Atelectasis in children undergoing either propofol infusion or positive pressure ventilation anesthesia for magnetic resonance imaging

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.

Comparison of the effect of two recruitment manoeuvres to conventional ventilation on lung atelectasis in paediatric laparoscopic surgery- a prospective randomised controlled trial

BACKGROUND

There is a high incidence of pulmonary atelectasis during paediatric laparoscopic surgeries. The authors hypothesised that utilising a recruitment manoeuvre or using continuous positive airway pressure may prevent atelectasis compared to conventional ventilation.

OBJECTIVE

The primary objective was to compare the degree of lung atelectasis diagnosed by lung ultrasound (LUS) using three different ventilation techniques in children undergoing laparoscopic surgeries.

DESIGN

Randomised, prospective three-arm trial.

SETTING

Single institute, tertiary care, teaching hospital.

PATIENTS

Children of ASA PS 1 and 2 up to the age of 10 years undergoing laparoscopic surgery with pneumoperitoneum lasting for more than 30 min.

INTERVENTION

Random allocation to one of the three study groups: CG group: Inspiratory pressure adjusted to achieve a TV of 5-8 ml/kg, PEEP of 5 cm H2O, respiratory rate adjusted to maintain end-tidal carbon dioxide (ETCO2) between 30-40 mm Hg with manual ventilation and no PEEP at induction. RM group: A recruitment manoeuvre of providing a constant pressure of 30 cm H2O for ten seconds following intubation was applied. A PEEP of 10 cm H2O was maintained intraoperatively. CPAP group: Intraoperative maintenance with PEEP 10 cm H2O with CPAP of 10 cm H2O at induction using mechanical ventilation was done.

OUTCOME MEASURES

Lung atelectasis score at closure assessed by LUS.

RESULTS

Post induction, LUS was comparable in all three groups. At the time of closure, the LUS for the RM group (8.6 ± 4.9) and the CPAP group (8.8 ± 6.8) were significantly lower (p < 0.05) than the CG group (13.3 ± 3.8). In CG and CPAP groups, the score at closure was significantly higher than post-induction. The PaO2/FiO2 ratio was significantly higher (p < 0.05) for the RM group (437.1 ± 44.9) and CPAP group (421.6 ± 57.5) than the CG group (361.3 ± 59.4) at the time of pneumoperitoneum.

CONCLUSION

Application of a recruitment manoeuvre post-intubation or CPAP during induction and maintenance with a high PEEP leads to less atelectasis than conventional ventilation during laparoscopic surgery in paediatric patients.

TRIAL REGISTRY

CTRI/2019/08/02058.

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.

EDITOR’S PERSPECTIVE

Effect of ultrasound-guided transversus abdominis plane block in reducing atelectasis after laparoscopic surgery in children: A randomized clinical trial

Background

Atelectasis is a commonly observed postoperative complication of general anesthesia in children. Pulmonary protective ventilation strategies have been reported to have a beneficial effect on postoperative atelectasis in children. Therefore, the present study aimed to evaluate the efficacy of the ultrasound-guided transversus abdominis plane (TAP) block technique in preventing the incidence of postoperative atelectasis in children.

Materials and methods

This study enrolled 100 consecutive children undergoing elective laparoscopic bilateral hernia repair and randomly divided them into the control and TAP groups. Conventional lung-protective ventilation was initiated in both groups after the induction of general anesthesia. The children in the TAP group received an ultrasound-guided TAP block with 0.3 mL/kg of 0.5% ropivacaine after the induction of anesthesia.

Results

Anesthesia-induced atelectasis was observed in 24% and 84% of patients in the TAP (n = 50) and control (n = 50) groups, respectively, before discharge from the post-anesthetic care unit (T3; PACU) (odds ratio [OR], 0.062; 95% confidence interval [CI], 0.019-0.179; P < 0.001). No significant difference was observed between the control and TAP groups in terms of the lung ultrasonography (LUS) scores 5 min after endotracheal intubation (T1). However, the LUS scores were lower in the TAP group than those in the control group at the end of surgery (T2, P < 0.01) and before discharge from the PACU (T3, P < 0.001). Moreover, the ace, legs, activity, cry and consolability (FLACC) pain scores in the TAP group were lower than those in the control group at each postoperative time point.

Conclusion

Ultrasound-guided TAP block effectively reduced the incidence of postoperative atelectasis and alleviated pain in children undergoing laparoscopic surgery.

Lung ultrasound-guided best positive end-expiratory pressure in neonatal anesthesia: a proposed randomized, controlled study

BACKGROUND

Atelectasis is a common complication in neonatal anesthesia. Lung ultrasound (LUS) can be used intraoperatively to evaluate and recognize atelectatic lung areas. Hypotheses for the study are: (1) The use of LUS to guide choice of best positive end-expiratory pressure (PEEP) can lead to reduction of FiO2 to achieve same saturations of oxygen (SpO2). (2) In a less de-recruited lung, there will be less postoperative pulmonary complications. (3) Static respiratory system compliance could be different. (4) Hemodynamic parameters and amount of fluids infused or need for vasopressors intraoperatively could be different.

METHODS

We propose a randomized controlled trial that compares standard PEEP settings with LUS-guided PEEP choice in patients under 2 months of age undergoing general anesthesia.

RESULTS

The primary aim is to determine whether LUS-guided PEEP choice in neonatal anesthesia, compared to standard PEEP choice, can lead to reduction of FiO2 applied to the ventilatory setting in order to maintain same SpO2s. Secondary aims are to determine whether patients treated with LUS-guided PEEP will develop less postoperative pulmonary complications, will have a significant difference in hemodynamic parameters and amount of fluids or vasopressors infused, and in static respiratory system compliance.

CONCLUSIONS

We expect a significant reduction of FiO2 in LUS-guided ventilation.

IMPACT

Lung atelectasis is extremely common in neonatal anesthesia, because of the physiology of the neonatal lung and chest wall and leads to hypoxemia, being a lung area with a perfusion/ventilation mismatch. Raising inspired fraction of oxygen can overcome temporarily hypoxemia but oxygen is a toxic compound for newborns. Lung ultrasound (LUS) can detect atelectasis at bedside and be used to optimize ventilator settings including choice of positive end-expiratory pressure (PEEP). This randomized controlled trial (RCT) aims at demonstrating that LUS-guided choice of best PEEP during neonatal anesthesia can lead to reduction of inspired fractions of oxygen to keep same peripheral saturations SpO2.

Effects of laryngeal mask ventilation on postoperative atelectasis in children undergoing day surgery: a randomized controlled trial

BACKGROUND

To compare the effects of laryngeal mask mechanical ventilation and preserved spontaneous breathing on postoperative atelectasis in children undergoing day surgery.

METHODS

Children aged 3-7 who underwent elective day surgery were randomly divided into a spontaneous breathing group (n = 23) and a mechanical ventilation group (n = 23). All children enrolled in this trial used the same anesthesia induction protocol, the incidence and severity of atelectasis before induction and after operation were collected. In addition, the baseline data, intraoperative vital signs, ventilator parameters and whether there were complications such as reflux and aspiration were also collected. SPSS was used to calculate whether there was a statistical difference between these indicators.

RESULTS

The incidence of atelectasis in the spontaneous breathing group was 91.30%, and 39.13% in the mechanical ventilation group, and the difference was statistically significant (P = 0.001). There was a statistically significant difference in carbon dioxide (P < 0.05), and the severity of postoperative atelectasis in the mechanical ventilation group was lower than that in the spontaneous breathing group (P < 0.05). In addition, there were no significant differences in the vital signs and baseline data of the patients (P > 0.05).

CONCLUSION

Laryngeal mask mechanical ventilation can reduce the incidence and severity of postoperative atelectasis in children undergoing day surgery, and we didn't encounter any complications such as reflux and aspiration in children during the perioperative period, so mechanical ventilation was recommended to be used for airway management.

TRIAL REGISTRATION

The clinical trial was registered retrospectively at the Chinese Clinical Trial Registry. ( https://www.chictr.org.cn . Registration number ChiCTR2300071396, Weiwei Cai, 15 May 2023).

Effect of ultrasound-guided lung recruitment manoeuvre on perioperative atelectasis during laparoscopy in young infants: A randomised controlled trial

BACKGROUND

Pneumoperitoneum is a risk factor for perioperative atelectasis in infants. This research aimed to investigate whether lung recruitment manoeuvres guided by ultrasound are more effective for young infants (<3 months) during laparoscopy under general anaesthesia.

METHODS

Young infants (<3 months) undergoing general anaesthesia during laparoscopic surgery (>2 h) were randomised to either conventional lung recruitment (control group) or ultrasound-guided lung recruitment (ultrasound group) once per hour. Mechanical ventilation was started with a tidal volume of 8 mL·kg-1, positive end-expiratory pressure of 6 cm H2O and 40% inspired oxygen fraction. Lung ultrasound (LUS) was performed four times (T1 was performed 5 min after intubation and before pneumoperitoneum set, T2 was performed after pneumoperitoneum, T3 was performed 1 min after surgery, and T4 was performed before being discharged from post-anaesthesia care unit [PACU]) in each infant. The primary outcome was the incidence of significant atelectasis at T3 and T4 (defined by LUS consolidation score ≥ 2 in any region).

RESULTS

62 babies were enrolled in the experiment and 60 infants were included in the analysis. Before the recruitment, atelectasis was similar between infants randomised to the control or ultrasound group at T1 (83.3% vs 80.0%; P = 0.500) and T2 (83,3% vs 76.7%; P = 0.519). The incidence of atelectasis at T3 and T4 were lower in the ultrasound group (26.7% and 33.3%), compared with infants randomised to conventional lung recruitment (66.7% and 70%) (P = 0.002; P = 0.004; respectively).

CONCLUSIONS

Ultrasound-guided alveolar recruitment reduced the perioperative incidence of atelectasis in infants <3 months during laparoscopy under general anaesthesia.

TRACK-CF prospective cohort study: Understanding early cystic fibrosis lung disease

Background

Lung disease as major cause for morbidity in patients with cystic fibrosis (CF) starts early in life. Its large phenotypic heterogeneity is partially explained by the genotype but other contributing factors are not well delineated. The close relationship between mucus, inflammation and infection, drives morpho-functional alterations already early in pediatric CF disease, The TRACK-CF cohort has been established to gain insight to disease onset and progression, assessed by lung function testing and imaging to capture morpho-functional changes and to associate these with risk and protective factors, which contribute to the variation of the CF lung disease progression.

Methods and design

TRACK-CF is a prospective, longitudinal, observational cohort study following patients with CF from newborn screening or clinical diagnosis throughout childhood. The study protocol includes monthly telephone interviews, quarterly visits with microbiological sampling and multiple-breath washout and as well as a yearly chest magnetic resonance imaging. A parallel biobank has been set up to enable the translation from the deeply phenotyped cohort to the validation of relevant biomarkers. The main goal is to determine influencing factors by the combined analysis of clinical information and biomaterials. Primary endpoints are the lung clearance index by multiple breath washout and semi-quantitative magnetic resonance imaging scores. The frequency of pulmonary exacerbations, infection with pro-inflammatory pathogens and anthropometric data are defined as secondary endpoints.

Discussion

This extensive cohort includes children after diagnosis with comprehensive monitoring throughout childhood. The unique composition and the use of validated, sensitive methods with the attached biobank bears the potential to decisively advance the understanding of early CF lung disease.

Ethics and trial registration

The study protocol was approved by the Ethics Committees of the University of Heidelberg (approval S-211/2011) and each participating site and is registered at clinicaltrials.gov (NCT02270476).

The effect of ultrasound-guided lung recruitment maneuvers on atelectasis in lung-healthy patients undergoing laparoscopic gynecologic surgery: a randomized controlled trial

BACKGROUND

Atelectasis is the primary cause of hypoxemia during general anesthesia. This study aimed to evaluate the impact of the combination of recruitment maneuvers (RM) and positive end-expiratory pressure (PEEP) on the incidence of atelectasis in adult women undergoing gynecologic laparoscopic surgery using pulmonary ultrasound.

METHODS

In this study, 42 patients with healthy lungs undergoing laparoscopic gynecologic surgery were randomly divided into the recruitment maneuver group (RM group; 6 cm H₂O PEEP and RM) or the control group (C group; 6 cm H₂O PEEP and no RM), 21 patients in each group. Volume-controlled ventilation was used in all selected patients, with a tidal volume of 6-8 mL·kg^-1 of ideal body weight. When atelectasis was detected, patients in the RM group received ultrasound-guided RM, while those in the C group received no intervention. The incidence and severity of atelectasis were determined using lung ultrasound scores.

RESULTS

A total of 41 patients were investigated. The incidence of atelectasis was lower in the RM group (40%) than in the C group (80%) 15 min after arrival in the post-anesthesia care unit (PACU). Meanwhile, lung ultrasound scores (LUSs) were lower in the RM group compared to the C group. In addition, the differences in the LUS between the two groups were mainly due to the differences in lung ultrasound scores in the posterior regions. However, this difference did not persist after 24 h of surgery.

CONCLUSIONS

In conclusion, the combination of RM and PEEP could reduce the incidence of atelectasis in patients with healthy lungs 15 min after arrival at the PACU; however, it disappeared within 24 h after surgery.

TRIAL REGISTRATION

(Prospectively registered): ChiCTR2000033529 . Registered on 4/6/2020.

Atelectasis and lung recruitment in pediatric anesthesia: An educational review

General anesthesia is associated with development of pulmonary atelectasis. Children are more vulnerable to the development and adverse effects of atelectasis. We review the physiology and risk factors for the development of atelectasis in pediatric patients under general anesthesia. We discuss the clinical significance of atelectasis, the use and value of recruitment maneuvers, and other techniques available to minimize lung collapse. This review demonstrates the value of a recruitment maneuver, maintaining positive end-expiratory pressure (PEEP) until extubation and lowering FiO₂ where possible in the daily practice of the pediatric anesthetist.

Perioperative Pulmonary Atelectasis: Part II. Clinical Implications

The development of pulmonary atelectasis is common in the surgical patient. Pulmonary atelectasis can cause various degrees of gas exchange and respiratory mechanics impairment during and after surgery. In its most serious presentations, lung collapse could contribute to postoperative respiratory insufficiency, pneumonia, and worse overall clinical outcomes. A specific risk assessment is critical to allow clinicians to optimally choose the anesthetic technique, prepare appropriate monitoring, adapt the perioperative plan, and ensure the patient's safety. Bedside diagnosis and management have benefited from recent imaging advancements such as lung ultrasound and electrical impedance tomography, and monitoring such as esophageal manometry. Therapeutic management includes a broad range of interventions aimed at promoting lung recruitment. During general anesthesia, these strategies have consistently demonstrated their effectiveness in improving intraoperative oxygenation and respiratory compliance. Yet these same intraoperative strategies may fail to affect additional postoperative pulmonary outcomes. Specific attention to the postoperative period may be key for such outcome impact of lung expansion. Interventions such as noninvasive positive pressure ventilatory support may be beneficial in specific patients at high risk for pulmonary atelectasis (e.g., obese) or those with clinical presentations consistent with lung collapse (e.g., postoperative hypoxemia after abdominal and cardiothoracic surgeries). Preoperative interventions may open new opportunities to minimize perioperative lung collapse and prevent pulmonary complications. Knowledge of pathophysiologic mechanisms of atelectasis and their consequences in the healthy and diseased lung should provide the basis for current practice and help to stratify and match the intensity of selected interventions to clinical conditions.

Evaluation of atelectasis using electrical impedance tomography during procedural deep sedation for MRI in small children: A prospective observational trial

STUDY OBJECTIVE

To investigate the variation of poorly ventilated lung units (i.e., silent spaces) in children undergoing procedural sedation in a day-hospital setting, until discharge home from the Post-Anesthesia Care Unit (PACU).

DESIGN

Prospective, single-center, observational cohort trial.

SETTING

This study was conducted at the radiology department and in PACU at Bern University Hospital (Switzerland), a tertiary care hospital.

PATIENTS

We included 25 children (1-6 years, ASA I-III) scheduled for cerebral magnetic resonance imaging scan, spontaneously breathing under deep sedation. Children planned for tracheal intubation, supraglottic airway insertion, or with contraindication for propofol were excluded.

INTERVENTION

After intravenous or inhaled induction, deep sedation was performed with 10 mg/kg/h Propofol. All children received nasal oxygen 0.3 ml/kg/min.

MEASUREMENTS

The proportion of silent spaces and the global inhomogeneity index were determined at each of five procedural points, using electrical impedance tomography: before induction (T1); before (T2) and after (T3) magnetic resonance imaging; at the end of sedation before transport to the PACU (T4); and before hospital discharge (T5).

MAIN RESULTS

The median [interquartile range (IQR)] proportion of silent spaces at the five analysis points were: T1, 5% [2%-14%]; T2, 10% [7%-14%]; T3, 12% [5%-23%]; T4, 12% [7%-24%]; and T5, 3% [2%-11%]. These defined significant changes in silent spaces over the course of sedation (p = 0.009), but no differences in silent spaces from before induction to before discharge from the PACU (T1 vs. T5; p = 0.29). Median [IQR] global inhomogeneity indices were 0.57 [0.55-0.58], 0.56 [0.53-0.59], 0.56 [0.54-0.59], 0.57 [0.54-0.60] and 0.56 [0.54-0.57], respectively (p = 0.93). None of the children reported anesthesia-related complications.

CONCLUSION

Deep sedation results in significantly increased poorly ventilated lung units during sedation. However, this does not significantly affect ventilation homogeneity, which was fully resolved at discharge from the PACU.

TRIAL REGISTRATION

clinicaltrials.gov, identifier NCT04507581.

Minimal atelectasis and poorly aerated lung on thoracic CT images of normal dogs acquired under sedation

General anesthesia optimizes image quality of thoracic CT in dogs by providing patient immobilization and respiratory control. However, it also comes with disadvantages that may serve as a detractor to the use of CT in veterinary practice. With the use of multidetector helical CT combined with injectable sedation for restraint, parameters such as atelectasis and poorly aerated lung should not be appreciably different from what has been observed in dogs under general anesthesia. This prospective pilot study aimed to evaluate the mean lung attenuation and the amount of atelectasis and poorly aerated lung on thoracic CT images acquired under injectable sedation in normal dogs. The entire thorax of 10 client-owned dogs was scanned. Attenuation measurements were generated by three-dimensional reconstruction software. Mean ± SD lung attenuation was -707.0 ± 60.0. Atelectasis was not identified on any of the scans. Hypoinflated lung, the percentage of lung parenchyma with attenuation greater than -500 and -250 Hounsfield units (HU), was 10.7 ± 4.7% and 2.4 ± 1.2% (mean ± SD), respectively. There was no significant change in these percentages over time. Compared to previously published data, thoracic CT images obtained under sedation had mean attenuation comparable to normal expiratory lung and a lower percentage of poorly aerated lung compared to that of anesthetized dogs. Using sedation to complete canine thoracic CT does not itself lead to alterations of lung attenuation and may confer less hypoinflation and atelectasis than general anesthesia.

Trends in Pediatric MRI sedation/anesthesia at a tertiary medical center over time

BACKGROUND

Each year, hundreds of thousands of children require sedation/anesthesia to facilitate MRI scans. Anesthetic techniques for accomplishing sedation/anesthesia vary widely between institutions and providers, with unclear implications for patient safety.

AIMS

We sought to establish trends in anesthetic practice for pediatric MRI sedation/anesthesia across a 7-year period and determine rates of adverse events, considering technique used, age, and ASA physical classification status (ASA-PS).

METHODS

Using established data resources, we analyzed 24 052 anesthetics performed by anesthesiologists for MRI scans between 5/1/2013 and 12/31/2019 on patients less than 18 years old, focusing on medications used, trends of use, and associated adverse events. Adverse events (hypoxia, hypotension, bradycardia) were defined by deviation from age norms and accessed via the electronic anesthetic record database. The Cochran-Armitage test was used to assess trends over time in categorical data, and one-way ANOVA was used to analyze continuous data. Multivariable logistic regression analysis was implemented to determine the independent associations between anesthetic technique and adverse events while adjusting for age, ASA-PS, and weight.

RESULTS

The most significant trends noted were a decrease in "propofol-only" anesthetic techniques and an increase in propofol and dexmedetomidine combination techniques. Mild desaturation (80-89% SpO₂ ) occurred in 4.22% of cases with more significant hypoxia much rarer (0.44% of cases having desaturation <70% SpO₂ ). Bradycardia occurred in 2.39% of cases and hypotension in 1.75% of cases. Major adverse events were rare.

CONCLUSIONS

We provide the largest report of the nature of MRI sedation/anesthesia as practiced by anesthesiologists in a large children's hospital. We demonstrate that, even in a large system, anesthetic techniques are pliable and shift significantly over time. Our data also support a high level of safety within our system, despite a case mix likely higher in risk than those in most of the previously published studies.

Factors Associated with Occurrence of Atelectasis during Sedation for Imaging in Pediatric Patients: A Retrospective Single Center Cohort Study

Sedation can induce atelectasis which may cause suboptimal image quality. This study aimed to identify factors associated with the occurrence of atelectasis during sedation for imaging in pediatric patients. Patients < 18 years who had undergone whole-body magnetic resonance imaging (MRI) under sedation with propofol or dexmedetomidine were included in this study. The development of atelectasis was visually and quantitatively assessed by coronal short tau inversion recovery images of the thoracic level. Multivariable logistic regression was performed to identify the independent factors associated with the development of atelectasis. Ninety-one patients were included in the analysis. In the multivariable analysis, administration of supplemental oxygen was the only factor significantly associated with the occurrence of atelectasis (adjusted odds ratio, 4.84; 95% confidence interval, 1.48-15.83; p = 0.009). Univariable analysis showed that the use of dexmedetomidine was associated with a lower incidence of atelectasis; however, this could not be verified in the multivariable analysis. Among the pediatric patients who had undergone imaging under sedation, additional oxygen supplementation was the only independent factor associated with atelectasis occurrence. A prospective clinical trial is required to identify the cause-effect relationship between oxygen administration and occurrence of atelectasis during sedation.

Effectiveness of postural lung recruitment on postoperative atelectasis assessed by lung ultrasound in children undergoing lateral thoracotomy cardiac surgery with cardiopulmonary bypass

OBJECTIVES

To assess the effects of postural lung recruitment maneuvers on the postoperative atelectasis assessed by lung ultrasound (LUS) compared with supine position recruitment maneuvers in children undergoing right lateral thoracotomy cardiac surgery with cardiopulmonary bypass.

METHODS

In this randomized and controlled trial, 84 patients aged 3 years or younger, scheduled for right lateral thoracotomy cardiac surgery with cardiopulmonary bypass (CPB) were randomly allocated to postural lung recruitment group or control group. The first LUS exam was performed immediately upon completion of the cardiac surgery (T1), and a repeat ultrasound exam started 1 min after lung recruitment maneuvers (T2). The primary outcome was the incidence of significant atelectasis at T2.

RESULTS

The incidence of significant atelectasis at T2 in the postural lung recruitment maneuver group was lower compared with that in the control group (30.2% vs. 58.1%; odds ratio: 0.31; 95% confidence interval: 0.13-0.76; p = .009). The LUS scores for consolidations and B-lines of the left lung were higher than those of the right lung in both groups at T1. More significant reduction of the left LUS scores and sizes of atelectatic areas were found in the postural lung recruitment group than those in the control group.

CONCLUSIONS

Postoperative postural recruitment maneuver was more effective to improve reaeration of lung than supine position recruitment maneuver in children undergoing right lateral thoracotomy cardiac surgery with CPB.

Effect of spontaneous breathing on atelectasis during induction of general anaesthesia in infants: A prospective randomised controlled trial

BACKGROUND

Atelectasis occurs commonly during induction of general anaesthesia in children, particularly infants.

OBJECTIVES

We hypothesised that maintaining spontaneous ventilation can reduce atelectasis formation during anaesthetic induction in infants. We compared spontaneous ventilation and manual positive-pressure ventilation in terms of atelectasis formation in infants.

DESIGN

Randomised controlled study.

SETTING

Single tertiary hospital in Seoul, Republic of Korea, from November 2018 to December 2019.

PATIENTS

We enrolled 60 children younger than 1 year of age undergoing general anaesthesia, of whom 56 completed the study. Exclusion criteria were history of hypoxaemia during previous general anaesthesia, development of a respiratory tract infection within 1 month, current intubation or tracheostomy cannulation, need for rapid sequence intubation, preterm birth, age within 60 weeks of the postconceptional age and the presence of contraindications for rocuronium or sodium thiopental.

INTERVENTION

Patients were allocated randomly to either the 'spontaneous' group or 'controlled' group. During preoxygenation, spontaneous ventilation was maintained in the 'spontaneous' group while conventional bag-mask ventilation was provided in the 'controlled' group. After 5 min of preoxygenation, a lung ultrasound examination was performed to compare atelectasis formation in the two groups.

RESULTS

Atelectasis after preoxygenation was seen in seven (26.9%) of 26 patients in the 'spontaneous' group and 22 (73.3%) of 30 patients in the 'controlled' group (P = 0.001). The relative risk of atelectasis in the 'spontaneous' group was 0.39 (95% CI 0.211 to 0.723). Regarding ultrasound pictures of consolidation, the total score and sum of scores in the dependent regions were significantly lower in the 'spontaneous' group than in the 'controlled' group (P = 0.007 and 0.001, respectively).

CONCLUSION

Maintaining spontaneous ventilation during induction of general anaesthesia has a preventive effect against atelectasis in infants younger than 1 year of age, particularly in the dependent portions of the lungs.

TRIAL REGISTRATION

Clinicaltrials.gov (identifier: NCT03739697).

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 ± 3.8 vs. 3.5 ± 3.3 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 ± 3.2 and 1.8 ± 2.3, 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 ± 3.1) when compared with the CPAP group (0.5 ± 1.5; 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.

Application of a High-Flow Nasal Cannula for Prevention of Postextubation Atelectasis in Children Undergoing Surgery: A Randomized Controlled Trial

BACKGROUND

General anesthesia-induced atelectasis is common, and persistent postoperative atelectasis is associated with pulmonary complications. We aimed to evaluate the preventive effects of a high-flow nasal cannula (HFNC) on postoperative atelectasis and respiratory complications in infants and small children.

METHODS

In this prospective randomized controlled trial, children (≤2 years) receiving general anesthesia (>2 hours) were randomized into the control and HFNC groups. At the end of the surgery, the first lung ultrasound evaluation was performed in both groups. In the postanesthetic care unit (PACU), the control group received conventional oxygen therapy, while the HFNC group received oxygen via HFNC, with a flow rate of 2 L kg-1 min-1. Before discharge to the ward, a second lung ultrasound examination was performed. The primary outcome was the lung ultrasound score at PACU discharge. The secondary outcomes included the lung ultrasound score at the end of surgery, the incidence of significant atelectasis at PACU discharge, and other postoperative outcomes.

RESULTS

Lung ultrasound score and the incidence of atelectasis at the end of surgery did not differ significantly between the control (n = 38) and HFNC (n = 40) groups. After staying in the PACU, both groups showed a reduced lung ultrasound score and atelectasis incidence. However, the HFNC group had a significantly lower consolidation score than the control group (0; interquartile range [IQR] = 0-1 vs 3; IQR = 2-4; P< .001). Additionally, none of the patients had significant atelectasis in the HFNC group, compared to 6 patients in the control group (0% vs 15.8%; odds ratio [OR] = 0.444; 95% confidence interval for OR, 0.343-0.575; P = .011). Incidence of desaturation (oxygen saturation [Spo2] ≤ 95%), postoperative complications, and the length of hospital stay did not differ between the groups.

CONCLUSIONS

Preventive use of HFNC after surgery improves the lung ultrasound score and reduces postoperative atelectasis compared to conventional oxygen therapy in infants and small children.

Atelectasis prevention during anaesthesia using high-flow nasal cannula therapy: A paediatric randomised trial using MRI images

BACKGROUND

Atelectasis frequently occurs early on during anaesthesia in children. We hypothesised that positive expiratory pressure (PEP) generated via high-flow nasal cannula (HFNC) could prevent atelectasis in non-intubated children under general anaesthesia. The objective was to compare the volume of atelectasis present in patients treated via HFNC to that of patients treated via a face bag-mask without PEP. The outcome used for this comparison was the ratio of the atelectasis volume to the total pulmonary volume.

METHODS

A prospective single-centre, single-blind, randomised trial was conducted in a tertiary hospital from November 2018 through May 2019. The trial subjects were infants and children between six months and six years of age who required anaesthesia for an MRI. The children were randomised to receive sevoflurane for maintenance of anaesthesia either via a classic face bag-mask or by HFNC. The atelectasis volume was measured from thoracic MRI images. The judgement criterion was the ratio of the atelectasis volume to the lung volume.

RESULTS

Of a trial group of 42 patients, 21 received anaesthesia via a face bag-mask and 21 via HFNC. After three patients were excluded for technical issues, the data for 39 patients were analysed. The atelectasis volume to the lung volume ratio in the HFNC group was significantly smaller than the ratio for the face bag-mask group (1.6% vs 6.8%, respectively; p=0.002).

CONCLUSION

HFNC was associated with a lower atelectasis lung ratio compared to using a face bag-mask during anaesthesia for children maintained with spontaneous ventilation. Registered on Clinicaltrials.gov: NCT03592589.

Drug selection for sedation and general anesthesia in children undergoing ambulatory magnetic resonance imaging

The demand for drug-induced sedation for magnetic resonance imaging (MRI) scans have substantially increased in response to increases in MRI utilization and growing interest in anxiety in children. Understanding the pharmacologic options for deep sedation and general anesthesia in an MRI environment is essential to achieve immobility for the successful completion of the procedure and ensure rapid and safe discharge of children undergoing ambulatory MRI. For painless diagnostic MRI, a single sedative/anesthetic agent without analgesia is safer than a combination of multiple sedatives. The traditional drugs, such as chloral hydrate, pentobarbital, midazolam, and ketamine, are still used due to the ease of administration despite low sedation success rate, prolonged recovery, and significant adverse events. Currently, dexmedetomidine, with respiratory drive preservation, and propofol, with high effectiveness and rapid recovery, are preferred for children undergoing ambulatory MRI. General anesthesia using propofol or sevoflurane can also provide predictable rapid time to readiness and scan times in infant or children with comorbidities. The selection of appropriate drugs as well as sufficient monitoring equipment are vital for effective and safe sedation and anesthesia for ambulatory pediatric MRI.

Thoracic Magnetic Resonance Imaging Applications in Children

Lung pathologies in the pediatric population can usually be detected using chest radiography. Multidetector computed tomography (MDCT) imaging is often used as a supplementary method in the evaluation of lung diseases. Recently, magnetic resonance imaging (MRI) techniques were found to be reliable in the evaluation of pulmonary diseases in the pediatric population. This review study describes the routine application of MRI examinations and the use of thoracic MRI with a particular focus in pediatric patients.

Effect of an ultrasound-guided lung recruitment manoeuvre on postoperative atelectasis in children: A randomised controlled trial

BACKGROUND

Ultrasound-guided alveolar recruitment, regardless of the technique, could be more effective because it facilitates real-time monitoring of the expansion of collapsed alveoli.

OBJECTIVES

To evaluate and compare the effects of an ultrasound-guided lung recruitment manoeuvre with those of a conventional recruitment manoeuvre on the occurrence of postoperative atelectasis and clinical outcomes in children.

DESIGN

A randomised controlled trial.

SETTING

Tertiary children's hospital.

PATIENTS

Children aged 6 years or less.

INTERVENTION

Children scheduled for simple, superficial procedures underwent lung ultrasound after tracheal intubation (T1), at the end of surgery (T2) and before discharge from the postanaesthesia care unit (T3). Following lung ultrasound evaluation at T1 and T2, the conventional recruitment manoeuvre with a maximal airway pressure of 30 cmH2O was performed in the control group, while an ultrasound-guided recruitment manoeuvre was performed in the ultrasound group.

MAIN OUTCOME MEASURES

The primary outcome was the incidence of significant atelectasis at T3.

RESULTS

The incidences of atelectasis at T3 were 20.9 and 11.6% in the control (n = 43) and ultrasound groups (n = 43), respectively (odds ratio [OR], 2.012; 95% confidence interval [CI], 0.614 to 6.594; P = 0.249). The lung ultrasound scores were better in the ultrasound group than in the control group at T2 and T3, and the incidence of postoperative desaturation was higher in the control group than in the ultrasound group (16.3 vs. 2.3%; OR, 0.12; 95% CI 0.01 to 1.04; P = 0.05). The median airway pressure required for full lung expansion in the ultrasound group was 35 cmH2O at T1 and T2. Other postoperative outcomes were similar between groups.

CONCLUSION

Ultrasound-guided lung recruitment may be more effective than the conventional procedure in terms of the prevention of intra-operative atelectasis and postoperative desaturation; however, its beneficial effects on postoperative atelectasis remain unclear. An inspiratory airway pressure of more than 30 cmH2O is required for full recruitment of alveoli in healthy children.

CLINICAL TRIAL REGISTRY

ClinicalTrials.gov (NCT03453762).

Improving Quality of Chest Computed Tomography for Evaluation of Pediatric Malignancies

Introduction

Atelectasis is a problem in sedated pediatric patients undergoing cross-sectional imaging, impairing the ability to accurately interpret chest computed tomography (CT) imaging for the presence of malignancy, often leading to additional maneuvers and/or repeat imaging with additional radiation exposure.

Methods

A quality improvement team established a best-practice protocol to improve the quality of thoracic CT imaging in young patients with suspected primary or metastatic pulmonary malignancy. The specific aim was to increase the percentage of chest CT scans obtained for the evaluation of pulmonary nodules with acceptable atelectasis scores (0-1) in patients aged 0-5 years with malignancy, from a baseline of 45% to a goal of 75%.

Results

A retrospective cohort consisted of 94 patients undergoing chest CT between February 2014 and January 2015 before protocol implementation. The prospective cohort included 195 patients imaged between February 2015 and April 2018. The baseline percentage of CT scans that were scored 0 or 1 on the atelectasis scale was 44.7%, which improved to 75% with protocol implementation. The mean atelectasis score improved from 1.79 (±0.14) to 0.7 (±0.09). Sedation incidence decreased substantially from 73.2% to 26.5% during the study period.

Conclusions

Using quality improvement methodology including standardization of care, the percentage of children with atelectasis scores of 0-1 undergoing cross-sectional thoracic imaging improved from 45% to 75%. Also, eliminating the need for sedation in these patients has further improved image quality, potentially allowing for optimal detection of smaller nodules, and minimizing morbidity.

Effect of different fraction of inspired oxygen on development of atelectasis in mechanically ventilated children: A randomized controlled trial

BACKGROUND

The use of high fraction of inspired oxygen (F_I O₂ ) can cause direct pulmonary toxicity and pulmonary complications. The purpose of this study was to evaluate the effect of different F_I O₂ on development of intraoperative atelectasis in mechanically ventilated children using lung ultrasound.

METHODS

In this randomized controlled, patient- and sonographer-blinded trial, 86 children (≤6 years) undergoing noncardiac surgery were allocated into a low (n = 43) or high (n = 43) F_I O₂ group. The low F_I O₂ group consistently received 30% air-oxygen mixture during preoxygenation, ultrasound-guided recruitment maneuver, and mechanical ventilation. The high F_I O₂ group received 100% oxygen during preoxygenation and ultrasound-guided recruitment maneuver and 60% air-oxygen mixture during mechanical ventilation. Positive end-expiratory pressure of 5 cm H₂ O was applied in both groups. Lung ultrasound was performed one minute after the start of mechanical ventilation and at the end of surgery in both groups. Primary outcome was significant atelectasis incidence (consolidation score of ≥2 in any region) on the postoperative lung ultrasound. Secondary outcomes included significant atelectasis incidence on the preoperative lung ultrasound, incidences of intra- and postoperative desaturation, and incidences of postoperative fever and postoperative pulmonary complications.

RESULTS

Significant atelectasis incidence on the postoperative lung ultrasound was similar between the low and high F_I O₂ groups (28% vs 37%; Pearson chi-square value = 0.847; P = .357; OR 1.531; 95% CI 0.617-3.800). Significant atelectasis incidence on the preoperative lung ultrasound was also similar between the groups (12% vs 9%; Pearson chi-square value = 0.124; P = .725; OR 0.779; 95% CI 0.194-3.125). There were no statistically significant differences in the other secondary outcomes.

CONCLUSIONS

F_I O₂ did not affect significant atelectasis formation in mechanically ventilated children who received ultrasound-guided recruitment maneuver and positive end-expiratory pressure.

The usefulness of respiratory ultrasound assessment for modifying the physiotherapeutic algorithm in children after congenital heart defect surgeries

Background

The aim of the study was to assess the effectiveness and the possible use of diagnostic transthoracic ultrasound of the respiratory tract to qualify patients for therapy and to monitor the effectiveness of physiotherapy in children after cardiac surgeries.

Materials and methods

A total of 103 patients aged between 1 and 12 months who underwent a series of congenital heart surgeries using cardiopulmonary bypass were qualified for the prospective analysis. Point-of-care respiratory ultrasound imaging was performed according to a tailored protocol during the patient’s stay in the intensive care unit. In order to evaluate the method, the obtained findings were subject to comparative analysis against the available radiographic findings with a division into sectors.

Results

The comparative analysis of ultrasonographic and radiographic findings with a division into sectors showed the highest concordance rate (89.6%) for S1L (the apex of the left lung) and the lowest concordance rate (57.0%) for S2L (pericardial region). The highest discordance rate, i.e. when a lesion was detected in radiography (X-ray = 1), but was not confirmed by ultrasound (US = 0), was reported for sectors S1P (right lung apex) – 26.1%, and S2L – 40.0%, whereas the lowest discordance rate was reported for S1L – 7.0%. The highest discordance rate, i.e. when a lesion was shown in ultrasound (US = 1), but was not confirmed by radiography (X-ray = 0) was reported for S3P (the base of the right lung) and S3L (base of the right lung) – 28.3% and 26.1%, respectively.

Conclusions

The author’s protocol for ultrasonographic assessment of the respiratory tract is an optimal tool for determining therapeutic goals, as well as for the assessment of the efficacy of pulmonary physiotherapy. The diagnostic value of ultrasonographic assessment of the respiratory tract and standard radiography in the study group depends on the location of the investigated lung segment.

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.

Electronic supplementary material

The online version of this article (doi:10.1186/s13089-017-0073-0) contains supplementary material, which is available to authorized users.

Doppler images of intra-pulmonary shunt within atelectasis in anesthetized children

BACKGROUND

Doppler images of pulmonary vessels in pulmonary diseases associated with subpleural consolidations have been described. Color Doppler easily identifies such vessels within consolidations while spectral Doppler analysis allows the differentiation between pulmonary and bronchial arteries. Thus, Doppler helps in diagnosing the nature of consolidations. To our knowledge, Doppler analysis of pulmonary vessels within anesthesia-induced atelectasis has never been described before. The aim of this case series is to demonstrate the ability of lung ultrasound to detect the shunting of blood within atelectatic lung areas in anesthetized children.

FINDINGS

Three anesthetized and mechanically ventilated children were scanned in the supine position using a high-resolution linear probe of 6-12 MHz. Once subpleural consolidations were detected in the most dependent posterior lung regions, the probe was rotated such that its long axis followed the intercostal space. In this oblique position, color Doppler mapping was performed to detect blood flow within the consolidation. Thereafter, pulsed waved spectral Doppler was applied in the previously identified vessels during a short expiratory pause, which prevented interferences from respiratory motion. Different flow patterns were identified which corresponded to both, pulmonary and bronchial vessels. Finally, a lung recruitment maneuver was performed which leads to the complete resolution of the aforementioned consolidation thereby confirming the pathophysiological entity of anesthesia-induced atelectasis.

CONCLUSIONS

Lung ultrasound is a non-invasive imaging tool that not only enables the diagnosis of anesthesia-induced atelectasis in pediatric patients but also analysis of shunting blood within this consolidation.

Does preparation of children before MRI reduce the need for anesthesia? Prospective randomized control trial

BACKGROUND

Magnetic resonance imaging has been recognized for years as the safest and most precise imaging method, particularly for children. The accuracy of MRI depends on avoidance of patient movement during the study. This may be difficult for children and may require anesthesia.

OBJECTIVE

We evaluated an introductory instruction program as an assistive tool in performing MRI without anesthesia.

MATERIALS AND METHODS

In one institution, 121 children were randomized to undergo full interactive pre-MRI instruction (n=64), which included an instructional booklet, movie and simulator practice, or partial instruction (n=57), comprised of the booklet only. All researchers and health care professionals involved, except for the one who instructed the families, were masked to the group allocation. Parents' anxiety, according to the Spielberger state anxiety inventory, was measured.

RESULTS

Median age was 7.4 years (range: 5 years-16 years). Anesthesia was required for fewer children who received full compared to partial instruction: 17 (27%) vs. 27 (47%), P≤0.02. The median anxiety level prior to instruction was higher than the median level after instruction, for both the partial and full instruction groups.

CONCLUSION

Instruction including simulator practice was associated with a decreased need for anesthesia among children undergoing MRI scans.

Does preparation of children before MRI reduce the need for anesthesia? Prospective randomized control trial

BACKGROUND

Magnetic resonance imaging has been recognized for years as the safest and most precise imaging method, particularly for children. The accuracy of MRI depends on avoidance of patient movement during the study. This may be difficult for children and may require anesthesia.

OBJECTIVE

We evaluated an introductory instruction program as an assistive tool in performing MRI without anesthesia.

MATERIALS AND METHODS

In one institution, 121 children were randomized to undergo full interactive pre-MRI instruction (n=64), which included an instructional booklet, movie and simulator practice, or partial instruction (n=57), comprised of the booklet only. All researchers and health care professionals involved, except for the one who instructed the families, were masked to the group allocation. Parents' anxiety, according to the Spielberger state anxiety inventory, was measured.

RESULTS

Median age was 7.4 years (range: 5 years-16 years). Anesthesia was required for fewer children who received full compared to partial instruction: 17 (27%) vs. 27 (47%), P≤0.02. The median anxiety level prior to instruction was higher than the median level after instruction, for both the partial and full instruction groups.

CONCLUSION

Instruction including simulator practice was associated with a decreased need for anesthesia among children undergoing MRI scans.

Comparison of sevoflurane administered through a face mask versus rectal thiopental sodium in children undergoing magnetic resonance imaging

OBJECTIVE

Sevoflurane (S) and thiopental sodium (T) are commonly used to produce sedation for routine MRI procedures. However, to date there have been no comparative studies evaluating both techniques. We herein present the firt study comparing S and T techniques for pediatric sedation in MRI procedures.

MATERIALS AND METHODS

21 children, aged from 3 months to 6 years, scheduled for MRI were randomly assigned to either S or T group. Sedation performed under spontaneous respiration was induced with inspired 1-8% S in oxigen by face mask connected to a Mapleson C circuit or T (25 mg/kg) administered in distal rectum by cannula. The observed parameters included: time for induction, MRI time, first movement activity postprocedure and recovery time; MRI pauses from patient movement; technique failure, quality of the study, emergence agitation, critical events; and parental and radiologist satisfaction.

RESULTS

S compared with T showed significantly shorter anesthesia induction time (1.93 ± 0.7 versus 13.5 ± 2.6 min), first movement time (3.38 ± 1.2 versus 5.9 ± 2.1 min), recovery time (6.8 ± 1.6 versus 10.14 ± 3.3 min), and discharge MRI time (27.83 ± 5.1 versus 47.5 ± 8.7 min). There were fewer pauses during MRI from patient movement in S versus T (0 versus 3). The radiologists reported good quality and satisfaction scores in both groups. There were less behavioral disturbances in T group compared with S group (1 versus 3). There were no critical events in either group. There were no differences in parental satisfaction in both groups.

CONCLUSIONS

Sevoflurane shortens the induction and recovery time, enabling earlier discharge. Sevoflurane and rectal thiopental sodium protocols are safe and effective, providing adequate conditions for MRI in pediatric outpatients, although rectal thiopental is more unpredictable.

Pediatric Chest MR Imaging: Sedation, Techniques, and Extracardiac Vessels

Thoracic MR imaging in the pediatric population provides unique challenges requiring tailored protocols and a practical approach to pediatric issues, such as patient motion and sedation. Concern regarding the use of ionizing radiation in the pediatric population has continued to advance the use of MR imaging despite these challenges. This article provides a practical approach to thoracic vascular MR imaging with special attention paid to pediatric-specific issues such as sedation. Thoracic vascular anatomy and pathology are discussed with an emphasis on protocols that can facilitate accurate diagnosis.

Lung recruitment manoeuvres do not cause haemodynamic instability or oxidative stress but improve oxygenation and lung mechanics in a newborn animal model: an observational study

BACKGROUND

Lung recruitment manoeuvres in neonates during anaesthesia are not performed routinely due to concerns about causing barotrauma, haemodynamic instability and oxidative stress.

OBJECTIVE

To assess the influence of recruitment manoeuvres and positive end-expiratory pressure (PEEP) on haemodynamics, oxidative stress, oxygenation and lung mechanics.

DESIGN

A prospective experimental study.

SETTING

Experimental Unit, La Paz University Hospital, Madrid, Spain.

ANIMALS

Eight newborn piglets (<48 h) with healthy lungs under general anaesthesia.

INTERVENTIONS

The recruitment manoeuvres in pressure-controlled ventilation (PCV) were performed along with a constant driving pressure of 15 cmH2O. After the recruitment manoeuvres, PEEP was reduced in a stepwise fashion to find the maximal dynamic compliance step (maxCDyn-PEEP). Blood oxidative stress biomarkers (lipid peroxidation products, protein carbonyls, total glutathione, oxidised glutathione, reduced glutathione and activity of glutathione peroxidase) were analysed.

MAIN OUTCOME MEASURES

Haemodynamic parameters, arterial partial pressure of oxygen (paO2), tidal volume (Vt), dynamic compliance (Cdyn) and oxidative stress biomarkers were measured.

RESULTS

The recruitment manoeuvres did not induce barotrauma. Haemodynamic instability was not detected either in the maximum pressure step (overdistension step 5) or during the entire process. No substantial differences were observed in blood oxidative stress parameters analysed as compared with their baseline values (with 0 PEEP) or the values obtained 180 min after the onset of the recruitment manoeuvres (optimal PEEP). Significant maximal values were achieved in step 14 with an increase in paO2 (32.43 ± 8.48 vs. 40.39 ± 15.66 kPa; P = 0.037), Vt (47.75 ± 13.59 vs. 73.87 ± 13.56 ml; P = 0.006) and Cdyn (2.50 ± 0.64 vs. 4.75 ± 0.88 ml cmH2O; P < 0.001). Maximal dynamic compliance step (maxCdyn-PEEP) was 2 cmH2O.

CONCLUSION

Recruitment manoeuvres in PCV with a constant driving pressure are a well tolerated open-lung strategy in a healthy-lung neonatal animal model under general anaesthesia. The recruitment manoeuvres improve oxygenation parameters and lung mechanics and do not cause barotrauma, haemodynamic instability or oxidative stress.

Propofol anesthesia for children undergoing magnetic resonance imaging: a comparison with isoflurane, nitrous oxide, and a laryngeal mask airway

BACKGROUND

Both propofol infusions with oxygen delivered through nasal cannula and isoflurane/N2O (nitrous oxide) delivered via a laryngeal mask airway (LMA) are used to provide anesthesia for children undergoing magnetic resonance imaging scans. We compared the incidence of adverse events and perioperative physiologic responses in children anesthetized with these 2 regimens.

METHODS

One hundred-fifty healthy children, ages 1 to 10 years, were randomized to receive either a propofol infusion (starting at 300 µg kg·min) with oxygen via nasal cannula (n = 75) or isoflurane with 70% N2O in oxygen delivered via an LMA (n = 75), both after a sevoflurane/N2O/oxygen induction. Adverse airway events, as well as hemodynamic, respiratory, and other physiologic responses were recorded during the magnetic resonance imaging scans and in the postanesthesia care unit by a single research nurse who was blind to the treatments. All parents were contacted postoperatively to complete a postanesthetic follow-up.

RESULTS

All 150 children completed their scans. The frequency of all adverse airway events during emergence and recovery after propofol (12%) was significantly less than that after isoflurane/N2O/LMA (49%) (95% confidence interval for the risk difference was 23%-50%) (P = 0.0001). Hemodynamic responses and recovery times for the 2 treatments were similar. Early recovery, defined as the time interval from admission to the postanesthesia care unit until eye opening and wakefulness (modified Aldrete score >5), after propofol was more rapid than that after isoflurane/N2O/LMA (P = 0.0001 and P = 0.0012, respectively). No scans had to be repeated.

CONCLUSIONS

The frequency of adverse airway events during emergence and recovery after propofol infusion with oxygen by nasal cannula is less than with isoflurane/N2O/LMA in children.

The radiological diagnosis of pneumonia in children

Despite the importance of paediatric pneumonia as a cause of short and long-term morbidity and mortality worldwide, a reliable gold standard for its diagnosis remains elusive. The utility of clinical, microbiological and radiological diagnostic approaches varies widely within and between populations and is heavily dependent on the expertise and resources available in various settings. Here we review the role of radiology in the diagnosis of paediatric pneumonia. Chest radiographs (CXRs) are the most widely employed test, however, they are not indicated in ambulatory settings, cannot distinguish between viral and bacterial infections and have a limited role in the ongoing management of disease. A standardised definition of alveolar pneumonia on a CXR exists for epidemiological studies targeting bacterial pneumonias but it should not be extrapolated to clinical settings. Radiography, computed tomography and to a lesser extent ultrasonography and magnetic resonance imaging play an important role in complicated pneumonias but there are limitations that preclude their use as routine diagnostic tools. Large population-based studies are needed in different populations to address many of the knowledge gaps in the radiological diagnosis of pneumonia in children, however, the feasibility of such studies is an important barrier.

Pressure safety range of barotrauma with lung recruitment manoeuvres: a randomised experimental study in a healthy animal model

CONTEXT

Recruitment manoeuvres aim at reversing atelectasis during general anaesthesia but are associated with potential risks such as barotrauma.

OBJECTIVE

To explore the range of pressures that can be used safely to fully recruit the lung without causing barotrauma in an ex-vivo healthy lung rabbit model.

DESIGN

Prospective, randomised, experimental study.

SETTING

Experimental Unit, La Paz University Hospital, Madrid, Spain.

ANIMALS

Fourteen healthy young New Zealand rabbits of 12 weeks of age.

INTERVENTIONS

Animals were euthanised, the thorax and both pleural spaces were opened and the animals were allocated randomly into one of two groups submitted to two distinct recruitment manoeuvre strategies: PEEP-20 group, in which positive end-expiratory pressure (PEEP) was increased in 5-cmH2O steps from 0 to 20 cmH2O and PEEP-50 group, in which PEEP was increased in 5-cmH2O steps from 0 to 50 cmH2O. In both groups, a driving pressure of 15 cmH2O was maintained until maximal PEEP and its corresponding maximal inspiratory pressures (MIPs) were reached. From there on, driving pressure was progressively increased in 5-cmH2O steps until detectable barotrauma occurred. Two macroscopic conditions were defined: anatomically open lung and barotrauma.

MAIN OUTCOME MEASURES

We measured open lung and barotrauma MIP, PEEP and driving pressure obtained using each strategy. A pressure safety range, defined as the difference between barotrauma MIP and anatomically open lung MIP, was also determined in both groups.

RESULTS

Open lung MIP was similar in both groups: 23.6 ± 3.8 and 23.3 ± 4.1 cmH2O in the PEEP-50 and PEEP-20 groups, respectively (P = 0.91). However, barotrauma MIP in the PEEP-50 group was higher (65.7 ± 3.4 cmH2O) than in the PEEP-20 group (56.7 ± 5 0.2 cmH2O) (P = 0.003) resulting in a safety range of pressures of respectively 33.3 ± 8.7 and 42.1 ± 3.9 cmH2O (P = 0.035).

CONCLUSION

In this ex-vivo model, we found a substantial difference between recruitment and barotrauma pressures using both recruitment strategies. However, a higher margin of safety was obtained when a higher PEEP and lower driving pressure strategy was used for recruiting the lung.

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.

Qualitative and quantitative interpretation of computed tomography of the lungs in healthy neonatal foals

OBJECTIVE

To qualitatively describe lung CT images obtained from sedated healthy equine neonates (≤ 14 days of age), use quantitative analysis of CT images to characterize attenuation and distribution of gas and tissue volumes within the lungs, and identify differences between lung characteristics of foals ≤ 7 days of age and foals > 7 days of age.

ANIMALS

10 Standardbred foals between 2.5 and 13 days of age.

PROCEDURES

Foals were sedated with butorphanol, midazolam, and propofol and positioned in sternal recumbency for thoracic CT. Image analysis software was used to exclude lung from nonlung structures. Lung attenuation was measured in Hounsfield units (HU) for analysis of whole lung and regional changes in attenuation and lung gas and tissue components. Degree of lung attenuation was classified as follows: hyperinflated or emphysema, -1,000 to -901 HU; well aerated, -900 to -501 HU; poorly aerated, -500 to -101 HU; and nonaerated, > -100 HU.

RESULTS

Qualitative evidence of an increase in lung attenuation and patchy alveolar patterns in the ventral lung region were more pronounced in foals ≤ 7 days of age than in older foals. Quantitative analysis revealed that mean ± SD lung attenuation was greater in foals ≤ 7 days of age (-442 ± 28 HU) than in foals > 7 days of age (-521 ± 24 HU). Lung aeration and gas volumes were lower than in other regions ventrally and in the mid lung region caudal to the heart. CONCLUSIONS AND CLINICAL RELEVANCE-Identified radiographic patterns and changes in attenuation were most consistent with atelectasis and appeared more severe in foals ≤ 7 days of age than in older neonatal foals. Recognition of these changes may have implications for accurate CT interpretation in sedated neonatal foals with pulmonary disease.

Infant cardiac magnetic resonance imaging using oscillatory ventilation: safe and effective

Cardiac magnetic resonance imaging (CMR) for infants and young children typically requires sedation. General anesthesia with controlled ventilation can eliminate motion artifact with breath-holds during imaging to limit respiratory artifact, but these may lead to atelectasis or other complications. High-frequency oscillatory ventilation (HFOV) provides ventilation with near-constant mean airway pressure and minimal movement of chest wall and diaphragm, thus obviating the need for breath-holding. Clinical data were collected for 8 infants who underwent CMR with HFOV and 8 controls who underwent CMR with conventional ventilator and breath-hold technique. Data included demographic information, adverse events, and scan-acquisition time. Studies were reviewed for image quality by two cardiologists who were blinded to type of ventilation. There were no significant differences in patient characteristics between the two groups. There was no significant difference in average image quality for cine short-axis or black blood imaging. Total CMR scan time was not significantly different between groups, but the short-axis cine stack was acquired more quickly in the HFOV group (1.8 ± 0.8 vs. 5.0 ± 3.6 min). There were no adverse events in the HFOV group, but scans were terminated early for two patients in the conventional ventilator group. HFOV during CMR is feasible and well tolerated. Image quality is equivalent to that obtained with conventional ventilation with breath-holding technique and allows shorter cine scan times for some sequences.

Abnormal MIBG uptake in a neuroblastoma patient with right upper lobe atelectasis

A 3-month-old boy with a history of an abdominopelvic neuroblastoma presented 1 week after tumor resection for a routine follow-up 123-I Meta-iodobenzylguanidine (MIBG) scan to assess for residual mass. The study demonstrated abnormal radiotracer uptake in the right upper lobe, which correlated on the SPECT/CT to an area of airspace consolidation thought to be secondary to atelectasis. To the best of our knowledge, there is one published case of MIBG radiotracer uptake in the lung correlating with pneumonia; however, there are no reported cases to date in the literature of focal pulmonary MIBG uptake corresponding to atelectasis.

MRI of the lung (2/3). Why … when … how?

BACKGROUND

Among the modalities for lung imaging, proton magnetic resonance imaging (MRI) has been the latest to be introduced into clinical practice. Its value to replace X-ray and computed tomography (CT) when radiation exposure or iodinated contrast material is contra-indicated is well acknowledged: i.e. for paediatric patients and pregnant women or for scientific use. One of the reasons why MRI of the lung is still rarely used, except in a few centres, is the lack of consistent protocols customised to clinical needs.

METHODS

This article makes non-vendor-specific protocol suggestions for general use with state-of-the-art MRI scanners, based on the available literature and a consensus discussion within a panel of experts experienced in lung MRI.

RESULTS

Various sequences have been successfully tested within scientific or clinical environments. MRI of the lung with appropriate combinations of these sequences comprises morphological and functional imaging aspects in a single examination. It serves in difficult clinical problems encountered in daily routine, such as assessment of the mediastinum and chest wall, and even might challenge molecular imaging techniques in the near future.

CONCLUSION

This article helps new users to implement appropriate protocols on their own MRI platforms. Main Messages • MRI of the lung can be readily performed on state-of-the-art 1.5-T MRI scanners. • Protocol suggestions based on the available literature facilitate its use for routine • MRI offers solutions for complicated thoracic masses with atelectasis and chest wall invasion. • MRI is an option for paediatrics and science when CT is contra-indicated.

Computed tomography score and pulmonary function in infants with chronic lung disease of infancy

Chronic lung disease of infancy (CLDI) remains a common outcome among infants born extremely prematurely. In older children and adults with lung disease, pulmonary function and computed tomography (CT) scores are used to follow up respiratory disease and assess disease severity. For infants and toddlers, however, these outcomes have been used very infrequently and most often, a dichotomous respiratory outcome (presence or absence of CLDI) is employed. We evaluated the performance of CT score and pulmonary function to differentiate infants and toddlers with CLDI from a control group. CT scans, forced expiratory flows and pulmonary diffusing capacity were obtained in 39 CLDI patients and 41 controls (aged 4-33 months). CT scans were quantified using a scoring system, while pulmonary function was expressed as Z-scores. CT score outperformed pulmonary function in identifying those with CLDI. There were no significant correlations between CT score and pulmonary function. CT score had a better performance than pulmonary function in differentiating individuals with CLDI; however, these outcomes may reflect differing components of the pulmonary pathophysiology of CLDI. This new information on pulmonary outcomes can assist in designing studies with these parameters. Future studies will be required to evaluate which of the outcomes can better detect improvement with therapeutic intervention and/or lung growth.