Gen surg Tooics Flashcards
local anaesthetic toxicity
LA toxicity begins with restlessness and progresses to tinnitus, slurred speech, seizures and coma.
Heparin
Prevents activation factors 2,9,10,11
Warfarin
Affects synthesis of factors 2,7,9,10
DIC
Factors 1,2,5,8,11
Liver disease
Factors 1,2,5,7,9,10
Interpretation blood clotting test results
OGD perforation risk
0.01% (diagnostic)
5% (therapeutic). Lower for therapy to benign lesions.
Colonoscopy perforation risk
Colonoscopy
<1 in 1000 if diagnostic
<1 in 500 if therapeutic (polypectomy)
Amount of inguinal hernias that will present as an emergency
Up to 5% of primary inguinal hernias will present with symptoms such as irreducibility or pain and surgery is indicated either during the index admission or soon afterwards depending on the exact situation.
Most radiodense renal stone
Calcium phosphate stones are the most radiodense stones, calcium oxalate stones slightly less so. Uric acid stones are radiolucent (unless they have calcium contained within them).
OGD and anticoagulation
Low risk of bleeding during endoscopy (which include biopsies)=Continue warfarin
Hydro else in clindren
n children a hydrocele is most commonly due to a persistent processus vaginalis. The swelling is intermittent and in most cases that are diagnosed in infancy the hydrocele resolves. Cases that persist beyond two years of age are best managed surgically and the surgical approach is usually made via the inguinal canal where the patent processus is identified and ligated.
Adult hydrogels
Adult hydroceles are less commonly due to the persistence of embryonic remnants and therefore can be managed via a scrotal approach. Both the Lords and Jaboulay procedures are reasonable options.
Submandibular gland surgery
everal nerves are at risk in sub mandibular gland excision. The marginal mandibular and cervical branch of the facial are at risk superficially. During deep dissection the lingual nerve is at risk of injury.
Nerve at risk in parotid surgery
The facial nerve is usually sacrificed in this procedure which is almost exclusively reserved for malignant lesions.
Nerves encountered during surgical procedures
Thyroidectomy - Recurrent and superior laryngeal nerves
Carotid artery surgery -Vagus and hypoglossal nerves
Posterior triangle of neck -Accessory nerve
Submandibular gland surgery Superficial: Marginal mandibular nerve and cervical branch of the facial nerve
Deep: Lingual nerve
Varicose vein surgery- Sural nerve in short saphenous surgery and saphenous nerve in long vein surgery
Thoracic surgery Recurrent laryngeal nerve (particularly left sided)
Approach to brachial artery- Median
Posterior approach to elbow- Ulnar
Anterior approach to hip joint -Femoral
Posterior approach to the hip -Sciatic (and both inferior and superior gluteal nerves)
Pelvic dissection during rectal surgery Hypogastric nerves and nervi erigentes
Asymptomatic hernia strangulation risk
In patients presenting with asymptomatic hernia, the risk of strangulation is approximately 3% per annum.
SOFA scoring
SOFA variables
MAP
GCS
Creatinine
Urine output
Platelet count
Bilirubin
Inotrope use
PiO2/ FiO2 ratio
HIT type 1
Most common
Occurs between days 1 - 5 of therapy
Non immune mediated
Transient drop in platelet count to 100-150 x109
Self limiting, occurs due to heparin binding platelet membranes
HIT type 2
Occurs from day 6 of therapy onwards
Fall in platelet count, usually sustained (towards 50 x 109 or lower)
Immunologically mediated
Necessitates cessation and adjustment of therapy
TPN extravasation
Infiltration of hyaluronidase is specifically indicated for TPN extravasation injuries and should be given within an hour.
Vasoactive drugs extravasation
Inotropes such as dopamine have sometimes been given peripherally (not recommended), when they extravasate they can produce profound tissue ischaemia. Phentolamine is an alpha adrenergic blocker that produces local vasodilatation and helps minimise ischaemia.
DIC factor consumption
DIC Will tend to consume factors five and eight intially (and platelets).
VO2 max and risk of surgery
> 20ml/Kg/ min No increased risk
<15ml/kg/min Increased risk
<10ml/kg/min Very high risk
HIV and deranged LFTe
The most common cause of biliary disease in patients with HIV is sclerosing cholangitis due to infections such as CMV, Cryptosporidium and Microsporidia
Pancreatitis in the context of HIV infection may be secondary to anti-retroviral treatment (especially didanosine) or by opportunistic infections e.g. CMV
Cetuximab
Cetuximab is an EGFR inhibitor, it only works on KRAS wild type tumours, which must be tested for prior to starting therapy.
Mechanism of action of lidocaine
Lignocaine blocks sodium channels. They will typically be activated first, hence the pain some patients experience on administration.
Paediatric splenic injury
Haemodynamic stability and non hilar disruption of the spleen= Non operative management.
90% of all paediatric splenic injuries are managed conservatively.
Case controlled study
A case-control study is a type of study design used widely, often in epidemiology. It is a type of observational study in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute. Case-control studies are often used to identify factors that may contribute to a medical condition by comparing subjects who have that condition/disease (cases) with patients who do not have the condition/disease but are otherwise similar (controls). They require fewer resources but provide less evidence for causal inference than a randomized controlled tria
Cohort study
A cohort study is often undertaken to obtain evidence to try to refute the existence of a suspected association between cause and effect; failure to refute a hypothesis often strengthens confidence in it. Crucially, the cohort is identified before the appearance of the disease under investigation. The study groups follow a group of people who do not have the disease for a period of time and see who develops the disease (new incidence). The cohort cannot therefore be defined as a group of people who already have the disease. Prospective (longitudinal) cohort studies between exposure and disease strongly aid in studying causal associations, though distinguishing true causality usually requires further corroboration from further experimental trials.
Cross sectional studies
Cross-sectional studies involve data collected at a defined time. They are often used to assess the prevalence of acute or chronic conditions, or to answer questions about the causes of disease or the results of medical intervention. They may also be described as censuses. Cross-sectional studies may involve special data collection, including questions about the past, but they often rely on data originally collected for other purposes. They are moderately expensive, and are not suitable for the study of rare diseases. Difficulty in recalling past events may also contribute bias.
Randomised control studies
These studies involve the experimenter allocating a specific exposure or intervention to a group of people who are randomly assigned to a particular group. They may be blinded or non blinded. The method of randomisation and the degree of blinding will have a direct impact on the potential bias of the study. In order to establish the numbers need to enter the study it is usual to perform a power calculation.
Max dose of bupivicaine
150mg
Adrenaline in local
Contraindicated in MAOI (Phenelzine)
Ok with SNRI - venlafaxine
Adrenaline may be added to local anaesthetic drugs. It prolongs the duration of action at the site of injection and permits usage of higher doses (see above). It is contra indicated in patients taking MAOI’s or tricyclic antidepressants.
The toxicity of bupivacaine is related to protein binding and addition of adrenaline to this drug does not permit increases in the total dose of bupivacaine, in contrast to the situation with lignocaine.
Pain reduction with local Anaethetic
Addition of 8.4% sodium bicarbonate will most readily achieve this, typical injection volumes are 2ml per 20ml 1-2% lignocaine.
Primary actions of heparin
Activation of antithrombin III - this inactivates thrombin and factor Xa
Levels of evidence
Levels of evidence
I - evidence from meta-analysis of randomised controlled trials
II - evidence from at least one well designed controlled trial which is not randomised
III - evidence from correlation and comparative studies or use of historical controls
IV - evidence from case series
V - Expert opinion or founded on basic principles
Dabigatran
Competitive direct thrombin inhibitor
Reversed by Idarucizumab
Haemophilia A and surgery
Desmopressin will increase factor VIII levels sixfold and this may suffice for minor surgery (such as a toe nail excision). This should be formally tested on a patient by patient basis in advance.
Procaine
Procaine and benzocaine have amino - ester groups, these are metabolised by pseudocholinesterases.
Chronic Groin Pain in inguinal hernias
10-15%
Chemotherapeutic agents
Kugel type inguinal hernia repair
The Kugel repair is located in the pre peritoneal space, this is the area favored for TEP repairs laparoscopically. Awareness of this technique (which is not widely used) is useful as the unwary surgeon attempting laparoscopic redo hernia surgery may find these challenging recurrences (which occur rarely).
Risk of repeat MI if one recently
