M.C. Bellamy

Dopexamine and microcirculatory flow in transplanted small bowel: the Leeds experience.

Abstract Intestinal mucosa is extremely vulnerable to ischemic injury. In transplanted small bowel, this may represent preservation, ischemia-reperfusion injury, technical errors, postimplantation ischemia, or rejection. Such injury may compromise the mucosal barrier. Barrier dysfunction can lead to bacterial translocation and endotoxemia, a trigger for multisystem organ failure (MSOF). Prevention of further ischemic injury in the postoperative period by maintaining optimal graft perfusion may have a major role to play in ensuring graft viability. Previous methods of monitoring graft function have included clinical assessment, serum procoagulant levels, serial endoscopy and mucosal biopsy, and intestinal permeability studies. These methods are not ideal for monitoring early graft function. A number of noninvasive measures of graft perfusion are now available. These include laser Doppler flowmetry (LDF) and gut tonometry. Neither of these techniques has been applied to the transplanted small bowel. LDF is easy to use, is noninvasive, allows continuous monitoring, and its use has been validated in orthotopic liver transplantation (OLT) and in postoperative monitoring of new grafts. Gut tonometry was designed to allow measurement of bowel intramucosal pH (pHi). Low intestinal pH indicates splanchnic hypoperfusion or anaerobic metabolism, is common in critical illness, and is associated with increased morbidity and mortality after major surgery and trauma. Gastric tonometry has been used to monitor early graft function in OLT. Both techniques enable evaluation both of graft function and of therapies aimed at improving perfusion. The pharmacologic profile of dopexamine suggests it would prove a valuable agent in improving splanchnic blood flow. It is a dopamine (DA) analog with action at β2 adrenoceptors and DA1 receptors and only moderate activity at β1 and DA2 receptors. Dopexamine possesses no direct α-adrenoceptor activity, but norepinephrine reuptake is inhibited. Dopexamine improves cardiac performance by vasodilatation and mild isotropic activity. These hemodynamic effects are achieved without increased myocardial oxygen consumption. Dopexamine has been shown to improve splanchnic oxygenation, an effect which appears to be independent of its systemic effects. Boyd et al have shown that deliberately increasing oxygen delivery perioperatively significantly reduces mortality and morbidity in high-risk surgical patients. We have therefore studied the effects of dopexamine on gut mucosal blood flow following small bowel transplantation, using LDF and gastric tonometry.

Alternative techniques for arterialization in multivisceral grafting.

Abstract For a small group of carefully selected patients, multivisceral grafting is a viable treatment. While early data suggest that the 3-year survival is less than 50%, 1 it is unlikely that any of these patients would have survived without transplantation. While improving results rely on advances in management, particularly in technique and immunosuppression, it is essential that the acquisition of the multivisceral graft does not compromise the procurement of the donor kidneys for transplantation. Described techniques generally employ the use of an aortic conduit or large aortic patch, 2,3 but these techniques have a number of drawbacks. For example, the use of the aortic conduit compromises the aortic patch around the orifices of the donor renal arteries which is a particular problem if there are multiple renal arteries. In addition, these techniques require mobilization of a long length of recipient aorta, often appear cumbersome, and can be difficult to orientate satisfactorily. In addition, the thoracic aorta needs to have the multiple intercostal arteries oversewn. If an aortic patch bearing the origins of the celiac and superior mesenteric arteries is used, the short length of vessels can make the anastomosis of the patch to recipient aorta difficult and hazardous.

Severe air embolism resulting from a perforated cap on a high-flow three-way stopcock connected to a central venous catheter.

EDITOR: Case Report: A 41-yr-old white male, body mass index (BMI) 18, presented with a cholangiocarcinoma invading locally into the portal vein and was scheduled for an extended right hemi-hepatectomy. As part of the anaesthetic technique, a Certofix Quinto central venous line (B Braun, Melsungen, Germany) was inserted into the right internal jugular vein under ultrasound guidance. A Smiths SC-3 high flow three-way stopcock (Smith’s Medical, Rockland, MA, USA) was attached to the 12 g lumen of the central venous catheter (CVC) and to a Level 1 rapid infuser. The surgery proceeded for a period of 2 h at which point the tumour was found to be technically unresectable and the procedure was therefore abandoned. The patient was woken up and extubated in theatre and found to be comfortable with a good working thoracic epidural. Once awake, the patient was transferred to the post anaesthetic care unit (PACU) where his care was handed over to the recovery staff. One hour later, a distress call was received from the PACU. The nursing staff had turned the patient to make him more comfortable, immediately after which he had complained of severe chest pain and had become acutely hypoxic. On review, he was clearly very distressed, gasping and had a grayish appearance. Examination showed a rapid respiratory rate, central cyanosis and a pulse oximeter reading of 80% saturation, despite receiving high-flow oxygen through a non-rebreathing system. Air entry was bilaterally equal and the breath sounds were normal. The lungs were resonant to percussion throughout. The heart rate (HR) was 130 beats min21 and blood pressure (BP) 65/30 mmHg. Heart sounds S1 and S2 were heard along with a loud ‘machinery’ murmur. Further inspection showed that the intravenous (i.v.) fluids had been disconnected from the central venous line during the turning of the patient. The three-way stopcock was open to the patient and closed to the distal position. The intermediate position was ‘sealed’ with the manufacturer’s cap. The manufacturer’s cap, in fact, has a patent lumen (Fig. 1). Air was clearly visible within the central venous line. The patient was immediately placed head down in the left lateral position and the line aspirated with a 50 mL syringe. Approximately 100 mL of a frothy mix of air and blood were aspirated to a dramatic effect. The pulse oximeter reading rapidly rose to 97% and a rapid improvement in BP was observed. The patient described feeling better almost immediately. The manufacturer’s cap was replaced with a sealed bung and a critical incident form completed. The patient made an uneventful recovery. Gas embolism (also known as air embolism) is a well-described, potentially fatal, iatrogenic clinical problem [1]. It refers to the ingress of gas, most commonly air, into the vascular system. This can result in a venous air embolus (VAE), as in our case report, an arterial air embolus or a paradoxical air embolus. Since the earliest reports of VAE, dating back to 1947 [2], one of the most common factors implicated in the cause of VAE is the CVC. Reports range from cases of fatal gas embolism due to accidental disconnection of the CVC [3] to cases of acute gas embolism on removal of the CVC [4]. We could, however, find no reports of gas embolism resulting from bungs or caps manufactured with perforated lumens and connected to the intravascular equipment.