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OBJECTIVE: To establish the efficacy of the phosphodiesterase inhibitor milrinone in facilitating weaning from cardiopulmonary bypass of high-risk patients with left ventricular dysfunction and/or pulmonary hypertension. DESIGN: A double-blinded, placebo-controlled longitudinal study. SETTING: A university teaching hospital. PARTICIPANTS: Thirty-two patients with preoperative left ventricular ejection fraction < or = 35% and/or mean pulmonary artery pressure > or = 20 mmHg were studied after their written informed consent. INTERVENTION: Patients were randomized to commence either intravenous milrinone, 50 micrograms/kg loading dose over 20 minutes followed by 0.5 microgram/kg/min infusion, or matching placebo 15 minutes before withdrawal of cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: Two patients were withdrawn from the study and their results not analyzed: one because of early failure of hemodynamic monitoring and the other because of gross surgical bleeding. In the remaining 30 patients, who were well matched for clinical and baseline hemodynamic variables, bypass support was successfully withdrawn in all 15 patients randomized to receive milrinone but in only 5 of the 15 patients randomized to receive placebo. In the 10 patients who initially failed to wean from bypass while on placebo, bypass was reinstituted and open-label milrinone was administered in the dose outlined. After treatment with open-label milrinone, these patients could also be withdrawn from bypass support. During the period of hemodynamic monitoring, cardiac index increased in both milrinone- and placebo-treated patients, although this change was greater in those treated with milrinone. Perhaps related to routine clinical treatment, there were no significant differences between the two groups with mean pulmonary artery or pulmonary capillary wedge pressures, the other major hemodynamic endpoints. There were no significant adverse effects related to milrinone. CONCLUSIONS: This placebo-controlled, double-blind study has conclusively demonstrated the benefits of milrinone in facilitating weaning of high-risk patients from cardiopulmonary bypass.

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Milrinone is an inotropic drug with vasodilator activity that has been shown to be useful in increasing cardiac output and decreasing wedge pressure. Despite these advantages, it is unknown whether this drug can be used for the treatment of perioperative spasm of coronary bypass grafts. This study was undertaken to investigate the in vitro vascular effect of milrinone on internal thoracic arteries obtained from patients undergoing coronary artery bypass grafting. The results showed that milrinone produced a potent, concentration-dependent, preventive effect on the norepinephrine-induced contraction of internal thoracic arteries, as well as reversing contraction of internal thoracic arteries by receptor-dependent agents, including the thromboxane A2 mimetic U46619, the vasoconstrictor peptide endothelin-1, and the alpha1-adrenal receptor agonist phenylephrine. The relaxing effect of milrinone was weaker, however, on internal thoracic arteries contracted with 25 mmol/L potassium chloride. Comparison of milrinone with other vasodilators, including papaverine, nitroprusside, and glyceryl trinitrate, showed milrinone to be more potent than papaverine but less potent than nitroprusside and glyceryl trinitrate. The inhibitory effect of milrinone on internal thoracic artery contraction appeared as a reduction in contractile force, not as an increase in the values of concentrations of the agonists causing 50% maximal contraction, which indicates that milrinone exerts its vasodilator effect directly on the smooth muscles, not on the membrane receptors. The results also showed no significant difference in relaxing effect between internal thoracic artery rings with and without endothelium. In conclusion, this study provides experimental evidence that milrinone is a potent, endothelium-independent, direct vasodilator of the human internal thoracic artery and provides the scientific rationale for a future clinical trial with this drug for the perioperative treatment of internal thoracic artery spasm in cardiac surgical patients.

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Feeding of large and small colonies of Plumatella repens was assessed under two flow conditions. Large colonies ingested greater numbers of particles than small colonies and feeding of colonies of both sizes increased with flow. However, the rate of increase depended on colony size. Small colonies increased feeding to a greater degree than large colonies. Mechanisms that may explain these patterns are discussed. These results contrast with an earlier study of feeding in a freshwater bryozoan. The conflicting results may reflect experimental conditions. In the previous study a small volume of still water likely entailed greater food depletion by large colonies. In our study food depletion did not occur and ambient flow carried away filtered water. We discuss how the relatively large, U-shaped lophophores of freshwater bryozoans function to produce powerful feeding currents that are suited to feeding in lotic and lentic habitats.

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Forty-four patients undergoing coronary artery surgery were allocated randomly to receive an infusion of propofol or methohexitone as a hypnotic supplement to a fentanyl-based anaesthetic technique. A taped message was played to the patients, consisting of 10 words associated with prompt sentences and a suggestion for a specific postoperative behavioural response. Twenty patients (10 propofol and 10 methohexitone) (perioperative group) were exposed to the taped message during surgery and in the immediate postoperative period and the other 24 patients (postoperative group) were exposed to the tape only in the postoperative period, after return to the intensive care unit (ICU). No patient had explicit recall of any events during the period when the tape was played. The patients in the propofol group who heard the tape during surgery had significant implicit recall of the word associations compared with the equivalent 10 methohexitone patients (P = 0.004), when tested 48 h after surgery. The patients who were played the tape whilst receiving identical infusion regimens for sedation in the ICU did not demonstrate implicit recall of the word associations in either the propofol or the methohexitone groups. There was no evidence of a response to the specific behavioural suggestion during the postoperative interview. The results confirm that auditory perception can occur during clinically adequate anaesthesia, and that suppression of auditory awareness or learning is a function of both the pharmacological degree of sedation and the degree of surgical stimulation.

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Traumatic spinal injury is an ongoing community problem. Anatomical stability of the cervical spine depends on the integrity of the bony and ligamentous structures forming the cervical spine. Such stabilising structures are divided into two groups. These are designated anterior and posterior columns. One or both columns may be damaged during traumatic spinal injury. Not all spinal injuries are unstable. Instability may be predicted by viewing anterior-posterior and lateral X-rays of the cervical spine. C1 and C2 injury necessitates special through-mouth views. Instability of the neck requires a different intubation technique. A safe intubation technique is described, the essence of which is to stabilise the neck with longitudinal traction and avoid extension at the fracture site.

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The response to a range of small doses of suxamethonium was evaluated in a patient with an atypical plasma cholinesterase who required a course of electroconvulsive therapy. A dose of 0.05-0.1 mg/kg of suxamethonium is suggested as a suitable test dose in patients suspected of having an atypical plasma cholinesterase.

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