Norig Ellison

Ultrasound-guided cannulation of the internal jugular vein. A prospective randomized study

This study compares the ease, safety, and success rate of internal jugular vein cannulation using a standard approach based on anatomic landmarks alone with an ultrasound-guided approach

Intraoperative management of patients with heparin-induced thrombocytopenia.

For 11 patients with confirmed heparin-induced thrombocytopenia, we used reversible platelet inhibition with iloprost, a stable prostacyclin analogue, to permit safe heparin administration for cardiac (n = 9) or vascular (n = 2) operations. In vitro, iloprost (0.01 mumol/L) prevented both heparin-induced platelet aggregation and 14C-serotonin release in all patients. Therefore, intraoperatively, a continuous infusion of iloprost was started before administration of heparin and was continued until 15 minutes after administration of protamine. For cardiac patients, after heparin administration, the whole blood platelet count did not change (171,000 +/- 29,000/microL versus 174,000 +/- 29,000/microL, mean +/- standard error of the mean); no spontaneous platelet aggregation was observed, and plasma levels of the alpha-granule constituents platelet factor 4 and beta-thromboglobulin increased from 38 +/- 14 and 140 +/- 18 ng/mL to 591 +/- 135 and 235 +/- 48 ng/mL, respectively. Fibrinopeptide A levels actually decreased from 287 +/- 150 to 27 +/- 6 ng/mL. Furthermore, adenosine diphosphate-induced platelet activation was preserved, postoperative bleeding times were unchanged, and no heparin-related deaths occurred. Similar results were obtained in both vascular patients. We conclude that temporary platelet inhibition with iloprost now permits safe heparin administration in all patients with heparin-induced thrombocytopenia who require a cardiac or vascular operation.

Platelet aggregation following heparin and protamine administration.

The effects of heparin, protamine, and the heparin-protamine complex on the abilities of platelets to aggregate in vitro in response to adenosine diphosphate (ADP) and epinephrine were determined. Citrated blood was obtained from normal volunteers and portions were treated with heparin, protamine, and three different ratios of heparin and protamine. The threshold concentrations of ADP and epinephrine required to produce complete platelet aggregation were then determined. Compared with control citrated plasma, the geometric mean of the threshold concentration for ADP in the heparinized sample was decreased twofold, from 1.88 to 0.94 micrometer; and that for epinephrine more than threefold, from 0.5 to 0.14 micrometer. In contrast, the threshold concentration for ADP was increased to 3.68 micrometer in the neutralized and to 2.78 micrometer in the overneutralized samples and that for epinephrine to 1.62 micrometer in the neutralized and 1.82 micrometer in the overneutralized samples. These data indicate that heparin increases the sensitivity of platelets to ADP and epinephrine as determined by platelet aggregation, and protamine added to heparinized blood not only reverses this effect, but decreases platelet sensitivity when it is added in concentration that neutralize heparin. Additional protamine has no further effect, and protamine alone has no effect on platelet aggregation.

Monitoring Heparin Anticoagulation and Its Neutralization

Heparin anticoagulation and its neutralization were monitored by three different techniques: a manual protamine titration, an automated activated coagulation time, and an automated protamine titration. All three techniques provided satisfactory information. The decision of which to use must be based on other considerations such as available manpower and cost of equipment. The effect of using the automated protamine titration test on heparin and protamine requirements, and on blood loss measured intraoperatively after bypass and in overnight chest bottle drainage in two groups of comparable patients undergoing coronary artery bypass operation was studied. The heparin requirements were similar (24,420 +/- 584 units, control group; 23,550 +/- 849 units, treatment group), but the protamine requirements were markedly different (429 +/- 14.7 mg, control; 258 +/- 10.4 mg, treatment; p < 0.05). There was no statistical difference in intraoperative blood loss or overnight chest bottle drainage.

Risk factors for clinically important adverse events after protamine administration following cardiopulmonary bypass

OBJECTIVES The purpose of this study was to determine risk factors for adverse events following protamine administration after cardiopulmonary bypass. BACKGROUND Intravenous protamine administration is associated with a risk of severe systemic reactions. However, risk factors for these events have not been well delineated, thus hampering development of preventive strategies. METHODS A case-control study nested within a cohort of consecutive patients undergoing surgery requiring cardiopulmonary bypass was performed. The primary case definition included those events (pulmonary hypertensive and systemic hypotensive) occurring within 10 min of protamine administration in the absence of other measurable causes of hemodynamic compromise. RESULTS Comparing the 53 cases to the 223 control subjects, three risk factors were independently associated with events (multivariable odds ratio [95% confidence interval]): neutral protamine Hagedorn insulin use (8.18 [2.08, 32.2]); fish allergy (24.5 [1.24, 482.3]), and a history of nonprotamine medication allergy (2.97 [1.25, 7.07]). These risk factors demonstrated an increasingly strong association with progressively more specific case definitions. An estimated 39% of cardiopulmonary bypass patients had one or more of these risk factors. Prior intravenous protamine, central venous pressure prior to protamine, preoperative ejection fraction and the need for inotropes when coming off bypass did not exhibit statistically significant associations with events (all p > 0.15). Prior protamine allergy was associated specifically with an increased risk of pulmonary hypertension (multivariable odds ratio 189; 95% confidence interval 13, 2,856). CONCLUSIONS Immunologic factors are important in predisposing individuals to protamine reactions, and a substantial proportion of patients are at considerably increased risk Strategies to reduce the risk of protamine-associated events are needed.

Mortality and adverse events after protamine administration in patients undergoing cardiopulmonary bypass.

UNLABELLED We designed this study to determine whether adverse hemodynamic events after a protamine administration increase the risk of in-hospital mortality. Using a retrospective cohort study design, medical and anesthesia records of patients undergoing cardiopulmonary bypass (CPB) at the Hospital of the University of Pennsylvania, Philadelphia, between 1990 and 1994 were reviewed. Adverse events after a protamine administration were determined using strict, predefined criteria, and in-hospital mortality was assessed without knowledge of exposure status. Mortality was more frequent among the 53 patients with adverse events (13.2%) than the 223 patients without events (2.7%; crude odds ratio 5.50; 95% confidence interval, 1.49-20.6). After adjusting for confounders, the odds ratio was 6.98 (95% confidence interval, 1.36-35.9; P = 0.017). Those suffering severe events had the highest mortality (23.5% compared with 8.3% among those with less severe events versus 2.7% among those without any event, P = 0.001 for trend). In addition, the odds ratio was largest when using the strictest definition for protamine-related events. In conclusion, patients undergoing CPB who experience adverse events after a protamine administration have an increased risk of in-hospital mortality. Further studies to confirm these findings and development and testing of protamine alternatives or prophylactic therapies are required to determine if mortality can be reduced. IMPLICATIONS A retrospective cohort study demonstrated an association between adverse events after a protamine administration and increased in-hospital mortality.

Guide wires--a caution.

Popularity of the Seldinger technique of vascular cannulation has resulted in widespread use of spring guide wires. Though employed to make vascular cannulation easier and safer, guide wires are not without potential hazard. The review of guide wire design presented gives the operator an awareness of the potential problems inherent in their use. Three observed complications are described and suggestions are given for enhancement of utility and safety.

Carotid endarterectomy in patients with heparin-induced platelet activation: comparative efficacy of aspirin and iloprost (ZK36374)

Patients with heparin-induced platelet activation who are reexposed to heparin may have recurrent thrombocytopenia, intravascular thrombosis, arterial emboli, or sudden death. To permit carotid endarterectomy in two patients with confirmed heparin-induced platelet activation, we compared the efficacies of aspirin and iloprost, a stable analogue of prostacyclin, in preventing heparin-induced platelet activation. In the first patient, although aspirin prevented both in vitro heparin-induced platelet aggregation (70% without and 7.5% with aspirin) and 14C serotonin release (48% without and 0% with aspirin), intraoperative administration of heparin resulted in an increase in plasma levels of platelet factor 4 from 8 to 260 ng/ml and beta-thromboglobulin levels from 29 to 39 ng/ml. In addition, the circulating platelet count decreased from 221,000 to 174,000 microliters, and 15% spontaneous platelet aggregation was observed. Fortunately, fibrinopeptide A levels remained less than 10 ng/ml intraoperatively, and no thrombotic complications occurred. In the second patient, aspirin did not prevent heparin-induced platelet aggregation in vitro (65% without and 41% with aspirin); however, iloprost (0.01 mumol/L) prevented both in vitro heparin-induced platelet aggregation (59.5% without and 0.0% with iloprost) and 14C serotonin release (56.7% without and 0.0% with iloprost). Therefore, a continuous infusion of iloprost was begun before administration of heparin and was continued until 20 minutes after reversal of heparin with protamine. After intraoperative administration of heparin, plasma levels of platelet factor 4 increased from 19 to 200 ng/ml, and beta-thromboglobulin levels increased from 56 to 76 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Problems in Geriatric Anesthesia

Meticulous clinical judgment, intraoperative deliberate speed, and technical skill, combined with dedicated postoperative care, will enable many geriatric patients to live longer, more healthy lives. In view of the increasing numbers of geriatric patients appearing on operating room lists, their unique features must be appreciated by all concerned in order to insure optimal care.

Bradykinin, Plasma Protein Fraction, and Hypotension

A directive from the Food and Drug Administration indicates that the use of plasma protein fraction (PPF) is contraindicated during cardiopulmonary bypass because of possible hypotension. Bradykinin has been implicated as the cause of this hypotension. Bradykinin levels were measured by radioimmunoassay in PPF and in 5% albumin and were found to be consistently elevated in the former and occasionally in the latter. The addition of PPF to pump primes resulted in significantly elevated levels of bradykinin, which rapidly cleared, indicating that extrapulmonary sites of bradykinin inactivation were efficient. The potential hypotensive effect of PPF was observed by determining the change in mean perfusion pressure in two groups of patients: one group with a 3,000 ml crystalloid prime and the other with a prime of 2,000 ml of crystalloid and 1,000 ml of PPF. There was no significant difference in the perfusion pressure between the two groups at any point, and the hypotensive effects seen in both groups were readily treated, suggesting that the directive against the use of PPF during cardiopulmonary bypass may be unnecessarily restrictive.