El espacio muerto (VD/VT) como predictor de éxito en la extubación de pacientes postquirúrgicos de cirugía cardiovascular pediátrica / Dead space (VD/VT) as a predictor of successful extubation of patients after pediatric cardiovascular surgery

Introducción: La ventilación mecánica (VM) forma parte de la recuperación postoperatoria (PO) de niños con cirugía de cardiopatía congénita, pero su uso no está exento de riesgos. El fracaso de extubación (FE) se ha asociado con internaciones prolongadas, aumento de complicaciones y mortalidad. El objetivo es determinar un valor de Vd/Vt predictor de extubación exitosa (EE). Material y métodos: estudio de cohorte prospectivo y observacional realizado del 1 de Enero al 31 de Diciembre de 2016 en niños menores de 6 meses cursando PO de cirugía cardiovascular con circulación extracorpórea (CEC) con requerimientos de VM por más de 48 horas. En los mismo se analizó el éxito o fracaso de extubación. Previo a la extubación se registraron valores de mecánica respiratoria; Vd/Vt, CO2 espiratoria final, Vt/kg, etc. Otras variables registradas: edad, sexo, peso, requerimiento de VM antes de la cirugía, fisiología de ventrículo único, duración de VM, complicaciones, duración de la internación y mortalidad. Las variables continuas se describieron como mediana y rango intercuartilo (25-75) y se compararon con prueba de Wilcoxon, las categóricas como proporciones o porcentajes y se analizaron con chi2 . Se efectuó un análisis bivariado con diferentes puntos de corte de Vd/Vt pre extubación para realizar un análisis de sensibilidad del valor predictivo de EE. Resultados: Se evaluó Vd/Vt en 67 pacientes, tres se eliminaron por parálisis cordal (1) y parálisis del diafragma (2). Mediana de edad 23 días (10-55), peso 3.2 Kg (2.89- 3.88), días de VM 5 (3-7), días de internación 15 (2- 128), mortalidad 7,8%. Se extubaron con éxito 76% de los pacientes (50/64). Las características demográficas de los pacientes, la mecánica respiratoria, gases de sangre arterial y EtCO2 no tuvieron asociación significativa con EE. Un Vd/Vt pre extubación < 0,53 se asoció con EE. Conclusión: En la población estudiada un valor de Vd/Vt <0,53 se asoció con EE. Los pacientes con ventrículo único presentaron mayor FE.(AU)

Introduction: Mechanical ventilation (MV) is part of postoperative (PO) recovery of children with congenital heart disease surgery, but is not without risks. Extubation failure (EF) has been associated with prolonged hospital stays and increased complication and mortality rates. The goal is to determine the value of Vd/Vt as a predictor of successful extubation (SE). Material and methods: A prospective and observational cohort study was conducted from January 1 to December 31, 2016, in children under 6 months of age undergoing cardiovascular surgery with extracorporeal circulation (ECC) and requiring MV for more than 48 hours. Intubation success or failure was evaluated. Prior to extubation, respiratory mechanics values, such as Vd/Vt, final expiratory CO2, and Vt/kg, were recorded. Other variables, including age, sex, weight, VM requirement before surgery, single ventricle physiology, VM duration, complications, length of hospital stay, and mortality were also recorded. Continuous variables were described as median and interquartile range (25-75) and compared with the Wilcoxon test. Categorical variables were described as proportions or percentages and analyzed with chi2. Bivariate analysis was performed with different pre-extubation Vd/Vt cut-off points to analyze the sensitivity of the predictive value for SE. Results: Vd/Vt was evaluated in 67 patients; three were excluded because of vocal fold (1) and diaphragm paralysis (2). Median age was 23 days (10-55), weight 3.2 Kg (2.89- 3.88), days on MV 5 (3-7), length of hospital stay 15 (2- 128), and mortality rate 7.8%. Overall, 76% of patients (50/64) were successfully extubated. Patient demographics, respiratory mechanics, arterial blood gases, and EtCO2 were not significantly associated with SE. A pre-extubation Vd/ Vt < 0.53 was associated with SE. Conclusion: In this series of patients, a Vd/Vt value of <0.53 was associated with SE. EF was increased in patients with a single ventricle (AU)

Comparison of pressure-controlled volume-guaranteed ventilation and volume-controlled ventilation in obese patients during gynecologic laparoscopic surgery in the Trendelenburg position / Comparação entre ventilação garantida por volume controlado por pressão e ventilação controlada por volume em pacientes obesos durante cirurgia laparoscópica ginecológica na posição de Trendelenburg

Abstract Background and objectives: The aim of this study was to investigate the efficacy of the pressure-controlled, volume-guaranteed (PCV-VG) and volume-controlled ventilation (VCV) modes for maintaining adequate airway pressures, lung compliance and oxygenation in obese patients undergoing laparoscopic hysterectomy in the Trendelenburg position. Methods: Patients (104) who underwent laparoscopic gynecologic surgery with a body mass index between 30 and 40 kg.m-2 were randomized to receive either VCV or PCV-VG ventilation. The tidal volume was set at 8 mL.kg-1, with an inspired oxygen concentration of 0.4 with a Positive End-Expiratory Pressure (PEEP) of 5 mmHg. The peak inspiratory pressure, mean inspiratory pressure, plateau pressure, driving pressure, dynamic compliance, respiratory rate, exhaled tidal volume, etCO2, arterial blood gas analysis, heart rate and mean arterial pressure at 5 minutes after induction of anesthesia in the and at 5, 30 and 60 minutes, respectively, after pneumoperitoneum in the Trendelenburg position were recorded. Results: The PCV-VG group had significantly decreased peak inspiratory pressure, mean inspiratory pressur, plateau pressure, driving pressure and increased dynamic compliance compared to the VCV group. Mean PaO2 levels were significantly higher in the PCV-VG group than in the VCV group at every time point after pneumoperitoneum in the Trendelenburg position. Conclusions: The PCV-VG mode of ventilation limited the peak inspiratory pressure, decreased the driving pressure and increased the dynamic compliance compared to VCV in obese patients undergoing laparoscopic hysterectomy. PCV-VG may be a preferable modality to prevent barotrauma during laparoscopic surgeries in obese patients.

Resumo Justificativa e objetivos: O objetivo deste estudo foi investigar a eficácia dos modos de ventilação garantida por volume controlado por pressão (PCV-VG) e ventilação controlada por volume (VCV) para manter pressões adequadas nas vias aéreas, complacência pulmonar e oxigenação em pacientes obesos submetidos à histerectomia laparoscópica na posição de Trendelenburg. Métodos: Cento e quatro pacientes submetidos à cirurgia ginecológica laparoscópica, com índice de massa corporal entre 30 e 40 kg.m-2, foram randomizados para receber ventilação com VCV ou PCV-VG. O volume corrente foi fixado em 8 mL.kg-1, com uma concentração inspirada de oxigênio de 0,4 e pressão positiva expiratória final (PEEP) de 5 mmHg. Registramos os seguintes parâmetros: pressão de pico inspiratório, pressão inspiratória média, pressão de platô, driving pressure, complacência dinâmica, frequência respiratória, volume corrente expirado, etCO2, gasometria arterial, frequência cardíaca e pressão arterial média aos 5, 30 e 60 minutos, respectivamente, após o pneumoperitônio na posição de Trendelenburg. Resultados: O grupo PCV-VG apresentou uma redução significativa da pressão de pico inspiratório, pressão inspiratória média, pressão de platô, driving pressure e aumento da complacência dinâmica comparado ao grupo VCV. Os níveis médios de PaO2 foram significativamente maiores no grupo PCV-VG do que no grupo VCV em todos os momentos após o pneumoperitônio na posição de Trendelenburg. Conclusões: O modo de ventilação PCV-VG limitou a pressão de pico inspiratório, diminuiu a driving pressure e aumentou a complacência dinâmica, comparado ao VCV em pacientes obesas submetidas à histerectomia laparoscópica. O PCV-VG pode ser uma modalidade preferida para prevenir o barotrauma durante cirurgias laparoscópicas em pacientes obesos.

Respiratory evaluation through volumetric capnography among grade III obese and eutrophic individuals: a comparative study

ABSTRACT BACKGROUND: Excess trunk body fat in obese individuals influences respiratory physiological function. The aims of this study were to compare volumetric capnography findings (VCap) between severely obese patients and normal-weight subjects and to assess whether there is any association between neck circumference (NC), waist-hip ratio (WHR) and VCap among grade III obese individuals. DESIGN AND SETTING: Analytical observational case-matched cross-sectional study, University of Campinas. METHODS: This cross-sectional study compared VCap variables between 60 stage III obese patients and 60 normal-weight individuals. RESULTS: In comparison with the normal-weight group, obese patients presented higher alveolar minute volume (8.92 ± 4.94 versus 6.09 ± 2.2; P = < 0.0001), CO2 production (278 ± 91.0 versus 209 ± 60.23; P < 0.0001), expiratory tidal volume (807 ± 365 versus 624 ± 202; P = 0.005), CO2 production per breath (21.1 ± 9.7 versus 16.7 ± 6.16; P = 0.010) and peak expiratory flow (30.9 ± 11.9 versus 25.5 ± 9.13; P = 0.004). The end-expiratory CO2 (PetCO2) concentration (33.5 ± 4.88 versus 35.9 ± 3.79; P = 0.013) and the phase 3 slope were normalized according to expired tidal volume (0.02 ± 0.05 versus 0.03 ± 0.01; P = 0.049) were lower in the obese group. CONCLUSIONS: The greater the NC was, the larger were the alveolar minute volume, anatomical dead space, CO2 production per minute and per breath and expiratory volume; whereas the smaller were the phase 2 slope (P2Slp), phase 3 slope (P3Slp) and pressure drop in the mouth during inspiration.

Evaluation of respiratory dynamics by volumetric capnography during submaximal exercise protocol of six minutes on treadmill in cystic fibrosis patients / Avaliação da dinâmica respiratória por capnografia volumétrica durante o protocolo de exercício submáximo por seis minutos em esteira em pacientes com fibrose cística

Abstract Objectives: Volumetric capnography provides the standard CO2 elimination by the volume expired per respiratory cycle and is a measure to assess pulmonary involvement. Thus, the objective of this study was to evaluate the respiratory dynamics of healthy control subjects and those with cystic fibrosis in a submaximal exercise protocol for six minutes on the treadmill, using volumetric capnography parameters (slope 3 [Slp3], Slp3/tidal volume [Slp3/TV], and slope 2 [Slp2]). Methods: This was a cross-sectional study with 128 subjects (cystic fibrosis, 64 subjects; controls, 64 subjects]. Participants underwent volumetric capnography before, during, and after six minutes on the treadmill. Statistical analysis was performed using the Friedman, Mann-Whitney, and Kruskal-Wallis tests, considering age and sex. An alpha = 0.05 was considered. Results: Six minutes on the treadmill evaluation: in cystic fibrosis, volumetric capnography parameters were different before, during, and after six minutes on the treadmill; the same was observed for the controls, except for Slp2. Regarding age, an Slp3 difference was observed in cystic fibrosis patients regardless of age, at all moments, and in controls for age ≥ 12 years; a difference in Slp3/TV was observed in cystic fibrosis and controls, regardless of age; and an Slp2 difference in the cystic fibrosis, regardless of age. Regarding sex, Slp3 and Slp3/TV differences were observed in cystic fibrosis regardless of sex, and in controls in male participants; an Slp2 difference was observed in the cystic fibrosis and female participants. The analysis between groups (cystic fibrosis and controls) indicated that Slp3 and Slp3/TV has identified the CF, regardless of age and sex, while the Slp2 showed the CF considering age. Conclusions: Cystic fibrosis showed greater values of the parameters before, during, and after exercise, even when stratified by age and sex, which may indicate ventilation inhomogeneity in the peripheral pathways in the cystic fibrosis.

Resumo Objetivos: A capnografia volumétrica fornece o padrão de eliminação do CO2, pelo volume expirado por ciclo respiratório e avalia o comprometimento pulmonar. O objetivo do estudo foi avaliar a dinâmica respiratória de indivíduos controles saudáveis e em indivíduos com fibrose cística, em um protocolo de exercício submáximo por seis minutos em esteira, por parâmetros da capnografia volumétrica [slope 3(Slp3), Slp3/volume corrente (Slp3/TV) e slope 2(Slp2)]. Métodos: Estudo de corte transversal com 128 indivíduos [(fibrose cística) 64 indivíduos; (controles) 64 indivíduos]. Os participantes realizaram capnografia volumétrica antes, durante e após seis minutos em esteira. Análise estatística realizada pelos testes de Friedman, Mann-Whitney e Kruskal-Wallis, considerado a idade e o sexo. Alpha = 0,05. Resultados: Avaliação de seis minutos em esteira: na fibrose cística, os parâmetros da capnografia volumétrica foram diferentes antes, durante e após seis minutos em esteira, o mesmo ocorreu nos controles, exceto para o Slp2. Considerando a idade: (Slp3) diferença na FC, independentemente da idade, em todos os momentos e nos controles apenas para ≥ 12 anos; (Slp3/TV) diferença para fibrose cística e controles independentemente da idade; (Slp2) diferença apenas para o grupo fibrose cística, independentemente da idade. Considerando o sexo: (Slp3 e Slp3/TV) diferença para fibrose cística, independentemente do sexo, e controles apenas no sexo masculino; (Slp2) diferença para fibrose cística e sexo feminino. Análise entre grupos (fibrose cística versus controles): Slp3 e Slp3/TV identificou a fibrose cística, independentemente da idade e sexo, enquanto o Slp2 evidenciou a fibrose cística considerando a idade. Conclusão: A fibrose cística apresentou maiores valores dos parâmetros antes, durante e após exercício, inclusive quando se considerou idade e sexo, podendo indicar não homogeneidade da distribuição da ventilação nas vias periféricas.

Analysis of different levels of positive end-expiratory pressure during lung retrieval for transplantation: an experimental study

Atelectasis and inadequate oxygenation in lung donors is a common problem during the retrieval of these organs. Nevertheless, the use of high positive end-expiratory pressure (PEEP) is not habitual during procedures of lung retrieval. Twenty-one Sprague-Dawley male consanguineous rats were used in the study. The animals were divided into 3 groups according to the level of PEEP used: low (2 cmH2O), moderate (5 cmH2O), and high (10 cmH2O). Animals were ventilated with a tidal volume of 6 mL/kg. Before lung removal, the lungs were inspected for the presence of atelectasis. When atelectasis was detected, alveolar recruitment maneuvers were performed. Blood gasometric analysis was performed immediately. Finally, the lungs were retrieved, weighed, and submitted to histological analysis. The animals submitted to higher PEEP showed higher levels of oxygenation with the same tidal volumes PO2=262.14 (PEEP 2), 382.4 (PEEP 5), and 477.0 (PEEP 10). The occurrence of atelectasis was rare in animals with a PEEP of 10 cmH2O, which therefore required less frequent recruitment maneuvers (need for recruitment: PEEP 2=100%, PEEP 5 =100%, and PEEP 10=14.3%). There was no change in hemodynamic stability, occurrence of pulmonary edema, or other histological injuries with the use of high PEEP. The use of high PEEP (10 cmH2O) was feasible and probably a beneficial strategy for the prevention of atelectasis and the optimization of oxygenation during lung retrieval. Clinical studies should be performed to confirm this hypothesis.

Evaluation of volume responsiveness by pulse pressure variability and inferior vena cava dispensability index at different tidal volumes by mechanical ventilation

This study investigated the effects of tidal volume (TV) on the diagnostic value of pulse pressure variation (PPV) and the inferior vena cava dispensability index (IVC-DI) for volume responsiveness during mechanical ventilation. In patients undergoing elective surgery with mechanical ventilation, different TVs of 6, 9, and 12 mL/kg were given for two min. The left ventricular outflow tract velocity-time integral (VTI) was measured by transthoracic echocardiography. The IVC-DI was measured at sub-xyphoid transabdominal long axis. The PPV was measured via the radial artery and served as baseline. Index measurements were repeated after fluid challenge. VTI increased by more than 15% after fluid challenge, which was considered as volume responsive. Seventy-nine patients were enrolled, 38 of whom were considered positive volume responsive. Baseline data between the response group and the non-response group were similar. Receiver operating characteristic curve confirmed PPV accuracy in diagnosing an increase in volume responsiveness with increased TV. When TV was 12 mL/kg, the PPV area under the curve (AUC) was 0.93 and the threshold value was 15.5%. IVC-DI had the highest diagnostic accuracy at a TV of 9 mL/kg and an AUC of 0.79, with a threshold value of 15.3%. When TV increased to 12 mL/kg, the IVC-DI value decreased. When the TV was 9 and 12 mL/kg, PPV showed improved performance in diagnosing volume responsiveness than did IVC-DI. PPV diagnostic accuracy in mechanically ventilated patients was higher than IVC-DI. PPV accuracy in predicting volume responsiveness was increased by increasing TV.

Avaliação do tamanho do pulmão em cães: a capacidade inspiratória define o volume corrente / Sizing the lung in dogs: the inspiratory capacity defines the tidal volume

RESUMO Objetivo: Avaliar uma nova abordagem fisiológica para a determinação do volume corrente em ventilação mecânica, de acordo com a capacidade inspiratória, e determinar se isso resulta em medidas mecânicas e de troca gasosa adequadas em cães saudáveis e em estado crítico. Métodos: Incluíram-se, neste estudo, 24 animais para avaliar o volume corrente expresso como porcentagem da capacidade inspiratória. Para mensuração da capacidade inspiratória, o ventilador mecânico foi regulado como segue: modo controle de pressão, com 35cmH2O de pressão de inspiração e pressão expiratória final de zero, por 5 segundos. Subsequentemente, estudaram-se dez cães em condições clínicas críticas. Resultados: Cães saudáveis ventilados com volume corrente que correspondia a 17% da capacidade inspiratória demonstraram mecânica respiratória normal e apresentaram os valores previstos de PaCO2 mais frequentemente do que os animais nos demais grupos. A pressão no sistema respiratório e a pressão transpulmonar foram significantemente mais elevadas nos cães em condição crítica, porém em todos os casos, estiveram abaixo de 15cmH2O. Conclusões: O volume corrente calculado com base na capacidade inspiratória de cada animal comprovou ser uma ferramenta útil e simples para o estabelecimento dos parâmetros do ventilador. Convém também realizar abordagem semelhante em outras espécies, inclusive no ser humano, quando se consideram as potenciais limitações da titulação do volume corrente, com base no peso corpóreo ideal calculado.

ABSTRACT Objective: To evaluate a novel physiological approach for setting the tidal volume in mechanical ventilation according to inspiratory capacity, and to determine if it results in an appropriate mechanical and gas exchange measurements in healthy and critically ill dogs. Methods: Twenty healthy animals were included in the study to assess the tidal volume expressed as a percentage of inspiratory capacity. For inspiratory capacity measurement, the mechanical ventilator was set as follows: pressure control mode with 35cmH2O of inspired pressure and zero end-expiratory pressure for 5 seconds. Subsequently, the animals were randomized into four groups and ventilated with a tidal volume corresponding to the different percentages of inspiratory capacity. Subsequently, ten critically ill dogs were studied. Results: Healthy dogs ventilated with a tidal volume of 17% of the inspiratory capacity showed normal respiratory mechanics and presented expected PaCO2 values more frequently than the other groups. The respiratory system and transpulmonary driving pressure were significantly higher among the critically ill dogs but below 15 cmH2O in all cases. Conclusions: The tidal volume based on the inspiratory capacity of each animal has proven to be a useful and simple tool when setting ventilator parameters. A similar approach should also be evaluated in other species, including human beings, if we consider the potential limitations of tidal volume titration based on the calculated ideal body weight.

Influencia de la caja torácica en el monitoreo de la mecánica respiratoria en síndrome de distrés respiratorio agudo / Chest wall effect on the monitoring of respiratory mechanics in acute respiratory distress syndrome

RESUMEN La mecánica del sistema respiratorio depende de las características del pulmón, la caja torácica y su interacción. En pacientes con síndrome de distrés respiratorio agudo bajo ventilación mecánica el monitoreo de la presión meseta en la vía aérea es fundamental debido a su valor pronóstico y su capacidad de reflejar el estrés pulmonar. Sin embargo, su validez puede verse afectada por cambios en las características mecánicas de la caja torácica, y además, no otorga información para la correcta titulación de presión positiva al final de la espiración en función de restablecer el volumen pulmonar. La influencia que la caja torácica ejerce sobre la mecánica del sistema respiratorio en síndrome de distrés respiratorio agudo no ha sido completamente descripta y es probable que haya sido sobredimensionada pudiendo conducir a toma de decisiones erróneas. Ante la insuflación con presión positiva al final de la espiración, la carga impuesta por la caja torácica es despreciable. En condiciones dinámicas, desplazar esta estructura demanda un cambio de presión cuya magnitud se relaciona con sus características mecánicas, dicha carga se mantiene constante independientemente del volumen a partir del cual es insuflada. Por lo que cambios en la presión en la vía aérea reflejan modificaciones en las condiciones mecánicas del pulmón. El monitoreo avanzado podría reservarse para pacientes con incremento de la presión intra-abdominal en los que no pueda implementarse una estrategia de ventilación mecánica protectora. Las estimaciones de reclutamiento alveolar basadas en la mecánica del sistema respiratorio podrían ser reflejo del diferente comportamiento de la caja torácica a la insuflación y no verdadero reclutamiento alveolar.

ABSTRACT The respiratory system mechanics depend on the characteristics of the lung and chest wall and their interaction. In patients with acute respiratory distress syndrome under mechanical ventilation, the monitoring of airway plateau pressure is fundamental given its prognostic value and its capacity to assess pulmonary stress. However, its validity can be affected by changes in mechanical characteristics of the chest wall, and it provides no data to correctly titrate positive end-expiratory pressure by restoring lung volume. The chest wall effect on respiratory mechanics in acute respiratory distress syndrome has not been completely described, and it has likely been overestimated, which may lead to erroneous decision making. The load imposed by the chest wall is negligible when the respiratory system is insufflated with positive end-expiratory pressure. Under dynamic conditions, moving this structure demands a pressure change whose magnitude is related to its mechanical characteristics, and this load remains constant regardless of the volume from which it is insufflated. Thus, changes in airway pressure reflect changes in the lung mechanical conditions. Advanced monitoring could be reserved for patients with increased intra-abdominal pressure in whom a protective mechanical ventilation strategy cannot be implemented. The estimates of alveolar recruitment based on respiratory system mechanics could reflect differences in chest wall response to insufflation and not actual alveolar recruitment.

Aplicabilidade das variações respiratórias do volume sistólico e seus substitutos para predição da responsividade dinâmica a fluidos em pacientes críticos: uma revisão sistemática sobre a prevalência das condições requeridas / Applicability of respiratory variations in stroke volume and its surrogates for dynamic fluid responsiveness prediction in critically ill patients: a systematic review of the prevalence of required conditions

RESUMO Objetivo: Avaliar os dados publicados em relação à prevalência das condições requeridas para avaliação apropriada em pacientes críticos. Métodos: Foram realizadas buscas nas bases de dados MEDLINE, Scopus e Web of Science para identificar estudos que discutiam a prevalência de condições validadas para avaliação da responsividade a fluidos com uso de variações respiratórias do volume sistólico ou algum outro substituto em pacientes críticos adultos. O desfecho primário foi a prevalência de adequação para avaliação da responsividade. O objetivo secundário foi o tipo e a prevalência de pré-requisitos avaliados para definir a adequação. Resultados: Incluíram-se cinco estudos (14.804 pacientes). Observaram-se elevadas heterogeneidades do ponto de vista clínico e estatístico (I2 = 98,6%), o que impediu o agrupamento dos resultados em uma conclusão sumarizada significativa. A limitação mais frequentemente identificada foi a ausência de ventilação mecânica invasiva com volume corrente ≥ 8mL/kg. A adequação final para avaliação da responsividade a fluidos foi baixa (em quatro estudos, variou entre 1,9 e 8,3% e, em um estudo, foi de 42,4%). Conclusão: A aplicabilidade na prática diária de índices dinâmicos de responsividade da pré-carga que demandam interações cardiopulmonares pode ser limitada.

ABSTRACT Objective: The present systematic review searched for published data on the prevalence of required conditions for proper assessment in critically ill patients. Methods: The Medline, Scopus and Web of Science databases were searched to identify studies that evaluated the prevalence of validated conditions for the fluid responsiveness assessment using respiratory variations in the stroke volume or another surrogate in adult critically ill patients. The primary outcome was the suitability of the fluid responsiveness evaluation. The secondary objectives were the type and prevalence of pre-requisites evaluated to define the suitability. Results: Five studies were included (14,804 patients). High clinical and statistical heterogeneity was observed (I2 = 98.6%), which prevented us from pooling the results into a meaningful summary conclusion. The most frequent limitation identified is the absence of invasive mechanical ventilation with a tidal volume ≥ 8mL/kg. The final suitability for the fluid responsiveness assessment was low (in four studies, it varied between 1.9 to 8.3%, in one study, it was 42.4%). Conclusion: Applicability of the dynamic indices of preload responsiveness requiring heart-lung interactions might be limited in daily practice.

Inductive plethysmography potential as a surrogate for ventilatory measurements during rest and moderate physical exercise

Background: Portable respiratory inductive plethysmography (RIP) systems have been validated for ventilatory assessment during resting conditions and during incremental treadmill exercise. However, in clinical settings and during field-based exercise, intensity is usually constant and submaximal. A demonstration of the ability of RIP to detect respiratory measurements accurately during constant intensity conditions would promote and validate the routine use of portable RIP devices as an alternative to ergospirometry (ES), the current gold standard technique for ventilatory measures. Objective: To investigate the agreement between respiratory variables recorded by a portable RIP device and by ES during rest and constant intensity exercise. Method: Tidal volume (VT), respiratory rate (RR) and minute ventilation (VE) were concurrently acquired by portable RIP and ES in seven healthy male volunteers during standing rest position and constant intensity treadmill exercise. Results: Significant agreement was found between RIP and ES acquisitions during the standing rest position and constant intensity treadmill exercise for RR and during the standing rest position for VE. Conclusion: Our results suggest that portable RIP devices might represent a suitable alternative to ES during rest and during constant submaximal exercise.

Application of Mechanical Ventilation Weaning Predictors After Elective Cardiac Surgery

ABSTRACT OBJECTIVE: To test several weaning predictors as determinants of successful extubation after elective cardiac surgery. METHODS: The study was conducted at a tertiary hospital with 100 adult patients undergoing elective cardiac surgery from September to December 2014. We recorded demographic, clinical and surgical data, plus the following predictive indexes: static compliance (Cstat), tidal volume (Vt), respiratory rate (f), f/ Vt ratio, arterial partial oxygen pressure to fraction of inspired oxygen ratio (PaO2/FiO2), and the integrative weaning index (IWI). Extubation was considered successful when there was no need for reintubation within 48 hours. Sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), and negative likelihood ratio (LR-) were used to evaluate each index. RESULTS: The majority of the patients were male (60%), with mean age of 55.4±14.9 years and low risk of death (62%), according to InsCor. All of the patients were successfully extubated. Tobin Index presented the highest SE (0.99) and LR+ (0.99), followed by IWI (SE=0.98; LR+ =0.98). Other scores, such as SP, NPV and LR-were nullified due to lack of extubation failure. CONCLUSION: All of the weaning predictors tested in this sample of patients submitted to elective cardiac surgery showed high sensitivity, highlighting f/Vt and IWI.

Decreased lung compliance increases preload dynamic tests in a pediatric acute lung injury model / Una compliance pulmonar disminuida incrementa los test dinámicos de precarga en un modelo pediátrico de lesión pulmonar aguda

Background: Preload dynamic tests, pulse pressure variation (PPV) and stroke volume variation (SVV) have emerged as powerful tools to predict response to fluid administration. The influence of factors other than preload in dynamic preload test is currently poorly understood in pediatrics. The aim of our study was to assess the effect of tidal volume (V T) on PPV and SVV in the context of normal and reduced lung compliance in a piglet model. Material and method: Twenty large-white piglets (5.2 ± 0.4 kg) were anesthetized, paralyzed and monitored with pulse contour analysis. PPV and SVV were recorded during mechanical ventilation with a V T of 6 and 12 mL/kg (low and high V T, respectively), both before and after tracheal instillation of polysorbate 20. Results: Before acute lung injury (ALI) induction, modifications of V T did not significantly change PPV and SVV readings. After ALI, PPV and SVV were significantly greater during ventilation with a high V T compared to a low V T (PPV increased from 8.9 ± 1.2 to 12.4 ± 1.1%, and SVV from 8.5 ± 1.0 to 12.7 ± 1.2%, both P < 0.01). Conclusions: This study found that a high V T and reduced lung compliance due to ALI increase preload dynamic tests, with a greater influence of the latter. In subjects with ALI, lung compliance should be considered when interpreting the preload dynamic tests.

Introducción: Test dinámicos de precarga, variación de presión de pulso (PPV) y variación de volumen sistólico (SVV) han emergido como herramientas poderosas para predecir respuesta a la administración de fluidos. Actualmente la influencia de factores distintos a la precarga en la determinación de los test dinámicos de precarga es pobremente conocida en pediatría. Nuestro objetivo fue medir el efecto del volumen tidal (V T) sobre PPV y SVV en un contexto de compliance pulmonar normal y disminuida en un modelo porcino. Material y método: Veinte cerditos Large-White anestesiados y paralizados (5,2 ± 0,4 kg). PPV y SVV fueron medidos por análisis de contorno de pulso durante ventilación con V T de 6 y 12 mL/kg (V T bajo y alto, respectivamente), ambos previo y posterior a lesión pulmonar aguda (ALI) químicamente inducida con instilación traqueal de polisorbato 20. Resultados: Previo a inducción de ALI, PPV y SVV no tuvieron cambios significativos al modificar el V T. Sin embargo, después de ALI, PPV y SVV fueron significativamente mayores durante ventilación con V T alto, respecto a V T bajo (PPV aumentó de 8,9 ± 1,2 a 12,4 ± 1,1%, y SVV de 8,5 ± 1,0 a 12,7 ± 1,2%, ambos P < 0,01). Conclusiones: Este estudio encontró que un V T alto y una compliance pulmonar disminuida debido a ALI incrementan los test dinámicos de precarga, con una mayor influencia de esta última. En sujetos con ALI la compliance pulmonar debiera ser considerada al interpretar los test dinámicos de precarga.

Chronotropic incompetence in Chagas disease: effectiveness of blended sensor (volume/minute and accelerometer) / Competência cronotrópica em chagásicos: eficácia do duplo sensor (volume/minuto e acelerômetro)

AbstractIntroduction:Technological progress of pacemakers has allowed the association of two or more sensors in one heart rate system response. The accelerometer sensor measures the intensity of the activity; it has a relatively rapid response to the beginning of it, however, it may present insufficient response to less strenuous or of less impact exercise. The minute ventilation sensor changes the pacing rate in response to changes in respiratory frequency in relation to tidal volume, allowing responses to situations of emotional stress and low impact exercises.Objective:To evaluate the cardiorespiratory response of the accelerometer with respect to the blended sensor (BS=accelerometer sensor+minute ventilation sensor) to exercise in chagasic patients undergoing cardiopulmonary exercise test.Methods:This was a prospective, observational, randomized, cross-sectional study. Patients who met the inclusion criteria were selected. The maximum heart rate of the sensor was programmed by age (220-age). The results were analyzed through t test with paired samples (P<0.05).Results:Sample was comprised of 44 patients, with a mean age of 66±10.4 years, 58% were female, 54% as first implant, in 74% were functional class I and 26% were functional class II, left ventricular ejection fraction was 58±7. As for the cardiopulmonary test, maximum expected heart rate and VO2 were not achieved in both the accelerometer sensor and the blended sensor, however, metabolic equivalent in the blended sensor was higher than the expected, all data with P<0.001.Conclusion:Even though the maximal heart rate was not reached, the blended sensor provided a physiological electrical sequence when compared to the accelerometer sensor, providing better physical fitness test in cardiopulmonary hemodynamics and greater efficiency.

ResumoIntrodução:O progresso tecnológico dos marca passos permitiu a associação de dois ou mais sensores em um único sistema de resposta de frequência cardíaca. O sensor acelerômetro afere a intensidade da atividade, possui uma resposta relativamente rápida ao início da mesma, porém pode apresentar respostas insuficientes a exercícios físicos menos intensos ou de menor impacto. O sensor volume-minuto altera a taxa de estimulação cardíaca em resposta à variação da frequência respiratória quanto ao volume corrente, permitindo, assim, respostas a situações de estresse emocional e exercícios de baixo impacto.Objetivo:Avaliar a resposta cardiorrespiratória do acelerômetro em relação ao duplo sensor ao exercício em pacientes chagásicos submetidos ao teste ergoespirométrico.Métodos:Pesquisa prospectiva, observacional, randomizada e cruzada. Foram selecionados pacientes que preenchiam os critérios de inclusão. A frequência cardíaca máxima do sensor foi programada por idade (220-idade). Os resultados obtidos foram analisados pelo Teste T com amostras pareadas (P<0,05).Resultados:Amostra de 44 pacientes, com idade média de 66±10,4, com 58% do sexo feminino, 54% como primeiro implante, classe funcional I em 74% e II em 26%, fração de ejeção do ventrículo esquerdo de 58±7. Quanto ao ergoespirométrico, a frequência cardíaca máxima prevista e a VO2 máxima prevista não foram atingidas tanto no sensor acelerômetro quanto no sensor volume-minuto, contudo, o equivalente metabólico no sensor volume- minuto foi superior à prevista, todos os dados com P<0,001.Conclusão:Apesar da frequência cardíaca máxima não ter sido atingida, o duplo sensor proporcionou uma sequência elétrica mais fisiológica quando comparado ao sensor acelerômetro.

Preoperative therapy restores ventilatory parameters and reduces length of stay in patients undergoing myocardial revascularization / Fisioterapia pré-operatória restabelece parâmetros ventilatórios e reduz tempo de internação após revascularização do miocárdio

Introduction: The frequency of surgical procedures has increased steadily in recent decades, including the myocardial revascularization. Objectives: To demonstrate the importance of physiotherapy in the preoperative period of cardiac surgery in relation to the reduction of hospital stay, changes in lung volumes and respiratory muscle strength. Methods: We conducted a prospective study with patients undergoing myocardial revascularization, the Hospital das Clínicas da Universidade Estadual Paulista (UNESP)/Botucatu - SP. We evaluated 70 patients of both genders, aged between 40 and 75 years, subdivided into two groups: group I - 35 patients of both genders, who received a written protocol guidance, breathing exercises and respiratory muscle training in the preoperative period and group II - 35 patients of both genders, who received only orientation of the ward on the day of surgery. This study was approved by the Ethics Committee of UNESP / Botucatu - SP. Results: Maximal inspiratory pressure in third postoperative day and fifth postoperative day and significant difference between groups, being better for the intervention group. Expiratory pressure was significant in fifth postoperative day in the intervention group compared to controls. The difference of length of hospital stay in the postoperative was found between the groups with shorter hospital stay in the group receiving preoperative therapy. Conclusion: Physical therapy plays an important role in the preoperative period, so that individuals in the intervention group more readily restored the parameters evaluated before surgery, in addition, there was a decrease in the time of the postoperative hospital stay. Thus, it is thought the cost-effectiveness of a program of preoperative physiotherapy. .

Introdução: Procedimentos cirúrgicos aumentaram progressivamente nas últimas décadas, inclusive a revascularização do miocárdio(RM). Objetivos: Demonstrar a importância da fisioterapia no préoperatório de cirurgia cardíaca, em relação à redução do tempo de internação hospitalar, alteração de volumes pulmonares e força muscular respiratória. Métodos: Foi realizado estudo clínico prospectivo, com pacientes submetidos à revascularização do miocárdio, no Hospital das Clínicas da Universidade Estadual PaulistaUNESP / Botucatu - SP. Foram avaliados 70 pacientes de ambos os gêneros, com faixa etária entre 40 a 75 anos, randomizados por meio programa computadorizado em dois grupos: Grupo I - 35 pacientes de ambos os sexos, que receberam um protocolo de orientação por escrito, exercícios respiratórios e treinamento muscular respiratório no pré-operatório e Grupo II - 35 pacientes de ambos os gêneros, que receberam apenas orientação de rotina da enfermaria no dia da cirurgia. Trabalho foi aprovado pelo Comitê de Ética da Universidade Estadual PaulistaUNESP / Botucatu - SP. Resultados: A avaliação das pressões inspiratórias máximas evidenciou aumento significativo no terceiro dia pós-operatório e quinto dia pós-operatório para o grupo de intervenção e análise das pressões expiratórias máximas apresentou valores significativos apenas no quinto dia pós-operatório para o grupo intervenção em relação ao grupo controle, observando-se ainda que o grupo submetido ao protocolo de tratamento fisioterapêutico pré-operatório apresentou menor tempo de internação hospitalar. Conclusão: A fisioterapia ...

Prácticas de destete ventilatorio en las unidades de cuidado intensivo de la ciudad de Cali / Ventilatory weaning practices in intensive care units in the city of Cali

Objetivo: El destete temprano de la ventilación mecánica es uno de los objetivos primordiales en el manejo del paciente crítico. Existen diversas técnicas y parámetros de medida para realizarlo. El objetivo de esta investigación fue describir las prácticas del destete ventilatorio en unidades de cuidado intensivo adulto en la ciudad de Cali. Métodos: Una encuesta de 32 preguntas; algunas de múltiple escogencia, que evaluaron las prácticas del destete, fue distribuida entre los fisioterapeutas y terapeutas respiratorios que trabajaban en unidades de cuidado intensivo, para ser respondida de forma anónima. Resultados: La estrategia más frecuente para el registro de parámetros fue la combinación de presión positiva continua con presión de soporte (78%), con gran variabilidad en los niveles de presión, siendo el rango más frecuente de 6 a 8cmH2O. Los parámetros de destete más registrados fueron: el volumen corriente (92,6%), la frecuencia respiratoria (93,3%) y la saturación de oxígeno (90,4%). El tiempo de espera más frecuente para el registro de los parámetros fue >15 minutos (40%). Las medidas se realizaron preferentemente con el display del ventilador. Conclusion: Existe una gran variabilidad sobre los métodos y la medición de los parámetros de destete ventilatorio. El método más utilizado fue presión positiva continua en la vía aérea más presión de soporte y los parámetros de destete más usados fueron la medición del volumen corriente y la frecuencia respiratoria. .

Objective: Early weaning from mechanical ventilation is one of the primary goals in managing critically ill patients. There are various techniques and measurement parameters for such weaning. The objective of this study was to describe the practices of ventilatory weaning in adult intensive care units in the city of Cali. Methods: A survey of 32 questions (some multiple choice) evaluating weaning practices was distributed to physiotherapists and respiratory therapists working in intensive care units, to be answered anonymously. Results: The most common strategy for the parameter set was the combination of continuous positive airway pressure with pressure support (78%), with a large variability in pressure levels, the most common range being 6 to 8cmH2O. The most common weaning parameters were as follows: tidal volume (92.6%), respiratory rate (93.3%) and oxygen saturation (90.4%). The most common waiting time for registration of the parameters was >15 minutes (40%). The measurements were preferably obtained from the ventilator display. Conclusion: The methods and measurement parameters of ventilatory weaning vary greatly. The most commonly used method was continuous positive airway pressure with more pressure support and the most commonly used weaning parameters were the measured tidal volume and respiratory rate. .

Lesao pulmonar induzida pela ventilacao em recem-nascidos prematuros / Ventilator-induced lung injury in preterm infants

A necessidade de intubação e do uso de ventilação mecânica na prematuridade está relacionada à chamada lesão pulmonar induzida pela ventilação e à consequente displasia broncopulmonar. Busca-se a melhor compreensão dos mecanismos de lesão envolvendo resposta inflamatória mediada pelas citocinas para o desenvolvimento de novas estratégias protetoras. Pesquisou-se na base de dados PubMed, incluindo artigos relevantes, os unitermos "ventilator induced lung injury preterm", "continuous positive airway pressure", "preterm" e "bronchopulmonary dysplasia". Dados e informações significativas foram compilados em tópicos, com o objetivo de formar uma visão crítica e plena acerca da lesão induzida pela ventilação e de suas consequências ao prematuro. Foi revisado o papel das citocinas pró-inflamatórias como mediadores da lesão, especialmente interleucinas 6 e 8, e fator de necrose tumoral alfa. Foram apresentadas evidências em estudos com animais e também em humanos, mostrando que breves períodos de ventilação mecânica são suficientes para a liberação dessas interleucinas inflamatórias. Também foram revisadas outras formas de ventilação mecânica e de ventilação não invasiva, como alternativas protetoras aos modos convencionais. Concluiu-se que o uso de ventilação não invasiva, a intubação com administração precoce de surfactante e a extubação rápida para CPAP nasal, além de estratégias que regulam o volume corrente evitando o volutrauma (como a ventilação com volume garantido), são medidas protetoras da lesão pulmonar induzida pela ventilação mecânica no prematuro.

In preterm infants, the need for intubation and mechanical ventilation is associated with ventilator-induced lung injuries and subsequent bronchopulmonary dysplasia. The aim of the present review was to improve the understanding of the mechanisms of injury that involve cytokine-mediated inflammation to contribute to the development of new preventive strategies. Relevant articles were retrieved from the PubMed database using the search terms "ventilator-induced lung injury preterm", "continuous positive airway pressure", "preterm", and "bronchopulmonary dysplasia". The resulting data and other relevant information were divided into several topics to ensure a thorough, critical view of ventilation-induced lung injury and its consequences in preterm infants. The role of pro-inflammatory cytokines (particularly interleukins 6 and 8 and tumor necrosis factor alpha) as mediators of lung injury was assessed. Evidence from studies conducted with animals and human newborns is described. This evidence shows that brief periods of mechanical ventilation is sufficient to induce the release of pro-inflammatory cytokines. Other forms of mechanical and non-invasive ventilation were also analyzed as protective alternatives to conventional mechanical ventilation. It was concluded that non-invasive ventilation, intubation followed by early surfactant administration and quick extubation for nasal continuous positive airway pressure, and strategies that regulate tidal volume and avoid volutrauma (such as volume guarantee ventilation) protect against ventilator-induced lung injury in preterm infants.

Impacto da técnica de expiração lenta e prolongada na mecânica respiratória de lactentes sibilantes / Impact of the prolonged slow expiratory maneuver on respiratory mechanics in wheezing infants

OBJETIVO: Avaliar as alterações da mecânica respiratória e do volume corrente (VC) em lactentes sibilantes em ventilação espontânea após a realização da técnica de expiração lenta e prolongada (ELPr). MÉTODOS: Foram incluídos no estudo lactentes com história de sibilância recorrente e sem exacerbações nos 15 dias anteriores. Para a avaliação da função pulmonar, os lactentes foram sedados e posicionados em decúbito dorsal com máscara facial acoplada a um pneumotacógrafo. As variáveis da respiração corrente - VC e FR - e da mecânica respiratória - complacência do sistema respiratório (Csr), resistência (Rsr) e constante de tempo (psr) - foram mensuradas antes e após a realização de três sequências consecutivas de ELPr. RESULTADOS: Foram avaliados 18 lactentes, com média de idade de 32 ± 11 semanas. Houve um aumento significante no VC após ELPr (79,3 ± 15,6 mL vs. 85,7 ± 17,2 mL; p = 0,009), assim como uma redução na FR (40,6 ± 6,9 ciclos/min vs. 38,8 ± 0,9 ciclos/min; p = 0,042). Entretanto, não houve alterações significantes nos valores da mecânica respiratória (Csr: 11,0 ± 3,1 mL/cmH2O vs. 11,3 ± 2,7 mL/cmH2O; Rsr: 29,9 ± 6,2 cmH2O • mL-1 • s-1 vs. 30,8 ± 7,1 cmH2O • mL-1 • s-1; e psr: 0,32 ± 0,11 s vs. 0,34 ± 0,12 s; p > 0,05 para todos). CONCLUSÕES: Essa técnica de fisioterapia respiratória é capaz de induzir alterações significativas no VC e na FR de lactentes com sibilância recorrente, mesmo na ausência de exacerbações. A manutenção das variáveis da mecânica respiratória indica que a técnica é segura para ser aplicada nesse grupo de pacientes. Estudos com lactentes sintomáticos são necessários para quantificar os efeitos funcionais da técnica.

OBJECTIVE: To evaluate changes in respiratory mechanics and tidal volume (V T) in wheezing infants in spontaneous ventilation after performing the technique known as the prolonged, slow expiratory (PSE) maneuver. METHODS: We included infants with a history of recurrent wheezing and who had had no exacerbations in the previous 15 days. For the assessment of the pulmonary function, the infants were sedated and placed in the supine position, and a face mask was used and connected to a pneumotachograph. The variables of tidal breathing (V T and RR) as well as those of respiratory mechanics-respiratory system compliance (Crs), respiratory system resistance (Rrs), and the respiratory system time constant (prs)-were measured before and after three consecutive PSE maneuvers. RESULTS: We evaluated 18 infants. The mean age was 32 ± 11 weeks. After PSE, there was a significant increase in V T (79.3 ± 15.6 mL vs. 85.7 ± 17.2 mL; p = 0.009) and a significant decrease in RR (40.6 ± 6.9 breaths/min vs. 38.8 ± 0,9 breaths/min; p = 0.042). However, no significant differences were found in the variables of respiratory mechanics (Crs: 11.0 ± 3.1 mL/cmH2O vs. 11.3 ± 2.7 mL/cmH2O; Rrs: 29.9 ± 6.2 cmH2O • mL-1 • s-1 vs. 30.8 ± 7.1 cmH2O • mL-1 • s-1; and prs: 0.32 ± 0.11 s vs. 0.34 ±0.12 s; p > 0.05 for all). CONCLUSIONS: This respiratory therapy technique is able to induce significant changes in V T and RR in infants with recurrent wheezing, even in the absence of exacerbations. The fact that the variables related to respiratory mechanics remained unchanged indicates that the technique is safe to apply in this group of patients. Studies involving symptomatic infants are needed in order to quantify the functional effects of the technique.

Treinamento muscular melhora o volume corrente e a capacidade vital no pós-operatório de revascularização do miocárdio / Inspiratory muscle training improves tidal volume and vital capacity after CABG surgery

OBJETIVO: Avaliar a função pulmonar e força da musculatura respiratória no período pós-operatório e verificar o efeito do treinamento muscular inspiratório sobre as medidas de desempenho da musculatura respiratória em pacientes submetidos à revascularização do miocárdio. MÉTODOS: Estudo randomizado, incluindo 47 pacientes submetidos à revascularização do miocárdio com circulação extracorpórea. Os pacientes foram divididos em grupo controle (GC), 24 pacientes, e grupo estudo (GE) 23 pacientes, com idade média de 66,33 ± 10,20 anos e 61,83 ± 8,61 anos, respectivamente. O GE foi submetido à fisioterapia convencional e ao treinamento muscular inspiratório com threshold® IMT e o GC à fisioterapia convencional. Foram comparadas as pressões respiratórias máximas (Pimáx e Pemáx), volume corrente (VC), capacidade vital (CV) e pico de fluxo expiratório (Peak Flow) no pré-operatório (Pré-OP), 1º e 3º dias de pós-operatório (PO1) e (PO3). RESULTADOS: Observou-se redução significativa em todas as variáveis mensuradas no PO1, quando comparadas ao pré-operatório, nos dois grupos estudados, Pimáx (P<0,0001), Pemáx (P<0,0001), VC: GE (P<0,0004) e GC: (P< 0,0001) e CV GE: (P<0,0001) e GC: (P<0,0001) e peak flow (P<0,0001). No PO3, o GE apresentou em comparação ao GC, maior valor de CV, GE 1230,4 ± 477,86 ml vs. GC 919,17 ± 394,47 ml (P= 0,0222) e VC GE 608,09 ± 178,24 ml vs. GC 506,96 ± 168,31 ml (P=0,0490). CONCLUSÃO: Pacientes submetidos à cirurgia cardíaca sofrem redução da CV e da força muscular respiratória após a cirurgia. O treinamento muscular realizado foi eficaz em recuperar o VC e a CV no PO3, no grupo treinado.

OBJECTIVE: To evaluate lung function and respiratory muscle strength in the postoperative period and investigate the effect of inspiratory muscle training on measures of respiratory muscle performance in patients undergoing coronary artery bypass grafting. METHODS: A randomized study with 47 patients undergoing coronary artery bypass grafting with cardiopulmonary bypass. They were divided into study group (SG) 23 patients and control group (CG) 24 patients, mean age 61.83 ± 8.61 and 66.33 ± 10.20 years, EuroSCORE SG 0.71 ± 0.0018 and CG 0.76 ± 0.0029, respectively. The study group underwent physical therapy and inspiratory muscle training with threshold IMT® and CG underwent conventional physiotherapy. We compared the maximal respiratory pressures (MIP and MEP), tidal volume (TV), vital capacity (VC) and peak expiratory flow (peak flow) preoperatively (Pre-OP), 1st (PO1) and 3rd (PO3) postoperative day. RESULTS: There was a significant reduction in all variables measured on PO1 compared to preoperative values in both groups, MIP (P <0.0001), MEP (P <0.0001), TV SG (P <0.0004) and CG (P <0.0001) and VC SG (P <0.0001) and CG (P <0.0001) and peak flow (P <0.0001). At PO3, SG presented higher value of VC, GE 1230.4 ± 477.86 ml vs. GC 919.17 ± 394.47 ml (P=0.0222) and TV SG 608.09 ± 178.24 ml vs. CG 506.96 ± 168.31 ml (P= 0.0490). CONCLUSION: Patients undergoing cardiac surgery experience reduced ventilatory capacity and respiratory muscle strength after surgery. Muscle training was performed to retrieve TV and VC in the PO3, in the trained group.