Laparoscopic incisional hernia repair in a porcine model: what do transfixion sutures add?

BACKGROUND: The aim of this study was to evaluate the need for transfixion sutures during laparoscopic ventral hernia repair with mesh. METHODS: Incisional hernias were created in 14 Yucatan mini-pigs. Animals were randomized to undergo laparoscopic hernia repair either with spiral tacks alone (Tacks) or with tacks and 4 Prolene transfixion sutures (Sutured) using Composix E/X mesh (Davol Inc.). At 4 weeks, exploratory laparoscopy was performed to assess the repair and score adhesions. The abdominal wall was harvested for tensile strength analysis and histologic evaluation. Continuous variables were compared using a two-tailed nonpaired t-test. Results are presented as mean +/- standard deviation. RESULTS: The mean hernia size was 8.5 +/- 0.5 cm by 5.5 +/- 0.7 cm, with no difference between groups. The operative time was significantly longer ( p = 0.006) for the Sutured group (62.1 +/- 16.8 min) than for the Tacks group (32.3 +/- 7.0 min). The number of tacks per repair was equivalent between groups. At necropsy, the mesh in all cases was well incorporated, reperitonealized, and without evidence of migration. No hernias recurred. However, the Sutured group had a significantly ( p < or = 0.05) higher adhesion score (5.4 +/- 3.3) than the Tacks group (2.0 +/- 2.7). The tensile strength of the repair zone was no different between groups (Sutured 4.8 +/- 1.5 N/cm, Tacks 3.8 +/- 1.4 N/cm). On histologic examination, the ratio of inflammatory cells to fibroblasts was similar between groups (Sutured 0.2 +/- 0.6, Tacks 0.2 +/- 0.3). Only 82% of tacks in each group penetrated the fascia, and the depth of tack penetration was similar between groups (Sutured 3.7 +/- 0.3 mm, Tacks 3.9 +/- 0.4 mm). CONCLUSIONS: In a porcine model, the use of transfixion sutures was associated with longer operative times and more adhesions, without improvement in tensile strength or mesh incorporation. A human clinical trial is needed to determine the optimal method of securing abdominal wall mesh.

Production and systemic absorption of toxic byproducts of tissue combustion during laparoscopic cholecystectomy.

Among the potential hazards of laparoscopic surgery using electrocautery is the release of chemical by-products of incomplete tissue combustion into the pneumoperitoneum with subsequent transperitoneal absorption into the bloodstream and/or release into the operating room. The purpose of this study of patients undergoing laparoscopic cholecystectomy (LC) was twofold: (1) to assess the relationship between intraperitoneal concentration of carbon monoxide (CO) and blood levels of carboxyhemoglobin (COHb) and methemoglobin (MetHb), and (2) to assess the surgeon's inhalation of CO resulting from ambient smoke exposure. During LC with monopolar electrocautery, 21 patients were evaluated intraoperatively for intraperitoneal [CO] by sampling gas from a trocar, whereas arterial [COHb) and [MetHb] were determined perioperatively. The surgeon's venous blood was drawn pre- and postoperatively to assay [COHb] and [MetHb]. Patients completed visual analogue questionnaires 6 hours and 24 hours postoperatively to assess for adverse symptoms. Mean (+/- SEM) patient age and weight were 45 +/- 3 years and 84 +/- 4 kg, respectively. Mean duration of the operation was 69 +/- 5 minutes, and electrocautery was used for 3.0 +/- 0.3 minutes. Intraperitoneal [CO] rose to peak levels of 209 +/- 19 ppm at 50 minutes, whereas systemic [COHb] and [MetHb] were unchanged. The surgeon's systemic [COHb] and [MetHb] did not increase postoperatively. Nausea, abdominal pain, and fatigue scores decreased significantly between 6 and 24 hours postoperatively; however, there were no correlations between these symptoms and peak intraperitoneal [CO]. Although LC using electrocautery increases intraperitoneal [CO] to "hazardous" levels, systemic [COHb] and [MetHb] are not elevated by generation of intraperitoneal smoke. The surgeon's exposure to CO by the evacuation of smoke through laparoscopic ports is negligible. Production of smoke during LC using monopolar electrocautery, therefore, does not appear to pose a threat to either the patient or the surgeon.

Laparoscopic hepatic lobectomy in the porcine model.

BACKGROUND: To date, there have been only a few anecdotal reports of laparoscopic hepatectomy, most of which are limited to wedge resections. The aim of this study was to assess the feasibility of laparoscopic hepatic lobectomy in a porcine model. METHODS: Eight pigs were anesthetized before placement of an abdominal wall lift device and five laparoscopic ports. With the porta hepatis clamped, the left lateral hepatic lobe was divided with an ultrasonic dissector. Small vessels and ducts were clipped, larger vascular structures were transected with staplers, and surface hemorrhage was controlled with an argon beam coagulator. Serum liver enzymes (LFTs) and blood counts were drawn pre- and postoperatively. All animals were killed after 1 week. RESULTS: Mean +/- SEM operating and clamp times were 131 +/- 8 and 39 +/- 2 min, respectively. There were four intraoperative complications in three animals (three lacerations of the hepatic vein and one tear of the splenic capsule), all of which were controlled at surgery. Mean blood loss was 189 +/- 52 ml, and the mass of the resected specimen was 139 +/- 11 g. There were no postoperative complications or deaths. White blood cell count, hematocrit, and LFTs did not change postoperatively, except for aspartate aminotransferase (AST), which was elevated transiently. There were no bile leaks or intraabdominal abscesses. CONCLUSIONS: Laparoscopic left hepatic lobectomy was technically feasible in the porcine model using an abdominal wall lift device for exposure. Clinical trials are needed to assess its feasibility and limitations before laparoscopic hepatic lobectomy is deemed safe for human use.

Experimental development of an endoscopic approach to neck exploration and parathyroidectomy.

BACKGROUND: Recent advances in minimally invasive surgical technology have the potential to lead to new applications outside body cavities. The purpose of the present study was to develop techniques for obtaining endoscopic exposure and access to the pretracheal space in the neck with the goal of performing neck exploration and parathyroidectomy and to evaluate the safety and efficacy of such an approach experimentally. METHODS: The technique for endoscopic neck exploration was developed in eight adult mongrel dogs and was further evaluated in a survival dog model and in human cadavers. The pretracheal space was accessed by a 2.5 cm midline incision in the lower neck. This space was expanded with a balloon dissector, and exposure was maintained with an external lift device. A 5 or 10/12 mm midline port and two to four lateral 5 mm cervical ports were placed, and dissection was carried out with pediatric endoscopic instruments and an ultrasonic coagulator. Excised parathyroid tissue was verified histologically. RESULTS: Two-gland parathyroidectomy was successfully completed in five of six dogs; inadequate exposure led to a failed procedure in one animal. Mean operative time was 130 +/- 6 minutes, and there were no operative complications. Serum calcium levels did not change significantly after operation (p = not significant). At autopsy, approximately 20 ml of clear sterile fluid was present in the pretracheal space of every dog. In five human cadavers mean dissection time for attempted four-gland parathyroidectomy was 69 +/- 38 minutes (range, 45 to 135 minutes). Four of four parathyroids were identified and removed in two patients, three of three parathyroids in one patient, three of four parathyroids in one patient, and two of four parathyroids in one patient. CONCLUSIONS: Parathyroidectomy may be performed safely and reliably in an animal model with minimally invasive techniques that can be applied to parathyroid dissection in human cadavers. These results suggest that an endoscopic approach to neck exploration and parathyroidectomy is potentially feasible and may warrant further study in clinical trials.

Production and systemic absorption of toxic byproducts of tissue combustion during laparoscopic surgery.

BACKGROUND: Among the potential hazards of laparoscopic surgery using electrocautery is the intraperitoneal release and subsequent absorption of byproducts of tissue combustion. In a porcine model of laparoscopic surgery with smoke production, our aims were to assess (1) the relationship between levels of intraperitoneal carbon monoxide (CO) and systemic carboxyhemoglobin (COHb) and methemoglobin (MetHb), and (2) intraperitoneal concentrations of other noxious gases, including hydrogen cyanide (HCN), acrylonitrile (Acr), and benzene (Bzn). METHODS: Seven pigs underwent laparoscopic resection of three hepatic wedges using monopolar electrocautery in a CO2 pneumoperitoneum. Sequential arterial samples were drawn to measure [COHb] and [MetHb] perioperatively, while gaseous intraabdominal [CO], [HCN], [Acr], and [Bzn] were assayed intraoperatively. RESULTS: The mean +/- SEM duration of operation was 90 +/- 2 min, and electrocautery was used for 68 +/- 4 min. Intraabdominal [CO] rose from 0 to 814 +/- 200 ppm (p < 0.01) while [COHb] increased from 2.9 +/- 0.1% to 3.5 +/- 0.1% (p < 0.001). Systemic [MetHb] remained unchanged intra- and postoperatively, ranging from 0.3 to 0.7%. Intraperitoneal [HCN] rose from 0 to 5.7 +/- 0.7 ppm (p < 0.001). [Acr], however, did not change significantly from preoperative values, ranging from 0 to 1.6 +/- 1. 0 ppm, and [Bzn] was undetectable. CONCLUSIONS: Laparoscopic tissue combustion increases intraabdominal [CO] to "hazardous" levels leading to minimal, yet significant, elevations of [COHb]. Systemic [MetHb] and intraabdominal [HCN], [Acr], and [Bzn] are not elevated to toxic levels. Production of intraperitoneal smoke during laparoscopic electrosurgery therefore may not pose a significant threat to the patient.

Sutured or fibrin-glued laparoscopic choledochojejunostomy.

Minimally invasive techniques for choledochojejunostomy offer theoretical advantages for palliating unresectable periampullary neoplasms. Fibrin glue, a biologic adhesive containing concentrated fibrinogen, may obviate suturing and promote healing without stricture formation. We examined the technical ability to perform laparoscopic choledochojejunostomy (LCJ) and the applicability of thrombin-activated fibrin glue in an animal model of biliary obstruction. Domestic pigs underwent laparoscopic cholecystectomy and ligation of the distal bile duct. Three days later, a side-to-side LCJ was performed by intracorporeal sutured anastomosis (n = 7) or using four stay sutures and homologous fibrin glue (n = 7). Control animals underwent a similar bypass via open laparotomy (n = 7). The postoperative interval to ambulation and oral intake was recorded, and serial serum liver enzymes were measured. The animals were sacrificed at 6 weeks, and tensile strength of the anastomoses was assessed by tensometry. Liver function tests returned to normal values within 7 days following all methods of choledochojejunostomy. In the fibrin glue group, three anastomotic leaks (43%) occurred in the 1st postoperative week. At 6 weeks, all other anastomoses were intact and patent by cholangiogram, but there was moderate stenosis of two open and one fibrin-glue anastomosis. The sutured LCJ, while taking approximately 1 h longer to perform (P < 0.05), resulted in similar efficacy and more rapid recovery (P < 0.05) than open biliary-enteric bypass. Fibrin-glued LCJ was performed rapidly, but had less tensile strength (P < 0.05) and often leaked in the early post-operative interval. We conclude that while there may be a role for laser-activated solders for primary anastomosis, thrombin-activated fibrinogen cannot be advocated as the primary means of creating biliary anastomoses. Using intracorporeal suturing techniques, laparoscopic choledochojejunostomy may be performed safely.

Laparoscopic Billroth II gastrectomy in the canine model.

The feasibility and safety of laparoscopic Billroth II gastrectomy were evaluated in an animate model. After developing the technique in acute animal experiments, laparoscopic antrectomy and Billroth II anastomosis was performed in six mongrel dogs. Video laparoscopic access to the peritoneal cavity was accomplished with six ports (five, 10 mm; one, 12-18 mm). The operations were performed without complication in 150-200 min (mean +/- SEM, 171 +/- 10 min). The animals tolerated solid oral meals on the 2nd or 3rd postoperative day. One dog developed frequent diarrheal stools and lost 3.4 kg prior to sacrifice 18 days postoperatively when a gastroileostomy was discovered. The remaining five animals did well and were sacrificed at 49-77 days postoperatively. Adhesions were minimal and the gastrojejunostomy was widely patent in all animals without evidence of leakage or obstruction. Laparoscopic Billroth II gastrectomy in the canine model is thus feasible and safe. Using laparoscopic guidance, it may be more difficult to identify the ligament of Treitz, which must be assured at the time of operation.

Effect of ileal oleate on interdigestive intestinal motility of the dog.

To determine the effect of ileal oleate on fasting intestinal motility, pairs of duodenal and ileal catheters and bipolar duodenal and jejunal seromuscular electrodes were surgically implanted in six dogs. The ileum was perfused with either normal saline (154 mM NaCl) or oleic acid emulsion (152 mM), while intestinal myoelectric activity was continuously monitored. For transit studies, a bolus of [3H]PEG was injected into the duodenum, and jejunal and ileal alliquots were collected every 15 min for a 6-hr study period. Plasma samples were collected for radioimmunoassays of peptide YY and enteroglucagon. Ileal oleate infusion increased the MMC cycle length and decreased the number of MMCs (P < 0.001) and the myoelectric spike-burst frequency/10 min in the duodenum (P < 0.05). Both duodenal-jejunal (P < 0.05) and duodenal-ileal transit (P < 0.01) were delayed markedly by ileal perfusion with oleic acid emulsion as compared to control studies. Ileal oleate increased plasma levels of peptide YY (P < 0.01) and enteroglucagon (P < 0.01). Ileal perfusion with oleate therefore activated the so-called "ileal brake," diminishing duodenal myoelectric spike bursts and slowing intestinal transit while concurrently increasing plasma levels of peptide YY and enteroglucagon.

Laparoscopic distal pancreatectomy in the porcine model.

Our aim was to assess the feasibility and safety of laparoscopic distal pancreatectomy in an animate model. After developing the technique in acute animal experiments, laparoscopic distal pancreatectomy was performed in five young domestic pigs. Five trocars were used (2-10 mm, 2-12 mm, 1-11 mm) for video laparoscopic access to the peritoneal cavity. The operations were performed without complication in 62-95 min (mean +/- SEM, 77 +/- 7 min). Each animal tolerated oral feedings on the first postoperative day and subsequently gained 6-11 kg (10 +/- 2 kg) in the 4-7-week interval prior to sacrifice. Although there was a significant increase in serum amylase on the first postoperative day, this was associated with a comparable increase in hematocrit, possibly representing hemoconcentration. The weight of the laparoscopically resected pancreatic segment ranged from 16 to 36 g (19 +/- 2 g) while that of the pancreatic head at sacrifice was 13-29 g (21 +/- 3 g). At the time of sacrifice, there were few intraabdominal adhesions and no evidence of fluid collection or pancreatitis. The staple line across the body of the pancreas was grossly intact in all animals. We conclude that laparoscopic distal pancreatectomy in the porcine model is feasible and safe. It may therefore be possible to perform laparoscopic distal pancreatectomy in humans.

Inhibitory effect of ileal oleate on postprandial motility of the upper gut.

To determine the effect of ileal oleate on postprandial gastrointestinal motility, duodenal and paired perfusion-aspiration ileal catheters and bipolar duodenal and jejunal electrodes were surgically implanted in five dogs. The ileum was perfused with either saline or an isotonic oleic acid emulsion at 2 ml/min. A 205-kcal mixed meal containing 120 ml liquid nutrient labeled with 111In-diethylenetriamine pentaacetic acid (DTPA) and solid food labeled with 99mTc was then administered orally. Gastric emptying was assessed by a gamma camera, myoelectric activity was continuously monitored, and duodenal-ileal transit of phenol red was determined over the ensuing 240 min. Ileal oleate reduced duodenal spikeburst frequency by 50% (P less than 0.05) and delayed gastric emptying of liquids and solids. Four hours after ingesting the meal, 62% of solids and 34% of liquids were retained in the stomach during oleic acid perfusion compared with 25 and 4%, respectively, when saline was perfused (P less than 0.05). Duodenal-ileal transit was markedly slowed by ileal perfusion with the oleic acid emulsion (P less than 0.001). Ileal oleate therefore exerted a profound inhibitory effect on proximal gut motility in the early period after ingestion of a mixed-nutrient meal in dogs.

[Compression of the deep branch of the ulnar nerve as it exits the pisiform-unciform hiatus: report of an anomaly not yet described]. / Compression de la branche profonde du nerf ulnaire à la sortie du hiatus piso-unciformien. A propos d'une anomalie non encore décrite.

We observed a case of compression of the deep branch of the ulnar nerve distal to the piso-hamate hiatus due to an aberrant fibrous band arising from the hamulus ossi hamatum and ending in the flexor digiti minimi muscle. An anatomical study of eleven fresh cadaver hands revealed that between the piso-hamate hiatus and the palm, the nerve passes through an osteo-fibrous tunnel in which multiple anomalies can occur. The authors think that ulnar nerve neurolysis at the wrist must always extend up to the palm.

Crystallization of rat intestinal fatty acid binding protein. Preliminary X-ray data obtained from protein expressed in Escherichia coli.

Rat intestinal fatty acid binding protein has been expressed in Escherichia coli, purified with bound long chain fatty acids and crystals grown from solutions of polyethylene glycol 4000. The crystals are monoclinic, space group P2(1), a = 3638 A, b = 57.2 A, c = 31.9 A, and beta = 113.9 degrees. Each unit cell contains two monomers of this 132-residue, 15.1-kDa polypeptide. The crystals are remarkably resistant to x-ray damage. X-ray diffraction data have been observed to 2.0 A resolution. Platinum chloride was used to generate a potential isomorphous heavy atom derivative.

Purification, crystallization, and preliminary X-ray data for porcine fumarase.

Single crystals of fumarase purified from pig heart have been prepared from solutions containing polyethylene glycol. The crystals give diffraction data corresponding to Bragg spacings of 2.0 A and contain a single subunit of the enzyme in the asymmetric unit of the C222 unit cell. Therefore, the subunits of this tetrameric molecule are arranged with the point symmetry group 222. The present purification scheme and studies of the NH2-terminal amino acid sequences suggest that only a single form of the enzyme is present, and it is thought to be the mitochondrial enzyme.

Preparation of single crystals of a yolk lipoprotein.

Single crystals of a yolk lipoprotein from two species of lamprey oocytes have been prepared and shown to belong to the monoclinic space group C2. The unit cell dimensions combined with molecular weight determinations support the idea that the lipoprotein is a symmetrical dimer centered on a crystallographic 2-fold symmetry axis. The lipid content is estimated to be about 15% (w/w) and the crystals are suitable for structural studies by single crystal X-ray analysis. The X-ray results are correlated with those obtained by electron diffraction.

Follow-up of renin in essential hypertension.

In a prospective study of patients with essential hypertension, plasma renin levels showed a progressive increase with longer follow-up. This was associated with a parallel increase in renal vascular resistance. Arterial blood pressure and plasma volume did not change significantly during follow-up. In patients where the hypertension was complicated by myocardial infarction there was a comparatively greater increase in renin levels and renal vascular resistance which may be attributable to chronic reduction of cardiac output.