The Inflammatory Response to Pediatric Cardiac Surgery: Correlation of Granulocyte Adhesion Molecule Expression with Postoperative Oxygenation

Surgical Repair of Mitral Valve Disease in Children: Perioperative Changes in Respiratory Function

OBJECTIVE

To assess the profile of changes in airway and respiratory tissue mechanics within a follow-up study performed in children with mitral valve disease, before and after surgical valve repair.

DESIGN

Perioperative measurements in a prospective, consecutive cross-sectional study.

SETTING

University hospital, tertiary care teaching hospital

PARTICIPANTS

The study comprised 24 children with congenital or post-rheumatic mitral valve insufficiency.

INTERVENTIONS

Input impedance of the respiratory system during spontaneous breathing was measured before and 5 days and 3 weeks after mitral valve surgery. In addition, airway and respiratory tissue mechanics and pulmonary arterial pressure were assessed with the patient under general anesthesia preoperatively and immediately postoperatively. Respiratory tissue elastance and changes in airway measurements were estimated from forced oscillatory impedance data by fitting an appropriate model.

MEASUREMENT AND MAIN RESULTS

Relating airway and respiratory tissue mechanics to previously established reference values obtained in age-matched healthy control patients revealed abnormal respiratory function (135±6.2% and 148±13% in respiratory elastance and resistance, respectively; p<0.001). Improvement in the airway properties was observed immediately after surgery (-15.2±3.4%; p<0.005) and lasted for the study period (-19±4.1%; p<0.001). Respiratory tissue elastance, which correlated preoperatively to the diastolic pulmonary arterial pressure, decreased only 5 days postoperatively (-20.6±4.1%; p<0.005). However, there was no evidence of a clear, immediate effect of surgery on the tissue mechanical parameters measured intraoperatively despite a decrease in diastolic pulmonary pressure.

CONCLUSIONS

Mitral valve disease in children leads to abnormal airway and respiratory tissue mechanics. Even though surgical repair of mitral insufficiency alleviates abnormal airway function, residual lung tissue stiffening may persist even weeks after the surgery, contributing to a sustained impairment in lung function.

Leucocyte filtration of residual heart-lung machine blood in children undergoing congenital heart surgery

Cardiopulmonary bypass (CPB) leads to a generalized inflammatory reaction, resulting in increased postoperative leucocyte counts and decreased pulmonary function. In adults, removal of leucocytes from the residual heart - lung machine blood after CPB improved postoperative oxygenation. In children, however, the clinical effects of leucocyte filtration of the residual heart - lung machine blood are unknown. Therefore, we measured postoperative leucocyte counts and arterial blood oxygenation in children undergoing congenital cardiac surgery in a randomized prospective study. Anaesthesia and CPB were standardized. After CPB, the residual heart-lung machine blood was collected as usual. In a group of 25 children, this blood was filtered with a leucocyte depletion filter before transfusion. A control group of 25 children received this blood unfiltered. We found that the postoperative leucocyte counts were significantly lower in the filter group than in the control group ( p=0.02, repeated measurements ANOVA). This difference reached a maximum on the second postoperative day (12.9×109/L filter versus 15.9×109/L control, p=0.02, Student’s t-test). Values for the arterial blood oxygenation on the first postoperative day were not different between the two groups (15.5±1 kPa filter versus 14.6±1.3 kPa control, p=0.57, Student’s t-test). We conclude that leucocyte filtration of the residual heart-lung machine blood reduced systemic leucocyte counts, but did not improve arterial blood oxygenation in children after congenital heart surgery.

Effect of modified ultrafiltration on the inflammatory response in paediatric open-heart surgery: a prospective, randomized study

Modified ultrafiltration (MUF) is often used in conjunction with paediatric cardiac surgery with cardiopulmonary bypass (CPB) and is thought to improve clinical outcome. It is unclear whether these improvements (if any) are due to the removal of inflammatory mediators. In this prospective study, 18 children aged 12-24 months undergoing uncomplicated cardiac surgery with methylprednisolone added in the pump prime were randomized to receive CPB with ( n= 10) and without ( n= 8) MUF. Cytokines (TNFα, IL-6, IL- 1β, IL-10, IL-1ra), complement split products (C3d, C4d) and coagulation system activation (F1+ 2, ATIII) were measured pre-, peri- and up to 48 h postoperatively. For clinical outcome, the alveolar-arterial oxygen (A-a) gradient, transfusion requirement, drain loss, mean blood pressure and requirement for inotropic support were registered up to 24 h postoperatively. Our results show an improvement in postoperative oxygenation as well as a tendency towards decreased drain loss and improved haemodynamics in the MUF group. There were no intergroup differences detectable for TNFα, IL-1β, IL-1ra, complement and coagulation markers. We conclude that MUF in itself does not significantly influence TNFα, IL-1β, IL-1ra and the complement and coagulation profiles in children undergoing cardiac surgerywith CPB. Despite this, there was some evidence for improved clinical outcome. Our results do not support that MUF improves postoperative organ function by modulation of the measured markers of inflammation.

Pulmonary functions before and after pediatric cardiac surgery

This study aimed to assess pulmonary functions before and after cardiac surgery in infants with congenital heart diseases and pulmonary overflow and to clarify which echocardiographic parameter correlates best with lung mechanics. Between 2008 and 2009, 30 infants with left-to-right shunt congenital acyanotic heart diseases who had indications for reparative surgery of these lesions were assessed by echocardiography and infant pulmonary function tests before the operation and 6 months afterward. Tests using baby body plethysmography were performed to assess the following infant pulmonary functions: tidal volume, respiratory rate, respiratory system compliance (C(rs)) and respiratory system resistance, functional residual capacity (FRC), and airway resistance. The mean age of the patients was 10.47 ± 3.38 months, and their mean weight was 6.81 ± 1.67 kg. Ventricular septal defect and combined lesions were the predominant cardiac diseases (26.7%). Comparison of the infant pulmonary function tests showed a highly significant improvement in all the parameters between the preoperative and 6-month postoperative visits (p < 0.0001). Systolic pulmonary artery pressure had a statistically significant negative correlation with C(rs) (r = -0.493, p = 0.006) and a positive correlation with FRC (r = 0.450, p = 0.013). The findings showed that C(rs) had a statistically significant negative correlation with the pulmonary artery size (r = -0.398, p = 0.029) and the left atrium size (r = -0.395, p = 0.031), whereas the pulmonary artery size had a statistically positive correlation with effective resistance (r = 0.416, p = 0.022) and specific effective resistance (r = 0.604, p = 0.0001). Surgical correction of left-to-right shunt congenital heart diseases had a positive impact on lung compliance, airway resistance, and FRC. Noninvasive echocardiographic parameters assessing pulmonary vascular engorgement and pulmonary artery pressure were closely related to these infant pulmonary function test indexes.

Xenon anesthesia reduces TNFα and IL10 in bariatric patients

BACKGROUND

Anesthesia is able to modulate the balance between proinflammatory and anti-inflammatory cytokine production during surgery. The aim of this study is to assess the effect of three anesthesia approaches, total intravenous anesthesia (TIVA), inhalation anesthesia, and xenon anesthesia, on sieric levels of nitric oxide (NO), IL6, IL10, and TNFα in obese patients undergoing Roux-en-Y laparoscopic gastric bypass.

METHODS

Thirty adult morbidly obese patients (BMI > 35) scheduled for Roux-en-Y laparoscopic gastric bypass were randomly recruited and allocated to TIVA (N = 10), inhalation anesthesia (SEV, N = 10), and xenon anesthesia (XE, N = 10). Exclusion criteria were ASA IV, age <18 or >60 years, and Mallampati IV. Opioid dosage and ventilation parameters were standardized. Sieric levels of NO, IL6, IL10, and TNFα were assessed at T0 (before induction of anesthesia), T1 (end of surgery), and T2 (12 h after the end of surgery). We compared the relative cytokine level variations (delta) at T1 and T2 and the cytokine exposure levels calculated as the area under the curve (AUC) between T0 and T2 in the XE and non-XE (SEV + TIVA) groups.

RESULTS

At T1, we found a significant ΔIL10 (reduction) and ΔTNFα (reduction) between XE and SEV (p < 0.05) and XE and TIVA (p < 0.05) groups. At T2, ΔIL10 was still significant. Furthermore, we found a reduced AUC value for TNFα in the XE group.

CONCLUSIONS

Xenon anesthesia seems able to inhibit postoperative proinflammatory cytokine imbalance in morbidly obese patients undergoing Roux-en-Y laparoscopic gastric bypass; the reduced ΔTNFα at T1 and the reduced global exposition to TNFα in the XE group may explain the reduced ΔIL10 at T1 and T2.

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.

Effects of Ketamine on Serum and Tracheobronchial Aspirate Interleukin-6 Levels in Infants Undergoing Cardiac Surgery

OBJECTIVE

Corrective surgery for congenital heart defects in children frequently requires cardiopulmonary bypass (CPB). Serum and bronchoalveolar levels of interleukin-6 (IL-6) may be useful in assessing the severity of the systemic inflammatory response after CPB. In the present study, the authors aimed to compare the effects of ketamine anesthesia and isoflurane anesthesia with respect to serum and tracheobronchial aspirate (TBA) IL-6 levels in infants undergoing CPB for cardiac surgery.

DESIGN

Prospective and randomized controlled study.

SETTING

University-based teaching hospital.

PARTICIPANTS

Thirty-four infants aged 2 to 24 months were randomized into 2 groups.

INTERVENTIONS

In group K (n = 17), anesthesia was induced with intravenous (IV) ketamine, 1 to 2 mg/kg, and fentanyl, 1 to 2 microg/kg, and was maintained with infusions of ketamine, 25 to 75 microg/kg/min, and fentanyl, 10 microg/kg/h. In group I (n = 17), induction was achieved with IV thiopental sodium, 3 to 5 mg/kg, and fentanyl, 1 to 2 microg/kg, and was maintained with 1% isoflurane and fentanyl, 10 mug/kg/h. Blood and TBA samples were obtained at 6 and 4 stages, respectively.

MEASUREMENTS AND MAIN RESULTS

Serum IL-6 and TBA IL-6 levels were similar in the 2 groups at all stages (p > 0.05).

CONCLUSION

The present results show that ketamine anesthesia does not provide superiority over isoflurane anesthesia with respect to serum and TBA IL-6 levels.

Changes in respiratory mechanics among infants undergoing heart surgery

Children with excessive pulmonary blood flow (PBF) from congenital heart disease have abnormal respiratory mechanics. Exposure to hypothermic cardiopulmonary bypass (CPB) adversely affects lung function. We designed this study of 106 patients to determine the changes in respiratory mechanics in infants younger than 1 yr undergoing heart surgery. Dynamic respiratory compliance (Cdyn) and total respiratory resistance (Rrs) were measured before surgical incision, after sternal closure in the operating room, and after arrival in the intensive care unit. The following data were recorded: age, weight, preoperative pulmonary infiltrates, preoperative mechanical ventilation, evidence of increased PBF before surgery, duration of CPB, duration of aortic cross-clamp, duration of deep hypothermic circulatory arrest, use of steroids, and volume of ultrafiltrate removed. Repeated-measures analysis of variance with covariate analysis was used to determine the effect of each covariate on Cdyn and Rrs at the three time periods. Rrs improved after cardiac surgery correcting increases in PBF, and this was most pronounced in neonates. Among infants with normal or reduced PBF, cardiac surgery with CPB led to a reduction in Cdyn. We consider that the benefits of surgical correction of pulmonary overcirculation outweigh the negative effects of CPB on respiratory mechanics.

IMPLICATIONS

The benefits of surgical correction of pulmonary overcirculation outweigh the negative effects of cardiopulmonary bypass on respiratory mechanics in infants.

Neutrophils and platelets accumulate in the heart, lungs, and kidneys after cardiopulmonary bypass in neonatal pigs

OBJECTIVE

Cardiac surgery with cardiopulmonary bypass elicits a systemic inflammatory response. An exaggerated response is associated with organ dysfunction and increased morbidity and mortality.

DESIGN

The aim of the present study was to investigate whether the cardiopulmonary bypass procedure in itself results in accumulation of isotope-labeled platelets, polymorphonuclear neutrophils, and fibrinogen at organ levels in neonatal pigs and to monitor changes in organ function.

SETTING

Pediatric cardiopulmonary bypass setup with 60 mins of aortic cross-clamp time and 120 mins of hypothermic cardiopulmonary bypass time.

SUBJECTS

Thirty piglets were allocated to sternotomy alone (sham group, n = 15) or to sternotomy and cardiopulmonary bypass (n = 15).

MEASUREMENTS AND MAIN RESULTS

Isotope-labeled autologous polymorphonuclear neutrophils, platelets, and commercially available fibrinogen were infused, and the specific accumulation at organ level was measured in a gamma counter 4 hrs after termination of cardiopulmonary bypass. Concomitant changes in oxygenation index and cardiac output were registered. Animals exposed to cardiopulmonary bypass showed a significantly higher technetium-99m-polymorphonuclear neutrophil accumulation in the lungs and kidneys, whereas indium-111-platelets accumulated in the heart and kidneys compared with the sham group. There was a significantly larger increase in oxygenation index and significantly larger decrease in cardiac output between the pre- and postcardiopulmonary bypass period in the cardiopulmonary bypass group compared with the sham group.

CONCLUSIONS

The cardiopulmonary bypass procedure without cardiac surgery elicits organ dysfunction in terms of impaired respiratory and hemodynamic function. Platelets and polymorphonuclear neutrophils were entrapped in the heart, lungs, and kidneys of cardiopulmonary bypass animals, indicating that cell accumulation may contribute to the developing organ dysfunction.

The systemic inflammatory response after cardiac surgery with cardiopulmonary bypass in children

Paediatric cardiac surgery often requires cardiopulmonary bypass (CPB) during the surgical intervention. CPB is known to elicit a systemic inflammatory response with activation of the complement and coagulation systems, stimulation of cytokine production, cellular entrapment in organs, neutrophil activation with degranulation, platelet activation, and endothelial dysfunction. These changes are associated with a risk of postoperative organ dysfunction and increased morbidity and mortality in the postoperative period. Clinical studies have concentrated on measurement of inflammatory markers and mediators in peripheral blood, where the systemic inflammatory response in the paediatric cardiac patient seems to be different from the adult case. Looking at the organ level, experimental studies have the advantage of providing information contributing to a better understanding of the pathological events that may lead to the deteriorated organ function. This review focuses on the systemic inflammatory response after cardiac surgery with CPB in children and experimental CPB models.