Magnesium sulphate and (123)I-MIBG in pheochromocytoma: Two useful techniques for a complicated disease

Pheochromocytoma is a tumour of the chromaffin tissue. It may, through catecholamine release, have deleterious effects on myocardial structure. A 48-year-old woman with a history of hypertension and type II diabetes mellitus (ASA II) was diagnosed of pheochromocytoma-induced myocarditis, which caused severe cardiogenic shock, with an ejection fraction of 20%. Extreme blood pressure swings required aggressive therapy with vasoactive drugs (norepinephrine and dopamine) and an intra-aortic balloon pump, despite which severe haemodynamic instability persisted. Finally, the use of magnesium sulphate allowed for cardiovascular stabilization and weaning off vasoactive drugs prior to surgery. (123)I-metaiodobenzylguanidine scintigraphy helps not only to functionally confirm tumour tissue, but also to assess severity and prognosis of cardiac failure. Prognosis of pheochromocytoma-induced heart failure can be very poor. The use of these two well-known and relatively simple 'tools' for treatment and prognosis is a helpful option to keep in mind.

Liver transplantation in high-risk patients: hepatopulmonary syndrome and portopulmonary hypertension

Two pulmonary vascular disorders, considered mutually exclusive, may be present in candidates for orthotopic liver transplantation (OLT). On the one hand, hepatopulmonary syndrome (HPS), with a prevalence about 20% in end-stage liver disease, is characterized by pulmonary vascular dilatation and abnormal gas exchange. On the other hand, portopulmonary hypertension (POPH), a process defined by pulmonary hypertension associated with portal hypertension, is less common than HPS (4%). These entities have very distinct clinical implications; whereas HPS is clinically characterized by respiratory symptoms that evolve to severe hypoxemia, patients with POPH are commonly asymptomatic, frequently diagnosed in the setting of OLT, and the symptoms appear when there is hemodynamic compromise. The pathogenesis of both entities is a putative mechanism, the imbalance of vasoactive substances in pulmonary vessels. The role of OLT to reverse these vascular disorders is controversial, although complete resolution of HPS and, less frequently, POPH following OLT has been reported. The recognition that the presence of both HPS and POPH is an important cause of morbidity and mortality among recipients of OLT has resulted in a change in the policy to select OLT candidates. Accurate identification of patients with pulmonary vascular disorders associated with liver disease should be the first step in the management of OLT candidates. Because the determinants of the prognosis of OLT in the setting of these pulmonary vascular changes have not been well established, an accurate cardiopulmonary evaluation with careful assessment of pulmonary gas exchange (in HPS) and right ventricular function (in POPH) of potential OLT recipients is mandatory before the procedure.

The effects of vasoactive drugs on hepatic blood flow changes induced by CO2 laparoscopy: an animal study

Laparoscopic surgery is associated with systemic and splanchnic hemodynamic alterations. Recent data suggest that small-dose dobutamine may attenuate the reduction in splanchnic blood flow associated with increments in intraabdominal pressure. We conducted this study to analyze the effects of dopamine and dobutamine on the hepatic circulation in this setting. Twenty-one pigs were anesthetized and mechanically ventilated. A flow-directed pulmonary artery and carotid artery catheters were inserted. Perivascular flow probes were placed around the main hepatic artery and the portal vein. CO2 was insufflated into the peritoneal cavity to reach an intraabdominal pressure of 15 mm Hg. After 60 min, animals received dopamine (5 microg x kg(-1) x min(-1); n = 8), dobutamine (5 microg x kg(-1) x min(-1); n = 8), or saline (n = 5) for 30 min. Pneumoperitoneum induced significant increases in heart rate, mean arterial pressure, and systemic vascular resistance, with decreases in cardiac output and hepatic artery and portal vein blood flows. Dobutamine infusion, in contrast to dopamine, corrected, at least in part, cardiac output, systemic vascular resistance, and hepatic artery blood flow alterations, but neither drug restored total hepatic blood flow.

IMPLICATIONS

Hepatic blood flow decreases during laparoscopic surgery. A small-dose infusion of neither dobutamine nor dopamine corrects the total hepatic blood flow impairment, but the former is able to restore the hepatic arterial blood supply in an animal model mimicking this condition.

Dobutamine restores intestinal mucosal blood flow in a porcine model of intra-abdominal hyperpressure

OBJECTIVE

To assess the effects of dopamine and dobutamine administration on the systemic and mesenteric (macro- and microvascular) circulatory disturbances induced by intra-abdominal hyperpressure.

DESIGN

Prospective, randomized study.

SETTING

Animal research laboratory in a university hospital.

SUBJECTS

Twenty-five pigs of either gender, weighing 30-35 kg.

INTERVENTIONS

Animals were anesthetized, and their lungs were mechanically ventilated. Pulmonary artery flotation and carotid artery catheters were inserted for hemodynamic monitoring and blood sampling. A perivascular flow probe was placed around the superior mesenteric artery, and a laser Doppler probe was positioned in the lumen of the ileum to measure arterial and intestinal mucosal blood flows, respectively. CO2 was insufflated into the peritoneal cavity to reach an intra-abdominal pressure of 15 mm Hg, and 60 mins later, animals received dopamine (5 microg/kg/min; n = 10), dobutamine (5 microg/kg/min; n = 10), or saline (n = 5) for 30 mins.

MEASUREMENTS AND MAIN RESULTS

Peritoneal CO2 insufflation induced significant increases in heart rate, arterial pressure, and systemic vascular resistance with concomitant decreases in cardiac output and superior mesenteric arterial and intestinal mucosal blood flows. Although dobutamine infusion reversed the decrease in cardiac output, it failed to restore superior mesenteric artery blood flow; however, intestinal mucosal blood flow returned to baseline levels. Dopamine also attenuated the decrease in cardiac output, but it had no beneficial effect on splanchnic hemodynamic variables.

CONCLUSIONS

Low-dose infusion of dobutamine, but not dopamine, corrects the intestinal mucosal perfusion impairment induced by moderate increases in intra-abdominal pressure.

Severe portopulmonary hypertension after liver transplantation in a patient with preexisting hepatopulmonary syndrome

BACKGROUND

Portopulmonary hypertension and hepatopulmonary syndrome have been considered mutually exclusive pulmonary vascular disorders in liver disease states.

METHODS

This current report describes a middle-aged patient, a candidate for liver transplantation, diagnosed with hepatopulmonary syndrome on the basis of clinical, echocardiographic and gas exchange criteria. Unusually high pulmonary pressures were observed at liver transplantation, performed 6 months after the initial diagnosis of hepatopulmonary syndrome. Three months later, the patient developed severe pulmonary hypertension and died of right ventricular failure during a second attempted liver transplantation. Postmortem histologic findings in the lung confirmed the presence of plexogenic pulmonary arteriopathy.

CONCLUSION

This case illustrates the potential occurrence of hepatopulmonary syndrome and portopulmonary hypertension in the same patient, suggesting that the presence of hepatopulmonary syndrome may not preclude the development of portopulmonary hypertension.

[Continuous epidural perfusion with meperidine on demand for the treatment of postoperative pain]

OBJECTIVE

To determine whether epidural administration of meperidine through a system affording patient-controlled analgesia (PCA) is appropriate for postoperative pain.

PATIENTS AND METHODS

A prospective double-blind study of 30 patients undergoing high abdominal surgery randomly into two groups. After surgery with the same type of general anesthesia for both groups, group A received epidural meperidine through a PCA pump (initial boluses of 50 mg + infusion of 10 mg/h with additional doses of 25 mg upon patient demand and closure time of 90 min). Control group B received 0.9% saline serum through an epidural PCA system with identical perfusion characteristics. All patients had access to additional analgesia with subcutaneous meperidine (1 mg/kg weight).

RESULTS

There was a wide interindividual variation in meperidine consumption in group A, with a mean total dose of 301.4 +/- 73 mg in 24 hours and no patient requiring additional subcutaneous meperidine. Subcutaneous meperidine required in group B reached 273 +/- 65.8 mg in 24 hours, with no significant differences between groups A and B for total dose given. No side effects inherent to the technique were found. Sufficient control of pain was achieved for all patients receiving epidural meperidine.

CONCLUSIONS

Epidurally administered PCA with meperidine affords better pain relief with greater patient satisfaction than the same amount of drug given subcutaneously in successive doses upon patient request.