BT_PO 1.71 Explain the effects on anaesthesia on renal function

I didn’t realise that this LO existed – found it when I was looking for a renal topic to post on, as there seem to be a dearth of renal posts on this site.

This is actually an important topic as relatively minor reductions in renal function are associated with worse peri-operative outcome.

I don’t have any kidney photos. Below is the best I could do for the genitourinary system. There are a whole series of these (some much more X rated) on view at MONA

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BT_PO 1.71  Explain the effects on anaesthesia on renal function

Any anaesthetic agent which results in a reduction of blood pressure is likely to reduce GFR   TRUE/FALSE

Attenuation of the stress response to surgery is renal protective   TRUE/FALSE

Volatile anaesthetic agents may provide protection against ischaemia- reperfusion injury of the kidney TRUE/FALSE

IPPV improves renal blood flow TRUE/FALSE

Metabolic acidosis increases the kidneys’ vulnerability to nephrotoxins TRUE/FALSE

BT_PO 1.54 Pharmacology of beta receptor blocking agents

jan 2006 156

I asked about these drugs in the recent in exams and was fascinated (read horrified and astounded) that only one person had a plausible explanation as to how these little chaps cause hypotension…..

These drugs are actually mentioned in 5 LOs BT_PO 1.54 and BT_PO 1.57-1.60

We see a lot of patients on these drugs, partly because they have been shown to confer a survival advantage in people with heart failure, so it is probably a good idea to know a bit about them…

BT_PO 1.54 Describe the pharmacology of commonly used alpha and beta receptor blocking agents, their clinical use, adverse effects and use in the perioperative period

 

Metoprolol is metabolised by the CPY2D6, and hence prone to large inter individual variation in response   TRUE/FALSE

Beta1 selective blockers produce a significant reduction in blood pressure when given to normotensive individuals     TRUE/FALSE

Hypotension with beta blockers is mediated by the dilation of vessels in skeletal smooth muscle   TRUE/FALSE

Beta blockers cause a reduction in the release of renin TRUE/FALSE

Some beta blockers have an alpha agonist effect TRUE/FALSE

BT_PO 1.125 Pharmacology of cancer chemotherapeutic agents, especially problems that such agents may cause during the perioperative period

I was asked about this in my Primary Exam! I have to admit that I had elected not to study the chemotherapeutics, (not a strategy that I would recommend 😉) but fortunately I was able to drag something from the back of my brain….

There is one chemotherapeutic drug in particular which has very significant anaesthetic implications ( I was unaware of this 20 yrs ago!) and you should have some knowledge of it.

Several others can have effects on organ systems which may be of consequence once anaesthesia is administered.

There is an  overview of the topic, with an anaesthetic bent, here, but all the standard texts will have chapter on chemotherapeutic agents.

rosy-periwinkle-400x266

Several chemotherapeutic drugs, including vincristine, are derived from the above plant, the Madagascar Periwinkle…..

BT_PO 1.125 Outline the pharmacology of cancer chemotherapeutic agents with particular reference to problems that such agents may cause during the perioperative period

The risk of oxygen induced pulmonary toxicity, following bleomycin treatment, persists for life  TRUE/FALSE

Anthracyclines, such as doxurubicin and daunorubicin, may cause an acute myocarditis TRUE/FALSE

Anthracyclines may cause a chronic dilated cardiomyopathy, which is dose dependent in nature TRUE/FALSE

Vincristine can cause both a peripheral and autonomic neuropathy TRUE/FASLE

The bone marrow suppression associated with chemotherapy usually preserves platelets TRUE/FALSE

Another structure quiz

This seemed to be popular last time.

As with the structures shown previously, you are unlikely to have to draw these in the exam. Some of them, you wouldn’t be expected recognise. If you don’t recognise the molecule, have a look at its structure and see what clues that gives you to its function. Several of the molecules are related to each other. All of these molecules are, or have been, used in anaesthetic practice.

I have included a couple of historic interest

1.

Chloroform

 

2.

iso-structure

3.

medchem1ic_Enflurane_full_498_229__0_native

 

4.

1200px-Codein_-_Codeine.svg

5.

1200px-Morphin_-_Morphine.svg

6.

150px-(1S,2S)-Tramadol_gespiegelt.svg

7.

naloxone.jpg.pagespeed.ce.Q70R1-33LY-2

8.

Tubocurarine.svg

9.

g-386

10.

g-590

 

 

BT_GS 1.16 Describe alterations to drug response due to obesity

Ok, I’ve paraphrased that LO a bit, so that we can stay with the topic for one more day.

We give drugs to people with a high BMI on a daily basis (at least at the institution I work in..), so it is important that we know what the implications of a larger lipid load are and how to adjust our dosing…

For today’s picture I have chosen another one of Andy Paiko’s amazing glass works.

andy-paiko-glass-syringe

 

BT_PO 1.16  Describe alterations to drug response due to physiological change with particular reference to the elderly

This is a complicated issue [I’m giving you a free true statement]

It is appropriate to dose muscle relaxants, such as vecuronium and rocuronium, based on ideal body weight (IBW)    TRUE/FALSE

When using propofol for maintenance of anaesthesia, calculate the infusion rate based on total body weight (TBW)    TRUE/FALSE

The increased cardiac output seen in morbid obesity, will hasten recovery from volatile anaesthesia TRUE/FALSE

Plasma levels of pseudocholinesterase are increased with morbid obesity TRUE/FALSE

Suxamethonium doses should be based on TBW  TRUE/FALSE

BT_PO 1.37 Describe the effect of morbid obesity on ventilation

Sticking with the topic of obesity.. The reference sources from  yesterday  will be valuable…

Look at that dessert (and the look of glee on my daughter’s face!). I can’t remember what it was called – obscene? -but just looking at it makes me put on weight 😊

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BT_PO 1.37 Discuss the effect of the following on ventilation:

  • Changes in posture
  • Exercise
  • Altitude
  • Anaesthesia
  • Ageing
  • Morbid obesity

Morbid obesity is associated with decreased compliance of the respiratory system    TRUE/FALSE

FRC is 25% lower in a person with a BMI of 30kg/m2 compared with a person with a BMI of 20kg/m2    TRUE/FALSE

Resting  respiratory rate is increased by morbid obesity      TRUE/FALSE

The alveolar to arterial gradient (A-a gradient) of oxygen is increased with morbid obesity      TRUE/FASLE

The effects of obesity on the respiratory system are improved by lying down TRUE/FALSE

Are your patients talking about this…..

Two posts in one day!! Thought I might as well post about this whilst it was back in my brain.

On June 7 Richard Fidler conducted an interview on ABC local radio, on the topic of consciousness and anaesthesia.

Two patients asked me about it within 24 hrs of it airing……

One, who had listened to it on the day of his procedure, was mildly terrified by the interview ( I hadn’t heard it at that stage, but did my best to reassure him).

I listened to the interview on my walk in to work the following morning.

The first patient of the day mentioned the interview to me. She was fascinated! She had me repeat a random word to her throughout the case to see if she could recall it after the event – she couldn’t! [although I didn’t hypnotise her]

It came to mind today as I was listening to one of my favourite podcasts, Chat10Looks3 , where the interview is discussed again.

It is worth listening to. Make up your own minds about it. It is always good to be cognisant of the information out patients are receiving about our specialty – the information doesn’t always come from us…..

BT_PO 1.50 Describe the cardiovascular changes that occur with morbid obesity

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I know those guys guys above are highly trained athletes, but…..

BT_PO 1.50  Describe the cardiovascular changes that occur with morbid obesity

This topic is not well covered in the standard primary exam texts. A textbook previously on the primary examination reading list, Foundations of Anaesthesia , had a whole chapter (Ch 71) devoted to the topic. Unfortunately, the new iteration of the book, Pharmacology and Physiology for Anaesthesia by Hemmings and Egan (a great book to look at), has dispensed with the subject – drats!!

The ANZCA library has three ebooks devoted to the peri-operative management of the morbidly obese. Each of these books has sections detailing the basic alterations of physiology associated with obesity. The most comprehensive of these is Morbid obesity: perioperative management 2e edited by Alvarez et al.

For those of you without access to the ANZCA library, here is a overview of some of the issues, from the little CME journal produced by the same group as the BJA.

Cardiac output increases linearly in proportion to free fat mass          TRUE/FALSE

Blood volume on a mL/kg bases is increased in the morbidly obese    TRUE/FASLE

Left ventricular hypertrophy (LVH) is common in morbid obesity, even in the absence of hypertension      TRUE/FALSE

Standard ECG criteria for diagnosing LVH are valid in morbid obesity   TRUE/FALSE

Angiotensinogen is produced by visceral adipocytes resulting in excessive angiotensin II TRUE/FALSE

Queen’s Birthday Special

It seems serendipitous that last week’s posts were obstetric related and today is the Queen’s Birthday holiday…

Queen Victoria was a relatively early adopter of anaesthesia and received chloroform anaesthesia for the birth of her 8th and 9th children, Leopold in 1853 and Beatrice in 1857. The chloroform was administered via an open drop technique, during the second stage of labour, with the aim of achieving semi-consciousness. The Queen is quoted as saying the chloroform was “soothing, quieting and delightful beyond measure”

 


It was James Simpson who, in 1847, first suggested the use of anaesthesia for labour. Initially obstetricians were almost universally opposed to the use of anaesthesia for labour, citing it as unnecessary for a natural process and concerned for the safety aspects.

John Snow, who anaesthetised Queen Victoria on both occasions, was a physician with a career spanning interest in anaesthesia. He experimented widely, on animals, using different inhaled substances in an attempt to find superior anaesthetic agents. He realised that the volatility of an agent declined as it was vaporised , due to the drop in temperature. Consequently he developed and early vaporiser, with a brass chamber which was immersed in water, to minimise temperature fluctuations. He appears to have been a man of great scientific rigour, which likely inspired confidence amongst the Queen’s physicians and eased the path for her to receive anaesthesia, when she and Prince Albert requested it. He was also a strong proponent of a doctor separate to the surgeon administering the anaesthetic. One of his major works On Chloroform and Other Anaesthetics and their Administration was published following his death is 1858. If you click on the title it will take you to a copy of the book, with William Morton’s name handwritten across the top!

John Snow made another great contribution to medicine as an epidemiologist. He was a believer that cholera was transmitted by contaminated water, contrary to popular belief at the time. Following an outbreak in London in 1854, he conducted an extensive epidemiological investigation tracking the details of victims and non victims to identify where they sourced their water. He identified the likely source as a pump on Broad Street, Armed with his research, he went to town officials and convinced them to remove the pump handle, making it impossible to draw water from the pump. The outbreak stopped almost instantly! It wasn’t until 1883 that Vibrio cholerae was isolated by Robert Koch and the means of transmission confirmed.

John Snow died age 45. Just imagine what he might have contributed to our speciality ( and others) if he had lived a long life……

John_Snow