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.