Corrigendum: Intraoperative protective mechanical ventilation in dogs: A randomized clinical trial.

[This corrects the article DOI: 10.3389/fvets.2022.842613.].

Intraoperative Protective Mechanical Ventilation in Dogs: A Randomized Clinical Trial.

Objective: To evaluate gas exchange, respiratory mechanics, and hemodynamic impact of mechanical ventilation with low tidal volume (VT) in dogs with the use of positive end-expiratory pressure (PEEP) or preceded by alveolar recruitment maneuver (ARM). Study Design: Prospective randomized clinical trial. Animals: Twenty-one healthy client-owned mesocephalic healthy dogs, 1-7 years old, weighing 10-20 kg, and body condition scores 4-6/9 admitted for periodontal treatment. Methods: Isoflurane-anesthetized dogs in dorsal recumbency were ventilated until 1 h with a volume-controlled ventilation mode using 8 mL kg-1 of VT. The dogs were distributed in 2 groups: in the ARM group, PEEP starts in 0 cmH2O, increasing gradually 5 cmH2O every 3 min, until reach 15 cmH2O and decreasing in the same steps until 5 cmH2O, maintaining this value until the end; and PEEP group, in which the pressure 5 cmH2O was instituted from the beginning of anesthesia and maintained the same level up to the end of the anesthesia. Cardiopulmonary, metabolic, oxygenation parameters, and respiratory mechanics were recorded after the anesthesia induction (baseline-BL), 15, 45, and 75 min after BL and during the recovery. Results: The ARM increased the static compliance (Cst) (15 min after baseline) when compared with baseline moment (24.9 ± 5.8 mL cmH20-1 vs. 20.7 ± 5.4 mL cmH20-1-p = 0.0364), oxygenation index (PaO2/FIO2) (505.6 ± 59.2 mmHg vs. 461.2 ± 41.0 mmHg-p = 0.0453) and reduced the shunt fraction (3.4 ± 2.4% vs. 5.5 ± 1.6%-p = 0.062). In the PEEP group, no statistical differences were observed concerning the variables evaluated. At the beginning of the evaluation, the driving pressure (DP) before ARM was significantly greater than all other evaluation time points (6.9 ± 1.8 cmH20). Conclusions and Clinical Relevance: The use of 8 mL kg-1 of VT and 5 cmH20 PEEP without ARM maintain adequate oxygenation and mechanical ventilation in dental surgeries for up to 1 h. The use of ARM slightly improved compliance and oxygenation during the maneuver.

Scaling of axial muscle architecture in juvenile Alligator mississippiensis reveals an enhanced performance capacity of accessory breathing mechanisms.

Quantitative functional anatomy of amniote thoracic and abdominal regions is crucial to understanding constraints on and adaptations for facilitating simultaneous breathing and locomotion. Crocodilians have diverse locomotor modes and variable breathing mechanics facilitated by basal and derived (accessory) muscles. However, the inherent flexibility of these systems is not well studied, and the functional specialisation of the crocodilian trunk is yet to be investigated. Increases in body size and trunk stiffness would be expected to cause a disproportionate increase in muscle force demands and therefore constrain the basal costal aspiration mechanism, necessitating changes in respiratory mechanics. Here, we describe the anatomy of the trunk muscles, their properties that determine muscle performance (mass, length and physiological cross-sectional area [PCSA]) and investigate their scaling in juvenile Alligator mississippiensis spanning an order of magnitude in body mass (359 g-5.5 kg). Comparatively, the expiratory muscles (transversus abdominis, rectus abdominis, iliocostalis), which compress the trunk, have greater relative PCSA being specialised for greater force-generating capacity, while the inspiratory muscles (diaphragmaticus, truncocaudalis ischiotruncus, ischiopubis), which create negative internal pressure, have greater relative fascicle lengths, being adapted for greater working range and contraction velocity. Fascicle lengths of the accessory diaphragmaticus scaled with positive allometry in the alligators examined, enhancing contractile capacity, in line with this muscle's ability to modulate both tidal volume and breathing frequency in response to energetic demand during terrestrial locomotion. The iliocostalis, an accessory expiratory muscle, also demonstrated positive allometry in fascicle lengths and mass. All accessory muscles of the infrapubic abdominal wall demonstrated positive allometry in PCSA, which would enhance their force-generating capacity. Conversely, the basal tetrapod expiratory pump (transversus abdominis) scaled isometrically, which may indicate a decreased reliance on this muscle with ontogeny. Collectively, these findings would support existing anecdotal evidence that crocodilians shift their breathing mechanics as they increase in size. Furthermore, the functional specialisation of the diaphragmaticus and compliance of the body wall in the lumbar region against which it works may contribute to low-cost breathing in crocodilians.

Effects of alveolar recruitment maneuver on end-expiratory lung volume during one-lung ventilation.

PURPOSE: To investigate the effects of alveolar recruitment maneuver (ARM) during one-lung ventilation (OLV) on end-expiratory lung volume (EELV) of the dependent lung. METHODS: Patients who were planned to undergo lung resection surgery for lung tumors and needed OLV for at least 1 h were included in the study. After turning the patients into the lateral position under total intravenous anesthesia, OLV was commenced using a double-lumen endobronchial tube. EELV was measured using the nitrogen washout technique at 20 min after OLV started (baseline) and 15, 30, 45, 60 min after ARM was performed on the dependent lung. RESULTS: Among 42 patients who completed the study, EELV increased at 15 min after ARM by 20% or greater compared with baseline in 21 patients (responders). Responders were significantly shorter in height (158 vs. 165 cm, p = 0.01) and had smaller preoperative functional residual capacity (2.99L vs. 3.65L, p = 0.02) than non-responders. Before ARM, responders had significantly higher driving pressure (14.2 vs. 12.4 cmH2O, p = 0.01) and lower respiratory system compliance (23.6 vs. 31.4 ml/cmH2O, p = 0.0002) than non-responders. Driving pressure temporarily dropped after ARM in responders, while no significant change was observed in non-responders. Fourteen out of 21 responders kept EELV 20% or more increased EELV than baseline at 60 min after ARM. CONCLUSION: EELV of the dependent lung was increased by 20% or greater in half of the patients responding to ARM. The increased volume of the dependent lung caused by ARM was maintained for 60 min in two-thirds of the responders.

[Asthma and obesity]. / Asthme et obésité.

Asthma and obesity are both common diseases in western world. According to the data from our asthma clinic 20 % of our patients are obese and this rate increases up to 25 % in severe asthmatics included in the Belgian Severe Asthma national Registry. Alteration of thoracic mechanics contributes to greater symptom burden and poor asthma control in obese asthmatics. In particular the response to inhaled corticoids is attenuated. Weight loss results in a dramatic improvement in asthma control and should be a major goal in the asthma management of these patients.

Asthme et obésité sont deux pathologies courantes dans les pays occidentaux. Selon les données de notre clinique de l'asthme, 20 % des patients asthmatiques sont obèses, mais ce taux monte à 25 % lorsqu'on considère les patients sévères inclus dans le Registre national belge de l'Asthme sévère. L'altération de la mécanique ventilatoire consécutive à l'excès pondéral rend l'asthme plus symptomatique et plus difficilement contrôlable chez le patient obèse. En particulier, il existe une réponse atténuée à la corticothérapie inhalée. La perte pondérale s'accompagne d'une amélioration spectaculaire de la symptomatologie et doit constituer un objectif thérapeutique primordial chez les patients asthmatiques obèses.

Monitorización respiratoria del paciente pediátrico en la Unidad de Cuidados Intensivos / Respiratory monitoring of pediatric patients in the Intensive Care Unit

Resumen: La monitorización respiratoria representa un importante rol en el cuidado del niño con falla respiratoria aguda. Por tanto, su apropiado uso y correcta interpretación (reconociendo qué señales y variables deben ser priorizadas) deberían ayudar a un mejor entendimiento de la fisiopatología de la enfermedad y de los efectos de las intervenciones terapéuticas. Asimismo, la monitorización del paciente ventilado permite, entre otras determinaciones, evaluar diversos parámetros de la mecánica respiratoria, conocer el estado de los diferentes componentes del sistema respiratorio y guiar los ajustes de la terapia ventilatoria. En esta actualización se describe la utilidad de diversas técnicas de monitorización respiratoria (incluyendo métodos convencionales y otros más recientes), se definen conceptos básicos de mecánica ventilatoria, su interpretación y cómo el adecuado análisis de la información puede ocasionar un impacto en el manejo clínico del paciente.

Abstract: Respiratory monitoring plays an important role in the care of children with acute respiratory failure. Therefore, its proper use and correct interpretation (recognizing which signals and variables should be prioritized) should help to a better understanding of the pathophysiology of the disease and the effects of therapeutic interventions. In addition, ventilated patient monitoring, among other determinations, allows to evaluate various parameters of respiratory mechanics, know the status of the different components of the respiratory system and guide the adjustments of ventilatory therapy. In this update, the usefulness of several techniques of respiratory monitoring including conventional respiratory monitoring and more recent methods are described. Moreover, basic concepts of mechanical ventilation, their interpretation and how the appropriate analysis of the information obtained can cause an impact on the clinical management of the patient are defined.

Non-invasive measurement of abnormal ventilatory mechanics in amyotrophic lateral sclerosis.

INTRODUCTION: In this study we investigated non-invasive, effort-independent measurement of ventilatory mechanics in patients with amyotrophic lateral sclerosis (ALS). METHODS: Ventilatory mechanics were measured by optoelectronic plethysmography (OEP) in ALS patients and matched controls. Analysis determined whether OEP measurements correlated with standard clinical measures. RESULTS: ALS patients (N = 18) had lower forced vital capacity percent predicted (55.2 ± 22.0 L) compared with controls (N = 15; 104.7 ± 16.2 L) and higher ventilatory inefficiency (49.2 ± 9.0 vs. 40.0 ± 3.5, respectively; P < 0.001 for both measures). Lower tidal volumes within the diaphragm area correlated with the dyspnea subscore calculated from the ALS Functional Rating Scale-revised (P = 0.031), and paradoxical movement of the ribcage compared with the abdominal compartment was seen in the most severe cases. CONCLUSIONS: Evaluation of ventilatory mechanics in mild to severe ALS reveals dysfunction that is not readily detected by standard testing and ALS functional severity assessment measures. Muscle Nerve 54: 270-276, 2016.

[Respiratory monitoring of pediatric patients in the Intensive Care Unit]. / Monitorización respiratoria del paciente pediátrico en la Unidad de Cuidados Intensivos.

Respiratory monitoring plays an important role in the care of children with acute respiratory failure. Therefore, its proper use and correct interpretation (recognizing which signals and variables should be prioritized) should help to a better understanding of the pathophysiology of the disease and the effects of therapeutic interventions. In addition, ventilated patient monitoring, among other determinations, allows to evaluate various parameters of respiratory mechanics, know the status of the different components of the respiratory system and guide the adjustments of ventilatory therapy. In this update, the usefulness of several techniques of respiratory monitoring including conventional respiratory monitoring and more recent methods are described. Moreover, basic concepts of mechanical ventilation, their interpretation and how the appropriate analysis of the information obtained can cause an impact on the clinical management of the patient are defined.

Delivery of tidal volume from four anaesthesia ventilators during volume-controlled ventilation: a bench study.

BACKGROUND: Tidal volume (V(T)) must be accurately delivered by anaesthesia ventilators in the volume-controlled ventilation mode in order for lung protective ventilation to be effective. However, the impact of fresh gas flow (FGF) and lung mechanics on delivery of V(T) by the newest anaesthesia ventilators has not been reported. METHODS: We measured delivered V(T) (V(TI)) from four anaesthesia ventilators (Aisys™, Flow-i™, Primus™, and Zeus™) on a pneumatic test lung set with three combinations of lung compliance (C, ml cm H2O(-1)) and resistance (R, cm H2O litre(-1) s(-2)): C60R5, C30R5, C60R20. For each CR, three FGF rates (0.5, 3, 10 litre min(-1)) were investigated at three set V(T)s (300, 500, 800 ml) and two values of PEEP (0 and 10 cm H2O). The volume error = [(V(TI) - V(Tset))/V(Tset)] ×100 was computed in body temperature and pressure-saturated conditions and compared using analysis of variance. RESULTS: For each CR and each set V(T), the absolute value of the volume error significantly declined from Aisys™ to Flow-i™, Zeus™, and Primus™. For C60R5, these values were 12.5% for Aisys™, 5% for Flow-i™ and Zeus™, and 0% for Primus™. With an increase in FGF, absolute values of the volume error increased only for Aisys™ and Zeus™. However, in C30R5, the volume error was minimal at mid-FGF for Aisys™. The results were similar at PEEP 10 cm H2O. CONCLUSIONS: Under experimental conditions, the volume error differed significantly between the four new anaesthesia ventilators tested and was influenced by FGF, although this effect may not be clinically relevant.