Effect of cardiopulmonary bypass and aortic clamping on functional residual capacity and ventilation distribution in children

Use of high-flow nasal cannula versus other noninvasive ventilation techniques or conventional oxygen therapy for respiratory support following pediatric cardiac surgery: A systematic review and meta-analysis

INTRODUCTION

Noninvasive respiratory support may be provided to decrease the risk of postextubation failure following surgery. Despite these efforts, approximately 3%-27% of infants and children still experience respiratory failure after tracheal extubation following cardiac surgery. This systematic review evaluates studies comparing the efficacy of high-flow nasal cannula to conventional oxygen therapy such as nasal cannula and other noninvasive ventilation techniques in preventing postextubation failure in this patient population.

METHODS

A systematic and comprehensive search was conducted in major databases including MEDLINE, EMBASE, Web of Science, and Central. The search encompassed articles focusing on the prophylactic use of high-flow nasal cannula following tracheal extubation in pediatric patients undergoing cardiac surgery for congenital heart disease. The inclusion criteria for this review consisted of randomized clinical trials as well as observational, cohort, and case-control studies.

RESULTS

A total of 1295 studies were screened and 12 studies met the inclusion criteria. These 12 studies included a total of 1565 children, classified into three groups: seven studies compared high-flow nasal cannula to noninvasive ventilation techniques, four studies compared high-flow nasal cannula to conventional oxygen therapy, and one observational single-arm study explored the use of high-flow nasal cannula with no control group. There was no significant difference in the incidence of tracheal reintubation between high-flow nasal cannula and conventional oxygen therapy (risk ratio [RR] = 0.67, 95% confidence interval [CI]: 0.24-1.90, p = .46). However, there was a lower incidence of tracheal reintubation in patients who were extubated to high-flow nasal cannula versus those extubated to noninvasive ventilation techniques (RR = 0.45, 95% CI: 0.32-0.63, p < .01). The high-flow nasal cannula group also demonstrated a lower mortality rate compared to the noninvasive ventilation techniques group (RR = 0.31, 95% CI: 0.16-0.61, p < .01) as well as a shorter postoperative length of stay (mean difference = -8.76 days, 95% CI: -13.08 to -4.45, p < .01) and shorter intensive care length of stay (mean difference = -4.63 days, 95% CI: -9.16 to -0.11, p = .04).

CONCLUSION

High-flow nasal cannula is more effective in reducing the rate of postextubation failure compared to other forms of noninvasive ventilation techniques following surgery for congenital heart disease in pediatric-aged patients. high-flow nasal cannula is also associated with lower mortality rates and shorter length of stay. However, when comparing high-flow nasal cannula to conventional oxygen therapy, the findings were inconclusive primarily due to a limited number of scientific studies available on this specific comparison. Future study is needed to further define the benefit of high-flow nasal cannula compared to conventional oxygen therapy and various types of noninvasive ventilation techniques.

Noninvasive respiratory support preventing reintubation after pediatric cardiac surgery-A systematic review

OBJECTIVE

To analyze the optimal postextubation respiratory support in pediatric cardiac surgery patients.

DESIGN

Systematic review of randomized controlled trials.

SETTING

Pediatric or neonatal intensive care units.

PARTICIPANTS

All aged children (<16 years) having cardiac surgery and postoperative invasive ventilation.

INTERVENTION

Noninvasive respiratory support, including high flow nasal cannula (HFNC), conventional oxygen therapy (COT), noninvasive positive pressure ventilation (NIPPV), continuous positive pressure (CPAP), and noninvasive high-frequency oscillatory ventilation (NHFOV).

MEASUREMENT AND MAIN RESULTS

Studies were not pooled for statistical synthesis due to the limited number and quality of the included studies. Risk ratios with 95% confidence intervals were calculated for individual studies. A total of 167 studies were screened and six were included. The risk of bias was low in one, high in one, and had some concerns in four of the studies. Extubation failure (defined as reintubation) was the main outcome of interest. Risk ratio for reintubation was 0.10 (CI 0.02-0.40) and 1.07 (CI 0.16-7.26) in HFNC versus COT, 0.49 (CI 0.05-5.28) in HFNC versus NIPPV, 0.40 (CI 0.08-1.94) in HFNOV versus CPAP, 0.75 (CI 0.26-2.18) in HFNOV versus NIPPV, and 1.37 (CI 0.33-5.73) in CPAP versus NIPPV. Treatment durations did not differ between the groups.

CONCLUSION

We did not find clear evidence of a difference in reintubation rates and other clinical outcomes between different noninvasive ventilation strategies. Evidence certainty was assessed to be very low due to the risk of bias, the small number of included studies, and high imprecision. Future quality studies are needed to determine the optimal postextubation support in pediatric cardiac surgery patients.

Comparison of high-flow nasal cannula oxygenation and non-invasive ventilation for postoperative pediatric cardiac surgery: a meta-analysis

OBJECTIVE

To evaluate the efficacy of high-flow nasal cannula oxygenation (HFNC) versus non-invasive ventilation (NIV) in pediatric patients post-congenital heart surgery (CHS) through a meta-analysis.

METHODS

A comprehensive literature search was conducted across the Chinese biomedical literature database, Vip database, CNKI, Wanfang, PubMed, Embase, Cochrane Library, and Web of Science until December 20, 2022. We selected RCTs or cohort studies that met inclusion criteria for a meta-analysis using RevMan 5.4 software.

RESULTS

Our search yielded five publications, comprised of one randomized controlled trial and four cohort studies. Meta-analysis revealed a significant reduction in reintubation rates in children post-CHS treated with HFNC as compared to NIV [RR = 0.36, 95%CI(0.25 ~ 0.53), P < 0.00001]. There was also a notable reduction in the duration of ICU stay [MD = -4.75, 95%CI (-9.38 ~ -0.12), P = 0.04]. No statistically significant differences were observed between HFNC and NIV in terms of duration of mechanical ventilation, 24 h PaO2, and PaCO2 post-treatment (P > 0.05). Furthermore, both groups showed no significant difference in the duration of extracorporeal circulation [MD = -8.27, 95%CI(-17.16 ~ 0.62), P = 0.07].

CONCLUSIONS

For pediatric patients post-CHS, HFNC appears to be more effective than NIV in reducing reintubation rates and shortening the CICU stay.

Comparative evaluation of high-flow nasal cannula oxygenation vs nasal intermittent ventilation in postoperative paediatric patients operated for acyanotic congenital cardiac defects

Background

This study aimed to compare high-flow nasal cannula (HFNC) oxygenation vs nasal intermittent ventilation (NIV) oxygenation for respiratory care after extubation in postoperative paediatric cardiac patients.

Methods

This study was a randomised controlled trial. One hundred twenty-one paediatric patients with acyanotic congenital heart disease undergoing corrective cardiac surgery on cardiopulmonary bypass were included in the study. Patients were randomised to receive either HFNC (AIRVO) or NIV (RAM Cannula) postextubation. Arterial blood gas was analysed at different time points perioperatively.

Results

Patients in both the groups were matched with respect to diagnosis and demographic profiles. Baseline hemodynamic and respiratory parameters were also similar in both the groups. Patients in HFNC/AIRVO group did not show improved carbon dioxide (CO2) washout but showed improved pO2 and pO2/FiO2 ratio immediate postextubation. Reintubation rate and other intensive care unit (ICU) complications were similar in both the groups.

Conclusion

Postcardiopulmonary bypass respiratory complications in paediatric patients with congenital acyanotic heart disease can be minimised with newer oxygen therapy devices such as AIRVO (HFNC) or RAM cannula (NIV). In comparison between these two, AIRVO did not show improved CO2 washout over RAM cannula; however, it did provide better oxygenation as measured by pO2 in arterial blood and pO2/FiO2 ratio immediate postextubation. Also, long-term results such as duration of mechanical ventilation and ICU stay were not affected by the choice of device.

Carbon dioxide monitoring in children-A narrative review of physiology, value, and pitfalls in clinical practice

Continuous capnography has been recognised as an essential monitoring device in all anesthetized patients, despite which airway device is in use, regardless of their location, as a measure to improve patient safety. Capnography is the non-invasive measurement of a sample of the exhaled carbon dioxide which has multiple clinical uses including as a method to confirm placement of a tracheal tube and/or to assess ventilation, perfusion and metabolism. Notably, capnography is used during routine paediatric anesthesia to assess ventilation and as a surrogate measure for arterial carbon dioxide pressure. The inaccuracies associated with these surrogate measures need to be considered to inform improved ventilation management of infants and children. This review highlights some major principles to understand the carbon dioxide elimination, the physiology of paediatric capnography, the clinical application and the limitations of capnography during anesthesia for neonates, infants and small children.

End-expiratory lung volume assessment using helium and carbon dioxide in an experimental model of pediatric capnoperitoneum

BACKGROUND

Capnoperitoneum during laparoscopy leads to cranial shift of the diaphragm, loss in lung volume, and risk of impaired gas exchange. Infants are susceptible to these changes and bedside assessment of lung volume during laparoscopy might assist with optimizing the ventilation. Thus, the primary aim was to investigate the monitoring value of a continuous end-expiratory lung volume (EELV) assessment method based on CO₂ dynamics ( EELV CO 2 ) in a pediatric capnoperitoneum model by evaluating the correlation and trending ability against helium washout (EELV_He ).

METHODS

Intra-abdominal pressure (IAP) was randomly varied between 0, 6, and 12 mm Hg with CO₂ insufflation, while positive end-expiratory pressure (PEEP) levels of 3, 6, and 9 cm H₂ O were randomly applied in eight anesthetized and mechanically ventilated chinchilla rabbits. Concomitant EELV CO 2 and EELV_He and lung clearance index (LCI) were obtained under each experimental condition.

RESULTS

Significant correlations were found between EELV CO 2 and EELV_He before capnoperitoneum (r = .85, P < .001), although increased IAP distorted this relationship. The negative influence of IAP was counteracted by the application of PEEP 9, which restored the correlation between EELV CO 2 and EELV_He and resulted in 100% concordance rate between the methods regarding changes in lung volume. EELV_He and LCI showed a curvilinear relationship, and an EELV_He of approximately 20 mL kg^-1 , determined with a receiver operating characteristic curve, was associated with near-normal LCI values.

CONCLUSION

In this animal model of pediatric capnoperitoneum, reliable assessment of changes in EELV based on EELV CO 2 requires an open lung strategy, defined as EELV above approximately 20 mL kg^-1 .

Cardiopulmonary bypass does not induce lung dysfunction after pulmonary thrombarterectomy: role of pulmonary compliance

OBJECTIVES

Pulmonary endarterectomy is a heavy surgical procedure that is performed under cardiopulmonary bypass (CPB) and aimed to cure postembolic pulmonary hypertension. Reperfusion oedema is both the hallmark of successful surgical procedure and the most frequent postoperative complication. Post-CPB lung dysfunction was not mentioned in any report. We undertook a study to determine whether post-CPB lung dysfunction was present in these patients.

METHODS

In a retrospective cohort study with matching on some baseline covariates, we selected 41 patients who had undergone pulmonary endarterectomy and in whom pre-, intra- and postoperative records were complete. The control group was composed of 39 patients operated on from elective cardiac surgery during the same period and matched with a study group for age, gender, body mass index, blood creatinine, diabetes and baseline partial pressure of oxygen/fraction of inspired oxygen ratio. Criteria for post-CPB lung dysfunction were partial pressure of oxygen/fraction of inspired oxygen ratio decrease and bilateral basal oedema. Explanatory variables for post-CPB lung dysfunction were coronary arterial bypass, pleura opening, static pulmonary compliance measured at the time of thorax closed then retracted, fluid infusion, transfusion and vasopressors.

RESULTS

All patients operated on from pulmonary endarterectomy presented radiological oedema reperfusion in surgical unblocking areas. Among them, only 2 had bilateral basal oedema when compared to the 24 patients from the control group (P < 0.001). Partial pressure of oxygen/fraction of inspired oxygen ratio increased in the study group and decreased in the control group (30 ± 109 vs -67 ± 134 mmHg, P < 0.001). Control group patients with high-baseline pulmonary compliance were at risk for post-CPB lung dysfunction.

CONCLUSIONS

Patients operated on from pulmonary endarterectomy were saved from post-CPB lung dysfunction. The latter could be induced by a mechanical phenomenon.

High-flow nasal cannula oxygen therapy vs conventional oxygen therapy in cardiac surgical patients: A meta-analysis

INTRODUCTION

The use of high-flow nasal cannula (HFNC) for the treatment of many diseases has gained increasing popularity. In the present meta-analysis, we aimed to assess the efficacy and safety of HFNCs compared with conventional oxygen therapy (COT) in adult postextubation cardiac surgical patients.

METHOD

We reviewed the Embase, PubMed, Cochrane Central Register of Controlled Trials, Wanfang databases, and the China National Knowledge Infrastructure. Two investigators independently collected the data and assessed the quality of each study. RevMan 5.3 was used for the present meta-analysis.

RESULTS

We included 495 adult postextubation cardiac surgical patients. There was no significant heterogeneity among the studies. Compared with COT, HFNCs were associated with a significant reduction in the escalation of respiratory support (risk ratio, 0.61; 95% confidence interval [CI], 0.46-0.82; z = 3.32, P < .001). There were no significant differences in the reintubation rate (risk ratio, 0.96; 95% CI, 0.04-24.84; z = 0.02, P = .98) or length of intensive care unit stay (weighted mean difference, 0.13; 95% CI, -0.88 to 7.92; z = 1.57, P = .12) between the 2 groups. No severe complications were reported in either group.

CONCLUSIONS

The HFNC could reduce the need for escalation of respiratory support compared with COT, and it could be safely administered in adult postextubation cardiac surgical patients.

Pain and cardiorespiratory responses of children during physiotherapy after heart surgery

OBJECTIVE

The aim of the present study was to determine the occurrence of pain and changes in blood pressure, heart rate, respiratory rate, and arterial oxygen saturation associated with physiotherapy in children undergoing cardiac surgery.

METHODS

Eighteen extubated children were assessed for the presence of pain using the face, legs, activity, cry, consolability scale, and blood pressure, heart rate, respiratory rate and arterial oxygen saturation were simultaneously recorded. The physiological parameters were measured at the following time periods: immediately before physiotherapy, five and 10 minutes after the beginning of physiotherapy, and five minutes after its end. Pain was assessed immediately before physiotherapy, ten minutes after the beginning of physiotherapy and five minutes after its end. Pain and physiological changes were assessed by the Friedman test and the correlation between the physiological parameters and the pain scores was assessed by the Spearman test.

RESULTS

Pain increased during physiotherapy and decreased significantly after it compared to pre-physiotherapy scores. Systolic blood pressure and heart rate increased significantly after 10 minutes of the beginning of physiotherapy. Arterial oxygen saturation tended to decrease during physiotherapy and to increase after it, although without significance. The correlation between pain scores and the physiological variables was significant only for systolic blood pressure and heart rate ten minutes after the beginning of physiotherapy.

CONCLUSION

Manipulation after the beginning of physiotherapy seems to be accompanied by significant pain and by important associated cardiovascular changes. Apparent analgesia and improved respiratory function were observed after respiratory physiotherapy.

Lung volume assessments in normal and surfactant depleted lungs: agreement between bedside techniques and CT imaging

Background

Bedside assessment of lung volume in clinical practice is crucial to adapt ventilation strategy. We compared bedside measures of lung volume by helium multiple-breath washout technique (EELV_MBW,He) and effective lung volume based on capnodynamics (ELV) to those assessed from spiral chest CT scans (EELV_CT) under different PEEP levels in control and surfactant-depleted lungs.

Methods

Lung volume was assessed in anaesthetized mechanically ventilated rabbits successively by measuring i) ELV by analyzing CO₂ elimination traces during the application of periods of 5 consecutive alterations in inspiratory/expiratory ratio (1:2 to 1.5:1), ii) measuring EELV_MBW,He by using helium as a tracer gas, and iii) EELV_CT from CT scan images by computing the normalized lung density. All measurements were performed at PEEP of 0, 3 and 9 cmH₂O in random order under control condition and following surfactant depletion by whole lung lavage.

Results

Variables obtained with all techniques followed sensitively the lung volume changes with PEEP. Excellent correlation and close agreement was observed between EELV_MBW,He and EELV_CT (r = 0.93, p < 0.0001). ELV overestimated EELV_MBW,He and EELV_CT in normal lungs, whereas this difference was not evidenced following surfactant depletion. These findings resulted in somewhat diminished but still significant correlations between ELV and EELV_CT (r = 0.58, p < 0.001) or EELV_MBW,He (0.76, p < 0.001) and moderate agreements.

Conclusions

Lung volume assessed with bedside techniques allow the monitoring of the changes in the lung aeration with PEEP both in normal lungs and in a model of acute lung injury. Under stable pulmonary haemodynamic condition, ELV allows continuous lung volume monitoring, whereas EELV_MBW,He offers a more accurate estimation, but intermittently.

Abnormal Lung Function in Adults With Congenital Heart Disease: Prevalence, Relation to Cardiac Anatomy, and Association With Survival

Background—

Restrictive lung defects are associated with higher mortality in patients with acquired chronic heart failure. We investigated the prevalence of abnormal lung function, its relation to severity of underlying cardiac defect, its surgical history, and its impact on outcome across the spectrum of adult congenital heart disease.

Methods and Results—

A total of 1188 patients with adult congenital heart disease (age, 33.1±13.1 years) undergoing lung function testing between 2000 and 2009 were included. Patients were classified according to the severity of lung dysfunction based on predicted values of forced vital capacity. Lung function was normal in 53% of patients with adult congenital heart disease, mildly impaired in 17%, and moderately to severely impaired in the remainder (30%). Moderate to severe impairment of lung function related to complexity of underlying cardiac defect, enlarged cardiothoracic ratio, previous thoracotomy/ies, body mass index, scoliosis, and diaphragm palsy. Over a median follow-up period of 6.7 years, 106 patients died. Moderate to severe impairment of lung function was an independent predictor of survival in this cohort. Patients with reduced force vital capacity of at least moderate severity had a 1.6-fold increased risk of death compared with patients with normal lung function ( P =0.04).

Conclusions—

A reduced forced vital capacity is prevalent in patients with adult congenital heart disease; its severity relates to the complexity of the underlying heart defect, surgical history, and scoliosis. Moderate to severe impairment of lung function is an independent predictor of mortality in contemporary patients with adult congenital heart disease.

Perfil das crianças submetidas à correção de cardiopatia congênita e análise das complicações respiratórias

OBJETIVO: Descrever as características demográficas e clínicas de crianças submetidas à cirurgia de correção de cardiopatia congênita (CC) em um hospital universitário, comparando pacientes com e sem complicações respiratórias no pós-operatório. MÉTODOS: Estudo retrospectivo, realizado por meio de consulta de prontuários de crianças submetidas à cirurgia corretiva de CC em hospital universitário brasileiro no período de novembro de 2006 a setembro de 2007. Foram analisados dados relativos a idade, sexo, peso, comorbidades e tipo de CC das crianças incluídas no estudo, comparando pacientes com e sem complicações respiratórias no pós-operatório. Foram utilizados o teste de Mann-Whitney e exato de Fisher, considerando-se significante p<0,05. RESULTADOS: Foram analisados 55 (95%) prontuários disponíveis de crianças submetidas à cirurgia cardíaca com mediana de idade de 37,5 meses, sendo 49% meninos. Presença de três ou mais CC foi verificada em 29,1% dos pacientes e 53% dos casos apresentavam comorbidades. Quanto às complicações respiratórias no pós-operatório, 31% dos pacientes evoluíram com atelectasia/derrame pleural e 5,5% laringite/pneumomediastino/lesão pulmonar. Complicações em outros sistemas foram identificadas em 24% dos pacientes. A sobrevida foi de 89% e crianças com complicações respiratórias no pós-operatório foram submetidas a maior tempo de ventilação mecânica e permanência hospitalar (p<0,001). CONCLUSÕES: O conhecimento da relação entre complicações respiratórias e maior tempo de ventilação mecânica e hospitalização reforça a necessidade de prevenir tais complicações para redução dos custos hospitalares.

Longitudinal evaluation the pulmonary function of the pre and postoperative periods in the coronary artery bypass graft surgery of patients treated with a physiotherapy protocol

Background

The treatment of coronary artery disease (CAD) seeks to reduce or prevent its complications and decrease morbidity and mortality. For certain subgroups of patients, coronary artery bypass graft surgery (CABG) may accomplish these goals. The objective of this study was to assess the pulmonary function in the CABG postoperative period of patients treated with a physiotherapy protocol.

Methods

Forty-two volunteers with an average age of 63 ± 2 years were included and separated into three groups: healthy volunteers (n = 09), patients with CAD (n = 9) and patients who underwent CABG (n = 20). Patients from the CABG group received preoperative and postoperative evaluations on days 3, 6, 15 and 30. Patients from the CAD group had evaluations on days 1 and 30 of the study, and the healthy volunteers were evaluated on day 1. Pulmonary function was evaluated by measuring forced vital capacity (FVC), maximum expiratory pressure (MEP) and Maximum inspiratory pressure (MIP).

Results

After CABG, there was a significant decrease in pulmonary function (p < 0.05), which was the worst on postoperative day 3 and returned to the preoperative baseline on postoperative day 30.

Conclusion

Pulmonary function decreased after CABG. Pulmonary function was the worst on postoperative day 3 and began to improve on postoperative day 15. Pulmonary function returned to the preoperative baseline on postoperative day 30.

Changes in lung volume during spells in children with Tetralogy of Fallot under general anesthesia

OBJECTIVE

To describe the changes in end-expiratory lung volume and ventilation inhomogeneities during spells in three children with Tetralogy of Fallot.

DESIGN

After approval of the institutional Ethics Committee was obtained, children were included in a study protocol that included the assessment of end-expiratory lung volume and ventilation inhomogeneity, using a sulfur hexafluoride multibreath washout technique at different times before and during the surgical repair of congenital heart disease. Additional parental consent was sought to publish this subseries.

SETTING

Operation theater in a tertiary-care university hospital.

PATIENTS

We report the changes in end-expiratory lung volume and ventilation inhomogeneity in three children undergoing Tetralogy of Fallot repair who spelled before surgical incision. While starting the immediate treatment with phenylephrine and increasing Fio2 to 1.0, we were able to measure respiratory function. During the spell, end-expiratory lung volume decreased and ventilation inhomogeneities increased significantly and only recovered slowly even after return of Sao2 to prespell values.

CONCLUSIONS

These data show the deleterious effect of a spell on respiratory function, which may worsen hypoxemia. The loss in lung volume can have a deleterious additive effect in the presence of a spell, particularly because of the slow improvement after treatment.

Measurement of end-expiratory lung volume in intubated children without interruption of mechanical ventilation

Purpose

Monitoring end-expiratory lung volume (EELV) is a valuable tool to optimize respiratory settings that could be of particular importance in mechanically ventilated pediatric patients. We evaluated the feasibility and precision of an intensive care unit (ICU) ventilator with an in-built nitrogen washout/washin technique in mechanically ventilated pediatric patients.

Methods

Duplicate EELV measurements were performed in 30 patients between 5 kg and 43 kg after cardiac surgery (age, median + range: 26, 3–141 months). All measurements were taken during pressure-controlled ventilation at 0 cm H₂O of positive end-expiratory pressure (PEEP).

Results

Linear regression between duplicate measurements was excellent (R² = 0.99). Also, there was good agreement between duplicate measurements, bias ± SD: −0.3% (−1.5 mL) ± 5.9% (19.2 mL). Mean EELV ± SD was 19.6 ± 5.1 mL/kg at 0 cm H₂O PEEP. EELV correlated with age (p < 0.001, r = 0.92, R² = 0.78), body weight (p < 0.001, r = 0.91, R² = 0.82) and height (p < 0.001, r = 0.94, R² = 0.75).

Conclusion

This ICU ventilator with an in-built nitrogen washout/washin EELV technique can measure EELV with precision, and can easily be used for mechanically ventilated pediatric patients.