Pulmonary complaints and lung function after pediatric kidney transplantation

Bronchiectasis in children following kidney transplantation in New Zealand

AIM

Bronchiectasis is an acquired chronic respiratory condition with a relatively high incidence in New Zealand children. Bronchiectasis following kidney transplant has been reported internationally. This study aimed to identify the incidence rate of bronchiectasis following paediatric kidney transplantation. Secondary aims were to assess the impact on kidney allograft function and identify risk factors that might prompt earlier diagnosis.

METHODS

Case control study of children who developed bronchiectasis following kidney transplant in New Zealand. All children who were transplanted during the 16-year period from 2001 to 2016 were included. Each identified case was matched with two controls (children who did not develop bronchiectasis and received a kidney transplant within the closest time period to their matched case). Data were collected on baseline demographics, clinical variables, immunosuppression and allograft function.

RESULTS

Of 95 children who had a kidney transplant during the specified time period, eight (8.4%) developed bronchiectasis at a median of 4 years post-transplant. The mean incidence rate of bronchiectasis was 526 cases per 100 000 paediatric kidney transplant population per year. The majority of children were Māori or Pasifika ethnicity and lived in areas of greater socio-economic deprivation. Immunosuppression burden and allograft function were not significantly different between groups.

CONCLUSIONS

The incidence rate of bronchiectasis following paediatric kidney transplantation is substantially higher than the baseline paediatric incidence rate in New Zealand. A high index of suspicion for bronchiectasis and prompt investigation of children post kidney transplantation with a history of recurrent lower respiratory tract infection or chronic cough are advised.

Home-based inspiratory muscle training in pediatric patients after kidney transplantation: a randomized clinical trial

BACKGROUND

Chronic kidney disease (CKD) represents the irreversible stages of renal failure and is a growing worldwide public health issue associated with increases in morbidity, mortality, and decreased quality of life. Kidney transplantation is considered one of the best treatment options in this population. However, even after surgery, respiratory muscle strength is below normal values, and inspiratory muscle training (IMT) improves respiratory muscle function, strength, and endurance. This study aimed to evaluate the effects of IMT regarding respiratory muscle strength, functional capacity, and pulmonary function in pediatric kidney transplant recipients with CKD, and secondarily, to assess the biochemical profile of patients after intervention.

METHODS

This is a randomized, double-blind, placebo-controlled trial. Patients were randomized into two groups, intervention (IG) and control (CG) and performed IMT home-based training for 6 weeks. In the IG, the load was adjusted to 40% of the maximal inspiratory pressure and in the CG was adjusted to a minimum placebo load (9 cm H₂O).

RESULTS

Thirty-one patients were randomly allocated to the intervention (n = 16) or control (n = 15) groups. There were no differences at baseline between groups. Increase of 35% in the maximal inspiratory pressure predicted and 26% in the maximal expiratory pressure predicted in the IG were found, compared with 5 and 4% in the CG. There was an increase in hemoglobin and hematocrit values in the IG.

CONCLUSIONS

Home-based IMT provides a significant increase in respiratory muscle strength, without changes in functional capacity and pulmonary function. Benefits regarding biochemical markers (hemoglobin and hematocrit) were also observed.

A pilot study to examine the effect of chronic treatment with immunosuppressive drugs on mucociliary clearance in a vagotomized murine model

BACKGROUND

Previously, we have demonstrated that mucociliary clearance (MCC) is diminished within the first months after surgery in lung transplant patients and the explanation for the reduction in MCC is unknown. We hypothesized that chronic treatment with a commonly prescribed regimen of immunosuppressive drugs significantly impairs MCC. We tested this hypothesis in a murine model of lung transplantation.

METHODS

Fifteen C57BL/6 mice underwent vagotomy on the right side to simulate denervation associated with lung transplantation in humans. For 6 days, seven mice (controls) were intraperitoneally injected with three 100 µL doses of phosphate buffered saline and eight mice (immunosuppressed) were injected with three 100 µL injections of tacrolimus (1 mg/kg), mycophenolate mofetil (30 mg/kg), and prednisone (2 mg/kg) once daily. Then, mice inhaled the radioisotope (99m)technetium and underwent gamma camera imaging of their lungs for 6.5 hrs. Counts in the right lung at 1-1.5 hrs and at 6-6.5 hrs were first background-corrected and then decay-corrected to time 0 counts. Decay-corrected counts were then divided by time 0 counts. Retention at each time point was subtracted from 1.00 and multiplied by 100% to obtain percent removed by mucociliary clearance.

RESULTS

Although there was a slowing of MCC at 1-1.5 hrs for the immunosuppressed mice, there was no statistical difference in MCC measured at 1-1.5 hrs for the two groups of mice. At 6-6.5 hrs, MCC was significantly slower in the immunosuppressed mice, compared to controls, with 7.78±5.9% cleared versus 23.01±11.7% cleared, respectively (p = 0.006).

CONCLUSIONS

These preliminary results suggest that chronic treatment with immunosuppressive medications significantly slows MCC in vagotomized C57BL/6 mice. These findings could shed light on why MCC is reduced in lung transplant patients whose lungs are denervated during surgery and who are chronically treated with immunosuppressive drugs post surgery.