Optimizing Surgical Conditions During Laparoscopic Herniotomy With Deep Neuromuscular Blockade

Umbilical herniotomy is a frequent surgical procedure worldwide, and the larger hernia defects are preferably operated by laparoscopic technique. The advantages of the laparoscopic approach are shorter convalescence with earlier mobilization, and less wound complications [1]. A preferred approach is currently to close the defect by laparoscopic suturing in order to reduce the formation of seroma in the hernia sac [2] , and then apply a mesh by intraperitoneal onlay technique (IPOM technique). However, it may be difficult to suture the defect if there is tension in the abdominal wall muscles together with the applied pneumoperitoneum.

There is evidence that muscle relaxation improves conditions for endotracheal intubation[3] and reduces laryngeal morbidity but only a few studies investigate the necessity of relaxation during laparoscopic surgery [4].

During laparoscopic surgery muscle relaxation is used with great variability. Sometimes the procedure is performed without muscle relaxation and sometimes with a so-called surgical neuromuscular blockade, which with objective neuromuscular monitoring means that train-of-four (TOF) is kept at 3-4 responses to nerve stimulation of the ulnar nerve. In this way there is a great variability in the neuromuscular blockade and rarely the patients are receiving deep neuromuscular blockade.

Traditionally, neuromuscular monitoring is done by measuring the muscle strength of the adductor pollicis muscle on the thumb. The response to TOF nerve stimulation may be zero, while muscle relaxation of more resistant muscles such as the abdominal muscles and the diaphragm [5;6] are not complete which means that the patients may cough and their abdominal wall may feel "tight" during surgery, even though no response at the thumb is recorded. It is possible to quantify a deep neuromuscular block by the use of post-tetanic-count (PTC). With establishment of deep, continuous neuromuscular blockade with PTC value 0-1 all muscles including abdominal muscles and diaphragm are paralyzed [7]. It is therefore possible, that a deep neuromuscular blockade (NMB) where the diaphragm and the abdominal wall muscles are more paralyzed will optimize the surgical work space, ease the surgical procedure, reduce operative time for the suturing part of the procedure as well as the total procedure time, and reduce the number of recurrences by long term follow-up.

The purpose of this study is to investigate surgical work space and surgical conditions in patients scheduled for laparoscopic umbilical, -linea alba and incisional herniotomy. The patients will act as their own control with evaluation of surgical work space and surgical conditions during both deep NMB and no NMB.

Hypothesis:

Deep NMB defined as TOF=0 and post-tetanic count PTC ≥1, will give better surgical workspace, better surgical conditions, as well as shorter duration of surgery and reduced number of recurrences of hernias compared with no NMB.