Different heparin lots: Does it matter?

OBJECTIVE

To assess the impact of heparin lot on the correlation between heparin concentration and activated partial thromboplastin time (aPTT), the aPTT therapeutic range, and the heparin level.

DESIGN

Retrospective analysis of data from 2 previous studies.

SETTING

Teaching institution with 929 beds.

PATIENTS

Ninety-five patients receiving heparin with 5 different lots (study 1) and 35 patients receiving heparin with 3 different lots (study 2).

MAIN OUTCOME MEASURES

Laboratory-based aPTT and heparin level by anti-factor Xa analysis. Standard heparin curves were created for each lot. Each patient's heparin level was determined off each standard curve.

RESULTS

Correlations between heparin concentration and aPTT ranged from 0.87 to 0.89 (study 1) and 0.86 to 0.87 (study 2). Slopes of regression lines were not significantly different. Therapeutic ranges generated from lot-specific heparin levels were similar. Average bias in heparin levels from varying lots ranged from 0.005 to 0.036 units/mL.

CONCLUSIONS

The recommendation to reevaluate the aPTT therapeutic range with each new lot of heparin requires further evaluation.

Use of the activated partial thromboplastin time for heparin monitoring

The objectives of the present study were to evaluate the relationship between heparin concentration and activated partial thromboplastin time (aPTT) results, define a heparin concentration-derived therapeutic range for each aPTT instrument, compare aPTT- and heparin concentration-guided dosage adjustment decisions, and compare laboratory- and bedside aPTT-guided decisions. In phase 1, 102 blood samples were analyzed for bedside and laboratory aPTTs and heparin concentration (used to establish aPTT therapeutic range). In phase 2, 100 samples were analyzed in the same manner. Correlations for aPTT compared with heparin ranged from 0.36 to 0.82. Dosage adjustment decisions guided by the aPTT agreed with those based on heparin concentration 63% to 80% of the time. Laboratory and bedside aPTT dosage adjustment decisions agreed 59% to 68% of the time. The correlation of aPTT with heparin concentration and agreement between aPTT- and heparin-guided decisions vary with the aPTT instrument. Decisions guided by laboratory aPTT results often disagree with decisions guided by bedside aPTT results.

Anaphylactoid reaction to levofloxacin

Anaphylactoid and/or anaphylactic reactions to fluoroquinolones are estimated to occur in 0.46-1.2/100,000 patients. A 49-year-old woman with a history of asthma was admitted for a presumed asthma exacerbation related to an infectious process. She was given levofloxacin and standard management for an acute exacerbation. On two occasions the patient's respiratory distress worsened, requiring intubation. The second reaction occurred immediately after levofloxacin administration and was accompanied by a marked cutaneous reaction. Levofloxacin was discontinued, and supportive care was provided. No further symptoms occurred. The patient later was found to have been started on levofloxacin before admission for a suspected upper respiratory infection.

The use of calcium salts in the prevention and management of verapamil-induced hypotension

OBJECTIVE

To review the available literature on the use of intravenous calcium salts for the prevention of hypotension associated with intravenous verapamil.

METHODS

A MEDLINE search (1966-June 1999) identified pertinent articles; references from these articles were identified to serve as additional resources.

DISCUSSION

Verapamil is effective in inhibiting atrioventricular nodal conduction, thereby controlling ventricular rate in patients with atrial fibrillation/flutter and terminating paroxysmal supraventricular tachycardia. However, hypotension may be caused by the negative inotropic and vasodilating effects of verapamil. In vitro and animal data suggest that calcium pretreatment may minimize the effects of verapamil on cardiac output and blood pressure. Case reports suggest that intravenous calcium may be useful for both prevention and reversal of the hemodynamic effects of verapamil. A number of small clinical trials have been performed, suggesting that calcium administered prior to intravenous verapamil results in a decreased incidence of hypotension. The most common adverse effect of intravenous calcium is flushing.

CONCLUSIONS

Calcium pretreatment prior to intravenous calcium-channel blocker administration should be considered in patients in whom further reductions in blood pressure may precipitate hypoperfusion or worsen underlying cardiovascular status. A dose of calcium gluconate 1 g (ionized calcium 90 mg) administered over three minutes is recommended for preventing or lessening the hypotensive effect of verapamil without affecting the antiarrhythmic effects of verapamil.

Correlation of activated clotting time and activated partial thromboplastin time to plasma heparin concentration

STUDY OBJECTIVE

To determine the correlation between activated clotting time (ACT) or activated partial thromboplastin time (aPTT) and plasma heparin concentration.

DESIGN

Two-phase prospective study.

SETTING

University-affiliated community hospital.

PATIENTS

Thirty patients receiving continuous-infusion intravenous heparin.

INTERVENTIONS

Measurement of ACT, aPTT and plasma heparin concentrations.

MEASUREMENTS AND MAIN RESULTS

Linear and log linear correlations were determined between clotting time tests and heparin concentrations. Linear correlations yielded r values of 0.58 for ACT (p=0.008) and 0.89 for aPTT (p=0.0001). Log linear correlations yielded r values of 0.60 for ACT (p=0.005) and 0.88 for aPTT (p=0.0001). A decision analysis was performed to determine possible consequences of dosage adjustments based on either test in relationship to the decision based on plasma heparin concentration. The decision analysis based on ACT disagreed with corresponding decisions based on plasma heparin concentration in 15 of 30 patients; 13 disagreements may have increased the risk of bleeding, and the other 2 may have increased the risk of thrombosis. Decisions based on aPTT disagreed with corresponding decisions based on plasma heparin concentration in 13 of 30 patients; 2 disagreements may have increased the risk of bleeding, and the other 11 may have increased the risk of thrombosis.

CONCLUSION

There are significant statistical linear and log linear correlations between both clotting time tests and plasma heparin concentrations, with aPTT showing stronger correlation than ACT. However, decisions regarding heparin therapy based on ACT may increase a patient's risk of bleeding, whereas decisions based on aPTT may increase the risk of thrombus progression or rethrombosis.

Pharmaceutical care in medical progressive care patients

OBJECTIVE

To develop, implement, and assess the outcomes of a system for providing pharmaceutical care to medical progressive care patients.

METHODS

A system for providing pharmaceutical care was developed and implemented for an 8-week period beginning in June 1995. Both patient care outcomes and drug therapy cost change from the intervention period were compared with those of an 8-week baseline period. Variables compared included unit length of stay, hospital length of stay, transfers to the intensive care unit, readmissions, and adverse drug reactions requiring treatment. Differences between periods for these variables were assessed by using chi 2 tests and t-tests with alpha set at p less than 0.05. The clinical significance of the interventions were assessed independently by four physicians: two intensivists and two internists. The total drug therapy cost change from the intervention period was calculated as follows: total cost avoidance from individual recommendations subtracted from the total cost incurred from individual recommendations.

RESULTS

The pharmacist evaluated 152 patients during the intervention period. A total of 235 pharmacotherapy recommendations were made on 103 patients, of whom 86.4% were accepted. Significantly fewer adverse drug reactions (ADRs) received treatment during the intervention period (p = 0.027). The mean unit length of stay was lower during the intervention period (4.8 +/- 3.7 d) than during the baseline period (6.0 +/- 5.6 d); however, this difference was not significant (p = 0.053). Individual physician assessment of the pharmacists' recommendations revealed that 75.8% were considered somewhat significant, significant, or very significant. The total drug therapy cost change from the intervention period was -$6534.53. The projected annual drug therapy cost reduction from this study is $42,474.45.

CONCLUSIONS

The provision of pharmaceutical care to medical progressive care patients was associated with a substantial decrease in drug therapy cost and a decrease in the number of ADRs that required treatment.

Association of SIADH with selective serotonin reuptake inhibitors

While SSRIs have been reported to cause SIADH, the actual incidence remains unclear. From the published case reports, the elderly may appear to be at higher risk of developing SIADH. Symptomatic and laboratory presentation in these patients includes lethargy, hyponatremia, elevated urinary sodium excretion, and hyperosmolar urine. However, evaluation of SSRI-induced SIADH has been incomplete. Normalization of serum sodium concentrations occurred after discontinuation of the SSRI and/or fluid restriction. Of the published reports, only three convincingly demonstrated a causative role of SSRI-induced SIADH by rechallenge. As a result, the published case reports cannot definitely established a causal relationship. Pharmacists can play an important role in the care of patients with suspected SSRI-induced SIADH. Pharmacists should be familiar with the clinical and biochemical presentation of SIADH as well as the limitations of published case reports implicating SSRIs as a cause of SIADH. A complete medication history, including when these agents were initiated or discontinued, should be taken. Pharmacists must understand, recognize, and ensure the proper monitoring parameters, namely daily fluid intake, patient weight, and serum sodium concentrations.

Patient-controlled analgesia versus patient-controlled analgesia plus continuous infusion after hip replacement surgery

OBJECTIVE

To compare the efficacy and adverse effect profile of patient-controlled analgesia (PCA) versus PCA plus continuous infusion (PCACI) after hip replacement surgery.

DESIGN

Prospective, randomized, open pilot study.

SETTING

Large teaching institution.

PARTICIPANTS

Thirty-four patients undergoing hip replacement or revision of hip replacement surgery.

INTERVENTIONS

Patients were randomized to receive PCA morphine: 1 mg with 6-minute lockout, or PCACI, using the same dose, with a 0.5-1 mg/h continuous infusion. Pain intensity, sedation, narcotic use, injection/attempt ratio (I/A), and adverse effects were assessed.

RESULTS

No significant differences in pain intensity were identified. Morphine use was not different between groups: PCA 61.8 +/- 35.0 and PCACI 74.2 +/- 54.9 mg (p =0.394). A trend toward an increased 12-hour I/A ratio was evident in the PCACI group: PCA 0.73 +/- 0.18 and PCACI 0.86 +/- 0.17 (p =0.073). Patient-reported adverse effects, sedation, and inability to sleep secondary to pain occurred similarly. Eight of 18 PCACI patients required discontinuation of either the continuous infusion mode or of PCA therapy entirely secondary to adverse effects.

CONCLUSIONS

When compared with PCA therapy, PCACI was not associated with improved pain control and more patients receiving PCACI required discontinuation of therapy secondary to adverse effects.

Changing perspectives of stress gastritis prophylaxis

OBJECTIVE

To present recent advances in stress gastritis prophylaxis in the critically ill and review considerations in selection of a prophylactic agent.

DATA SOURCES

Information was obtained from MEDLINE search, reference lists from articles identified in search, and from review articles.

STUDY SELECTION

Emphasis was placed on controlled trials conducted within the last 5 years.

DATA EXTRACTION

All literature was assessed for methodology, results, and conclusions. Results of prospective, randomized trials, and meta-analyses are summarized.

DATA SYNTHESIS

Histamine2-receptor antagonists, antacids, and sucralfate appear equally effective in preventing stress gastritis in the critically ill. A definitive cause-effect relationship between histamine2-receptor antagonists and increased incidence of nosocomial pneumonia has not yet been established. The indications for using a prophylactic agent and consideration in selecting an agent should include an evaluation of the following: risk factors for gastritis including the type of intensive care patient, comparative efficacy, adverse effects, drug interactions, cost, and ease of administration. The least expensive, safest agent requiring minimal monitoring is sucralfate. Prevention of stress gastritis has never been shown to reduce morbidity or mortality significantly.

CONCLUSIONS

Controversies still exist regarding the need to provide prophylaxis, the choice of an agent, and the relative importance of previously identified risk factors. Further well-designed studies are needed before consensus can be reached.

An exploratory analysis of medication utilization in a medical intensive care unit

OBJECTIVES

To evaluate patterns of medication use in a medical intensive care unit (ICU) and to explore relationships between drug use, patient age, admitting diagnosis, Acute Physiology and Chronic Health Evaluation (APACHE II) scores, length of stay, and survival.

DESIGN

Combination prospective and retrospective study.

SETTING

Medical ICU in a large teaching institution.

PATIENTS

Patient admissions (n = 191) to a medical ICU during a 4-month study period.

INTERVENTIONS

The following data were collected: age, length of stay, diagnosis, physiologic variables necessary for APACHE II scores, medications administered, and survival.

MEASUREMENTS AND MAIN RESULTS

The mean length of stay of the study patients was 5.2 +/- 9.8 days. Overall mortality rate was 33%. The mean age of survivors, 62.7 yrs, was significantly (p < .05) lower than that value for nonsurvivors (68.6 yrs). Postcardiopulmonary resuscitation (CPR) or -stroke patients had a mortality rate that was higher than the overall mortality rate (p < .05). APACHE II scores of > 19 were associated with a reduced survival rate when compared with the overall mortality rate. The mean daily and mean total number of medications administered per patient were 7.5 +/- 3.4 and 12.1 +/- 7.6, respectively. Antihypertensives/vasodilators and gastrointestinal prophylaxis medications were administered most commonly in 69% and 65% of patients, respectively. The median total drug use per patient was significantly greater in nonsurvivors vs. survivors (13 and 10, respectively, p < .02). There was a positive linear relationship between total medication use and log length of stay (r2 = .62). Patients admitted post-CPR or with seizures received the highest number of medications (p < .05).

CONCLUSIONS

Patients admitted to the medical ICU receive multiple medications from a variety of pharmacologic classes. Prolonged length of stay, certain admitting diagnoses, and death are associated with increased medication administration. Age, certain admitting diagnoses, and APACHE II scores are significantly related to survival.

Retrospective evaluation of patient-controlled analgesia use in a large teaching institution

Because of a significant increase in the number of patients receiving patient-controlled analgesia (PCA) therapy at our institution, we conducted a review of PCA use. Our objectives were to determine if a PCA recording document (monitoring form) could be used to identify potential problems associated with PCA therapy and to identify measures that could be taken to improve analgesic therapy with this method of administration. The PCA recording document for each patient was reviewed retrospectively to identify patients suspected of having problems with the therapy. Three criteria addressing duration of therapy, change in prescribed narcotic, and respiratory rate were used to evaluate PCA therapy. The standard was set at 100 percent. Complete patient records were reviewed for those patients not meeting the standard to determine whether problems actually existed. PCA recording documents were reviewed for 518 patients. Sixty-one patients did not meet the standard. Of these 61 patients, 41 (67.2 percent) were found to have problems with PCA therapy. Suspected adverse reactions occurred in 27 of these 41 patients and 14 experienced inadequate pain control. Nausea and vomiting were the most prevalent adverse reactions. Our results indicate that PCA therapy is discontinued in many patients because of inadequate pain relief and suspected narcotic-induced nausea and vomiting. To improve analgesic therapy, clinicians should be reeducated regarding ways to optimize analgesic therapy, and a prospective PCA monitoring service should be considered.

Meperidine serum concentrations and analgesic response in postsurgical patients

We examined the relationship between serum concentrations of meperidine hydrochloride and analgesic response in postsurgical patients allowed to use patient-controlled analgesia (PCA) and compared these findings with those of patients receiving conventional intramuscular (IM) dosing. Six patients who had undergone abdominal surgery were randomly assigned to receive postoperative analgesia with either PCA or IM therapy. A sequence of five-point pain and sedation scores and serum meperidine concentrations were obtained in all patients the day after surgery. Minimum effective concentration (MEC) was defined as that concentration of meperidine at which patients felt pain relief as indicated by a decrease in pain rankings. The mean MEC for patients using PCA, 296 +/- 112 ng/mL, was significantly lower than the mean MEC in patients receiving IM dosing (551 +/- 164 ng/mL, p less than 0.05). The mean maximum change in meperidine concentrations in the PCA group, 177 +/- 88 ng/mL, was significantly lower than that of the IM group (484 +/- 125 ng/mL, p less than 0.05). Mean maximum changes in pain and sedation scores for patients in the PCA group were not significantly different from those of the IM group. During this investigation patients using PCA experienced smaller swings in meperidine concentrations than did patients receiving IM injections. MEC analysis suggests that PCA patients may experience pain relief at lower meperidine concentrations than those needed by IM patients.

Ofloxacin: a review

Ofloxacin is a new fluorinated quinolone antibiotic with a broad spectrum of activity against a variety of gram-positive and -negative bacteria including Enterobacteriaceae, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus. In addition, ofloxacin has significant activity against Neisseria gonorrhoeae, Chlamydia trachomatis, and Mycobacterium tuberculosis and this may give rise to new indications for the class of quinolone antibiotics. Clinical trials to date have demonstrated the efficacy of ofloxacin in the treatment of lower respiratory tract infections, urinary tract infections, and sexually transmitted diseases. Adverse effects to ofloxacin are usually mild and include gastrointestinal, central nervous system, and hypersensitivity reactions. Significant drug interactions with ofloxacin have not been reported.

Phenytoin hepatotoxicity: a review of the literature

Phenytoin hepatotoxicity is a serious idiosyncratic reaction that occurs in less than one percent of patients. The onset of symptoms occurs early in therapy, usually within the first six weeks. Presenting symptoms often include fever, rash, lymphadenopathy, hepatomegaly, anorexia, and myalgias or arthralgias. Other significant findings that may develop throughout hospitalization are jaundice, periorbital or facial edema, and splenomegaly. The following alterations in liver function tests are associated with phenytoin hepatotoxicity: elevations in serum aminotransferases, lactic dehydrogenase, alkaline phosphatase, bilirubin, and prothrombin time. Rechallenges, lymphocyte stimulation test, and liver biopsy have been used to aid in the diagnosis. Rechallenge is the most definitive diagnostic approach; however, its use is limited by the potential of a fatal reaction. Although the exact mechanism of phenytoin hepatotoxicity is unknown, the majority of literature supports a hypersensitivity mechanism. The severity of this adverse effect ranges from self-limiting to fatal. Since 1965 six fatal cases have been reported. To date, sufficient evidence is not available to establish treatment guidelines. Discontinuation of phenytoin therapy is warranted.