Hyperbaric oxygen treatment and nephrotoxicity induced by gentamicin in rats

Effects of Hyperbaric Oxygen Therapy on Hemogram, Serum Biochemistry and Coagulation Parameters of Dogs Undergoing Elective Laparoscopic-Assisted Ovariohysterectomy

BACKGROUND

This study explored the effects of hyperbaric oxygen therapy (HBOT) on hemogram, serum biochemistry and hemostatic variables in female dogs undergoing laparoscopic-assisted ovariohysterectomy (OVH).

MATERIALS

Thirty adult, mixed-breed, healthy female dogs were randomly divided into the following three groups: HBOT + SURG (exposed to two absolute atmospheres (ATAs) for 45 min followed by laparoscopic-assisted OVH), HBOT (exposed to two ATAs for 45 min) and SURG (laparoscopic-assisted OVH). Blood samples were collected at T0 (at the admission), at T1, 24 h after T0 (immediately after HBOT in the HBOT + SURG and HBOT groups, and immediately before anesthetic premedication in the SURG group), and at T2, 48 h after T0 (24 h after HBOT and anesthetic premedication).

METHODS

Assessments included erythrogram, leukogram, thrombogram, renal and hepatic serum biochemistry, prothrombin time (PT), activated partial thromboplastin time (APTT), buccal mucosal bleeding time (BMBT) and bloodstain area (BA) on hygroscopic paper collected at the BMBT.

RESULTS

Both the HBOT + SURG and SURG groups presented neutrophilia (p ≤ 0.0039) at T2 and an increase of ALP at T2 (p ≤ 0.0493), the SURG group presented an increase in leukocyte count at T2 (p = 0.0238) and the HBOT + SURG group presented a reduction in lymphocyte count at T2 (p = 0.0115). In the HBOT + SURG group, there was a reduction in PT and APTT in relation to the baseline value (p ≤ 0.0412).

CONCLUSIONS

A session of HBOT at two ATAs for 45 min did not cause changes in the BMBT or BA in healthy female dogs. Some blood parameters investigated (neutrophil and lymphocyte count, ALP, PT and APTT) were affected by the use of HBOT.

Renal Effects of Hyperbaric Oxygen Therapy in Patients with Diabetes Mellitus: A Retrospective Study

Hyperbaric oxygen therapy (HBOT) is an adjunctive treatment for patients with diabetic foot ulcers. The prolonged high oxygen level used in HBOT can produce oxidative stress, which may be harmful to the kidney. Animal experiments suggest HBOT does not harm renal function and may have an antiproteinuric effect, but little is known on the effect of HBOT in humans. We performed a retrospective chart review of 94 patients with diabetes mellitus who underwent HBOT at our institution over an eight-year period. Thirty-two patients had serum creatinine levels within 60 days of the start and the end of treatment. Creatinine levels were 1.41 ± 0.89 mg/dl before and 1.52 ± 1.17 mg/dl after hyperbaric treatments with no statistically significant difference (mean (postcreatinine + precreatinine/2) = 0.10 mg/dl, SE = 0.11, t = 0.89). Twenty-three patients had proteinuria measurements before and after HBOT mainly by urine dipstick analysis. A Wilcoxon signed-rank test showed less proteinuria after HBOT than before (N = 23, p=0.002). Proteinuria was absent in 7 of 23 patients (30%) before HBOT and 13 of 23 patients (57%) after HBOT, a reduction by almost 50%. This observation is remarkable because oxidative stress might be expected to increase rather than decrease proteinuria.

Role of Hypoxia in Renal Failure Caused by Nephrotoxins and Hypertonic Solutions

Hypoxia plays a role in the pathogenesis of acute kidney injury under diverse clinical settings, including nephrotoxicity. Although some nephrotoxins exert direct renal parenchymal injury, likely with consequent altered oxygenation, others primarily reduce renal parenchymal oxygenation, leading to hypoxic tubular damage. As outlined in this review, nephrotoxin-related renal hypoxia may result from an altered renal oxygen supply (cyclosporine), enhanced oxygen consumption for tubular transport (agents inducing osmotic diuresis), or their combination (nonsteroidal anti-inflammatory drugs, radiocontrast agents, and others). Most agents causing hypoxic renal injury further supress physiologic low medullary Po₂, in which a limited regional blood supply barely matches the intense regional tubular transport and oxygen consumption. The medullary tubular transport and blood supply are finely matched, securing oxygen sufficiency. Predisposition to hypoxia-mediated nephrotoxicity by medical conditions, such as chronic kidney disease or diabetes, may be explained by malfunctioning of control systems that normally maintain medullary oxygenation. However, this propensity may be diminished by hypoxia-mediated adaptive responses governed by hypoxia-inducible factors. Recent reports have suggested that inhibitors of sodium-glucose cotransporters and the administration of hypertonic saline may be added to the growing list of common therapeutic interventions that intensify medullary hypoxia, and potentially could lead to hypoxic acute kidney injury.