Wednesday, June 29, 2011

CHADS2

CHADS2 score

CCf
Hypt
Age >=75
DM
Stroke (2 points)
(VASc= Vascular disease, Age 65-74, Sex)

(0 aspirin 1 aspirin or warfarin 2 warfarin)

Tuesday, June 28, 2011

epidural abscess

(Sep-2004 Q4) Outline the diagnostic criteria for an epidural abscess

high index of suspicion, may also occur spontaneously without spine/epidural instrumentation

minor
fever- after excluding other causes

procedure: difficult epidural, multiple attempts, no aspetic technique

patient factors: systemic sepsis, DM, immunocompromised

major:
localised back cellulitis
neurological signs- cauda equina, LL weakness, loss of sensation, persistent back pain
MRI findings


Bier's block

August Bier- surgeon 1900s (prilocaine)

now: lidocaine
for surgeries <1 hr

double cuff tourniquet
IV cannula
Esmarch bandage
exsanguinate
inflate distal cuff then proximal cuff then deflate distal cuff
SBP 100mmHg above systolic p
lignocaine through IV cannula (12-15 ml of 2% vs 20ml of 0.5% )

deflate for 10seconds, reinflate 1 min then deflate again

disadvantages:
- tourniquet pain for longer ops
- no post op analgesia

Interscalene

indications:
-shoulder, lateral clavicle, ACJ, proximal humerus
-elbow (low interscalene)
-not good for hand (should use axillary/infraclav)

sitting

complications:
Horner's syndrome
Occurence of ipsilateral ptosis, hyperemia of the conjuctiva, and nasal congestion is common and it is dependent on the site of injection (less common with the low intrascalene approach) and total volume of local anesthetic injected; the patients should be instructed on the occurence of this syndrome and reassured about its benign nature

Phrenic Nerve paralysis (CONFIRMED!)

superficial cervical plexus block

what: anterior primary rami of C2-C4
block will block 4 major branches --antero lateral neck sensory innervation

landmarks: mastoid process-->midpoint (Chassaignac's tubercle of C6 transverse process)-->
branches emerge from posterior border of SCM
fan block and midpoint of the line
depth: superficial only, no more than 1-2cm
shud not have paraesthesia
sensory block only so dilute ok: 0.25% bupivacaine, 10 ml (5 up 5 down)

Monday, June 27, 2011

trauma- neck.subcut emphysema

(May-2001 Q10) A 17 yo trail bike rider was struck on the neck by a low branch and thrown from his bike. He presents to your casualty with a hoarse voice, stridor and subcutaneous emphysema of the neck. Discuss your plan to secure this patient's airway.

This patient has a history of neck trauma and impending respiratory distress. In view of the history of neck trauma and subcutaneous emphysema, the most important differential will be disruption of the tracheobronchial tree.

I would consult an ENT specialist with view of performing a surgical airway, as it is likely that any upper airway manipulation might be difficult in view of localized trauma, and the disruption might be distal to the glottis.

I would discuss with the patient regarding an awake tracheostomy under local anaesthesia. This would be done with supplemental O2 via facemask and standard college monitoring is in place.This may not be tolerated well by the patient, however sedation may be fraught with danger because he might have respiratory depression that would further compromise the airway.

maintain spont vent

Alternatives would be fibre optic assessment of the trachea but this is not ideal in this situation given that the patient is stridorous and less likely to cooperate with the procedure. Also, any trauma or bleeding from fibre optic intubation may further jeopardise the airway.

any ETT should be cuffed passed distal to the disruption

Tracheostomy -may be able to locate the distal end of the disruption but may still be proximal to the tracheobronchial disruption , may be difficult due to local tissue injury/bleeding/ edema, may not be aseptic.

After securing the airway, secondary survey looking for other causes of subcut emphysema/ other areas of injury

definitive imaging: neck XR/CT thorax

novoseven Control trial

Results of the CONTROL Trial: Efficacy and Safety of Recombinant Activated Factor VII in the Management of Refractory Traumatic Hemorrhage

C Hauser et al. J Trauma. Sept 2010: 69(3); 489-500


481 blunt and 92 penetrating) who bled 4 to 8 red blood cell (RBC) units Patients were assigned to rFVIIa (200 μg/kg initially; 100 μg/kg at 1 hour and 3 hours

Results: Enrollment was terminated at 573 of 1502 planned patients because of unexpected low mortality prompted by futility analysis (10.8% vs. 27.5% planned/predicted) and difficulties consenting and enrolling sicker patients. Mortality was 11.0% (rFVIIa) versus 10.7% (placebo) (p = 0.93, blunt) and 18.2% (rFVIIa) versus 13.2% (placebo) (p = 0.40, penetrating). Blunt trauma rFVIIa patients received (mean ± SD) 7.8 ± 10.6 RBC units and 19.0 ± 27.1 total allogeneic units through 48 hours, and placebo patients received 9.1 ± 11.3 RBC units (p = 0.04) and 23.5 ± 28.0 total allogeneic units (p = 0.04). Thrombotic adverse events were similar across study cohorts.

Conclusions: rFVIIa reduced blood product use but did not affect mortality compared with placebo. Modern evidence-based trauma lowers mortality, paradoxically making outcomes studies increasingly difficult.

Sunday, June 26, 2011

paeds dental

(May-2008 Q11) You are the anaesthetist at a childrens' hospital. A 3yo schedules for dental restoration and extractions is found to have a systolic murmur during your preoperative assessment on the day of surgery. They have been on a waiting list for 6 months and have had a dental abscess that settled with antibiotics. Describe how you would evaluate the significance of this murmur and how this decision would affect your decision to proceed or not with surgery.

Evaluate

I would evaluate the significance of the murmur with history, physical examination and investigations.
I will speak to the parents regarding the child's antenatal and developmental history, specifically asking for any diagnosis of pre-existing syndromes or abnormalities that could include congenital heart disease.

I will ask about any recent change in health especially failure to thrive, developmental delay, symptoms of heart failure such as decreased effort tolerance, dyspnea , wheezing, cyanosis. Recent fever that could accompany SBE, medication history and course of abx for dental abscess

medical records of previous examination/admissions

Examination: Thorough cardiovascular examination, development/ general inspection
clubbing/ cyanosis,
nature of the murmur: if it is fixed, not related to movement/respiration-unlikely to be a flow murmur
pulse oximetry

investigations: if my history/examination is suggestive of IE, given that the child had a dental abscess and may have infective endocarditis/valve disease secondary to IE, refer to a paediatric cardiologist, to 12 lead ECG, CXR, 2DEcho
FBC: anaemia, TW, CRP

Decision
-multidisciplinary: consult cardiologist, dentist (children's hospital, proximity of paeds cardiologist available)
-discuss with parents
-if child is well thrived, not symptomatic, -unlikely IE minor surgery-proceed
-relative urgency of surgery: postponed 6 months, ago, may be a constant focus of infection and source of bacterial seeding, already had complications (abscess requiring abx), stress of cancellation on staff and family,
-give antibiotic prophylaxis of IV ampicillin 50mg/kg before procedure (if pathological murmur; not indicated for innocent murmur)
-admit post op for observation and investigations

if suspected IE: sympathetic discussion with family, consult cardiologist, alter list to allow time for investigations


exam report:
Hx, examination, integration of info to form decision
3 year old: commonest age for innocent murmur
-acknowledge; high risk of bacterial seeding with procedure
-reference to 2decho, IE prophylaxis (NICE and AHA guidelines)
(Sep-2004 Q13) Describe the technique of applying cricoid pressure to prevent regurgitation of gastric contents.

Cricoid pressure is a manouvere done to occlude the upper esophagus by pressure at the cricoid cartilage, which is a complete ring of cartilage caudal to the most prominent cartilage (the thyroid cartilage), against the c5 vertebral body. The cartilage is fixed with the first and second digits and with the application of directly backward with a force of 30N

more evidence needed! ___

trauma novoseven

http://www.trauma.org/index.php/main/article/367/print

Thursday, June 23, 2011

severe preeclampsia

(Oct-2008 Q8) A 25yo primigravida patient presents to the delivery suite at 38 weeks gestation complaining of a headache and difficulty with her vision. Her BP is 180/115 and she has clonus. CTG monitoring shows no indications of foetal distress. Outline your initial management of her pre-eclampsia

This term pregnant patient has severe pre-eclampsia (definition)and has signs of impending ecclampsia, which is a life-threatening condition. After a focused history and examination I would arrange for urgent lab investigations especially looking at the renal panel, PT/PTT , liver enzymes, Mg and FBC for platelet count.

My initial management wound be to stabilize the patient and discuss with her obstetrician …(multidisciplinary )and arrange for expedient delivery of the child.

In the mean time I will give her supplemental O2 and place her in a left lateral tilt to reduce aortocaval compression in this situation where there is already compromised blood supply to the fetus. Standard monitoring in addition: BP on both arms, urine output

I would start IV magnesium as a slow bolus (loading dose___) followed by an infusion of ____ to achieve serum Mg level of 2-4mmol/L

I would also lower the blood pressure by starting IV labetalol as an infusion 10-50mg/hour, avoiding precipitous falls in BP and targeting a BP of 140-150/100-110

Fluid resus; regional if no contraindications, post op HD +/- CVP

Severe hypertension: BP 160/110

Wednesday, June 22, 2011

reimplanted limb

(May-2007 Q14) An otherwise fit 30 yr old man is having microvascular reimplantation of his forearm. Describe methods available to optimise the perfusion of the perfusion of the reimplanted limb in the post-operative period.

Pharmacological and non pharmacological

Pharmacological :

1) regional anaesthesia induced sympatholysis and vasodilation of upper limb arterioles

2) dextran: polysaccharide, inhibits , promotes microvascular blood flow

Non pharmacological

1) keeping reimplanted limb warm

2) ensuring adequate hydration to avoid increased vasoconstriction and SVR

3) avoiding compartment syndrome, keeping replanted limb elevated

4) optimal Hb

5) appropriate monitoring of BP

6) monitoring of limb, early management of ischaemia

7) ?optimising venous pressure?

Although the question asked for management in the post operative period, no candidate was marked down for discussion involving intra-operative factors affecting post operative management.


Sunday, June 19, 2011

radial art cannulation

(May-2008 Q2) Why is the radial artery a common site for arterial cannulation? What complications may occur from radial artery cannulation and how may they be minimised?

The radial artery is a common site for cannulation because it is superficial and easy to assess, distal and therefore allows more proximal arteries to be left intact in case of failing to cannulate distally, the proximal brachial artery is still available as an alternative (although this is not ideal).

It is compressible and therefore in the case of a hematoma, expansion of the hematoma may be limited by direct pressure

Clean, correlates well with BP, collateral circulation, discrete from nerves

Complications:

1) hematoma

2) thrombosis/ vasospasm/air bubbles leading to distal ischaemia

- minimized if pre cannulation allen’s test is done to ensure presence of collateral circulation to the hands prior to radial art cannulation

3) infection- this may be minimized by using an aseptic technique, vigilance for infection/ cellulitis and prompt removal of the cannula, changing the site of the cannula every week (?evidence?) strict asepsis when obtaining blood samples from cannula

4) Invasive arterial cannulation only when indicated : >4 ABG /day, hemodynamic monitoring crucial

5) Drug injection- adequate labelling, staff training, prompt recognition if drug has been given to do corrective measures

aspiration

(May-2006 Q1) List the predisposing factors for aspiration of gastric contents in a patient undergoing general anaesthesia. Discuss the measures you would take to prevent this complication.

Predisposing factors :

1) patient factors

- GERD

- Pregnancy

- inadequate fasting : 8 hours or more for fatty food, 6 hours for milk or solids, 2 hours clear feeds, 3-4 hours for breast milk in <4 month old infants

- type of food

- medications that slow gastric emptying: opioids

- distracting injuries: trauma

- GI stasis: I/O

2) surgical factors

- laparoscopic surgery

3) anaesthesia factors

- use of a supraglottic device

- gastric insufflation with BV ventilation

- no RSI

altered consciousness/ severe TBI (GCS),

loss of laryngeal reflexes eg stroke/ Parkinson’s

difficult airway

pre op

prevent aspiration

-await gastric emptying if possible

reducing morbidity from aspiration: with reducing volume and acidity : adequate fasting , prokinetics, PPI or antacids/ H2 antagonists

inducing with head up position/shoulder roll/ avoid BVM , intubate with RSI, inflate cuff appropriately

ryles tube to reduce gastric contents

extubate awake

Lower limb block anatomy

http://web.squ.edu.om/med-Lib/MED_CD/E_CDs/anesthesia/site/content/figures/2007F21.gif

virtual anaesthesia machine

http://vam.anest.ufl.edu/


Thursday, June 16, 2011

ESRA anticoagulation guidelines

http://www.esra-learning.com/site/generalites/anticoagulation/b_anticoagulation.htm





unfractionated heparin



during low-dose administration of unfractionated heparins, an interval of 4 hours should be observed between heparin administration (usually 5000 IU s.c.) and epidural puncture or catheter removal, in order to avoid bleeding complications. Any repeat administration of low-dose heparin should then follow at the earliest after 1 hour.



risk of haemorrhage after epidural anaesthesia and subsequent heparinization is not increased if the heparinization is carried out at the earliest 1 hour after spinal/epidural puncture and is closely monitored. (and no concurrent antiplatelets)





LMW Heparin



The advantages-high level of bioavailability (ca. 100%) after sc administration and their long half-life of 4–7 hours. Max effect 4hrs post admin


-gold standard for thromboembolism prophylaxis in high-risk patients


-no difference in clinical efficacy has yet been demonstrated between the individual preparations. low risk of HIT but should not be used in patients with HIT



Aspirin


The safety of neuraxial regional anaesthesia in patients receiving acetylsalicylic acid is mainly based on three studies [40–42]. Although the Collaborative Low-dose Aspirin Study in Pregnancy (CLASP)




Wednesday, June 15, 2011

AKI and RIFLE

http://www.medscape.com/viewarticle/533563

Acute kidney injury occurred in 67% of intensive care unit admissions, with maximum RIFLE class R, class I and class F in 12%, 27% and 28%, respectively. Of the 1,510 patients (28%) that reached a level of risk, 840 (56%) progressed. Patients with maximum RIFLE class R, class I and class F had hospital mortality rates of 8.8%, 11.4% and 26.3%, respectively, compared with 5.5% for patients without acute kidney injury. Additionally, acute kidney injury (hazard ratio, 1.7; 95% confidence interval, 1.28-2.13; P < 0.001) and maximum RIFLE class I (hazard ratio, 1.4; 95% confidence interval, 1.02-1.88; P = 0.037) and class F (hazard ratio, 2.7; 95% confidence interval, 2.03-3.55; P < 0.001) were associated with hospital mortality after adjusting for multiple covariates.Conclusion: In this general intensive care unit population, acute kidney 'risk, injury, failure', as defined by the newly developed RIFLE classification, is associated with increased hospital mortality and resource use. Patients with RIFLE class R are indeed at high risk of progression to class I or class F. Patients with RIFLE class I or class F incur a significantly increased length of stay and an increased risk of inhospital mortality compared with those who do not progress past class R or those who never develop acute kidney injury, even after adjusting for baseline severity of illness, case mix, race, gender and age.

LA toxicity

(Sep-2003 Q7) At the end of an open cholecystectomy, intercostal nerve blocks with a total of 20ml bupivacaine 0.5% are placed at two levels while the patient is still under general endotracheal anaesthesia. The patient develops ventricular fibrillation within 3 minutes. Describe your management of this situation.

The patient has received 20x5mg =100mg of bupivacaine and the weight of the patient is not known here but given the short duration prior to cardiac arrest, the most likely differential in this situation is cardiovascular collapse from LA toxicity. Other less likely differentials would be a acute coronary event due to underlying ischaemic heart disease or arrhythmias.
The immediate management of this patient will include resuscitation according to BCLS protocols while maintaining the airway and breathing by leaving the patient intubated, 100% O2 and commencing CPR and defibrillation. IV adrenaline boluses 1mg of 100mcg/ml dilution and magnesium may be given. ?phenytoin.

Lipofundin as been shown to be effective in ???? it is available as given via a large bore IV line as a rapid bolus of 100ml followed by 400ml

The surgical team and family has to be informed and the patient admitted to SICU after successful resuscitatoin. ? maintainence lipofundin?Incident reporting and post event counselling.

Tuesday, June 14, 2011

Fat embolism syndrome

(May-2008 Q4) Describe the clinical features and treatment of Fat Embolism Syndrome.

Clinical features:
1) hemodynamic changes: tachycardia, hypotension, desaturation
2) ECG changes: right heart strain , RV failure
3) End tidal CO2 : marked reduction due to reduced preload and cardiac output
4) Clinical: confusion, dyspnea, petechiae

Treatment:
1) initial stabilisation, 100%O2, diuretics ventilatory support and endotracheal intubation if necessary
2) CVP, aspiration of embolus ??
3) Monitoring for complications eg ARDS, DIVC
4) Arterial blood gas and 12 lead ECG
5) early fracture fixation
6) controversial: heparinisation, corticosteroids


Marks for situations where FES is likely to occur

Diagnostic criteria (combined from various sources)
Diagnostic criteria were first devised by Gurd and have been modified several times since.8,9
Major criteria
• Respiratory insufficiency
• Cerebral involvement
• Petechial rash
Minor criteria
• Tachycardia
• Pyrexia (usually >39°C)
• Confusion
• Sustained pO2 <8 kPa • Sustained respiratory rate >35/minute, in spite of sedation
• Retinal changes - cotton wool exudates and small haemorrhages, occasionally fat globules seen in retinal vessels
• Jaundice
• Renal signs
• Thrombocytopenia
• Anaemia
• High ESR
• Fat macroglobulinemia
• Diffuse alveolar infiltrates 'snow storm appearance' on chest X-ray


Causes
• Fractures - closed fractures produce more emboli than open fractures. Long bones, pelvis and ribs cause more emboli. Sternum and clavicle furnish less. Multiple fractures produce more emboli
• Orthopaedic procedures - most commonly intramedullary nailing of the long bones, hip or knee replacements4
• Massive soft tissue injury
• Severe burns
• Bone marrow biopsy
• Nontraumatic settings occasionally lead to fat embolism. These include conditions associated with:
o Liposuction5
o Fatty liver
o Prolonged corticosteroid therapy
o Acute pancreatitis
o Osteomyelitis
o Conditions causing bone infarcts, especially sickle cell disease



Presentation
There is usually a latent period of 24 to 72 hours between injury and onset. The onset is then sudden, with:
• Breathlessness ± vague pains in the chest. Depending on severity this can progress to respiratory failure with tachypnoea, increasing breathlessness and hypoxia.
• Fever - often in excess of 38.3°C with a disproportionately high pulse rate.
• Petechial rash -commonly over the upper anterior part of the trunk, arm and neck, buccal mucosa and conjunctivae. The rash may be transient, disappearing after 24 hours.
• Central nervous system symptoms, varying from a mild headache to significant cerebral dysfunction (restlessness, disorientation, confusion, seizures, stupor or coma).
• Renal - oliguria, haematuria, anuria.
• Drowsiness with oliguria is almost pathognomonic.


Predictors of fat embolism
- long bone fractures (excluding NOF)
- multiple fractures

anaesthesia for laryngectomy

http://books.google.com/books?id=qCN6PfjWWmwC&pg=PA370&lpg=PA370&dq=laryngectomy+anaesthesia&source=bl&ots=O3qHGmG9e-&sig=q49dguzy_8KaUOhFPi4ehdd-3nw&hl=en&ei=Y2H3TZTuC4uyrAe19ZmuCA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBkQ6AEwAA#v=onepage&q=laryngectomy%20anaesthesia&f=false

Monday, June 13, 2011

opioids and opioid dependence

A 34 year old, opioid-dependant woman is complaining of severe pain on the day after a first metatarsal osteotomy. The nurses are concerned she is drug-seeking. a. How would you assess this patient? (60%) b. Outline your pain management plan. (40%)(May 2010- Q-11)


1). history
- baseline usage of opioids , dose and route (PO or IV)
- last intake of opioids
-nature of the pain- consistent with surgical site? Nociceptive pain?

2)clinical notes: amount of analgesia given and response to analgesia , any missed doses

3) thorough physical and psychological assessment: vital signs, symptoms of withdrawal


b. Issues of acute pain and chronic dependence, which may also be related to opioid tolerance. Larger doses than expected may be required to treat acute nociceptive pain

Multimodal analgesia involving a multidisciplinary team

long acting opioids should be given to maintain baseline requirements and avoid opioid withdrawal.
alternatives to opioids would be non opioid analgesics such as paracetamol and NSAIDS, which should be given strictly round the clock
give fast acting, long acting opioids eg oxynorm for breakthrough pain

opioid sparing techniques include splinting, ankle blocks etc.

I would avoid giving IM pethidine or other short acting opioids

refer to psychiatry for counselling

regular monitoring
establishing boundaries

commonest drugs of abuse?

laser

(May-2008 Q9) A 25 yo man is to have laser surgery for a vocal cord papilloma. What are the hazards associated with the use of laser in this situation and how can they be minimsed?

Laser defined as: Light Amplification by Stimulated Emission of Radiation
Hazards of use are mainly related to airway fire due to ignition by heat generated from the laser beam.

It can be minimized by surgical preparation and anaesthesia factors
Surgical preparation: use laser in short bursts

Sterile water for irrigation should always be available.
OT preparation
In the event of an airway fire, irrigation with saline or sterile water

Anaesthesia factors: use as low an FiO2 as possible (as low an oxygen concentration to maintain adequate oxygenation)
Vigilance
Use of ETT with ? wire/armoured tube


Laser may cause airway papillomas?

LASER officers, fire drill

types of laser: CO2, Yag, ?

Apgar score

recurrent laryngeal nerve function

(Sep-2003 Q13) How can recurrent laryngeal nerve function be assessed in the postoperative period?

RLN function can be assessed via invasive and non-invasive means

invasive test: nasoendoscopy to see weakness of unilateral glottis- inability to abduct? (remains adducted)

EMG?

non invasive: -clinical tests: presence of a leak if the patient is intubated and if the cuff is allowed to deflate, presence of stridor

RLN function can be monitored intra-op : conventional: needle electrode into cricoarytenoid. New: endoscopic visualisation (eg LMA)



The RLN (branch of the Vagus) is a mixed motor, sensory and autonomous nerve thatinnervates all intrinsic muscles of the larynx with the exceptionof the cricothyroid muscle, which is innervated by the superiorlaryngeal nerve.
ops at risk: thyroidectomy (<5%)/ACDF, carotid endarterectomy

http://www.omjournal.org/images/59_M_Deatials_Pdf_.pdf retrospective review

good review article

Sunday, June 12, 2011

LMA in dental surgery

(Sep-2004 Q10) Justify the use of a laryngeal mask airway in a 25 yo, 80kg man having general anaesthesia for removal of 4 molar teeth.


Anaesthetic indications:
Use of a LMA in this case is less invasive than endotracheal intubation. As this surgery is most likely in the setting of ambulatory surgery, this reduces the need of muscle relaxation, reduces morbidity from sorethroat, especially if the patient is obese and is potentially difficult to intubate. The option of a flexible LMA also allows the tube to be manipulated away from the side of surgery.

Provided that the adequacy of spontaneous ventilation can be achieved to maintain adequate depth of anaesthesia.

The surgeon also has to be agreeable to the use of a supragottic device and is vigilant about suctioning of wash and secretions.

supraglottic devices, if used with adequate depth of anaesthesia, causes a lower risk of laryngospasm.

increased turnover time
easier to insert,

contraindications to LMA: patient with reflux.
disadvantages: less secure airway-may dislodge or kink, shared airway and limited access, secretions, leak with higher airway pressures (esp if obese)

intralipid/ lipid rescue

use in LA toxicity with cardiac arrest especially bupivacaine (CC:CNS ratio?)
functions as a 'lipid sink' for lipophilic agents


resus according to BCLS protocols-lipid rescue-post op icu monitoring

Contents:
Purified soybean oil 200 g
Purified egg phospholipids 12 g
Glycerol anhydrous 22 g
Water for injection q.s. ad 1000 mL
pH is adjusted with sodium hydroxide to approximately pH 8.
Energy content/L: 8.4 MJ (2 000 kcal).
Osmolality (approx.): 350 mOsm/kg water. 500ml bottle: first 100ml over 15 min then 400ml over

protocol:.5ml/kg as initial bolus, then 0.25ml/kg/min for 30-60 mins
In actual resuscitation for a 70kg person: 100ml as bolus then 400ml over the next 15mins

http://www.lipidrescue.org/

TOW the blocks

neuraxial

peripheral

truncal: paravertebral
superficial and deep cervical plexus
brachial plexus
upper limb nerves
wrist block

lumbar plexus
femoral nerve
sciatic nerve-popliteal
ankle block

Wednesday, June 8, 2011

Australian resus council

http://www.resus.org.au/

myasthenia gravis

tutorial today by Dr Hari - question was apparently asked in oct 2009

you are an anaesthetist in a rural hospital and the obstetrician calls you regarding an emergency CS for NRFS. She also has a past history of myasthenia gravis

1) how do you go about determining the degree of NRFS
-use of CTG - presence of late or variable decelerations, defined as decrease in HR of more than 15 beats lasting at least 30 s
-use of scalp pH (normal pH of neonate 7.25-7.35), so fetal distress is when scalp pH <7.25

2) how do you go about assessing this patient for op
don't just focus on the obstetric history- placenta praevia, antenatal history, GDM, lie etc, gestation
-history
-clinical exam
-go through relevant investigations
-old notes

history: extent of disease, control, recent exacerbations esp due to pregnancy
medications: pyridostigmine dose, steroids, immunosuppressants, plasmapheresis
autonomic instability
pre op PFT


issues of post op ventilation:

management: pre op aspiration prophylaxis, neonatologist, wedge , warm OT for baby
standard monitoring, airway trolley and difficult airway adjuncts, experienced surgeon, colleague to help with anaesthesia, AU
working IV plug
maintain with 02:n2o:inhalational, use bis to reduce amount of inhalational (potentiate nm weakness), nerve stimulator

pharmaco: duration of action of sux : unpredictable, may require higher dose eg 2mgkg
high dose may cause type 2 blockade, onset delayed
if on regular plasmapheresis, enzyme to metabolise sux may be reduced
increased sensitivity to relaxant

if not given usual meds preop: controversial- give IV neostigmne 1:30mg pyrido or NG pyrido?
non depolarising: give 1/10 of usual dose, titrate to nerve stimulator

  • Ensure that the patient is reminded prior to induction of the possibility of a prolonged intubation*

Extubation: performed on awake patients and hopefully close to his/her baseline status. Reinstitute anticholinesterase medication, either by IV infusion or by reimplementation of the patient's oral regimen.

Leventhal criteria: Predictive scoring system for the need for postoperative ventilation

1) duration of disease for 6 years or longer

2) chronic comorbid pulmonary disease

3) pyridostigmine dose >750 mg/d

4) VC <2.9L

5) Other indicators include preoperative use of steroids, and previous episode of respiratory failure.

These predictors have not been widely validated. (1)

Drugs to avoid: Calcium Channel blockers, Magnesium, Aminoglycoside antibiotics as all of these may contribute to muscle weakness

Post-Op Bed: Patients should be monitored in either a ICU or step-down unit but NOT to a conventional surgical ward.


3) MG vs eaton lambert,

tensilon to differentiate


4) baby not breathing , mother not stable

priority is to stabilise mother

baby: SpO2 88% Hr 50, chin lift and BVM (? pressure gauge), towel under shoulders. intubate , start CPR

CVS collapse most likely due to hypoxia

call code blue, adrenaline 10mcg/kg

stop CPR when HR >60

ETT adrenaline 100mcg/kg (other routes IM, umbilical)

resus guidelines :ARC


5) PPH: anaes plan
-defined as? >500ml/24h
-fluid resus
-post partum : assum gastric physiology and aspiration risk still present up to 48h
-issues of recent GA, physiology changes, MG

anzca anaes viva

definite to get 1 obs/paeds/trauma case, +/- pain and 3 others

Tuesday, June 7, 2011

TOW spine

T7 decompression, T5-T9 fusion and instrumentation

for HCC and spine mets with cauda equina syndrome- relatively urgent op, 69 year old

Induction as per normal
log roll to special ot table , foam pillow for face. Eyes padded to delineate boundaries of orbit. Visible through mirror facing the face

IA line coz history of AF .
Hb maintained >10
atracurium infusion via tracium pump 10mg/hr, desflurane

Monday, June 6, 2011

TOW Apfel score for PONV

4 risk factors of PONV
- female,
-non smoker
-h/o PONV/motion sickness
-post op opioid use

2 risk factors: 1
3 risk factors or more: 2 antiemetic
4 risk factors: consider changing anaesthetic : TIVA/ RA?

http://www.aafp.org/afp/2007/0515/p1537.html#afp20070515p1537-t1

Thursday, June 2, 2011

TIVA for spine op

anterior cervical discectomy and fusion for 2 levels with neurophysio monitoring

85kg young man

supine, arms tucked in, long extensions, warmer, BIS
induction as per normal ( armoured tube minus stylet, rocuronium and fentanyl)
armoured tube: NG for op, bite block, IDC. op about 3-4 hours
TIVA propofol bristol model 10-8-6 maintained at about 5-6mg/kg/hr (about 510mg/hr!!)
BIS 40-55
morphine 6mg at the end
*no nitrous or benzos but used remifentanyl 0.1mcg/kg/min
post op cervical collar

ps. usually no MEP/SSEP monitoring

bristol model

propofol 10-8-6mg/kg/HOUR
10mg/kg/h for 10 min, 8mg/kg/h for 10 min, 6mg/kg/h
note: n20 used


Wednesday, June 1, 2011

TOW cell saver

http://ccforum.com/content/8/s2/s53

AIMS anaesthesia analysis

http://www.apsf.com.au/crisis_management/crisisframe1_frame1.htm

THE BASIC ALGORITHM
commit to memory
C Circulation Capnograph Colour (Saturation)
O Oxygen Supply Oxygen Analyser
V Ventilation (Ventilated Pts) Vaporisers
E Endotracheal Tube Eliminate Machine
R Review Monitors Review Equipment

A Airway (if Face mask or LMA)B BreathingC Circulation (in more detail)D Drugs

A Awareness Air embolism Air in pleura Anaphylaxis

SWIFT CHECK of Patient, Surgeon and Surrounds

Change order for spontaneous breathing to:AB COVER CD A SWIFT_CHECK

Oxford league table

http://www.medicine.ox.ac.uk/bandolier/booth/painpag/Acutrev/Analgesics/Leagtab.html