Remote ischemic preconditioning improves tissue oxygenation in a porcine model of controlled hemorrhage without fluid resuscitation.

Remote ischemic preconditioning (RIPC) involves deliberate, brief interruptions of blood flow to increase the tolerance of distant critical organs to ischemia. This study tests the effects of limb RIPC in a porcine model of controlled hemorrhage without replacement therapy simulating an extreme field situation of delayed evacuation to definitive care. Twenty-eight pigs (47 ± 6 kg) were assigned to: (1) control, no procedure (n = 7); (2) HS = hemorrhagic shock (n = 13); and (3) RIPC + HS = remote ischemic preconditioning followed by hemorrhage (n = 8). The animals were observed for 7 h after bleeding without fluid replacement. Survival rate between animals of the RIPC + HS group and those of the HS group were similar (HS, 6 of 13[46%]-vs-RIPC + HS, 4 of 8[50%], p = 0.86 by Chi-square). Animals of the RIPC + HS group had faster recovery of mean arterial pressure and developed higher heart rates without complications. They also had less decrease in pH and bicarbonate, and the increase in lactate began later. Global oxygen delivery was higher, and tissue oxygen extraction ratio lower, in RIPC + HS animals. These improvements after RIPC in hemodynamic and metabolic status provide essential substrates for improved cellular response after hemorrhage and reduction of the likelihood of potentially catastrophic consequences of the accompanying ischemia.

Novel self-fixation chest drain device tested in a swine model of pneumo-hemothorax.

INTRODUCTION: Thoracic injuries account for 20-25% of trauma-related deaths. In cases of pneumothorax the insertion of a chest tube is mandatory but associated with high complication rates particularly when inserted under difficult conditions. The C-Lant is a novel chest-tube insertion device that provides integrated double fixation capabilities and can be used by responders with minimal experience. The aim of the study was to test the device in a large animal model. MATERIAL AND METHODS: Pneumothorax, tension pneumothorax, and hemothorax were induced in four white domestic female pigs. The C-Lant device (Vigor Medical Technologies, Haifa, Israel) was inserted as any chest-drain to decompress the thorax. Pull test was applied to test the strength of device fixation. RESULTS: The insertion of the device was simple and effective without detectable negative physiological effects. Reliable fixation was achieved without difficulty. Air and liquid were promptly drained from the chest cavity. Minimal tissue laceration occurred when applying the device in a scenario of erroneous pneumothorax diagnosis with fully expanded lungs. Interconnection with other surgical accessories was smooth. CONCLUSION: The C-Lant is a novel device that facilitates easy insertion and fixation of chest-tubes by minimally experienced medical providers and reduces the likelihood of unwanted expulsion. Clinical studies are planned.

The approximated cardiovascular reserve index complies with haemorrhage related hemodynamic deterioration pattern: A swine exsanguination model.

BACKGROUND: To estimate the cardiovascular reserve we formulated the Cardiovascular Reserve Index (CVRI) based on physiological measurements. The aim of this study was to evaluate the pattern of CVRI in haemorrhage-related haemodynamic deterioration in an animal model simulating combat injury. METHODS: Data were collected retrospectively from a research database of swine exsanguination model in which serial physiological measurements were made under anesthesia in 12 swine of haemorrhagic injury and 5 controls. We calculated the approximated CVRI (CVRIA). The course of haemodynamic deterioration was defined according to the cumulative blood loss until shock. The ability of heart rate (HR), mean arterial blood pressure (MABP), stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) and the CVRIA to predict haemodynamic deterioration was evaluated according to three criteria: strength of association with the course of haemodynamic deterioration (r2 > 0.5); threshold for haemodynamic deterioration detection; and range at which the parameter remained consistently monotonous course of deterioration. RESULTS: Three parameters met the first criterion for prediction of haemodynamic deterioration: HR (r2 = 0.59), SV (r2 = 0.57) and CVRIA (r2 = 0.66). Results were negative for MABP (r2 = 0.27), CO (r2 = 0.33) and SVR (r2 = 0.02). The detection threshold of the CVRIA was 200-300 ml blood loss whereas HR, SV and CO showed a delay in detection, MABP and CVRI exhibited a wide indicative range toward shock. CONCLUSIONS: The CVRIA met preset criteria of a potential predictor of haemorrhage-related haemodynamic deterioration. Prospective studies are required to evaluate use of the CVRI in combat medicine. LEVEL OF EVIDENCE: Level III.

Transesophageal endoscopic myotomy for achalasia: recognizing potential pitfalls before clinical application.

BACKGROUND: Laparoscopic Heller esophagomyotomy is the standard of care for achalasia treatment. This procedure, although effective, must be performed with the patient under general anesthesia and is associated with several serious potential complications. The authors aimed to develop a method of performing transesophageal endoscopic esophagomyotomy (TEEM) that would obviate the need for both general anesthesia and external incisions while offering lower intra- and postoperative complications. METHODS: The TEEM procedure was performed on eight pigs. For six of the pigs, the procedure aimed at survival. A mid-esophageal mucosal incision was performed using an endoscope, and a submucosal plane was developed. The lower esophageal sphincter (LES) muscle fibers were clearly visualized and divided. The mucosal incision was closed using fibrin sealant. After 2 weeks of survival, a gastrografin swallow study and necropsy were performed. RESULTS: The TEEM procedure was performed successfully in all eight porcine models. The myotomy included the LES fibers and extended 4 to 6 cm proximally to the esophagus. The proximal gastric muscle was divided up to 1 to 2 cm. No injuries to the abdominal or mediastinal structures occurred. One pig died on postoperative day 1 due to an unrecognized pneumothorax. Two pigs had ischemic ulcers at the myotomy site. The last three pigs had an uneventful recovery. The mucosal incision site healed completely in all the survived pigs, and except for the pig with mediastinal sepsis, all ate heartily and gained weight as expected. CONCLUSION: The TEEM procedure is technically feasible. Due to the morbidity encountered in the first three pigs, the reported technique was modified to include a slimmer endoscope, a shorter tunnel, and a partial-thickness myotomy. These changes together with an understanding of the pitfalls involved in this procedure led to successful results for the next three pigs. Nevertheless, the authors believe that TEEM is not yet ready for prime time. Perfection of the technique and development of dedicated instruments are mandatory before safe translation of this method to human patients.

Laparoscopic infrared imaging--the future vascular map.

OBJECTIVE: One of the most significant limitations of laparoscopic surgery is the inability to achieve tactile assessment of structures during surgical dissection. Because blood vessels are naturally warmer than their surroundings, infrared (IR) detection can be highly effective in identifying and mapping out their course. In recent years, IR detection has been used successfully for this purpose in open surgery. Nevertheless, this technology has to be yet employed in laparoscopic surgery, where its contribution would be greatest. METHODS: We performed a feasibility study using this technology on live porcine models. After insertion of IR detectors into the insufflated abdomen, we performed a series of laparoscopic procedures. During these operations we evaluated the ability of the IR detector to identify blood vessels as well as the effects of local and systemic changes in temperature. RESULTS: The IR detector successfully identified concealed blood vessels as well as acute bleeding. Cool lavage and insufflation with room-temperature CO(2) accentuated IR detection of blood vessels, whereas warm CO(2) and systemic temperature changes did not affect detection. Additionally, localized heating of tissue on the operative field using electrocautery did not interfere with IR sensitivity. CONCLUSION: Laparoscopic IR imaging is a feasible method of blood vessel detection in laparoscopic procedures. Use of IR blood vessel detection in laparoscopy has a potential to enable safer surgery and reduce operative time. Fusion of IR imaging with the standard laparoscopic view is currently being developed to allow real-time vessel mapping during laparoscopic procedures.