A dosing nomogram for continuous infusion intravenous naloxone

Naloxone hydrochloride is extremely valuable for diagnosing and managing the opioid overdose. Due to naloxone's short half life and a long duration of action of most opioids, repeated naloxone dosing often is required to prevent the recurrence of respiratory depression. An alternative to repeated bolus administration is a continuous IV infusion. We conducted a two-phase study to determine the pharmacokinetics of naloxone and to develop a continuous dosing nomogram. In the first phase seven patients were given an IV bolus dose alone and serial plasma naloxone levels were determined. Naloxone elimination was found to be biexponential with the mean beta half life equal to 0.023 +/- 0.002 reciprocal minutes in two patients and 0.015 +/- 0.02 reciprocal minutes in five patients. In the second phase ten volunteers were given either a 2-mg or a 4-mg bolus dose followed by a 1.5-mg/hr or a 3-mg/hr continuous infusion. The mean volume of distribution of the central compartment was found to be 0.806 +/- 0.408 L/kg. The mean beta rate constant of elimination was found to be 0.036 +/- 0.027 reciprocal minutes. A computer simulation of the pharmacokinetic parameters determined in our study found that a continuous infusion of two-thirds of the bolus dose that resulted in reversal each hour will maintain the plasma naloxone levels equal to or greater than the naloxone levels that would have existed 30 minutes following the bolus dose.

Improved methods for venous access: the Port-A-Cath, a totally implanted catheter system

We prospectively evaluated the performance and rate of long-term complications with the Port-A-Cath (PAC), a totally implanted vascular access system. Two catheter styles were evaluated, a small-bore (SB) catheter (0.51-mm diameter) and a large-bore (LB) catheter (1.02-mm diameter), in conjunction with the use of a strict catheter care protocol. The PAC performed well, and with both SB and LB systems, no significant extravasation, skin necrosis, hematoma, septum damage or leakage, or subcutaneous portal infections occurred after 7,240 days of implantation and 1,435 days of use. Complications with the PAC system consisted of catheter occlusion (seven patients, 21.5%) and one instance of possible catheter infection (3.1%). Occlusions were limited to patients implanted with the SB catheter (seven of 16, 43.8%), and five of the seven (71.4%) occurred in patients receiving continuous infusion chemotherapy and/or total parenteral nutrition. Patency of the PAC system was maintained using a regular flushing schedule once every 30 days, a significant advantage compared with the daily maintenance schedule required with externally placed venous catheters. The results of this study suggest that the PAC system can provide a safe and reliable method for venous access in patients requiring intermittent or prolonged intravenous therapy.

Incidence of microbial colonization in open versus closed delivery systems for thermodilution injectate

The incidence of microbial colonization of injectate was studied in open and closed delivery systems used for thermodilution measurement of cardiac output. Patients with pulmonary artery catheters were prospectively randomized to receive either open two-bottle systems or closed systems. Paired cultures of injectate solution were withdrawn through the stopcock at the time of the initial set-up and every 12 h for 48 h. Injectate from eight (35%) of 23 patients with the open system and one (5%) of 20 patients with the closed system yielded a positive culture (p less than .05). Thirteen (10%) of 129 pairs of cultures were positive from the open system, compared to one (0.9%) of 111 pairs from the closed system (p less than .01). There was no statistically significant difference in the number of cardiac output injections between the two groups, but patients having more than the mean number of injections for cardiac output measurement had a significantly (p less than .05) greater likelihood of positive injectate cultures.

Coronary venous retroinfusion of procainamide: a new approach for the management of spontaneous and inducible sustained ventricular tachycardia during myocardial infarction

The efficacy of retrograde coronary venous delivery of procainamide for the management of spontaneous and inducible sustained ventricular tachycardia was evaluated and compared with systemic intravenous procainamide administration in 22 conscious dogs with permanent left anterior descending coronary artery occlusion. Selective retrograde injection of procainamide was achieved through an autoinflatable balloon catheter placed in the great cardiac vein, with the tip positioned in the vicinity of the site of left anterior descending coronary occlusion. Great cardiac vein retroinfusion of procainamide was significantly (p less than 0.05) more effective than systemic intravenous injection against spontaneous ventricular tachycardia 1 day after coronary artery occlusion (13 dogs) and against electrically induced sustained ventricular tachycardia in the 3 to 12 day postocclusion period (9 dogs). Significantly lower doses of procainamide were used with retroinfusion as compared with systemic administration, that is, 19.6 +/- 8.8 versus 35 +/- 0 mg/kg body weight during spontaneous tachycardia and 13.4 +/- 4.1 versus 32.1 +/- 2 mg/kg during induced tachycardia (p less than 0.01). Retroinfusion of saline solution through the great cardiac vein had no effect on either type of tachycardia. Myocardial tissue procainamide levels measured in infarcted and ischemic zones of the left anterior ventricular wall were 9 to 100 times higher after great cardiac vein retroinfusion than after systemic injection. Great cardiac vein dye injection studies demonstrated a preferential distribution in left ventricular regions supplied by the occluded coronary artery. It is concluded that regional coronary venous procainamide retroinfusion in dogs with myocardial infarction is more effective than systemic intravenous injection against both spontaneous and inducible sustained ventricular tachycardia. The greater efficacy of great cardiac vein treatment appears to be primarily related to selectively increased delivery of procainamide to ischemic myocardial sites.

Pediatric emergency intravenous access. Evaluation of a protocol

Effectiveness of a protocol for intravenous (IV) access during pediatric resuscitation was prospectively evaluated to determine whether utilization of a specified sequence of measures would reduce IV access time compared with resuscitations deviating from the protocol. The protocol involved rapid sequential attempts at percutaneous femoral vein catheterization, saphenous vein cutdown, and intraosseous infusions if initial percutaneous peripheral IV insertion failed. While no single technique provided completely reliable and rapid IV access, utilization of all techniques per protocol significantly improved IV access time. When initial percutaneous peripheral IV attempts failed, resuscitations in compliance with the protocol achieved IV access more rapidly (median, 4.5 minutes) than those deviating from the protocol (median, 10.0 minutes). Even with incomplete compliance, 66% of resuscitations achieved IV access within the first five minutes. Our experience indicates that IV access during pediatric resuscitation should rarely be delayed beyond the fifth minute if all available IV techniques are used.

Local treatment of renal allografts, a promising way to reduce the dosage of immunosuppressive drugs. Comparison of various ways of administering prednisolone

A method is described for continuous administration of immunosuppressive drugs directly into rat renal allografts. The drug is given via a catheter, introduced into the suprarenal or testicular artery of the transplanted kidney. The cannula is connected to an implantable osmotic minipump that delivers an immunosuppressive drug with continuous flow for 13 days. It is demonstrated that the technique as such has no detrimental or enhancing effects on renal allograft survival. Depending upon the pharmacokinetic properties of the drug administered, this technique allows a more or less selective treatment of renal allograft rejection. The method was used to test the effect of intrarenal administration of prednisolone on renal allograft survival. Intrarenal administration of this drug appeared to be superior to any other way of administration tested. A low dose of 4 mg/kg body weight per day given by continuous intrarenal infusion results in significant prolongation of graft survival, whereas continuous systemic administration of this dose is not effective. To induce prolongation of graft survival by i.p. administration the prednisolone dose had at least to be doubled. The results prove that during graft rejection local events within the graft are vulnerable to prednisolone. It is concluded that local treatment of allograft rejection is possible and that this approach represents a potentially important way to manipulate the immune response.

Emergency intraosseous infusions in children

Vascular access during advanced life support is essential. Vascular access in the critically ill child can be particularly difficult and often causes unacceptable delay. Intraosseous infusion provides safe, rapid, reliable access to the venous circulation. A case is presented illustrating the value of familiarity with this procedure. Use of the bone marrow for emergency administration of fluids and medications should be considered early in resuscitation until vascular access is obtained.

Pediatric resuscitation without an intravenous line

The case of a 3-month-old male infant who was found unresponsive and cyanotic in a crib at home is presented. On arrival in the emergency department the child was receiving basic cardiopulmonary resuscitation (CPR) by a rescue squad and was without vital signs in asystole. The patient achieved a stable rhythm and blood pressure before intravenous access was obtained. Epinephrine and atropine were given via the endotracheal route and sodium bicarbonate through intraosseous infusion.

Differences in drug delivery with peripheral and central venous injections: normal perfusion

The differences between central venous (CV) and peripheral venous (PV) injections with respect to drug delivery times and peak concentrations in the left ventricle are examined. In this drug-delivery model, anesthetized dogs (n = 7) received both PV and CV injections of a radionuclide tracer. Measurements of radioactivity levels were made over each ventricle during normal perfusion. There was no statistically significant difference in left ventricular delivery times or peak radioactivity levels between the two different routes. When delivery time was corrected for variations in flow rate, a small but statistically significant difference was seen, the CV route being faster than the PV route (P less than 0.05). The magnitude of the observed difference for normal perfusion (2 seconds) is unlikely to be of clinical significance.

Totally implantable catheters for cancer chemotherapy: French experience on 325 cases

325 implantable catheters (PAC) were successfully used for treatment of 310 patients with neoplastic diseases in 21 French medical centers. 263 were placed in central venous sites; 43 in the hepatic artery and 11 in intra-portal sites. There was no failure at insertion time nor was there any death attributable to the method. While average duration of catheterization was 182 days, 72 catheters remain patent after one year of use or longer. Occlusion risk was found to be 3.6%: 1.5% for IV sites and 13.9% for intra-arterial sites (due to smaller inner diameter). 2.4% of the implantations showed cutaneous necrosis and in 2.7% sepsis occurred. Sepsis was much more likely to occur after percutaneous insertions. These results support the use of this device for long term chemotherapy.

Controlled studies of a new microprocessor-based portable infusion pump

A new microprocessor-controlled portable infusion pump, the Pancretec Provider IV 2000 TM was tested in vitro and in vivo in cancer patients. The Provider is a rotary peristaltic, battery-powered pump capable of flow rates of 0.2 to 83 ml/hour with delivery volumes up to 1999 ml. Two programming modes are available: intermittent infusion and continuous infusion. Bench tests showed the flow rate accuracy to be within 96% of the desired rate. Flow rate precision was similarly excellent at +/- 2%. Clinical studies were performed in 14 ambulatory patients receiving continuous infusion antineoplastic or analgesic drugs over 5-60 days as outpatients. The majority of infusions delivered fluoropyrimidines via indwelling central venous access ports. Two of the patients received long term (60 days) continuous infusion of analgesics for pain control. Flow rate accuracy with the pumps was within +/- 5% in 90% of the 27 infusion courses (244 patient-days of continuous infusion therapy). A significant therapy deviation (interruption 10% of the desired course) occurred in three instances. One related to a procedural error (incomplete cartridge insertion into the pump), two were caused by fluid leakage which interrupted pump function. Defect alarms (both visual and audible) operated in both instances. A KVO flow rate of 0.1 ml/hr was also found to be adequate to maintain catheter patency in peripheral veins over a 24-hour period in two normal volunteers. We conclude that the Provider pump is an accurate, reliable and state of the art infusion system with wide clinical applicability.