Intratidal recruitment/derecruitment persists at low and moderate positive end-expiratory pressure in paediatric patients

Lung ultrasound assessment of atelectasis following different anesthesia induction techniques in pediatric patients: a propensity score-matched, observational study

INTRODUCTION

Atelectasis is a well-documented complication in pediatric patients undergoing general anesthesia. Its incidence varies significantly based on surgical procedures and anesthesia techniques. Inhalation induction, commonly used to avoid the discomfort of venipuncture, is suspected to cause higher rates of respiratory complications, including atelectasis, compared to intravenous induction. This study aimed to evaluate the impact of inhalation versus intravenous anesthesia induction on atelectasis formation in pediatric patients, as assessed by lung ultrasound (LUS).

METHODS

This propensity score-matched observational study was conducted at a tertiary pediatric hospital in Milan, Italy. Inclusion criteria were children ≤ 18 years undergoing elective surgery with general anesthesia. Patients were divided into inhalation and intravenous induction groups. LUS was performed before and after anesthesia induction to assess lung aeration. The primary endpoint was the global LUS score post-induction, with secondary endpoints including the incidence and distribution of atelectasis.

RESULTS

Of the 326 patients included, 65% underwent inhalation induction and 35% intravenous induction. The global LUS score was significantly higher in the inhalation group (12.0 vs. 4.0, p < 0.001). After propensity score matching (for age, presence of upper respiratory tract infection, duration of induction, and PEEP levels at induction), average treatment effect (ATE) of mask induction was 5.89 (95% CI, 3.21-8.58; p < 0.001) point on LUS global score and a coefficient of 0.35 (OR 1.41) for atelectasis.

DISCUSSION

Inhalation induction is associated with a higher incidence of atelectasis in pediatric patients also when we adjusted for clinically relevant covariates.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT06069414.

Association of different central venous pressure levels with outcome of living-donor liver transplantation in children under 12 years

BACKGROUND

Pediatric liver transplantation is an important modality for treating biliary atresia. The overall survival (OS) rate of pediatric liver transplantation has significantly improved compared with that of 20 years ago, but it is still unsatisfactory. The anesthesia strategy of maintaining low central venous pressure (CVP) has shown a positive effect on prognosis in adult liver transplantation. However, this relationship remains unclear in pediatric liver transplantation. Thus, this study was conducted to review the data of pediatric living-donor liver transplantation to analyze the associations of different CVP levels with the prognosis of recipients.

METHODS

This was a retrospective study and the patients were divided into two groups according to CVP levels after abdominal closure: low CVP (LCVP) (≤ 10 cmH2O, n = 470) and high CVP (HCVP) (> 10 cmH2O, n = 242). The primary outcome measured in the study was the overall survival rate. The secondary outcomes included the duration of mechanical ventilation in the intensive care unit (ICU), length of stay in the ICU, and postoperative stay in the hospital. Patient demographic and perioperative data were collected and compared between the two groups. Kaplan-Meier curves were constructed to determine the associations of different CVP levels with the survival rate.

RESULTS

In the study, 712 patients, including 470 in the LCVP group and 242 in the HCVP group, were enrolled. After propensity score matching, 212 pairs remained in the group. The LCVP group showed a higher overall survival rate than the HCVP group in the Kaplan-Meier curves and multivariate Cox regression analyses (P = 0.018), and the HCVP group had a hazard ratio of 2.445 (95% confidence interval, 1.163-5.140).

CONCLUSION

This study confirmed that a low-CVP level at the end of surgery is associated with improved overall survival and a shorter length of hospital stay.

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.

Understanding pediatric ventilation in the operative setting. Part II: Setting perioperative ventilation

Approaches toward lung-protective ventilation have increasingly been investigated in recent years. Despite evidence being found in adults undergoing surgery, data in younger children are still scarce and controversial. From a physiological perspective, however, the continuously changing characteristics of the respiratory system from birth through adolescence require an approach based on the analysis of each individual patient. The modern anesthesia workstation provides such information, with the technical strengths and weaknesses being discussed in a review preceding the present work (see Part I). The present summary aims to provide ideas on how to translate the information displayed on the anesthesia workstation to patient-oriented clinical ventilation settings.

Determining optimal positive end-expiratory pressure and tidal volume in children by intratidal compliance: a prospective observational study

BACKGROUND

Limited data exist regarding optimal intraoperative ventilation strategies for the paediatric population. This study aimed to determine the optimal combination of PEEP and tidal volume (V_T) based on intratidal compliance profiles in healthy young children undergoing general anaesthesia.

METHODS

During anaesthesia, infants (1 month-1 yr), toddlers (1-3 yr), and children (3-6 yr) were assigned serially to four ventilator settings: PEEP 8 cm H₂O/V_T 8 ml kg^-1 (PEEP8/V_T8), PEEP 10 cm H₂O/V_T 5 ml kg^-1 (PEEP10/V_T5), PEEP 10 cm H₂O/V_T 8 ml kg^-1 (PEEP10/V_T8), and PEEP 12 cm H₂O/V_T 5 ml kg^-1 (PEEP12/V_T5). The primary outcome was intratidal compliance profile, classified at each ventilator setting as horizontal (indicative of optimal alveolar ventilatory conditions), increasing, decreasing, or combinations of increasing/decreasing/horizontal compliance. Secondary outcomes were peak inspiratory, plateau, and driving pressures.

RESULTS

Intratidal compliance was measured in 15 infants, 13 toddlers, and 15 children (15/43 [35%] females). A horizontal compliance profile was most frequently observed with PEEP10/V_T5 (60.5%), compared with PEEP10/V_T8, PEEP8/V_T8, and PEEP12/V_T5 (23.3-34.9%; P<0.001). Decreasing compliance profiles were most frequent when V_T increased to 8 ml kg^-1, PEEP increased to 12 cm H₂O, or both. Plateau airway pressures were lower at PEEP8/V_T8 (16.9 cm H₂O [2.2]) and PEEP10/V_T5 (16.7 cm H₂O [1.7]), compared with PEEP10/V_T8 (19.5 cm H₂O [2.1]) and PEEP12/V_T5 (19.0 cm H₂O [2.0]; P<0.001). Driving pressure was lowest with PEEP10/V_T5 (4.6 cm H₂O), compared with other combinations (7.0 cm H₂O [2.0]-9.5 cm H₂O [2.1]; P<0.001).

CONCLUSIONS

V_T 5 ml kg^-1 combined with 10 cm H₂O PEEP may reduce atelectasis and overdistension, and minimise driving pressure in the majority of mechanically ventilated children <6 yr. The effect of these PEEP and V_T settings on postoperative pulmonary complications in children undergoing surgery requires further study.

CLINICAL TRIAL REGISTRATION

NCT04633720.

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.

Ultrashort inspiratory times homogenize ventilation distribution in an inhomogeneous two-compartment model of the neonatal lung

BACKGROUND

Inhomogeneous lung ventilation and pulmonary air leaks are common adverse effects of mechanical ventilation in preterm infants suffering from respiratory distress syndrome. We hypothesized that shortening of inspiratory times can improve the homogeneity of lung aeration. We assumed that ultrashort inspiratory times lead to a full build-up of pressure in regions with low compliance while maintaining incomplete filling of regions with high compliance.

METHODS

We connected a two-compartment model of the lung with different compliances of the two compartments to a neonatal ventilator. Pressures and flow rates were measured separately for each compartment at inspiratory times ranging from 0.1 to 0.8 s and various combinations of tidal volumes.

RESULTS

An inspiratory time of 0.8 s resulted in near total pressure equalization between the airway pressure and the two compartments, as 97% of the maximum applied peak pressure was reached in the low compliance compartment and 95% in the high compliance compartment. The distribution of the tidal volume was proportional to the compartment compliance. Ultrashort inspiratory times lowered the peak pressure and tidal volume in the high compliance compartment but maintained higher pressure and volume in the low compliance compartment. An inspiratory time of 0.2 s resulted in a peak pressure of 80% of peak airway pressure in the low compliance compartment and in 61% of peak airway pressure in the high compliance compartment (p < .001).

CONCLUSION

Ventilation with ultrashort inspiratory times may improve homogeneity of air distribution in inhomogeneous lungs of ventilated preterm or term infants.

Evaluation of Different Positive End-Expiratory Pressures Using Supreme™ Airway Laryngeal Mask during Minor Surgical Procedures in Children

Background and objectives: The laryngeal mask is the method of choice for airway management in children during minor surgical procedures. There is a paucity of data regarding optimal management of mechanical ventilation in these patients. The Supreme™ airway laryngeal mask offers the option to insert a gastric tube to empty the stomach contents of air and/or gastric juice. The aim of this investigation was to evaluate the impact of positive end-expiratory positive pressure (PEEP) levels on ventilation parameters and gastric air insufflation during general anesthesia in children using pressure-controlled ventilation with laryngeal mask. Materials and Methods: An observational trial was carried out in 67 children aged between 1 and 11 years. PEEP levels of 0, 3 and 5 mbar were tested for 5 min in each patient during surgery and compared with ventilation parameters (dynamic compliance (mL/cmH₂O), etCO₂ (mmHg), peak pressure (mbar), tidal volume (mL), respiratory rate (per minute), FiO₂ and gastric air (mL)) were measured at each PEEP. Air was aspirated from the stomach at the start of the sequence of measurements and at the end. Results: Significant differences were observed for the ventilation parameters: dynamic compliance (PEEP 5 vs. PEEP 3: p < 0.0001, PEEP 5 vs. PEEP 0: p < 0.0001, PEEP 3 vs. PEEP 0: p < 0.0001), peak pressure (PEEP 5 vs. PEEP 3: p < 0.0001, PEEP 5 vs. PEEP 0: p < 0.0001, PEEP 3 vs. PEEP 0: p < 0.0001) and tidal volume (PEEP 5 vs. PEEP 3: p = 0.0048, PEEP 5 vs. PEEP 0: p < 0.0001, PEEP 3 vs. PEEP 0: p < 0.0001). All parameters increased significantly with higher PEEP, with the exception of etCO₂ (significant decrease) and respiratory rate (no significant difference). We also showed different values for air quantity in the comparisons between the different PEEP levels (PEEP 5: 2.8 ± 3.9 mL, PEEP 3: 1.8 ± 3.0 mL; PEEP 0: 1.6 ± 2.3 mL) with significant differences between PEEP 5 and PEEP 3 (p = 0.0269) and PEEP 5 and PEEP 0 (p = 0.0209). Conclusions: Our data suggest that ventilation with a PEEP of 5 mbar might be more lung protective in children using the Supreme™ airway laryngeal mask, although gastric air insufflation increased with higher PEEP. We recommend the use of a laryngeal mask with the option of inserting a gastric tube to evacuate potential gastric air.

Dependency of respiratory system mechanics on positive end-expiratory pressure and recruitment maneuvers in lung healthy pediatric patients-A randomized crossover study

BACKGROUND

The lungs of pediatric patients are subjected to tidal derecruitment during mechanical ventilation and in contrast to adult patients this unfavorable condition cannot be resolved with small c increases. This raises the question if higher end-expiratory pressure increases or recruitment maneuvers may resolve tidal derecruitment in pediatric patients.

AIMS

We hypothesized that higher PEEP resolves tidal derecruitment in pediatric patients and that recruitment maneuvers between the pressure changes support the improvement of respiratory system mechanics.

METHODS

The effects of end-expiratory pressure changes from 3 to 7 cmH₂ O and vice versa without and with intermediate recruitment maneuvers on respiratory system mechanics and regional ventilation were investigated in 57 mechanically ventilated pediatric patients. The intratidal respiratory system compliance was determined from volume and pressure data before and after PEEP changes and categorized to indicate tidal derecruitment.

RESULTS

Tidal derecruitment occurred comparably frequently at PEEP 3 cmH₂ O without (13 out of 14 cases) and with recruitment maneuver (14 out of 14 cases) and at PEEP 7 cmH₂ O without (13 out of 14 cases) and with recruitment maneuver (13 out of 15 cases).

CONCLUSIONS

We conclude that contrary to our hypothesis, PEEP up to 7 cmH₂ O is not sufficient to resolve tidal derecruitment and that recruitment maneuvers may be dispensable in mechanically ventilated pediatric patients.

Post-extubation continuous positive airway pressure improves oxygenation after pediatric laparoscopic surgery: A randomized controlled trial

BACKGROUND

Effects of intraoperative recruitment maneuvers (RMs) on oxygenation and pulmonary compliance are lost during recovery if high inspired oxygen and airway suctioning are used. We investigated the effect of post-extubation noninvasive CPAP mask application on the alveolar arterial oxygen difference [(A-a) DO₂ ] after pediatric laparoscopic surgery.

METHODS

Sixty patients (1-6 years) were randomly allocated to three groups of 20 patients, to receive zero end-expiratory pressure (ZEEP group), RM with decremental PEEP titration only (RM group), or followed with post-extubation CPAP for 5 minutes (RM-CPAP group). Primary outcome was [(A-a) DO₂ ] at 1 hour postoperatively. Secondary outcomes were respiratory mechanics, arterial blood gas analysis, hemodynamics, and adverse events.

RESULTS

At 1 hour postoperatively, mean [(A-a) DO₂ ] (mm Hg) was lower in the RM-CPAP group (41.5 ± 13.2, [95% CI 37.6-45.8]) compared to (80.2 ± 13.7 [72.6-87.5], P < 0.0001] and (59.2 ± 14.6, [54.8-62.6], P < 0.001) in the ZEEP and RM groups. The mean PaO₂ (mm Hg) at 1 hour postoperatively was higher in the RM-CPAP group (156.2 ± 18.3 [95% CI 147.6-164.7]) compared with the ZEEP (95.9 ± 15.9 [88.5-103.3], P < 0.0001) and RM groups (129.1 ± 15.9 [121.6-136.5], P < 0.0001). At 12 hours postoperatively, mean [(A-a) DO₂ ] and PaO₂ were (9.6 ± 2.1 [8.4-10.8]) and (91.9 ± 9.4 [87.5-96.3]) in the RM-CPAP group compared to (25.8 ± 5.5 [23.6-27.6]) and (69.9 ± 5.5 [67.4-72.5], P < 0.0001) in the ZEEP group and (34.3 ± 13.2, [28.4-40.2], P < 0.0001) and (74.03 ± 9.8 [69.5-78.6], P < 0.0001) in the RM group. No significant differences of perioperative adverse effects were found between groups.

CONCLUSIONS

An RM done after pneumoperitoneum inflation followed by decremental PEEP titration improved oxygenation at 1 hour postoperatively. The addition of an early post-extubation noninvasive CPAP mask ventilation improved oxygenation at 12 hours postoperatively.

Positive end-expiratory pressure improves elastic working pressure in anesthetized children

Background

Positive end-expiratory pressure (PEEP) has been demonstrated to decrease ventilator-induced lung injury in patients under mechanical ventilation (MV) for acute respiratory failure. Recently, some studies have proposed some beneficial effects of PEEP in ventilated patients without lung injury. The influence of PEEP on respiratory mechanics in children is not well known. Our aim was to determine the effects on respiratory mechanics of setting PEEP at 5 cmH₂O in anesthetized healthy children.

Methods

Patients younger than 15 years old without history of lung injury scheduled for elective surgery gave informed consent and were enrolled in the study. After usual care for general anesthesia, patients were placed on volume controlled MV. Two sets of respiratory mechanics studies were performed using inspiratory and expiratory breath hold, with PEEP 0 and 5 cmH₂O. The maximum inspiratory and expiratory flow (Q_I and Q_E) as well as peak inspiratory pressure (PIP), plateau pressure (P_PL) and total PEEP (tPEEP) were measured. Respiratory system compliance (C_RS), inspiratory and expiratory resistances (RawI and RawE) and time constants (K_TI and K_TE) were calculated. Data were expressed as median and interquartile range (IQR). Wilcoxon sign test and Spearman’s analysis were used. Significance was set at P < 0.05.

Results

We included 30 patients, median age 39 (15–61.3) months old, 60% male. When PEEP increased, PIP increased from 12 (11,14) to 15.5 (14,18), and C_RS increased from 0.9 (0.9,1.2) to 1.2 (0.9,1.4) mL·kg^− 1·cmH₂O^− 1; additionally, when PEEP increased, driving pressure decreased from 6.8 (5.9,8.1) to 5.8 (4.7,7.1) cmH₂O, and Q_E decreased from 13.8 (11.8,18.7) to 11.7 (9.1,13.5) L·min^− 1 (all P < 0.01). There were no significant changes in resistance and Q_I.

Conclusions

Analysis of respiratory mechanics in anesthetized healthy children shows that PEEP at 5 cmH₂O places the respiratory system in a better position in the P/V curve. A better understanding of lung mechanics may lead to changes in the traditional ventilatory approach, limiting injury associated with MV.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0611-8) contains supplementary material, which is available to authorized users.