Seiji Hida

The Influence of Nicardipine-, Nitroglycerin-, and Prostaglandin E 1 -Induced Hypotension on Cerebral Pressure Autoregulation in Adult Patients During Propofol-Fentanyl Anesthesia

UNLABELLED We investigated the influence of drug-induced hypotension at a mean arterial pressure (MAP) of 60-70 mm Hg on cerebral pressure autoregulation in 45 adult patients during propofol-fentanyl anesthesia. Time-averaged mean blood flow velocity in the right middle cerebral artery (Vmca) was continuously measured at a PaCO(2) of 39-40 mm Hg by using transcranial Doppler ultrasonography. Hypotension was induced and maintained with a continuous infusion of nicardipine, nitroglycerin, or prostaglandin E(1). Cerebral autoregulation was tested by a slow continuous infusion of phenylephrine to induce an increase in MAP of 20-30 mm Hg. From the simultaneously recorded data of Vmca and MAP, cerebral vascular resistance (CVR) was calculated as MAP/Vmca. Furthermore, the index of autoregulation (IOR) was calculated as DeltaCVR/DeltaMAP, where DeltaCVR = change in CVR and DeltaMAP = change in MAP. The test was performed twice for each condition on each patient: baseline and hypotension. The IOR during baseline was similar among the groups. During nitroglycerin- and prostaglandin E(1)-induced hypotension, IOR was not different from baseline. In contrast, during nicardipine-induced hypotension, IOR significantly decreased compared with baseline (0.37 +/- 0.08 versus 0.83 +/- 0.07, P < 0.01). In conclusion, nicardipine, but not nitroglycerin or prostaglandin E(1), significantly attenuates cerebral pressure autoregulation during propofol-fentanyl anesthesia. IMPLICATIONS Vasodilators may influence cerebral autoregulation by changing cerebral vascular tone. Nicardipine, but not nitroglycerin or prostaglandin E(1), attenuated cerebral pressure autoregulation in normal adult patients during propofol-fentanyl anesthesia.

Knotting of two central venous catheters: a rare complication of pulmonary artery catheterization.

To the Editor: A unique complication of pulmonary artery (PA) catheter use is knotting. We describe a case of a knot between a central venous catheter and a PA catheter, and the successful nonsurgical unknotting and removal of the catheter. A 31-year-old pregnant woman in cardiogenic shock resulting from a tachycardia-induced cardiomyopathy was transferred to the intensive care unit. On admission, a triple-lumen central venous catheter was introduced via the right internal jugular vein. Despite sufficient hydration and continuous infusion of inotropic agents, her blood pressure was unstable. Circulatory supports by intraaortic balloon pump (IABP) and percutaneous cardiopulmonary support system (PCPS) were introduced for severe heart failure (ejection fraction was 10%). On the 6th ICU day, a PA catheter was inserted through the left internal jugular vein to monitor hemodynamic status during weaning from PCPS. The catheter was inserted without difficulty and advanced easily, and the correct position was confirmed on the chest X-ray. Weaning from the PCPS was completed on the 6th ICU day, and the IABP was removed on the 7th ICU day because her hemodynamic status became relatively stable. However, as she still had multiple organ failure, we retained the PA catheter. Although a chest X-ray showed normal configuration of the catheters on the morning of the 11th ICU day, monitoring failure of pulmonary arterial pressure happened abruptly about 9 p.m. without any catheter manipulations. We attempted to remove the PA catheter in the usual manner. However, resistance was felt during withdrawal of the catheter, and repeated traction was unsuccessful. Then, we confirmed a loose knot between the central venous catheter and the PA catheter in the superior vena cava on the chest X-ray (Fig. 1). As the knotting was relatively loose, we pushed the PA catheter forward to unknot the catheters, and then the catheter was successfully removed. The case of knotting of two catheters is rare [1–3]. Cases of knotted catheters functioning normally for several days have not been previously reported. We suspected that the catheter knotted when sudden malfunction of the catheter was found; in fact, the catheter was in normal configuration in the morning. The cause of knotting was not clear, and the catheter was not manipulated before discovery of the knotting. Several technical methods for removal of the knotting have been developed in cases that are more difficult to handle. One approach is to tighten the knot as much as possible so that it may be removed through the vein insertion site. Alternative approaches are to use a retrieval basket, a loop snare formed by a double-over guide wire or loop snares, endomyocardial biopsy forceps, or an inflated angiography balloon to expand the diameter of the knot [4]. Open surgical removal of knotted catheters is reserved for large, multiple loop knots or knots that are fixed within the cardiac chamber. In summary, we experienced a case of a spontaneous knotting between a central venous catheter and a PA catheter several days after placement. A catheter knotting should be considered when malfunction of the catheter is encountered. Withdrawal of a PA catheter should be performed cautiously, and a chest X-ray should be taken S. Hida (&) S. Ohashi H. Kinoshita T. Honda S. Yamamoto J. Kazama H. Endoh Department of Emergency and Critical Care Medicine, Niigata University Faculty of Medicine, 1-757 Asahimachi, Niigata 951-8510, Japan e-mail: ukhida@med.niigata-u.ac.jp