Biology Reference
In-Depth Information
symptoms/signs as predictors of bleeding and azotemia. These investigators reported
that clinical complications were unlikely in patients with hemoglobin 13 g/dL;
platelet count 100,000/mm 3 ; blood urea 7 mmol/L; and an absence of protein-
uria or bleeding (Porath et al., 1992). Importantly, these authors found that treatment
on admission with monovalent antivenom was associated with a shorter duration of
hemostatic dysfunction, while provision of FFP did not appear effective in prevent-
ing complications (Porath et al., 1992).
In a prospective survey of 100 patients envenomed by Crotalus durissus (tropical
rattlesnake) in Brazil, other biochemical disturbances were identified as precursors
of AKI (Pinho et al., 2005). These authors reported that among the 29 patients in
their series who developed AKI, 24% required dialysis, and 10% died. The patients
with AKI had smaller body area in comparison to envenomated patients without
AKI; lower urinary output on admission; a marked CK increase; and had received
antivenom later than other patients and/or received a lower dose (Pinho et al.,
2005). Patient age 12 years, provision of antivenom 2 h postadmission, and a
CK 2000 U/L were all identified as independent risk factors for AKI. Diuresis
90 mL/h was deemed a protective factor (Pinho et al., 2005).
Coagulopathic envenoming from some elapids also present with a similar set of
concerns. For instance, among 32 cases of Pseudonaja spp. (Australian brown snakes)
envenoming with severe consumptive coagulopathy enrolled in the Australian snake-
bite project, four had thrombotic microangiopathy (Isbister et al., 2007). These patients
exhibited thrombocytopenia that was most severe 3 days postenvenoming and required
1 week to normalize. All showed erythrocyte fragmentation, and most developed AKI
that persisted for 2-8 weeks and required dialysis (Isbister et al., 2007). These authors
included two additional cases of Pseudonaja spp. envenoming that had features shared
with those in their enrolled series. Importantly, although all six patients received anti-
venom, provision of antivenom was delayed in comparison to other Pseudonaja spp.
envenoming cases studied. Four patients were treated with plasmapheresis that did not
appear to provide any significant clinical benefit (Isbister et al., 2007).
These brief representative cases involving viperids and elapids suggest venom-
induced renal sequelae similar to that from some hazard level 1 colubrids. In all of these
cases, thrombocytopenia, anemia, probable intravascular hemolysis, altered erythrocyte
morphology, possibly, microangiopathic thrombosis, and delayed or absent antivenom
provision all are associated with serious renal dysfunction. Although some authors
report improvement in a sampling of patients treated with dialysis or plasmapheresis
(Mori et al., 1983; Pinho et al., 2005), many patients with consumptive coagulopathy/
DIC from envenomation by colubroids with venoms that contain prothrombin-activating
or thrombin-like enzymes do not respond to these measures and often have extended
periods of renal dysfunction (see previous sections and Table 4.1 ). This can have long-
term implications for envenomed patients. Several studies have demonstrated a sig-
nificant association between AKI and long-term morbidity and mortality (Bihorac et
al., 2010; Coca et al., 2009). An additional retrospective matched cohort study con-
cluded that acute renal injury requiring dialysis was significantly associated with
increased risk of end-stage renal disease, but unrelated to all-cause mortality (Wald et
al., 2009). Therefore, although long-term mortality risk associated with AKI is arguably
Search WWH ::




Custom Search