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Enfoques de ventilación con protección para la ventilación unipulmonar

Artículo

Autor: Munir Karjaghli, especialista en aplicaciones clínicas, Hamilton Medical AG

Fecha: 15.11.2021

El síndrome de dificultad respiratoria aguda (SDRA) y la lesión pulmonar aguda (LPA) suelen ser complicaciones potencialmente mortales tras una extirpación pulmonar importante. En estudios de grandes cohortes, se ha informado de que la incidencia de SDRA y LPA tras una extirpación pulmonar importante oscila del 2 % al 4 % (1-3). Cuando se producen, estas complicaciones se asocian a una tasa de mortalidad de entre el 50 % y el 70 % (1-3).
Enfoques de ventilación con protección para la ventilación unipulmonar

Mensajes importantes

  • El síndrome de dificultad respiratoria aguda (SDRA) y la lesión pulmonar aguda (LPA) suelen ser complicaciones potencialmente mortales tras una extirpación pulmonar importante.
  • La ventilación unipulmonar durante y después de la cirugía torácica aumenta el riesgo de volutrauma, barotrauma, atelectrauma y toxicidad del oxígeno.
  • La implementación de un protocolo de ventilación con protección durante la ventilación unipulmonar que incluya hipercapnia permisiva, volúmenes tidales reducidos, aumento de la presión positiva al final de la espiración, presiones del respirador limitadas y maniobras de reclutamiento puede reducir el riesgo de lesión pulmonar aguda.

Causas de la lesión pulmonar

La ventilación mecánica durante la ventilación unipulmonar tiene tres objetivos: (I) ayudar en la eliminación del dióxido de carbono, (II) mantener la oxigenación y (III) reducir la disfunción pulmonar posoperatoria. Se han llevado a cabo numerosos estudios para determinar la estrategia más adecuada para la ventilación mecánica durante la ventilación unipulmonar. 

Hay muy diversos factores que pueden contribuir a la LPA perioperatoria. La lesión pulmonar se produce a raíz de la tensión mecánica provocada por la hiperinflación, hiperperfusión y reclutamiento/desreclutamiento cíclico, junto con factores proinflamatorios o bioquímicos. En el caso de los pacientes sometidos a cirugía torácica, una teoría de ‘varios resultados' sugiere que una combinación de factores relacionados con la cirugía, la ventilación unipulmonar, enfermedades subyacentes y morbilidades asociadas, el tratamiento anterior y otros acontecimientos sin identificar pueden provocar una mayor susceptibilidad a la LPA (Lytle FT, Brown DR. Appropriate ventilatory settings for thoracic surgery: intraoperative and postoperative. Semin Cardiothorac Vasc Anesth. 2008;12(2):97-108. doi:10.1177/10892532083198694).

La ventilación unipulmonar durante y después de la cirugía torácica aumenta el riesgo de volutrauma, barotrauma, atelectrauma y toxicidad del oxígeno, todas ellas complicaciones graves que causan lesión pulmonar inducida por el respirador (Lohser J. Evidence-based management of one-lung ventilation. Anesthesiol Clin. 2008;26(2):241-v. doi:10.1016/j.anclin.2008.01.0115).

¿Qué es la ventilación unipulmonar con protección?

Existen muy pocos datos que respalden concretamente un enfoque específico del tratamiento de la ventilación unipulmonar en cuanto a resultados clínicos. La definición de lo que se considera ventilación unipulmonar con protección se ve influida principalmente por la opinión de expertos, las pruebas reunidas de la ventilación bipulmonar en pacientes sometidos a cirugía general y un escaso número de ensayos clínicos. Es muy difícil señalar el volumen tidal, por ejemplo, como único factor contribuyente de la lesión pulmonar durante la ventilación unipulmonar. En ningún estudio hasta la fecha se ha demostrado definitivamente ninguna ventaja específica de la ventilación con volumen tidal (Vt) bajo durante la ventilación unipulmonar en ausencia de otras estrategias respiratorias, como la presión positiva al final de la espiración (PEEP) (Blank RS, Colquhoun DA, Durieux ME, et al. Management of One-lung Ventilation: Impact of Tidal Volume on Complications after Thoracic Surgery. Anesthesiology. 2016;124(6):1286-1295. doi:10.1097/ALN.00000000000011006), la limitación de la presión en la vía aérea y las maniobras de reclutamiento. A menos que exista una contraindicación, estos enfoques respiratorios pueden emplearse en todos los pacientes sometidos a intervención torácica, tanto a nivel intraoperatorio como posoperatorio. El reclutamiento y la PEEP, junto con los líquidos, la inflamación, los anestésicos y otras variables desconocidas, contribuyen a la ventilación con protección pulmonar (Slinger PD. Do Low Tidal Volumes Decrease Lung Injury During One-Lung Ventilation? J Cardiothorac Vasc Anesth. 2017;31(5):1774-1775. doi:10.1053/j.jvca.2017.07.0057). Sin una PEEP adecuada, un Vt bajo durante la ventilación unipulmonar puede causar atelectasia y, en consecuencia, contribuir a un mayor riesgo de morbilidad (Levin MA, McCormick PJ, Lin HM, Hosseinian L, Fischer GW. Low intraoperative tidal volume ventilation with minimal PEEP is associated with increased mortality. Br J Anaesth. 2014;113(1):97-108. doi:10.1093/bja/aeu0548). Una PEEP baja puede ser insuficiente para estabilizar los alvéolos, reducir el esfuerzo alveolar y evitar la atelectasia en los pacientes. Si bien la atelectasia es una preocupación en todos los pacientes sometidos a una intervención quirúrgica con anestesia, puede ser más grave durante la ventilación unipulmonar debido al uso de fracciones de oxígeno inspiratorio más altas (atelectasia por absorción) y al aumento del riesgo de compresión pulmonar dependiente (atelectasia por compresión) (Duggan M, Kavanagh BP. Pulmonary atelectasis: a pathogenic perioperative entity. Anesthesiology. 2005;102(4):838-854. doi:10.1097/00000542-200504000-000219).

¿Presión de trabajo sobre volumen tidal?

En un estudio retrospectivo llevado a cabo después de implementar un protocolo de ventilación con protección durante la ventilación unipulmonar para cirugía de cáncer de pulmón, en el que se incluyó un Vt reducido, aumento de la PEEP, presiones del respirador limitadas y maniobras de reclutamiento, se descubrió menor riesgo de lesión pulmonar aguda (Licker M, Diaper J, Villiger Y, et al. Impact of intraoperative lung-protective interventions in patients undergoing lung cancer surgery. Crit Care. 2009;13(2):R41. doi:10.1186/cc776210). Si bien se desconoce la repercusión exacta del Vt, las nuevas pruebas disponibles indican que la presión de trabajo en las vías aéreas, más que el Vt o la PEEP, es un posible indicador del riesgo de complicación pulmonar posoperatoria y la aplicación de ventilación guiada por la presión de trabajo durante la ventilación unipulmonar se ha relacionado con una menor incidencia de complicaciones pulmonares posoperatorias en comparación con la ventilación con protección convencional en la cirugía torácica (Park M, Ahn HJ, Kim JA, et al. Driving Pressure during Thoracic Surgery: A Randomized Clinical Trial. Anesthesiology. 2019;130(3):385-393. doi:10.1097/ALN.000000000000260011).

Directrices prácticas para el manejo de la ventilación mecánica durante la ventilación unipulmonar

La Society for Translational Medicine presenta recomendaciones basadas en las pruebas actuales para la ventilación unipulmonar en sus directrices de práctica clínica para el manejo de la ventilación mecánica en pacientes sometidos a lobectomía (Gao S, Zhang Z, Brunelli A, et al. The Society for Translational Medicine: clinical practice guidelines for mechanical ventilation management for patients undergoing lobectomy. J Thorac Dis. 2017;9(9):3246-3254. doi:10.21037/jtd.2017.08.16612).

  • La hipercapnia permisiva/terapéutica para mantener una presión parcial de dióxido de carbono entre 50 y 70 mmHg podría ser beneficiosa en pacientes sometidos a ventilación unipulmonar durante operaciones de lobectomía pulmonar.
  • La ventilación con protección con volúmenes tidales entre 4 y 6 ml/kg y una PEEP entre 5 y 8 cmH2O mientras se trata de mantener una presión de trabajo <15 cmH2O parece ser razonable según las pruebas actuales.
  • El reclutamiento alveolar (ventilación a pulmón abierto) podría ser beneficioso en pacientes sometidos a lobectomía con ventilación unipulmonar.
  • Se recomienda la ventilación controlada por presión (CMV-PC) o la ventilación con volumen garantizado controlada por presión (CMV-vtPC) sobre la ventilación controlada por volumen (CMV-VC), y pueden emplearse en pacientes sometidos a extirpación pulmonar con ventilación unipulmonar.
  • Es razonable la aplicación de la FiO2 más baja necesaria para mantener una saturación de oxígeno arterial satisfactoria.
  • La ventilación mecánica controlada con una relación I:E de 1:1 o superior es lógica en pacientes sometidos a ventilación unipulmonar.

El modo de ventilación asistida adaptable (ASV®) en todos los respiradores de Hamilton Medical implementa automáticamente una estrategia de protección pulmonar que cumple las recomendaciones de volumen tidal y presión de trabajo en la ventilación unipulmonar. Además, el modo de bucle completamente cerrado INTELLiVENT®-ASV (No disponible en EE. UU. y otros mercadosA) ofrece la opción de implementar automáticamente la hipercapnia permisiva y de aplicar la FiO2 más baja necesaria para mantener una saturación de oxígeno arterial satisfactoria.

En un estudio de Weiler et al. se revela que la ASV puede suministrar ventilación a los pacientes de forma segura, incluso bajo las condiciones tan variables de la ventilación unipulmonar (Weiler N, Eberle B, Heinrichs W. Adaptive lung ventilation (ALV) during anesthesia for pulmonary surgery: automatic response to transitions to and from one-lung ventilation. J Clin Monit Comput. 1998;14(4):245-252. doi:10.1023/a:100997482523713).

En las figuras 1 y 2 siguientes se muestra un paciente masculino de 61 años con ventilación ASV que se sometió a una neumonectomía derecha.


Puede consultar las citas completas a continuación: (Ruffini E, Parola A, Papalia E, et al. Frequency and mortality of acute lung injury and acute respiratory distress syndrome after pulmonary resection for bronchogenic carcinoma. Eur J Cardiothorac Surg. 2001;20(1):30-37. doi:10.1016/s1010-7940(01)00760-61, Kutlu CA, Williams EA, Evans TW, Pastorino U, Goldstraw P. Acute lung injury and acute respiratory distress syndrome after pulmonary resection. Ann Thorac Surg. 2000;69(2):376-380. doi:10.1016/s0003-4975(99)01090-52, Shapiro M, Swanson SJ, Wright CD, et al. Predictors of major morbidity and mortality after pneumonectomy utilizing the Society for Thoracic Surgeons General Thoracic Surgery Database. Ann Thorac Surg. 2010;90(3):927-935. doi:10.1016/j.athoracsur.2010.05.0413) 

Pantalla donde se muestra un pulmón dinámico y un gráfico ASV
Figura 1
Pantalla donde se muestra un pulmón dinámico y un gráfico ASV
Figura 1
Pantalla con todos los parámetros de monitorización
Figura 2
Pantalla con todos los parámetros de monitorización
Figura 2

Notas al pie

  • A. No disponible en EE. UU. y otros mercados

Referencias

  1. 1. Ruffini E, Parola A, Papalia E, et al. Frequency and mortality of acute lung injury and acute respiratory distress syndrome after pulmonary resection for bronchogenic carcinoma. Eur J Cardiothorac Surg. 2001;20(1):30-37. doi:10.1016/s1010-7940(01)00760-6
  2. 2. Kutlu CA, Williams EA, Evans TW, Pastorino U, Goldstraw P. Acute lung injury and acute respiratory distress syndrome after pulmonary resection. Ann Thorac Surg. 2000;69(2):376-380. doi:10.1016/s0003-4975(99)01090-5
  3. 3. Shapiro M, Swanson SJ, Wright CD, et al. Predictors of major morbidity and mortality after pneumonectomy utilizing the Society for Thoracic Surgeons General Thoracic Surgery Database. Ann Thorac Surg. 2010;90(3):927-935. doi:10.1016/j.athoracsur.2010.05.041
  4. 4. Lytle FT, Brown DR. Appropriate ventilatory settings for thoracic surgery: intraoperative and postoperative. Semin Cardiothorac Vasc Anesth. 2008;12(2):97-108. doi:10.1177/1089253208319869
  5. 5. Lohser J. Evidence-based management of one-lung ventilation. Anesthesiol Clin. 2008;26(2):241-v. doi:10.1016/j.anclin.2008.01.011
  6. 6. Blank RS, Colquhoun DA, Durieux ME, et al. Management of One-lung Ventilation: Impact of Tidal Volume on Complications after Thoracic Surgery. Anesthesiology. 2016;124(6):1286-1295. doi:10.1097/ALN.0000000000001100
  7. 7. Slinger PD. Do Low Tidal Volumes Decrease Lung Injury During One-Lung Ventilation?. J Cardiothorac Vasc Anesth. 2017;31(5):1774-1775. doi:10.1053/j.jvca.2017.07.005
  8. 8. Levin MA, McCormick PJ, Lin HM, Hosseinian L, Fischer GW. Low intraoperative tidal volume ventilation with minimal PEEP is associated with increased mortality. Br J Anaesth. 2014;113(1):97-108. doi:10.1093/bja/aeu054
  9. 9. Duggan M, Kavanagh BP. Pulmonary atelectasis: a pathogenic perioperative entity. Anesthesiology. 2005;102(4):838-854. doi:10.1097/00000542-200504000-00021
  10. 10. Licker M, Diaper J, Villiger Y, et al. Impact of intraoperative lung-protective interventions in patients undergoing lung cancer surgery. Crit Care. 2009;13(2):R41. doi:10.1186/cc7762
  11. 11. Park M, Ahn HJ, Kim JA, et al. Driving Pressure during Thoracic Surgery: A Randomized Clinical Trial. Anesthesiology. 2019;130(3):385-393. doi:10.1097/ALN.0000000000002600
  12. 12. Gao S, Zhang Z, Brunelli A, et al. The Society for Translational Medicine: clinical practice guidelines for mechanical ventilation management for patients undergoing lobectomy. J Thorac Dis. 2017;9(9):3246-3254. doi:10.21037/jtd.2017.08.166
  13. 13. Weiler N, Eberle B, Heinrichs W. Adaptive lung ventilation (ALV) during anesthesia for pulmonary surgery: automatic response to transitions to and from one-lung ventilation. J Clin Monit Comput. 1998;14(4):245-252. doi:10.1023/a:1009974825237

Frequency and mortality of acute lung injury and acute respiratory distress syndrome after pulmonary resection for bronchogenic carcinoma.

Ruffini E, Parola A, Papalia E, et al. Frequency and mortality of acute lung injury and acute respiratory distress syndrome after pulmonary resection for bronchogenic carcinoma. Eur J Cardiothorac Surg. 2001;20(1):30-37. doi:10.1016/s1010-7940(01)00760-6



OBJECTIVE

We reviewed the frequency and mortality of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) in our population of patients submitted to pulmonary resection for primary bronchogenic carcinoma.

METHODS

From January 1993 to December 1999, a total of 1221 patients received pulmonary resection for primary bronchogenic carcinoma. Of these, 27 met the criteria of post-operative ALI/ARDS. There were 24 men and three women with a mean age of 64 years (range 45--79). Pre-operatively, predicted mean of PaO(2), PaCO(2) and %FEV1 were 72 mmHg (57--86), 37 mmHg (33--42) and 80% (37--114), respectively. Associated cardiac risk factors were present in eight patients. Three patients (11%) had pre-operative radiotherapy. Surgical-pathologic staging included 14 patients at Stage I, 8 patients at Stage II, four patients at Stage IIIa and one patient at Stage IIIb.

RESULTS

ALI/ARDS occurred in 2.2% of our operated lung cancer patients. ALI was diagnosed in 10 patients and ARDS in 17 patients. The mean time of presentation following surgery was 4 days (range 1--10) and 6 days (1--13) for ALI and ARDS, respectively. According to the type of operation, the frequency was highest following right pneumonectomy (4.5%), followed by sublobar resection (3.2%), left pneumonectomy (3%), bilobectomy (2.4%), and lobectomy (2%). The frequency following extended operations was 4%. No differences were found between the ALI/ARDS group and the total population of resected lung cancer patients (control group) with respect to sex, mean age, pre-operative blood gases, %FEV1, surgical--pathologic staging and the use of pre-operative radiotherapy. Four patients with ALI (40%) and 10 patients with ARDS (59%) died. Mortality was highest following right pneumonectomy, extended operations and sublobar resections. Hospital mortality of the total population of operated lung cancer patients in the same period was 2.8% (34 patients). ALI/ARDS accounted for 41% of our hospital mortality.

CONCLUSIONS

(1) ALI/ARDS is a severe complication following resection for primary bronchogenic carcinoma. (2) We did not detect any significant difference between the ALI/ARDS group and the control group regarding age, pre-operative lung function, staging and pre-operative radiotherapy. (3) ALI/ARDS is associated with high mortality, the highest mortality rates having been observed following right pneumonectomy and extended operation; it currently represents our leading cause of death following pulmonary resection for lung carcinoma. (4) ALI/ARDS may also occur after sublobar resections with an associated high mortality rate.

Acute lung injury and acute respiratory distress syndrome after pulmonary resection.

Kutlu CA, Williams EA, Evans TW, Pastorino U, Goldstraw P. Acute lung injury and acute respiratory distress syndrome after pulmonary resection. Ann Thorac Surg. 2000;69(2):376-380. doi:10.1016/s0003-4975(99)01090-5



BACKGROUND

In this study we investigate the frequency and mortality of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) after pulmonary resection.

METHODS

Patients that underwent pulmonary resection at the Royal Brompton Hospital between 1991 and 1997 were included. The case notes of all patients developing postoperative complications were retrospectively reviewed.

RESULTS

The overall combined frequency of ALI and ARDS was 3.9%. The frequency was higher in patients over 60 years of age, males and those undergoing resection for lung cancer. ALI/ARDS caused 72.5% of the total mortality after resection in this series.

CONCLUSIONS

In our experience ALI and ARDS are major causes of mortality after lung resection.

Predictors of major morbidity and mortality after pneumonectomy utilizing the Society for Thoracic Surgeons General Thoracic Surgery Database.

Shapiro M, Swanson SJ, Wright CD, et al. Predictors of major morbidity and mortality after pneumonectomy utilizing the Society for Thoracic Surgeons General Thoracic Surgery Database. Ann Thorac Surg. 2010;90(3):927-935. doi:10.1016/j.athoracsur.2010.05.041



BACKGROUND

Pneumonectomy is associated with a significant incidence of perioperative morbidity and mortality. The purpose of this study is to identify the risk factors responsible for adverse outcomes in patients after pneumonectomy utilizing The Society of Thoracic Surgeons General Thoracic Surgery Database (STS GTDB).

METHODS

All patients who had undergone pneumonectomy between January 2002 and December 2007 were identified in the STS GTDB. Among 80 participating centers, 1,267 patients were selected. Logistic regression analysis was performed on preoperative variables for major adverse outcomes.

RESULTS

The rate of major adverse perioperative events was 30.4%, including 71 patients who died (5.6%). Major morbidity was defined as pneumonia, adult respiratory distress syndrome, empyema, sepsis, bronchopleural fistula, pulmonary embolism, ventilatory support beyond 48 hours, reintubation, tracheostomy, atrial or ventricular arrhythmias requiring treatment, myocardial infarct, reoperation for bleeding, and central neurologic event. Patients with major morbidity had a longer mean length of stay compared with patients without major morbidity (13.3 versus 6.1 days, p < 0.001). Independent predictors of major adverse outcomes were age 65 years or older (p < 0.001), male sex (p = 0.026), congestive heart failure (p = 0.04), forced expiratory volume in 1 second less than 60% of predicted (p = 0.01), benign lung disease (p = 0.006), and requiring extrapleural pneumonectomy (p = 0.018). Among patients with lung carcinoma, those receiving neoadjuvant chemoradiotherapy were more at risk for major morbidity than patients without induction therapy (p = 0.049).

CONCLUSIONS

The mortality rate after pneumonectomy by thoracic surgeons participating in the STS database compares favorably to that in previously published studies. We identified risk factors for major adverse outcomes in patients undergoing pneumonectomy.

Appropriate ventilatory settings for thoracic surgery: intraoperative and postoperative.

Lytle FT, Brown DR. Appropriate ventilatory settings for thoracic surgery: intraoperative and postoperative. Semin Cardiothorac Vasc Anesth. 2008;12(2):97-108. doi:10.1177/1089253208319869

Mechanical ventilation of patients undergoing thoracic surgery is often challenging. These patients frequently have significant underlying comorbidities, including cardiopulmonary disease, and often must undergo 1-lung ventilation. Perioperative respiratory complications are common and are multifactorial in etiology. Increasing evidence suggests that mechanical ventilation is associated with, and may even cause, lung damage in both sick and healthy patients. Gas exchange to provide acceptable end-organ oxygenation remains a primary goal but so too is minimization of risks for acute lung injury. Every ventilator strategy is associated with potential beneficial and adverse side effects. Understanding the impact of various ventilation strategies allows clinicians to provide optimal care for patients.

Evidence-based management of one-lung ventilation.

Lohser J. Evidence-based management of one-lung ventilation. Anesthesiol Clin. 2008;26(2):241-v. doi:10.1016/j.anclin.2008.01.011

One-lung ventilation (OLV) is essential for many thoracic and an increasing number of non-thoracic minimally invasive procedures. Beyond the well-recognized disturbance of ventilation-perfusion matching, recent years have seen a mounting body of evidence implicating OLV in the creation of acute lung injury. After reviewing the fundamentals of OLV physiology, this article examines the evidence for altering individual ventilatory parameters toward protective OLV.

Management of One-lung Ventilation: Impact of Tidal Volume on Complications after Thoracic Surgery.

Blank RS, Colquhoun DA, Durieux ME, et al. Management of One-lung Ventilation: Impact of Tidal Volume on Complications after Thoracic Surgery. Anesthesiology. 2016;124(6):1286-1295. doi:10.1097/ALN.0000000000001100



BACKGROUND

The use of lung-protective ventilation (LPV) strategies may minimize iatrogenic lung injury in surgical patients. However, the identification of an ideal LPV strategy, particularly during one-lung ventilation (OLV), remains elusive. This study examines the role of ventilator management during OLV and its impact on clinical outcomes.

METHODS

Data were retrospectively collected from the hospital electronic medical record and the Society of Thoracic Surgery database for subjects undergoing thoracic surgery with OLV between 2012 and 2014. Mean tidal volume (VT) during two-lung ventilation and OLV and ventilator driving pressure (ΔP) (plateau pressure - positive end-expiratory pressure [PEEP]) were analyzed for the 1,019 cases that met the inclusion criteria. Associations between ventilator parameters and clinical outcomes were examined by multivariate linear regression.

RESULTS

After the initiation of OLV, 73.3, 43.3, 18.8, and 7.2% of patients received VT greater than 5, 6, 7, and 8 ml/kg predicted body weight, respectively. One hundred and eighty-four primary and 288 secondary outcome events were recorded. In multivariate logistic regression modeling, VT was inversely related to the incidence of respiratory complications (odds ratio, 0.837; 95% CI, 0.729 to 0.958), while ΔP predicted the development of major morbidity when modeled with VT (odds ratio, 1.034; 95% CI, 1.001 to 1.068).

CONCLUSIONS

Low VT per se (i.e., in the absence of sufficient PEEP) has not been unambiguously demonstrated to be beneficial. The authors found that a large proportion of patients continue to receive high VT during OLV and that VT was inversely related to the incidence of respiratory complications and major postoperative morbidity. While low (physiologically appropriate) VT is an important component of an LPV strategy for surgical patients during OLV, current evidence suggests that, without adequate PEEP, low VT does not prevent postoperative respiratory complications. Thus, use of physiologic VT may represent a necessary, but not independently sufficient, component of LPV.

Do Low Tidal Volumes Decrease Lung Injury During One-Lung Ventilation?

Slinger PD. Do Low Tidal Volumes Decrease Lung Injury During One-Lung Ventilation?. J Cardiothorac Vasc Anesth. 2017;31(5):1774-1775. doi:10.1053/j.jvca.2017.07.005

Low intraoperative tidal volume ventilation with minimal PEEP is associated with increased mortality.

Levin MA, McCormick PJ, Lin HM, Hosseinian L, Fischer GW. Low intraoperative tidal volume ventilation with minimal PEEP is associated with increased mortality. Br J Anaesth. 2014;113(1):97-108. doi:10.1093/bja/aeu054



BACKGROUND

Anaesthetists have traditionally ventilated patients' lungs with tidal volumes (TVs) between 10 and 15 ml kg(-1) of ideal body weight (IBW), without the use of PEEP. Over the past decade, influenced by the results of the Acute Respiratory Distress Syndrome Network trial, many anaesthetists have begun using lower TVs during surgery. It is unclear whether the benefits of low TV ventilation can be extended into the perioperative period.

METHODS

We reviewed the records of 29 343 patients who underwent general anaesthesia with mechanical ventilation between January 1, 2008 and December 31, 2011. We calculated TV kg(-1) IBW, PEEP, peak inspiratory pressure (PIP), and dynamic compliance. Cox regression analysis with propensity score matching was performed to examine the association between TV and 30-day mortality.

RESULTS

Median TV was 8.6 [7.7-9.6] ml kg(-1) IBW with minimal PEEP [4.0 (2.2-5.0) cm H2O]. A significant reduction in TV occurred over the study period, from 9 ml kg(-1) IBW in 2008 to 8.3 ml kg(-1) IBW in 2011 (P=0.01). Low TV 6-8 ml kg(-1) IBW was associated with a significant increase in 30-day mortality vs TV 8-10 ml kg(-1) IBW: hazard ratio (HR) 1.6 [95% confidence interval (CI) [1.25-2.08], P=0.0002]. The association remained significant after matching: HR 1.63 [95% CI (1.22-2.18), P<0.001]. There was only a weak correlation between TV kg(-1) IBW and dynamic compliance (r=-0.006, P=0.31) and a weak-to-moderate correlation between TV kg(-1) IBW and PIP (r=0.32 P<0.0001).

CONCLUSIONS

Use of low intraoperative TV with minimal PEEP is associated with an increased risk of 30-day mortality.

Pulmonary atelectasis: a pathogenic perioperative entity.

Duggan M, Kavanagh BP. Pulmonary atelectasis: a pathogenic perioperative entity. Anesthesiology. 2005;102(4):838-854. doi:10.1097/00000542-200504000-00021

Atelectasis occurs in the dependent parts of the lungs of most patients who are anesthetized. Development of atelectasis is associated with decreased lung compliance, impairment of oxygenation, increased pulmonary vascular resistance, and development of lung injury. The adverse effects of atelectasis persist into the postoperative period and can impact patient recovery. This review article focuses on the causes, nature, and diagnosis of atelectasis. The authors discuss the effects and implications of atelectasis in the perioperative period and illustrate how preventive measures may impact outcome. In addition, they examine the impact of atelectasis and its prevention in acute lung injury.

Impact of intraoperative lung-protective interventions in patients undergoing lung cancer surgery.

Licker M, Diaper J, Villiger Y, et al. Impact of intraoperative lung-protective interventions in patients undergoing lung cancer surgery. Crit Care. 2009;13(2):R41. doi:10.1186/cc7762



INTRODUCTION

In lung cancer surgery, large tidal volume and elevated inspiratory pressure are known risk factors of acute lung (ALI). Mechanical ventilation with low tidal volume has been shown to attenuate lung injuries in critically ill patients. In the current study, we assessed the impact of a protective lung ventilation (PLV) protocol in patients undergoing lung cancer resection.

METHODS

We performed a secondary analysis of an observational cohort. Demographic, surgical, clinical and outcome data were prospectively collected over a 10-year period. The PLV protocol consisted of small tidal volume, limiting maximal pressure ventilation and adding end-expiratory positive pressure along with recruitment maneuvers. Multivariate analysis with logistic regression was performed and data were compared before and after implementation of the PLV protocol: from 1998 to 2003 (historical group, n = 533) and from 2003 to 2008 (protocol group, n = 558).

RESULTS

Baseline patient characteristics were similar in the two cohorts, except for a higher cardiovascular risk profile in the intervention group. During one-lung ventilation, protocol-managed patients had lower tidal volume (5.3 +/- 1.1 vs. 7.1 +/- 1.2 ml/kg in historical controls, P = 0.013) and higher dynamic compliance (45 +/- 8 vs. 32 +/- 7 ml/cmH2O, P = 0.011). After implementing PLV, there was a decreased incidence of acute lung injury (from 3.7% to 0.9%, P < 0.01) and atelectasis (from 8.8 to 5.0, P = 0.018), fewer admissions to the intensive care unit (from 9.4% vs. 2.5%, P < 0.001) and shorter hospital stay (from 14.5 +/- 3.3 vs. 11.8 +/- 4.1, P < 0.01). When adjusted for baseline characteristics, implementation of the open-lung protocol was associated with a reduced risk of acute lung injury (adjusted odds ratio of 0.34 with 95% confidence interval of 0.23 to 0.75; P = 0.002).

CONCLUSIONS

Implementing an intraoperative PLV protocol in patients undergoing lung cancer resection was associated with improved postoperative respiratory outcomes as evidence by significantly reduced incidences of acute lung injury and atelectasis along with reduced utilization of intensive care unit resources.

Driving Pressure during Thoracic Surgery: A Randomized Clinical Trial.

Park M, Ahn HJ, Kim JA, et al. Driving Pressure during Thoracic Surgery: A Randomized Clinical Trial. Anesthesiology. 2019;130(3):385-393. doi:10.1097/ALN.0000000000002600



WHAT WE ALREADY KNOW ABOUT THIS TOPIC

Driving pressure (plateau minus end-expiratory airway pressure) is a target in patients with acute respiratory distress syndrome, and is proposed as a target during general anesthesia for patients with normal lungs. It has not been reported for thoracic anesthesia where isolated, inflated lungs may be especially at risk.

WHAT THIS ARTICLE TELLS US THAT IS NEW

In a double-blinded, randomized trial (292 patients), minimized driving pressure compared with standard protective ventilation was associated with less postoperative pneumonia or acute respiratory distress syndrome.

BACKGROUND

Recently, several retrospective studies have suggested that pulmonary complication is related with driving pressure more than any other ventilatory parameter. Thus, the authors compared driving pressure-guided ventilation with conventional protective ventilation in thoracic surgery, where lung protection is of the utmost importance. The authors hypothesized that driving pressure-guided ventilation decreases postoperative pulmonary complications more than conventional protective ventilation.

METHODS

In this double-blind, randomized, controlled study, 292 patients scheduled for elective thoracic surgery were included in the analysis. The protective ventilation group (n = 147) received conventional protective ventilation during one-lung ventilation: tidal volume 6 ml/kg of ideal body weight, positive end-expiratory pressure (PEEP) 5 cm H2O, and recruitment maneuver. The driving pressure group (n = 145) received the same tidal volume and recruitment, but with individualized PEEP which produces the lowest driving pressure (plateau pressure-PEEP) during one-lung ventilation. The primary outcome was postoperative pulmonary complications based on the Melbourne Group Scale (at least 4) until postoperative day 3.

RESULTS

Melbourne Group Scale of at least 4 occurred in 8 of 145 patients (5.5%) in the driving pressure group, as compared with 18 of 147 (12.2%) in the protective ventilation group (P = 0.047, odds ratio 0.42; 95% CI, 0.18 to 0.99). The number of patients who developed pneumonia or acute respiratory distress syndrome was less in the driving pressure group than in the protective ventilation group (10/145 [6.9%] vs. 22/147 [15.0%], P = 0.028, odds ratio 0.42; 95% CI, 0.19 to 0.92).

CONCLUSIONS

Application of driving pressure-guided ventilation during one-lung ventilation was associated with a lower incidence of postoperative pulmonary complications compared with conventional protective ventilation in thoracic surgery.

The Society for Translational Medicine: clinical practice guidelines for mechanical ventilation management for patients undergoing lobectomy.

Gao S, Zhang Z, Brunelli A, et al. The Society for Translational Medicine: clinical practice guidelines for mechanical ventilation management for patients undergoing lobectomy. J Thorac Dis. 2017;9(9):3246-3254. doi:10.21037/jtd.2017.08.166

Patients undergoing lobectomy are at significantly increased risk of lung injury. One-lung ventilation is the most commonly used technique to maintain ventilation and oxygenation during the operation. It is a challenge to choose an appropriate mechanical ventilation strategy to minimize the lung injury and other adverse clinical outcomes. In order to understand the available evidence, a systematic review was conducted including the following topics: (I) protective ventilation (PV); (II) mode of mechanical ventilation [e.g., volume controlled (VCV) versus pressure controlled (PCV)]; (III) use of therapeutic hypercapnia; (IV) use of alveolar recruitment (open-lung) strategy; (V) pre-and post-operative application of positive end expiratory pressure (PEEP); (VI) Inspired Oxygen concentration; (VII) Non-intubated thoracoscopic lobectomy; and (VIII) adjuvant pharmacologic options. The recommendations of class II are non-intubated thoracoscopic lobectomy may be an alternative to conventional one-lung ventilation in selected patients. The recommendations of class IIa are: (I) Therapeutic hypercapnia to maintain a partial pressure of carbon dioxide at 50-70 mmHg is reasonable for patients undergoing pulmonary lobectomy with one-lung ventilation; (II) PV with a tidal volume of 6 mL/kg and PEEP of 5 cmH2O are reasonable methods, based on current evidence; (III) alveolar recruitment [open lung ventilation (OLV)] may be beneficial in patients undergoing lobectomy with one-lung ventilation; (IV) PCV is recommended over VCV for patients undergoing lung resection; (V) pre- and post-operative CPAP can improve short-term oxygenation in patients undergoing lobectomy with one-lung ventilation; (VI) controlled mechanical ventilation with I:E ratio of 1:1 is reasonable in patients undergoing one-lung ventilation; (VII) use of lowest inspired oxygen concentration to maintain satisfactory arterial oxygen saturation is reasonable based on physiologic principles; (VIII) Adjuvant drugs such as nebulized budesonide, intravenous sivelestat and ulinastatin are reasonable and can be used to attenuate inflammatory response.

Adaptive lung ventilation (ALV) during anesthesia for pulmonary surgery: automatic response to transitions to and from one-lung ventilation.

Weiler N, Eberle B, Heinrichs W. Adaptive lung ventilation (ALV) during anesthesia for pulmonary surgery: automatic response to transitions to and from one-lung ventilation. J Clin Monit Comput. 1998;14(4):245-252. doi:10.1023/a:1009974825237



UNLABELLED

Adaptive lung ventilation is a novel closed-loop-controlled ventilation system. Based upon instantaneous breath-to-breath analyses, the ALV controller adjusts ventilation patterns automatically to momentary respiratory mechanics. Its goal is to provide a preset alveolar ventilation (V'A) and, at the same time, minimize the work of breathing. Aims of our study were (1) to investigate changes in respiratory mechanics during transition to and from one-lung ventilation (OLV), (2) to describe the automated adaptation of the ventilatory pattern.

METHODS

With institutional approval and informed consent, 9 patients (33-72 y, 66-88 kg) underwent ALV during total intravenous anesthesia for pulmonary surgery. The ALV controller uses a pressure controlled ventilation mode. V'A is preset by the anesthesiologist. Flow, pressure, and CO2 are continuously measured at the DLT connector. The signals were read into a IBM compatible PC and processed using a linear one-compartment model of the lung to calculate breath-by-breath resistance (R), compliance (C), respiratory time constant (TC), serial dead space (VdS) and V'A. Based upon the results, the controller optimizes respiratory rate (RR) and tidal volume (VT) such as to achieve the preset V'A with the minimum work of breathing. In addition to V'A, only PEEP and FIO2 settings are at the anesthesiologist's discretion. All patients were ventilated using FIO2 = 1,0 and PEEP = 3 cm H2O. Parameters of respiratory mechanics, ventilation, and ABG were recorded during three 5-min periods: 10 min prior to OLV (1), 20 min after onset of OLV (II), and after chest closure (III). Data analyses used nonparametric comparisons of paired samples (Wilcoxon, Friedman) with Bonferroni's correction. Significance was assumed at p < 0.05. Values are given as medians (range).

RESULTS

20 min after onset of OLV (II), resistance had approximately doubled compared with (1), compliance had decreased from 54 (36-81) to 50 (25-70) ml/cm H2O. TC remained stable at 1.4 (0.8-2.4) vs. 1.2 (0.9)-1.6) s. Institution of OLV was followed by a reproducible response of the ALV controller. The sudden changes in respiratory mechanics caused a transient reduction in VT by 42 (8-59)%, with RR unaffected. In order to reestablish the preset V'A, the controller increased inspiratory pressure in a stepwise fashion from 18 (14-23) to 27 (19-39) cm H2O, thereby increasing VT close to baseline (7.5 (6.6-9.0) ml/kg BW vs. 7.9 (5.4-11.7) ml/kg BW). The controller was, thus, effective in maintaining V'A. The minimum PaO2 during phase II was 101 mmHg. After chest closure, respiratory mechanics had returned to baseline.

CONCLUSIONS

Respiratory mechanics during transition to and from OLV are characterized by marked changes in R and C into opposite directions, leaving TC unaffected. The ALV controller manages these transitions successfully, and maintains V'A reliably without intervention by the anesthesiologist. VT during OLV was found to be consistently lower than recommended in the literature.