Life-threatening hemorrhage from enterotomies and anastomoses in 7 horses

Repeat Celiotomy-Current Status

Repeat celiotomy can be lifesaving in horses with a surgically treatable postoperative obstruction, although guidelines for its use are lacking, except for uncontrollable postoperative pain. Overdiagnosis of ileus as the cause of postoperative obstruction could delay a second surgery so the disease progresses beyond a manageable level of severity. Although many horses respond favorably to repeat celiotomy, complications can be severe and life threatening, such as incisional infection and adhesions. Repeat celiotomy does not seem to exacerbate postoperative ileus, despite additional surgical manipulation. An important benefit of repeat celiotomy is termination of hopeless cases, thereby reducing cost and suffering.

Ex vivo evaluation of a technique for equine jejunocecal anastomosis using radiofrequency thermofusion and a Cushing oversew

OBJECTIVE

To describe a technique for a side-to-side jejunocecal anastomosis in horses using radiofrequency thermofusion (TF) of the intestines supported by a Cushing oversew and to compare this anastomosis to handsewn and stapled techniques.

STUDY DESIGN

Ex vivo study.

SAMPLE POPULATION

Intestinal tracts from 24 slaughtered horses.

METHODS

A radiofrequency device was used to perform a jejunocecal anastomosis (Group RFA). The construction time and bursting pressure of this construct were compared with those of a hand-sewn double layer (Group HS) and stapled anastomoses (Group ST) without oversew of the staple line. Histology was also performed for the TF anastomoses to evaluate the extent of the thermal damage.

RESULTS

The median (range) construction time (min) for the TF (15.8 [14.4-16.8]) was not significantly different from that for the HS (25.5 [24.2-26.3]) and ST (10.8 [9.7-12.5]) groups (p = .07). The construction time for ST was shorter than that for HS group (p < .001). The average (standard deviation) bursting pressure (mmHg) for HS (153.1 +/- 17.5) was higher than that for RFA (76 +/- 15) and ST groups (48 +/- 13; p < .001). The bursting pressure of the RFA was higher than that of the ST anastomoses (p = .001). The thermal damage caused by the device was within the suture oversew in the deeper layers, whereas it extended a few mm beyond the suture line in the serosa.

CONCLUSION

Radiofrequency assisted anastomoses provide similar construction times to current techniques and have a higher bursting pressure than ST anastomoses.

CLINICAL SIGNIFICANCE

Radiofrequency-assisted anastomoses with a suture oversew demonstrated comparable bursting pressures to ST anastomoses. The use of the radiofrequency device on the intestine is extra label and causes serosal tissue damage, which may increase the risk of adhesions.

Transillumination techniques for vessel identification during small colon resection in six horses

BACKGROUND

Transillumination has been described in human surgery to improve vessel visualization but has not been described in horses. Since the equine mesocolon contains a great amount of fat which restricts visualization of the vessels, this technique could be useful during small colon resection.

OBJECTIVES

To describe transillumination of the mesocolon to provide an improved vessel identification during resection and anastomosis of the small colon in horses.

METHODS

Data of horses that underwent resection and anastomosis of small colon were recorded. Two transillumination techniques were used during resection and anastomosis of small colon. In a first technique, used on three horses, the operating lamp was used. It was lowered and tilted so that the assistant surgeon could lift the small colon so that the mesentery was between the lamp and the first surgeon eyes. In a second technique, used on further three horses, a smartphone with a rear LED flashlight turned on was placed into a sterile rectal sleeve. The device was placed on the surgical field and the portion of small colon to be resected was then laid over the smartphone, to backlight the vessels. The vessels were then identified and ligated.

RESULTS

Six horses referred for acute colic that underwent resection and anastomosis of the small colon were included in the study. Using both transillumination technique the mesocolon was backlit and the vessels were clearly and easily identified, dissected, ligated, and transacted without complications. The smartphone technique subjectively ensured a better operating position for the surgeon and less fatigue for the assistant.

CONCLUSIONS

Transillumination techniques are useful to avoid damage when ligating vessels and using the flashlight of a smartphone is easier and provide safer and more accurate transection of them during small colon resection and anastomosis.

The pathophysiology of uncontrolled hemorrhage in horses

BACKGROUND

Hemorrhagic shock in horses may be classified in several ways. Hemorrhage may be considered internal versus external, controlled or uncontrolled, or described based on the severity of hypovolemic shock the patient is experiencing. Regardless of the cause, as the severity of hemorrhage worsens, homeostatic responses are stimulated to ameliorate the systemic and local effects of an oxygen debt. In mild to moderate cases of hemorrhage (<15% blood volume loss), physiological adaptations in the patient may not be clinically apparent. As hemorrhage worsens, often in the uncontrolled situation such as a vascular breach internally, the pathophysiological consequences are numerous. The patient mobilizes fluid and reserve blood volume, notably splenic stored and peripherally circulating erythrocytes, to preferentially supply oxygen to sensitive organs such as the brain and heart. When the global and local delivery of oxygen is insufficient to meet the metabolic needs of the tissues, a cascade of cellular, tissue, and organ dysfunction occurs. If left untreated, the patient dies of hemorrhagic anemic shock.

CLINICAL IMPORTANCE

An understanding of the pathophysiological consequences of hemorrhagic shock in horses and their clinical manifestations may help the practitioner understand the severity of blood volume loss, the need for referral, the need for transfusion, and potential outcome. In cases of severe acute uncontrolled hemorrhage, it is essential to recognize the clinical manifestations quickly to best treat the patient, which may include humane euthanasia.

KEY POINTS

Uncontrolled hemorrhage may be defined as the development of a vascular breach and hemorrhage that cannot be controlled by interventional hemostasis methods such as external pressure, tourniquet, or ligation. Causes of uncontrolled hemorrhage in horses may be due to non-surgical trauma, surgical trauma, invasive diagnostic procedures including percutaneous organ biopsy, coagulopathy, hypertension, cardiovascular anomaly, vascular damage, neoplasia such as hemangiosarcoma, toxicity, or idiopathic in nature. When a critical volume of blood is lost, the respondent changes in heart rate, splenic blood mobilization, and microcirculatory control can no longer compensate for decreasing oxygen delivery to the tissues In spite of organ-specific microvascular responses (eg, myogenic responses, local mediator modulation of microvasculature, etc), all organs experience decreases in blood flow during severe hypovolemia Acute, fatal hemorrhagic shock is characterized by progressive metabolic acidosis, coagulopathy, and hypothermia, often termed the "triad of death," followed by circulatory collapse.

Prevention of post operative complications following surgical treatment of equine colic: Current evidence

Changes in management of the surgical colic patient over the last 30 years have resulted in considerable improvement in post operative survival rates. However, post operative complications remain common and these impact negatively on horse welfare, probability of survival, return to previous use and the costs of treatment. Multiple studies have investigated risk factors for post operative complications following surgical management of colic and interventions that might be effective in reducing the likelihood of these occurring. The findings from these studies are frequently contradictory and the evidence for many interventions is lacking or inconclusive. This review discusses the current available evidence and identifies areas where further studies are necessary and factors that should be taken into consideration in study design.

Handsewn semiclosed single-layer jejunocecal side-to-side anastomosis in the horse

OBJECTIVE

To report a technique for semiclosed 1-layer side-to-side jejunocecal anastomosis in horses.

STUDY DESIGN

Experimental study and clinical reports.

SAMPLE POPULATION

Part 1--In vitro: Intestinal specimens from 24 horses collected immediately after death at an abattoir. Part 2--CLINICAL CASES: 10 horses with clinical signs of colic requiring jejunocecostomy.

METHODS

Mean time to perform twelve 2-layer handsewn (HS2L) and 12 semiclosed 1-layer modified handsewn (SC) jejunocecal anastomoses was compared. Mean bursting pressures of anastomoses measured with a modified tank inflation test were compared. The SC technique was used in 10 horses that required jejunocecal anastomosis with and without resection (complete or incomplete ileocecal bypass).

RESULTS

The SC technique was significantly quicker to perform than HS2L technique. Clinically, the technique appeared safe with a major complication, associated with obstruction from kinking of the anastomosis, occurring in 1 horse.

CONCLUSIONS

The SC technique was easy to perform with very little mucosal exposure in comparison to the HS2L technique, and was safe and effective in restoring intestinal continuity in clinical cases.

CLINICAL RELEVANCE

The SC technique should be considered for jejunocecostomy in horses because it reduces anastomosis time and mucosal exposure compared with other techniques.

Changes in central venous pressure and blood lactate concentration in response to acute blood loss in horses

OBJECTIVE

To evaluate selected hemodynamic, blood gas, and biochemical responses to mild to moderate acute blood loss in standing, awake horses.

DESIGN

Prospective study.

ANIMALS

7 healthy mares.

PROCEDURES

Each horse was restrained in standing stocks, and its head was maintained in a neutral position; sedatives and tranquilizers were not administered. During a 1-hour period, blood was collected into collection bags by use of a suction pump. The rate of blood collection was approximately 16 mL/kg/h (7.3 mL/lb/h). Thirty minutes after blood collection, the blood was readministered at the same rate. Central venous pressure (CVP), central venous blood gas, blood lactate concentration, and heart rate were measured at baseline (after placement of catheters), after removal of blood, and after readministration of blood.

RESULTS

In response to blood loss, CVP decreased and blood lactate concentration increased significantly, compared with baseline values; heart rate and results of central venous blood gas analysis did not change significantly. After readministration of blood, CVP returned to baseline value and blood lactate concentration approached baseline value.

CONCLUSIONS AND CLINICAL RELEVANCE

Changes in CVP and blood lactate concentration appear to be early indicators of hypovolemia in horses, which may represent acute blood loss in trauma patients; these variables should be monitored to assess the potential need for blood transfusions. These variables can be used to monitor responses of horses to blood transfusions when whole blood is administered as the replacement fluid.

In Vitro Evaluation of an Inverted End-to-End Equine Jejunojejunal Anastomosis Using Skin Staples

OBJECTIVE

To compare functional indices of end-to-end (EEA) jejunojejunal anastomosis using skin staples in horses with a 2-layer inverting hand-sewn technique.

STUDY DESIGN

Experimental study.

SAMPLE POPULATION

Jejunal segments from 8 fresh equine cadavers.

METHODS

For each bowel segment, 2 EEA anastomoses were created: one 2-layer hand-sewn and one 1-layer using skin staples. Time for anastomosis creation was recorded and compared. Lumen diameter of each anastomosis was measured on digital radiographs after intraluminal instillation of contrast medium and inflation of the jejunal segments to 14 mm Hg. Anastomotic indices (a compensated measure of stoma diameter) and bursting pressure were determined.

RESULTS

EEA jejunal anastomosis using skin staples was significantly faster than use of a 2-layer hand-sewn technique. Anastomotic index, a measure of lumen size, was significantly larger with the skin-staple technique; however, the bursting pressure of stapled anastomoses was significantly less than for the hand-sewn technique, but the values were well above those reported for other anastomotic techniques.

CONCLUSIONS

An anastomotic technique using skin staples was easy to learn and perform, effective and faster, and mechanically comparable with a hand-sewn 2-layer technique.

CLINICAL RELEVANCE

The staple technique could be beneficial in equine gastrointestinal surgery by reducing anastomosis time, although further in vivo studies are needed to establish clinical safety.

In Vitro Evaluation of a Closed-Bowel Technique for One-Layer Hand-Sewn Inverting End-to-End Jejunojejunosotomy in the Horse

OBJECTIVE

To report a technique for closed-bowel 1-layer inverting end-to-end jejunojejunal anastomosis in horses.

STUDY DESIGN

Experimental study.

SAMPLE POPULATION

Fresh cadaveric jejunal segments from 12 horses.

METHODS

For each bowel segment a 1-layer closed and a 2-layer inverting end-to-end jejunojejunosotomy was created. Anastomosis construction time and anastomotic bursting pressure were measured and compared.

RESULTS

Closed-bowel anastomosis was significantly faster to create than a 2-layer technique. Luminal narrowing (<30%) was similar with both techniques and comparable with other inverting techniques. Bursting pressure was significantly higher for the 2-layer technique, although all anastomoses resisted pressures higher than those reported for other jejunojejunal anastomosis techniques.

CONCLUSIONS

A 1-layer hand-sewn, closed, inverting jejunojejunosotomy using a modified Doyen clamp was easy and faster to perform, and resulted in functional characteristics similar to, a 2-layer hand-sewn inverting technique.

CLINICAL RELEVANCE

A closed, 1-layer inverting technique could be considered for equine jejunal anastomosis but requires in vivo evaluation before recommendation for clinical use.