Experimental carbon dioxide pulmonary embolization after vena cava laceration under pneumoperitoneum

Novel Epicardial Access Technique Facilitated by Carbon Dioxide Insufflation of the Pericardium for Ablation of Ventricular Arrhythmias: Lessons From the Early Experience From a Single Centre in Australia

INTRODUCTION

Epicardial access for mapping and ablation of the epicardial substrate may be required in catheter ablation of ventricular tachycardias (VT). However, high complication rates are associated with the standard epicardial access approach. Recently, a novel method of intentional coronary vein (CV) exit with pericardial CO₂ insufflation to facilitate epicardial access has been described. This study describes our initial experience with this technique.

METHODS

Patients undergoing epicardial VT ablation between 1 February 2021 to 31 May 2022 at the Royal Prince Alfred Hospital, Sydney, NSW, were included in this study. Via femoral venous access, a branch of the coronary sinus was sub-selected and intentional CV exit was performed with a high tip load coronary angioplasty wire. A microcatheter was then advanced over the wire into the pericardial space, followed by pericardial CO₂ insufflation, facilitating subxiphoid pericardial puncture.

RESULTS

Five (5) patients underwent epicardial access for VT mapping and ablation. All patients had successful intentional CV exit and CO₂ facilitated epicardial access. The mean time to successful epicardial access was 37.2±17.5 minutes. With increasing operator experience, there was improvement in epicardial access times, with the fifth case requiring only 13 minutes. There was one case of inadvertent right ventricular puncture (without haemodynamic or ventilatory compromise) due to inappropriate CO₂ insufflation into the right ventricle. Epicardial access was successful on the second attempt.

CONCLUSION

This is the first case series of epicardial access facilitated by CO₂ insufflation in Australia. This technique enabled successful epicardial access in all patients in our early experience, with no adverse outcomes from epicardial access. With increasing operator experience, this technique may allow for more widespread adoption of up-front epicardial access for the treatment of VT.

Positive Intrapleural Pressure with Carbon Dioxide May Limit Intraoperative Pulmonary Arterial Bleeding: Verification by Animal Model

PURPOSE

Intraoperative complications, especially unexpected bleeding, are of great concern in the safety of thoracoscopic surgery. We investigated the hemostatic efficacy and safety of positive intrapleural pressure (PIP) with carbon dioxide insufflation by assessing the amount of blood loss in a pulmonary arterial hemorrhage model.

METHODS

An ex vivo experimental model of saline flow into a swine vessel was created in a container simulating a chest cavity. From the results, in vivo experiments (swine model) were conducted to compare the pulmonary arterial bleeding volume while applying PIP.

RESULTS

In the ex vivo experiment, regardless of the incision type, the outflow volumes did not significantly differ at flow pressures of 20, 30, and 40 mmHg. At each flow pressure, the outflow volumes at 10, 15, and 20 mmHg of positive pressure in the container were significantly smaller than those of the control (p = 0.027, p = 0.002, and p = 0.005, respectively). Similarly, the in vivo experiments showed that bleeding decreased as intrapleural pressure increased (slope = -0.22, F = 55.13, p <0.0001).

CONCLUSION

It may be possible to temporarily suppress pulmonary arterial bleeding by increasing the intrapleural pressure to 10 to 20 mmHg using carbon dioxide insufflation. This method may be an adjunctive hemostatic maneuver for intraoperative bleeding.

Carbon dioxide gas endoscopy of the deep gluteal space

The treatment of hip and pelvic pain associated with abnormalities of the deep gluteal space has evolved and increasingly involves endoscopic techniques with a saline expansion medium. This investigation presents a surgical technique utilizing carbon dioxide as the insufflation medium for deep gluteal space endoscopy in 17 cadaveric hips. This technique was successful in 94% (16/17) of the hips, allowing for visualization of the sciatic nerve, posterior femoral cutaneous nerve, pudendal nerve, branch of the inferior gluteal artery crossing the sciatic nerve, piriformis muscle, hamstring tendon origin, and lesser trochanter. Our experience suggests that gas expansion presents several advantages over fluid expansion.

Venous carbon dioxide embolism during laparoscopic cholecystectomy a literature review

Laparoscopy has become the procedure of choice for routine gallbladder removal. A serious complication of this technique is the occurrence of gas emboli due to insufflation. It is associated with a high mortality rate of around 28%. The present systematic review intends to provide more insight into causes, symptoms and risk factors for this specific complication and to explore which measures should be taken to treat and prevent it. The Cochrane library and Pubmed were used as sources. Articles and their references were selected when they were related to the subject in sufficient detail. The course of this complication can vary from asymptomatic up to impairment of normal flow through the right ventricle (RV) or pulmonary artery, potentially leading to acute heart failure. The severity depends on the amount of gas, the rate of accumulation and the ability to remove the gas bubbles. It is difficult to estimate the true incidence of venous gas embolism during laparoscopic cholecystectomy as there are various diagnostic tools, each with different sensitivity. Precautions that need to be taken are: correct positioning of the needle, low insufflation pressure, low insufflation speed, screening for hypovolemia, Trendelenburg positioning, availability of intervention equipment at operation table, no placement of venous catheters during inspiration and catheter removing during expiration. Physicians need to be more aware of this harmful complication and the preventative measurements that need to be taken. As there are virtually no prospective data, future studies are needed to gain more knowledge on gas emboli during laparoscopic cholecystectomy.

Cerebral air embolism following an endoscopic variceal ligation: A case report

BACKGROUND

Cerebral air embolism (CAE) is a rare but potentially devastating complication of endoscopic procedures. Only 3 cases, to our knowledge, have been reported.

CASE PRESENTATION

A 50-year-old female patient presented with hepatitis C virus-related hepatic cirrhosis, emergency endoscopy and endoscopic variceal ligation was performed in an awakened state. CAE occurred during procedure, the patient passed away the next day in the intensive care unit.

CONCLUSIONS

CAE is a rare but potentially devastating complication in endoscopic procedures. We need more preventive tools and treatments.

Endoscopic Bubble Trouble: Hyperbaric Oxygen Therapy for Cerebral Gas Embolism During Upper Endoscopy

Gas embolism is a rare but potentially devastating complication of endoscopic procedures. We describe 3 cases of gas embolism which were associated with endoscopic procedures (esophagogastroduodenoscopy and endoscopic retrograde cholangiopancreatography). We treated these at our hyperbaric medicine center with 3 different outcomes: complete resolution, death, and disability. We review the literature regarding this unusual complication of endoscopy and discuss the need for prompt identification and referral for hyperbaric oxygen therapy. Additional adjunctive therapies are also discussed.

Forensic Veterinary Pathology

Sharp-force injuries are injuries caused by a mechanical force using sharp objects against the skin. Sharp-force injuries are mainly classified as stab, incised, chop, and therapeutic wounds and are less frequent than blunt-force injuries in animals. The analysis of the edges of the wound is crucial, especially if more than one type of lesion is involved. It may be difficult to differentiate between sharp trauma and blunt trauma, because lacerations can resemble incised wounds. The accurate documentation and examination of these injuries may indicate the instrument involved, the relationship between the animal and the perpetrator, and the force of the stab. Situations in which this type of trauma occurs may involve social violence, accidents, hunting, veterinary medical management, and religious rituals. The causes of death related to this type of trauma include hypovolemic shock, pneumothorax, or asphyxiation due to aspiration of blood. Necropsy findings should provide objective and unbiased information about the cause and manner of death to aid the investigation and further judgment of a possible crime.

Computed tomography-guided percutaneous biopsy of pancreatic masses using pneumodissection

Objective To describe the technique of computed tomography-guided percutaneous biopsy of pancreatic tumors with pneumodissection. Materials and Methods In the period from June 2011 to May 2012, seven computed tomography-guided percutaneous biopsies of pancreatic tumors utilizing pneumodissection were performed in the authors' institution. All the procedures were performed with an automatic biopsy gun and coaxial system with Tru-core needles. The biopsy specimens were histologically assessed. Results In all the cases the pancreatic mass could not be directly approached by computed tomography without passing through major organs and structures. The injection of air allowed the displacement of adjacent structures and creation of a safe coaxial needle pathway toward the lesion. Biopsy was successfully performed in all the cases, yielding appropriate specimens for pathological analysis. Conclusion Pneumodissection is a safe, inexpensive and technically easy approach to perform percutaneous biopsy in selected cases where direct access to the pancreatic tumor is not feasible.

Carbon dioxide embolism during laparoscopic surgery

Clinically significant carbon dioxide embolism is a rare but potentially fatal complication of anesthesia administered during laparoscopic surgery. Its most common cause is inadvertent injection of carbon dioxide into a large vein, artery or solid organ. This error usually occurs during or shortly after insufflation of carbon dioxide into the body cavity, but may result from direct intravascular insufflation of carbon dioxide during surgery. Clinical presentation of carbon dioxide embolism ranges from asymptomatic to neurologic injury, cardiovascular collapse or even death, which is dependent on the rate and volume of carbon dioxide entrapment and the patient's condition. We reviewed extensive literature regarding carbon dioxide embolism in detail and set out to describe the complication from background to treatment. We hope that the present work will improve our understanding of carbon dioxide embolism during laparoscopic surgery.

Cholecystectomy in the presence of a large patent foramen ovale: laparoscopic or open?

An obese patient with cholelithiasis and acute cholecystitis was scheduled for an emergency laparoscopic cholecystectomy. On preoperative workup, a 5-year-old echocardiogram showed a large patent foramen ovale (PFO) with a right-to-left shunt that was open at rest. Noting both the benefits of laparoscopic surgery and the substantial incidence of PFO in the general population (10% to 30%), the attending and consulting surgeons reasoned that the benefits of laparoscopy greatly exceeded an immeasurably small risk of paradoxical emboli.

Prolonged paradoxical air embolism during intraoperative intestinal endoscopy confirmed by transesophageal echocardiography -A case report-

Venous air embolism (VAE) during intestinal endoscopy is a rare complication. We report a case of cardiovascular collapse due to VAE confirmed by transesophageal echocardiography (TEE) during intraoperative intestinal endoscopy. TEE detected air bubbles in the left ventricle up to 1 hour after the event. When a patient deteriorates during endoscopic procedures, VAE and possible paradoxical air embolism (PAE) should be suspected. This case demonstrates that TEE can play an important role in diagnosing and managing an air embolism in anesthetized patients. In addition, this case demonstrates that PAEs may occur longer than expected after recovery from VAE-induced cardiovascular collapse.

Abdominal Insufflation Decreases Blood Loss and Mortality after Porcine Liver Injury

BACKGROUND

Uncontrolled intra-abdominal bleeding is a common cause of death in trauma patients in the prehospital and perioperative settings. The detrimental effects of abdominal hypertension are well studied, but the potential therapeutic use of abdominal insufflation for hemostasis has not been fully explored. We measured the effect of abdominal insufflation on blood loss and physiologic outcomes in a swine model of blunt liver injury.

METHODS

Twenty-one anticoagulated swine (32 +/- 3 kg) were anesthesized; laparotomy was performed to localize liver anatomy and to place loose tourniquettes isolating the porta hepatis and supra/infrahepatic vena cava. A captive bolt gun was used to create a grade V hepatic laceration, producing massive parenchymal injury as well as complex tears of the middle and right hepatic veins. Animals were randomized into either control (n = 10) or abdominal insufflation at 20 cm H(2)O pressure (n = 11) groups. Crystalloid was used to maintain a mean arterial pressure of 30 mm Hg. Arterial pressure and other physiologic variables were recorded for 20 minutes. Animals were then sacrificed and blood loss measured.

RESULTS

Blood loss was 69% lower in insufflated animals compared with controls (384 +/- 51 versus 1252 +/- 88 cc, p < 0.001). After 20 minutes, insufflated animals had significantly higher mean arterial blood pressure (32.2 +/- 4.2 versus 21.2 +/- 4.0 mm Hg) and lower total resuscitation volume (195 +/- 83 versus 1356 +/- 95 cc). Three pigs died in the control group (30%), whereas no insufflated animals died (p < 0.05).

CONCLUSION

In a swine model of catastrophic blunt hepatic injury, abdominal insufflation significantly decreased blood loss and mortality.

Radiofrequency Ablation Combined with CO2Injection for Treatment of Retroperitoneal Tumor: Protecting Surrounding Organs Against Thermal Injury

OBJECTIVE

The objective of this study was to separate target tumors from adjacent structures by injecting carbon dioxide (CO2) around the tumor to avoid thermal injury and the heat-sink effect from the blood vessel during percutaneous radiofrequency ablation.

CONCLUSION

We successfully achieved complete ablation of a retroperitoneal tumor without thermal injury. Imaging-guided percutaneous CO2 injection is useful for preventing thermal injury while achieving complete ablation of the tumor during radiofrequency ablation.

Hepatic Resection by the Cavitron Ultrasonic Surgical Aspirator?? Increases the Incidence and Severity of Venous Air Embolism

The Cavitron Ultrasonic Surgical Aspirator (CUSA) is an innovative tool for resecting hepatic parenchyma, which reduces intraoperative blood loss and perioperative morbidity. We designed this study to compare the incidence and severity of venous air embolism (VAE) detected via transesophageal echocardiography (TEE) during hepatic resection by using either the clamp-crushing method or the CUSA method. Fifty patients scheduled for hepatic resection were randomly assigned to receive hepatic resection by the clamp-crushing method (CC group) or by CUSA (CUSA group). After the induction of anesthesia, the TEE probe was inserted into the patient's esophagus. An independent anesthesiologist graded VAE shown in the 4-chamber view of TEE. All patients in the CUSA group showed VAE during hepatic resection and 44% of the patients had air embolism filling more than half the right heart diameter. In CC group, 68% of the patients showed VAE, which filled less than half the right heart diameter. There were no significant differences in hemodynamics and end-tidal CO2 partial pressure between the two groups. In conclusion, hepatic resection by CUSA increases the incidence and severity of VAE.

IMPLICATIONS

This study demonstrated that venous air embolism during hepatic resection was more frequent and severe when using the Cavitron Ultrasonic Surgical Aspirator. Although we found no evidence of hemodynamic compromise, increased venous air embolism may increase the risk of paradoxical embolism in patients with liver cirrhosis.

Undiagnosed aorto-caval fistula during total laparoscopic abdominal aortic aneurysm repair: a cause of conversion

Total laparoscopic aortic repair is evolving and is now the technique of choice for the treatment of infrarenal abdominal aortic aneurysms (AAA) in our department. With growing experience, surgeons will be confronted with the same peroperative situations than open surgery. We report a case of total laparoscopic AAA repair with peroperative diagnosis of aorto-caval fistula (ACF).

Improved cerebral protection through replacement of residual intracavital air by carbon dioxide: a porcine model using diffusion-weighted magnetic resonance imaging

BACKGROUND

Major risk of central or peripheral organ damage is attributed to air embolism from incompletely de-aired cardiac chambers after cardiac operations. Replacement of air by carbon dioxide insufflation into the thoracic cavity is widely used. Diffusion-weighted magnetic resonance imaging of the brain detects ischemia within minutes after onset. The reversibility of ischemia in cerebral tissue after massive gaseous emboli has not yet been described.

METHODS

After selective catheterization of a common carotid artery in 15 pigs, boli of 1 mL/kg body weight of air (n = 5) or carbon dioxide (n = 5, "low dose") were applied. Five pigs received 2 mL/kg body weight of carbon dioxide ("high dose"). Diffusion-weighted magnetic resonance imaging of the brain was performed 2, 5, 10, 15, and 25 minutes after embolization.

RESULTS

All animals of the "air" group showed important circulatory reactions leading to death of 2 animals. In the whole group, diffusion-weighted magnetic resonance imaging revealed irreversible hyperintense signals in both hemispheres. In the low-dose group, no change in signal intensity was observed in 2 pigs, and 3 others showed reversible changes in signal intensity, without important circulatory reactions. In 3 animals of the high-dose group, hyperintense signals were reversible, but 2 others presented with bilateral, irreversible signals in diffusion-weighted magnetic resonance imaging, accompanied by minor circulatory reactions.

CONCLUSION

In contrast to the dramatic effect of air emboli, identical quantities of carbon dioxide injected into cerebral arteries of the pigs were not associated with major clinical symptoms. The early reversibility of ischemic reactions visualized in diffusion-weighted magnetic resonance imaging encourages the use of carbon dioxide insufflation as a protective method in cardiac surgery.

Massive pulmonary embolism presented as sudden cardiac arrest in the immediate postoperative period after laparoscopic hysterectomy

A rare case of postoperative cardiac arrest in an otherwise healthy, 49-year-old female patient who had a laparoscopic hysterectomy, is presented. The cause of cardiac arrest was due to massive pulmonary embolism, which was detected by transesophageal echocardiography. Laparoscopic surgery is regarded as a less invasive procedure and provides a lower risk for postoperative complications. However, our is a case reminer that pneumoperitoneum may interfere with venous flow of lower extremities and predispose one to deep vein thrombosis or pulmonary embolism.

Abdominal insufflation for prevention of exsanguination

BACKGROUND

Currently, traumatic intra-abdominal hemorrhage continues unchecked during transport and triage, and a simple technique of prehospital hemostasis might improve outcomes. The hemostatic effect of abdominal hypertension has not been studied.

PURPOSE

To examine the effect of iatrogenic abdominal insufflation on blood loss and hemodynamic performance after major abdominal vascular injury.

METHODS

Following laparotomy, a 2.7 mm hole was created in the inferior vena cava of 10 anticoagulated pigs and controlled with a partially occlusive, laparoscopic vascular clamp. After abdominal closure the clamp was released and the pig was randomized to either control (n = 5) or immediate abdominal CO2 insufflation at 20 cm H2O pressure (n = 5). Lactated Ringer's solution was used as needed to maintain a mean arterial pressure of 60 mm Hg. After 15 minutes of hemorrhage and hemodynamic monitoring, the animals were killed and blood loss measured. Mean blood loss was compared between groups using the Student test, as were final values for physiologic variables. Temporal changes in physiologic parameters were compared using analysis of variance.

RESULTS

Mean blood loss was reduced by 61% in insufflated pigs versus controls (695 +/- 244 versus 1764 +/- 328 cc, p < 0.001). Compared with controls, insufflated pigs had significantly higher mean arterial pressure (64 versus 25 mm Hg, p < 0.001), end-tidal CO2 (40.8 versus 17.8 mm Hg, p < 0.001), and pulmonary capillary wedge pressure (10.2 versus 5.8 mm Hg, p = 0.026) immediately before the pigs were killed.

CONCLUSION

Iatrogenic abdominal insufflation significantly decreased blood loss and improved hemodynamics in a porcine model of traumatic venous hemorrhage. Iatrogenic abdominal insufflation may be useful in the prehospital management of abdominal injury.

Transoesophageal echocardiography shows high risk of gas embolism during laparoscopic hepatic resection under carbon dioxide pneumoperitoneum

BACKGROUND

The ultrasonically activated scalpel (UAS) enables safe and effective laparoscopic tissue dissection, making hepatic resection feasible. This study compared blood loss and risk of gas embolism using the UAS during open hepatic resection and laparoscopic hepatic resection.

METHODS

Female pigs were divided into two groups for laparoscopic (n = 7) and open (n = 5) left hepatic lobectomy. The UAS was used for both tissue cutting and coagulation. Laparoscopic liver resection was performed under carbon dioxide pneumoperitoneum (intraperitoneal pressure 12 mmHg). During surgery animals were monitored haemodynamically by an arterial line and Swan-Ganz catheter. Two-dimensional transoesophageal echocardiography (2D-TEE) was used to detect gas emboli with special attention to the right atrium and ventricle. Gas emboli were graded according to size, and correlated with haemodynamic and blood gas data.

RESULTS

During open and laparoscopic hepatic resection the UAS resulted in minimal blood loss and effective tissue dissection. No air embolism was seen during open surgery. With laparoscopic hepatic resection 2D-TEE revealed gas embolism in all animals. Gas embolism was accompanied by cardiac arrhythmia in four of seven animals. No direct correlation was observed between embolism episodes and blood gas variables. There were no deaths after episodes of embolization. A significant decrease in arterial partial pressure of oxygen was seen at the end of the laparoscopic procedure in all animals.

CONCLUSION

The UAS causes minimal blood loss during both open and laparoscopic hepatic resection. Laparoscopic liver dissection under carbon dioxide pneumoperitoneum carries a high risk of gas embolism.

Venous air and gas emboli in operative hysteroscopy

Air and gas emboli have been reported in almost all areas of clinical and surgical practice. The literature is replete with observations and methods for treating these events. It is possible to mitigate the consequences of this risk, particularly in operative hysteroscopy. Recommendations include monitoring devices such as capnography to facilitate intraoperative diagnosis of these emboli.

Laparoscopic renal autotransplantation

BACKGROUND AND PURPOSE

Renal autotransplantation is an extensive open surgical operation consisting of two distinct procedures, live-donor nephrectomy and autotransplantation, and requiring two large skin incisions. Herein, we analyze the feasibility of performing the entire procedure laparoscopically.

MATERIALS AND METHODS

Renal autotransplantation was performed entirely laparoscopically in six female farm pigs. Following a left donor nephrectomy, intracorporeal renal hypothermia was achieved by intra-arterial perfusion of ice-cold solution through a 4F balloon catheter. During autotransplantation, the renal vessels were anastomosed intracorporeally to the previously prepared ipsilateral common iliac vessels in an end-to-side fashion. Laparoscopic freehand suturing (5-0 Prolene) and knot-tying techniques were employed exclusively. A staged contralateral native nephrectomy was performed in five animals. Postoperative follow-up included serial creatinine measurements, intravenous urography, aortography, and renal histologic examination.

RESULTS

The mean operating time was 6.2 hours (range 5.3-7.9 hours), the venous anastomosis time was 33 minutes (range 22-46 minutes), the arterial anastomosis time was 31 minutes (range 27-35 minutes), and the total iliac clamping time was 77 minutes (range 62-88 minutes). The total renal ischemia time was 68.7 minutes: warm ischemia 5.1 minutes, cold ischemia 33 minutes and rewarming 31 minutes. Serum creatinine concentrations remained stable: baseline 1.3 mg/dL, after autotransplantation 1.1 mg/dL, and after contralateral nephrectomy 1.6 mg/dL. Intravenous urography and aortography prior to euthanasia (N = 5) demonstrated prompt contrast uptake and excretion by the autotransplanted kidneys and patent arterial anastomoses, respectively. Histopathologic examination of the autograft demonstrated normal renal architecture.

CONCLUSIONS

Renal autotransplantation can be performed utilizing laparoscopic techniques exclusively. This study may form the basis for performance of complex urologic vascular procedures laparoscopically.

Laparoscopic aortorenal bypass

BACKGROUND AND PURPOSE

Open surgical renovascular repair, although producing excellent results, confers significant operative morbidity. As a result, less morbid procedures such as percutaneous balloon angioplasty and stenting have gained increasing acceptance. Laparoscopic techniques have not previously been applied to renal revascularization. The aim of this study was to demonstrate the technical feasibility and the long-term clinical and pathologic outcomes of laparoscopic aorto-left renal artery bypass in a chronic porcine model.

MATERIALS AND METHODS

Eight animals were used in the study. All laparoscopic suturing and knot-tying were performed intracorporeally using free-hand techniques. The following operative steps were employed: (1) aortic dissection and cross-clamping; (2) transection and refashioning of the left renal artery ostium; (3) in-situ renal hypothermia; (4) end-to-side aorto-left renal artery anastomosis; and (5) aortic unclamping. In situ renal hypothermia was achieved laparoscopically by infusion of ice-cold heparinized saline into the renal artery through a balloon catheter.

RESULTS

All eight pigs underwent laparoscopic aortorenal bypass successfully. The median surgical time was 110 minutes, and the aortic cross-clamping time was 45.5 minutes. The median anastomotic time was 40 minutes, and the renal warm ischemia time was 9 minutes. The median estimated blood loss was 30 mL. An intraoperative complication of suture breakage leading to anastomotic hemorrhage occurred in one animal; the problem was corrected laparoscopically. Postoperatively, one animal died from pneumonia. The remaining seven animals experienced no postoperative complications and were euthanized, one each at postoperative day 0 and 1 and week 1, 2, 3, 4, and 6. The median preoperative and postoperative (at euthanasia) serum creatinine values (1.15 mg/dL v 1.2 mg/dL; P = 0.39) were similar. However, compared with preoperative peripheral renin activity (0.25 microg/L per hour), the postoperative peripheral renin activity was elevated (0.9 microg/L per hour; P = 0.047). Autopsy revealed a grossly normal left kidney, with Doppler confirmation of flow in the repaired renal artery in all seven animals. Ex vivo angiography confirmed a patent anastomosis. On histopathology examination, the early left renal parenchymal specimens revealed transient, mild acute tubular necrosis that resolved over sequential specimens without significant long-term sequelae. Histologic analysis of the aorto-left renal artery anastomotic site revealed gradual endothelialization with time.

CONCLUSIONS

Laparoscopic aortorenal artery revascularization is technically feasible. Our chronic animal model has demonstrated durable success over a 6-week follow-up. This study represents the initial report in the literature.

Newly designed retraction devices for intestine control during laparoscopic aortic surgery: a comparative study in an animal model

BACKGROUND

Recent clinical studies have demonstrated the feasibility of laparoscopic surgery for aortic occlusive and aneurysmal disease. However, transperitoneal aortic access is compromised by poor exposure in the operative field from uncontrolled bowel. The retractors that are currently available are inadequate for this task. The development of new retractors would help to facilitate laparoscopic aortic surgery.

METHODS

Six female piglets (28-30 kg) in each group underwent laparoscopy with pneumoperitoneum (12 mmHg). Exposure of the infrarenal aorta and cross-clamping were undertaken through a transperitoneal approach. Two paddles inserted in a polyester bilayer (mobile device, group A) or a mesh net fixed to the abdominal wall (fixed device, group B) were used to retain the bowel. Aortotomy and suturing were performed to mimic a vascular procedure. After bleeding was controlled, the intraabdominal pressure (IAP) was lowered to 6 mmHg, and retraction was assessed for 30 min. The main outcome measures were time to deploy the retractors, time to perform the vascular procedure, time to withdraw the devices, and total procedural time. Blood loss and frequency of retraction failure were also recorded.

RESULTS

Mean time to deploy the device was 22 +/- 12 min in group A and 36 +/- 34 min in group B (n.s.). Vascular surgery time averaged 60 +/- 24 min in group A and 68 +/- 16 min in group B (n.s.). The times to withdraw the nets were 3.6 +/- 1.2 min and 13.5 +/- 8.2 min, respectively (p < 0.05). Total surgery time was 155 +/- 41 min vs 174 +/- 49 min (n.s.). There were six retraction failures, five in group A and one in group B. When lower IAP was used, there was only one failure in each study group. Mean blood loss was <150 ml in both groups. There were no major complications.

CONCLUSIONS

Both methods provided adequate exposure of the infrarenal aorta. Vascular surgery time and blood loss were similar for both groups. The movable device proved more usable and, at lower IAP, more effective. The results of this study demonstrate effective bowel retraction for laparoscopic aortic surgery.

Transesophageal echocardiographic detection of gas embolism and cardiac valvular dysfunction during laparoscopic nephrectomy

We used transesophageal echocardiography (TEE) to monitor venous gas embolism, cardiac performance, and the hemodynamic effects of positioning and pneumoperitoneum in 16 healthy kidney donors undergoing laparoscopic nephrectomy. A four-chamber view was used continuously, except at predetermined intervals, when a complete TEE examination for cardiac function was performed. Other clinical variables recorded include systolic, diastolic, and mean arterial blood pressure; heart rate (HR), pulse oximetric saturations; and end-tidal CO2. Baseline valvular incompetence was seen in 13 of the 16 patients when supine and asleep. After positioning for surgery and induction of pneumoperitoneum, TEE revealed valvular incompetence with regurgitation more pronounced from baseline in 15 of the 16 patients. In one patient, during renal vein dissection, gas entered the right atrium from the inferior vena cava, worsening tricuspid regurgitation. Hemodynamic variables and ejection fraction were tested by using repeated-measures analysis of variance for significance (P < 0.05). Pneumoperitoneum increased (P < 0.05) systolic blood pressure (from 102.8 +/- 3.89 to 120.8 +/- 3.88 mm Hg) and HR (from 68.9 +/- 3.19 to 75.6 +/- 2.62). Ejection fraction was unchanged. The high incidence of valvular incompetence indicates that further studies are needed to assess these effects during laparoscopic nephrectomy with cardiac disease.

IMPLICATIONS

Laparoscopic surgery has gained popularity as a procedure for the removal of donated kidneys. Although the insufflation of gas necessary for this relatively simple approach poses a low risk of venous air embolism, it may increase the risk of changes in valvular competency.

Videoendoscopic thoracic aorta-to-femoral artery bypass. A feasibility study in a canine model

PURPOSE

This study was undertaken to determine whether videoendoscopic thoracic aorta-to-femoral artery bypass is a technically feasible operation.

METHODS

An acute canine study involving five mongrel dogs was carried out. After the dogs had been given a general anesthetic, the femoral arteries were exposed in the traditional fashion. On the left side, a retroperitoneal, retrorenal tunnel was extended from the common femoral artery to the diaphragm. Under videoendoscopic control, the tunnel was opened through the posterior thoracic attachments of the diaphragm into the thoracic cavity. A Dacron graft was tunneled from the thoracic cavity on the left to the left groin. The thoracic aorta was controlled with a side-biting clamp, and an endoscopically performed end graft-to-side thoracic aortic anastomosis was created. After completion of the thoracic anastomosis, the left femoral anastomosis was created in a traditional manner. A left-to-right femoral bypass completed the lower extremity vascular procedure. An open thoracotomy was avoided.

RESULTS

Videoendoscopic thoracic aorta-to-femoral artery bypass was successfully performed in all five animals. All components of the thoracic procedure, including exposure, dissection, vessel control, cross-clamping, and anastomosis, were performed through the thoracic ports with conventional laparoscopic instruments. Blood loss was minimal. All animals survived the procedure before being killed.

CONCLUSION

Videoendoscopic thoracic aorta-to-femoral artery bypass is a technically feasible operation in a canine model. Advantages of this unique approach over the experimental laparoscopic and the traditional transperitoneal open aortofemoral bypass include ease of aortic exposure, ability to control a segment of disease-free aorta, and anastomosis in a disease-free segment of aorta. Potential advantages include decreased perioperative morbidity rates with the videoendoscopic approach. Before there is clinical consideration of this surgical approach, long-term experiments are required to demonstrate the safety of the procedure.

Factors involved in gas embolism after laparoscopic injury to inferior vena cava

This study evaluated the incidence and factors involved in the occurrence of gas embolism after laparoscopic injuries. A 5-MHz transesophageal echocardiographic (TEE) probe was placed in 11 anesthetized pigs and used to examine the right cardiac chambers and pulmonary artery. A calibrated carbon dioxide analyzer continuously measured end-tidal carbon dioxide (ETCO2). The ventilatory settings were adjusted to achieve a baseline ETCO2 between 25 and 28 mm Hg. A blinded dose-response curve for TEE and ETCO2 measurements were created by injecting 0.0007 to 1.5 mL/kg of CO2 gas intravenously. Venotomies (N = 22) were created laparoscopically in the inferior vena cava (IVC) of the study animals. All TEE images were videotaped and correlated with laparoscopic events. Embolic episodes were classified by comparison with images recorded during the bolus studies. A variety of methods for obtaining hemostasis and repairing the venotomies were evaluated and their effects on gas embolism were studied. No emboli were noted when the venotomies were bleeding freely, the hole was directly occluded, or the proximal IVC was compressed. Marked embolism was seen with distal IVC occlusion or when there had been significant blood loss. In this situation, manipulation of the hole and higher intraperitoneal pressures led to higher degrees of embolization. No emboli were seen in an open control group except after significant bleeding. The TEE is the most sensitive method of detecting gas emboli; however, the majority of episodes are not clinically significant. Embolism of CO2 occurs when central venous pressure is decreased by blood loss or distal compression. When significant venous bleeding occurs, intravascular volume should be maintained and the bleeding site should be directly occluded.