Hypovolemic shock and resuscitation

Chronic axillary wounds in cats: what do we know and how should we manage them?

PRACTICAL RELEVANCE

Axillary wounds most often occur in outdoor cats that wear a collar, typically after having been missing. These wounds are commonly chronic and indolent in nature, and although there is so far no consensus on an explanation for this, it is likely that there are several factors involved.

CLINICAL CHALLENGES

Axillary wounds are often difficult to manage due to the frequent presence of infection, their histopathological characteristics and their location, where there is excessive tension and movement of the axillary tissues. Initial surgical treatment has a high reported incidence of failure and complications in the literature, with wound breakdown reported most commonly. Giving due consideration to the difficulties of managing these wounds, however, will help practitioners to decrease the occurrence of complications and the need for multiple procedures, and therefore improve the outcome.

EQUIPMENT

Initial approach and surgical management can be achieved using standard medical equipment and surgical kit available to general practitioners.

EVIDENCE BASE

This review discusses the surgical techniques reported in the literature to have successfully treated chronic axillary wounds and recommendations are also provided based on the authors' clinical experience.

Infusão contínua de lidocaína em diferentes taxas no controle de arritmias induzidas pela administração de adrenalina em cães anestesiados com isofluorano

Avaliaram-se os efeitos da infusão de diferentes doses de lidocaína sobre o ritmo cardíaco, em cães anestesiados com isofluorano que receberam doses crescentes de adrenalina. Foram utilizados 10 cães, cada qual anestesiado quatro vezes, respeitando-se um intervalo de duas semanas. A indução anestésica foi realizada com propofol, 8mg/kg, e a manutenção com isofluorano a 1,5 CAM. Os animais foram distribuídos em quatro grupos, que receberam bolus de lidocaína, 1mg/kg, seguido pela infusão de lidocaína nas taxas de 50μg/kg/h (G50), 100μg/kg/h (G100) e 200μg/kg/h (G200). O grupo-controle (GC) recebeu bolus e infusão de NaCl a 0,9%. As variáveis foram mensuradas 30 minutos após a indução, e em seguida, iniciadas as infusões. Após 10 minutos do princípio dos tratamentos, colheram-se novamente os dados e iniciou-se a infusão de adrenalina, 1μg/kg/min. Em intervalos de 10 minutos, realizou-se nova colheita de dados e acrescentou-se 1μg/kg/min na taxa de infusão de adrenalina, até atingir 5μg/kg/min. Comparativamente ao GC, ocorreu redução do aparecimento de batimentos de origem não sinusal e bloqueios atrioventriculares de segundo grau nos grupos tratados com lidocaína. Concluiu-se que a associação de lidocaína à anestesia com isofluorano diminuiu o aparecimento de irregularidades no ritmo cardíaco.

Efeitos da solução salina hipertônica a 7,5% em glicose a 5% nas concentrações séricas de sódio, cloreto e potássio de eqüinos com hipovolemia induzida

Estudaram-se os efeitos de soluções salinas isotônica e hipertônica em eqüinos hipovolêmicos sobre as concentrações séricas de sódio, cloreto e potássio e freqüências cardíaca (FC) e respiratória (FR). Quinze eqüinos machos com peso entre 390 e 475kg e idades entre quatro e 18 anos foram submetidos à retirada de sangue correspondente a 2% do peso corporal e distribuídos em três grupos de igual número: o grupo GSH recebeu solução hipertônica de NaCl a 7,5% em glicose a 5%; o GSI, solução isotônica de NaCl a 0,9%; e o GC não foi tratado. Os eletrólitos séricos foram avaliados antes (T0), após a retirada de sangue (T1) e após a infusão das soluções, entre 20 e 30 minutos (T2), entre 60 e 70 minutos (T3) e entre 120 e 130 minutos (T4). Após T0, houve elevação da FC e da FR, e as concentrações séricas de Na, Cl, K permaneceram inalteradas. Após a infusão, houve melhora das variáveis clínicas em GSI e GSH, em relação ao GC. Quanto a T3 e T4, os valores de Na em T2 do GSH foram maiores, e os de Cl e de K não se alteraram. As soluções hipertônica e isotônica são seguras na correção da hipovolemia induzida e não produzem alteração eletrolítica significativa.

Hemodynamic Characteristics of Vasopressin in Dogs with Severe Hemorrhagic Shock

The effect of vasopressin was compared with that of the established vasopressor epinephrine in experimentally induced hemorrhagic shock. After rapid crystalloid resuscitation in a ratio of three volumes of 0.9% saline to one volume of blood (3:1 crystalloid resuscitation), six dogs were given 0.4 IU/kg vasopressin and another six dogs were given 0.1 mg/kg epinephrine. Five dogs in the control group were given fluid resuscitation in the same manner as above without administration of any drugs. Administration of vasopressin increased diastolic arterial pressure (DAP) from 45.0 +/- 4.9 to 91.2 +/- 9.6 mmHg within 5 min, compared with epinephrine from 46 +/- 4.0 to 51.8 +/- 7.7, and control from 47.3 +/- 7.5 to 46.3 +/- 7.3. Systolic arterial pressure (SAP) did not increase significantly following vasopressin compared with epinephrine and control group. Results of DAP and systemic vascular resistance index (SVRI) suggested that vasopressin administration was vasoconstrictive after fluid resuscitation in decompensatory hemorrhagic shock in dogs, whereas epinephrine did not compared with control. In addition, epinephrine did not affect the cardiac index (CI) and SVRI, while a significant decrease in CI and increase in SVRI were observed in vasopressin group. The pressor effect of epinephrine in the vascular system was abrupt and only lasted a short period of time (within 5 min), while that of vasopressin was steady and lasted for more than 1 hr, especially regard to in DAP. When compared with epinephrine, vasopressin can be a more effective and safer choice in patients with severe hemorrhagic shock.

Preoperative evaluation and management of the emergency surgical small animal patient

The initial management and stabilization of the emergency surgical patient is challenging. A consistent systematic evaluation of the four major body systems, determination of the underlying cause, and aggressive stabilization before surgery can optimize the outcome.

Comparison of systemic and renal hemodynamics measured by Doppler ultrasonography in canine experimental hypovolemia

The aim of this study was to examine renal hemodynamics at the hypovolemic and recovery phases in two different hypovolemic shock models using Doppler ultrasonography, and to compare this with systemic hemodynamics. In experiment 1, the hypovolemic phase was induced in 6 mongrel dogs by removing arterial blood at 30 ml/kg for 60 min. In the recovery phase, this blood was reinfused at 30 ml/kg over 60 min. In experiment 2, hypovolemia was induced in 12 beagle dogs by rapid blood removal until blood pressure decreased to 40 mmHg and was maintained at this pressure for 30 min. Six of the dogs were then infused with 20 ml/kg hydroxyethyl starch over 5 min, and the other 6 were infused with 60 ml/kg lactated Ringer's solution also over 5 min. Parameters for systemic and renal hemodynamics were measured by using a polygraph and the Doppler method, respectively. The decrease of diastolic blood flow, resulted in an increase of vessel resistance, and was detected in the hypovolemic kidney by the Doppler method. The rapid and large volume infusion of resuscitation fluids was effective for the recovery of both systemic circulation and renal blood flow, however this induced an increase of kidney vessel resistance, a result of the autoregulation mechanism of the kidney. The changes in these parameters at the main renal artery and interlobar artery were similar.

Transfusion therapy in emergency and critical care medicine

The administration of blood or its components can provide the life-saving element for a critically ill small animal patient. Shock from acute massive hemorrhage produces catastrophic cardiovascular changes requiring rapid, accurate resuscitation techniques for survival. Bleeding that occurs more slowly allows for the opportunity to discover and treat the inciting cause and to administer specific blood component.