fue definida como el uso de presión positiva nasal (CPAPn) y/o ventilación mecánica (VM) durante más de tres horas, desde la hospitalización al nacimiento, hasta los 28 días de vida. Los resultados analizados fueron: broncoespasmo en los últimos doce meses, diagnóstico médico de asma - realizado alguna vez en la vida- y episodio de neumonía ocurrido hasta los seis años de edad. Se realizaron análisis brutos y ajustados para potenciales variables de confusión, usando la regresión de Poisson. Fueron estudiados 3.624 niños. El uso de soporte ventilatorio estuvo asociado con una mayor frecuencia de diagnóstico médico de asma, incluso tras ajustar las características maternas y de los niños (RP = 2,24; IC95%: 1,27-3,99). Los resultados alertan sobre las complicaciones respiratorias a medio plazo tras el soporte ventilatorio realizado en el período neonatal.
The study's objective was to evaluate the association between neonatal ventilatory support and the subsequent occurrence of respiratory diseases in children up to six years of age. This was a population-based birth cohort study. The main exposure was ventilatory support at birth, defined as the use of nasal continuous positive airway pressure (NCPAP) and/or mechanical ventilation (MV) for more than three hours from the time of hospitalization at birth until the first 28 days of life. Outcomes were: chest wheezing in the twelve months prior to the follow-up interview, medical diagnosis of asthma any time in the child´s life, and occurrence of pneumonia up to six years of age. Crude and adjusted analyses for potential confounding variables were performed using Poisson regression. 3,624 children were analyzed. NCPAP plus MV or MV alone was associated with higher frequency of medical diagnosis of asthma, even after adjusting for maternal and child characteristics (PR = 2.24; 95%CI: 1.27-3.99). The results highlight medium-term respiratory complications associated with neonatal ventilatory support.
Asunto(s)
Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Enfermedades del Prematuro/etiología , Soporte Ventilatorio Interactivo/efectos adversos , Respiración con Presión Positiva/efectos adversos , Trastornos Respiratorios/etiología , Brasil , Estudios de Cohortes , Edad Gestacional , Recién Nacido de Bajo Peso , Recien Nacido Prematuro , Unidades de Cuidado Intensivo Neonatal , Enfermedades del Prematuro/terapia , Trastornos Respiratorios/clasificación , Trastornos Respiratorios/terapia , Factores SocioeconómicosRESUMEN
BACKGROUND: The role of positive end-expiratory pressure in mechanical ventilation during general anaesthesia for surgery remains uncertain. Levels of pressure higher than 0 cm H2O might protect against postoperative pulmonary complications but could also cause intraoperative circulatory depression and lung injury from overdistension. We tested the hypothesis that a high level of positive end-expiratory pressure with recruitment manoeuvres protects against postoperative pulmonary complications in patients at risk of complications who are receiving mechanical ventilation with low tidal volumes during general anaesthesia for open abdominal surgery. METHODS: In this randomised controlled trial at 30 centres in Europe and North and South America, we recruited 900 patients at risk for postoperative pulmonary complications who were planned for open abdominal surgery under general anaesthesia and ventilation at tidal volumes of 8 mL/kg. We randomly allocated patients to either a high level of positive end-expiratory pressure (12 cm H2O) with recruitment manoeuvres (higher PEEP group) or a low level of pressure (≤2 cm H2O) without recruitment manoeuvres (lower PEEP group). We used a centralised computer-generated randomisation system. Patients and outcome assessors were masked to the intervention. Primary endpoint was a composite of postoperative pulmonary complications by postoperative day 5. Analysis was by intention-to-treat. The study is registered at Controlled-Trials.com, number ISRCTN70332574. FINDINGS: From February, 2011, to January, 2013, 447 patients were randomly allocated to the higher PEEP group and 453 to the lower PEEP group. Six patients were excluded from the analysis, four because they withdrew consent and two for violation of inclusion criteria. Median levels of positive end-expiratory pressure were 12 cm H2O (IQR 12-12) in the higher PEEP group and 2 cm H2O (0-2) in the lower PEEP group. Postoperative pulmonary complications were reported in 174 (40%) of 445 patients in the higher PEEP group versus 172 (39%) of 449 patients in the lower PEEP group (relative risk 1·01; 95% CI 0·86-1·20; p=0·86). Compared with patients in the lower PEEP group, those in the higher PEEP group developed intraoperative hypotension and needed more vasoactive drugs. INTERPRETATION: A strategy with a high level of positive end-expiratory pressure and recruitment manoeuvres during open abdominal surgery does not protect against postoperative pulmonary complications. An intraoperative protective ventilation strategy should include a low tidal volume and low positive end-expiratory pressure, without recruitment manoeuvres. FUNDING: Academic Medical Center (Amsterdam, Netherlands), European Society of Anaesthesiology.
Asunto(s)
Abdomen/cirugía , Anestesia General/métodos , Enfermedades Pulmonares/prevención & control , Respiración con Presión Positiva/métodos , Complicaciones Posoperatorias/prevención & control , Procedimientos Quirúrgicos Operativos/métodos , Anciano , Anestesia General/efectos adversos , Método Doble Ciego , Europa (Continente) , Femenino , Humanos , Enfermedades Pulmonares/etiología , Masculino , Persona de Mediana Edad , América del Norte , Respiración con Presión Positiva/efectos adversos , Complicaciones Posoperatorias/etiología , Factores de Riesgo , América del Sur , Procedimientos Quirúrgicos Operativos/efectos adversos , Volumen de Ventilación Pulmonar , Resultado del TratamientoRESUMEN
OBJECTIVES: To test the tolerance and safety of an alveolar recruitment manoeuvre performed in the immediate postoperative period of corrective open heart surgery in children with congenital heart disease associated with excessive pulmonary blood flow and pulmonary arterial hypertension due to left-to-right shunt. METHODS: Ten infants aged 1-24 months with congenital heart disease associated with excessive pulmonary blood flow and pulmonary artery hypertension (mean pulmonary artery pressure ≥ 25 mmHg) were evaluated. The alveolar recruitment manoeuvre was performed in the operating theatre right after skin closure, and consisted of three successive stages of 30 s each, intercalated by a 1-min interval of baseline ventilation. Positive end-expiratory pressure was set to 10 cmH2O in the first stage and to 15 cmH2O in the two last ones, while the peak inspiratory pressure was kept at to 30 cmH2O in the first stage and at 35 cmH2O in the latter ones. Haemodynamic and respiratory variables were recorded. RESULTS: There was a slight but significant increase in mean pulmonary artery pressure from baseline to Stage 3 (P = 0.0009), as well as between Stages 1 and 2 (P = 0.0001), and 1 and 3 (P = 0.001), with no significant difference between Stages 2 and 3 (P = 0.06). Upon completion of the third stage, there were significant increases in arterial haemoglobin saturation as measured by pulse oximetry (P = 0.0009), arterial blood partial pressure of oxygen (P = 0.04), venous blood oxygen saturation of haemoglobin (P = 0.03) and arterial oxygen partial pressure over inspired oxygen fraction ratio (P = 0.04). A significant reduction in arterial blood partial pressure of carbon dioxide (P = 0.01) and in end tidal carbon dioxide also occurred (P = 0.009). The manoeuvre was well tolerated and besides a slight and transitory elevation in mean pulmonary artery, no other adverse haemodynamic or ventilatory effect was elicited. CONCLUSIONS: The alveolar recruitment manoeuvre seemed to be safe and well tolerated immediately after open heart surgery in infants liable to pulmonary hypertensive crises.