Dexmedetomidine improves function of lung oxygenation in patients with moderate chronic obstructive pulmonary disease underwent lung cancer surgery / 中南大学学报(医学版)

Objective:To determine whether dexmedetomidine (Dex) improves oxygenation and lung mechanics in patients with moderate chronic obstructive pulmonary disease (COPD) during lung cancer surgery.Methods:Fifty-six patients with moderate COPD were randomly allocated to a control group and a Dex group (n=28 each).In the Dex group,dexmedetomidine was given as an initial loading dose at 1.0 μg/kg lasting for 10 min followed by a maintenance dose at 0.5 μg/(kg-h) during OLV while the control group was administered an equal volume of 0.9％ saline accordingly.Results:Patients in the Dex group had a significantly higher oxygenation index (P＜0.05) and higher dynamic lung compliance at Dex-30 and Dex-60 (P＜0.05) compared with those in the control group.In the Dex group,oxygenation index in the postoperative period was significantly higher (P=0.025) and postoperative complications were lower than those in the control group.Conclusion:Dex administration may provide dinically relevant benefits by improving oxygenation index and lung mechanics,and reducing postoperative pulmonary complications in patients with moderate COPD underwent lung cancer surgery.

Development of different degrees of elastase-induced emphysema in mice: a randomized controlled experimental study

Introduction: Mouse models of emphysema are important tools for testing different therapeutic strategies. The aim of this study was to develop a mouse model of emphysema induced by different doses of elastase in order to produce different degrees of severity. Methods: Thirty female mice (C57BL/6) were used in this study. Different doses of porcine pancreatic elastase were administered intratracheally once a week for four weeks, as follows: 0.1 U (n=8), 0.15 U (n=7), and 0.2 U (n=7). Control mice (n=8) received 50 microL of sterile saline solution intratracheally. Lung mechanics were analyzed by plethysmography. Mean linear intercept and volume fraction occupied by collagen and elastic fibers were determined. Results: An increase in lung resistance was observed with 0.2 U of elastase [median (P-25-P75): 2.02 (1.67; 2.34) cmH2O.s/mL], as well as a decrease in tidal volume and minute ventilation. Peak expiratory flow increased significantly in the groups treated with 0.15 U and 0.2 U of elastase. Mean linear intercept was higher with 0.15 U and 0.2 U of elastase, with destruction of alveolar walls [median (P-25-P75): 30.31 (26.65-43.13) microm and 49.49 (31.67-57.71) microm respectively]. The volume fraction occupied by collagen and elastic fibers was lower in the group receiving 0.2 U of elastase. Conclusion: Four intratracheal instillations of 0.2 U of elastase once a week induced changes in lung function and histology, producing an experimental model of severe pulmonary emphysema, whereas 0.15 U resulted in only histological changes.

Dynamics of chest wall volume regulation during constant work rate exercise in patients with chronic obstructive pulmonary disease

This study evaluated the dynamic behavior of total and compartmental chest wall volumes [(V CW) = rib cage (V RC) + abdomen (V AB)] as measured breath-by-breath by optoelectronic plethysmography during constant-load exercise in patients with stable chronic obstructive pulmonary disease. Thirty males (GOLD stages II-III) underwent a cardiopulmonary exercise test to the limit of tolerance (Tlim) at 75% of peak work rate on an electronically braked cycle ergometer. Exercise-induced dynamic hyperinflation was considered to be present when end-expiratory (EE) V CW increased in relation to resting values. There was a noticeable heterogeneity in the patterns of V CW regulation as EEV CW increased non-linearly in 17/30 "hyperinflators" and decreased in 13/30 "non-hyperinflators" (P < 0.05). EEV AB decreased slightly in 8 of the "hyperinflators", thereby reducing and slowing the rate of increase in end-inspiratory (EI) V CW (P < 0.05). In contrast, decreases in EEV CW in the "non-hyperinflators" were due to the combination of stable EEV RC with marked reductions in EEV AB. These patients showed lower EIV CW and end-exercise dyspnea scores but longer Tlim than their counterparts (P < 0.05). Dyspnea increased and Tlim decreased non-linearly with a faster rate of increase in EIV CW regardless of the presence or absence of dynamic hyperinflation (P < 0.001). However, no significant between-group differences were observed in metabolic, pulmonary gas exchange and cardiovascular responses to exercise. Chest wall volumes are continuously regulated during exercise in order to postpone (or even avoid) their migration to higher operating volumes in patients with COPD, a dynamic process that is strongly dependent on the behavior of the abdominal compartment.

A sigmoidal fit for pressure-volume curves of idiopathic pulmonary fibrosis patients on mechanical ventilation: clinical implications

OBJECTIVE: Respiratory pressure-volume curves fitted to exponential equations have been used to assess disease severity and prognosis in spontaneously breathing patients with idiopathic pulmonary fibrosis. Sigmoidal equations have been used to fit pressure-volume curves for mechanically ventilated patients but not for idiopathic pulmonary fibrosis patients. We compared a sigmoidal model and an exponential model to fit pressure-volume curves from mechanically ventilated patients with idiopathic pulmonary fibrosis. METHODS: Six idiopathic pulmonary fibrosis patients and five controls underwent inflation pressure-volume curves using the constant-flow technique during general anesthesia prior to open lung biopsy or thymectomy. We identified the lower and upper inflection points and fit the curves with an exponential equation, V = A-B.e-k.P, and a sigmoid equation, V = a+b/(1+e-(P-c)/d). RESULTS: The mean lower inflection point for idiopathic pulmonary fibrosis patients was significantly higher (10.5 ± 5.7 cm H2O) than that of controls (3.6 ± 2.4 cm H2O). The sigmoidal equation fit the pressure-volume curves of the fibrotic and control patients well, but the exponential equation fit the data well only when points below 50 percent of the inspiratory capacity were excluded. CONCLUSION: The elevated lower inflection point and the sigmoidal shape of the pressure-volume curves suggest that respiratory system compliance is decreased close to end-expiratory lung volume in idiopathic pulmonary fibrosis patients under general anesthesia and mechanical ventilation. The sigmoidal fit was superior to the exponential fit for inflation pressure-volume curves of anesthetized patients with idiopathic pulmonary fibrosis and could be useful for guiding mechanical ventilation during general anesthesia in this condition.

Effect of prone positioning on oxygenation and lung mechanics in neonates with mechanical ventilation / 中国小儿急救医学

Objective To investigate the effects of prone positioning on oxygenation and lung mechanics in neonates with mechanical ventilation.Methods Twenty cases of neonates,selected from Shanghai Children′s Hospital(from May 2008 to Feb 2009),were randomized to supine-prone position group (n=10) and prone-supine position group (n=10) using a crossover design.During 6h,these neonates were placed in the supine position for 3h then in the prone position for 3h or in reversed order.The ventilator parameters,results of arterial blood gas and the lung mechanics were recorded.Results Without obvious changes of ventilator parameters,PaO2 improved significantly when the incubated neonates were placed in the prone position for 3h compared to supine [(74.50±15.37)mm Hg vs (67.60±13.66)mm Hg,1mm Hg=0.133kPa,P<0.05).Similarly,oxygenation index of prone positioning for 3h was (201.86±55.96)mm Hg,which was higher than that of (184.38±63.58)mm Hg,the value of supine positioning for 3 h.There were significant differences (P<0.05).Our results showed that 60% (12/20) of the neonates responded to prone positioning,with oxysenation index increasing as much as 17mm Hg on average.Improvement in minute volume,tidal volume and dynamic compliance of the lung were achieved after prone positioning for 3h (P=0.011,0.020,0.045).The airway resistance did not decrease significantly (P=0.422),but the average decreased in the prone position.Conclusion Oxygenation and the lung mechanics are improved significantly in the neonates with prone position compared with supine position.

Comparison of the effects of two types of recruitment maneuver used in patients with ARDS / 中华急诊医学杂志

Objective To investigate and compare the effects of sustained inflation (SI) and pressure controlled ventilation (PCV) on lung recruitment in patients with ARDS, and on hemodynamics and respiratory mechanics of patients. Methods Ten patients with ARDS were included in this randomized clinical trial ( RCT), and SI (40 cmH20, 40s) and PCV (20 cmH20, 2 min) were successively applied to each patient under sedation, non-muscle relaxation state. There was a elution period between two types of recruitment maneuver (RM). Parameters of respiratory mechanics, gas exchange and hemodynamics were measured before RM (T0), 5 min after RM (T2) and one hour after RM (T3). Parameters of respiratory mechanics and hemodynamics were measured during the period of RM (Tl). Results (1) The PaO2 at T2 and T3 increased significantly in comparison with that at To ( P < 0.05), and there was no significant difference in PaO2 between two types of RM (P > 0.05). There were no significant differences in PaCO2 between two types of RM at each interval (P > 0.05). (2) The cardiac index ( CI) at T1 decreased significantly compared with that at To in two types of RM (P < 0.05), but there was difference in CI between two types of RM (P > 0.05). There were no differences in MAP and HR at these intervals (P > 0.05). (3) The functional residual capacity (FRC) at T2 and T3 increased significantly in comparison with that at To in two types of RM (P < 0.05). The static compliance (Cs) at T1 improved significantly (P < 0.05), but there was no difference in Cs between two types of RM ( P > 0.05). There was no difference in plateau pressure (Pplat) at all intervals (P >0.05). Conclusions The oxygenation, FRC, and Cs improve significantly in both SI-RM and PCV-RM, and the effects of two types of RM are similar. The SI-RM and PCV-RM have the similar impact on circulatory system during RM.

Estudo tomográfico de pressões de colapso alveolar e níveis isogravitacionais em pulmões de pacientes com SDRA e LPA / Tomographic study of alveolar collapsing pressures and isogravitational levels and in the lungs of patients with ARDS and/or ALI

Estudo clínico prospectivo, em 11 pacientes com SARA ou LPA, avaliando o comportamento regional da densidade do tecido pulmonar e do colapso alveolar ao longo dos três eixos do espaço. Foram realizadas tomografias seriadas, após manobra de recrutamento inicial e após níveis de PEEP progressivamente decrescentes. Regressão linear múltipla (R2=0.83) mostrou importante gradiente no eixo gravitacional (p<0.001) e não no sentido céfalo-caudal (p<0.001), nem da direita para a esquerda (p<0.05). Isto corrobora o conceito do pulmão líquido, em que a resultante das pressões exercidas pelo diafragma, estruturas mediastinais e derrames seria transmitida uniformemente pelo tecido pulmonar. Cada um destes níveis isogravitacionais tem uma pressão crítica de fechamento (Pclosing), que é maior do que a pressão superimposta calculada. PEEP tem um efeito homogeneizador sobre o parênquima pulmonar. Dentre os parâmetros clínicos estudados, Pflex mostrou a pior correlação com colapso pulmonar documentado enquanto PO2 e a complacência máxima se mostraram equivalentes.

A prospective clinical study performed on 11 patients with ARDS or ALI with the intention of studying the regional behavior of lung tissue density and alveolar collapse along the three spatial axes. An initial recruitment maneuver was followed by multiple semi-complete CT scans at descending levels of PEEP. Multiple linear regression (R2=0.83) showed a gravitational gradient of densities and collapse (p<0.001) and no cephalo-caudal (p<0.001) or right-toleft increase (p<0.05), corroborating the liquid-like behavior of the lung. Pressure exerted by mediastinal structures, chest wall and effusions is transmitted uniformly throughout the lung. PEEP has a homogenizing effect on lung parenchyma. Among commonly used clinical surrogates, Pflex showed the worst correlation with actual lung collapse, while arterial PO2 and compliance were equivalent.

Comportamento da mecânica pulmonar após a aplicação de protocolo de fisioterapia respiratória e aspiração traqueal em pacientes com ventilação mecânica invasiva / Behavior of the lung mechanics after the application of protocol of chest physiotherapy and aspiration tracheal in patients with invasive mechanical ventilation

JUSTIFICATIVA E OBJETIVOS: A fisioterapia respiratória (FR) em pacientes submetidos a suporte ventilatório invasivo, atua diretamente no sistema ventilatório podendo alterar a mecânica pulmonar através da complacência pulmonar dinâmica (Cdyn) e da resistência do sistema respiratório (Rsr). Porém, as alterações descritas após a realização de FR permanecem controversas. O objetivo deste estudo foi avaliar as alterações da mecânica pulmonar em pacientes em ventilação mecânica invasiva (VMI). MÉTODO: Foi realizado estudo prospectivo e aleatório, controlado do tipo cruzado, incluindo pacientes com mais de 48 horas em VMI. Os protocolos de fisioterapia respiratória (PF) e de aspiração traqueal isolada (PA) foram aleatorizados para a ordem de aplicação, com intervalo de 24 horas entre eles. Dados da mecânica pulmonar e das variáveis cardiorrespiratórias foram coletados antes da aplicação do protocolo, imediatamente após; 30 minutos e 120 minutos após a aplicação dos protocolos. RESULTADOS: Doze pacientes completaram o estudo. A pneumonia foi a causa mais comum de insuficiência respiratória (IRpA). Não houve diferença estatisticamente significativa entre os grupos em relação à Cdyn, volume de ar corrente (VAC) e volume-minuto (VM). A Rsr diminuiu de forma significativa imediatamente após (de 10,4 ± 3 cmH2O/L/seg para 8,9 ± 2 cmH2O/L/seg; p < 0,02), 30 minutos após (de 10,4 ± 3 cmH2O/L/seg para 9 ± 2 cmH2O/L/seg; p < 0,01) e 120 min após (de 10,4 ± 3 cmH2O/L/seg para 9 ± 2 cmH2O/L/seg; p < 0,03) a aplicação do protocolo de fisioterapia respiratória. Quando comparado com o protocolo de aspiração traqueal isolada foi significativamente menor nos momentos 30 (9 ± 2 cmH2O/L/seg versus 10,2 ± 2 cmH2O/L/seg; p < 0,04) e 120 minutos (9 ± 2 cmH2O/L/segundo versus 10,4 ± 3 cmH2O/L/seg; p < 0,04). CONCLUSÕES: O protocolo de fisioterapia respiratória foi eficaz na diminuição da Rsr quando comparado com o protocolo de aspiração. Essa diminuição manteve-se...

BACKGROUND AND OBJECTIVES: The chest physiotherapy (CP) in patients submitted to invasive support ventilation acts directly in the breathing system, and it could alter the lung mechanics through the dynamic lung compliance (DynC) and resistance of the breathing system (Rbs). However the alterations after the accomplishment of CP are still controversy. The objective of this study was to evaluate the alterations of the lung mechanics in patients in invasive mechanical ventilation (IMV). METHODS: It was a prospective, randomized, and controlled and crossover study, with patient with more than 48 hours in IMV. The protocol of chest physiotherapy and isolated tracheal aspiration they were randomized for the application order with a window of 24 hours among them. Data of lung mechanics and its varied cardiorespiratory were collected moments before the protocol, immediately after the application of the protocol, 30 minutes and 120 minutes after the application of the protocols. RESULTS: Twelve patients completed the study. Pneumonia was the mean cause respiratory failure (RF). There was not statistical difference among the groups in relation to Cdyn, volume tidal (Vt) and volume minute (Ve). Rbs decreased in a significant way immediately after (of 10.4 ± 3 cmH2O/L/seg for 8.9 ± 2 cmH2O/L/seg; p < 0.02), 30 minutes after (of 10.4 ± 3 cmH2O/L/seg for 9 ± 2 cmH2O/L/seg; p < 0.01) and 120 minutes after (of 10.4 ± 3 cmH2O/L/seg for 9 ± 2 cmH2O/L/seg; p < 0.03) application the protocol of chest physiotherapy. When compared with the protocol of isolated tracheal aspiration it was significantly smaller in the 30 (9 ± 2 cmH2O/L/seg versus10.2 ± 2 cmH2O/L/seg; p < 0.04) and 120 minutes (9 ± 2 cmH2O/L/seg versus 10.4 ± 3 cmH2O/L/seg; p < 0.04). CONCLUSIONS: The protocol of chest physiotherapy was effective in the decrease of Rsr when compared with the aspiration protocol. That decrease was maintained for two hours after its application, what did not happen...

The Changes in Lung Mechanics before and after the Nuss Operation in Pectus Excavatum Patients / 대한마취과학회지

BACKGROUND: Nuss et al introduced a less invasive method for inserting a stainless steel bar through the small incision on the lateral chest wall into the pectus excavatum. This study was undertaken to assess the effect of the Nuss operation on lung mechanics, CT-Index and hemodynamics. METHODS: Twenty patients (age 4 to 17 years) with severe pectus excavatum underwent the Nuss operation. CT-Index (the internal transverse distance of the thorax/the vertebral-sternal distance at greatest depression) was evaluated before operation. Lung mechanics (dynamic compliance [Cdyn], static compliance [Cstat] and airway resistance [Raw]), hemodynamic changes (heart rate [HR], systolic blood pressure [SBP], and diastolic blood pressure [DBP]), and gas exchange (arterial oxygen tension [PaO2], arterial carbon dioxide tension [PaCO2], pulse oximeter saturation [SPO2] and end-tidal carbon dioxide tension[PETCO2]) were measured before and after the operation. RESULTS: Cdyn and Cstat decreased significantly (P < 0.05), but Raw did not change. PaCO2 and PETCO2 decreased significantly (P < 0.05), and SBP and DBP increased significantly (P < 0.05) postoperatively. CONCLUSIONS: It is concluded that decreased compliance after the Nuss operation may result from reduced thoracic elastance, not to a change of lung parenchyma.

A Comparison of Pressure Controlled Ventilation and Hybrid Ventilation in Rabbits / 대한마취과학회지

BACKGROUND: Intermittent positive pressure is required to overcome pulmonary airway resistance during inspiration and to deliver an adequate tidal volume. Previous animal experiments have shown that mechanical ventilation may worsen the lung injury when high airway pressure and large tidal volume are required to achieve adequate ventilation and oxygenation. Many ventilatory strategies have been developed to minimize airway pressure increase for the less compliant lung. Intratracheal pulmonary ventilation (ITPV) was developed to allow a decrease in physiological dead space during mechanical ventilation. METHODS: Pressure controlled ventilation (PC) has been compared with hybrid ventilation (HV) which consists of PC and ITPV in 7 rabbits. A reverse thrust catheter (RTC) was introduced into an endotracheal tube (ETT) through an adapter and positioned just above the carina inside the ETT. Fresh gas flowed continuously along the gap between inner cannula and outer cap in the expiratory direction. Gas was intermittently re-directed into the lung as a tidal volume by a valve on the expiratory circuit with ventilatory mode of PC to make HV. Peak inspiratory pressure (PIP) and dead space (VD) at various respiratory rates (RR) of 20/min, 40/min, 80/min and 120/min were compared between PC and HV while maintaining normal PaCO2. RESULTS: The PIPs of PC were 12.4 +/- 3.4 cmH2O, 9.0 +/- 2.7 cmH2O, 8.8 +/- 2.7 cmH2O, and 7.6 +/- 2.5 cmH2O at RR of 20/min, 40/min, 80/min and 120/min, respectively. The PIPs of HV were 9.2 +/- 3.2 cmH2O, 6.2 +/- 1.7 cmH2O, 5.0 +/- 2.0 cmH2O, and 4.5 +/- 1.8 cmH2O at the same RR of 20/min, 40/min, 80/min and 120/min, respectively. The VDS of HV were lower than those of PC. CONCLUSION: It can be concluded that ITPV can be applied as a HV to minimize airway pressure under the setting of PC.