Pneumothorax and Diaphragmatic Hernias Flashcards
1
Q
What is a pneumothorax characterized by? (2)
A
Pneumothorax is characterised by a rapid, shallow breathing pattern (tachypnoea but hypoventilation) with reduced/absent lung sounds
2
Q
How is a pneumothorax most commonly diagnosed in a stable patient?
A
Radiographs
3
Q
What is initially performed in a pneumothorax?
A
Thoracocentesis
4
Q
When is a thoracostomy tube required for a pneumothorax? (2)
A
- when repeated thoracentesis required
- negative pressure cannot be achieved
5
Q
When is surgery indicated for a pneumothorax? (3)
A
- Significant wounds
- Failure of the pneumothorax to resolve after 5 days of intermittent/continuous suction,
- Abnormality seen on radiography/CT
6
Q
What are the pathogenesis of a pneumothorax? (6)
A
- Penetration of thoracic wall
- Penetration of oesophagus
- Penetration of airways
- Iatrogenic
- Primary spontaneous
- Secondary spontaneous
7
Q
What is the causes of secondary spontaneous pneumothorax?
A
The lung is the cause of the leak, with clinical evidence of pulmonary disease e.g., bacterial pneumonia, chronic obstructive lung diseases, asthma, tuberculosis, fungal granuloma, neoplasia, ruptured pulmonary abscesses, heartworm thromboembolism (causing bronchopleural communications) etc.
8
Q
What is the causes of primary spontaneous pneumothorax?
A
The lung is the cause of the leak, but there is no clinical evidence of pulmonary disease. In this case, pneumothorax is secondary to rupture of pulmonary blebs (local accumulations of air within the visceral pleura) or bullae (confluent alveoli). This condition has been reported most commonly in large, deep chested breeds of dogs. The aetiology of the pulmonary blebs and bullae are unknown in dogs.
9
Q
How does a tension pneumothorax develop?
A
From a closed pneumothorax where soft tissue acting as a one-way valve allows air to enter the pleural space during inspiration, but not to exit during expiration.
10
Q
How does a tension pneumothorax cause death within minutes?
A
supra-atmospheric pressure, which severely compromises ventilation and venous return, and leads to death
11
Q
What is seen on x-ray with a tension pneumothorax? (4)
A
- Large volume of pleural air visible.
- Marked lobar collapse
- Mediastinal shift to the right
- A flattened left hemidiaphragm.
12
Q
What radiographic signs are consistent with pneumothorax? (4)
A
- Increased radiolucency and absence of pulmonary vasculature in the periphery of the thoracic cavity
- Dorsal elevation of the cardiac silhouette
- Increased parenchymal radiopacity
- Pneumomediastinum
13
Q
What is a CT scan better at detecting with a spontaneous pneumothorax?
A
Blebs
Bullae
14
Q
How often should a thoracostomy tube be evacuated?
A
Every 2-4 hours
15
Q
When can a thoracostomy tube be removed following a pneumothorax?
A
When production is nil
16
Q
When should continuous suction be used in a thoracostomy tube for pneumothorax? (2)
A
- Air reaccumulates rapidly following thoracic percutaneous drainage (e.g., PleuralPort) for pneumothorax,
- Negative pressure cannot be reached
17
Q
Other than surgery/thoracostomy tubes. What other techniques have been described? (2)
A
- Autologous blood patch pleurodesis
- PleuralPort
18
Q
Name post-operative complications of a pneumothorax (7)
A
- Recurrent pneumothorax
- Haemorrhage
- Pyothorax
- Pneumonia
- Sepsis
- Reflux oesophagitis
- Wound complications.
19
Q
In cats, what is a spontaneous pneumothorax almost exclusively associated with? Give examples (5
A
Lung disease
- Inflammatory airway disease
- Neoplasia
- Heartworm
- Lungworm
-Abscessation
20
Q
When should surgery be performed urgently in traumatic diaphragmatic hernia?(3)
A
- Gastric entrapment and tympany;
- Ongoing haemorrhage or hypovolaemia;
- Severe/relentless abdominal pain.
21
Q
What must happen before surgical repair of a diapragmatic hernia?
A
cardiovascular stabilisation
22
Q
What surgical closure is performed on a traumatic diaphragmatic hernia?
A
Primary apposition
23
Q
How often are complications in a traumatic diaphragmatic hernia repair?
A
50%
24
Q
Survival to discharge in traumatic diaphragmatic hernia?
A
89%
25
What diaphragmatic hernia is congenital
Peritoneo-pericardial diaphragmatic hernia (PPDH)
26
How can we manage non symptomatic patietns with a PPDH?
Conservative tx with monitoring.
27
How do we manage PPDH patients who are symptomatic?
Surgery
28
PPDH surgery survival rate - dogs?
82-100%
29
PPDH surgery survival rate - cats?
86%
30
What is the complication rate of PPDH surgery?
78%
31
What "type" of structure is the diaphragm?
Musculotendinous
32
What are the physical roles of the diaphragm? (2)
- Ventillation
- Assist in lymphatic drainage
33
What are the 3 types of diaphragmatic hernia and where are these located?
- Along the fibre orientation of the costal musculature (radial tear, seen in 45% of cases),
- The muscular attachment to the ribs (circumferential tear, seen in 23% of cases),
- A combination of both
34
What is the most common organ to herniate through the diaphragm?
Liver
35
Are traumatic diaphragmatic hernia acute or chronic at presentation?
Either
36
Clinical signs of a diaphragmatic hernia (15)
Dyspnoea (41.1%)
Muffled heart sounds (29.4%)
Vomiting (11.7%)
Anorexia
Diarrhoea
Open mouth breathing
Cyanosis
Cachexia
Icterus
Increased or decreased lung sounds
Exercise intolerance
Shock
Cardiac arrhythmia
Pale mucous membranes
Hypothermia.
37
What type of injuries do patients have concurrently with a diaphragmatic hernia:
A) 27%
B) 33.3%
A) Soft tissue
B) Orthopedic
38
What causes respiratory compromise in a diaphragmatic hernia? (5)
- Loss of the mechanical function of the diaphragm
- Pleural space-occupying effect of abdominal organs (plus associated air or fluid accumulation),
- Compression of lung lobes
- Atelectasis of lung lobes
- Ventilatory impairment
39
What is the end results of significant hypoventilation and alveolar ventilation-perfusion mismatch in a diaphragmatic hernia?
Life threatening hypoxia
40
How many dogs with a diaphragmatic hernia have a cardiac arrythmia?
12%
41
Why do cardiac arrythmias occur with a diaphragmatic hernia?
Herniation of abdominal viscera may compress the thoracic caudal vena cava, decreasing venous return and reducing cardiac output.
42
Other than physical herniation, what else with a diaphragmatic hernia causes cardiac function effects? (3)
Traumatic myocarditis
Poor oxygen delivery
Hypovolaemic shock
43
If abdominal organs herniated into the thoracic cavity can become entrapped and strangulated, leading to accumulation of transudate, adhesion formation, and visceral torsion, perforation or necrosis. What is needed?
Resection of affected tissue is required in such patients.
44
How many cases does xrays for a diaphragmatic hernia achieve a diagnosis?
70%
45
What is seen on xrays of a diaphragmatic hernia (6)
- Partial loss of the normal line of the diaphragm (seen in up to 97% of patients),
- Herniation of small intestines or other viscera (up to 61% and 35% respectively),
- Obscured or displaced cardiac silhouette,
- Lung collapse,
- Rib fractures
- Pleural fluid
46
How many patients can U/S diagnose organ herniation and loss of diaphragmatic line?
90%
47
What is the main disadvantage of CT in patients with diaphragmatic hernia?
GA required
48
In recent studies, is it better to surgically intervene within 24 hours or delay surgery in acute and chronic diaphragmatic hernia?
Early
49
What other considerations are there when deciding on surgical timing of diaphragmatic hernias? (4)
Cardiopulmonary dysfunction
Respiratory compromise
Organ entrapment
Anaesthesia stability
50
What pulmonary pressures should be avoided in diaphragmatic hernias?
>20cm H20
51
When should a diaphragmatic hernia receive prophylactic antiobiosis?
Patients with liver or biliary tract herniation
52
Which bacteria can occur in incarcerated liver lobes?
Clostridial
53
How should a patient be positioned for diaphragmatic hernia Sx repair?
Dorsal recumbency, with table tilted such that head is elevated.
54
If there is a unilateral hernia, how may the positioning of the patient differ?
The affected side being tilted downwards to reduce compression of functional lung.
55
Diaphragmatic hernia, pre-op goals (7)
-Client education and informed consent
-Patient cardiovascular and respiratory stabilisation
-Understanding of the viscera involved in the herniation
-Understanding of any comorbidities or injuries
-Smooth, rapid induction to anaesthesia and establishment of airway access for ventilation
-Thorough understanding of regional anatomy
-Aseptic preparation of the patient
56
Diaphragmatic hernia, surgery goals (5)
- Adherence to Halstead’s principles
- Reduction of herniated tissue and removal of adhesions or damaged tissue
- Anatomic closure of the defect
- Placement of a chest drain and evacuation of the chest sufficiently to allow ventilation
- Abdominal closure without undue tension
57
Diaphragmatic hernia, post op goals.
- Thorough evaluation and control of the patient postoperatively.
- Monitoring and early treatment for any complications.
58
What is the surgical approach of a diaphragmatic hernia repair?
Midline laparotomy from xiphoid to pubis
59
What surgical approach of a diaphragmatic hernia is associated with greater post op morbidity and pain?
Extended into a caudal sternotomy
60
What is ligated to allow greater exposure during Sx of a diaphragmatic hernia?
Falciform ligament
61
What retractor is good for cats in a diaphragmatic hernia repair?
ring retractor
62
Which organs can become congested and friable during hernia repair (2)? Which retractor is advised?
Spleen and liver
Malleable retractor
63
What happens if hernia contents are irreducible?
The hernial ring should be enlarged, avoiding the phrenic vessels, phrenic nerves and caudal vena cava.
64
During intrathoracic adhesions, how should they be broken down if:
A) Mature?
B) Young fibrinous?
A) Sharp dissect
B) Blunt dissect
65
Should rent edges be debrided?
No - iatrogenic trauma, increasing the size of the defect and decreasing the holding power of the sutures.
66
How should tissue margins of recent traumatic hernias be closed?
suture closure should proceed in a dorsal to ventral direction, using an absorbable monofilament synthetic material (e.g. polydiaxanone or polyglyconate) in a continuous pattern. With circumferential tears, the diaphragm can be approximated to the thoracic wall using circumcostal sutures.
67
What is the rare possibility with chronic diaphragmatic hernias which may make cosure difficult?
They may atrophy
68
How can a chronic atrophied diaphragmatic hernia be closed? (2)
Autologous tissue (e.g omentum, muscle, liver, fascia)
Synthetic/natural implants (e.g. mesh, porcine submucosa or silicon rubber tubing).
69
Following diaphragmatic hernia repair, when is an xray indicated? (4)
Concern for:
Pneumothorax
Pleural effusion
Collapsed lung lobes
Chest tube positioning.
70
What should be given intra pleural following hernia repair via thoracostomy tube?
Bupivicaine
71
When can the thoracostomy tube be removed post hernia repair?
No air or less than 2ml/kg/24hr fluid
72
Name hernia repair surgical complications (6)
- Anaesthetic complications
-Haemorrhage
-Visceral injury/strangulation
-Inability to close the hernia rent or abdominal wall in chronic hernias
-Iatrogenic trauma to the phrenic nerves, vessels or caudal vena cava
-Complications arising secondary to resection of adherent viscera
73
Early post op hernia complications (20)
Infection
Pain
Seroma
Haematoma
Tachypnoea
Hypoventilation
Hypoxia
Respiratory acidosis (secondary to pain-associated inadequate ventilation)
Ventilation-perfusion abnormalities
Sudden cardiac arrest
Reperfusion injury
Ascites
Re-expansion pulmonary oedema
Pulmonary oedema
Pneumothorax
Haemothorax
Wound dehiscence and evisceration
Abdominal compartment syndrome
Transient megaoesophagus and oesophagitis
Gastric ulceration
74
Late post op hernia complications (4)
Hernia recurrence
Hiatal hernia
Rupture, strangulation or obstruction of the gastrointestinal tract
Infection of implants
75
How does re perfusion injury occur?
When blood supply returns to hitherto strangulated abdominal organs, releasing toxic by-products of anaerobic metabolism (e.g., unbuffered acids, potassium and lysosomal enzymes).
76
When does re-expansio pulmonary oedema occur?
When atalectic lungs are re-expanded, especially if the atelectasis is chronic.
77
How can re-expanion pulmonary oedema be prevented? (pressures..?) (2)
Do not exceed 15-20 cm H2O and avoiding high airway inflation pressures to evacate the chest of air prior to closure
The pneumothorax alleviated gradually over the following 8-12 hours.
78
When does abdominal compartment syndrome occur?
In patients with chronic hernias secondary to ‘loss of domain’
79
What is the consequences of increased intra-abdominal pressure? (Adbominal compartment syndrome) (6)
Decreased visceral perfusion,
Acidosis,
Decreased renal function,
Decreased cardiac output (leading to hypotension),
Decreased ventilation (leading to hypoxia)
Increased intracranial pressure.
80
How can intra-abdo pressure be performed?
Via indwelling urinary catheter:
81
What to do if intra abdo pressure is 5-10mmHg
Monitor
82
What to do if intra abdo pressure is 11-20mmHg
Medical treatment (analgesia, evacuation of any intraperitoneal or intraluminal contents);
83
What to do if intra abdo pressure is >20mmHg and not responding to medical tx.
Surgical decompression
84
Can can be done surgically to increase abdo space and decrease intra abdo pressure? (5)
Surgical mesh,
Removal of viscera (e.g., splenectomy),
Diaphragmatic advancement
Relating incisions in the external rectus sheath,
A staged closure of the abdomen:
85
How many patients with a diaphragmatic hernia die before presentation?
15%
86
What fails in development with a PPDH?
Transverse septum
87
What herniates in a PPDH?
Herniation of abdo viscera into pericardial sac
88
How can a PPDH be diagnosed? (2)
Xrays
U/S
89
What is seen on xrays with a PPDH? (3)
Enlarged, oval/rounded cardiac silhouette (filled with soft tissue/fat opacity, or gas /faeces-filled bowel)
Dorsally displaced trachea. The diaphragmatic border is discontinuous.
90
Where is an U/S performed to diagnose a PPDH?
Right fifth intercostal space or transabdominally
91
What is the surgical approach for PPDH?
Ventral midline laparotomy (from xiphoid to pubis).
92
How are PPDH small defects closed surgically?
Small defects are closed with a simple continuous pattern of monofilament absorbable material (e.g., polydiaxonone or polyglyconate), beginning dorsally as for traumatic diaphragmatic hernias.
93
IS conservative Tx an option for PPDH?
If assymptomatic
94
In PPDH surgery - what must be done immediately after hernia closure?
Drain pericardial sac
95
What can be done if PPDH defect is large? (2)
What must be avoided?
Flaps
Grafts
- avoid phrenic n.
96
Do patients need a thoracostomy tube following PPDH sx?
most patients do not
97
What is the prognosis for PPDH?
Good, assuming there are no concurrent intracardiac defects.
98
Possible complications of PPDH repair (not seen in traumatic repair). (7)
Hyperthermia
Partial blindness (in cats)
Metaplastic transformation of liver into sarcoma
Refractory pneumothorax
Cough
Constrictive pericarditis
Development of pericardial cysts.
99
Which direction should a radial tear be repaired in?
Dorsal - ventral
100
What suture material for cat radial tear?
3-0 polydioxanone.
