D. W. Meijer

Sensitivity of laparoscopic dissectors. What can you feel

AbstractBackground: Sensory feedback is reduced considerably in minimally invasive procedures by the interposition of instruments, causing loss of direct manual contact with the tissue. The purpose of this study was to evaluate the feedback quality of commercially available reusable and disposable laparoscopic dissectors.n Methods: A total of 31 participants were asked to feel a simulated arterial pulse with their bare fingers and through laparoscopic dissectors, tweezers, an orthopedic forceps, and a laparoscopic low-friction prototype. The absolute sensory threshold was determined by the psychophysical method of limits.n Results: The sensory feedback quality was significantly better for the reusable dissectors tested than for the disposable dissector (p < 0.001). Nevertheless, the reusable dissectors were at least eight times less sensitive than bare fingers. Furthermore, sensitivity qualities were highly variable, depending on the dissector tested.n Conclusions: This study showed that the overall sensitivity loss through instruments could be accurately assessed, proving that the sensory feedback for commercially available instruments was low compared to bare fingers. The good sensory feedback results of the prototype indicated that careful design could decrease the overall sensitivity loss.

Hand-assisted laparoscopic surgery : An overview

BackgroundAdvanced laparoscopic surgery is complex and time-consuming. Achieving consistent efficacy and safety throughout the entire procedure is always a problem. For this reason, hand-assisted laparoscopic surgery (HALS) was developed.MethodsDevices were designed to allow manual access to the abdomen through the utility laparotomy. By using one hand in the abdomen during laparoscopy, the surgeon regains direct tactile sensation and acquires improved handeye coordination. The safety of the individual devices has been tested in RCT for the registration of the individual devices. An index known as Surgical Action Efficiency was calculated for in six patients undergoing laparoscopic colon resection and six patients with hand-assisted colon resections.ResultsAll of the registered devices are safe. Surgical Action Efficiency for the laparoscopy group was 55±14%; for the HALS group, it was 71±4%. his result is statistically significant (p<0.05).ConclusionHALS is a safe and efficient method by which it is possible to combine the established convenience and safety of open surgery with the advantages of minimally invasive surgery.

Improved usability of a new handle design for laparoscopic dissection forceps

Background: Recent studies have shown that the shape of most instrument handles causes user discomfort and that none of the handles currently available on the market satisfies all ergonomic criteria. Therefore, we designed a handle with improved usability; i.e., it is easier to manipulate and its use entails less risk of injury for the operator. The aim of this study was to demonstrate that the intended improvements of the new design were successful. Methods: Six handles representative of the types that are currently available were compared with the new version. Eight surgeons used the seven handles during a precision task and a rough task in a pelvi-trainer. A questionnaire and video analyses were used to assess the usability of the handles. Results: Based on the responses to the questionnaire, we determined that there were significant differences between the new handle and the Aesculap handle (means of rotation and angle between handle and shaft). No significant differences were found between the new handle and the five other handles. The video analyses (documenting extreme vs neutral wrist excursions) showed significant differences between the new handle and the six other handles. Conclusion: Compared to the six existing handles, the new handle has significantly improved usability; in particular, its hinged design obviates the need to make extreme wrist excursions.

Hemodynamics during laparoscopic extra- and intraperitoneal insufflation An experimental study

AbstractBackground: Total extraperitoneal laparoscopic surgery is an alternative to the laparoscopic transperitoneal route; however, its effects on hemodynamics have not been adequately studied. This experimental study compared the effects of intraperitoneal insufflation and extraperitoneal insufflation on hemodynamics and oxygen transport.nn Methods: Sixteen pigs were randomly assigned for intraperitoneal insufflation or extraperitoneal insufflation with 15 mmHg carbon dioxide. Hemodynamic and oxygen transport parameters were taken during an hour of insufflation and analyzed for statistical differences.nn Results: During extraperitoneal CO2 pneumoperitoneum central venous filling pressures (central venous pressure, pulmonary capillary wedge pressure and mean pulmonary arterial pressure) and end-tidal CO2 increased slower but to a similar magnitude in comparison to intraperitoneal insufflation. Cardiac output and indices of oxygen consumption and oxygen delivery were equally affected by both types of insufflation. Arterial CO2 pressure increased significantly more during intraperitoneal insufflation.nn Conclusion: The data from this study suggest that extraperitoneal insufflation might result in less cardiovascular impairment than intraperitoneal insufflation.n

Laparoscopic cholecystectomy using abdominal wall retraction: hemodynamics and gas exchange, a comparison with conventional pneumoperitoneum

AbstractBackground: Disadvantages related to CO2 pneumoperitoneum have led to development of the abdominal wall retractor (AWR), a device designed to facilitate laparoscopic surgery without conventional pneumoperitoneum (15 mmHg CO2). We investigated the effects of the AWR on hemodynamics and gas exchange in humans. We also investigated whether the use of an AWR imposed extra technical difficulties for the surgeon. A pilot study revealed that cholecystectomy without low-pressure pneumoperitoneum was technically impossible.n Methods: A prospective randomized controlled trial: Twenty patients undergoing laparoscopic cholecystectomy were randomly allocated into group 1: AWR with low-pressure pneumoperitoneum (5 mmHg), or group 2: conventional pneumoperitoneum (15 mmHg).n Results: Surgery using the AWR lasted longer, 72 ± 16 min (mean ± SD) vs 50 ± 18 min compared with standard laparoscopic cholecystectomy. There were no differences between the groups with respect to hemodynamic parameters, although a small reduction of the cardiac output was observed using conventional pneumoperitoneum (from 3.9 ± 0.7 to 3.2 ± 1.1 l/min) and an increase during AWR (from 4.2 ± 0.9 to 5.2 ± 1.5 l/min). Peak inspiratory pressures were significantly higher during conventional pneumoperitoneum compared to AWR. A slight decrease in pH accompanied by an increase in CO2 developed during pneumoperitoneum and during the use of the AWR. In both groups arterial PO2 decreased.n Conclusions: The results indicate that the view was impaired during use of the AWR and therefore its use was difficult and time-consuming. Possible advantages of this devices effects on hemodynamics and ventilatory parameters could not be confirmed in this study.

Hemodynamics during laparoscopy in the supine or prone position

During laparoscopy elevations in arterial pressure and a decrease in cardiac output have been reported. Laparoscopic surgery performed in the prone position may be advantageous for some surgical procedures, but the hemodynamic effects of pneumoperitoneum in this position have not been studied. We studied the effects of different levels of increased intraabdominal pressure on hemodynamics and oxygen transport in eight pigs in the prone and the supine position. Increases in intraabdominal pressure did not result in decreased cardiac output or in a reduction of oxygen transport and consumption in either position. These results suggest that laparoscopy in the prone position does not result in more severe hemodynamic depression than laparoscopy in the supine position.

The prone position: using gravity for a clear view

Obtaining a clear view during laparoscopic surgery in the posterior abdominal cavity, on the abdominal backwall, or during colon surgery is time consuming and therefore one of the major objections to these procedures. In an experimental setting we positioned the animals in the prone position using the abdominal flanks to introduce the trocars. Our experience with this position is that a clear and unobstructed view of the abdominal back wall and the large intestines is obtained, facilitating laparoscopic procedures in these areas.

Experimental videothoracoscopic cannulation of the left atrial appendix

SummaryRapid implementation of left ventricular assistance without thoracotomy for temporary support of patients with severe, life-threatening, acute cardiac power failure potentially expands applications of such support devices. A thoracoscopic technique for direct cannulation of the left atrium is described. In healthy closed-chest pigs, it proved a feasible method for effective volume unloading of the left ventricle.