Sunday, January 1, 2012

myotonic dystrophy

myotonic dystrophy

type 1: congenital/childhood/adult/late

type 2: prox myotonic dys/myo/myopathy syndrome

type 1: unstable trinucleotide expansion
adult onset= autosomal dominant
premature balding, muscle degeneration, cataracts, diabetes mellitus, gonadal atrophy, cardiac abnormalities, adrenal insufficiency, cardiac abnormalities

cardiac- AV delay, atrial tachydysrhythmias, diastolic dysfunction, MVP, cardiomyopathy, sudden death

restrictive lung disease, mild hypoxemia
may have respiratory muscle myotonia-- dyspnea-treat w procainamide
alteration of smooth musc function-gastric atony, intestinal hypomotility

aspiration risk from pharyngeal muscle weakness
pregnancy: may ppt CCF, may need CS for uterine atony
infants of mothers with myotonia-- may develop congenital myotonic dystrophy

Rx: supportive / preventive
sodium channel blockers: less conclusive results

Anaes:
sux : exaggerated contracture-- avoid
chronic myopathy: response to ND NMBA may be exaggerated
muscle stimulation with nerve stimulator: may trigger myotonia
neostigmine: may trigger myotonia
sensitive to respiratory depressant effects


ECT

remote

procedure- pulsed 60 Hz, pulse duration 0.75 ms, total stimulus 1.25s
tonic phase lasting 20s then clonic phase

CVS: parasympathetic stimulation (10-15s) followed by sympathetic : hypertension, dysrhthmias (lasting >=5 min)

CNS: increased CBF, CMRO2, ICP

others: increased IOP and IGP

contraindications- recent AMI, CVA (,3mths) raised ICP, unstable C spine, intracranial mass, aortic aneurysm.
relative:CCF, severe pulm dz, glaucoma, retinal detachment, VTE, thrombophlebitis, angina pectoris


agents : if previous ECTs done, check dosing and adequacy of seizure and adjust accordingly
most preferred=methohexitone (no effect on duration) or propofol (shortens duration of seizure) etomidate: does not shorten seizure duration.

sux 0.5mg/kg or mivacurium 0.08mg/kg

atropine, esmolol drawn up

vacuum insulated evaporator

Oxygen is a non-metallic element existing as a colourless odourless diatomic gas (O2) in the lower atmosphere and as a triatomic oxygen (O3) and monatomic oxygen (O) in the upper atmosphere.

Joseph Priestley is usually credited with the discovery of oxygen because he was the first to describe it in 1775 in his work entitled Experiments and Observations on Different Kinds of Air. However Scheele, a Swedish apothecary, first discovered oxygen in 1772.


Manufacture of oxygen

Oxygen is manufactured by the fractional distillation of air. Air is compressed to 5 atmospheres and cooled to -181oC using reverse heat exchangers. A two-stage distillation process yields 99.5% O2 (and 0.4% argon). It is stored at 137 bar in silver cylinders with green shoulders in the United States.

Storage of Oxygen: The VIE

Hospitals store large quantities of oxygen as a liquid in a vacuum insulated evaporator (VIE).



The inner shell of the VIE is made of stainless steel. It is separated from the outer carbon steel shell by an insulated gap with a vacuum of 0.16-0.3KPa. The contents are at 1000KPa and a temperature of -150oC (critical temp -119oC). A gauge indicates the pressure within and a differential pressure gauge (compares top to bottom) indicates the oxygen contents by weight.

Compensatory adjustments made by the VIE system

If there is a period of low oxygen use or hot weather this will result in the temperature of the liquid oxygen increasing.. This leads to increased pressure in the VIE and at 1500KPa the blowoff valve opens allowing vaporisation into the environment, (the latent heat of vaporisation cools the liquid oxygen).

If there is a period of high oxygen use by the hospital or very cold weather, there will be reflected by a decreased temperature of liquid oxygen and thus a decreased pressure in the VIE system. At 1000KPa the Pressure Raising Valve (PRV) opens, and allows liquid oxygen to shunt through a Pressure Raising Vapouriser (PRV). This allows environmental heat to enter the system. This mechanism ensures that the pressure and temperature of the VIE rises back to normal. All outgoing gases pass through a heat exchanger to warm them.


Tuesday, December 13, 2011

medical vivas

met roy after work (i was postcall)

STEMI
unilateral white out: differentials- previous pneumonectomy, hemothorax, collapse
bilateral pneumothorax
pleural effusion -transudative or exudative, light's criteria
Practice ACLS algorhythms

Time Is Of Essence.

'This CXR shows lung metastases as evidenced by bilateral cannonball lesions'

Wednesday, December 7, 2011

anaesthesia for renal transplant

Anaesthesia for renal transplant
1) comorbidities,
2) medications: immunosuppressants, anti-hypertensives
3) ESRF and underlying cause of it
-should have dialysis in 24 hours before op

Anaesthesia technique
GA: IPPV. (RA:caution in uraemic patients, residual heparin, concurrent liver disease)
CVP: for fluid monitoring. Aim 12-14. MAP: high normal
IA: not mandatory

TEE

Absolute contraindications:
Esophageal spasm.
Esophageal stricture.
Esophageal laceration.
Esophageal perforation.
Esophageal diverticula (e.g. Zenker's diverticulum).

Relative contraindications:
Large diaphragmatic hernia may significantly hinder TEE imaging because of lack of transducer mucosal approximation.
Atlantoaxial disease and severe generalized cervical arthritis: TEE should never be performed if there is any question about stability of cervical spine.
Patients who received extensive radiation to the mediastinum: this can cause significant difficulty in probe manipulation within the esophagus and is a relative contraindication if the anatomy of the esophagus is not known.
Upper gastrointestinal bleeding, significant dysphagia and odynophagia are also relative contraindications

Indication:
cardiac output
valve
congenital heart disease
evaluation of LA and LA appendage before cardioversion

Monday, December 5, 2011

Fat embolism

fat embolism-gurd criteria
major : (at least 1)
hypoxaemia
axillary or subconjunctival petechiae
CNS depression disproportionate to hypoxaemia
pulmonary edema

minor factors: (4 )
tachycardia >110
hyperthermia
sputum fat globules
retinal fat emboli
urinary fat
decreased platelets/haematocrit (unexplained)
increased ESR