BT_PO 1.50 CVS and obesity

BT_PO 1.50   Describe the cardiovascular changes that occur with morbid
obesity

An increased extracellular volume may be a causative factor in hypertension in the obese  TRUE/FALSE

Blood volume per kg body weight is less in the obese than in the lean      TRUE/FALSE

Hyperinsulinaemia may be a causative factor in hypertension in the obese      TRUE/FALSE

A cuff that is too small will over-read the blood pressure in the obese      TRUE/FALSE

Fat blood flow is approximately 10 ml/min/100g      TRUE/FALSE

I have taken this from Hemmings and Hopkins Chapter 71 but the material is scattered throughout the recommended texts and can also be deduced if you have a good grasp of the topic

 

 

 

Ventilation and Perfusion

Since the pulmonary circulation operates at low pressure, the distribution of blood is similar to the distribution of ventilation. TRUE/FALSE

Alveoli with no ventilation will have PO2 and PCO2 values that are the same as mixed venous blood. TRUE/FALSE.

A pulmonary embolism is a shunt. TRUE/FALSE

Pulmonary capillary blood flow + Venous admixture = Cardiac Output. TRUE/FALSE

Venous admixture increases arterial blood carbon dioxide content above that of pulmonary end-capillary blood. TRUE/FALSE

Patient of the week – 2

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Another piece for the V&A, this made entirely from cutlery (I am drawing a long bow for today’s post)

Here is another case in this sporadic series

Some months ago I looked after a young patient who had been retrieved following a machete injury near the shoulder, resulting in almost total amputation of the arm. The injury had occurred some hours previously, with the patient left at the side of the road.

He had been intubated by the retrieval team at the scene.

On arrival to the Emergency Department his potassium level was 6.5 mmol/L

BT_GS 1.38

Normal serum potassium rise following an intubating dose of suxamethonium is 1.5mmol/L TRUE/FALSE

BT_PO 1.72

ECG changes associated with hyperkalaemia include tall peaked T waves and a shortened PR interval. TRUE/FALSE

He was taken to theatre to reattach the arm. He was hypovolaemic and anuric.

I set about trying to lower his serum potassium and restore his blood volume.

BT_PO 1.40

Salbutamol may be detected as halothane when nebulised within the circle circuit TRUE/FALSE

BT_PO 1.72

Calcium gluconate is used in the  management of hyperkalaemia as it lowers serum potassium TRUE/FALSE

BT_RT 1.9

Hyperkalaemia and hypercalcaemia are potential metabolic consequences of massive transfusion    TRUE/FALSE

To be honest, nothing I tired (and I tried a lot of everything I could think of, short of starting dialysis) lowered his potassium at all. But at least it didn’t increase any further. He survived the reimplantation  and was transferred to ICU for further management, including some much needed haemodialysis.

BT_RT 1.17 and 1.18 Adrenaline in shock and resuscitation

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Not sure that these fit the topic, but they were beautiful and I am a sucker for a rainbow (viewed at the V&A). I think these would give you a surge of dopamine rather that adrenaline, but we will save that for another day…

The current ARC guidelines (see 11.5) provide a very minimalist approach to drug therapy in cardiopulmonary resuscitation, emphasising the importance of high quality and minimally interrupted CPR. However of the couple of drugs left, adrenaline in front and centre.

BT_RT 1.17 With reference to the management of shock, describe the pharmacology of vasopressors and inotropes, including:

adrenaline,

and lots of other drugs (click on the link to view them)

BT_RT 1.18 With reference to cardiopulmonary resuscitation, describe the pharmacology of

adrenaline,

vasopressin,

amiodarone and

lignocaine

 

During cardiac arrest, adrenaline has a role in the treatment of both shockable and non shockable rhythms     TRUE/FALSE

Adrenaline has been shown to improve the chances of return of spontaneous circulation in arrest situations   TRUE/FALSE

Adrenaline is useful in the treatment of anaphylactic shock, in part, because it prevents further mast cell degranulation  via a beta mediated response TRUE/FALSE

Adrenaline may improve myocardial blood flow in low flow states as it causes aortic diastolic pressure to rise   TRUE/FALSE

If giving adrenaline via the endotracheal tube, the dose should be increased by 10 fold TRUE/FALSE

 

BT_RT 1.2 Integrate knowledge of factors determining cardiac output to classify causes of shock

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To fit with today’s theme is this photo of Tippoo’s Tiger, on display at the V&A Museum, London. This wind-up piece has an organ inside and when the handle was turned it supposedly “imitated the European victim’s dying wails of agony” – delightful! It was found in the music room of Tipu Sultan after his death in 1799

Let’s knock off another LO before we get started on the core business of today –

BT_RT 1.1  Define shock

Shock is defined as a state where tissue perfusion is inadequate to meet the metabolic requirements of that tissue     TRUE/FALSE

Ok, now for the main event. This topic is covered quite well in Oh’s Intensive Care Manual  and Guyton and Hall Textbook of Medical Physiology – details here. I suspect it is well covered in lots of places actually 😉

BT_RT 1.2 Integrate knowledge of factors determining cardiac output to classify causes of shock

All causes of shock are associated with an absolute reduction in cardiac output    TRUE/FALSE

Cardiogenic shock occurs when the heart is unable to pump blood sufficiently to maintain perfusion      TRUE/FALSE

Neurogenic shock and anaphylaxis are both examples of distributive shock  TRUE/FALSE

Anaesthesia may cause neurogenic shock     TRUE/FALSE

Hypovolaemic shock can be used to describe any form of shock where there is inadequate venous return   TRUE/FALSE

 

And finally one last photo of the tiger and its hapless victim…

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BT_SQ 1.13 Describe and classify breathing systems used in anaesthesia (episode 2).

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I photographed this little guy in Hong Kong – he’s (or perhaps she’s??) looking bit ragged. Following yesterday’s post I did a bit of research. It tuns out that sea jellies have no breathing system at all. They meet their oxygen requirements through diffusion across their bodies….

Today we will turn our focus to the circle system. This is something most of us use every day. I asked a viva on it in the last exam and was surprised by many of the answers I was given.

The circuit is circular with unidirectional valves – does that mean that gas flows in only one direction throughout the entire system?

BT_SQ 1.13  Describe and classify breathing systems used in anaesthesia. Evaluate their clinical utility and hazards associated with their use

The circle circuit, as commonly used in current anaesthetic practice, is a closed system  TRUE/FALSE

With the standard circle arrangement, fresh gas commonly flows through the CO2 absorber   TRUE/FALSE

Placing the APL valve before the CO2 absorber (on the expiratory limb) helps to conserve the CO2 absorbent  TRUE/FALSE

When running the circle as a closed circuit, minimal gas monitoring is required, as it is a stable system        TRUE/FALSE

A safe circle system requires the fresh gas flow to be placed between the patient and the expiratory valve  TRUE/FALSE

BT_SQ 1.13 Describe and classify breathing systems used in anaesthesia.

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What sort of  breathing system do those guys have? Certainly none of the ones we will be discussing today…

Today I will focus on the Mapleson classification of breathing systems. Here is an article written about them by Mapleson himself. He is still alive and in his 90s. You can read a little more about him here. Textbooks on the ANZCA primary exam reading list generally cover this topic adequately too.

BT_SQ 1.13 Describe and classify breathing systems used in anaesthesia. Evaluate their clinical utility and hazards associated with their use

The Mapleson A circuit is more efficient for a spontaneously ventilating patient compared with Mapleson D    TRUE/FALSE

A Mapleson E circuit is also referred to as classic T-piece     TRUE/FALSE

In the Mapleson D circuit the reservoir bag is located off the expiratory limb    TRUE/FALSE

The Mapleson D circuit is more efficient for controlled ventilation (CV) compared with spontaneous ventilation, due to the longer expiratory phase with CV    TRUE/FALSE

The Mapleson C circuit is the most efficient of these systems for spontaneous ventilation TRUE/FALSE

 

SS_OB 1.12 Labetolol

At least where I work we have to fill out the Special Access Scheme form to use IV labetolol, but worldwide it is a commonly drug for blood pressure control in pre-eclampsia, and it has many advantages over hydralazine.

SS_OB 1.12 Describe the pharmacology of agents used for the treatment of pre-eclampsia including magnesium, hydralazine and labetolol

 

T/F Labetolol is a non specific alpha antagonist

T/F Labetolol is a non specific beta antagonist

T/F A beta blocker with Intrinsic Sympathomimetic Activity is particularly useful for prevention of myocardial infarction

T/F Labetolol may cause profound foetal bradycardia

T/F Cardiac output rises after intravenous but not oral Labetolol

 

BT GS 1.12 Explain and describe the clinical application of concepts related to intravenous and infusion kinetics

Admittedly, this is a rather dry topic.  It is of unequivocal importance to anaesthetists however as our practice revolves around giving drugs that have potent pharmacodynamics effects with rapid onset and offset of action.

Regarding the time to peak effect (TTPE):

Is indicated on a plasma time curve for a bolus dose where the effect site curve crosses the plasma concentration curve TRUE/FALSE

Will be relatively short for any drug that rapidly redistributes TRUE/FALSE

Will be relatively short for drugs with a large keo TRUE/FALSE

Will always be longer than the t ½ keo TRUE/FALSE

Is considered to be a dose insensitive parameter TRUE/FALSE

BT PO 1.91 Outline the pharmacology of glucagon (& other things)

glucagon

Coming in an aesthetically pleasing little orange container, glucagon is a drug anaesthetists administer infrequently. Funnily enough the most common indication that we give glucagon for has nothing to do with hypoglycaemia. Rather it is given to treat suspected spasm of the sphincter of Oddi demonstrated on an intraoperative cholangiogram when performed during a lap chole. The second most common indication in our sphere of influence is probably the management of impacted food boluses. Both of these indications relate to the smooth muscle relaxant action of glucagon.

 

Glucagon is an anabolic hormone TRUE/FALSE

Glucagon is synthesized by the alpha cells of the islets of Langerhans TRUE/FALSE

Glucagon is effective in the management of beta blocker overdose because it  firmly binds to adrenoceptors TRUE/FALSE

Glucagon is an inotrope and chronotrope TRUE/FALSE

Glucagon binds to a G protein coupled receptor and inhibits adenylate cyclase activity and thus reduces cAMP TRUE/FALSE