Dynamic inflation prevents and standardized lung recruitment reverts volume loss associated with percutaneous tracheostomy during volume control ventilation: results from a Neuro-ICU population.

To determine how percutaneous tracheostomy (PT) impacts on respiratory system compliance (Crs) and end-expiratory lung volume (EELV) during volume control ventilation and to test whether a recruitment maneuver (RM) at the end of PT may reverse lung derecruitment. This is a single center, prospective, applied physiology study. 25 patients with acute brain injury who underwent PT were studied. Patients were ventilated in volume control ventilation. Electrical impedance tomography (EIT) monitoring and respiratory mechanics measurements were performed in three steps: (a) baseline, (b) after PT, and (c) after a standardized RM (10 sighs of 30 cmH2O lasting 3 s each within 1 min). End-expiratory lung impedance (EELI) was used as a surrogate of EELV. PT determined a significant EELI loss (mean reduction of 432 arbitrary units p = 0.049) leading to a reduction in Crs (55 ± 13 vs. 62 ± 13 mL/cmH2O; p < 0.001) as compared to baseline. RM was able to revert EELI loss and restore Crs (68 ± 15 vs. 55 ± 13 mL/cmH2O; p < 0.001). In a subgroup of patients (N = 8, 31%), we observed a gradual but progressive increase in EELI. In this subgroup, patients did not experience a decrease of Crs after PT as compared to patients without dynamic inflation. Dynamic inflation did not cause hemodynamic impairment nor raising of intracranial pressure. We propose a novel and explorative hyperinflation risk index (HRI) formula. Volume control ventilation did not prevent the PT-induced lung derecruitment. RM could restore the baseline lung volume and mechanics. Dynamic inflation is common during PT, it can be monitored real-time by EIT and anticipated by HRI. The presence of dynamic inflation during PT may prevent lung derecruitment.

Quantitative Computed Tomography and Response to Pronation in COVID-19 ARDS.

BACKGROUND: The use of prone position (PP) has been widespread during the COVID-19 pandemic. Whereas it has demonstrated benefits, including improved oxygenation and lung aeration, the factors influencing the response in terms of gas exchange to PP remain unclear. In particular, the association between baseline quantitative computed tomography (CT) scan results and gas exchange response to PP in invasively ventilated subjects with COVID-19 ARDS is unknown. The present study aimed to compare baseline quantitative CT results between subjects responding to PP in terms of oxygenation or CO2 clearance and those who did not. METHODS: This was a single-center, retrospective observational study including critically ill, invasively ventilated subjects with COVID-19-related ARDS admitted to the ICUs of Niguarda Hospital between March 2020-November 2021. Blood gas samples were collected before and after PP. Subjects in whom the PaO2 /FIO2 increase was ≥ 20 mm Hg after PP were defined as oxygen responders. CO2 responders were defined when the ventilatory ratio (VR) decreased during PP. Automated quantitative CT analyses were performed to obtain tissue mass and density of the lungs. RESULTS: One hundred twenty-five subjects were enrolled, of which 116 (93%) were O2 responders and 51 (41%) CO2 responders. No difference in quantitative CT characteristics and oxygen were observed between responders and non-responders (tissue mass 1,532 ± 396 g vs 1,654 ± 304 g, P = .28; density -544 ± 109 HU vs -562 ± 58 HU P = .42). Similar findings were observed when dividing the population according to CO2 response (tissue mass 1,551 ± 412 g vs 1,534 ± 377 g, P = .89; density -545 ± 123 HU vs -546 ± 94 HU, P = .99). CONCLUSIONS: Most subjects with COVID-19-related ARDS improved their oxygenation at the first pronation cycle. The study suggests that baseline quantitative CT scan data were not associated with the response to PP in oxygenation or CO2 in mechanically ventilated subjects with COVID-19-related ARDS.

Role of hemolysis on pulmonary arterial compliance and right ventricular systolic function after cardiopulmonary bypass.

BACKGROUND: Cardiopulmonary bypass (CPB) is associated with intravascular hemolysis which depletes endogenous nitric oxide (NO). The impact of hemolysis on pulmonary arterial compliance (PAC) and right ventricular systolic function has not been explored yet. We hypothesized that decreased NO availability is associated with worse PAC and right ventricular systolic function after CPB. METHODS: This is a secondary analysis of an observational cohort study in patients undergoing cardiac surgery with CPB at Massachusetts General Hospital, USA (2014-2015). We assessed PAC (stroke volume/pulmonary artery pulse pressure ratio), and right ventricular function index (RVFI) (systolic pulmonary arterial pressure/cardiac output), as well as NO consumption at 15 min, 4 h and 12 h after CPB. Patients were stratified by CPB duration. Further, we assessed the association between changes in NO consumption with PAC and RVFI between 15min and 4 h after CPB. RESULTS: PAC was lowest at 15min after CPB and improved over time (n = 50). RVFI was highest -worse right ventricular function- at CPB end and gradually decreased. Changes in hemolysis, PAC and RVFI differed over time by CPB duration. PAC inversely correlated with total pulmonary resistance (TPR). TPR and PAC positively and negatively correlated with RVFI, respectively. NO consumption between 15min and 4 h after CPB correlated with changes in PAC (-0.28 ml/mmHg, 95%CI -0.49 to -0.01, p = 0.012) and RVFI (0.14 mmHg*L-1*min, 95%CI 0.10 to 0.18, p < 0.001) after multivariable adjustments. CONCLUSION: PAC and RVFI are worse at CPB end and improve over time. Depletion of endogenous NO may contribute to explain changes in PAC and RVFI after CPB.

Successful Versus Failed Transition From Controlled Ventilation to Pressure Support Ventilation in COVID-19 Patients: A Retrospective Cohort Study.

OBJECTIVES: In patients with COVID-19 respiratory failure, controlled mechanical ventilation (CMV) is often necessary during the acute phases of the disease. Weaning from CMV to pressure support ventilation (PSV) is a key objective when the patient's respiratory functions improve. Limited evidence exists regarding the factors predicting a successful transition to PSV and its impact on patient outcomes. DESIGN: Retrospective observational cohort study. SETTING: Twenty-four Italian ICUs from February 2020 to May 2020. PATIENTS: Mechanically ventilated ICU patients with COVID-19-induced respiratory failure. INTERVENTION: The transition period from CMV to PSV was evaluated. We defined it as "failure of assisted breathing" if the patient returned to CMV within the first 72 hours. MEASUREMENTS AND MAIN RESULTS: Of 1260 ICU patients screened, 514 were included. Three hundred fifty-seven patients successfully made the transition to PSV, while 157 failed. Pao2/Fio2 ratio before the transition emerged as an independent predictor of a successful shift (odds ratio 1.00; 95% CI, 0.99-1.00; p = 0.003). Patients in the success group displayed a better trend in Pao2/Fio2, Paco2, plateau and peak pressure, and pH level. Subjects in the failure group exhibited higher ICU mortality (hazard ratio 2.08; 95% CI, 1.42-3.06; p < 0.001), an extended ICU length of stay (successful vs. failure 21 ± 14 vs. 27 ± 17 d; p < 0.001) and a longer duration of mechanical ventilation (19 ± 18 vs. 24 ± 17 d, p = 0.04). CONCLUSIONS: Our study emphasizes that the Pao2/Fio2 ratio was the sole independent factor associated with a failed transition from CMV to PSV. The unsuccessful transition was associated with worse outcomes.

Gas Humidification During Helmet Continuous Positive Airway Pressure: A Crossover Randomized Physiologic Study in Healthy Subjects.

BACKGROUND: In the last decades, the use of the helmet interface to deliver noninvasive respiratory support has steadily increased. When delivering oxygen therapy, conditioning of inspired gas is mandatory, as the water content of medical gas is neglectable. To minimize the risk of airway damage, it is recommended to achieve an absolute humidity greater than 10 mg H2O/L. The primary aim of the study was to assess the performance of 3 different heated humidifiers to condition gas during helmet continuous positive airway pressure and to compare them with a setting without active humidification. METHODS: We performed a crossover randomized physiological study in healthy volunteers. Absolute humidity, relative humidity, and temperature were measured during 4 steps (no humidification and the 3 heated humidifiers, performed in a randomized order) and at 3 time points (after 1, 5, and 10 minutes). RESULTS: Eight subjects participated to the study. Without active humidification, absolute humidity was constantly below the recommended level. All humidifiers conditioned the inspired gases to an average absolute humidity greater than 10 mg H2O/L. Overall, the best performance, in terms of absolute humidity, was obtained with H900 (19.74 ± 0.50 mg H2O/L), followed by TurbH2O (-6.82 mg H2O/L vs H900; 95% confidence interval, -8.49 to -5.14; P < .05) and F&P 810 (-9.03 mg H2O/L vs H900; 95% confidence interval, -10.70 to -7.35; P < .05). CONCLUSIONS: Active humidification is required to achieve adequate conditioning of inspired gas during helmet continuous positive airway pressure. The choice between different humidifiers available on the market should be made according to the local needs and expertise.

Combining the Physical-Chemical Approach with Standard Base Excess to Understand the Compensation of Respiratory Acid-Base Derangements: An Individual Participant Meta-analysis Approach to Data from Multiple Canine and Human Experiments.

BACKGROUND: Several studies explored the interdependence between Paco2 and bicarbonate during respiratory acid-base derangements. The authors aimed to reframe the bicarbonate adaptation to respiratory disorders according to the physical-chemical approach, hypothesizing that (1) bicarbonate concentration during respiratory derangements is associated with strong ion difference; and (2) during acute respiratory disorders, strong ion difference changes are not associated with standard base excess. METHODS: This is an individual participant data meta-analysis from multiple canine and human experiments published up to April 29, 2021. Studies testing the effect of acute or chronic respiratory derangements and reporting the variations of Paco2, bicarbonate, and electrolytes were analyzed. Strong ion difference and standard base excess were calculated. RESULTS: Eleven studies were included. Paco2 ranged between 21 and 142 mmHg, while bicarbonate and strong ion difference ranged between 12.3 and 43.8 mM, and 32.6 and 60.0 mEq/l, respectively. Bicarbonate changes were linearly associated with the strong ion difference variation in acute and chronic respiratory derangement (ß-coefficient, 1.2; 95% CI, 1.2 to 1.3; P < 0.001). In the acute setting, sodium variations justified approximately 80% of strong ion difference change, while a similar percentage of chloride variation was responsible for chronic adaptations. In the acute setting, strong ion difference variation was not associated with standard base excess changes (ß-coefficient, -0.02; 95% CI, -0.11 to 0.07; P = 0.719), while a positive linear association was present in chronic studies (ß-coefficient, 1.04; 95% CI, 0.84 to 1.24; P < 0.001). CONCLUSIONS: The bicarbonate adaptation that follows primary respiratory alterations is associated with variations of strong ion difference. In the acute phase, the variation in strong ion difference is mainly due to sodium variations and is not paralleled by modifications of standard base excess. In the chronic setting, strong ion difference changes are due to chloride variations and are mirrored by standard base excess.

Consideraciones prácticas para el desarrollo de programas de analgesia postoperatoria / Implementation practical aspects of postoperative pain programs

Los programas de analgesia postoperatoria que cuentan con sistemas de registro de dolor, sedación y efectos adversos de los fármacos, utilizados junto al resto de los controles sistemáticos que se realizan en todos los pacientes, mejoran la calidad de atención del postoperatorio. La puesta en práctica de normativas generales implica la adecuación de las normas a la realidad de cada institución, la capacitación y el entrenamiento de todo el personal, la transformación de conductas y hábitos contrarios a las normas, la selección cuidadosa de pacientes y sectores de internación y la evaluación periódica de los resultados. Es claro que la solución a los problemas del manejo del dolor postoperatorio no se encuentran en el desarrollo de nuevas técnicas, sino en la organización y explotación de los recursos existentes. El desarrollo del nuevo proyecto no es dependiente de cuánto se tiene, sino de cuánto se puede hacer con lo que se tiene. El objetivo del presente trabajo es revisar, en base a la experiencia acumulada en nuestros hospitales, los aspectos prácticos de la puesta en funcionamiento de programas de analgesia postoperatoria en el ámbito hospitalario.

Consideraciones prácticas para el desarrollo de programas de analgesia postoperatoria / Implementation practical aspects of postoperative pain programs

Los programas de analgesia postoperatoria que cuentan con sistemas de registro de dolor, sedación y efectos adversos de los fármacos, utilizados junto al resto de los controles sistemáticos que se realizan en todos los pacientes, mejoran la calidad de atención del postoperatorio. La puesta en práctica de normativas generales implica la adecuación de las normas a la realidad de cada institución, la capacitación y el entrenamiento de todo el personal, la transformación de conductas y hábitos contrarios a las normas, la selección cuidadosa de pacientes y sectores de internación y la evaluación periódica de los resultados. Es claro que la solución a los problemas del manejo del dolor postoperatorio no se encuentran en el desarrollo de nuevas técnicas, sino en la organización y explotación de los recursos existentes. El desarrollo del nuevo proyecto no es dependiente de cuánto se tiene, sino de cuánto se puede hacer con lo que se tiene. El objetivo del presente trabajo es revisar, en base a la experiencia acumulada en nuestros hospitales, los aspectos prácticos de la puesta en funcionamiento de programas de analgesia postoperatoria en el ámbito hospitalario. (AU)

Evaluación prospectiva de bloqueos regionales centrales en pediatría: ventajas, desventajas y complicaciones / Prospective evaluation of pediatric central blocks: advantage, disadvantage and complications

Antecedentes: Las técnicas de anestesia regional y combinada en pediatría son utilizadas desde hace años en cirugías de alto impacto aferente o en pacientes con problemas especiales. Objetivo: Evaluación de las ventajas, desventajas y complicaciones de técnicas de anestesia regional y combinada con bloqueos centrales en pediatría. Lugar de aplicación: Servicio de Anestesiología del Hospital Nacional de Pediatría "Prof. Dr. Juan P. Garrahan", Buenos Aires, Argentina. Unità Operativa di Anestesia e Rianimazione III. Terapia Intensiva Pediatrica, Azienda Ospiedaliera "Ospedali Riuniti", Bergamo, Italia. Diseño: case control study. Población: 250 pacientes ASA I a III, menores de 16 años. Método: Selección de pacientes con beneficios teóricos de recibir anestesia regional o combinada, según el tipo de intervención, por el tipo de estimulación quirúrgica o por riesgo potencial frente al uso de anestesia general convencional. Resultados: 100 bloqueos epidurales lumbares o torácicos, 100 caudales, 50 raquídeos. Efectividad: 97 por ciento. Se registraron complicaciones menores en 10 pacientes. Conclusiones: Las técnicas de anestesia regional o combinada en pediatría permiten un excelente nivel de bloqueo aferente, brindando excelentes condiciones quirúrgicas. Presentan múltiples ventajas en cirugía pediátrica con adecuados niveles de seguridad.

Evaluación prospectiva de bloqueos regionales centrales en pediatría: ventajas, desventajas y complicaciones / Prospective evaluation of pediatric central blocks: advantage, disadvantage and complications

Antecedentes: Las técnicas de anestesia regional y combinada en pediatría son utilizadas desde hace años en cirugías de alto impacto aferente o en pacientes con problemas especiales. Objetivo: Evaluación de las ventajas, desventajas y complicaciones de técnicas de anestesia regional y combinada con bloqueos centrales en pediatría. Lugar de aplicación: Servicio de Anestesiología del Hospital Nacional de Pediatría "Prof. Dr. Juan P. Garrahan", Buenos Aires, Argentina. UnitO Operativa di Anestesia e Rianimazione III. Terapia Intensiva Pediatrica, Azienda Ospiedaliera "Ospedali Riuniti", Bergamo, Italia. Diseño: case control study. Población: 250 pacientes ASA I a III, menores de 16 años. Método: Selección de pacientes con beneficios teóricos de recibir anestesia regional o combinada, según el tipo de intervención, por el tipo de estimulación quirúrgica o por riesgo potencial frente al uso de anestesia general convencional. Resultados: 100 bloqueos epidurales lumbares o torácicos, 100 caudales, 50 raquídeos. Efectividad: 97 por ciento. Se registraron complicaciones menores en 10 pacientes. Conclusiones: Las técnicas de anestesia regional o combinada en pediatría permiten un excelente nivel de bloqueo aferente, brindando excelentes condiciones quirúrgicas. Presentan múltiples ventajas en cirugía pediátrica con adecuados niveles de seguridad. (AU)