Resistivity and pulsatility indexes in feline kidney disease: a systematic review

Doppler ultrasonography is used in the evaluation of hemodynamics, and the resistivity (RI) and pulsatility (PI) indexes provide information about resistance to blood flow within a vessel. This systematic review was carried out to evaluate renal RI and PI in clinically healthy and nonsedated cats and as well as their usefulness in the evaluation of kidney disease in cats. An electronic search in the PubMed, Scopus, and Web of Science databases was carried out using the terms "resistive index" or "resistivity index" or "pulsatility index;" "Doppler;" "renal" or "kidney;" and "cat" or "feline" in titles, abstracts, and keywords. Variables of interest related to experimental model features, research methods, and technical resources were extracted from the studies. The methodological quality was assessed with SYRCLE's risk of bias tool. Thus, 14 studies involving healthy and sick cats were selected. Interestingly, the upper limits estimated for both RI and PI varied among studies. The upper limits of renal RI for healthy cats varied between 0.64 and 0.72, while for PI, the values varied from 1.06 to 1.29. A limited number of studies evaluated cats with kidney disease. In most studies, RI values of kidneys with different conditions were significantly different from kidneys of healthy animals, indicating that RI values increase with kidney disease. The parameters body weight, heart rate, and age seem to influence the RI values. Standardized studies regarding its realization and description are still necessary to define normal values and analyze its applicability in the clinical diagnostic routine.

Evaluation of a microvascular anastomotic coupler for end-to-side arterial and venous anastomosis for feline renal transplantation

OBJECTIVE

To describe the technique and determine the feasibility of an end-to-side (ETS) anastomosis of the renal vein to vena cava and renal artery to aorta using a microvascular anastomotic coupler (MAC) for feline renal transplantation.

STUDY DESIGN

In vivo experimental study.

ANIMALS

Six purpose-bred domestic shorthair cats.

METHODS

The left kidney was autotransplanted using a MAC for ETS vascular anastomosis. Outcomes included intraoperative hemorrhage from the anastomosis sites, duration of anastomoses, surgical complications, postoperative renal perfusion (including resistive index (RI)) measured by Doppler ultrasonography and computed tomography angiography, and histopathological examination of the left kidney and anastomosis sites (30 days).

RESULTS

Anastomosis was successful in all cats, and intraoperative hemorrhage was negligible. Intraoperative renal perfusion was considered excellent. Venous and arterial anastomoses were completed in 11 minutes 20 seconds (range, 6:38-13:27) and 21 minutes 50 seconds (range, 11:05-30:24), respectively. Vascular occlusion time was 32 minutes (17:43-42:03). One cat was euthanized 5 hours postoperatively because of bleeding from a muscular arterial branch of the dorsal aorta causing hemoabdomen. Renal perfusion and RI of the remaining five cats were within normal range (<0.8) and similar to the contralateral kidney at all time points. Endothelialization of the anastomosis was complete with mild-to-moderate fibrosis surrounding the MAC in all cats.

CONCLUSION

End-to-side anastomosis of the renal vein and artery to the vena cava and aorta, respectively, was consistently achieved in all six cats with the MAC.

CLINICAL SIGNIFICANCE

The use of the MAC may be considered as an alternative to hand suturing for ETS anastomoses for feline renal transplantation.