Page 234 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 17 · Surgery of the diaphragm

the hernia is started at the most dorsal aspect, moving ven- Complications in the early postoperative period may
trally. The ends of the most dorsal sutures are left long and be due to pneumothorax, haemothorax, pleural effusion,
VetBooks.ir lating the rest of the diaphragm in an atraumatic fashion. cardiac arrhythmias (Walker and Hall, 1965; Wilson et al.,
pulmonary oedema, pulmonary atelectasis, shock and
tagged with a haemostat to act as stay sutures for manipu-
1971; Garson et al., 1980; Boudrieau and Muir, 1987).
Choice of suture material and pattern: Although non-
rupture, obstruction or strangulation of the intestinal tract,
absorbable material has been recommended, the very Deaths in the later postoperative period may be due to
long-term support this provides is generally not required. or other unrelated diseases (Garson et al., 1980; Boudrieau
In addition, these materials tend to have sharp ends, which and Muir, 1987).
may traumatize viscera. Ascites may develop after surgery if there is obstruc-
A more rational choice is a synthetic absorbable tion to the hepatic veins following repositioning of the liver,
suture material. Monofilament material, such as polydiox- if herniorraphy has resulted in constriction of the caudal
anone, has the advantage that it is relatively long-lasting, vena cava or if there is chronic liver disease (Downs and
but suffers similar disadvantages to the monofilament Bjorling, 1987). Gastric ulceration has been recorded in
non-absorbable suture material. Multifilament material dogs with chronic ruptures with intrathoracic adhesions
is easier to handle and has greater knot security. There is to an incarcerated liver (Willard and Aronson, 1981).
no one single suture material that will be ideal in Dehiscence of the repair and subsequent reherniation of
all cases, and decisions should be made on an individual abdominal organs is uncommon and is usually due to
animal basis. faulty surgical technique.
An appositional suture pattern is recommended, either
simple interrupted or continuous. The choice of suture Prognosis: The general prognosis for animals with a rup-
material and pattern is less important than meticulous tured diaphragm is guarded to fair. The overall survival rate
atraumatic placement of sutures that appose the edges of has been reported as 52–92% (Wilson et al., 1971; Garson
the diaphragm without tension. The author’s preference is et al., 1980; Stokhof, 1986; Boudrieau and Muir, 1987;
to use simple interrupted sutures with a monofilament Downs and Bjorling, 1987).
absorbable material. A significant proportion, up to 15%, of animals die
Care is taken to avoid constriction of structures running before presentation for anaesthesia and surgical correc-
through the diaphragmatic hiati, e.g. the caudal vena cava, tion. These deaths are generally due to acute reduction in
during herniorrhaphy. In circumcostal tears, it may be diffi- effective lung volume, hypoventilation, shock, multiple
cult to approximate the diaphragm to the abdominal wall, organ system failure and cardiac arrhythmias (Wilson et
and in these cases sutures may be passed around the al., 1971; Garson et al., 1980; Boudrieau and Muir, 1987).
adjacent ribs or the xiphisternum. Another proportion of animals die because of inappro-
priate restraint for examination or other diagnostic inter-
Patching: If atrophy and contracture of the diaphragm in a vention, such as radiography and peritoneal or pleural
chronic hernia make it impossible to close the defect drainage (Wilson et al., 1971; Garson et al., 1980; Stokhof,
with appositional sutures, the defect may be patched with 1986). The other cause of perioperative mortality is
autogenous tissue such as omentum, muscle, liver or induction of anaesthesia. Any delay in intubation and
fascia, or prosthetic materials such as polypropylene the establishment of controlled ventilation may have
mesh, silicone rubber sheeting or lyophilized porcine intes- adverse effects.
tinal submucosa. However, many of these recommenda- If these animals are removed from the analysis then
tions are based on experimental rather than clinical data. the overall mean survival rate for animals subject to surgi-
cal management of a ruptured diaphragm is 79% for
End of the procedure: Closure of the laparotomy incision is dogs and 76% for cats (Garson et al., 1980; Stokhof,
routine. Following reduction of a chronic hernia, replace- 1986; Boudrieau and Muir, 1987). For animals operated
ment of the organs and loss of abdominal domain may on within 24 hours of the trauma, the survival rate was
cause an increase in intraperitoneal pressure and resulting 67% and for those operated on after 1 year, the survival
impairment of venous return. Careful monitoring of cardio- rate was 37% (Boudrieau and Muir, 1987). In a study of
vascular haemodynamics is important. Rarely, in a patient cats with a diaphragmatic rupture, duration of the rupture
with a chronic hernia, the abdominal organs may not fit in was not associated with mortality, but older cats, those
the abdomen because of loss of abdominal domain. In this with low to mildly increased respiratory rates and
case, an elective splenectomy may reduce the volume of those with concurrent injuries had a lower survival rate
the abdominal viscera. (Schmiedt et al., 2003).

Postoperative care and complications: Close monitoring Eventration of the diaphragm
of the cardiopulmonary system is important in the postop-
erative period. Vital signs, mucus membrane colour, capil- This is an uncommon condition that is manifested by bulg-
lary refill time, respiratory pattern and pulse volume, ing of the diaphragm into the thoracic cavity. It is rare, but
quality and rhythm are measured. Supplementary oxygen it has been described in association with hiatal herniation
therapy may be required if there is ventilatory insufficiency. and gastro-oesophageal reflux (Ayres et al., 1978; Merdan
If this persists, aspiration of the chest tube or thoracic Dhein et al., 1980) and in young cats following anaesthesia
radiography should be performed to ensure that this is not for neutering (Gombac et al., 2011). In humans, it may be a
due to continuing pneumothorax. Although continuous or congenital abnormality or may be acquired following
intermittent suction may be used, the most simple and phrenic nerve injury.
practical method is to use intermittent suction with a Congenital diaphragmatic eventration is characterized
syringe every 1–4 hours, depending on the volume of fluid by muscular aplasia of the diaphragm, which may be com-
or air retrieved. The tube should be removed once no more plete or segmental. Acquired eventrations are caused by
pleural air is obtained and once the breathing pattern has injury to the phrenic nerve, with resultant paralysis and
returned to normal. displacement of one or both sides of the diaphragm.

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