Performance of Lung Ultrasound in Detecting Peri-Operative Atelectasis after General Anesthesia

ESICM-ESPNIC international expert consensus on quantitative lung ultrasound in intensive care

PURPOSE

To provide an international expert consensus on technical aspects and clinical applications of quantitative lung ultrasound in adult, paediatric and neonatal intensive care.

METHODS

The European Society of Intensive Care (ESICM) and the European Society of Paediatric and Neonatal Intensive Care (ESPNIC) endorsed the project. We selected an international panel of 20 adult, paediatric and neonatal intensive care experts with clinical and research expertise in quantitative lung ultrasound, plus two non-voting methodologists. Fourteen clinical questions were proposed by the chairs to the panel, who voted for their priority (1-9 Likert-type scale) and proposed modifications/supplementing (two-round vote). All the questions achieved the predefined threshold (mean score > 5) and 14 groups of 3 mixed adult/paediatric experts were identified to develop the statements for each clinical question; predefined groups of experts in the fields of adult and paediatric/neonatal intensive care voted statements specific for these subgroups. An iterative approach was used to obtain the final consensus statements (two-round vote, 1-9 Likert-type scale); statements were classified as with agreement (range 7-9), uncertainty (4-6), disagreement (1-3) when the median score and ≥ 75% of votes laid within a specific range.

RESULTS

A total of 46 statements were produced (4 adults-only, 4 paediatric/neonatal-only, 38 interdisciplinary); all obtained agreement. This result was also achieved by acknowledging in the statements the current limitations of quantitative lung ultrasound.

CONCLUSION

This consensus guides the use of quantitative lung ultrasound in adult, paediatric and neonatal intensive care and helps identify the fields where further research will be needed in the future.

Effect of driving pressure-guided individualized positive end-expiratory pressure (PEEP) ventilation strategy on postoperative atelectasis in patients undergoing laparoscopic surgery as assessed by ultrasonography: study protocol for a prospective randomized controlled trial

BACKGROUND

Ventilator-induced lung injury caused by mechanical ventilation under general anesthesia as well as CO2 pneumoperitoneum and special positions for laparoscopy may increase the risk of postoperative pulmonary complications (PPCs). Lung protective ventilation under general anesthesia is advised by the guidelines to lower the risk of PPCs in surgical patients. However, there is considerable controversy about the optimal level of positive end-expiratory pressure (PEEP) and how to set it. Driving pressure reflects the overall respiratory stress and high driving pressure is an independent risk factor for PPCs. The purpose of this study is to explore whether driving pressure-guided individualized PEEP ventilation can lower the incidence of postoperative atelectasis by improving respiratory mechanics during laparoscopic surgery consequently lowering the incidence of PPCs compared with the traditional fixed PEEP ventilation strategy.

METHODS

The study will be a single-center, prospective, randomized controlled clinical study. A total of 106 adult patients with medium-to-high-risk PPCs undergoing laparoscopic surgery for more than 2 h will be randomly assigned in a 1:1 ratio to receive an individualized PEEP guided by minimum driving pressure (group D) or a fixed PEEP of 5 cmH2O (group C). Patients in group C will maintain a PEEP of 5 cmH2O throughout the whole process, and patients in group D will be administered individualized PEEP after the start of pneumoperitoneum to achieve minimum driving pressure until the end of the operation. The primary outcome is the LUS score at 24 h postoperatively. The secondary outcomes are the LUS scores at other time points, intraoperative respiratory mechanics and oxygenation index, incidence and specific types of PPCs at 7 days postoperatively.

DISCUSSION

This study will better evaluate the effect of individualized PEEP application guided by driving pressure on the incidence of postoperative atelectasis based on ultrasound assessment consequently the incidence of PPCs in patients undergoing prolonged laparoscopic surgery. The results may provide a clinical evidence for optimizing perioperative lung protection strategies.

TRIAL REGISTRATION

www.chictr.org.cn ChiCTR2300079041. Registered on December 25, 2023.

Regional lung ventilation during supraglottic and subglottic jet ventilation: A randomized cross-over trial

OBJECTIVE

Test the hypothesis that the center of ventilation, a measure of ventro-dorsal atelectasis, is posterior during supraglottic ventilation indicating better dependent-lung ventilation. Secondarily, we tested the hypothesis that supraglottic ventilation improves oxygenation and carbon dioxide elimination.

BACKGROUND

Supraglottic and subglottic jet ventilation are both used during laryngotracheal surgery. Supraglottic jet ventilation may better prevent atelectasis and provide superior ventilation.

DESIGN

Randomized, cross-over trial.

SETTING

Operating rooms.

PATIENTS

Patients having elective micro-laryngotracheal surgery.

INTERVENTIONS

Patients were sequentially ventilated for 5 min with one randomly selected type of jet ventilation before being switched to the alternative method.

MEASUREMENTS

Regional ventilation distribution was estimated using electrical impedance tomography, with arterial oxygenation and carbon dioxide partial pressures being simultaneously evaluated.

RESULTS

Thirty patients completed the study. There were no statistically significant or clinically meaningful differences in the center of ventilation with supraglottic and subglottic ventilation. However, ventilation with the supraglottic approach was about 4 % higher in the ventromedial lung region and about 4 % lower in the dorsal lung. Surprisingly, arterial blood oxygenation was considerably worse with supraglottic (173 [156, 199] mmHg) than subglottic ventilation (293 [244, 340] mmHg). Arterial carbon dioxide partial pressure was near 40 mmHg with each approach, although slightly lower with supraglottic jet ventilation.

CONCLUSION

The center of ventilation distribution, a measure of atelectasis, was similar with supraglottic and subglottic jet ventilation. Subglottic jet ventilation improved the dorsal-dependent lung region and provided superior arterial oxygenation. Both techniques effectively eliminated carbon dioxide, with the supraglottic approach demonstrating slightly superior efficacy.

Mapping Trends and Hotspots Regarding the Use of Lung Ultrasound in the Field of Anesthesiology: A Bibliometric Analysis of Global Research

Purpose

Lung ultrasound (LUS) is increasingly utilized in the field of anesthesiology due to its focused, quick application and the advantage of not exposing patients to ionizing radiation. This study aims to analyze the status and trends in this area from a macroscopic perspective.

Methods

A bibliometric analysis was conducted using the Web of Science (WoS) Core Collection. The analysis and visualization were performed using WoS, Excel, VOSviewer, and CiteSpace. Parameters such as publications, countries, institutions, journals, and keywords were analyzed.

Results

A total of 133 articles published over the last 10 years were analyzed to clarify the current status and future trends on the use of LUS in anesthesiology. The number of publications increased markedly from May 1, 2014, to April 30, 2024. China is the highest productive country, while the USA had the highest number of citations. In the institution, Seoul National University in South Korea published the most articles and had the highest number of citations. Kim Jin-Tae emerged as the most prolific and influential author. BMC Anesthesiology and the Journal of Cardiothoracic and Vascular Anesthesia were identified as the most popular journals in the field. Keywords such as "atelectasis", "mechanical ventilation", and "pulmonary complications" were closely related to the use of LUS in anesthesiology.

Conclusion

This study provides a comprehensive analysis of research on the use of LUS in anesthesiology, highlighting the growing interest in LUS and its relevance to pulmonary complications.

Effects of ultrasound-guided recruitment manoeuvres on postoperative pulmonary complications in laparoscopic bariatric surgery patients: study protocol for a randomised clinical trial

BACKGROUND

Lung ultrasound-guided alveolar recruitment manoeuvres (RMs) may reduce the lung ultrasound score. However, whether the use of this strategy can reduce the incidence of postoperative pulmonary complications (PPCs) in the adult obese population has not yet been tested.

METHODS/DESIGN

This is a single-centre, two-arm, prospective, randomised controlled trial. A total number of 476 obese patients scheduled for bariatric surgeries will be enrolled. They will be randomly assigned to receive either lung ultrasound-guided RMs (intervention group) or conventional RMs (control group) intraoperatively. The occurrence of PPCs will be recorded as the primary outcome.

DISCUSSION

To the best of our knowledge, this is the first trial to test the effect of lung ultrasound-guided RMs on PPCs. The results of this trial will support the anaesthesiologists in choosing a potentially more efficient method to perform RMs for bariatric surgery patients.

TRIAL REGISTRATION

www.chictr.org.cn ChiCTR2400080203. Registered on 23 January 2024.

Can the lung ultrasound score predict pulmonary complications after non-thoracic surgery in patients with blunt thoracic trauma: A single-center observational study

STUDY OBJECTIVE

Patients with blunt thoracic trauma have a high risk of developing postoperative pulmonary complications (PPCs). In this study, we aimed to identify the risk factors for PPCs after non-thoracic surgery in patients with blunt thoracic trauma and investigate the efficacy of perioperative lung ultrasound scores in predicting PPC occurrence.

DESIGN

Prospective observational study.

SETTING

A Chinese tertiary orthopedic hospital.

PARTICIPANTS

This observational study included 369 patients with blunt thoracic trauma who underwent surgery for pelvic and upper or lower extremity fractures.

INTERVENTIONS

Lung ultrasonography was performed pre- and postoperatively.

MEASUREMENTS

Patients were followed up for 1 week to assess PPCs and assigned to the PPC or non-PPC groups. We identified risk factors for PPCs using univariate and multivariate logistic regression analyses. The predictive value of these risk factors was evaluated using receiver operating characteristic (ROC) curves.

MAIN RESULTS

PPCs incidence was 36.58 %. The two groups differed significantly in Injury Severity Scores, American Society of Anesthesiologists (ASA) classification, chronic obstructive pulmonary disease, hydrothorax, preoperative hypoxemia, lung ultrasound score, preoperative hemoglobin level, intraoperative infusion volume, and Assess Respiratory Risk in Surgical Patients in Catalonia (ARISCAT) scores (P < 0.05). Independent risk factors for PPCs included ASA classification III, higher postoperative lung ultrasound scores, preoperative anemia, higher intraoperative infusion volume, and higher ARISCAT scores. ROC curve analysis revealed that postoperative lung ultrasound score (area under the curve [AUC]: 0.810, cutoff: 10), preoperative hemoglobin level (AUC: 0.627, cutoff: 97), intraoperative infusion volume (AUC: 0.701, cutoff: 886.51 mL/h) and ARISCAT score (AUC: 0.718, cutoff: 33) predicted postoperative outcomes effectively.

CONCLUSIONS

Postoperative lung ultrasound scores reliably predicted pulmonary complications after non-thoracic surgery in patients with blunt thoracic trauma. ASA classification III, preoperative anemia, excessive intraoperative fluid infusion, higher ARISCAT, and postoperative lung ultrasound scores were significant risk factors associated with PPCs.

TRIAL REGISTRATION

Clinical Trial Number: 1900023408. Registered on May 26, 2019.

The effects of laryngeal mask versus endotracheal tube on atelectasis after general anesthesia induction assessed by lung ultrasound: A randomized controlled trial

STUDY OBJECTIVE

This study aims to evaluate the impact of Supreme™ laryngeal masks versus endotracheal tubes on atelectasis during general anesthesia using lung ultrasound (LUS), and provide evidence for respiratory management.

DESIGN

A single-center, double-blind, randomized controlled trial was conducted.

SETTING

The study was conducted in both the operating room and the post-anesthesia care unit, with follow-up assessments performed in the ward.

PATIENTS

Enrollment included 180 cases undergoing non-laparoscopic surgeries in gynecology, urology, and orthopedic limb surgeries.

INTERVENTIONS

Patients were randomly assigned 1:1 to the endotracheal intubation or laryngeal mask group.

MEASUREMENTS

LUS scores were recorded across 12 lung regions at baseline, 15 min after airway establishment, at the end of surgery, and 30 min following airway removal. Outcome measures encompassed the oxygenation index, dynamic lung compliance, incidence of postoperative pulmonary complications, throat pain, and other postoperative complications assessed at 24 and 48 h postoperatively. The primary outcome focused on the LUS score in all 12 lung regions at 15 min after airway establishment.

MAIN RESULTS

Intention-to-treat analysis of 177 subjects revealed endotracheal intubation led to significantly higher LUS scores at 15 min {P < 0.001, mean difference 4.15 ± 0.60, 95% CI [2.97, 5.33]}, end of surgery (P < 0.001, mean difference 3.37 ± 0.68, 95% CI [2.02, 4.72]), and 30 min post-removal (P < 0.001, mean difference 2.63 ± 0.48, 95% CI [1.68, 3.58]). No major complications occurred in the two groups.

CONCLUSIONS

Compared to endotracheal intubation, laryngeal masks effectively reduce atelectasis formation and progression in gynecological, urological non-laparoscopic, and orthopedic limb surgeries. However, caution is warranted when generalizing these findings to surgeries with a higher risk of laryngeal mask leakage or obese patients. Additionally, the efficacy of laryngeal masks in reducing postoperative atelectasis remains uncertain when comprehensive monitoring of muscle relaxation and reversal therapy is employed.

Innovative integration of lung ultrasound and wearable monitoring for predicting pulmonary complications in colorectal surgery: A prospective study

BACKGROUND

Postoperative pulmonary complications (PPCs) are common in patients who undergo colorectal surgery. Studies have focused on how to accurately diagnose and reduce the incidence of PPCs. Lung ultrasound has been proven to be useful in preoperative monitoring and postoperative care after cardiopulmonary surgery. However, lung ultrasound has not been studied in abdominal surgeries and has not been used with wearable devices to evaluate the influence of postoperative ambulation on the incidence of PPCs.

AIM

To investigate the relationship between lung ultrasound scores, PPCs, and postoperative physical activity levels in patients who underwent colorectal surgery.

METHODS

In this prospective observational study conducted from November 1, 2019 to August 1, 2020, patients who underwent colorectal surgery underwent daily bedside ultrasonography from the day before surgery to postoperative day (POD) 5. Lung ultrasound scores and PPCs were recorded and analyzed to investigate their relationship. Pedometer bracelets measured the daily movement distance for 5 days post-surgery, and the correlation between postoperative activity levels and lung ultrasound scores was examined.

RESULTS

Thirteen cases of PPCs was observed in the cohort of 101 patients. The mean (standard deviation) peak lung ultrasound score was 5.32 (2.52). Patients with a lung ultrasound score of ≥ 6 constituted the high-risk group. High-risk lung ultrasound scores were associated with an increased incidence of PPCs after colorectal surgery (logistic regression coefficient, 1.715; odds ratio, 5.556). Postoperative movement distance was negatively associated with the lung ultrasound scores [Spearman's rank correlation coefficient (r), -0.356, P < 0.05].

CONCLUSION

Lung ultrasound effectively evaluates pulmonary condition post-colorectal surgery. Early ambulation and respiratory exercises in the initial two PODs will reduce PPCs and optimize postoperative care in patients undergoing colorectal surgery.

Comparison of lung aeration loss in open abdominal oncologic surgeries after ventilation with electrical impedance tomography-guided PEEP versus conventional PEEP: a pilot feasibility study

BACKGROUND

Existing literature lacks high-quality evidence regarding the ideal intraoperative positive end-expiratory pressure (PEEP) to minimize postoperative pulmonary complications (PPCs). We hypothesized that applying individualized PEEP derived from electrical impedance tomography would reduce the severity of postoperative lung aeration loss, deterioration in oxygenation, and PPC incidence.

METHODS

A pilot feasibility study was conducted on 36 patients who underwent open abdominal oncologic surgery. The patients were randomized to receive individualized PEEP or conventional PEEP at 4 cmH2O. The primary outcome was the impact of individualized PEEP on changes in the modified lung ultrasound score (MLUS) derived from preoperative and postoperative lung ultrasonography. A higher MLUS indicated greater lung aeration loss. The secondary outcomes were the PaO2/FiO2 ratio and PPC incidence.

RESULTS

A significant increase in the postoperative MLUS (12.0 ± 3.6 vs 7.9 ± 2.1, P < 0.001) and a significant difference between the postoperative and preoperative MLUS values (7.0 ± 3.3 vs 3.0 ± 1.6, P < 0.001) were found in the conventional PEEP group, indicating increased lung aeration loss. In the conventional PEEP group, the intraoperative PaO2/FiO2 ratios were significantly lower but not the postoperative ratios. The PPC incidence was not significantly different between the groups. Post-hoc analysis showed the increase in lung aeration loss and deterioration of intraoperative oxygenation correlated with the deviation from the individualized PEEP.

CONCLUSIONS

Individualized PEEP appears to protect against lung aeration loss and intraoperative oxygenation deterioration. The advantage was greater in patients whose individualized PEEP deviated more from the conventional PEEP.

Use of thoracic fluid content for prediction of fluid balance and postoperative pulmonary complications after major abdominal surgery: an observational study

BACKGROUND AND OBJECTIVES

The harmful effects of excess fluids frequently manifest in the lungs. Thoracic fluid content (TFC) is a variable provided by the STARLINGTM bioreactance monitor, which represents the total volume of fluid in the chest. The objective is to analyse the association between the variation in TFC values (TFCd0%) at 24 h postoperatively, postoperative fluid balance, and postoperative pulmonary complications.

MATERIAL AND METHODS

Prospective and analytical observational study. Patients scheduled for major abdominal surgery at a tertiary teaching hospital were included. They were monitored during the intervention and the first 24 postoperative hours with the monitor. STARLINGTM, measuring TFC and its variation in different stages of the perioperative period. Serial lung ultrasounds were performed and postoperative pulmonary complications were recorded. Logistic regression was performed to predict the occurrence of atelectasis and pulmonary congestion. The Pearson correlation coefficient was calculated to verify the association between TFC and fluid balance.

RESULTS

50 patients were analyzed. TFCd0% measured on the morning of the first postoperative day increased by a median of 27.1% [IQR: 20.3-37.5] and was correlated at r = 0.44 with the postoperative balance of 677 ml [IQR: 125.5-1,412]. Increased TFC was related to a higher risk of atelectasis (OR = 1.24) and pulmonary congestion (OR = 1.3).

CONCLUSIONS

TFCd0% measured 24 h after surgery presents a moderate correlation with postoperative fluid balance. Its increase is a risk factor for the appearance of postoperative pulmonary complications.

Randomized Controlled Trial Investigating the Impact of High-Flow Nasal Cannula Oxygen Therapy on Patients Undergoing Robotic-Assisted Laparoscopic Rectal Cancer Surgery, with a Post-Extubation Atelectasis as a Complication

Background

Utilizing high-flow nasal cannula (HFNC) oxygen therapy may prevent the collapse of alveoli and improve overall alveolar ventilation. In this study, we aimed to investigate the impact of HFNC on postoperative atelectasis in individuals undergoing robotic-assisted laparoscopic surgery.

Methods

Patients undergoing robotic-assisted laparoscopic surgery for rectal cancer were randomly assigned to the control or HFNC groups. After the surgical procedure was complete and the trachea was extubated, both groups underwent an initial lung ultrasound (LUS) scan. In the post-anesthesia care unit (PACU), the control group received conventional nasal cannula oxygen therapy, while the HFNC group received high-flow nasal cannula oxygen therapy. A second LUS scan was conducted before the patient was transferred to the ward. The primary outcome measured was the total LUS score at the time of PACU discharge.

Results

In the HFNC group (n = 39), the LUS score and the incidence of atelectasis at PACU discharge were significantly lower compared to the control group (n = 39) [(5 vs 10, P < 0.001), (48.72% vs 82.05%, P = 0.002)]. None of the patients in the HFNC group experienced hypoxemia in the PACU, whereas six patients in the control group did (P = 0.03). Additionally, the minimum SpO2 value in the PACU was notably higher in the HFNC group compared to the control group [99 vs 97, P < 0.001].

Conclusion

Based on the results, HFNC improves the extent of postoperative atelectasis and decreases the occurrence of atelectasis in individuals undergoing robotic-assisted laparoscopic surgery for rectal cancer.

Lung ultrasound for evaluating perioperative atelectasis and aeration in the post-anesthesia care unit

PURPOSE

Lung ultrasound is widely accepted as a reliable, noninvasive tool for evaluating lung status at the bedside. We assessed the impact of perioperative variables on atelectasis and lung aeration using lung ultrasound, and their correlation with postoperative oxygenation in patients undergoing general anesthesia.

METHODS

This prospective observational study evaluated 93 consecutive patients scheduled to undergo elective non-cardiothoracic surgery under general anesthesia. Lung ultrasound was performed 5 min after admission to the post-anesthesia care unit (PACU). Twelve pulmonary quadrants were selected for each ultrasound examination. The lung ultrasound scores and atelectasis status were calculated. The oxygenation assessment was obtained by arterial blood gas analysis before discharge from the PACU.

RESULTS

Thirty-two patients (34%) had atelectasis in at least one of the 12 evaluated segments, whereas 12 patients (13%) had atelectasis in at least three segments. The proportion of B-lines (≥ 3) and atelectasis in the inferolateral and posterior regions was significantly higher than in other regions. Patients with lung ultrasound scores ≥ 5 had a higher body mass index and lower PaO2 before discharge from the PACU than those with scores < 5. Patients with atelectasis had higher body mass indices and lung ultrasound scores. The presence of ≥ 2 regions of atelectasis was associated with lower PaO2. Using multivariate analysis, body mass index, intraoperative body position, and sex independently correlated with lung ultrasound scores. Age and lung ultrasound scores independently correlated with hypoxemia.

CONCLUSION

Lung ultrasound enables early postoperative evaluation of atelectasis and lung aeration, which are closely associated with postoperative oxygenation.

Lung Ultrasound Abnormalities in Patients Without Pulmonary Pathology Prior to Surgery

Background

The occurrence of lung ultrasound abnormalities in patients without lung disease remains uncertain, while patients with respiratory disease often exhibit such abnormalities.

Objectives

The primary aim was to identify pathological ultrasonographic pulmonary findings and their correlation with baseline diseases and static lung compliance in patients without any pre-existing respiratory conditions.

Methods

This prospective observational study enrolled a series of surgical patients with no history of pulmonary pathology (n = 104). Baseline diseases and patients' physical status classification, based on the American Society of Anesthesiologists (ASA), were documented by reviewing medical records. Prior to surgery, a lung ultrasound was performed to assess pulmonary changes. During surgery with general anesthesia, static lung compliance was measured. The Spearman correlation coefficient was employed to determine the correlation between the two variables.

Results

Twenty-four patients (23.07%) exhibited 1 - 2 B-lines in certain lung fields. Seven patients (6.7%) had an ultrasound B-line score > 0 (indicating ≥ 3 B-lines). Among these patients, the average number of lung fields with ≥ 3 B-lines was 3.71 ± 2.43. Patients with systemic diseases (ASA ≥ 2) displayed a higher number of B-lines compared to ASA I patients (P-value = 0.039). Pleural irregularities were found in 10 patients (9.6%), while atelectasis and pleural effusion were observed in five (4.8%) and four (3.8%) patients, respectively. The mean lung compliance value was 56.78 ± 15.33. No correlation was observed between the total score of the B-lines and lung compliance (Spearman's correlation: rho = -0.028, P-value = 0.812).

Conclusions

Patients without pulmonary pathology may exhibit ultrasound pulmonary abnormalities, which tend to increase with higher ASA scores and do not appear to have a correlation with static lung compliance.

Lung ultrasound score-based assessment of postoperative atelectasis in obese patients according to inspired oxygen concentration: A prospective, randomized-controlled study

BACKGROUND

According to a recent meta-analysis, in patients with a body mass index (BMI) ≥ 30, a high fraction of inhaled oxygen (FiO2) did not increase postoperative atelectasis. However, a high FiO2 generally increases the risk of postoperative atelectasis. Therefore, this study aimed to evaluate the effect of FiO2 on the development of atelectasis in obese patients using the modified lung ultrasound score (LUSS).

METHODS

Patients were assigned to 4 groups: BMI ≥ 30: group A (n = 21) and group B (n = 20) and normal BMI: group C (n = 22) and group D (n = 21). Groups A and C were administered 100% O2 during preinduction and emergence and 50% O2 during anesthesia. Groups B and D received 40% O2 for anesthesia. The modified LUSS was assessed before and 20 min after arrival to the postanesthesia care unit (PACU).

RESULTS

The difference between the modified LUSS preinduction and PACU was significantly higher in group A with a BMI ≥ 30 (P = .006); however, there was an insignificant difference between groups C and D in the normal BMI group (P = .076).

CONCLUSION

High FiO2 had a greater effect on the development of atelectasis in obese patients than did low FiO2; however, in normal-weight individuals, FiO2 did not have a significant effect on postoperative atelectasis.

The effects of laryngeal mask airway versus endotracheal tube on atelectasis in patients undergoing general anesthesia assessed by lung ultrasound: A protocol for a prospective, randomized controlled trial

Background

The incidence of atelectasis is high in patients undergoing general anesthesia. This may cause oxygenation impairment and further contribute to postoperative pulmonary complications (PPCs). As important airway management devices for general anesthesia, few studies have compared the effects of laryngeal mask airway (LMA) and endotracheal tube (ETT) on atelectasis. Additionally, lung ultrasound has been increasingly used for bedside atelectasis diagnosis. For the above considerations, this trial is designed to compare the effects of LMA and ETT on atelectasis assessed by lung ultrasound scores, further providing more powerful clinical evidence for perioperative respiratory management of non-laparoscopic elective lower abdominal surgery under general anesthesia.

Methods

This is a prospective, single-center, single-blind, randomized controlled trial. From July 2021 to July 2022, 180 patients undergoing elective non-laparoscopic lower abdominal surgery under general anesthesia will be recruited and randomly divided into the ETT and LMA groups at a ratio of 1:1. The primary outcome is the total atelectasis LUS of 12 lung regions 15 min after the establishment of the artificial airway. The total atelectasis LUS at the end of surgery and 30 min after extubation, oxygenation index, postoperative airway complications, PPCs, and length of stay will be analyzed as secondary indicators.

Trial registration

ClinicalTrials.gov identifier: ChiCTR1900020818. Registered on January 20, 2019. Registered with the name of “Laryngeal mask airway versus endotracheal tube for atelectasis.” URL: https://www.chictr.org.cn/showproj.aspx?proj=35143.

Effects of ultrasound-guided alveolar recruitment manoeuvres compared with sustained inflation or no recruitment manoeuvres on atelectasis in laparoscopic gynaecological surgery as assessed by ultrasonography: a randomized clinical trial

Background

The majority of patients may experience atelectasis under general anesthesia, and the Trendelenburg position and pneumoperitoneum can aggravate atelectasis during laparoscopic surgery, which promotes postoperative pulmonary complications. Lung recruitment manoeuvres have been proven to reduce perioperative atelectasis, but it remains controversial which method is optimal. Ultrasonic imaging can be conducive to confirming the effect of lung recruitment manoeuvres. The purpose of our study was to assess the effects of ultrasound-guided alveolar recruitment manoeuvres by ultrasonography on reducing perioperative atelectasis and to check whether the effects of recruitment manoeuvres under ultrasound guidance (visual and semiquantitative) on atelectasis are superior to sustained inflation recruitment manoeuvres (classical and widely used) in laparoscopic gynaecological surgery.

Methods

In this randomized, controlled, double-blinded study, women undergoing laparoscopic gynecological surgery were enrolled. Patients were randomly assigned to receive either lung ultrasound-guided alveolar recruitment manoeuvres (UD group), sustained inflation alveolar recruitment manoeuvres (SI group), or no RMs (C group) using a computer-generated table of random numbers. Lung ultrasonography was performed at four predefined time points. The primary outcome was the difference in lung ultrasound score (LUS) among groups at the end of surgery.

Results

Lung ultrasound scores in the UD group were significantly lower than those in both the SI group and the C group immediately after the end of surgery (7.67 ± 1.15 versus 9.70 ± 102, difference, -2.03 [95% confidence interval, -2.77 to -1.29], P < 0.001; 7.67 ± 1.15 versus 11.73 ± 1.96, difference, -4.07 [95% confidence interval, -4.81 to -3.33], P < 0.001;, respectively). The intergroup differences were sustained until 30 min after tracheal extubation (9.33 ± 0.96 versus 11.13 ± 0.97, difference, -1.80 [95% confidence interval, -2.42 to -1.18], P < 0.001; 9.33 ± 0.96 versus 10.77 ± 1.57, difference, -1.43 [95% confidence interval, -2.05 to -0.82], P < 0.001;, respectively). The SI group had a significantly lower LUS than the C group at the end of surgery (9.70 ± 1.02 versus 11.73 ± 1.96, difference, -2.03 [95% confidence interval, -2.77 to -1.29] P < 0.001), but the benefit did not persist 30 min after tracheal extubation.

Conclusions

During general anesthesia, ultrasound-guided recruitment manoeuvres can reduce perioperative aeration loss and improve oxygenation. Furthermore, these effects of ultrasound-guided recruitment manoeuvres on atelectasis are superior to sustained inflation recruitment manoeuvres.

Trial registration

Chictr.org.cn, ChiCTR2100042731, Registered 27 January 2021, www.chictr.org.cn.

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.

Effect of positive end expiratory pressure on atelectasis in patients undergoing major upper abdominal surgery under general anaesthesia: A lung ultrasonography study

Postoperative pulmonary complications vary in major upper abdominal surgery. The objective of this study was to assess the effect of positive end expiratory pressure on the incidence of atelectasis in patients undergoing major upper abdominal surgery under general anaesthesia using lung ultrasound. The patients were randomised into receiving either no positive end expiratory pressure (Group I) or positive end expiratory pressure of 5cm H₂O (Group II). Lung ultrasound was performed at various time points - baseline, 10 minutes, 2 hours after induction, during closure of skin and 30 minutes post extubation. The lung aeration as assessed by Total Modified Lung Ultrasound Score was worse in the Group I as compared to the Group II at 2 hours post induction. Driving pressure in Group II was significantly reduced compared to Group I. Application of positive end expiratory pressure, as minimal as 5cm H₂O, as a single intervention, helps in significantly reducing the Total Modified Lung Ultrasound Score after a duration of more than 2 hours and also attaining low driving pressures during intraoperative mechanical ventilation.

Perioperative lung ultrasonography in healthy horses undergoing general anesthesia for elective surgery

Background

Lung ultrasound (LUS) is poorly evaluated in horses, especially perioperatively.

Objectives

(1) Describe LUS findings in healthy horses before and after general anesthesia (GA), (2) evaluate if GA induces ultrasonographic changes in healthy horses, (3) suggest a LUS scoring system, (4) identify horse variables that are associated to LUS changes after anesthesia.

Animals

Twenty‐five healthy adult horses undergoing elective surgery.

Methods

Prospective hypothesis‐driven observational study. LUS findings were recorded before anesthesia, 5 minutes in recovery, 15 minutes, 2H, 3H, 4H, 6H, and 24H after anesthesia in 8 lung regions. Clinical data were collected perioperatively.

Results

There was a significant increase in amount of I‐lines (10.8 ± 8.7 vs 15.28 ± 8.19), B‐lines (3.2 ± 3.5 vs 8.72 ± 4.86), and coalescent B‐lines (0.04 ± 0.2 vs 1.12 ± 1.45) after anesthesia compared to before anesthesia, and a significantly higher LUS score 2H after anesthesia (4.92 ± 8.40) compared to before anesthesia (0.9 ± 1.8; P = .02). The maximal LUS score after anesthesia was correlated to total procedure time (Pearson r = 0.4, P = .05; Spearman r = 0.44, P = .03) and was significantly higher in horses with abnormal cardiorespiratory values during anesthesia (P = .005).

Conclusions

LUS changes can be induced by GA in healthy horses. This study did not investigate if and which LUS findings indicate lesions, however, this information can aid clinicians to identify pulmonary complications after anesthesia.

Effect of pressure controlled volume guaranteed ventilation during pulmonary resection in children

The purpose of the study was to evaluate the effect of pressure controlled volume guaranteed ventilation in children requiring one lung ventilation during pulmonary resection. Patients were randomly assigned to the lung protective ventilation combined with pressure controlled volume guaranteed group (PCV-VG group) or the lung protective ventilation combined with volume controlled ventilation group (VCV group). Both groups received tidal-volume ventilation of 8 ml kg⁻¹ body weight during two lung ventilation and 6 ml kg⁻¹ during OLV, with sustained 5 cmH₂O positive end-expiratory pressure. Data collections were mainly performed at 10 min after induction of anaesthesia during TLV (T1), 5 min after OLV initiation (T2) and 5 min after complete CO2 insufflations (T3). In total, 63 patients were randomly assigned to the VCV (n = 31) and PCV-VG (n = 32) groups. The PCV-VG group exhibited lower PIP than the VCV group at T1 (16.8 ± 2.3 vs. 18.7 ± 2.7 cmH₂O, P = 0.001), T2 (20.2 ± 2.7 vs. 22.4 ± 3.3 cmH₂O, P = 0.001), and T3 (23.8 ± 3.2 vs. 26.36 ± 3.7 cmH₂O, P = 0.01). Static compliance was higher in the PCV-VG group at T1, T2, and T3 (P = 0.01). After anaesthesia induction, lung aeration deteriorated, but with no immediate postoperative difference in both groups. Postoperative lung aeration improved and returned to normal from 2.5 h postextubation in both groups. PH was lower and PaCO₂ was higher in VCV group than PCV-VG group during one lung ventilation. No differences were observed in PaO₂-FiO₂-ratio at T2 and T3, the incidence of postoperative pulmonary complications, intraoperative desaturation and the length of hospital stay. In paediatric patients, who underwent pulmonary resection requiring one lung ventilation, PCV-VG was superior to VCV in its ability to provide lower PIP, higher static compliance and lower PaCO₂ at one lung ventilation during pneumothorax. However, its beneficial effects on different pathological situations in pediatric patients need more investigation.

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.

Assessment of Perioperative Atelectasis Using Lung Ultrasonography in Patients Undergoing Pneumoperitoneum Surgery in the Trendelenburg Position: Aspects of Differences according to Ventilatory Mode

BACKGROUND

During robotic gynecologic pneumoperitoneum surgery in the Trendelenburg position, aeration loss leads to perioperative atelectasis. Recently developed ventilator mode pressure-controlled ventilation volume-guaranteed (PCV-VG) mode could provide adequate ventilation with lower inspiratory pressure compared to volume-controlled ventilation (VCV); we hypothesized that PCV-VG mode may be beneficial in reducing perioperative atelectasis via low tidal volume (V_T) of 6 mL/kg ventilation during robotic gynecologic pneumoperitoneum surgery in the Trendelenburg position. We applied lung ultrasound score (LUS) for detecting perioperative atelectasis. We aimed to compare perioperative atelectasis between VCV and PCV-VG with a low V_T of 6 mL/kg during pneumoperitoneum surgery in the Trendelenburg position using LUS.

METHODS

Patients scheduled for robotic gynecologic surgery were randomly allocated to the VCV (n = 41) or PCV-VG group (n = 41). LUS, ventilatory, and hemodynamic parameters were evaluated at T1 (before induction), T2 (10 minutes after induction in the supine position), T3 (10 minutes after desufflation of CO₂ in the supine position), and T4 (30 minutes after emergence from anesthesia in the recovery room).

RESULTS

Eighty patients (40 with PCV-VG and 40 with VCV) were included. Demographic data showed no significant differences between the groups. The total LUS has changed from baseline to T4, 0.63 (95% confidence interval [CI], 0.32, 0.94) to 1.77 (95% CI, 1.42, 2.21) in the VCV group and 0.86 (95% CI, 0.56, 1.16) to 1.43 (95% CI, 1.08, 1.78) in the PCV-VG group (P = 0.170). In both groups, total LUS increased significantly compared to the baseline values.

CONCLUSION

Using a low V_T of 6 mL/kg during pneumoperitoneum surgery in the Trendelenburg position, our study showed no evidence that PCV-VG ventilation was superior to VCV in terms of perioperative atelectasis.

TRIAL REGISTRATION

Clinical Research Information Service Identifier: KCT0006404.

Lung Point-of-Care Ultrasound for Unexpected Hypoxemia during Anesthesia

This is a case report showing acute hypoxemia during anesthesia. Immediate differentiation using lung POCUS (point-of-care ultrasound), in addition to physical examination and portable chest radiography, was made. This is the first case report of sputum impaction due to pneumonia causing hypoxemia that has been detected by lung POCUS during anesthesia.

Pressure Support versus Spontaneous Ventilation during Anesthetic Emergence-Effect on Postoperative Atelectasis: A Randomized Controlled Trial

BACKGROUND

Despite previous reports suggesting that pressure support ventilation facilitates weaning from mechanical ventilation in the intensive care unit, few studies have assessed its effects on recovery from anesthesia. The authors hypothesized that pressure support ventilation during emergence from anesthesia reduces postoperative atelectasis in patients undergoing laparoscopic surgery using the Trendelenburg position.

METHODS

In this randomized controlled double-blinded trial, adult patients undergoing laparoscopic colectomy or robot-assisted prostatectomy were assigned to either the pressure support (n = 50) or the control group (n = 50). During emergence (from the end of surgery to extubation), pressure support ventilation was used in the pressure support group versus intermittent manual assistance in the control group. The primary outcome was the incidence of atelectasis diagnosed by lung ultrasonography at the postanesthesia care unit (PACU). The secondary outcomes were Pao2 at PACU and oxygen saturation measured by pulse oximetry less than 92% during 48 h postoperatively.

RESULTS

Ninety-seven patients were included in the analysis. The duration of emergence was 9 min and 8 min in the pressure support and control groups, respectively. The incidence of atelectasis at PACU was lower in the pressure support group compared to that in the control group (pressure support vs. control, 16 of 48 [33%] vs. 28 of 49 [57%]; risk ratio, 0.58; 95% CI, 0.35 to 0.91; P = 0.024). In the PACU, Pao2 in the pressure support group was higher than that in the control group (92 ± 26 mmHg vs. 83 ± 13 mmHg; P = 0.034). The incidence of oxygen saturation measured by pulse oximetry less than 92% during 48 h postoperatively was not different between the groups (9 of 48 [19%] vs. 11 of 49 [22%]; P = 0.653). There were no adverse events related to the study protocol.

CONCLUSIONS

The incidence of postoperative atelectasis was lower in patients undergoing either laparoscopic colectomy or robot-assisted prostatectomy who received pressure support ventilation during emergence from general anesthesia compared to those receiving intermittent manual assistance.

EDITOR’S PERSPECTIVE

Effects of positive end-expiratory pressure/recruitment manoeuvres compared with zero end-expiratory pressure on atelectasis in children: A randomised clinical trial

BACKGROUND

Atelectasis is a common postoperative complication. Peri-operative lung protection can reduce atelectasis; however, it is not clear whether this persists into the postoperative period.

OBJECTIVE

To evaluate to what extent lung-protective ventilation reduces peri-operative atelectasis in children undergoing nonabdominal surgery.

DESIGN

Randomised, controlled, double-blind study.

SETTING

Single tertiary hospital, 25 July 2019 to 18 January 2020.

PATIENTS

A total of 60 patients aged 1 to 6 years, American Society of Anesthesiologists physical status 1 or 2, planned for nonabdominal surgery under general anaesthesia (≤2 h) with mechanical ventilation.

INTERVENTIONS

The patients were assigned randomly into either the lung-protective or zero end-expiratory pressure with no recruitment manoeuvres (control) group. Lung protection entailed 5 cmH2O positive end-expiratory pressure and recruitment manoeuvres every 30 min. Both groups received volume-controlled ventilation with a tidal volume of 6 ml kg-1 body weight. Lung ultrasound was conducted before anaesthesia induction, immediately after induction, surgery and tracheal extubation, and 15 min, 3 h, 12 h and 24 h after extubation.

MAIN OUTCOME MEASURES

The difference in lung ultrasound score between groups at each interval. A higher score indicates worse lung aeration.

RESULTS

Patients in the lung-protective group exhibited lower median [IQR] ultrasound scores compared with the control group immediately after surgery, 4 [4 to 5] vs. 8 [4 to 6], (95% confidence interval for the difference between group values -4 to -4, Z = -6.324) and after extubation 3 [3 to 4] vs. 4 [4 to 4], 95% CI -1 to 0, Z = -3.161. This did not persist from 15 min after extubation onwards. Lung aeration returned to normal in both groups 3 h after extubation.

CONCLUSIONS

The reduced atelectasis provided by lung-protective ventilation does not persist from 15 min after extubation onwards. Further studies are needed to determine if it yields better results in other types of surgery.

TRIAL REGISTRATION

Chictr.org.cn (ChiCTR2000033469).

Optimal positive end-expiratory pressure to prevent anaesthesia-induced atelectasis in infants: A prospective, randomised, double-blind trial

BACKGROUND

Paediatric patients have a particularly high incidence of anaesthesia-induced atelectasis. Applying positive end-expiratory pressure (PEEP) with an alveolar recruitment manoeuvre has been substantially studied and adopted in adults; however, few studies have been conducted in children.

OBJECTIVE

We compared the effects of three levels of PEEP (3, 6 and 9 cmH2O) on anaesthesia-induced atelectasis measured by ultrasound in infants between 6 and 12 months of age who were undergoing general anaesthesia.

DESIGN

A prospective, randomised, double-blind trial.

SETTING

Department of Anaesthesia, single centre, South Korea, from May 2019 to March 2020.

PATIENTS

Children who were 6 to 12 months of age, whose American Society of Anesthesiologists (ASA) physical status was 1 or 2, whose height and weight were within two standard deviations of those of their peers, and who were scheduled for elective urological or general surgery were included in the study.

MAIN OUTCOME MEASURES

The primary outcome was the lung ultrasound score at the end of the procedure. The secondary outcomes included dynamic compliance, peak inspiratory pressure, driving pressure, cardiac index, mean arterial pressure and heart rate before and after applying PEEP.

RESULTS

The mean lung ultrasound score at the end of operation was 12.8 at PEEP 6 cmH2O and 12.1 at PEEP 9 cmH2O. Both were significantly lower than 18.4 at PEEP 3 cmH2O (P = 0.0002 and 0.00003, respectively). However, there was no significant difference between the scores of PEEP 6 cmH2O and PEEP 9 cmH2O. The Δ cardiac index (the cardiac index after PEEP - the cardiac index at 3 cmH2O of PEEP) was comparable among the three groups.

CONCLUSION

To reduce anaesthesia-induced atelectasis measured by ultrasound in healthy infants undergoing low abdominal, genitourinary or superficial regional operations, 6 cmH2O of PEEP was more effective than 3 cmH2O. PEEP of 9 cmH2O was comparable with 6 cmH2O.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT03969173.

Quantitative Lung Ultrasound: Technical Aspects and Clinical Applications

Lung ultrasound is increasingly used in emergency departments, medical wards, and critical care units-adult, pediatric, and neonatal. In vitro and in vivo studies show that the number and type of artifacts visualized change with lung density. This has led to the idea of a quantitative lung ultrasound approach, opening up new prospects for use not only as a diagnostic but also as a monitoring tool. Consequently, the multiple scoring systems proposed in the last few years have different technical approaches and specific clinical indications, adaptable for more or less time-dependent patients. However, multiple scoring systems may generate confusion among physicians aiming at introducing lung ultrasound in their clinical practice. This review describes the various lung ultrasound scoring systems and aims to clarify their use in different settings, focusing on technical aspects, validation with reference techniques, and clinical applications.

Perioperative high inspired oxygen fraction induces atelectasis in patients undergoing abdominal surgery: A randomized controlled trial

STUDY OBJECTIVE

We evaluated the feasibility of use and effects on postoperative atelectasis and complications of lower inspired oxygen fraction (FIO₂) compared to conventional oxygen therapy.

DESIGN

Single center, randomized clinical trial.

SETTING

University hospital, operating room and postoperative recovery area.

PATIENTS

One hundred ninety patients aged ≥50 with an American Society of Anesthesiologists physical status of I-III who underwent abdominal surgery with general anesthesia.

INTERVENTIONS

Participants were randomly assigned to either the low FIO₂ group (intraoperative: FIO₂ 0.35, during induction and recovery: FIO₂ 0.7) or the conventional FIO₂ group (intraoperative: FIO₂ 0.6, during induction and recovery: FIO₂ 1.0).

MEASUREMENTS

The primary outcome was postoperative atelectasis measured with lung ultrasonography at postoperative 30 min in the post-anesthesia care unit (consolidation score: each region 0-3, 12 region, total score range of 0 to 36, a lower score indicating better aeration).

MAIN RESULTS

Seven patients in the low FIO₂ group were omitted from the study due to changing FIO₂ during intervention (7/95 (8.4%) vs. 2/95 (2.1%), p = 0.088; low FIO₂ group vs. conventional FIO₂ group). Overall, atelectasis was detected in 29.7% (51/172) of patients 30 min after surgery by lung ultrasound and 40.1% (69/172) of patients after 2 days after surgery by chest X-ray. The scores of lung ultrasonography and the incidence of significant atelectasis (consolidation score ≥ 2 at any region) were lower in the low FIO₂ group than in the conventional FIO₂ group (median [IQR]: 3 [1,6] vs. 7 [3,9], p < 0.001 and 17/85 (20%) vs. 34/87 (39%), RR: 0.512 [95% CI: 0.311-0.843], p = 0.006, respectively). The incidence of surgical site infection and length of hospitalization were not significantly different between the two groups.

CONCLUSIONS

Based on our findings, decreased inspired oxygen fraction during anesthesia and recovery did not cause hypoxic events, but instead reduced immediate postoperative atelectasis. The use of intraoperative conventional higher inspired oxygen did not afford any clinical advantages for postoperative recovery in abdominal surgery.

Effect of upper respiratory infection on anaesthesia induced atelectasis in paediatric patients

Upper respiratory tract infection (URI) symptoms are known to increase perioperative respiratory adverse events (PRAEs) in children undergoing general anaesthesia. General anaesthesia per se also induces atelectasis, which may worsen with URIs and yield detrimental outcomes. However, the influence of URI symptoms on anaesthesia-induced atelectasis in children has not been investigated. This study aimed to demonstrate whether current URI symptoms induce aggravation of perioperative atelectasis in children. Overall, 270 children aged 6 months to 6 years undergoing surgery were prospectively recruited. URI severity was scored using a questionnaire and the degree of atelectasis was defined by sonographic findings showing juxtapleural consolidation and B-lines. The correlation between severity of URI and degree of atelectasis was analysed by multiple linear regression. Overall, 256 children were finally analysed. Most children had only one or two mild symptoms of URI, which were not associated with the atelectasis score across the entire cohort. However, PRAE occurrences showed significant correspondence with the URI severity (odds ratio 1.36, 95% confidence interval 1.10–1.67, p = 0.004). In conclusion, mild URI symptoms did not exacerbate anaesthesia-induced atelectasis, though the presence and severity of URI were correlated with PRAEs in children.

Trial registration: Clinicaltrials.gov (NCT03355547).

Lung Ultrasonography in the Monitoring of Intraoperative Recruitment Maneuvers

Introduction: Postoperative respiratory failure is a serious problem in patients who undergo general anesthesia. Approximately 90% of mechanically ventilated patients during the surgery may develop atelectasis that leads to perioperative complications. Aim: The aim of this study is to determine whether it is possible to optimize recruitment maneuvers with the use of chest ultrasonography, thus limiting the risk of respiratory complications in patients who undergo general anesthesia. Methodology: The method of incremental increases in positive end-expiratory pressure (PEEP) values with simultaneous continuous ultrasound assessments was employed in mechanically ventilated patients. Results: The study group comprised 100 patients. The employed method allowed for atelectasis reduction in 91.9% of patients. The PEEP necessary to reverse areas of atelectasis averaged 17cmH₂O, with an average peak pressure of 29cmH₂O. The average PEEP that prevented repeat atelectasis was 9cmH₂O. A significant improvement in lung compliance and saturation was obtained. Conclusions: Ultrasound-guided recruitment maneuvers facilitate the patient-based adjustment of the process. Consequently, the reduction in ventilation pressures necessary to aerate intraoperative atelectasis is possible, with the simultaneous reduction in the risk of procedure-related complications.

Use of lung ultrasound for diagnosis and monitoring of coronavirus disease 2019 pneumonia: A case report

Knowledge of lung ultrasound characteristics of coronavirus disease 2019 pneumonia might be useful for early diagnosis and clinical monitoring of patients, and lung ultrasound can help to control the spread of infection in healthcare settings. In this case report, a 36-year-old man with severe acute respiratory syndrome coronavirus 2 infection was diagnosed by reverse transcription-polymerase chain reaction testing of a nasopharyngeal swab. The lung ultrasound findings for this patient were the interstitial-alveolar damage showing bilateral, diffuse pleural line abnormalities, subpleural consolidations, white lung areas and thick, irregular vertical artifacts. When the patient recovered from the severe acute respiratory syndrome coronavirus 2 infection, lung ultrasound images showed a normal pleural line with A-lines regularly reverberating. Performing lung ultrasound at the bedside minimizes the need to move the patient, thus reducing the risk of spreading infection among healthcare staff. Lung ultrasound is useful for early diagnosis and evaluation of the severity of coronavirus disease 2019 pneumonia and for monitoring its progress over the course of the disease.

Effects of Intraoperative Ventilation Strategy on Perioperative Atelectasis Assessed by Lung Ultrasonography in Patients Undergoing Open Abdominal Surgery: a Prospective Randomized Controlled Study

BACKGROUND

Protective mechanical ventilation using low tidal volume has been introduced to surgical patients to reduce the incidence of postoperative pulmonary complications. We investigated the effects of protective ventilation (PV) techniques on anesthesia-induced atelectasis identified via lung ultrasonography in patients undergoing abdominal surgery.

METHODS

A total of 42 adult patients who were scheduled for open abdominal surgery with an expected duration > 2 hours were included in the study. Patients were randomized to receive either conventional ventilation (CV; tidal volume of 9-10 mL/kg predicted body weight [PBW] with no positive end-expiratory pressure [PEEP]) or PV (tidal volume of 6-8 mL/kg PBW and 5 cmH₂O PEEP) via pressure-controlled ventilation with volume guaranteed. Lung ultrasonography was performed at four predefined time points to assess perioperative atelectasis by dividing each hemithorax into six quadrants based on a modified lung ultrasound (LUS) scoring system.

RESULTS

The tidal volume delivered to patients was 9.65 ± 1.65 mL/kg PBW in the CV group and 6.31 ± 0.62 mL/kg PBW in the PV group. Ventilation using low tidal volume led to similar LUS scores in all lung areas and at all time points compared to ventilation using high tidal volume. There was no significant difference between the groups in the number of patients requiring recruitment maneuvers at the end of surgery.

CONCLUSION

Ventilation with low tidal volume combined with 5 cmH₂O PEEP did not cause further loss of aeration compared to ventilation with high tidal volume. Low tidal volume ventilation can be used in patients without lung injury based on lung assessment by bedside lung ultrasonography.

TRIAL REGISTRATION

Clinical Research Information Service Identifier: KCT0003746.

Feasibility and efficacy of lung ultrasound to investigate pulmonary complications in patients who developed postoperative Hypoxaemia-a prospective study

Background

Postoperative pulmonary complications (PPCs) and hypoxaemia are associated with morbidity and mortality. We aimed to evaluate the feasibility and efficacy of lung ultrasound (LUS) to diagnose PPCs in patients suffering from hypoxaemia after general anaesthesia and compare the results to those of thoracic computed tomography (CT).

Methods

Adult patients who received general anaesthesia and suffered from hypoxaemia in the postanaesthesia care unit (PACU) were analysed. Hypoxaemia was defined as an oxygen saturation measured by pulse oximetry (SPO₂) less than 92% for more than 30 s under ambient air conditions. LUS was performed by two trained anaesthesiologists once hypoxaemia occurred. After LUS examination, each patient was transported to the radiology department for thoracic CT scan within 1 h before returning to the ward.

Results

From January 2019 to May 2019, 113 patients (61 men) undergoing abdominal surgery (45 patients, 39.8%), video-assisted thoracic surgery (31 patients, 27.4%), major orthopaedic surgery (17 patients, 15.0%), neurosurgery (10 patients, 8.8%) or other surgery (10 patients, 8.8%) were included. CT diagnosed 327 of 1356 lung zones as atelectasis, while LUS revealed atelectasis in 311 of the CT-confirmed zones. Pneumothorax was detected by CT scan in 75 quadrants, 72 of which were detected by LUS. Pleural effusion was diagnosed in 144 zones on CT scan, and LUS detected 131 of these zones. LUS was reliable in diagnosing atelectasis (sensitivity 98.0%, specificity 96.7% and diagnostic accuracy 97.2%), pneumothorax (sensitivity 90.0%, specificity 98.9% and diagnostic accuracy 96.7%) and pleural effusion (sensitivity 92.9%, specificity 96.0% and diagnostic accuracy 95.1%).

Conclusions

Lung ultrasound is feasible, efficient and accurate in diagnosing different aetiologies of postoperative hypoxia in healthy-weight patients in the PACU.

Trial registration

Current Controlled Trials NCT03802175, 2018/12/05, www.ClinicalTrials.gov

Lung ultrasonography as a tool to guide perioperative atelectasis treatment bundle in head and neck cancer patients undergoing free flap reconstructive surgeries: a preliminary observational study

Introduction

General anesthesia causes pulmonary atelectasis within few minutes of induction. This can have significant impact on postoperative outcome of cancer patients undergoing prolonged reconstructive surgeries.

Objective

The purpose of this study was to evaluate the impact of sonographically detected perioperative atelectasis on the need for postoperative oxygen supplementation, bronchodilator therapy and assisted chest physiotherapy in patients undergoing free flap surgeries for head and neck carcinoma.

Methods

Twenty eight head and neck cancer patients underwent bilateral pulmonary ultrasonographic assessments before and after lung surgery. Lung ultrasound scores, serum lactate, and PaO₂/FiO₂ ratio were measured both at the beginning and at end of the surgery. Patients were scanned in the supine position and the number of single and confluent B lines was noted. These values were correlated with the need for oxygen therapy, requirement of bronchodilators and total weaning time to predict the postoperative outcome. Other factors affecting weaning were also studied.

Results

Among twenty eight patients, seven had mean lung ultrasound score of ≥10.5 which correlated with prolonged weaning time (144.56 ± 33.5 min vs. 66.7 ± 15.7 min; p = 0.005). The change in lung ultrasound score significantly correlated with change in PaO₂/FiO₂ ratio (r = −0.56, p = 0.03). Elevated total leukocyte count >8200 μL and serum lactate >2.1 mmoL/L also predicted prolonged postoperative mechanical ventilation.

Conclusion

This preliminary study detected significant levels of perioperative atelectasis using point of care lung ultrasonography in head and neck cancer patients undergoing long duration surgical reconstructions. Higher lung ultrasound scores highlighted the need for frequent bronchodilator nebulizations as well as assisted chest physiotherapy and were associated with delayed weaning. We propose more frequent point of care lung ultrasonographic evaluations and use of recruitment maneuvers to reduce the impact of perioperative pulmonary atelectasis.

Lung ultrasound score to determine the effect of fraction inspired oxygen during alveolar recruitment on absorption atelectasis in laparoscopic surgery: a randomized controlled trial

Background

Although the intraoperative alveolar recruitment maneuver (RM) efficiently treats atelectasis, the effect of Fio₂ on atelectasis during RM is uncertain. We hypothesized that a high Fio₂ (1.0) during RM would lead to a higher degree of postoperative atelectasis without benefiting oxygenation when compared to low Fio₂ (0.4).

Methods

In this randomized controlled trial, patients undergoing elective laparoscopic surgery in the Trendelenburg position were allocated to low- (Fio₂ 0.4, n = 44) and high-Fio₂ (Fio₂ 1.0, n = 46) groups. RM was performed 1-min post tracheal intubation and post changes in supine and Trendelenburg positions during surgery. We set the intraoperative Fio₂ at 0.4 for both groups and calculated the modified lung ultrasound score (LUSS) to assess lung aeration after anesthesia induction and at surgery completion. The primary outcome was modified LUSS at the end of the surgery. The secondary outcomes were the intra- and postoperative Pao₂ to Fio₂ ratio and postoperative pulmonary complications.

Results

The modified LUSS before capnoperitoneum and RM (P = 0.747) were similar in both groups. However, the postoperative modified LUSS was significantly lower in the low Fio₂ group (median difference 5.0, 95% CI 3.0–7.0, P < 0.001). Postoperatively, substantial atelectasis was more common in the high-Fio₂ group (relative risk 1.77, 95% CI 1.27–2.47, P < 0.001). Intra- and postoperative Pao₂ to Fio₂ were similar with no postoperative pulmonary complications. Atelectasis occurred more frequently when RM was performed with high than with low Fio₂; oxygenation was not benefitted by a high-Fio_2.

Conclusions

In patients undergoing laparoscopic surgery in the Trendelenburg position, absorption atelectasis occurred more frequently with high rather than low Fio₂. No oxygenation benefit was observed in the high-Fio₂ group.

Trial registration

ClinicalTrials.gov, NCT03943433. Registered 7 May 2019,

Comparison between volume-controlled ventilation and pressure-controlled volume-guaranteed ventilation in postoperative lung atelectasis using lung ultrasound following upper abdominal laparotomies: a prospective randomized study

Background

Atelectasis is a common side effect of general anesthesia. Prevention of lung atelectasis, carbon dioxide retention, and chest infection would improve the quality of medical care and decrease hospital stay and costs. The aim of this study was to compare the effects of volume-controlled ventilation (VCV) and pressure-controlled volume-guaranteed ventilation (PCVG) on postoperative lung atelectasis using lung ultrasound (LUS) following upper abdominal laparotomies.

Results

Sixty patients (male and female) scheduled for upper abdominal laparotomies. They were randomly allocated into two equal groups: Group A (n = 30): received intraoperative volume-controlled ventilation (VCV) mode and group (n = 30): received intraoperative pressure-controlled ventilation volume-guaranteed (PCV-VG) mode. Arterial blood samples were obtained immediately after extubation, and 30, 120, 240, and 360 min postextubation. Lung ultrasound was done intraoperatively at 30 min from induction, immediate, and 120 and after 360 min postoperatively. There was difference between two groups favoring PCV-VG group but that difference failed to be statically significant regarding arterial partial pressure of oxygen (PaO₂) and arterial carbon dioxide tension (PaCo₂) between the two groups in preoperative, immediate postoperative, and 120, 240, and 360 min postoperative. Arterial oxygen saturation (SaO₂) was significantly lower among patients in the VCV group immediate postextubation compared with patients in group PCV-VG (p value = 0.009*). Although signs of atelectasis were low in group B, 36.7% of the patients showed normal lung ultrasound, 63.3% showed various abnormalities, 46.7% showed the presence of lung pulse (vertical rhythmic movement synchronous with cardiac pulsation through motionless lung), and 46.7% showed B lines (vertical lines indicate abnormal lung aeration), while 30% of the patients showed the absence of A-lines (indicates the absence of lung sliding and abnormal lung aeration). Also, some patients demonstrated more than one sign. However, there was no a significant difference between the two groups both showed atelectasis immediate, 2 h and 6 h postoperatively.

Conclusion

PCV-VG offered no significant advantage over VCV regarding the occurrence of the postoperative atelectasis. However, we prefer to use PCV-VG as postoperative hypoxia and atelectasis was much less in that mode. Further, large-scale studies are required to confirm these findings and to establish a definite conclusion.

Perioperative Transthoracic Lung Ultrasound for Assessment of Pulmonary Outcome in Adolescent Idiopathic Scoliosis Patients: Prospective, Observational Pilot Study

The purpose of study was to evaluate the perioperative lung ultrasound findings of patients undergoing scoliosis correction. LUS examination was performed examined three 3 times for each patient: 20 min after starting mechanical ventilation of the lungs(preoperative), after surgery when the patient was placed in the supine position(postoperative), and 20 min after arrival in the post-anaesthesia care unit. Arterial blood gas analyses, mechanical ventilation parameters, peripheral oxygen saturation(SpO2) were also checked. Twenty-six patients completed the study. The changes of LUS score(20 min) was significantly negatively correlated with the partial pressure of arterial oxygen(PaO2)/fraction of inspired oxygen(FiO2) ratio change(P = 0.039, r = −0.40). The change in mean convex side LUS score was significantly greater than that of the concave side as determined by two-factor repeated measures analysis of variance(p = 0.001). Multiple regression analysis revealed perioperative LUS change was the significant factor related to the oxygen index change (p = 0.042). One case of pneumothorax was diagnosed and pleural thickening more than 5 mm was detected in 8 patients and five patients of those were diagnosed pleural effusion and performed thoracentesis after surgery. Postoperative increase of LUS score was related with deteriorating of oxygenation at one day after surgery, and it suggests that lung ultrasound allows prediction of postoperative hypoxia and facilitates the diagnosis of pulmonary complications at operation room in AIS patients.

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 (FI O2 ) can cause direct pulmonary toxicity and pulmonary complications. The purpose of this study was to evaluate the effect of different FI 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) FI O2 group. The low FI O2 group consistently received 30% air-oxygen mixture during preoxygenation, ultrasound-guided recruitment maneuver, and mechanical ventilation. The high FI 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 FI 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

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

The diagnostic accuracy for ARDS of global versus regional lung ultrasound scores - a post hoc analysis of an observational study in invasively ventilated ICU patients

Background

Semi-quantification of lung aeration by ultrasound helps to assess presence and extent of pulmonary pathologies, including the acute respiratory distress syndrome (ARDS). It is uncertain which lung regions add most to the diagnostic accuracy for ARDS of the frequently used global lung ultrasound (LUS) score. We aimed to compare the diagnostic accuracy of the global versus those of regional LUS scores in invasively ventilated intensive care unit patients.

Methods

This was a post-hoc analysis of a single-center observational study in the mixed medical–surgical intensive care unit of a university-affiliated hospital in the Netherlands. Consecutive patients, aged ≥ 18 years, and are expected to receive invasive ventilation for > 24 h underwent a LUS examination within the first 2 days of ventilation. The Berlin Definition was used to diagnose ARDS, and to classify ARDS severity. From the 12-region LUS examinations, the global score (minimum 0 to maximum 36) and 3 regional scores (the ‘anterior,’ ‘lateral,’ and ‘posterior’ score, minimum 0 to maximum 12) were computed. The area under the receiver operating characteristic (AUROC) curve was calculated and the best cutoff for ARDS discrimination was determined for all scores.

Results

The study enrolled 152 patients; 35 patients had ARDS. The global score was higher in patients with ARDS compared to patients without ARDS (median 19 [15–23] vs. 5 [3–9]; P < 0.001). The posterior score was the main contributor to the global score, and was the only score that increased significantly with ARDS severity. However, the posterior score performed worse than the global score in diagnosing ARDS, and it had a positive predictive value of only 50 (41–59)% when using the optimal cutoff. The combined anterolateral score performed as good as the global score (AUROC of 0.91 [0.85–0.97] vs. 0.91 [0.86–0.95]).

Conclusions

While the posterior score increases with ARDS severity, its diagnostic accuracy for ARDS is hampered due to an unfavorable signal-to-noise ratio. An 8-region ‘anterolateral’ score performs as well as the global score and may prove useful to exclude ARDS in invasively ventilated ICU patients.

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.