Fluid therapy for the traumatized patient

Urinary Tract Trauma in Cats: Stabilisation, Diagnosis and Management

PRACTICAL RELEVANCE

Traumatic injury of the urinary tract may be caused by external accidental trauma or due to iatrogenic injury (typically as a result of catheterisation procedures). Thorough patient assessment and careful attention to patient stabilisation are essential, with diagnosis and surgical repair delayed until the patient is stable, if necessary. Treatment depends on the location and severity of the trauma. If diagnosed and treated promptly, the chance of survival of a patient without other concurrent injuries is good.

CLINICAL CHALLENGES

Following accidental trauma, at the initial presentation urinary tract injury can be overshadowed by other injuries, but if left undiagnosed or untreated it can lead to serious morbidity and potentially mortality. Many of the surgical techniques described for management of urinary tract trauma can be associated with complications, and so comprehensive communication with the owners is necessary.

PATIENT GROUP

The main population affected by urinary tract trauma is young, adult male cats, owing to their roaming behaviour, as well as their anatomy and the resulting increased risk of urethral obstruction and its associated management.

AIMS

This article aims to serve as a guide to all veterinarians who treat cats for the diagnosis and management of urinary tract trauma in cats.

EVIDENCE BASE

This review summarises the current knowledge available from a number of original articles and textbook chapters in the literature that cover all aspects of feline urinary tract trauma, and is supported by the authors' own clinical experience.

High-rise syndrome in cats and dogs

OBJECTIVE

To review the current literature pertaining to the pathophysiology, diagnosis, and treatment of injuries sustained from high-rise syndrome in cats and dogs.

ETIOLOGY

High-rise syndrome is defined as a fall from a height of 2 or more stories that results in a constellation of injuries, including thoracic, abdominal, orthopedic, and orofacial trauma. Animals often fall after slipping from windowsills, engaging in mating behavior, or chasing prey. Cats suffer less severe injuries than dogs due to their "righting reflex" and smaller body mass. Affected animals are younger, and the frequency of falls is higher in warmer months.

DIAGNOSIS

Physical examination coupled with radiographs, ultrasound, and computed tomography can diagnose a myriad of injuries that include pneumothorax, pleural or abdominal effusion, orthopedic fractures, and orofacial injuries. Bloodwork may identify anemia, thrombocytopenia, or increases in hepatic, renal, or pancreatic values consistent with trauma to these organs. Serial venous or arterial blood gas can help determine the severity of respiratory compromise and influence resuscitative efforts. Traditional coagulation tests and thromboelastography can assess trauma-induced coagulopathy and guide transfusion therapy.

THERAPY

Animals presenting in shock require hemodynamic stabilization. Initial resuscitation may incorporate crystalloids, colloids, blood products, and analgesics. Thoracic injuries may require oxygen, thoracocentesis, chest tube placement, and mechanical ventilation. Fractures and wounds are decontaminated and splinted/bandaged, with definitive fixation pursued after stabilization. Abdominal injuries are managed medically unless there is severe ongoing bleeding, sepsis, or injury to the urinary tract.

PROGNOSIS

In feline high-rise syndrome, the prognosis is generally excellent following treatment, with survival exceeding 90%. Canine literature is sparse. The largest retrospective study reported a >90% survival to discharge and a greater need for surgical stabilization in this species. There are no prognostic factors identified that are associated with survival for either species.

Crystalloid and Colloid Compositions and Their Impact

This manuscript will review crystalloid (hypo-, iso-, and hyper-tonic) and colloid (synthetic and natural) fluids that are available for intravenous administration with a focus on their electrolyte, acid-base, colligative, and rheological effects as they relate to each solution's efficacy and safety. The goal is for the reader to better understand the differences between each fluid and the influence on plasma composition, key organ systems, and their implications when used therapeutically in animals with critical illness.

A prospective randomized open-label trial on the comparative effects of 6% hydroxyethyl starch 130/0.4 versus polyionic isotonic crystalloids on coagulation parameters in dogs with spontaneous hemoperitoneum

OBJECTIVE

To evaluate the effects of 6% hydroxyethyl starch 130/0.4 (HES) and a polyionic isotonic crystalloid (CRYS) on standard coagulation tests and rotational thromboelastometry (ROTEM) in dogs with spontaneous hemoperitoneum (SHP).

DESIGN

Prospective randomized open-label clinical study.

SETTING

University teaching hospital.

ANIMALS

Forty-two client-owned dogs presented with SHP.

INTERVENTIONS

Dogs diagnosed with SHP and hypovolemic shock were randomly allocated to receive HES (10 mL/kg, n = 22) or CRYS (30 mL/kg, n = 20) intravenously over 20 minutes for hemodynamic stabilization.

MEASUREMENTS AND MAIN RESULTS

Parameters measured before (T₀ ) and after (T₁ ) treatment were HCT, platelet counts, prothrombin time, activated partial thromboplastin time, fibrinogen concentrations, and extrinsic activated (EXTEM), intrinsic activated (INTEM), and extrinsic activated with platelet inhibition ROTEM assays. Data were analyzed as absolute values and as the percentage change from T₀ to T₁ . No significant differences between groups were detected in any variable at T₀ , and for HCT, platelet counts, prothrombin time, activated thromboplastin time, and fibrinogen concentrations at T₁ . Clot formation time in EXTEM was significantly prolonged (P = 0.037), and maximum clot firmness was significantly decreased (P = 0.038) in the HES group compared to the CRYS group at T₁ . The percentage change in EXTEM clotting time (P = 0.012) and INTEM clot formation time (P = 0.031) was greater after HES than CRYS. Lysis indices remained at 100% for all ROTEM assays in both groups.

CONCLUSION

Compared to a 3-fold volume of CRYS, administration of HES was associated with impairment in ROTEM parameters in dogs with SHP, but no evidence of hyperfibrinolysis was detected.

Review of oncological emergencies in small animal patients

Oncological emergencies can occur at any time during the course of a malignancy and need to be recognized promptly to maximize successful outcomes. Emergencies are characterized as chemotherapy-induced, paraneoplastic syndromes, or directly related to the neoplasm. Prompt identification with treatment of these emergencies can prolong survival and improve quality of life, even in the setting of terminal illness. This review aims to educate the reader on the pathophysiology, clinical presentation and treatment of some of these emergencies, and to review the current veterinary literature to help educate veterinarians in primary and tertiary facilities to know how to diagnose and treat these serious conditions.

Limited fluid volume resuscitation (LFVR) in severe shock unresponsive to initial fluid challenge: A pilot study in 10 cats

OBJECTIVE

To evaluate the effect of limited fluid volume resuscitation (LFVR) administration in cats with severe shock that was unresponsive to initial conventional resuscitation (CR) with isotonic crystalloids.

STUDY DESIGN

Clinical pilot study.

ANIMALS

Ten client-owned cats with non-cardiogenic shock, unresponsive to CR.

METHODS

After an initial ineffective CR with isotonic crystalloids (15-20 mL kg^-1 in 15 minutes), LFVR was started. The animals were randomly assigned to one of two treatments: hypertonic saline alone (group HTS) or HTS and hydroxyethyl starch (HES) (group HTS/HES). A first bolus of HTS (2 mL kg^-1) was administered to both groups, immediately followed by HES (2 mL kg^-1) to group HTS/HES over 5-10 minutes and vital signs were re-evaluated. Additional boluses were administered, every 5-10 minutes, until stabilization (vital parameters, such as temperature, heart rate, respiratory frequency, quality of the pulse and sensorium within the physiological ranges). The time until stabilization (minutes), the volume of HTS and colloid administered and the effect of LFVR on vital parameters were determined.

RESULTS

A mean ± standard deviation (range) volume of 3 ± 2 (2-6) mL kg^-1 of hypertonic saline in group HTS and 4 ± 2 (2-6) mL kg^-1 of both hypertonic and colloidal solutions in group HTS/HES was administered. In six cats (60%), a single bolus of HTS alone (group HTS; n = 3/4) or in combination with HES (group HTS/HES; n = 3/6) was sufficient for stabilization. In the remaining four cases (40%), a second bolus was required. Stabilization occurred in 33 ± 13 minutes (15-60 minutes). Of the 10 cats, six had a positive outcome (6-24 months follow-up) and the others died during hospitalization.

CONCLUSIONS AND CLINICAL RELEVANCE

LFVR appears to be an efficacious treatment for feline shock and may be an alternative therapy for cats unresponsive to CR. Larger cross-sectional and prospective studies are needed to confirm these findings.

A Systematic Review of the Quality of IV Fluid Therapy in Veterinary Medicine

Objective

To evaluate the quality of the veterinary literature investigating IV fluid therapy in dogs, cats, horses, and cattle.

Design

Systematic review.

Procedures

The preferred reporting of items for systematic review and meta-analysis protocols (PRISMA-P) was employed for systematic review of all relevant IV fluid therapy manuscripts published from January 1969 through December 2016 in the Commonwealth Agricultural Bureaux International (CABI) database. Independent grading systems used to evaluate manuscripts included the updated CONsolidated Standards of Reporting Trials 2012 checklist, risk of bias for animal intervention studies, criteria for levels of evidence, and methodological quality (Jadad scale). The quality of articles published before and after 2010 was compared.

Results

One hundred and thirty-nine articles (63 dogs, 7 cats, 39 horses, 30 cattle) from 7,258 met the inclusion criteria. More than 50% of the manuscripts did not comply with minimal requirements for reporting randomized controlled trials. The most non-compliant items included identification of specific predefined objectives or a hypothesis, identification of trial design, how sample size was determined, randomization, and blinding procedures. Most studies were underpowered and at risk for selection, performance, and detection bias. The overall quality of the articles improved for articles published after 2010.

Conclusion and clinical relevance

Most of the veterinary literature investigating the administration of IV fluid therapy in dogs, cats, horses, and cattle is descriptive, does not comply with standards for evidence, or provide adequate translation to clinical practice. Authors should employ and journal editors should enforce international consensus recommendations and guidelines for publication of data from animal experiments investigating IV fluid therapy.

Comparison of the effects of 7.2% hypertonic saline and 20% mannitol on whole blood coagulation and platelet function in dogs with suspected intracranial hypertension - a pilot study

BACKGROUND

Hyperosmolar therapy with either mannitol or hypertonic saline (HTS) is commonly used in the treatment of intracranial hypertension (ICH). In vitro data indicate that both mannitol and HTS affect coagulation and platelet function in dogs. The aim of this study was to compare the effects of 20% mannitol and 7.2% HTS on whole blood coagulation using rotational thromboelastometry (ROTEM®) and platelet function using a platelet function analyzer (PFA®) in dogs with suspected ICH. Thirty client-owned dogs with suspected ICH needing osmotherapy were randomized to receive either 20% mannitol (5 ml/kg IV over 15 min) or 7.2% HTS (4 ml/kg IV over 5 min). ROTEM® (EXTEM® and FIBTEM® assays) and PFA® analyses (collagen/ADP cartridges) were performed before (T0), as well as 5 (T5), 60 (T60) and 120 (T120) minutes after administration of HTS or mannitol. Data at T5, T60 and T120 were analyzed as a percentage of values at T0 for comparison between groups, and as absolute values for comparison between time points, respectively.

RESULTS

No significant difference was found between the groups for the percentage change of any parameter at any time point except for FIBTEM® clotting time. Within each group, no significant difference was found between time points for any parameter except for FIBTEM® clotting time in the HTS group, and EXTEM® and FIBTEM® maximum clot firmness in the mannitol group. Median ROTEM® values lay within institutional reference intervals in both groups at all time points, whereas median PFA® values were above the reference intervals at T5 (both groups) and T60 (HTS group).

CONCLUSIONS

Using currently recommended doses, mannitol and HTS do not differ in their effects on whole blood coagulation and platelet function in dogs with suspected ICH. Moreover, no relevant impairment of whole blood coagulation was found following treatment with either solution, whereas a short-lived impairment of platelet function was found after both solutions.

Bacterial translocation in critical illness

Bacterial translocation involves the passage of intestinal bacteria to extraintestinal sites and has been shown to increase morbidity and mortality in critical illness. This review outlines the pathophysiology of bacterial translocation, host defence mechanisms, and reviews the evidence for the clinical management of critically ill patients in order to minimise the negative outcomes associated with bacterial translocation.

An in vitro comparison of the effects of voluven (6% hydroxyethyl starch 130/0.4) and hespan (6% hydroxyethyl starch 670/0.75) on measures of blood coagulation in canine blood

OBJECTIVE

To assess primary and secondary hemostasis following in vitro dilution of canine whole blood (WB) with hydroxyethyl starch (HES) 130/0.4 and HES 670/0.75.

DESIGN

In vitro experimental study.

SETTING

Private practice, teaching hospital.

ANIMALS

Twenty-five healthy dogs.

INTERVENTIONS

Each dog underwent venipuncture and 18 mL of venous blood was sampled once.

MEASUREMENTS AND MAIN RESULTS

Collected blood was separated in 4 aliquots. Aliquot A served as baseline sample. The remaining tubes of WB were diluted with 0.9% saline, HES 670/0.75 and HES 130/0.4 at a ratio of 1:5.5. Dilutional effects were evaluated using prothrombin time (PT), activated partial thromboplastin time (aPTT), packed cell volume (PCV), thromboelastography (TEG), and platelet closure time (Ct), which was measured using a platelet function analyzer (PFA). Clot strength (ie, G value) was calculated from measured TEG values. Significant increases in PT (P < 0.05) and aPTT (P < 0.05) were documented following WB dilution with saline. Dilution of WB with HES 670/0.75 and HES 130/0.4 resulted in significant hypocoagulable changes in K, MA and G (P < 0.05) compared to baseline and saline. When comparing saline to HES 670/0.75, both R and K values were significantly increased (P < 0.05). K value was significantly increased (P < 0.05) when comparing baseline to HES 130/0.4 and HES 670/0.75. Ct (P < 0.05) was significantly prolonged after WB dilution with HES solutions but not after saline.

CONCLUSIONS

Dilution of WB with HES 670/0.75 and HES 130/0.4 resulted in changes in primary and secondary hemostasis. Although there were small differences between saline and HES 670/0.75, no differences between HES solutions were evident in this small study. This may suggest there would be minimal increases in bleeding risk when either solution is administered to dogs at low doses. Clinical relevance of our findings requires further investigation.

Controversies in the use of hydroxyethyl starch solutions in small animal emergency and critical care

OBJECTIVES

To (1) review the development and medical applications of hydroxyethyl starch (HES) solutions with particular emphasis on its physiochemical properties; (2) critically appraise the available evidence in human and veterinary medicine, and (3) evaluate the potential risks and benefits associated with their use in critically ill small animals.

DATA SOURCES

Human and veterinary original research articles, scientific reviews, and textbook sources from 1950 to the present.

HUMAN DATA SYNTHESIS

HES solutions have been used extensively in people for over 30 years and ever since its introduction there has been a great deal of debate over its safety and efficacy. Recently, results of seminal trials and meta-analyses showing increased risks related to kidney dysfunction and mortality in septic and critically ill patients, have led to the restriction of HES use in these patient populations by European regulatory authorities. Although the initial ban on the use of HES in Europe has been eased, proof regarding the benefits and safety profile of HES in trauma and surgical patient populations has been requested by these same European regulatory authorities.

VETERINARY DATA SYNTHESIS

The veterinary literature is limited mostly to experimental studies and clinical investigations with small populations of patients with short-term end points and there is insufficient evidence to generate recommendations.

CONCLUSIONS

Currently, there are no consensus recommendations regarding the use of HES in veterinary medicine. Veterinarians and institutions affected by the HES restrictions have had to critically reassess the risks and benefits related to HES usage based on the available information and sometimes adapt their procedures and policies based on their reassessment. Meanwhile, large, prospective, randomized veterinary studies evaluating HES use are needed to achieve relevant levels of evidence to enable formulation of specific veterinary guidelines.

A pilot comparison of limited versus large fluid volume resuscitation in canine spontaneous hemoperitoneum

Treatment for hemorrhagic shock secondary to a spontaneous hemoperitoneum includes restoration of IV volume and surgical control of hemorrhage. This study was designed to determine if limited fluid volume resuscitation (LFVR) with hypertonic saline (HS) and hyperoncotic fluids (hydroxyethylstarch [HES]) results in more rapid cardiovascular stabilization in dogs with spontaneous hemoperitoneum versus conventional resuscitation (CR) with large volume resuscitation. Eighteen client-owned dogs presenting in hemorrhagic shock with a spontaneous hemoperitoneum were enrolled. Dogs were randomized to be fluid resuscitated with up to 90 mL/kg of an isotonic crystalloid (CR group) or up to 8 mL/kg of 7.2% Na chloride (i.e., HS) combined with up to 10 mL/kg of 6% HES. Measurements of vital signs, lactate, packed cell volume (PCV), total solids (TS), and blood pressure were made at standard time points. The primary end point was time to stabilization of hemodynamic parameters (measured in min). Dogs in the LFVR group achieved hemodynamic stabilization significantly faster (20 min; range, 10-25 min) than those in the CR group (35 min; range, 15-50 min; P = .027). Future studies are warranted to further investigate potential benefits associated with LFVR in dogs with spontaneous hemoperitoneum.

In vitro effect of hydroxyethyl starch 130/0.42 on canine platelet function

OBJECTIVE

To evaluate the effect of 6% hydroxyethyl starch (HES) solution, with a molecular weight of 130 kDa and a degree of substitution of 0.42, on canine platelet function in vitro.

SAMPLES

Blood samples from 31 healthy adult dogs.

PROCEDURES

Citrated blood was diluted with saline (0.9% NaCl) solution or HES 130/0.42 in ratios of 1:9 (ie, 1 part saline solution or HES 130/0.42 and 9 parts blood) and 1:3. Platelet plug formation time (closure time [Ct]) was measured with a platelet function analyzer and cartridges coated with collagen and ADP.

RESULTS

Median baseline Ct with citrated blood was 84.0 seconds (interquartile range, 74.5 to 99.5 seconds). Results obtained with 1:9 dilutions with saline solution and HES 130/0.42 were not significantly different from baseline results. The 1:3 dilutions with saline solution and HES 130/0.42 resulted in median Cts of 96.0 seconds (interquartile range, 85.5 to 110.8 seconds) and 112.0 seconds (92.0 to 126.0 seconds), respectively. Results obtained with both 1:3 dilutions were significantly different from baseline results. The Ct obtained with the HES dilution was also significantly different from that of the 1:3 dilution with saline solution.

CONCLUSIONS AND CLINICAL RELEVANCE

Saline solution and HES 130/0.42 in a 1:3 dilution affected canine platelet function by prolonging Cts. The HES 130/0.42 had a significantly greater effect on canine platelets than did saline solution.