Why surgeons need to know about anaesthesia
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During laparoscopic surgery, it is important to secure adequate surgical workspace. This can be obtained by improved neuromuscular blockade during the procedure. However, there are a lack of knowledge about neuromuscular blockade in anaesthesia in general among surgeons and a lack of knowledge about surgical technical issues among anaesthesiologists.
The issues are discussed based on the available literature.
Knowledge between the two specialities is highly relevant and is typically lacking. There are data to support the fact that the abdomen may be tense although there are clear signs of neuromuscular blockade on the TOF-watch. This situation can be easily explained by the pharmacodynamics of the neuromuscular blocking agents, and it means that the anaesthesiologist is overestimating the level of blockade.
There are potential problems during laparoscopic surgery where a better communication and collaboration between surgeon and anaesthesiologist may be beneficial for patient outcome.
KeywordsLaparoscopy Surgery Neuromuscular blockade Anaesthesia Learning
Although the surgeons and anesthesiologists have the same goal, that is, to get the patient through the procedure with safety and solving the surgical indication for the operation, there may still be a split focus in the operating room based on traditions and lack of collaboration as well as communication between the two specialties. A typical situation could be when the surgeon is not satisfied with the level of muscular blockade during the operation. The scenario could be that the surgeon asks for more blockade, but the anaesthesiologist will say that blockade is deep enough. So who is right and who is wrong? The anaesthesiologist will often hesitate to use deeper levels of relaxation, especially towards the end of the procedure, and most surgeons have never experienced a deep block sustained throughout the surgical procedure. In daily clinical practice, all surgeons have asked for additional relaxation because of contractions in the abdominal wall or even patient movements. The anaesthesiologist may not regard this as a serious problem, but from the surgical point of view it may be a factor that will make the surgical procedure more difficult or even dangerous. Anaesthesia is a key factor to get better surgical conditions during the procedure, but the anaesthesiologist may not always know exactly what the problem is for the surgeon. Therefore, a qualified dialogue between the two specialties with better communication and even collaboration is very important to ensure best possible patient outcome. The present paper will try to highlight the issues of interest in order for the surgeon to be able to ask for anaesthetic alterations on an informed basis.
Optimized surgical exposure
Surgical exposure can be optimized by pneumoperitoneum for laparoscopic procedures, by positioning of the patient (Trendelenburg or anti-Trendelenburg positions or rotating to the side), and finally by the use of muscle relaxation. In a previous study in patients undergoing laparoscopic cholecystectomy, the procedure could be completed with intraabdominal pressure at only 8 mmHg in 60 % of patients receiving deep neuromuscular blockade compared with 35 % of patients having a moderate neuromuscular blockade . Optimal surgical conditions during the entire procedure were present in 28 % in the deep neuromuscular blockade group compared with 4 % in the moderate neuromuscular blockade group . The European Association for Endoscopic Surgery has recommended using the lowest intraperitoneal pressure allowing adequate exposure of the operative field rather than using a routine pressure . A way to lower intraabdominal pressure during laparoscopic procedures is to employ a deeper level of neuromuscular blockade. Because surgical complications due to inadequate exposure are a rare event, the typical way to study this issue is to focus on a surrogate endpoint such as surgeon’s satisfaction . Another outcome parameter is the occurrence of sudden contractions in the diaphragm or the lateral abdominal muscles during the procedure, which may be an important safety outcome parameter . A randomized trial in laparoscopic cholecystectomy with no versus deep neuromuscular blockade showed fewer sudden contractions and inadequate visibility with deep versus no neuromuscular blockade during the operation . In a study in patients undergoing laparoscopic hysterectomy where they were randomized to moderate versus deep neuromuscular blockade, the overall findings were the same that the occurrence of sudden contractions in the diaphragm or lateral abdominal muscles, the occurrence of insufflator alarms, and increased abdominal wall tension were significantly more frequent in patients undergoing moderate versus deep neuromuscular blockade during surgery . Thus, a deep neuromuscular blockade during laparoscopic procedures will impair muscle contractions and give a better workspace for the surgeon.
So, what is a deep level of neuromuscular blockade?
The level of blockade is typically measured by the use of the TOF-watch that will give an electrical stimulus to the ulnar nerve and measure the contraction in the adductor pollicis muscle. A moderate level of blockade is typically defined as a TOF level of 1–2. In order to measure a so-called deep level of neuromuscular blockade, another measurement has to be done, that is, the post-tetanic count (PTC), where more stimulations are given to the nerves, and the number of contractions are then measured. A PTC level of 1–2 is usually considered to be a deep level of neuromuscular blockade. However, this reflects the level of paralysis at the adductor pollicis muscle, and thus a surrogate endpoint as the diaphragm and the lateral abdominal muscles is relevant for the surgical conditions. Of interest in this context is that the diaphragm is significantly more resistant to the neuromuscular blocking effects of nondepolarizing myorelaxants. Thus, there may be contractions in both the diaphragm [7, 8] and the lateral abdominal muscles  even with no contractions detected by the TOF-watch at the adductor pollicis muscle. This can be seen when the blockade is wearing off so the clinical scenario where the surgeon experiences abdominal muscle contractions and the anaesthesiologist cannot measure anything at the adductor pollicis is a fully explainable situation based on the pharmacodynamics of the neuromuscular blocking agent. In this particular situation, the anaesthesiologist is overestimating the degree of neuromuscular blockade.
How can we get a relaxed abdomen at the end of operation for closure?
For surgical technical reasons, it may be advantageous to have neuromuscular blockade to the end of the operation. However, neither the surgeon nor the anaesthesiologist would like to have prolonged anaesthesia or even residual blockade after the procedure. It is therefore impractical to employ neuromuscular blockade towards the end of the procedure without an effective reversal agent, and this problem is present during both laparoscopy and laparotomy. The traditional reversal agent has been neostigmine for decades . However, the time for reversal of neuromuscular blockade with neostigmine is unpredictable because of great inter-individual variation . Nevertheless, there is a newer drug on the market, sugammadex, which will fully reverse even a deep neuromuscular blockade within few minutes in all patients . Thus, there is a solution to the problem of the tense abdomen towards the end of the procedure, and that would be to use neuromuscular blockade until the very end of the operation and then reverse with sugammadex.
In daily clinical practice, if the surgeon asks for relaxation or “a deeper level of anaesthesia” towards the end of the procedure, then many anaesthesiologists or nurse anaesthetists will increase the dose of either propofol (i.e. the hypnotic component of general anaesthesia) or remifentanil (the analgesic component of general anaesthesia) for a short period of time in order to avoid a reinjection of a neuromuscular blocking agent, thus anticipating problems related to residual neuromuscular blockade after surgery. Most of these measures will normally not improve the surgical conditions, and sometimes they may even worsen them. Moreover, in critically ill patients these measures may destroy hemodynamic stability.
Turnover time is an important issue because economic constraints are pushing production. It is therefore important to have a short turnover time between cases and indeed not to cancel cases at the end of the day. There are various factors involved in reducing turnover time, but also here, anaesthesiological issues may be of importance. The general anaesthesia should end as close to the end of surgery as possible and of course still be safe. For sedation and analgesia, this is nowadays typically done by using short-acting compounds such as propofol and remifentanil. The timing of these drugs can be “refined” so that the patient will wake up soon after end of surgery. If, however, a neuromuscular blocking agent has been administered towards the end of the procedure, then it may take longer for the patient to wake up, and in this situation, use of neostigmine is not the solution because of its unpredictable action and prolonged time to effect . However, sugammadex allows now for the first time a tailor-made approach to neuromuscular block management as it may reverse rapidly and predictably even a deep level of neuromuscular blockade. Use of sugammadex, which will be effective within a few minutes in all patients, can therefore help to get the patient awake immediately after end of surgery and still give an effective neuromuscular blockade towards the very end of the procedure. There is in this way a management issue in the use of an effective reversal agent for neuromuscular blockade, and the expense of the drug may therefore be counteracted in some institutions by the possibility of doing an extra case during a working day, by not having to cancel the last case on the list, or by avoiding to pay for overtime to nurses and doctors.
In order to improve outcome and give a smoother patient journey in the perioperative setting, it seems vital to teach surgeons about anaesthesia as well as teach the anaesthesiologists about surgery. Interaction between the two specialties has to be intensified not only with communication but with true collaboration in order to improve outcome and give increased hospital efficiency at the same time. A good example of this is the enhanced recovery programs where a multidisciplinary approach is enforced on all parts of the patient’s journey with improved outcome and shorter hospital stay as obvious results . An easy start in gaining better understanding between the specialties could be the development of web-based learning programs or even organization of joint meetings on perioperative care issues with attendance of both surgeons and anaesthesiologists. This could be satellite symposia at surgical or anaesthesiological congresses or even stand-alone symposia focusing on collaboration.
Compliance with ethical standards
Dr. Rosenberg reports grants from Johnson & Johnson, grants and personal fees from Bard, and personal fees from Merck, outside the submitted work; Dr. Fuchs-Buder reports personal fees from MSD, outside the submitted work.
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