Effect of an Individualized Lung Protective Ventilation on Lung Strain and Stress in Children Undergoing Laparoscopy: An Observational Cohort Study.

BACKGROUND: Exaggerated lung strain and stress could damage lungs in anesthetized children. The authors hypothesized that the association of capnoperitoneum and lung collapse in anesthetized children increases lung strain-stress. Their primary aim was to describe the impact of capnoperitoneum on lung strain-stress and the effects of an individualized protective ventilation during laparoscopic surgery in children. METHODS: The authors performed an observational cohort study in healthy children aged 3 to 7 yr scheduled for laparoscopic surgery in a community hospital. All received standard protective ventilation with 5 cm H2O of positive end-expiratory pressure (PEEP). Children were evaluated before capnoperitoneum, during capnoperitoneum before and after lung recruitment and optimized PEEP (PEEP adjusted to get end-expiratory transpulmonary pressure of 0), and after capnoperitoneum with optimized PEEP. The presence of lung collapse was evaluated by lung ultrasound, positive Air-Test (oxygen saturation measured by pulse oximetry 96% or less breathing 21% O2 for 5 min), and negative end-expiratory transpulmonary pressure. Lung strain was calculated as tidal volume/end-expiratory lung volume measured by capnodynamics, and lung stress as the end-inspiratory transpulmonary pressure. RESULTS: The authors studied 20 children. Before capnoperitoneum, mean lung strain was 0.20 ± 0.07 (95% CI, 0.17 to 0.23), and stress was 5.68 ± 2.83 (95% CI, 4.44 to 6.92) cm H2O. During capnoperitoneum, 18 patients presented lung collapse and strain (0.29 ± 0.13; 95% CI, 0.23 to 0.35; P < 0.001) and stress (5.92 ± 3.18; 95% CI, 4.53 to 7.31 cm H2O; P = 0.374) increased compared to before capnoperitoneum. During capnoperitoneum and optimized PEEP, children presenting lung collapse were recruited and optimized PEEP was 8.3 ± 2.2 (95% CI, 7.3 to 9.3) cm H2O. Strain returned to values before capnoperitoneum (0.20 ± 0.07; 95% CI, 0.17 to 0.22; P = 0.318), but lung stress increased (7.29 ± 2.67; 95% CI, 6.12 to 8.46 cm H2O; P = 0.020). After capnoperitoneum, strain decreased (0.18 ± 0.04; 95% CI, 0.16 to 0.20; P = 0.090), but stress remained higher (7.25 ± 3.01; 95% CI, 5.92 to 8.57 cm H2O; P = 0.024) compared to before capnoperitoneum. CONCLUSIONS: Capnoperitoneum increased lung strain in healthy children undergoing laparoscopy. Lung recruitment and optimized PEEP during capnoperitoneum decreased lung strain but slightly increased lung stress. This little rise in pulmonary stress was maintained within safe, lung-protective, and clinically acceptable limits.

The permeability of human red blood cell membranes to hydrogen peroxide is independent of aquaporins.

Hydrogen peroxide (H2O2) not only is an oxidant but also is an important signaling molecule in vascular biology, mediating several physiological functions. Red blood cells (RBCs) have been proposed to be the primary sink of H2O2 in the vasculature because they are the main cellular component of blood with a robust antioxidant defense and a high membrane permeability. However, the exact permeability of human RBC to H2O2 is neither known nor is it known if the mechanism of permeation involves the lipid fraction or protein channels. To gain insight into the permeability process, we measured the partition constant of H2O2 between water and octanol or hexadecane using a novel double-partition method. Our results indicated that there is a large thermodynamic barrier to H2O2 permeation. The permeability coefficient of H2O2 through phospholipid membranes containing cholesterol with saturated or unsaturated acyl chains was determined to be 4 × 10-4 and 5 × 10-3 cm s-1, respectively, at 37 °C. The permeability coefficient of human RBC membranes to H2O2 at 37 °C, on the other hand, was 1.6 × 10-3 cm s-1. Different aquaporin-1 and aquaporin-3 inhibitors proved to have no effect on the permeation of H2O2. Moreover, human RBCs devoid of either aquaporin-1 or aquaporin-3 were equally permeable to H2O2 as normal human RBCs. Therefore, these results indicate that H2O2 does not diffuse into RBCs through aquaporins but rather through the lipid fraction or a still unidentified membrane protein.

Perioperative Continuous Noninvasive Cardiac Output Monitoring in Cardiac Surgery Patients by a Novel Capnodynamic Method.

OBJECTIVES: To test the clinical performance of a novel continuous noninvasive cardiac output (CO) monitoring based on expired carbon dioxide kinetics in cardiac surgery patients. DESIGN: A prospective feasibility pragmatic clinical study. SETTING: A single-center, large community hospital. PARTICIPANTS: Thirty-two patients undergoing cardiac surgery were studied during the intraoperative (before cardiopulmonary bypass) and postoperative (in the intensive care unit before extubation) periods. INTERVENTIONS: CO was measured simultaneously by the continuous capnodynamic method and by transpulmonary thermodilution during changes in the patient's hemodynamic and/or respiratory conditions. MEASUREMENTS AND MAIN RESULTS: The current recommended comparative statistics for CO measurement methods were analyzed, including bias, precision, and percentage error obtained from Bland-Altman analysis, and concordance between methods obtained from the four-quadrant plot analysis to evaluate the trending ability. Bias ± limits of agreement and percentage error were -0.6 (-1.9 to +0.8; 95% CI of 3.73-5.25) L/min and 31% (n = 147 measurements) for the intraoperative period, -0.8 (-2.4 to +0.9; 95% CI of 3.03-5.21) L/min and 41% (n = 66) for the postoperative period, and -0.6 (-2.1 to +0.8; 95% CI of 3.74-5.00) L/min and 34% (n = 213) for the pooled data. The trending analysis obtained a concordance of 82% (n = 65) for the intraoperative and 71% (n = 24) for the early postoperative periods. Aggregation of both data sets gave a concordance of 79% (n = 89). CONCLUSIONS: The continuous capnodynamic method was reliable and in good agreement with the reference method, and had an accuracy and trending ability good enough to make it a possible future alternative for hemodynamic monitoring in the studied population of elective adult cardiac surgery patients.

Positive end-expiratory pressure individualization guided by continuous end-expiratory lung volume monitoring during laparoscopic surgery.

To determine whether end-expiratory lung volume measured with volumetric capnography (EELVCO2) can individualize positive end-expiratory pressure (PEEP) setting during laparoscopic surgery. We studied patients undergoing laparoscopic surgery subjected to Fowler (F-group; n = 20) or Trendelenburg (T-group; n = 20) positions. EELVCO2 was measured at 0° supine (baseline), during capnoperitoneum (CP) at 0° supine, during CP with Fowler (head up + 20°) or Trendelenburg (head down - 30°) positions and after CP back to 0° supine. PEEP was adjusted to preserve baseline EELVCO2 during and after CP. Baseline EELVCO2 was statistically similar to predicted FRC in both groups. At supine and CP, EELVCO2 decreased from baseline values in F-group [median and IQR 2079 (768) to 1545 (725) mL; p = 0.0001] and in T-group [2164 (789) to 1870 (940) mL; p = 0.0001]. Change in body position maintained EELVCO2 unchanged in both groups. PEEP adjustments from 5.6 (1.1) to 10.0 (2.5) cmH2O in the F-group (p = 0.0001) and from 5.6 (0.9) to 10.0 (2.6) cmH2O in T-group (p = 0.0001) were necessary to reach baseline EELVCO2 values. EELVCO2 increased close to baseline with PEEP in the F-group [1984 (600) mL; p = 0.073] and in the T-group [2175 (703) mL; p = 0.167]. After capnoperitoneum and back to 0° supine, PEEP needed to maintain EELVCO2 was similar to baseline PEEP in F-group [5.9 (1.8) cmH2O; p = 0.179] but slightly higher in the T-group [6.5 (2.2) cmH2O; p = 0.006]. Those new PEEP values gave EELVCO2 similar to baseline in the F-group [2039 (980) mL; p = 0.370] and in the T-group [2150 (715) mL; p = 0.881]. Breath-by-breath noninvasive EELVCO2 detected changes in lung volume induced by capnoperitoneum and body position and was useful to individualize the level of PEEP during laparoscopy.Trial registry: Clinicaltrials.gov NCT03693352. Protocol started 1st October 2018.

Dynamic relative regional strain visualized by electrical impedance tomography in patients suffering from COVID-19.

Respiratory failure due to SARS-CoV-2 may progress rapidly. During the course of COVID-19, patients develop an increased respiratory drive, which may induce high mechanical strain a known risk factor for Patient Self-Inflicted Lung Injury (P-SILI). We developed a novel Electrical Impedance Tomography-based approach to visualize the Dynamic Relative Regional Strain (DRRS) in SARS-CoV-2 positive patients and compared these findings with measurements in lung healthy volunteers. DRRS was defined as the ratio of tidal impedance changes and end-expiratory lung impedance within each pixel of the lung region. DRRS values of the ten patients were considerably higher than those of the ten healthy volunteers. On repeated examination, patterns, magnitude and frequency distribution of DRRS were reproducible and in line with the clinical course of the patients. Lung ultrasound scores correlated with the number of pixels showing DRRS values above the derived threshold. Using Electrical Impedance Tomography we were able to generate, for the first time, images of DRRS which might indicate P-SILI in patients suffering from COVID-19.Trial Registration This observational study was registered 06.04.2020 in German Clinical Trials Register (DRKS00021276).

Prevention of atelectasis by continuous positive airway pressure in anaesthetised children: A randomised controlled study.

BACKGROUND: Continuous positive airway pressure (CPAP) prevents peri-operative atelectasis in adults, but its effect in children has not been quantified. OBJECTIVE: The aim of this study was to evaluate the role of CPAP in preventing postinduction and postoperative atelectasis in children under general anaesthesia. DESIGN: A randomised controlled study. SETTING: Single-institution study, community hospital, Mar del Plata. Argentina. PATIENTS: We studied 42 children, aged 6 months to 7 years, American Society of Anesthesiologists physical status class I, under standardised general anaesthesia. INTERVENTIONS: Patients were randomised into two groups: Control group (n = 21): induction and emergence of anaesthesia without CPAP; and CPAP group (n = 21): 5 cmH2O of CPAP during induction and emergence of anaesthesia. Lung ultrasound (LUS) imaging was performed before and 5 min after anaesthesia induction. Children without atelectasis were ventilated in the same manner as the Control group with standard ventilatory settings including 5 cmH2O of PEEP. Children with atelectasis received a recruitment manoeuvre followed by standard ventilation with 8 cmH2O of PEEP. Then, at the end of surgery, LUS images were repeated before tracheal extubation and 60 min after awakening. MAIN OUTCOME MEASURES: Lung aeration score and atelectasis assessed by LUS. RESULTS: Before anaesthesia, all children were free of atelectasis. After induction, 95% in the Control group developed atelectasis compared with 52% of patients in the CPAP group (P < 0.0001). LUS aeration scores were higher (impaired aeration) in the Control group than the CPAP group (8.8 ±â€Š3.8 vs. 3.5 ±â€Š3.3 points; P < 0.0001). At the end of surgery, before tracheal extubation, atelectasis was observed in 100% of children in the Control and 29% of the CPAP group (P < 0.0001) with a corresponding aeration score of 9.6 ±â€Š3.2 and 1.8 ±â€Š2.3, respectively (P < 0.0001). After surgery, 30% of children in the Control group and 10% in the CPAP group presented with residual atelectasis (P < 0.0001) also corresponding to a higher aeration score in the Control group (2.5 ±â€Š3.1) when compared with the CPAP group (0.5 ±â€Š1.5; P < 0.01). CONCLUSION: The use of 5 cmH2O of CPAP in healthy children of the studied age span during induction and emergence of anaesthesia effectively prevents atelectasis, with benefits maintained during the first postoperative hour. TRIAL REGISTRY: Clinicaltrials.gov NCT03461770.

Multimodal non-invasive monitoring to apply an open lung approach strategy in morbidly obese patients during bariatric surgery.

To evaluate the use of non-invasive variables for monitoring an open-lung approach (OLA) strategy in bariatric surgery. Twelve morbidly obese patients undergoing bariatric surgery received a baseline protective ventilation with 8 cmH2O of positive-end expiratory pressure (PEEP). Then, the OLA strategy was applied consisting in lung recruitment followed by a decremental PEEP trial, from 20 to 8 cmH2O, in steps of 2 cmH2O to find the lung's closing pressure. Baseline ventilation was then resumed setting open lung PEEP (OL-PEEP) at 2 cmH2O above this pressure. The multimodal non-invasive variables used for monitoring OLA consisted in pulse oximetry (SpO2), respiratory compliance (Crs), end-expiratory lung volume measured by a capnodynamic method (EELVCO2), and esophageal manometry. OL-PEEP was detected at 15.9 ± 1.7 cmH2O corresponding to a positive end-expiratory transpulmonary pressure (PL,ee) of 0.9 ± 1.1 cmH2O. ROC analysis showed that SpO2 was more accurate (AUC 0.92, IC95% 0.87-0.97) than Crs (AUC 0.76, IC95% 0.87-0.97) and EELVCO2 (AUC 0.73, IC95% 0.64-0.82) to detect the lung's closing pressure according to the change of PL,ee from positive to negative values. Compared to baseline ventilation with 8 cmH2O of PEEP, OLA increased EELVCO2 (1309 ± 517 vs. 2177 ± 679 mL) and decreased driving pressure (18.3 ± 2.2 vs. 10.1 ± 1.7 cmH2O), estimated shunt (17.7 ± 3.4 vs. 4.2 ± 1.4%), lung strain (0.39 ± 0.07 vs. 0.22 ± 0.06) and lung elastance (28.4 ± 5.8 vs. 15.3 ± 4.3 cmH2O/L), respectively; all p < 0.0001. The OLA strategy can be monitored using noninvasive variables during bariatric surgery. This strategy decreased lung strain, elastance and driving pressure compared with standard protective ventilatory settings.Clinical trial number NTC03694665.

Photoplethysmographic characterization of vascular tone mediated changes in arterial pressure: an observational study.

To determine whether a classification based on the contour of the photoplethysmography signal (PPGc) can detect changes in systolic arterial blood pressure (SAP) and vascular tone. Episodes of normotension (SAP 90-140 mmHg), hypertension (SAP > 140 mmHg) and hypotension (SAP < 90 mmHg) were analyzed in 15 cardiac surgery patients. SAP and two surrogates of the vascular tone, systemic vascular resistance (SVR) and vascular compliance (Cvasc = stroke volume/pulse pressure) were compared with PPGc. Changes in PPG amplitude (foot-to-peak distance) and dicrotic notch position were used to define 6 classes taking class III as a normal vascular tone with a notch placed between 20 and 50% of the PPG amplitude. Class I-to-II represented vasoconstriction with notch placed > 50% in a small PPG, while class IV-to-VI described vasodilation with a notch placed < 20% in a tall PPG wave. 190 datasets were analyzed including 61 episodes of hypertension [SAP = 159 (151-170) mmHg (median 1st-3rd quartiles)], 84 of normotension, SAP = 124 (113-131) mmHg and 45 of hypotension SAP = 85(80-87) mmHg. SAP were well correlated with SVR (r = 0.78, p < 0.0001) and Cvasc (r = 0.84, p < 0.0001). The PPG-based classification correlated well with SAP (r = - 0.90, p < 0.0001), SVR (r = - 0.72, p < 0.0001) and Cvasc (r = 0.82, p < 0.0001). The PPGc misclassified 7 out of the 190 episodes, presenting good accuracy (98.4% and 97.8%), sensitivity (100% and 94.9%) and specificity (97.9% and 99.2%) for detecting episodes of hypotension and hypertension, respectively. Changes in arterial pressure and vascular tone were closely related to the proposed classification based on PPG waveform.Clinical Trial Registration NTC02854852.

Lung recruitment prevents collapse during laparoscopy in children: A randomised controlled trial.

BACKGROUND: Capnoperitoneum and anaesthesia impair lung aeration during laparoscopy in children. These changes can be detected and monitored at the bedside by lung ultrasound (LUS). OBJECTIVE: The aim of our study was to assess the impact of general anaesthesia and capnoperitoneum on lung collapse and the potential preventive effect of lung recruitment manoeuvres, using LUS in children undergoing laparoscopy. DESIGN: Randomised controlled study. SETTING: Single-institution study, community hospital, Mar del Plata, Argentina. PATIENTS: Forty-two children American Society of Anesthesiologists I-II aged 6 months to 7 years undergoing laparoscopy. INTERVENTIONS: All patients were studied using LUS before, during and after capnoperitoneum. Children were allocated to a control group (C-group, n=21) receiving standard protective ventilation, or to a lung recruitment manoeuvre group (RM-group) (n=21), in which lung recruitment manoeuvres were performed after recording baseline LUS images before capnoperitoneum. Loss of aeration was scored by summing a progressive grading from 0 to 3 assigned to each of 12 lung areas, based on the detection of four main ultrasound patterns: normal aeration = 0, partial loss-mild = 1, partial loss-severe = 2, total loss-consolidation = 3. MAIN OUTCOME MEASURES: Lung aeration score and atelectasis assessed by ultrasound. RESULTS: Before capnoperitoneum and recruitment manoeuvres in the treated group the two groups presented similar ultrasound scores (5.95 ±â€Š4.13 vs. 5.19 ±â€Š3.33, P = 0.5). In the RM-group, lung aeration significantly improved both during (2.71 ±â€Š2.47) and after capnoperitoneum (2.52 ±â€Š2.86), compared with the C-group (6.71 ±â€Š3.54, P < 0.001, and 8.48 ±â€Š3.22, P < 0.001, respectively). There was no statistically significant difference in the percentage of atelectasis before capnoperitoneum and recruitment manoeuvres in the RM-group (62%) and in the C-group (47%, P = 0.750). However, during capnoperitoneum, only 19% of the RM-group had atelectasis compared with 80% in the C-group (P < 0.001). CONCLUSION: The majority of children undergoing laparoscopy have anaesthesia-induced atelectasis. In most cases, lung collapse due to capnoperitoneum could have been prevented by recruitment manoeuvres followed by positive-end expiratory pressure. TRIAL REGISTRY NUMBER: NCT02824146.

Lung recruitment improves right ventricular performance after cardiopulmonary bypass: A randomised controlled trial.

BACKGROUND: Atelectasis after cardiopulmonary bypass (CPB) can affect right ventricular (RV) performance by increasing its outflow impedance. OBJECTIVE: The aim of this study was to determine whether a lung recruitment manoeuvre improves RV function by re-aerating the lung after CPB. DESIGN: Randomised controlled study. SETTING: Single-institution study, community hospital, Córdoba, Argentina. PATIENTS: Forty anaesthetised patients with New York Heart Association class I or II, preoperative left ventricular ejection fraction at least 50% and Euroscore 6 or less scheduled for cardiac surgery with CPB. INTERVENTIONS: Patients were assigned to receive either standard ventilation with 6 cmH2O of positive end-expiratory pressure (PEEP; group C, n = 20) or standard ventilation with a recruitment manoeuvre and 10 cmH2O of PEEP after surgery (group RM, n = 20). RV function, left ventricular cardiac index (CI) and lung aeration were assessed by transoesophageal echocardiography (TOE) before, at the end of surgery and 30 min after surgery. MAIN OUTCOME MEASURES: RV function parameters and atelectasis assessed by TOE. RESULTS: Haemodynamic data and atelectasis were similar between groups before surgery. At the end of surgery, CI had decreased from 2.9 ±â€Š1.1 to 2.6 ±â€Š0.9 l min m in group C (P = 0.24) and from 2.8 ±â€Š1.0 to 2.6 ±â€Š0.8 l min m in group RM (P = 0.32). TOE-derived RV function parameters confirmed a mild decrease in RV performance in 95% of patients, without significant differences between groups (multivariate Hotelling t-test P = 0.16). Atelectasis was present in 18 patients in group C and 19 patients in group RM (P = 0.88). After surgery, CI decreased further from 2.6 to 2.4 l min m in group C (P = 0.17) but increased from 2.6 to 3.7 l min m in group RM (P < 0.001). TOE-derived RV function parameters improved only in group RM (Hotelling t-test P < 0.001). Atelectasis was present in 100% of patients in group C but only in 10% of those in group RM (P < 0.001). CONCLUSION: Atelectasis after CPB impairs RV function but this can be resolved by lung recruitment using 10 cmH2O of PEEP. TRIAL REGISTRATION: Protocol started on October 2014.

Accuracy of transthoracic lung ultrasound for diagnosing anesthesia-induced atelectasis in children.

BACKGROUND: The aim of this study was to test the accuracy of lung sonography (LUS) to diagnose anesthesia-induced atelectasis in children undergoing magnetic resonance imaging (MRI). METHODS: Fifteen children with American Society of Anesthesiology's physical status classification I and aged 1 to 7 yr old were studied. Sevoflurane anesthesia was performed with the patients breathing spontaneously during the study period. After taking the reference lung MRI images, LUS was carried out using a linear probe of 6 to 12 MHz. Atelectasis was documented in MRI and LUS segmenting the chest into 12 similar anatomical regions. Images were analyzed by four blinded radiologists, two for LUS and two for MRI. The level of agreement for the diagnosis of atelectasis among observers was tested using the κ reliability index. RESULTS: Fourteen patients developed atelectasis mainly in the most dependent parts of the lungs. LUS showed 88% of sensitivity (95% CI, 74 to 96%), 89% of specificity (95% CI, 83 to 94%), and 88% of accuracy (95% CI, 83 to 92%) for the diagnosis of atelectasis taking MRI as reference. The agreement between the two radiologists for diagnosing atelectasis by MRI was very good (κ, 0.87; 95% CI, 0.72 to 1; P < 0.0001) as was the agreement between the two radiologists for detecting atelectasis by LUS (κ, 0.90; 95% CI, 0.75 to 1; P < 0.0001). MRI and LUS also showed good agreement when data from the four radiologists were pooled and examined together (κ, 0.75; 95% CI, 0.69 to 0.81; P < 0.0001). CONCLUSION: LUS is an accurate, safe, and simple bedside method for diagnosing anesthesia-induced atelectasis in children.

Clinical validation of the Air-Test for the non-invasive detection of perioperative atelectasis in children.

BACKGROUND: The incidence of anesthesia-induced atelectasis in children is high and closely related to episodes of hypoxemia. The Air-Test is a simple maneuver to detect lung collapse. By a step-reduction in FiO2 to 0.21, a fall in pulse-oximetry hemoglobin saturation <97% unmasks the presence of collapse-related shunt in healthy lungs. The aim of this study was to validate the Air-Test as a diagnostic tool to detect perioperative atelectasis in children using lung ultrasound as a reference. METHODS: We first assessed the Air-Test in a retrospective cohort of 88 anesthetized children (Retrospective study) followed by a prospective study performed in 72 children (45 postconceptional weeks to 16 years old) using a similar protocol (Validation study). We analyzed the performance of the Air-Test to detect atelectasis by an operating characteristic curve (ROC) analysis, using lung ultrasound consolidation score as reference. RESULTS: Preoperative SpO2 was normal in both studies (retrospective 98.7±0.6%, validation 99.0±0.9%). The Air-Test, with a SpO2 cut point <97%, resulted positive in 67 patients in the retrospective study (SpO2 93.3±2.1%) and in 59 in the validation study (SpO2 94.9±1.8%); both P<0.0001. In the validation study, the Air-Test showed a sensitivity of 0.91 (95% CI 0.85-0.92), specificity of 1.00 (95% CI 0.84-1) and an area under the curve (AUC) of 0.98 (95% CI 0.97-1.00). AUC between both studies was similar (P=0.16). CONCLUSIONS: The Air-Test is a noninvasive and accurate method to detect atelectasis in healthy anesthetized children. It can be used as a screening tool to individualize patients that can benefit from lung recruitment maneuvers.

Alveolar capillary dysplasia with misalignment of pulmonary veins in a premature newborn: the role of lung ultrasound.

BACKGROUND: Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a lethal neonatal lung disorder characterized by the decrease of the alveolar units, abnormalities in the air-blood barrier of the lung, and impaired gas exchange. Typically, it affects a full-term newborn; the symptoms usually start within a few hours after birth, resulting in severe respiratory distress and pulmonary hypertension. In most of the cases, this disorder is refractory to conventional pulmonary support. CASE PRESENTATION: We report a case of a newborn male of 29 weeks gestational age, with birth weight of 850 g and intrauterine growth restriction. Severe respiratory distress appeared a few minutes after birth; non-invasive ventilatory support was provided in the delivery room and, as a consequence of persistent respiratory failure, he was admitted to the neonatal intensive care unit (NICU) where mechanical ventilation was required. Due to the symptoms and pulmonary ultrasound pattern suggestive of respiratory distress syndrome, surfactant treatment was administered. Lung ultrasound (LU) was used for monitoring the responsiveness to surfactant; severe pulmonary hypertension ensued, followed by respiratory failure, refractory shock, and death within 48 h. Owing to the poor response to the established therapy, ACD/MPV was suspected. The diagnosis was confirmed through autopsy. The main goal of this case report is to show the role of LU for monitoring the evolution of this disorder. CONCLUSION: LU could provide essential information to help diagnose and follow-up the underlying cause of persistent pulmonary hypertension of the newborn in an earlier and more effective way than chest X-ray. LU is suitable for routine monitoring of lung disease in the NICU.

Basic notions of lung ultrasound in neonatology. / Principios básicos de ecografía pulmonar en neonatología.

Lung ultrasound (LU) has gained ground in the diagnosis of most respiratory conditions present since birth. It is highly sensitive to variations in air content and pulmonary fluids and functions as a true densitometer of the lung parenchyma with a sensitivity superior to that of radiological studies. A LU is a non-invasive, fast and easy tool that can be used at the patient's bedside and, unlike conventional radiology, does not pose risks of radiation. In addition, a LU provides real-time dynamic information in a variety of neonatal settings and, like heart and brain examinations, can be performed by the neonatologist. The objective of this article is to describe the main artifacts and images that can be found in the neonatal LU, as well as the different aeration patterns, and to highlight their usefulness in the study of the most frequent respiratory disorders of neonates.

La ecografía pulmonar (EP) ha ganado terreno en el diagnóstico de la mayoría de las patologías respiratorias presentes desde el nacimiento. Es altamente sensible a las variaciones del contenido de aire y fluidos pulmonares, y constituye un verdadero densitómetro del parénquima pulmonar con una sensibilidad superior a la de los estudios radiológicos. Es no invasiva, rápida, fácil de realizar junto a la cama del paciente y, a diferencia de la radiología convencional, no presenta riesgos de radiación. Además, nos proporciona información dinámica en tiempo real en una variedad de entornos neonatales y, al igual que las evaluaciones del corazón y el cerebro, puede ser realizada por el neonatólogo. El objetivo de esta publicación es mostrar los principales artefactos e imágenes que se pueden encontrar en la EP neonatal, así como los diferentes patrones de aireación, y destacar su utilidad en el estudio de los trastornos respiratorios más frecuentes del neonato.

Short communication: ultrasound-guided percutaneous cryoanalgesia of intercostal nerves for uniportal video-assisted thoracic surgery.

BACKGROUND: Pain after thoracic surgery impairs lung function and increases the rate of postoperative pulmonary complications. Ultrasound-guided percutaneous cryoanalgesia of intercostal nerves constitutes a valid option for adequate postoperative analgesia. A key issue for a successful cryoanalgesia is placing the cryoprobe tip close to the intercostal nerve. This report describes an ultrasound technique using a high-resolution ultrasound probe to accomplish this goal. FINDINGS: Images of five anesthetized patients undergoing uniportal video-thoracoscopic surgeries are used as clinical examples. In the lateral position, a high-frequency 12 MHz probe is placed longitudinally at 5-7 cm parallel to the spine at the 4th, 5th, and 6th ipsilateral intercostal spaces. Ultrasound images detect the intercostal neurovascular bundle and a 14G angiocath is placed beside the nerve. The cryoprobe is inserted throughout the 14G catheter and the cryoanalgesia cycle is performed for 3 min. Two ultrasound signs confirm the right cryoprobe position close to the nerve: one is a color Doppler twinkling artifact that is seen as the quick shift of colors that delineates the cryoprobe contour. The other is a spherical hypoechoic image caused by the ice ball formed at the cryoprobe tip. CONCLUSIONS: Ultrasound images obtained with a high-frequency probe allow precise location of the cryoprobe tip close to the intercostal nerve for cold axonotmesis.

Blood cell respiration rates and mtDNA copy number: A promising tool for the diagnosis of mitochondrial disease.

Human mitochondrial diseases are a group of heterogeneous diseases caused by defects in oxidative phosphorylation, due to mutations in mitochondrial (mtDNA) or nuclear DNA. The diagnosis of mitochondrial disease is challenging since mutations in multiple genes can affect mitochondrial function, there is considerable clinical variability and a poor correlation between genotype and phenotype. Herein we assessed mitochondrial function in peripheral blood mononuclear cells (PBMCs) and platelets from volunteers without known metabolic pathology and patients with mitochondrial disease. Oxygen consumption rates were evaluated and respiratory parameters indicative of mitochondrial function were obtained. A negative correlation between age and respiratory parameters of PBMCs from control individuals was observed. Surprisingly, respiratory parameters of PBMCs normalized by cell number were similar in patients and young controls. Considering possible compensatory mechanisms, mtDNA copy number in PBMCs was quantified and an increase was found in patients with respect to controls. Hence, respiratory parameters normalized by mtDNA copy number were determined, and in these conditions a decrease in maximum respiration rate and spare respiratory capacity was observed in patients relative to control individuals. In platelets no decay was seen in mitochondrial function with age, while a reduction in basal, ATP-independent and ATP-dependent respiration normalized by cell number was detected in patients compared to control subjects. In summary, our results offer promising perspectives regarding the assessment of mitochondrial function in blood cells for the diagnosis of mitochondrial disease, minimizing the need for invasive procedures such as muscle biopsies, and for following disease progression and response to treatments.

Feasibility of postural lung recruitment maneuver in children: a randomized, controlled study.

BACKGROUND: Pulmonary atelectasis in anesthetized children is easily reverted by lung recruitment maneuvers. However, the high airways pressure reached during the maneuver could negatively affect hemodynamics. The aim of this study is to assess the effect and feasibility of a postural lung recruitment maneuver (P-RM); i.e., a new maneuver that opens up the atelectatic lung areas based on changing the child's body position under constant ventilation with moderated driving pressure (12 cmH2O) and of positive end-expiratory pressure (PEEP, 10 cmH2O). Forty ASA I-II children, aged 6 months to 7 years, subjected to general anesthesia were studied. Patients were ventilated with volume control mode using standard settings with 5 cmH2O of PEEP. They were randomized into two groups: (1) control group (C group, n = 20)-ventilation was turned to pressure control ventilation using a fixed driving pressure of 12 cmH2O. PEEP was increased from 5 to 10 cmH2O during 3 min maintaining the supine position. (2) P-RM group (n = 20)-patients received the same increase in driving pressure and PEEP, but they were placed, respectively, in the left lateral position, in the right lateral position (90 s each), and back again into the supine position after 3 min. Then, ventilation returned to baseline settings in volume control mode. Lung ultrasound-derived aeration score and respiratory compliance were assessed before (T1) and after (T2) 10 cmH2O of PEEP was applied. RESULTS: At baseline ventilation (T1), both groups showed similar aeration score (P-RM group 9.9 ± 1.9 vs C group 10.4 ± 1.9; p = 0.463) and respiratory compliance (P-RM group 15 ± 6 vs C group 14 ± 6 mL/cmH2O; p = 0.517). At T2, the aeration score decreased in the P-RM group (1.5 ± 1.6 vs 9.9 ± 2.1; p < 0.001), but remained without changes in the C group (9.9 ± 2.1; p = 0.221). Compliance was higher in the P-RM group (18 ± 6 mL/cmH2O) when compared with the C group (14 ± 5 mL/cmH2O; p = 0.001). CONCLUSION: Lung aeration and compliance improved only in the group in which a posture change strategy was applied.

Postural lung recruitment assessed by lung ultrasound in mechanically ventilated children.

BACKGROUND: Atelectasis is a common finding in mechanically ventilated children with healthy lungs. This lung collapse cannot be overcome using standard levels of positive end-expiratory pressure (PEEP) and thus for only individualized lung recruitment maneuvers lead to satisfactory therapeutic results. In this short communication, we demonstrate by lung ultrasound images (LUS) the effect of a postural recruitment maneuver (P-RM, i.e., a ventilatory strategy aimed at reaerating atelectasis by changing body position under constant ventilation). RESULTS: Data was collected in the operating room of the Hospital Privado de Comunidad, Mar del Plata, Argentina. Three anesthetized children undergoing mechanical ventilation at constant settings were sequentially subjected to the following two maneuvers: (1) PEEP trial in the supine position PEEP was increased to 10 cmH2O for 3 min and then decreased to back to baseline. (2) P-RM patient position was changed from supine to the left and then to the right lateral position for 90 s each before returning to supine. The total P-RM procedure took approximately 3 min. LUS in the supine position showed similar atelectasis before and after the PEEP trial. Contrarily, atelectasis disappeared in the non-dependent lung when patients were placed in the lateral positions. Both lungs remained atelectasis free even after returning to the supine position. CONCLUSIONS: We provide LUS images that illustrate the concept and effects of postural recruitment in children. This maneuver has the advantage of achieving recruitment effects without the need to elevate airways pressures.