There are few studies focused on cats in the emergency setting. It´s really important to know which parameters need to be monitored and which will be important for prognosis. The purpose of this work was to create an extended database of feline patients admitted as emergencies, so this data would be used to format a prognostic model of survival for this specie, and to help on distribute resources in an optimized way.

Material and Methods

This is a multicentric, prospective and cohort study, that analyzed multiple feline parameters registered during the emergency approach. A total population of 101 cats were consecutively attended in five veterinary hospitals in Spain, Portugal and Brazil, between September, 2005 and January, 2007. All patients were referred as true emergencies and needed hospitalization (Rabelo 2005). The study was based in analyzing complete medical history, and physiologic and laboratorial parameters at the emergency room. All data was checked immediately after patient arriving (T0) and 24 hours after this first moment (T24), and were all condensed in individual files and analyzed by statistical software SPSS 14.0 (SPSS 2001). Parametric data were analyzed by Student´s T Test and non parametric by Pearson´s chi-square and McNemar-Bowker´s Test. In all cases, we consider that all results are significant if p < 0,05.

Results

Total sex frequency were of 59% males (60 animals) and 41% females (41 animals), which generates a male: female ratio of 1.5:1. Median age was 65 months ± 58 months (median ± SD) (1-228 months range). Five breeds were identified (mainly mix breed cats, 71 animals), with a 3.9kg ± 1.4 kg (median ± SD) median weight (0.9-7.4 kg range). The mix organic diseases were the most common cause of admission (33 cases), followed by reproductive-urinary diseases (32 cases), while feline lower urinary tract disease was the most common diagnosis (14 cases). A total of 33 individuals presented renal failure in some degree; 21 suffered from some kind of trauma; 3 had some type of cancer; and one patient presented in cardiac failure. From all patients studied, 74 animals had a medical resolution for their diseases and 27 patients needed surgical approach. Survival at 28 days after the emergency first care was 67.7%.

Discussion and Conclusions

In general, most of the feline patients were admitted for medical problems (80.2%), not related to trauma. A 32.7% of total population presented in some degree of renal failure, and 2.9% had some type of cancer. An important number of feline patients present for acute problems (63.5%), higher than the frequencies seen in humans (Herrera-Gutiérrez et al. 2006), better than an acute decompensation of a chronicle disease (36.5%). Of all cases, more than 2/3 (73.3%) had a medical solution, a number comparable to humans (Herrera-Gutiérrez et al. 2006). The age was an influent factor over mortality in patients with renal failure, as described in humans too (Herrera-Gutiérrez et al. 2006 & Turrentine et al. 2006). In this study, we have used the 28 days survival frequency as our main outcome, since this is the human standard utilized in most survival and prognostic studies (du Cheyron 2005, Löwel et al. 2002, Moran et al. 2008, Phua et al. 2008 & Shapiro et al. 2005). Nevertheless, we have analyzed the 24 hour and 7 days survival after the emergency approach, with the main objective of evaluate if there is any parameter that could impact over short term survival. It´s really important to note that our results show a clear reduction in survival taxes over time. Survival was 98% at 24 hours, 74.2% at 7 days and only 67.7% of all cats were alive 28 days after the emergency approach. This appoints to a tendency that survival at 24 hours is not an accurate parameter to use, since a large number of patients will die during the next 28 days, which would disguise the real seriousness of the problem. This finding would be explained by the efficiency of the initial emergency care, with acute stabilization, that would not be so efficient for a long term survival. Among all clinical parameters checked, only the respiratory rate and rectal temperature presented significant statistically median values along the first 24 hours of hospitalization, even though maintaining physiologic ranges for this specie. In spite of staying in the normal range, the respiratory rate decrease and the rectal temperature increase reflected a positive answer to the stabilization period. Even though not being statistically significant, we think that the hematocrit, electrolytes, pH and bicarbonate variation is clinically important. These findings should be explained by oxygen and fluid administration at the emergency room. The hematocrit decrease was probably caused by hemodilution effect because fluid therapy or by blood loss in some cases. Electrolytes, pH and bicarbonate increase would be explained by fluid administration, but mainly because of perfusion improvement, and compensatory mechanisms to set over against acidosis. The lactate statistically significant decrease was the most important laboratory finding, and is explained by all hemodynamic improvement, with a consequent perfusion stability, one of the most important objectives when treating an emergency patient. The decrease in BUN and creatinine levels along the first 24 hours (T0-T24) was probably caused by fluid therapy too. Glucose levels were not statistically different in T0-T24 interval, but were always higher than the physiologic range (188 and 173 mg/dL respectively) which suggests a feline sensibility to stress and anxiety during and after the emergency care, besides the fact that, in this specie, a possible feedback control failure in controlling glycemic levels would exist in emergency situations. The hyperglycemic state is very common in critical care human patients, and is associated with several alterations as the immunity incapacity, the important inflammatory response, coagulation problems and endothelial reaction (Knieriem et al. 2007). It was not possible to establish the real role of hyperglycemia in veterinary emergency and critical care yet. In spite of not verifying a statistically significant difference between mix venous saturation, it's of concern to note a clinical tendency for a difference, between T0 and T24. The cats in this study had an increase (36% to 56%) in SvO₂ in the first 24 hours. We could try to explain this based on the fact that cats do not present a good sympathetic response to catecholamines as other species do (mainly while in shock and in the presence of hypothermia) (Inoue et al. 2002a, Inoue et al. 2002b, Kawada et al, 2007 & Kitagawa et al. 2003), so they don´t generate an adequate cardiac output sufficient to respond to the hemodynamic aggression. Cats have more vagal innervation than other species, mainly in cervical and thoracic areas, that works almost independently. Some important nodes (celiac, mesenteric, thoracic) fusion with sympathetic branches and suppress its adrenergic effects in several situations (Backman et al.1999, Ohshita et al. 2004, Peterson et al. 1991, Ribeiro et al. 2000 & Tilley & Owen 1987). Without this typical sympathetic response, the cardiac output delay in recover from shock status, and this could explain why mix venous saturation of oxygen is so low in cats that arrive as emergencies (and much lower than in dogs in same circumstances--68%). After the initial treatment, when volemia and temperature are well controlled during the first 24 hours, cats return to respond to adrenergic stimulation, which would be reflected by a decrease in oxygen extraction (or mix venous saturation of oxygen increase). The anion gap decreased probably because of acid-base stabilization (mainly by bicarbonate increase and lactate decrease). All other laboratorial parameters measured did not show any difference between T0 and T24, even so, some of them showed such a big numerical difference that would amaze any clinician, so one need to be aware of this cases (ALP-81 a 157 U/L, ALT-460 a 271 U/L, TCO2-152 a 20 mmHg, for example). Our study suggests that cats have a difficult way to cross while in shock and hypothermic situations, and that most of them would present for a medical problem, not trauma, acutely decompensated, and an important portion of them are in renal failure, very similar to the human data behavior. All of this database will be very important in selecting better protocols and parameters to measure in the emergency setting of feline critical care patients.

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