Misc Flashcards
What are the stages of renal failure
Stage 1 - creatinine 1.5 to 1.9 times baseline Stage 2 - between 2 - 2.9 times Stage 3 - >3 times or creatinine >400 or initiation of RRT
How does Loperamide work?
Invitro and animal stusides show that loperamide works by:
- It binds to the opiate receptors in bowel wall and prevents acetylcholine and prostaglandin release thereby slowing down peristalsis. This increases intestinal transit time and allows resorption of fluid from the luminal contents thereby making them more solid.
- It also increases resting anal tone thereby reducing incontinence and urgency
How do you classify burns depth?
What factors drive tissue edema
Ocotic pressure gradient (or colloid osmotic pressure) - generated by proteins (draws fluid into veins)
Hydrostatic pressure gradient (pushes fluid out at arterial capillary end)
Where are small bowel diverticulae located? which part of intestine is it most common in? What are the presenting symptoms and management?
They are false diverticuale located in the anitmesenteric border (c.f. meckels). Most common in duodenum>jej>ileum (2-5% of patients)
Usually asymptomatic and does not need any treatment. but can present with:
abdo pain
bleeding
obstruction
Intussuscpetion
perforation
bacterial overgrowth
Treatment is directed by symptoms
How can you differentiate jejunum from ileum intraop?
JEJUNUM
- proximal 2/5th
- thicker wall
- wider bore
- longer vascular arcades
ILEUM
- distal 3/5th
- thinner wall
- narrower
- shorter, more dense arcades
Management of Meckels
Asymptomatic and found on imaging > no surgery. Average lifetime risk of complications 5%. Chance of death even less. on avg, 800 patients will need surgery to save 1 life if these are operated on.
Asymptomatic found intra-op
- <18yrs - resection and anastamosis
-
adults
- palpable abnormality - resect
- no palpable abnormaltiy - leave
symptomatic - resect
segmental resection with 1 cm margin nd anastamosis.
Diverticulectomy is an option if no palpable tissue at base, neck <2cm wide and diverticulum is not short and wide.
describe the pathogenesis of inguinal hernias
teh pathogenesis of inguinal hernia is multifactorial:
- Persistence of patent processus vaginalis. However post mortem studies show that up to 30% of patients with a patent PV do not have an inguinal hernia
- collagen disorder - henrnias in general develop in patients with a low ratio of collagen 1 : 3.
Picture of the structures encountered during lap hernia
Picture of the nerves around inguinal canal
Relevant nerves are
Iliohypogastric (lower abdo wall) -
Ilioinguinal (scroutm/labia)
lateral femoral cutaneous (lat thigh)
femoral branch of GF nerve (lat thigh)
Genital branch of GF (scrotum/labIA)
what proportion of patients develop post hernia pain? What are risk factors and how can you reduce the incidence
Post hernia repair pain is reported in up to 40% of patients. However most of these settle within 3 months. the incidence of ongoing severe pain after 3 months is approximately 2-3 %.
Phases of pain -
- Inflammatory pain - initial pain due to inflammation (throbbing). should settle within 2 months in abscense of a cause.
- Neuropathic pain - due to nerve injury/ entrapment/abnmormal neuroma development - persists beyond 3 months.
Risk factors
- young age
- Female gender
- Pre-op pain
- Severe post op pain
- History of chronic pain
- post op complication
- re-do surgery
- Anterior hernia repair
Risk reduction
- use of abssorvable sutures to secure mesh
- use of fibrin glue (tissseal) inseatd of tacks or sutures
How would you manage post hernia pain?
I would investigate any patient who has persistent pain beyond 8 weeks. If no underlying cause seen then neuropathic pain is diagnosed after 3 months from surgery.
Investigation - MRI to look for mesh migration/ collection/ hernia recurrence or adductor tendinitis.
Treatment
- simple analgesia
-
referral to pain team for
- Nerve block - can be repeated weekly in an attempt to break the pain cycle.
- Medical neurolysis - with phenol
-
Surgical
- Trippple neurectomy and mesh explantation with new mesh implant (success rate in treating pain 75-90%). Iliohypogastric, ilioinguinal and genitofemoral nerves excised. Selective neurectomy may be performed if previous nerve block has identified a specific culprit nerve
What is abdominal compartment syndrome? What are the causes?
New organ dysfunction in presence of raised intra-abdominal pressure (>20mmHg) (note for extremity compartment syndrome, a difference of 30mmhg between diastolic and compartment pressure is used)
Causes
Burns
trauma
vascualr surgery
peritonitis
Severe SIRS with third spacing
major surgery
What knock on effect does abdominal compartment syndrome have?
Cardiovascular
- decreased cardiac output due to decresed venous return
- direct pressure on heart
Resp
- hypoxia and fatugue in spont breathing patient
- barotrauma in ventillated patients due to incresed airway pressure
Kidney
- acute kidney injury and decresed urine output due to
- compression of renal vein
- renal artery constriction due to decrease cardiac output
CNS
- decreased cerebral perfusion pressure due to increased ICP due to increased abdo pressure
GI tract
- mesenteric vasoconstriction
Treatment for Abdominal compartment syndrome
Treat if new organ dysfunction and IAP>20mmhg
LUMINAL drainage
- NG
- flatus tube
- IDC
Extra Luminal drainage
- paracentesis
- drain large retroperitoneal collection
- drain large intra-abdominal fluid collections
Medical
- Aanalgesia
- Muscle relaxants and paralysis with intubation
- Change to pressure control mode on ventillator
- Reduce fluid overload
- Manage in supine position
Surgical
- decompressive laparotomy with temporary closure
What is coeliac diasease? how is it diagnosed? what are the differentials?
Coeliac dis is an autoimmune disorder affecting the small bowel and triggered by gluten. It is charcaterised by mucosal inflammation, villous atrophy and crypt hyperplasia.
Diagnosis is by coeliac antibodies (anti gliadin and anti tTG IGA) and multiple duodenal biopsy.
Differentials:
- tropical sprue
- IBD
- radiation enteritis
- viral eneteritis
causes of splenomegaly
What are PaO2/Fio2 ratios and A-a gradient?
Pao2/Fio2- ratio is used to diagnose ards and is an important paratmeter for assesing presence of organ failure. Pa02 is Partial pressure of in arterial blood.
Normal ratio = 400 -500
<300 mild failure
<200 moderate
<100 severe
PaO2 obtained from blood gas. e.g in normal young adult fio2 = .21 Hence PaO2 should be .21x500 = 105 mm Hg.
Fi02 estimation - RA = 20%, 2L = 25, 4L = 30, 8L = 40, 12L = 50
A-a gradient stands for differencebetween partial pressure of O2 in alveoli - artery. PAO2 (alveolar) is calculated from alveolar gas equation but it is usually 4+age/4 more than Pa02. Hence for 40 yr old it should be 4+10=14 more than PaO2.
A-a grad is increased in V/Q mismatch, ARDS, pneumonia. Hyper or hypoventillation can be assessed by low or high PaCo2 since co2 diffuses across alveoli very easily. hence low PaCo2
coagulation cascade with blocking points for important drugs
How do you interpret TEG
