IT_GS 1.8 Physiological changes associated with pneumoperitoneum and their implications for anaesthesia

Another practical LO for today. Miller’s Anaesthesia used to have a chapter devoted to this topic, but unfortunately it has vanished from the current edition. There is however a quite nice little section at the end of Chapter 21

Here is another brief overview of anaesthesia for laparoscopy. In the middle there is a section on the physiological changes. It is worth remembering that a number of the effects are worsened as the intra-abdominal pressure generated increases (one of the reasons for the alarm on the gas insufflation machine).

This chap (a male frigate bird) doesn’t have a pneumoperitoneum, but rather an inflated gular pouch – apparently irresistible if you are a female frigate bird. They can fly with that pouch inflated (I’ll show you a photo of that tomorrow)

IT_1.8  Outline the physiological changes that occur with and the implications for anaesthetic management of pneumoperitoneum
Harking back to yesterday’s post what do you think the effect of pneumoperitoneum is likely to be on renal function?

A pneumoperitoneum causes activation of the sympathetic nervous system TRUE/FALSE

Release of a pneumoperitoneum may be associated the ischaemia-reperfusion injury TRUE/FALSE

Pneumoperitoneum may be associated with abdominal compartment syndrome TRUE/FALSE

Trendelenberg positioning can reverse some of the haemodynamic effects of pneumoperitoneum  TRUE/FALSE (what effect will it have on the respiratory consequences?)

Pnemoperitoneum reduces respiratory system compliance TRUE/FALSE 

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

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

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.

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

Answers available to another structure quiz

Here are the answers to Another structure quiz published last week.

How did you go?

And here, just because it is beautiful (and as mentioned previously, I am somewhat fascinated by them), another sea jelly. This one residing at the Monterey Bay Aquarium.

AR_ME 3.2 Discuss everything which could be construed as being related to anaesthesia

AR_ME 3.2 Demonstrate knowledge and understanding of the procedure including indications, contraindications, anatomy, technique side-effects and complications

This follows on from AR_ME 3.1 which is not examinable in the primary:

Demonstrate proficiency with:
 Vascular access
 Airway management
 Central Neuraxial block
 Other regional procedures
 Invasive monitoring procedures

T/F The Primary examiners have developed a sudden passion for anatomy.

T/F You are now required to know all about regional blockade when you sit for the Primary

Whilst this is only my humble opinion rather than an official ANZCA publication:

Asking regional blocks would be a major change in the scope of the primary. A change of this magnitude would not be slipped into the exam without a clear announcement from the College. So I will go out on a limb, and say: You will not be asked about subjects which are not in the non AR_ME LOs.

The examiners do not write the LOs, but I believe that the two AR_ME LOs which relate to the primary have been inserted to make it clear that when you study for the primary you should consider clinical applications, and when you are practising anaesthesia you should understand its grounding in science. I think you would be quite safe to ignore AR_ME 3.2 & AR_ME 1.3 (Apply knowledge of the clinical and biomedical sciences relevant to anaesthesia), as long as you realise that you will be asked about the clinical implications of the subjects you have studied.

As I am accustomed to say, if you don’t know the dose of propofol in an anaesthetic pharmacology exam you are in the wrong specialty 😉

 

 

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.

 

2.

3.

 

4.

5.

6.

7.

8.

9.

10.

 

 

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.

 

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 😊

 

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…..