Most recent update: Tuesday, February 18, 2020 - 09:47

Bariatric News - Cookies & privacy policy

You are here

Ashish Sinha

The anaesthesiologist in bariatric surgery

Bariatric News speaks to Dr Ashish Sinha, an anaesthesiologist specialising in extremely obese patients at Hahnemann University Hospital, Philadelphia, about the challenges he faces when treating bariatric patients.

Dr Ashish Sinha at the recent Alpine Experts Obesity Meeting in Saalfelden, Austria.

What is your background, and how did you become involved in bariatric anaesthesiology?

I started with a year of general surgery. I liked the operating room, and I thought if I just stayed in the operating room, I would have to be an anaesthesiologist. And that was fine; anaesthesiology has been very good to me.

Once I finished my training – I trained at the Baylor College of Medicine in Houston – I worked for a while at MD Anderson, and then I did a seven-year stint at the University of Pennsylvania. There, I picked obesity as my specialty.

Very quickly – some self-taught, some learnt – I got to the point where I became relatively proficient. I started enjoying it, and my surgical colleagues appreciated what I did. I began speaking not only to anaesthesiologists, but also to surgeons. Hopefully I’m disseminating information, but also collecting information. My talk only gets better if my audience gives me tips about the things they do which adds to that.

"Obesity is a growing problem. No pun intended. Obese patients are showing up in every operating room, from obstetrics, to paediatrics, to trauma." Dr Ashish Sinha

Why obesity?

One – it’s a growing problem. No pun intended. Obese patients are showing up in every operating room, from obstetrics, to paediatrics, to trauma.

So whatever operating room or subspecialty of anaesthesia you look at, there’s a problem. The problem is size. Now, this is a problem all across the world. At this point there are more people globally who are malnourished from obesity than from true weight loss, from being too small.

I decided, okay, this is a developing field; there aren’t that many experts in it. Maybe I could make a contribution on the front end, where the specialty is developing. At the University of Pennsylvania, where there’s about 70+ anaesthesiologists, there’s a core group of five people. For seven years, I was a member of this core group and we did all the morbidly obese and ultra-obese patients; mostly for weight loss, but for other things as well.

Once a patient came in over 200 kilos, the tendency was to ask the people who are very comfortable with patients in that weight range to do the case, whether it be trauma, a liver case, or whatever, because of comfort, familiarity, and because of the challenges.

What are the common problems you see when anaesthetising the obese patient?

From an anaesthesiologist’s point of view, it starts with starting the IV. If your hand was swollen to three times its size, your veins are going to hide; they’re going to disappear. Right now I can see them, but if I can’t see them, and they’re so deep that I can’t feel them, that’s challenge number one.

I choose the inside of the wrist. I find that’s a good spot; other people don’t look at it. Sometimes I use the anterior chest wall. I have used an IV anywhere I can get it.

We can always do an external jugular by putting the patient head-down. In most instances, it’s very easy, but when a patient weighs 200 kilos, they don’t tolerate a head-down position. They can’t breathe. In that patient it’s not an obvious solution. You can always use ultrasound-guided internal jugular vein access, but the easier solutions start going away. The challenges multiply.

Intubation can be a challenge. Obese patients have very low reserve, and a very high metabolic demand, so they’re losing on both ends – they don’t have an oxygen bank, and they’re consuming it much faster. As soon as you flatten them, their ratios change, and now their lung is not expanding as well. The exchange of oxygen is decreasing, so you have to protect them by forcing the lung to expand.

There are other things we do like recruitment manoeuvres, forcing the lung to expand by squeezing a bag which is connected to the lung. Once it can expand, it can exchange oxygen. If it collapses, it cannot exchange oxygen.

Even once you’ve secured the airway, then the problem is at the end of the case, how do you extubate the patient? If they’re uncomfortable, in pain, then the problem is that they’re going to breathe shallow and rapidly – they’re going to tire out and need to be reintubated.

If you give them too much narcotic, they don’t want to breathe. You take away their desire. You have to balance it nicely – good pain control, but not so much that they don’t want to breathe.

Post-operatively, that’s one of our biggest challenges. Intraoperatively, the antibiotics has to be right; the deep-vein thrombolytics have to be right. When you do a safety check, you make sure that the antibiotic has been administered. The normal one gram of the cephalosporin may be increased to two grams. An infection in this patient population is much worse in terms of outcome.

Do you start to see new problems, novel things that you haven’t seen before, as people get larger and larger?

The original operating room tables were designed for patients up to 150 kilos. What happens when the patient is more than that? The table will tilt and fall over. The centre of gravity is too high; the base is not heavy enough. If the surgeon asks you to tilt the patient to the right or the left, the whole table tumbles.

Or the patient is so large, they can’t fit on one table – they’ll hang off on both sides. Sometimes we put sleds on the side, or small extenders around the elbow, so the patient’s arm can rest. But this can make it very inconvenient for the surgeon, because they’re over-reaching. They’re ergonomically disadvantaged.

The peak pressure of the lungs require different mechanics of the ventilators. The modern ventilators do very well, but some of the older ventilators don’t have those ventilatory options. Then we have a challenge. These mechanical problems are solvable, but they require resources.

"The surgeon comes into the room, the patient needs to be ready for them to start operating. But what goes on before then is a whole series of small challenges." Dr Ashish Sinha

Do you think that surgeons understand the difficulties that you face, or do they tell you, just knock him out and get him ready for me?

In some ways, you’re right. The surgeon comes into the room, the patient needs to be ready for them to start operating. But what goes on in between the time when the patient rolls into the operating room until the point where the surgeon can put his knife on the patient is a whole series of small challenges.

That is why, more and more, it’s becoming a subspecialty. I’d put that in quotation marks, because it’s not a true subspecialty, but once you do this all the time, you pick up little tricks – where you’re going to place your IV, how you’re going to position the patient’s head, what tricks you’re going to use in intubation, what kind of drugs are you going to use. Those things are specific challenges that the surgeon doesn’t really 

It’s not really their problem! I’m not going to help the surgeon do their surgery; to some extent, the surgeon can’t help me do the anaesthesia. But one without the other doesn’t work. Both of us have developed our specialties as the challenges have increased.

How often do you see patients who you think are too heavy to be put under?

I don’t see that – my personal heaviest are very heavy, in the 800-pound range, with a 110 BMI. But for other people, a patient who’s 250 kilos is so far out of their comfort zone that they say, I can’t do this safely. Which is absolutely fine – you don’t want to find that you can’t do it in the middle of a case.

It’s okay to say, let’s do this as a local anaesthetic, or let’s do this another day with somebody else helping me, or at another centre where they have the equipment, the skill, the expertise to do patients this large.

What are your own contributions to bariatric anaesthesia?

I don’t think I’ve actually invented anything, as much as modified things, to the point where people would tongue-in-cheek refer to it as my technique.

I modified something we were doing using the aintree – a hollow tube that can be put in the airway to act as a guide for the endotracheal tube. The way it is placed in the airway is over a fibre-optic scope. In a patient where there is a challenging anatomy, you can do this without an intermediate step, but we adapted an intermediate step from an LMA – a laryngeal mask airway – so that we could continue to ventilate these patients through the intubation.

In other words, this patient is not apnoeic and very quickly desaturating. So we can continue to oxygenate and anaethetise through the laryngeal mask airway. We’re connected to the circuit, putting oxygen into the patient’s lungs, we’re putting in anaesthetic gas, while we are creating a more permanent access to the airway.

I cannot do this with an LMA alone, because of the nature of the surgery – it’s a laparoscopic surgery. Belly pressures are going to go up; it’s a large patient, you’re going to have problems with reflux – those are contraindications for LMA. But I can use the LMA on the front end enough to get the endotracheal tube in there.

So the LMA goes in, then the aintree-loaded fibre optic goes in through the LMA via an adaptor that fits at the end of the LMA through which a surgeon can do bronchoscopy, meaning we can go in through the LMA. We take out the fibre optic, leaving just the LMA and the aintree in the airway. Very carefully we remove the LMA, without displacing the aintree. All we have in the airway at this point is an aintree catheter.

On top of the aintree catheter we put an endotracheal tube, remove the aintree catheter and secure the airway. You can always verify the position of the endotracheal tube using a fibre-optic scope. Now we can put the patient flat, if we have to; we can put the patient head-down, head-up, whatever the surgeon requires. We don’t worry about it.

"Make sure you have a plan to reverse back out of the situation. You need a way to walk back along the plank, instead of jumping off into the shark-infested water." Dr Ashish Sinha

Do you think that the way forward for anaesthesiology is more people like you who are specialised in bariatrics, or more for general anaesthesiologists to learn more about the kind of things you’re doing?

There are a few societies that are devoted anaesthesiologists who are interested in increasing their expertise about this. One is the International Society for the Perioperative Care of the Obese Patient; people can become members and get information. We’re trying to create an active forum. If you have a question about a patient coming into your OR that you’re not familiar with, reach out to us.

We’re always available – even if you’re in eastern Europe and you’ve got a question you think we’d be able to help you with, shoot us off a question. I’d be happy for somebody to call me in the middle of the night and say, look, I have a problem, do you have a solution?

Email me and figure out a way to contact me, and I’ll say, this is what I’d do. Or this is what I wouldn’t do. That should work, but if that doesn’t work, make sure you’ve got a plan B and a plan C, and a plan to reverse back out of that situation. Wake the patient up.

Any damage you do at intubation is iatrogenic – caused by the physician. And you don’t want to be responsible for that. You need a way to walk back along the plank onto the ship, instead of jumping off into the shark-infested water.