How long is too long for robotic surgery?

A surgical chairman writes [some details were changed to obscure the surgeon’s identity]:

We currently have surgeons who are trying to establish themselves as experts in performing a certain robotic operation. As an open case, it rarely takes more than about 4-5 hours.

With the robot, it is generally taking around 6 hours as reported in the literature, and morbidity and mortality in expert hands appears to be pretty good.

What is happening in the real world is that surgeons are taking 12 or more hours to perform these operations robotically. I am aware of one death after a 14 hour procedure in another hospital. One case in my own institution took 16 hours, and luckily the patient did well. Of course this sort of data never gets reported publicly. 

Don't trust the abstract; read the whole paper

Above are the results and conclusion from an abstract of a paper called "Single-Incision Laparoscopic Cholecystectomy: Will It Succeed as the Future Leading Technique for Gallbladder Removal?" It appears online in the journal Surgical Laparoscopy, Endoscopy & Percutaneous Techniques.

It is another great example of why you need to read the entire paper and not just the abstract.

The methods section says that the study involved 875 patients with prospectively collected data. Don’t be fooled by prospectively collected data. This research is retrospective.

Here are some issues.

Can cholecystectomies safely be done at night?

A new study from surgeons at UCLA found that laparoscopic cholecystectomies done at night for acute cholecystitis have a significantly higher rate of conversion to open than those done during daylight hours.

Nighttime cholecystectomies were converted 11% of the time vs. only 6% for daytime operations, p = 0.008, but there was no difference in the rates of complications or hospital lengths of stay.

The study, published online in the American Journal of Surgery, was a retrospective review of 1140 acute cholecystitis patients, 223 of whom underwent surgery at night.

The authors advocate delaying surgery until it can be done in the daytime, but this conclusion needs to be examined.

Although the percentage of gangrenous gallbladders was similar in both groups, it wasn't clear from the data how many patients were semi-elective and how many were true emergencies.

Operative procedure durations were 110.5 minutes for nighttime and 92.4 minutes for daytime cases, and 1.5 and 2.0 days elapsed respectively before the patients were taken to the operating room, both p < 0.0001. The hospital lengths of stay were similar at 3.7 days for the night group and 3.8 days for the day patients. The causes for these lengthy operations, delays in operating, and long hospital stays were not explained in the manuscript.

Surgery in space: I foresee problems.

The astronauts are halfway to Mars when suddenly one of them develops abdominal pain and requires surgery. What will they do?

According to NASA, a miniature robot capable of assisting in surgery has been developed, tested in pigs, and is soon to be trialed in a weightless environment. The robot, which weighs less than 1 pound, can be inserted into the abdomen via the umbilicus and controlled remotely.

The press release from NASA said types of operations that the robot would be capable of performing were "emergency appendectomies, emergency cholecystectomies, emergency perforation of gastric ulcers [sic], and intra-abdominal bleeding due to trauma." NASA meant to say "repair of perforated gastric ulcers." Not surprisingly, many science reporters for media outlets, for example, SFGate and WiredUK, did not notice the error. New Scientist also missed it, but at least published a later correction.

However, even the famous da Vinci robot is incapable of performing surgery on its own.

The original idea was that a surgeon on the ground would direct the robot's movements, but that will not be possible for two reasons. In deep space, the time lag between the earthbound surgeon's actions and the robot's response would be too long, and a recent article about remote-controlled drone crashes highlighted the problems that can occur when links are lost or computers malfunction.

The plan is to train the astronauts to perform minimally invasive robotic surgery on each other. What could go wrong?

A lot.

Will automation affect surgeons' skills?

Although it has been known for over two years, news outlets are again reporting that automation is degrading pilots' skills. Links are here and here. I blogged about this back then as part of a comparison of pilots to surgeons. My point was that surgeons did not have autopilots to rely on in the operating room.

This new report has prompted some to wonder whether robotic surgery will lead to deterioration of surgeons' skills.

In my opinion, that is not likely at this time because the robot is not really doing the surgery by itself. It is simply a tool that helps the surgeon and is under the surgeon's complete control at all times (except when it runs amok).

However, ever since the advent of laparoscopic surgery over 20 years ago and its popularity for many of the common procedures surgeons do, there has been concern that surgeons may eventually lose proficiency for open procedures. And a number of other open operations have been done less frequently due to alternate ways of treating patients such as non-operative or interventional radiologic techniques.

Here are some examples from the ACGME resident log data for the academic years 1999-2000 and 2011-2012.



We are approaching the critical lower limit for open gallbladder surgery expertise especially when you consider that only the most difficult cholecystectomies will be done as open cases from now on.

What will happen in 20 years when few surgeons will have sufficient skill to do a very inflamed open gallbladder?

Does anyone really believe that a surgeon can confidently remove an enlarged spleen having done fewer than 2 such cases during training?

This is a bigger problem and far more pressing than the possibility that automation will render human surgeons obsolete.

There's another issue too, which is the predicted shortage of general surgeons in the near future. How are more surgeons going to be trained if there are not enough open cases to train the current number of graduating residents, of which there were 1092 in 2012?

Has anyone else thought about these questions?

Gallbladder surgery: Double jeopardy

Last month, I blogged about a paper from China that advocated removing just the gallstones and leaving the gallbladder in place. I wrote that such procedures had been tried in the early days of gallbladder surgery and failed because the stones recurred. You can read that post here.

It's not often that one gets to see almost immediate follow-up on a blog post like this, but I am happy to say that I can share a brief story with you.

A 44-year-old man (who consented to my blogging about him) underwent a cholecystectomy by a friend of mine a few weeks ago. The patient presented with right upper quadrant abdominal pain. He said that he had gallbladder surgery in a South American country in 2009 and had a large right subcostal incision to show for it.

In the emergency department of the hospital, a CT scan showed a large gallstone in what appeared to be a shrunken gallbladder. My friend obtained a copy of the operative report and a handwritten note from the original surgeon. See below.

The surgery that had been performed was a partial cholecystectomy and removal of a 6 cm gallstone.

My friend (and yes, he is still my friend) performed a robotic cholecystectomy. He said the surgery was difficult due to omental adhesions and the small size of the gallbladder. The specimen contained six 2 to 3 mm stones. The patient did well and was discharged.

OK, one case is an anecdote and doesn't prove anything, but its timely appearance doesn't hurt my position that just removing the stones won't cut it. (Pun intended.)

Gallbladder surgery goes back to the future in China

Chinese surgeons claim taking out just the gallstones without removing the gallbladder works well for most patients.

There were 65 patients with gallstones, 61 of whom underwent successful minimally invasive surgery for removal of just the stones leaving the gallbladder in place. The other four patients had laparoscopic cholecystectomies for various technical reasons. After an average follow-up of 26 months, the stone recurrence rate was 4.9% (3 cases).

Not mentioned in the abstract but noted in the methods section of the full article is that all patients were given a 3-month course of ursodiol postoperatively. The authors said it "adjusts the abnormal lipid metabolism in the gut-liver axis and prevents stone recurrence." This statement contains some truth up until the word "and." It's not clear how a short course of ursodiol would help.

Before the advent of laparoscopic cholecystectomy, doctors tried dissolution with ursodiol as a primary treatment. It worked 30-80% of the time for pure cholesterol stones, not those that were pigmented or calcified. About 50% of the time the gallstones recurred after the medication was stopped if the follow-up was long enough, that is, at least 7 years. [I had to go back to 1988 for this reference.]

Well over 100 years ago when open gallbladder surgery was first attempted, surgeons soon learned that removing the stones was inadequate treatment due to a high rate of recurrence.

Since the gallstone removal procedure involved general anesthesia and laparoscopy with two 10 mm and two 5 mm ports anyway, it makes absolutely no sense to just remove the stones. Most laparoscopic cholecystectomies are done with one 10 mm and three 5 mm ports so there is one less large incision which decreases the risk of postoperative hernias.

Here are some more issues.

Preoperatively, only 26 of the patients in the series had biliary colic. Gallstones with "atypical upper gastrointestinal symptoms" were present in 34, and 5 had no symptoms. Surgeons in the US generally would not have operated on patients in the latter two categories.

No mention was made of the duration of the operation, which involves laparoscopy with the 4 ports as noted above, insertion of a choledochoscope into the gallbladder, grasping the stones with a basket an unstated number of times, irrigation, and suture closure of the gallbladder wall.

The authors also that said except for the three recurrences of stones, gallbladder function was normal postoperatively. This was determined by ultrasonography after a fatty meal which took place every 6 months postop.

The three reoperations were done when stones were found by the ultrasound. Of those three, the authors said, "One patient remained asymptomatic, 1 patient experienced biliary colic, and the other patient had non-specific upper gastrointestinal symptoms (flatulence and dyspepsia)."

I don't see this procedure catching on here in the US. Do you?

UPDATE 3/25/14: See a follow-up post on this subject here.

Single-incision vs. standard 4-port laparoscopic cholecystectomy: Part 2

Here's another paper that shows why reading only an abstract can sometimes be misleading.

A prospective trial (abstract here) of 49 patients randomized to single-incision laparoscopic cholecystectomy (SILC) vs. 51 who had standard 4-port laparoscopic cholecystectomy (LC) found that average operative times were 63.5 ± 21.0 minutes for the SILC compared to 43.8 ± 24.2 minutes for those who had LC, and hospital charges were also more than $4000 higher for the SILC patients—both significant differences with p values < 0.0001.

Medical and surgical supplies were the major factors contributing to the increased charges for SILC.

Other than a significantly larger number of females in the SILC group, the patients were similar in baseline characteristics.

Other important considerations such as postoperative pain, hospital length of stay (an average of 24 hours or less for both operations), use of analgesics, cosmetic appearance of the wounds, rates of incisional hernia, and quality of life were similar. Average follow-up was 16 months in both groups. The authors concluded that there was no advantage to SILC.

Since this paper supports my bias against single-incision surgery, I was going to tout it as yet another negative paper like a recent meta-analysis (here) from a group in Croatia showing absolutely no advantage for SILC.

But this sentence from the "Methods" section of the paper foiled my plan. "Before partaking in the study, each surgeon developed his or her SILC technical skills in a laboratory setting and demonstrated proficiency during 5 SILCs under the supervision of a surgeon with experience on more than 50 SILC cases."

This was not mentioned in the abstract.

Are you surprised that a surgeon that might take longer to do SILC, an operation done only 5 times before, than LC, which each of the surgeons had probably done hundreds of times? Although the mean operative duration was longer for SILC, it is a "straw man" in statistical parlance. This may not detract from the rest of the results but certainly has to be considered.

As noted by the authors, the study was underpowered (that is, there weren't enough patients) to detect differences in some of the other outcomes due to difficulty recruiting subjects.

Of 946 patients offered enrollment in the study, only 103 consented. Patients declined to participate either because the surgeon explained that he had done more standard LC procedures, or the patients opted for the SILC because of its supposed cosmetic advantage.

The authors, based at Northwestern University Medical School in Chicago, should be commended for their honesty in explaining their inexperience with SILC to potential subjects of the trial and wonder if other surgeons who perform SILC do this.

This paper also highlights the problems associated with attempts to conduct randomized prospective studies involving new surgical procedures.

Bottom line: The extra costs associated with SILC are not worth it.

Part 1 of this 2-part series on SILC appeared on Tuesday, 2/18.

Single-incision vs. standard 4-port laparoscopic cholecystectomy: Part 1 of 2

The saying used to be, "You can get any paper published if you have enough stamps." Now with electronic submission, you don't even need the stamps.

A retrospective study comparing single-incision laparoscopic cholecystectomy (SILC) to standard 4-port laparoscopic cholecystectomy (LC) concluded that "SILC showed no disadvantage concerning risk profiles, operative times or hospital stay."

According to the abstract, 81.7% of the 115 SILC patients had elective surgery vs. 55.5% of the 344 in the LC group. The SILC cohort experienced significantly shorter operative times (70 ± 31 vs. LC: 80 ± 27 minutes) and hospital lengths of stay (3.02 ± 1.4 vs. LC: 4.6 ± 2.8 days), p < 0.001 for both. LC was converted to open surgery in 21 cases vs. none of the SILCs, p= 0.003. Rates of bile leak and incisional hernia did not differ.

Do you see any problems with this study? I do.

The groups were not really comparable because the LC group underwent more emergency operations. That difference is significant with a p value of 0.007—conveniently omitted from the abstract. The preponderance of elective cases likely accounts for the SILC group's shorter operative duration, lower rate of conversion to open, and shorter length of stay. The SILC patients were also a mean of 10 years younger.

The average operative time for the LC patients, 80 minutes, is much longer than the 40 to 45 minutes reported in most other recent series such as this one. In statistical circles, measuring one's pet theory against a false comparator is known as setting up a "straw man." I've written about this before.

This study was done in Germany, where the hospital lengths of stay for both types of surgery are far longer than those seen in the United States where about 90% of patients go home within 24 hours of laparoscopic cholecystectomy.

The authors concluded that "SILC can be regarded as a natural evolution in the era of minimally invasive surgery."

On the other hand "No disadvantage" is another way of saying, "No advantage."

This paper didn't convince me about the value of SILC. How about you?

Part 2 of this 2-part series on SILC appeared on Thursday, 2/20.

Sleep deprivation, surgeons, operations, and outcomes

A new paper found that surgeons who performed elective laparoscopic cholecystectomies after having operated the night before had outcomes similar to those when they were presumably well-rested.

The retrospective study involved 331 surgeons who did 2078 cholecystectomies after operating the night before and 8,312 when not operating the night before. Outcomes both were matched for each surgeon.

Comparing outcomes after operating the night before to not found rates of conversion to open - 2.2% vs. 1.9%, risk of iatrogenic injuries - 0.7% vs. 0.9%, and death - 0.2% vs. 0.1%, respectively. None of those differences were significant.

The abstract concluded, "These findings do not support safety concerns related to surgeons operating the night before performing elective surgery."

This paper is the latest of several that show similar results.

So case closed, right?

As much as I hate to say this, the paper does not prove that sleep deprived surgeons don't have more complications than when they are well rested. What it does prove is that conversion rates, not complication rates, are the same whether the surgeon got adequate sleep the night before or not.

In the paper, which was published in JAMA, the authors said, "Although not always considered a complication, conversion to open cholecystectomy may serve as an aggregate end point for many complications."

I disagree. I know of no previous study confirming that conversion of a laparoscopic cholecystectomy to an open procedure is a marker for complications. Instead, I believe it is a sign of good judgment. The sooner a surgeon recognizes that he can't safely do the procedure laparoscopically, the better off the patient is. A surgeon should never be discouraged from converting a case to open.

The study probably included enough patients to support its conclusion that there is no difference in conversion rates, but it is underpowered to detect a difference in iatrogenic injury rates or mortality because those events are so infrequent. To conclude that there is no difference in iatrogenic injury or mortality rates is what is known in statistical circles as a "Type II error" or failure to reject a false null hypothesis. The two null hypotheses in this situation were that there is no difference in 1) iatrogenic injury or 2) mortality rates when surgeons are rested or not.

In other words, the rates of iatrogenic injuries and deaths may not really be different, but the lack of a difference could simply be due to the fact that there were not enough subjects in the study. Iatrogenic injuries and deaths occur so infrequently with laparoscopic cholecystectomy that a study would need a lot more patients in each group to conclude that sleep is not a factor.

Most media coverage of the paper did not question its findings. Even Atul Gawande was hooked. Yesterday he tweeted "New @jama study of daytime surgery by surgeons who operated during night before: found NO increased complications."

Better studies on the effects of sleep deprivation on surgeon performance are needed before the issue is settled.

Is it really best to take out a gallbladder in the daytime?

Under the headline "Best to take out gallbladder in daytime," MedPage Today reports on a study that says people who have laparoscopic cholecystectomies at night have more complications.

The work was presented at Digestive Disease Week in Orlando.

Ordinarily, I would not critique a paper that I had not read completely but I have to make an exception in this case.

There are some serious issues with both the research and the reporting. If the MedPage article is not read carefully, patients may receive inappropriate or delayed care.

According to the article, the paper comprised 549 patients who were mostly female (84%) with 65% having surgery in the daytime (defined as 7 a.m. to 7 p.m.), and 62% had surgery that was not elective—that is, urgent or emergent.

Those operated on at night had a longer median hospital length of stay, 3 days vs. 1 day and were more likely to have had non-elective surgery, p < 0.001 for both.

The article also says the nighttime patients "were more likely to have a discharge diagnosis." I'm only guessing, but I think they may have meant to say "a discharge diagnosis of acute cholecystitis."

"Bile leaks, bile duct injuries, retained stones, pneumonia, and readmission occurred at rates that did not differ significantly," says the report. The only complication that differed significantly was that of superficial wound infection, which occurred in 5% of the night and 2% of the day patients, p = 0.04.

Multivariate analysis showed that nighttime surgery increased the odds of complications by just over 3 times but with a wide confidence interval of 1.01-10.7 and a barely significant p value of 0.05.

So, what's the problem?

At the very end of the nearly 500-word article, we find that elective patients were excluded from the multivariate analysis with no explanation why. It could be that when the elective patients were included, there was no difference in outcomes.

The first part of the last sentence is even more revealing: "The authors also did not have data on postoperative length of stay and severity of gallbladder disease."

Perhaps some of the length of stay of 3 days for the nighttime patients was due to waiting for an available operating room, workup for possible common duct stones or stabilization of lab values.

But in my opinion, the factor that makes the entire study invalid is not knowing the severity of the gallbladder disease. A patient with a more severely inflamed gallbladder is obviously more likely to have a complication.

There is also no mention of co-morbidities like diabetes or heart disease which may have been more prevalent in the nighttime group.

I don't understand how this study ever saw the light of day, why it was selected as a featured paper by MedPage or why the misleading headline was used.

If you are a patient with a sick gallbladder, many recent studies have shown that you should have it removed as soon as possible—less time in the hospital, less cost better outcomes.

If your surgeon can do it at 8 p.m., please go ahead with the surgery. Don't wait until the next day.