Respiratory Complications

Introduction

Compromised respiratory function has been reported in patients undergoing peritoneal dialysis (PD (1–5). This article will discuss respiratory complications associated with peritoneal dialysis.

Change in Pulmonary Gas Exchange

Studies have shown that peritoneal dialysis can affect pulmonary gas exchange properties. In a trial by O’Brien et al., infusing 2L of peritoneal dialysis fluid (PDF) altered respiratory function in peritoneal dialysis patients. During the study, 2L of PDF was infused in 10 continuous ambulatory peritoneal dialysis (CAPD) patients. Each patient’s forced expiratory volume in 1 second (FEV1), vital capacity (VC), total lung capacity (TLC), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), functional residual capacity (FRC), and airway resistance (Raw) were measured immediately after PDF infusion and 30 minutes after draining the PDF. Additional measurement included oxygen exchange (A-aO2) and partial oxygen (PaO2) and partial carbon dioxide (PCO2) before dialysis and 30 minutes after infusion. The results of the study showed significant reduction in VC (3.99±0.3 vs. 3.81±0.3; p< 0.05), TLC (5.89±0.3 vs. 6.33±0.2; p< 0.05), and FRC (3.56±0.2 vs. 3.78±0.2; p< 0.05) indicating compromised pulmonary gas exchange function. Furthermore, significant reduction in PaO2 (11.03±0.3 vs. 11.35±0.3; p< 0.001) and significant increase in A-aO2 (1.80±0.1 vs. 1.29±0.1; p< 0.001) were observed indicating relative hypoxia. All other measurements remained similar throughout the study. These results show that peritoneal dialysate infusion can reduce respiratory function without affecting airway resistance (6). Although significant results were shown, there are limitations to the study. First, patients were only tested in sitting position; therefore, whether or not the position of patient affects the outcomes cannot be determined. Next, included patients had comorbidities that could reduce pulmonary functions such as chronic obstructive pulmonary disease (COPD; n=1), chronic heart failure (CHF; n=2), hypertension treated with beta-blockers (n=2), and anemia (n=10); however the effects of these confounders were not assessed in the study. Finally, the study had small sample size with only 10 patients.

Although changes in lung volumes are reported with peritoneal dialysis, these reductions are not found to be any more severe than patients with obstructive lung disease. Moreover, in a study by Singh et al., lung volumes in CAPD patients with concurrent COPD normalized within 2 weeks of initiating CAPD suggesting that the body may adapt to the change after a certain period of time, suggesting that obstructive airway disease should not be considered as contraindication to peritoneal dialysis (7).

Volume of dialysate may also contribute to alteration in pulmonary gas exchange associated with peritoneal dialysis. Earlier studies have reported greater reduction in VC with higher dialysate volume (40% with 2L vs. 10% in 1L). Furthermore, greater decrease in PaO2 from baseline with 2L exchanges compared to 1L exchanges was also reported (8).

Increased Abdominal Pressure

The normal intra-abdominal pressure of an empty peritoneal cavity may range from 0.5-2.2 cm H2O. This may increase to 2-10 cm H2O with dialysate infusion(9). There is a concern of increased risk of pulmonary complication such as hydrothorax in peritoneal dialysis patients due to elevated intra-abdominal pressure. Hydrothorax is estimated to occur less 5% of peritoneal dialysis patients; however, one study reported incidence to be as high as 10% (7). It is most commonly observed in chronic patients. However, autopsy reports have shown abnormalities in hemidiaphragms which may lead to hydrothorax in the early stages of peritoneal dialysis. Patients with larger effusions from hydrothorax may present with shortness of breath and dyspnea, which can be confused with fluid-overload symptoms. Using hypertonic solution in these patients to increase ultrafiltration will only further increase intra-abdominal pressure and lead to worsening of the symptoms. These patients may appear to have ultrafiltration failure; however, their peritoneal equilibration test (PET) results are within the normal range. Therefore, proper and thorough diagnosis is important (10).

Position of the patient may also impact the intra-abdominal pressure. According to Twardowski et al., intra-abdominal pressure increases the least in supine position compared to other positions. Thus, in patients who are unable to tolerate peritoneal dialysis due to increased abdominal pressure, supine position may be considered(11).

Ventilation Abnormality

In addition to respiratory complications related to the physical presence of PDF in the peritoneal cavity, other problems have been reported due to increased carbohydrate and lactate loading from dialysate glucose. Increased carbohydrate in peritoneal dialysis solution has been associated with hyperventilation, indicated by increased ventilated volume per minute (VV), O2 consumption per minute (VO2) and CO2 excretion per minute (VCO2) when compared to healthy subjects.  In addition, increased ratios between of ventilated volume and O2 ­consumption or CO2 excretion also indicate hyperventilation n peritoneal dialysis patients. Notably, these patients may present with normal blood pH despite the hyperventilation. Authors have suggested that such phenomena might indicate increased metabolic activities such as via the Kreb cycle, which can increase CO2 production and O­2 consumption without significantly affecting the blood pH (8,10). Acute respiratory acidosis can develop if one retains excessive CO2. Cohn et al. reported a case of a patient who experienced acute respiratory acidosis with when dialysate glucose concentration was increased from 1.5 g to 4.25 g, and subsequent resolution of symptoms with decrease in dialysate glucose concentration.  Although the authors considered other causes of acidosis such as sepsis, none of these symptoms coincided with acidosis. Therefore, the case concludes that increased dialysate concentration is likely the main cause of acidosis (12).

Other – Sleep Apnea

Sleep apnea is another respiratory related complication in peritoneal dialysis. Uncontrolled sleep apnea can cause other complications such as pulmonary arterial and systematic hypertension due to arterial hypoxemia and hypercapnia. The exact cause or the main contributor of sleep apnea in peritoneal dialysis patients is unknown. It is unclear whether or not the presence of dialysate of increased abdominal pressure poses extra sleep disturbances in these patients. In regards to management, it’s been shown that careful management of fluid status in patients can improve sleep apnea (7).

Conclusion

Peritoneal dialysis patients may suffer from various respiratory complications. Because many of these complications may not have clear pathology, it is prudent to monitor these patients and make adjustments as needed.

References

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  2. Epstein SW, Inouye T, Robson M, Oreopoulos DG. Effects of Peritoneal Dialysis Fluid On Ventilation Function. Perit Dial Int. 1982;2(3):120-122.
  3. Gómez-Fernández P, Sánchez Agudo L, Calatrava JM, Escuin F, Selgas R, Martínez ME, Montero A, Sánchez-Sicilia L. Respiratory muscle weakness in uremic patients under continuous ambulatory peritoneal dialysis. Nephron. 1984;36(4):219-223. Available from: http://www.ncbi.nlm.nih.gov/pubmed/6709114.
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  8. Fabris A, Biasioli S, Chiaramonte C, Feriani M, Pisani E, Ronco C, Cantarella G, La Greca G. Buffer metabolism in continuous ambulatory peritoneal dialysis (CAPD): relationship with respiratory dynamics. Trans Am Soc Artif Intern Organs. 1982;28:270-275. Available from: http://www.ncbi.nlm.nih.gov/pubmed/6819670.
  9. Dunsmore S, Bargman JM. Peritoneal dialysis: non-infectious complications. In: Turner N, Lameire N, D G, Winearls CG, Himmelfarb J, Remuzzi G, eds. Oxford Textbook of Clinical Nephrology. Oxford University Press; 2015.
  10. Eiser AR. Pulmonary gas exchange during hemodialysis and peritoneal dialysis: interaction between respiration and metabolism. Am J Kidney Dis. 1985;6(3):131-142. Available from: http://www.ncbi.nlm.nih.gov/pubmed/3929598.
  11. Twardowski ZJ, Khanna R, Nolph KD, Scalamogna A, Metzler MH, Schneider TW, Prowant BF, Ryan LP. Intraabdominal pressures during natural activities in patients treated with continuous ambulatory peritoneal dialysis. Nephron. 1986;44(2):129-135. Available from: http://www.ncbi.nlm.nih.gov/pubmed/3774076.
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P/N 102507-01 Rev A 06/2016