Effects of Different Tidal Volumes and PEEPs on Cardiac Output in Pigs Measured by Pulmonary Artery Catheter， Pulse Contour Analysis and Transpulmonary Thermodilution / 中山大学学报(医学科学版)

ObjectiveTo compare the effects of different tidal volumes and positive end expiratory pressures （PEEPs） during mechanical ventilation on the cardiac output of pigs measured by pulmonary artery catheter， transpulmonary thermodilution and pulse contour analysis， and to explore their consistency in cardiac output determination. MethodsTwelve experimental pigs were selected and randomly divided into 3 groups， with 4 pigs in each. Cardiac output was measured by different methods， control group by pulmonary artery catheter， group A by transpulmonary thermodilution and group B by pulse contour analysis. Then we compared the effects of different tidal volumes and PEEPs on the cardiac output of pigs and to explore the consistency. The correlation coefficient between pulse contour analysis and pulmonary artery catheter was r=0.754， and they were positively correlated. The correlation coefficient between transpulmonary thermodilution and pulmonary artery catheter was r=0.771， and they were positively correlated. In determining cardiac output， pulse contour analysis was consistent with pulmonary artery catheter， with a relative error of 13.5% between them； transpulmonary thermodilution was consistent with pulmonary artery catheter， with a relative error of 12.9% between them. The cardiac output decreased significantly along with the increase of tidal volumes or PEEPs and the differences were statistically significant （P<0.05） ConclusionPulmonary artery catheter， transpulmonary thermodilution and pulse contour analysis are well consistent with each other in measuring the cardiac output of pigs. The pigs’cardiac output gradually decreased along with the increase of tidal volumes or PEEPs during mechanical ventilation.

Efeitos da PEEP na ventilação controlada a volume sobre parâmetros hemodinâmicos em suínos submetidos ao pneumoperitônio associado ao cefalodeclive / Effects of PEEP on hemodynamic variables in pigs submitted to volume-controlled ventilation under pneumoperitoneum associated to cephalodeclive

Videolaparoscopic procedures have gained prominence due to their low invasiveness, causing less surgical trauma and better post-surgical recovery. However, the increase in intra-abdominal pressure due to the institution of pneumoperitoneum can alter the patient's homeostasis. Therefore, volume-controlled ventilation, associated with positive end-expiratory pressure (PEEP), improves arterial oxygenation and prevents pulmonary collapse, but it can lead to important hemodynamic changes. The aim of this study was to evaluate, comparatively, the effects of positive end expiratorypressure (PEEP) on hemodynamic variables of pigs submitted to volume-controlled ventilation, during pneumoperitoneum and maintained in head-down tilt and determine which PEEP value promotes greater stability on hemodynamic variables. Twenty-four pigs were used, between 55 and 65-day-old, weighing between 15 and 25 kg, randomly divided into 3 distinct groups differentiated by positive end-expiratory pressure: PEEP 0 (volume-controlled ventilation and PEEP of 0 cmH2O), PEEP 5 (volume-controlled ventilation and PEEP of 5 cmH2O) and PEEP 10 (volume-controlled ventilation and PEEP of 10 cmH2O). Volume-controlled ventilation was adjusted to 8 mL/kg of tidal volume and a respiratory rate of 25 movements per min. Anesthesia was maintained with continuous infusion of propofol (0.2 mg/kg/min) and midazolam (1 mg/kg/h). Pneumoperitoneum was performed with carbon dioxide (CO2), keeping the intraabdominal pressure at 15 mmHg and the animals were positioned on a 30° head-down tilt. The evaluations of hemodynamic variables started 30 min after induction of anesthesia (M0), followed by measurements at 15-min intervals (from M15 to M90), completing a total of 7 evaluations. The variables of interest were collected over 90 min and submitted to analysis of variance followed by Tukey's post-hoc test, with P < 0.05. The PEEP 10 group had higher values of CVP and mCPP, while the PEEP 5 group, mPAP and PVR were higher. The PEEP 0 group, on the other hand, had higher means of CI. Regarding the moments, there were differences in HR, SAP, DAP, MAP, CO, IC and TPR. According to the literature, important hemodynamic effects due to pneumoperitoneum are reported, which can be caused by the pressure used in abdominal insufflation, CO2 accumulation, duration of the surgical procedure, hydration status and patient positioning. Mechanical ventilation associated with PEEP can also cause an increase in intrathoracic pressure and, therefore, reduce cardiac output. Cardiovascular changes are proportional to the PEEP used. Central venous pressure (PVC) measure the patient's preload, and intrathoracic pressure can interfere with this parameter. The peak pressure values in the PEEP 10 group were higher than the other groups, demonstrating that the increase in intrathoracic pressure results in higher PVC values. Regarding PAPm and PCPm, these variables can be influenced according to the PEEP values and the patient's position. In relation to CI, the increase in PEEP may reflect on intrathoracic pressure, resulting in greater compression of the heart, with a consequent reduction in cardiac output and cardiac index. Therefore, it is concluded that the PEEP effects of 0 cmH2O and 5 cmH2O on hemodynamics are discrete, under the proposed conditions.(AU)

Índices de oxigenación en los pacientes neuroquirúrgicos utilizando dos estrategias ventilatorias en el perioperatorio / Index of oxygenation in neurosurgical patients using two ventilatory strategies on the perioperatory / Índices de oxigenação em pacientes neurocirúrgicos utilizando duas estratégias ventilatórias no perioperatório

Resumen: Introducción: La comorbilidad pulmonar postoperatoria dependerá de factores relacionados con el paciente, modificables y no modificables, pero definitivamente los parámetros ventilatorios intraoperatorios tienen un rol fundamental. Existen índices de oxigenación (IO) que pueden resultar útiles en la evaluación del grado de lesión pulmonar. Material y métodos: Estudio prospectivo, descriptivo, analítico, de casos y controles. Pacientes que requirieron intervención neuroquirúrgica (urgente o electiva) y ventilación mecánica invasiva para el procedimiento. Durante el periodo comprendido entre el 1o de enero de 2018 al 31 de diciembre de 2018. Los pacientes que cumplieron con los criterios de inclusión se asignaron uno a uno para pertenecer al grupo Vt Intermedio (> 8 a < 10 mL/kg peso predicho) o al grupo Vt Bajo (6-8 mL/kg peso predicho). La PEEP fue determinada a consideración del médico (anestesiólogo). Resultados: En el periodo considerado se incluyeron 60 pacientes, los cuales cumplieron con los criterios de inclusión. Del total, 30 pacientes se incluyeron en el grupo Vt Intermedio (VtI) y 30 pacientes en el grupo Vt Bajo (VtB). La modalidad ventilatoria más utilizada fue asisto-control-volumen (ACV) con 96.7% para VtI y 100% para VtB con p = 0.3. El Vt por peso predicho en el grupo de VtI tuvo una media de 8.9 mL/kg y en el grupo de VtB una media de 7.1 mL/kg con una p = 0.001. La escala de coma de Glasgow (ECG) posterior a la extubación fue de 14.3 puntos y 14.4 puntos para VtI y VtB sin diferencia estadísticamente significativa. Conclusión: Utilizar volumen corriente intermedio (> 8 a < 10 mL/kg peso predicho) en los pacientes neuroquirúrgicos ocasiona alteración de los índices de oxigenación: PaO2/FiO2 y PaO2/PAO2. El nivel de PEEP durante el perioperatorio de los pacientes neuroquirúrgicos no ocasiona diferencia significativa en la escala de coma de Glasgow.

Abstract: Introduction: Postoperative pulmonary comorbidity will depend on factors related to the patient, modifiable and non-modifiable, but intraoperative ventilatory parameters definitely play a fundamental role. There are oxygenation indices (OI) that may be useful in assessing the degree of lung injury. Material and methods: Prospective, descriptive, analytical, case-control study. Patients who required neurosurgical intervention (urgent or elective) and invasive mechanical ventilation for the procedure. During the period from January 1, 2018 to December 31, 2018. Patients who met the inclusion criteria were assigned 1 to 1 to belong to the Intermediate Tidal Volumen group (ItV) (> 8 to < 10 mL/kg predicted weight) or to the Low Tidal Volumen group (LtV) (6-8 mL/kg predicted weight). PEEP was determined for the doctor's consideration (anesthesiologist). Results: In the period considered, 60 patients were included who met the inclusion criteria. Of the total, 30 patients were included in the ItV group and 30 patients in the LtV group. The most commonly used ventilatory modality was asysto-control-volume (ACV) with 96.7% for ItV and 100% for LtV with p = 0.3. The predicted weight tV in the ItV group had an average of 8.9 mL/kg and in the LtV group an average of 7.1 mL/kg with a p = 0.001 The Glasgow coma scale (GCE) after extubation was of 14.3 points and 14.4 points for ItV and LtV without statistically significant difference. Conclusion: Using intermediate tidal volume (> 8 to < 10 mL/kg predicted weight) in neurosurgical patients, causes alteration of oxygenation rates: PaO2/FiO2 and PaO2/PAO2. The level of PEEP during the perioperative period of neurosurgical patients does not cause a significant difference in the Glasgow coma scale.

Resumo: Introdução: A comorbidade pulmonar pós-operatória vai depender de fatores relacionados ao paciente, modificáveis e não modificáveis, mas os parâmetros ventilatórios intra-operatórios certamente têm papel fundamental. Existem índices de oxigenação (IO) que podem ser úteis na avaliação do grau de lesão pulmonar. Material e métodos: Estudo prospectivo, descritivo, analítico, caso-controle. Pacientes que necessitaram de intervenção neurocirúrgica (urgente ou eletiva) e ventilação mecânica invasiva para o procedimento. Durante o período de 1o de janeiro de 2018 a 31 de dezembro de 2018. Os pacientes que preencheram os critérios de inclusão foram designados de 1 a 1 para pertencer ao grupo Vt Intermediário (> 8 a < 10 mL/kg de peso previsto) ou para o grupo Vt Baixo (6-8 mL/kg de peso previsto). A PEEP foi determinada por consideração do médico (anestesiologista). Resultados: No período considerado, foram incluídos 60 pacientes que atenderam aos critérios de inclusão. Do total, 30 pacientes foram incluídos no grupo Vt Intermediário (VtI) e 30 pacientes no grupo Vt Baixo (VtB). A modalidade ventilatória mais utilizada foi o volume assistido-controlado (VAC) com 96.7% para VtI e 100% para VtB com p = 0.3. O Vt previsto em peso no grupo VtI teve média de 8.9 mL/kg e no grupo VtB média de 7.1 mL/kg com p = 0.001. A escala de coma de Glasgow (ECG) após a extubação foi de 14.3 pontos e 14.4 pontos para VtI e VtB sem diferença estatisticamente significativa. Conclusão: O uso de volume corrente intermediário (> 8 a < 10 mL/kg de peso previsto) em pacientes neurocirúrgicos causa alteração nos índices de oxigenação: PaO2/FiO2 e PaO2/PAO2. O nível de PEEP durante o período perioperatório de pacientes neurocirúrgicos não causa diferença significativa na escala de coma de Glasgow.

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.

Comparison of three lung recruitment maneuvers in the treatment of severe extra-pulmonary acute respiratory distress syndrome / 中国综合临床

Objective To investigate the efficacy and side effects of three recruitment maneuvers (RM) for severe extra-pulmonary acute respiratory distress syndrome ( ARDS). Methods A total of sixty-three extra-pulmonary ARDS patients were enrolled and randomly divided into three groups, which were treated with sustained inflation (SI),increment of positive end-expiratory pressure (IP) and pressure control ventilation (PCV) respectively. The oxygenation index ( PaO2/FiO2) before and after lung recruitment was recorded in patients with complete lung recruitment,and the cause of discontinuation of lung recruitment was recorded in patients with incomplete lung recruitment. Positive end-expiratory pressure (PEEP) was recorded in patients who completed lung recruitment with the latter two methods when they reached the maximum degree of lung recruitment. The mortality rate of 14 d in 3 groups was recorded, and the clinical characteristics and prognosis differences were compared before and after each group. Results With PaO2/FiO2as the standard, all the three methods of pulmonary reexpansion could make the lungs obviously reexpanse. The PaO2/FiO2of each group before, 5 minutes after and 1 hour after reexpansion were respectively as below (SI group: 70. 4±14. 8 mmHg,306. 8±97. 5 mmHg,229. 6±116. 2 mmHg; IP group:74. 9±13. 6 mmHg,328. 0 ± 95. 5 mmHg,252. 8 ± 111. 0 mmHg; PCV group: 67. 8 ± 14. 9 mmHg, 304. 2 ±82. 2 mmHg,223. 7±83. 6 mmHg. P＜0. 01). There were no significant differences among the three methods in the effect of RM (P＞0. 05). PEEP of IP group is higher than that of PCV group at the time of maximum RM (20. 3±2. 5 cmH2O vs. 18. 5±1. 8 cmH2O,P＜0. 05). There were significant differences in the incidence of adverse reactions caused by the three methods (54. 5%(12/22) in SI group,35. 0%(7/20) in IP group and 9. 6%(2/21) in PCV group. The 14 d mortality of each group was 63. 6%(14/22) in SI group,70. 0%(14/20) in IP group and 61. 9%(13/21) in PCV group,with no significant difference (P＞0. 05) . Conclusion The effects of three methods of lung recruitment on severe pulmonary exogenous ARDS patients were similar, but there was no significant difference in prognosis. Adverse reactions of SI method leads to the greatest probability of discontinuation of lung recruitment,and that of the PCV method is the smallest. Under the same effect of lung recruitment, IP method needs higher PEEP than PCV method. In practice,PCV method should be preferred.

The predictive value of cardiopulmonary interaction monitoring technology on volume responsiveness in septic shock patients / 中华急诊医学杂志

Objective To assess the predictive value of cardiopulmonary interaction monitoring technology on volume responsiveness in septic shock patients.Methods A cohort of 45 septic shock patients treated with mechanical ventilation at First People's Hospital of Nantong City from January 2016 to June 2017 were prospectively selected.The hemodynamic variables including heart rate (HR),systolic pressure (SBP),mean arterial pressure (MAP),central venous pressure (CVP),cardiac index (CI),stroke volume variability (SVV),and pulse pressure variability (PPV) were monitored.PEEP elevation test,end-expiratory occlusion test and volume expansion were sequential conducted.Volume responsiveness was defined as an increase in CI (△CI) of 15％ or greater after volume expansion,namely the response group (△CI ≥ 15％) and non-response group (△CI＜15％).Receiver operating characteristic (ROC) curve was constructed to indicate the predictive value of cardiopulmonary interaction monitoring technology in septic shock patients.The best cut-off value was assessed by Youden Index,and sensitivity and specificity were calculated respectively.Results There were 24 patients in the response group and 21 patients in the non-response group.There were no significant differences in basic clinical data between the two groups.△fter PEEP elevation test,CVP increased significantly,while SBP and CI decreased significantly in both groups (P＜0.05).The degrees of △SBP and △CI in the response group were much higher than those in the non-response group (P＜0.05).After end-expiratory occlusion test,CVP decreased significantly,while SBP,MAP and CI increased significantly in both groups (P＜0.05).The degrees of △MAP and △CI in the response group were much higher than those in the non-response group (P＜0.05).SVV and PPV in the response group were higher than those in the non-response group (P＜0.05).The area under the ROC curve (AUC) of the △SBP and △CI after PEEP elevation test and △MAP and △CI after end-expiratory occlusion test were 0.737 (95％CI:0.581-0.89;P＜0.05),0.803 (95％CI:0.660-0.946;P＜0.05),0.763 (95％CI:0.617-0.908;P＜0.05),and 0.808 (95％CI:0.673-0.942;P＜0.05),respectively.These AUC values were higher than or similar to traditional indicators,such as SVV and PPV.The best cut-off value of △CI and △SBP after PEEP elevation test was 12％ and 9.5％,yielding a sensitivity and specificity of 70.8％and 95.2％,75％ and 71.4％,respectively.The best cut-off value of △CI and △MAP after end-expiratory occlusion test was 8.5％ and 5.5％,yielding a sensitivity and specificity of 79.2％ and 76.2％,75％ and 76.2％ respectively.Conclusion △SBP and △CI after PEEP elevation test and △MAP and △CI after endexpiratory occlusion test can accurately predict volume responsiveness in septic shock patients.

Application of low tidal volume, apnea ventilation and low PEEP in soft ureteroscope surgery / 中国内镜杂志

Objective To research the application of low tidal volume, apnea ventilation and low PEEP in soft ureteroscope surgery. Methods 80 patients with renal calculi who underwent ureteroscopic holmium laser lithotripsy were randomly divided into tow groups, 40 patients in each group. The observation group was treated with low tidal volume, apnea ventilation and Low PEEP, and the control group was treated with low tidal volume and apnea ventilation. Recorded the HR, MBP, PaCO2, PaO2, Ppeak, A-aDO2, and recorded A-aDO2at pre-anesthesia, preoperation, tracheal extubation, 30 min after tracheal extubation and 24 hours after surgery in tow groups. And observed the trend of RI and CLdyn in tow groups. Results There were no satistically significant differences of HR, MBP, Ppeak and Pmean after recovery and that before apnea in the observation group (P > 0.05); the HR, MBP, Ppeak and Pmean of the observation group was lower than that of the control group after recovery (P < 0.05); the PaO2 of the observation group was higher than that of the control group after recovery (P < 0.05); at tracheal extubation, 30min after tracheal extubation and 24 hours after surgery, the A-aDO2 of the observation group was lower than thatof the control group (P < 0.05); the CLdyn 20 in the observation group was better than that in the control group(P < 0.05). Conclusion In soft ureteroscope surgery, the application of Low tidal volume, apnea ventilation andlow PEEP can ensure the asfe of operation, and maintain the vital aspect, results of blood gas analysis smoothly; andprotect the lung function, promote the recovery of the patients.

Application of electrical impedance tomography for postoperative lung recruitment in patients undergoing off pump coronary artery bypass grafting surgery / 上海交通大学学报（医学版）

Objective • To find out the optimal positive end expiratory pressure (PEEP) by electrical impedance tomography (EIT) for better lung recruitment and ventilation distribution in patients undergoing off pump coronary artery bypass grafting surgery (OPCAB). Methods • 105 patients underwent OPCAB from Jan. 2017 to Dec. 2017 were analysed. Patients were randomly divided into two groups, i.e. experiment group (54 cases) and control group (51 cases). Four regions of interest (ROI) were recorded by EIT. PEEP were 3 cmH2O in control group while PEEP were increased stepwise by 2 cmH2O from 0 cmH2O to 14 cmH2O in experiment group. The optimal PEEP for lung recruitment was applied in experiment group. Postoperative oxygenation index (PaO2/FiO2) and pulmonary complication were compared between two groups. Results • The overall mortality was 2 (1.90%). The incidence of postoperative pulmonary complication, pulmonary infection, atelectasis, pleural effusion were 18.10%, 2.86%, 18.10%, 18.10%, respectively. The optimal PEEP zone was 6-9 cmH2O. PaO2/FiO2 was significantly increased with the optimal PEEP in experiment group (P=0.00). There were significant differences in postoperative pulmonary complication between two groups (P=0.02). Conclusion • EIT can directly monitor ventilation distribution and titrate suitable PEEP for better lung recruitment in patients undergoing OPCAB. It can significantly reduce postoperative pulmonary complication, improve oxygenation, and decrease ICU stay and ventilation duration.

Application of electrical impedance tomography for postoperative lung recruitment in patients undergoing off pump coronary artery bypass grafting surgery / 上海交通大学学报（医学版）

Objective·To find out the optimal positive end expiratory pressure (PEEP) by electrical impedance tomography (EIT) for better lung recruitment and ventilation distribution in patients undergoing off pump coronary artery bypass grafting surgery (OPCAB). Methods?·?105 patients underwent OPCAB from Jan. 2017 to Dec. 2017 were analysed. Patients were randomly divided into two groups, i.e. experiment group (54 cases) and control group (51 cases). Four regions of interest (ROI) were recorded by EIT. PEEP were 3?cmH2O in control group while PEEP were increased stepwise by 2?cmH2O from 0?cmH2O to 14?cmH2O in experiment group. The optimal PEEP for lung recruitment was applied in experiment group. Postoperative oxygenation index (PaO2/FiO2) and pulmonary complication were compared between two groups. Results?·?The overall mortality was 2 (1.90%). The incidence of postoperative pulmonary complication, pulmonary infection, atelectasis, pleural effusion were 18.10%, 2.86%, 18.10%, 18.10%, respectively. The optimal PEEP zone was 6-9?cmH2O. PaO2/FiO2was significantly increased with the optimal PEEP in experiment group (P=0.00). There were significant differences in postoperative pulmonary complication between two groups (P=0.02). Conclusion?·?EIT can directly monitor ventilation distribution and titrate suitable PEEP for better lung recruitment in patients undergoing OPCAB. It can significantly reduce postoperative pulmonary complication, improve oxygenation, and decrease ICU stay and ventilation duration.

Utilidad del ultrasonido de pulmón en la titulación de la PEEP en pacientes con síndrome de insuficiencia respiratoria aguda clasificación Berlín moderado y grave / Utility of lung ultrasound for PEEP titration in patients with acute respiratory distress syndrome with Berlin classification moderate and severe / Utilidade do ultrassom pulmonar na titulação da PEEP em pacientes con síndrome de dificuldade respiratória aguda classificação Berlim moderada e grave

Resumen: La ventilación mecánica es una de las herramientas que tenemos en el manejo del síndrome de insuficiencia respiratoria aguda (SDRA); la PEEP es una de las variables que nos permiten mejorar a estos pacientes. El ultrasonido de pulmón es cada vez más empleado en terapia intensiva, por lo que incorporarlo de forma rutinaria a la titulación de la PEEP (presión positiva al final de la espiración) puede ser un acierto. Realizamos de manera prospectiva la titulación de la PEEP en 20 individuos con SDRA y se efectuaron mediciones al pie de cama por medio de ultrasonido de pulmón. Objetivos: Objetivo primario: Evaluar la utilidad del ultrasonido pulmonar (USP) para la titulación de la PEEP. Objetivo secundario: Analizar diferentes métodos de titulación de la PEEP y analizar la respuesta a la PEEP con base en el potencial de reclutamiento calculado por USP. Material y métodos: Estudio prospectivo y observacional. Criterios de inclusión: Sujetos mayores de 18 años con SDRA moderado y severo de acuerdo a la clasificación de Berlín. Resultados: Veinte personas (p), 11 hombres (55%), nueve mujeres (45%); 16 (80%) con PaO2/FiO2 ≤ 150 mmHg y cuatro (20%) con PaO2/FiO2 > 150 mmHg. BNP en 19 p (95%); de estos, 11 (57%) ≤ 250 ng/dL y nueve (42.2%) > 250 ng/dL. En 17 p (85%) se evidenció potencial de reclutamiento, representado por incremento de distensibilidad de 1 mL/cmH2O y disminución de 1% del espacio muerto. En la titulación por curva de flujos lentos, el punto de inflexión inferior fue en promedio 7.2 cmH2O, el superior, 21.9 cmH2O, el medio, 13.5 cmH2O; el volumen inferior, 105.1 mL, el volumen superior, 428.7 mL. Se tituló la PEEP por mejor distensibilidad en 19 p (95%), programándose 16 cmH2O en 5 p (26%), 14 cmH2O (15.7%), 12 cmH2O (21%), 10 cmH2O (15.7%) y 8 cmH2O (26.3%). Se logró realizar USP en 14 p (70%). Conclusiones: Realizar USP a la cabecera del enfermo es factible y útil en la titulación de la PEEP sin riesgos. Es otra herramienta en la identificación de sobredistensión pulmonar.

Abstract: Mechanical ventilation is a cornerstone in the management of acute respiratory distress syndrome (ARDS). PEEP is a strategy that improves the patient's outcome. Lung ultrasound is now a main tool in the intensive care unit; therefore, it could have a role in the titration of PEEP. We conducted a prospective study in 20 patients with ARDS, and titrated PEEP with lung ultrasound at the bedside. Objectives: Primary objective: Assessing the usefulness of lung ultrasound for PEEP titration in ARDS. Secondary objective: To compare four methods of PEEP titration with lung ultrasound findings. Material and methods: Prospective and observation study. Inclusion criteria: Patients with moderate and severe ARDS according to the Berlin classification, 18 years and older. Results: Twenty patients (p), 11 males (55%), nine females (45%); 16 (80%) with PaO2/FiO2 ≤ 150 mmHg and four (20%) with PaO2/FiO2 > 150 mmHg. BNP in 19 p (95%); 11 of them (57%) ≤ 250 ng/dL and nine (42.2%) > 250 ng/dL. In 17 p (85%), a recruitment potential was observed, represented by an increase of compliance by 1 mL/cmH2O or decrease of 1% in death space. Using slow-flow curve, the mean lower inflection point was 7.2 cmH2O, the upper inflection point was 21.9 cmH2O, and the middle was 13.5 cmH2O; the lower volume, 105.1 mL, the higher volume, 428.7 mL. The best compliance method was also performed on 19 of these patients (95%); then, PEEP was titrated in 16 cmH2O in 5p (26%), 14 cmH2O (15.7%), 12 cmH2O (21%), 10 cmH2O (15.7%) and 8 cmH2O (26.3%). Lung ultrasound could be performed in 14 patients (70%). Conclusions: It is feasible to perform a lung ultrasound at the patient's bedside. It may be useful in the titration of PEEP, without risks for the patient. It may be another tool for the prevention of lung overdistension.

Resumo: A ventilação mecânica é uma das ferramentas que temos no tratamento da dificuldade respiratória aguda (SDRA), a PEEP é uma das variáveis que nos permitem melhorar estes pacientes. O ultrassom pulmonar é cada vez mais utilizado na terapia intensiva, a incorporação rotinária da titulação da PEEP pode ser uma boa opção. Realizamos de maneira prospectiva a titulação da PEEP em 20 pacientes com SDRA e se efetuaram medições à beira do leito mediante ultrassom pulmonar. Objetivos: Objetivo primário: avaliar a utilidade do ultrassom pulmonar (USP) para a titulação da PEEP. Objetivo secundário: comparar 4 métodos de titulação da PEEP com achados ultrassonográficos no pulmão (USP). Material e métodos: Estudo prospectivo e observacional. Critérios de inclusão: pacientes com SDRA moderada e grave de acordo com a classificação de Berlin, maiores de 18 anos. Resultados: 20 pacientes (p), 11 homens (55%), 9 mulheres (45%), 16 (80%) com PaO2/FiO2 ≤150 mmHg e 4 (20%) PaO2/FiO2 > 150 mmHg, BNP em 19 p (95%) destes 11 (57%) ≤ 250 ng/dL e 9 (42.2%) > 250 ng/dL, em 17 p (85%) se evidenciou potencial de recrutamento, representado pelo aumento na distensibilidade 1 mL/cm H2O e diminuição de 1% do espaço morto. Na titulação pela curva de fluxos lentos o ponto de inflexão inferior, foi em média, 7.2 cmH2O, o superior 21.9 cmH2O, o médio 13.5 cmH2O, o volume inferior 105.1 mL, o volume superior 428.7 mL. PEEP foi titulada por uma melhor distensibilidade em 19 p (95%), programando 16 cmH2O em 5 p (26%), 14 cmH2O (15.7%), 12 cmH2O (21%), 10 cmH2O (15.7%) e 8 cmH2O (26.3%). Realizamos USP em 14 p (70%). Conclusões: Realizar USP à beira do leito é viável e é útil na titulação da PEEP sem riscos. É uma outra ferramenta para a identificação de hiperdistensão pulmonar.

Effects of different levels of end-expiratory pressure on hemodynamic, respiratory mechanics and systemic stress response during laparoscopic cholecystectomy / Efeitos de diferentes níveis de pressão expiratória final sobre a hemodinâmica, mecânica respiratória e resposta sistêmica ao estresse durante colecistectomia laparoscópica

Abstract Objective: General anesthesia causes reduction of functional residual capacity. And this decrease can lead to atelectasis and intrapulmonary shunting in the lung. In this study we want to evaluate the effects of 5 and 10 cmH2O PEEP levels on gas exchange, hemodynamic, respiratory mechanics and systemic stress response in laparoscopic cholecystectomy. Methods: American Society of Anesthesiologist I-II physical status 43 patients scheduled for laparoscopic cholecystectomy were randomly selected to receive external PEEP of 5 cmH2O (PEEP 5 group) or 10 cmH2O PEEP (PEEP 10 group) during pneumoperitoneum. Basal hemodynamic parameters were recorded, and arterial blood gases (ABG) and blood sampling were done for cortisol, insulin and glucose level estimations to assess the systemic stress response before induction of anesthesia. Thirty minutes after the pneumoperitoneum, the respiratory and hemodynamic parameters were recorded again and ABG and sampling for cortisol, insulin, and glucose levels were repeated. Lastly hemodynamic parameters were recorded; ABG analysis and sampling for stress response levels were taken after 60 minutes from extubation. Results: There were no statistical differences between the two groups about hemodynamic and respiratory parameters except mean airway pressure (P mean). P mean, compliance and PaO2; pH values were higher in 'PEEP 10 group'. Also, PaCO2 values were lower in 'PEEP 10 group'. No differences were observed between insulin and lactic acid levels in the two groups. But postoperative cortisol level was significantly lower in 'PEEP 10 group'. Conclusion: Ventilation with 10 cmH2O PEEP increases compliance and oxygenation, does not cause hemodynamic and respiratory complications and reduces the postoperative stress response.

Resumo Objetivo: A anestesia geral causa a redução da capacidade residual funcional e essa diminuição pode levar à atelectasia pulmonar e ao shunt intrapulmonar. Neste estudo pretendemos avaliar os efeitos de níveis de 5 e 10 cmH2O de pressão expiratória final positiva (PEEP) sobre as trocas gasosas, a hemodinâmica, a mecânica respiratória e a resposta ao estresse sistêmico em colecistectomia laparoscópica. Método: Foram selecionados aleatoriamente 43 pacientes, estado físico ASA I-II, agendados para colecistectomia laparoscópica, para receber PEEP a 5 cmH2O (grupo PEEP-5) ou PEEP de 10 cmH2O (grupo PEEP-10) durante o pneumoperitônio. Os parâmetros hemodinâmicos foram registrados, gasometria arterial e coleta de sangue foram feitas para estimativa dos níveis de cortisol, insulina e glicose para avaliar a resposta ao estresse sistêmico antes da indução anestésica. Trinta minutos após o pneumoperitônio, os parâmetros hemodinâmicos e respiratórios foram registrados novamente e gasometria e amostragem para os níveis de cortisol, insulina e glicose foram repetidos. E os últimos parâmetros hemodinâmicos foram registrados, análise e amostragem de gasometria para os níveis de resposta ao estresse foram feitas após 60 minutos da extubação. Resultados: Não houve diferença estatística entre dois grupos quanto aos parâmetros hemodinâmicos e respiratórios, exceto pressão média das vias aéreas (Pmédia). Os valores de Pmédia, complacência, PaO2 e do pH foram maiores no grupo PEEP-10. Também os valores de PaCO2 foram menores no grupo PEEP-10. Não foram observadas quaisquer diferenças entre os níveis de insulina e de ácido láctico nos dois grupos. Porém, o nível de cortisol no pós-operatório foi significativamente menor no grupo PEEP-10. Conclusão: Ventilação com PEEP de 10 cmH2O aumenta a complacência e a oxigenação, não causa hemodinâmica e complicações respiratórias e reduz a resposta ao estresse no pós-operatório.

The effects of different values of PEEP on heart index, stroke volume variation and oxygen transport index in patients monitored by FloTrac/Vigileo system / 天津医药

Objective To investigate the effects of different values of PEEP on cardiac index (CI), stroke volume variation (SVV) and oxygen transport index (DO2I) in patients monitored by FloTrac/Vigileo system, and to provide some references for the hemodynamic management and improvement of oxygenation for patients. Methods Sixty patients scheduled for elective television (TV) auxiliary thoracoscope radical operation for esophageal cancer were included in this study. Data of CI, SVV and DO2I were observed by the FloTrac/Vigileo system. Changes of CI, SVV and DO2I were recorded after anesthesia induction and turn left side (T0), artificial pneumothorax with 0 PEEP after 5 minutes (T1), artificial pneumothorax with 5 PEEP after 5 minutes (T2), artificial pneumothorax with 10 PEEP after 5 minutes (T3), and artificial pneumothorax with 15 PEEP after 5 minutes (T4). Results Compared with T0, CI decreased and SVV increased significantly at T1, T2, T3 and T4(P<0.05). Compared with T1, CI decreased and SVV increased at T4. DO2I increased at T2 and T3 compared with that of T1(P<0.05). Conclusion PEEP may have a certain influence on CI and SVV in the process of operation. The values of 5-10 PEEP can significantly improve oxygenation and have a less influence on hemodynamics, which can be appropriately used in clinical care.

Síndrome de distrés respiratorio agudo / Acute respiratory distress syndrome

El síndrome de distrés respiratorio agudo (SDRA) es una insuficiencia respiratoria aguda secundaria a edema pulmonar inflamatorio, con aumento de permeabilidad capilar, inundación alveolar e hipoxemia profunda subsiguiente. El trastorno subyacente es la presencia de shunt intrapulmonar, característicamente refractario a las FIO2 elevadas. El SDRA se manifiesta dentro de la semana de la exposición a un factor de riesgo, habitualmente neumonía, shock, sepsis, aspiración de contenido gástrico, trauma, y otros. En la tomografía axial computarizada (TAC) la enfermedad frecuentemente aparece como no homogénea, con infiltrados gravitacionales coexistiendo con áreas normalmente aireadas y otras hiperinsufladas. La mortalidad es elevada (30-60%), especialmente en el SDRA secundario a shock séptico e injuria cerebral aguda. El tratamiento es el del factor de riesgo, junto con la ventilación mecánica que, inapropiadamente utilizada, puede también inducir injuria. El uso de un volumen corriente ≤ 6 ml/kg de peso corporal ideal como para mantener una presión de fin de inspiración (plateau) ≤ 30 cm H2O ("ventilación protectora") se asocia a una disminución de la mortalidad. Niveles de presión positiva de fin de espiración (PEEP) moderados-altos son frecuentemente necesarios para tratar la hipoxemia, pero no existe un único valor predeterminado o un método específico de titular PEEP para disminuir la mortalidad. Recientemente, la utilización precoz del decúbito prono en pacientes con PaO2/FIO2 ≤150 se asoció a un aumento de supervivencia. En la hipoxemia grave, pueden utilizarse adyuvantes de la ventilación mecánica como maniobras de reclutamiento, bloqueantes neuromusculares y oxigenación por membrana extracorpórea. La restricción en los fluidos resulta beneficiosa.

Acute respiratory distress syndrome (ARDS) is an acute respiratory failure produced by an inflammatory edema secondary to increased lung capillary permeability. This causes alveolar flooding and subsequently deep hypoxemia, with intrapulmonary shunt as its most important underlying mechanism. Characteristically, this alteration is unresponsive to high FIO2 and only reverses with end-expiratory positive pressure (PEEP). Pulmonary infiltrates on CXR and CT are the hallmark, together with decreased lung compliance. ARDS always occurs within a week of exposition to a precipitating factor; most frequently pneumonia, shock, aspiration of gastric contents, sepsis, and trauma. In CT scan, the disease is frequently inhomogeneous, with gravitational infiltrates coexisting with normal-density areas and also with hyperaerated parenchyma. Mortality is high (30-60%) especially in ARDS associated with septic shock and neurocritical diseases. The cornerstone of therapy lies in the treatment of the underlying cause and in the use mechanical ventilation which, if inappropriately administered, can lead to ventilator-induced lung injury. Tidal volume ≤ 6 ml/kg of ideal body weight to maintain an end-inspiratory (plateau) pressure ≤ 30 cm H2O ("protective ventilation") is the only variable consistently associated with decreased mortality. Moderate-to-high PEEP levels are frequently required to treat hypoxemia, yet no specific level or titration strategy has improved outcomes. Recently, the use of early prone positioning in patients with PaO2/FIO2 ≤ 150 was associated with increased survival. In severely hypoxemic patients, it may be necessary to use adjuvants of mechanical ventilation as recruitment maneuvers, pressure-controlled modes, neuromuscular blocking agents, and extracorporeal-membrane oxygenation. Fluid restriction appears beneficial.

Efecto del incremento de la PEEP en la actividad muscular respiratoria evaluado con electromiografía de superficie en individuos sanos bajo ventilación espontánea / Effect of PEEP increase on respiratory muscle activity assessed through surface electromyography in healthy subjects during spontaneous breathing / Efeito do incremento da PEEP na atividade mus-cular respiratória avaliado com eletromiografia de superfície em indivíduos saudáveis sob ventilação espontânea

Introducción: en un paciente bajo ventilación mecánica con resistencia aumentada de la vía aérea, la duración de la fase espiratoria es insuficiente para exhalar todo el volumen inspirado. Para mantener la oxigenación y reducir el trabajo de los músculos respiratorios, es común aplicar una presión positiva al final de la espiración (PEEP), que reduce la colapsabilidad del tejido, compensando el aumento de la resistencia. Diversos estudios han demostrado la utilidad de la electromiografía de superficie (EMGS) para cuantificar el trabajo respiratorio. Objetivo: evaluar el efecto de la PEEP en la actividad muscular respiratoria mediante EMGS en individuos sanos bajo ventilación mecánica no invasiva. Metodología: estudio de la actividad muscular en 10 hombres voluntarios sanos ventilados de manera no invasiva con variaciones de la PEEP desde 0 hasta 5 cm H2O en pasos de 1 cm H2O, cada 30 segundos. Resultados: los biopotenciales del diafragma y el esternocleidomastoideo permitieron detectar diferentes respuestas ante el estímulo incremental: 1) aumento del trabajo de los dos músculos durante la inspiración y la espiración; 2) aumento de la actividad en solo uno de los músculos; 3) aumento del trabajo muscular exclusivamente durante la espiración. Conclusión: en individuos ventilados de forma no invasiva, la EMGS relaciona cuantitativamente el nivel de PEEP con el cambio en la actividad del diafragma y el esternocleidomastoideo.

Introduction: In a mechanically ventilated patient with increased airway resistance, the expiratory time span is insufficient to exhale all the inspired volume. In order to maintain oxygenation and to reduce the workload of respiratory muscles, it is common to apply an extrinsic positive end-expiratory pressure (PEEP) that reduces tissue collapsibility, counterbalancing the increased resistance. Several studies have shown the usefulness of surface electromyography (sEMG) to quantify the work of breathing (WOB), particularly in patients with obstructive diseases. Objective: To assess the effect of incremental PEEP in the respiratory muscle activity through sEMG in healthy volunteers noninvasively ventilated. Methods: Study of muscle activity in 10 healthy male volunteers, noninvasively ventilated for 20 minutes. The extrinsic PEEP was applied from 0 to 5 cm H2O in steps of 1 cm H2O at 30 seconds intervals. Results: The bio-potentials of diaphragm and sternocleidomastoid muscles revealed different breathing patterns in response to incremental PEEP: 1) increase in the workload of both muscles during inspiration and expiration; 2) increase in the workload of only one muscle; 3) a remarkable increase in muscle activity only in expiration. Conclusion: In noninvasively ventilated volunteers, sEMG quantitatively relates the PEEP level with changes in sternocleidomastoid and diaphragm activity.

Introdução: Num paciente sob ventilação mecânica com resistência aumentada da via aérea, a duração da fase respiratória é insuficiente para exalar todo o volume inspirado. Para manter a oxigenação e reduzir o trabalho dos músculos respiratórios, é comum aplicar uma pressão positiva no final da respiração (PEEP), que reduz a colapsabilidade do tecido, compensando o aumento da resistência. Diversos estudos demostraram a utilidade da eletromiografia de superfície (EMGS) para quantificar o trabalho respiratório. Objetivo: avaliar o efeito da PEEP na atividade muscular respiratória mediante EMGS em indivíduos saudáveis sob ventilação mecânica não invasiva. Metodologia: estudo da atividade muscular em 10 homens voluntários saudáveis ventilados de maneira não invasiva com variações da PEEP desde 0 até 5 cm H2O em passos de 1 cm H2O, cada 30 segundos. Resultados: os biopotenciais do diafragma e o esternocleidomastoideo permitiram detectar diferentes respostas ante o estímulo incremental: 1) aumento do trabalho dos dois músculos durante a inspiração e a espiração; 2) aumento da atividade em só um dos músculos; 3) aumento do trabalho muscular exclusivamente durante a espiração. Conclusão: em indivíduos ventilados de forma não invasiva, a EMGS relaciona quantitativamente o nível de PEEP com o câmbio na atividade do diafragma e oesternocleidomastoideo.

The Lazarus Syndrome / 中华急诊医学杂志

The Lazarus phenomenon is defined as delayed ROSC,or ROSC after failure of CPR and cessation of all the emergency medical care,including the cessation of chest compression,mechanical ventilation,and venous fluid resuscitation.It was first reported in 1982 and 53 cases of Lazarus phenomenon have been reported in the medical literature so far.Even though Lazarus phenomenon is rare and the pathophysiological mechanisms are poorly understood,several possible mechanisms are still proposed,which could be rational to explain this phenomenon,such as auto-PEEP,hyperkalemia,alkalosis,delayed action of drugs,etc.In most cases,it was reported that ROSC occurred within 10 minutes after cessation of medical effort.Therefore,before the announcement of death of patient,it is mandatory to monitor those patients for at least 10 minutes after the cessation of CPR.However,more explicit studies seem to be necessary to gain a better understanding of this phenomenon.

Percutaneous tracheostomy by Griggs technique: a retrospective analysis.

Background: The scope of percutaneous tracheostomy (PCT) is increasing with experience with successful conduct in conditions traditionally described as contra indications such as difficult anatomy, bleeding diathesis and high ventilatory requirement. The objectives of this study were to assess the safety of PCT in patients with obesity, short neck, thrombocytopenia, coagulopathy, high FiO2 and PEEP requirement. We also aimed to determine complication rate and average time required. Methods: This retrospective study was conducted in the surgical intensive care unit at a tertiary care centre. Seventy five patients who underwent PCT by Griggs technique, with ultrasonographic and bronchoscopic guidance during a period of one year from January to December 2014 were included. Age, sex, height, weight, BMI, platelet count, INR, crico sternal distance and duration of procedure were noted. We analyzed all high risk factors and peri procedural complications. Results: Obesity was present in 5 (6.66%), short neck in 6 (8%), coagulopathy in 25 (33.33%), thrombocytopenia in 22 (29.33%), high FiO2 requirement in 28 (37.33%) and high PEEP requirement in 30 (40%) patients. Minor complications were present in 11 patients (14.66%). No life threatening complications were noted. One patient required conversion into open tracheostomy. The average time taken for PCT was 4.87 ± 1.1 min. Conclusion: PCT can be safely performed in patients with obesity, short neck, thrombocytopenia, coagulopathy and high ventilatory requirement with minimal complication rate, aided by tools like ultrasonography and fiberoptic bronchoscope.

Auto-PEEP-like condition recognized by a sudden decrease in airway pressure during pressure controlled ventilation and low-flow anesthesia: A case report

During mechanical ventilation in the intensive care unit, auto-positive end-expiratory pressure (auto-PEEP) has been reported to occur in obstructive airway conditions aggravated by inappropriate ventilator settings. In this paper, we report a case of auto-PEEP-like problem during anesthesia, mainly caused by excessive sputum. After being positioned prone for spine surgery, the patient received pressure controlled ventilation at a low fresh gas flow rate. One hour after the start of surgery, sudden decreases in pressure and flow occurred. The typical maneuvers which could be performed by the anesthesiologists in the situations suggesting leakage within the breathing circuit consist of pressing the oxygen flush valve and manual hyperventilation for the initial evaluation. But from our experience in this case, we have learned that such maneuvers could cause unacceptable aggravation in the event of auto-PEEP. Also in this report, we discuss the difficulties in prediction based on the present knowledge of preoperative evaluation and the presumably best management policy regarding this type of auto-PEEP.

Continuous positive airway pressure setups evaluated at simulated exercise conditions

INTRODUCTION: Studies have shown increases in airway opening pressure (Pao) swings and work of breathing (WOB) by different continuous positive airway pressure (CPAP) devices at rest, but few address this issue during exercise. The aim of the present work was to analyze the imposed WOB (WOBi), the apparent resistance (Rapp) and swings of Pao (deltaP) of 3 CPAP assemblies at simulated exercise conditions. METHODS: The CPAP measures were obtained from: a commercial CPAP (Assembly 1), a high flow CPAP (Assembly 2) and the parallel association of these devices (Assembly 3). In each assembly the spring-loaded positive end-expiratory pressure (PEEP) valve was set to fully opened (mode A) or at the same CPAP pressure (mode B). The exercise protocol simulation, performed manually by a calibrated syringe and a metronome, employed a respiratory frequency of 30 bpm, tidal volume of 2.7 L and inspiratory-to-expiratory ratio of 1. The setups were evaluated at CPAP settings of 5, 10 and 15 cmH2O. RESULTS: The lowest deltaP as well as Rapp and WOBi were obtained with Assembly 3 in mode A with an adjusted CPAP of 10 cmH2O (deltaP=8.1 (0.5) cmH2O, WOBi=1.4 (0.14) cmH2O/L/s, Rapp= 1.3 (0.07) J/s) showed as median (interquartile range). CONCLUSION: For the conditions studied, the best CPAP setup was obtained with mode A.

Effects of a preemptive alveolar recruitment strategy on arterial oxygenation during one-lung ventilation with different tidal volumes in patients with normal pulmonary function test / 대한마취과학회지

BACKGROUND: Hypoxemia during one-lung ventilation (OLV) remains a major concern. The present study compared the effect of alveolar recruitment strategy (ARS) on arterial oxygenation during OLV at varying tidal volumes (Vt) with or without positive end-expiratory pressure (PEEP). METHODS: In total, 120 patients undergoing wedge resection by video assisted thoracostomy were randomized into four groups comprising 30 patients each: those administered a 10 ml/kg tidal volume with or without preemptive ARS (Group H and Group H-ARS, respectively) and those administered a 6 ml/kg tidal volume and a 8 cmH2O PEEP with or without preemptive ARS (Group L and Group L-ARS, respectively). ARS was performed using pressure-controlled ventilation with a 40 cmH2O plateau airway pressure and a 15 cmH2O PEEP for at least 10 breaths until OLV began. RESULTS: Preemptive ARS significantly improved the PaO2/FiO2 ratio compared to the groups that did not receive ARS (P < 0.05). The H-ARS group showed a highest PaO2/FiO2 ratio during OLV, the L-ARS and H groups showed similarly improved arterial oxygenation, which was significantly higher than in group L (P < 0.05). The plateau airway pressure in group H-ARS was significantly higher than in group L-ARS (P < 0.05). CONCLUSIONS: Preemptive ARS can improve arterial oxygenation during OLV. Furthermore, a 6 ml/kg tidal volume combined with 8 cmH2O PEEP after preemptive ARS may reduce the risk of pulmonary injury caused by high tidal volume during one-lung ventilation in patients with normal pulmonary function.

Effects of Different PEEP on Abdominal Pressure and Liver in COPD Patients / 天津医药

Objective To research the impact of various PEEP parameters of mechanical ventilation on liver mor-phology and function and on hemodynamics. Methods Fifty patients of respiratory failure due to COPD using mechanical ventilation was observed by prospective, exoterical and self-control methods after their condition were stabilized. The varia-tion of abdominal pressure was measured with different PEEP of 0 cmH2O, 5 cmH2O and 10 cmH2O with mechanical ventila-tion, and measured when patients breathe autonomously with tracheostomy tube. The changes of liver morphology, hepatic por-tal vein diameter, hemodynamics and liver function were also measured on above circumstances. Results With PEEP value increases:the abdominal pressure (IAP) rise (P＜0.01) while liver morphology, function and hepatic portal did not change markedly evidently (P>0.05). By contrast, blood flow of hepatic portal vein reduced with PEEP increase (P＜0.05). Conclu-sion Higher PEEP values on mechanical ventilation will causes abdominal pressure increases and low blood flow of hepatic portal , but not obvious impact on portal vein diameter and liver function.