Nephrotoxicity of contrast media following cardiac angiography: pathogenesis, clinical course, and preventive measures, including the role of low-osmolality contrast media

Anticoagulation: Low-Molecular-Weight Heparins in Renal Impairment and Obesity: Available Evidence and Clinical Practice Recommendations Across Medical and Surgical Settings

Objective

To develop practical recommendations for the use of low-molecular-weight heparins (LMWHs) as prophylaxis and treatment of venous thromboembolism and acute coronary syndromes in patients with impaired renal function or obesity.

Data Sources

Multiple MEDLINE searches were performed (November 2008) to identify studies for inclusion, using a comprehensive list of search terms including, but not limited to, LMWH, enoxaparin, dalteparin, tinzaparin, obesity, weight, renal, kidney, elderly, monitoring, and anti-Xa.

Study Selection And Data Extraction

Only articles published in English that were relevant for this review were included.

Data Synthesis

In the majority of patients, standardized prophylaxis or treatment doses of LMWHs can be used without the need for monitoring and adjusting regimens. For patients with severe renal impairment (estimated creatinine clearance [CrCl] <30 mL/min), doses of some LMWHs should be adjusted or unfractionated heparin should be used instead. CrCl should be estimated using the Cockcroft-Gault method. Differences are noted in the degree of accumulation of various LMWHs in patients with moderate-to-severe renal impairment, and thus, the degree of dose adjustment may differ among the various LMWHs. Increasing the prophylactic doses of LMWH may be appropriate in morbidly obese patients (body mass index ≥40 kg/m2). The use of total body weight is appropriate for therapeutic doses of LMWH in obese patients. Laboratory monitoring of the anticoagulation effect of LMWHs is generally not necessary, but should be considered in patients with morbid obesity (weight >190 kg), those with severe renal impairment, and those with moderate renal impairment with prolonged (>10 days) LMWH use. When anti-Xa activity is monitored, it should be determined using a chromogenic method and a calibration curve based on the LMWH used.

Conclusions

Additional data are needed for specific dose guiding in obese and renally impaired patients, who are often excluded from larger clinical trials. Practice recommendations are made based on available evidence and authors' clinical opinions.

[Systemic and renal effects of preventing contrast nephrotoxicity with isotonic (0.9%) and hypotonic (0.45%) saline]

INTRODUCTION AND OBJECTIVES

Physiological and hypotonic saline solutions have been used interchangeably for preventing contrast media nephrotoxicity. No analysis of the possible differential effects of the two solutions on the milieu interieur or intercompartmental fluid volumes has been performed. Our aim was to study the systemic and renal effects of two types of saline solution regularly used to prevent contrast media nephrotoxicity in patients undergoing coronary angiography.

METHODS

Changes in electrolyte levels and volume distribution were studied in 71 individuals who were randomized to receive either 0.9% isotonic saline (n=36) or 0.45% hypotonic saline (n=35) during the 12 hours before and after contrast injection (2000 mL in each period).

RESULTS

The creatinine level was elevated equally often in the isotonic and hypotonic saline groups. Isotonic saline administration led to reductions in hemoglobin level, hematocrit and plasma albumin level, and to increases in plasma volume, by 12.3% and 10.4% at 24 and 48 hours, respectively. These changes were significant compared with baseline measurements and compared with the group that received hypotonic saline. Neither of the two saline solutions resulted in a change in plasma atrial natriuretic peptide level. Plasma and urine osmolality decreased only with hypotonic saline. The increase in plasma creatinine level was similar with both isotonic and hypotonic saline.

CONCLUSIONS

During standard therapy for preventing contrast media nephrotoxicity, (1) isotonic saline, but not hypotonic saline, increased plasma volume; (2) this increase did not raise the atrial natriuretic peptide level; and (3) no difference in the increase in serum creatinine level was observed between the two saline solutions. These findings provide evidence that 0.45% saline, at a dose suitable for preventing contrast media nephrotoxicity, is associated with a lower risk of volume expansion. This result is important for patients with severely impaired ventricular function.

Efficacy of N-acetylcysteine and hydration versus placebo and hydration in decreasing contrast-induced renal dysfunction in patients undergoing coronary angiography with or without concomitant percutaneous coronary intervention

OBJECTIVE

Contrast-induced renal dysfunction is an iatrogenic complication that occurs more frequently in patients with preexisting renal dysfunction. A prospective, double-blind, randomized, placebo, controlled trial was completed to assess the efficacy of N-acetylcysteine in decreasing the incidence of contrast-induced renal dysfunction in patients with an acute coronary syndrome and renal insufficiency who underwent coronary angiography with or without percutaneous coronary intervention.

METHODS

With similar intravenous hydration protocols, 20 patients received N-acetylcysteine (treatment group) and 20 patients received placebo (control group) in a twice per day dosing regimen with one dose before and three doses after contrast media exposure.

RESULTS

The two groups were similar at baseline on demographic and clinical characteristics, and preexisting renal insufficiency. Contrast-induced renal dysfunction, defined as an increase in serum creatinine greater than 44 micromol/L (.5 mg/dL) and/or 25% above baseline within 48 hours, occurred in 7.5% of the cohort, with 2.5% in the treatment group, and 5% in the control group, for an absolute difference of 2.5%. There was no difference in serum creatinine or creatinine clearance at 24 hours or at 48 hours between the treatment and control groups.

CONCLUSION

These results suggest that this cohort gained no added protection to renal function with the use of N-acetylcysteine.

Short- and long-term renal outcomes of immediate prophylactic hemodialysis after cardiovascular catheterizations in patients with severe renal insufficiency

BACKGROUND

The short- and long-term effects of prophylactic hemodialysis (HD) immediately after cardiovascular catheterizations on renal function in patients with severe baseline renal insufficiency remain unknown though previous studies reported non-beneficial very-short-term effect in less severe patients.

METHODS AND RESULTS

Patients who had pre-procedural serum creatinine (Scr) between 2.5 and 5.5 mg/dl were retrospectively studied. Twenty of them (14 M/6 F, aged 69 +/- 2 years) had received prophylactic HD after radiocontrast exposure and constituted the HD group. Another 20 patients were case-matched to the baseline demographics of the HD group and served as the non-HD group. The baseline Scr were 3.9 +/- 0.2 and 3.5 +/-0.2 mg/dl, respectively (p = NS). Although the Scr at 3 months was significantly higher in the HD group (4.3 +/- 0.3 vs. 3.4 +/- 0.2 mg/dl, p = 0.02), the absolute and percentage increments from baseline to 3 months (0.4 +/- 0.2 vs. 0.0 +/- 0.2 mg/dl, p = NS, and 11 +/- 5% vs. 1 +/- 7%, p = NS, respectively) and 6 months (0.6 +/- 0.3 vs. 0.4 +/- 0.4 mg/dl, p = NS, and 18 +/- 8% vs. 8 +/- 10%, p = NS, respectively) were not statistically different. Patients who developed end-stage renal disease requiring permanent HD at 1 year were also similar in both groups (four vs. three, respectively, p = NS).

CONCLUSIONS

Our study confirmed that prophylactic HD immediately after contrast media administration in catheterizations failed to affect the short- and long-term renal and clinical outcomes even in patients with severe baseline renal insufficiency.

Clinical and Experimental Evidence for Prevention of Acute Renal Failure Induced by Radiographic Contrast Media

Acute renal failure still occurs as a complication after radiographic examination using iodinated radiocontrast medium. The incidence rate of radiocontrast medium-induced nephropathy (radiocontrast nephropathy) is low (2 - 3%) in general. However, the rate is remarkably elevated in patients with pre-existing renal insufficiency. Radiocontrast nephropathy is associated with increased morbidity and mortality, particularly in patients with percutaneous coronary interventions. Although the reduction in renal blood flow and direct toxic action on renal tubular cells are considered to be involved, little is known about the etiology of radiocontrast nephropathy. A number of agents that improve renal circulation have been clinically tested for prevention of radiocontrast nephropathy, but none of them has succeeded. Protection of renal tubular cells against oxidative stress is another approach to avoid radiocontrast nephropathy. Prophylactic effects of antioxidants such as N-acetylcysteine and ascorbic acid have been reported by several investigators, although the effectiveness of these compounds is still a matter of debate. At present, hydration is regarded as the only effective, though incomplete, prophylactic regimen for radiocontrast nephropathy. Recently, we have shown that caspase-dependent apoptosis is an important factor in the pathogenesis of radiocontrast nephropathy and clarified cellular mechanisms underlying the radiocontrast media-induced apoptosis. This review summarizes clinical and experimental evidence for the etiology and prevention of radiocontrast nephropathy.

Cyclic AMP reverses radiocontrast media-induced apoptosis in LLC-PK1 cells by activating A kinase/PI3 kinase

BACKGROUND

Radiographic contrast material is one of agents that are prone to cause nephropathy, although little is known about cellular mechanisms underlying contrast media-induced renal failure. The present study was designed to determine the role of caspase in contrast media-induced renal injury. The modulation by cyclic adenosine monophosphate (cAMP) of cell injury was subsequently examined.

METHODS

LLC-PK1 cells (a proximal renal tubular cell line of porcine origin) were exposed to diverse contrast media for 30 minutes followed by incubation for 24 hours in normal medium. Cell viability was assessed by mitochondrial enzyme activity and propidium iodide stain. Apoptosis was determined by DNA electrophoresis and annexin V stain. Caspase activity was measured fluorometrically. The mRNA for bax and bcl-2 was determined by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Iodinated and magnetic resonance contrast media reduced cell viability due to apoptosis. The cell damage induced by a non-ionic contrast medium ioversol was inhibited by specific inhibitors for caspase-3 and -9 but not caspase-8. Ioversol enhanced the activities of caspase-3 and -9, but to a lesser extent, caspase-8. The bax mRNA was enhanced, while bcl-2 mRNA was reduced, after exposure to ioversol. All of these actions of ioversol were reversed by dibutyl cAMP in the manner sensitive to a protein kinase A inhibitor H89 and a phosphatidylinositol 3 (PI3) kinase inhibitor wortmannin.

CONCLUSION

We demonstrated for the first time that cAMP reversed caspase-dependent apoptotic renal cell damage caused by contrast media. Both protein kinase A and PI3 kinase might be involved in protective effect of cAMP.

Strategies for Treatment and Prevention of Acute Renal Failure

Acute renal failure (ARF) is a potentially life-threatening medical condition that often complicates the hospitalization of critically ill patients. A variety of therapeutic strategies has been studied for both preventing ischemic and nephrotoxic injury to the kidney and improving renal function in established ARF. This article summarizes the role of pharmacologic therapy in the treatment of ARF. Strategies to reduce extracellular fluid volume and preserve renal function with loop diuretics, low-dose dopamine, and renal replacement therapy will be discussed. The value of preventative therapy has increased, and identifying patients at high risk for development of ARF is critical. Modification of drug regimens, administration of less nephrotoxic medications, and volume expansion prior to nephrotoxin administration can minimize toxicity to the kidney. The search for new agents that can improve survival, decrease the need for renal replacement therapy, and hasten the recovery of renal function in ARF is ongoing.

Renal effects of cardiac angiography with different low-osmolar contrast media

The aim of this study was to evaluate the renal effects of cardiac angiography performed with three low-osmolar contrast media (CM): iopromide (IPR), ioversol (IVR) and ioxaglate (IOX). IPR and IVR are non-ionic CM, IOX is an ionic CM. Different parameters of renal function were determined before and 6, 24, 48, 72 hrs after angiography in 45 patients: 15 patients were examined with IPR, 15 with IVR and 15 with IOX. Glomerular effects--Plasma creatinine increased slightly at the 24th hour after IVR and IOX and at 48 hours after IOP. A significant increase in plasma beta2-microglobulin was observed, at the same time, only after IOX. A significant decrease in creatinine clearance was found at 6 hours after IOX. No significant variations in glomerular filtration rate (GFR) and in effective renal plasma flow were found at 48 hours after cardiac angiography; while filtration fraction was significantly reduced after IOP and IOX. Tubular effects--A marked decrease in sodium clearance and a relevant increase of urinary activities of different tubular enzymes were found after cardiac angiography with all CM, but were more evident after the ionic CM IOX, than after the two non-ionic agents. These tubular effects reached the maximum between 6 and 24 hours and returned to baseline within 72 hrs after cardiac angiography. In conclusion, slight glomerular effects were observed mainly after IOX. A reversible tubular malfunction was found with the three low-osmolar CM and was more evident after ionic CM IOX. thus suggesting that other mechanisms, besides osmolarity, play a role in tubular toxicity due to CM. In no patient did the glomerular and tubular effects of CM have a clinical relevance.

Proximal tubule cell response to radiographic contrast media

Renal dysfunction associated with contrast media (CM) administration is generally attributed to reduced renal blood flow. Studies, however, also suggest direct tubular effects of CM, whose mechanisms remain unclear. This study was conducted to assess the chemotoxic effects of iopamidol, a prototypic CM, on a porcine proximal tubule (PT) cell line, LLC-PK(1) cells. Results indicate that iopamidol did not affect cell viability (determined by trypan blue exclusion and fluorescein staining), but did reduce cell proliferation. Moreover, iopamidol altered mitochondrial function, as determined by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction and mitochondrial membrane potential. Decreased MTT reduction was evident with all CM tested, and its rapid recovery after CM removal suggests that inhibition of mitochondrial function is reversible. Injury to PT cells by iopamidol is supported by the fact that CM increase extracellular adenosine, an indicator of cellular stress. This study provides greater insight into the mechanism underlying the nephrotoxicity induced by contrast in patients and explains the reversibility of this toxicity.

Contrast medium-induced nephrotoxicity: pathophysiology and prevention

Contrast medium-induced nephrotoxicity (CMN) is a common form of iatrogenic acute renal failure. Typically, patients experience changes in serum creatinine or creatinine clearance between 1 and 5 days after exposure to a contrast medium, but they rarely require dialysis. The mechanism for CMN is not understood, but renal insufficiency, dehydration, and congestive heart failure are risk factors. The frequency of CMN with high-osmolality versus low-osmolality media is controversial. Prophylaxis can reduce CMN. Of many different strategies, hydration with normal saline before and after exposure offers the best protection with the fewest adverse effects.

Cyanotic nephropathy and use of non-ionic contrast agents during cardiac catherization in patients with cyanotic congenital heart disease

BACKGROUND

Chronic cyanosis with its associated rheologic changes is a known risk factor for glomerular nephropathy. Therefore, contrast-induced nephrotoxicity should be an important consideration for angiographers comparable to diabetics. On the other hand, progressions in diagnostic and interventional techniques have led to expanded indications and a more widespread use of x-ray contrast agents. The aim of this study was to investigate the risk of contrast-induced nephropathy in the small group of patients with cyanotic heart disease prior to surgical repair.

METHODS

We investigated 23 cyanotic patients with an oxygen saturation of 82 (50-92)%, age 25 (5-63) years, and 13 control subjects with atrial septal defect, age 37 (20-66) years. Blood viscosity was measured before and after cardiac catherization. Renal damage was evaluated by selective analysis of urinary proteins and enzymes.

RESULTS

Before cardiac catheterization, 48% of the cyanotic patients had a moderate glomerulopathy. Cardiac catherization was performed with 3.0 (1.2-6.8) mls/kg non ionic contrast medium. Only one of the 23 patients (4.3%) with normal urinary analysis before cardiac catheterization showed renal damage, which involved tubular and glomerular function. Elevated blood viscosity in cyanotic patients was slightly reduced by the contrast. None of the acyanotic controls had contrast-induced nephropathy.

CONCLUSIONS

The use of non-ionic contrast medium does not worsen cyanotic glomerulopathy. This finding may be due to the reduction of blood viscosity by the application of the contrast medium. The finding of contrast-induced nephropathy in one patient underlines the importance of monitoring renal function after cardiac catheterization.

Effects of the low-osmolality contrast medium ioversol (Optiray) on renal function in a geriatric population

PURPOSE

To assess the incidence of nephrotoxicity following i.v. injection of the iodinated low-osmolality contrast medium ioversol 300 (Optiray) in a geriatric population compared with a control group aged under 60 years, neither group presenting any associated risk factors.

MATERIAL AND METHODS

CT with i.v. bolus injection of ioversol 300 mg I/ml was performed at a mean dose of 1.36+/-0.06 ml/kg (range 1-2 ml/kg b.w.) in 47 patients aged over 69 years. Serum creatinine level was measured and creatinine clearance was calculated at 24, 48 and 72 h after the examination, and compared to a reference serum creatinine value taken before CT. The findings were compared with a control group of 44 patients aged under 60 years.

RESULTS

No significant increase in serum creatinine (+0.6 mmol/l) or in creatinine clearance (+0.7 ml/min) was found during the course of 3 days after the injection. Only one patient (aged 82) presented an increase of 25% in serum creatinine (109 mmol/l).

CONCLUSION

The trial did not demonstrate any significant difference between the 2 groups, although the elderly patients had a subclinical renal impairment revealed by the decrease of the initial creatinine clearance. The use of low-osmolality ioversol makes it possible to perform examination with an iodinated contrast agent without increasing the incidence of nephrotoxicity in elderly subjects.

Severe renal vasoconstriction and anuria after intravenous urography in a patient with renal impairment

Acute renal failure caused by radiocontrast agents remains a severe problem, particularly in patients with risk factors. There is debate concerning the pathophysiology of contrast media-induced acute renal failure, including, but not limited to, renal ischemia or tubular damage. Vascular ischemia is considered a major contributor because consistent changes in renal hemodynamics have been recorded experimentally. We describe a patient who has a typical course of contrast-associated renal failure manifested by severe renal vasoconstriction and backflow of the contrast agent during renal angiography performed after 6 days of an intravenous urography. Such degree of renal vasoconstriction is noteworthy in that this particular case might serve as a model in delineation of the pathogenetic mechanisms of acute renal failure after contrast media administration.

Effects on renal haemodynamics and tubular function of the contrast medium Ioxaglate in renal transplant patients

The aim of this study was to evaluate the effects of Ioxaglate on renal haemodynamics and tubular function in renal transplant patients at increased risk of nephrotoxicity. 21 patients undergoing either intravenous pyelography or arteriography with Ioxaglate were studied. Renal clearance studies were carried out 1 day before and 1 day after administration of Ioxaglate (173 +/- 37 ml) injected into each patient. None experienced any adverse reaction. Mean serum creatinine, glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and urinary NAG excretion were unaltered by ioxaglate. No patient suffered a nephrotoxic reaction or acute oliguria that required dialysis as a result of the administration of contrast material. In the subset of seven patients receiving cyclosporine the same results were observed. In the subset of 10 patients with a GFR lower than 60 ml/min before injection of Ioxaglate were also observed no significant change in mean GFR, ERPF and urinary NAG excretion. Only two patients had a transient decrease of GFR of between 10 and 20%. The results of this study show that the ionic, low osmolar contrast medium ioxaglate may be used safely in patients with a renal transplant thus extending previous data obtained in patients with chronic renal failure.

Biochemical and morphological effects of contrast media on the kidney

The intravenous use of roentgen contrast media (CM) is associated with a low incidence of renal impairment. This paper considers the intravascular handling and retention of CM in relation to effects on renal function - specifically the ability of the kidney to reabsorb and catabolise low molecular weight proteins. Renal morphology following experimental administration of a high dose of an isotonic dimeric CM (iodixanol at 3 g I/kg) in rats showed numerous, large, protein-containing vacuoles or droplets in the cells of the proximal convoluted tubule. These were fully formed within 3.5 hours. The process of vacuole-formation involving the uptake of CM appears to be analogous to dextran uptake that occurs via fluid phase endocytosis. These vacuoles or CM droplets are abundant for 7 days but then slowly decline over several weeks. The quantitative recovery of (14)C iodixanol (3g I/kg) from the kidneys between 3.5 hours to 7 days after administration was about 1% of the dose, with some 0.2% of the original dose still present at 28 days. Subcellular analysis to determine the site of the radiolabel showed that the (14)C was associated with lysosomal marker enzymes. The CM-induced vacuoles/droplets are most probably giant lysosomes, which contain the intracellularly retained CM. Co-administration of tracer doses of (125)I-labelled cytochrome C with iodixanol showed some impairment of low molecular weight protein reabsorption, but remarkably this process was not effected when the vacuoles were fully formed. The conspicuous morphology of the vacuoles, the CM retention and the transient proteinuria and enzymuria cannot presently be associated with any functionally significant impairment of tubular or cellular processes.

Iodinated contrast media-induced nephropathy: pathophysiology, clinical aspects and prevention

Administration of iodinated contrast media (CM) for radiographic purposes is a preoccupying cause of acute renal failure. This review of the literature deals with what is known about physiopathology, clinical course, risk factors and prevention. Factors involved in the pathophysiology of CM-induced acute renal failure are vasoconstriction, direct tubular cell injury and tubular obstruction by casts. In the case of pre-existing renal hypoperfusion, CM may disturb the complex interaction between factors which modulate renal haemodynamics by increasing vasoconstrictor factors, notably endothelin peptides. The renal medulla, a zone characterized by a high metabolic activity and a low oxygen tension, may be a specific target for CM-induced effects. CM-induced nephropathy (CMN) is essentially observed in patients with one or more associated risk factors (chronic renal failure, dehydration, diabetes mellitus with impaired renal function, multiple myeloma, large CM volume, intra-arterial rather than intravenous route, etc). There is much debate as to whether newer low osmolar CM (LOCM) are better tolerated than conventional high osmolar CM (HOCM). Most of the animal studies clearly demonstrate the advantages of LOCM over HOCM. Clinical literature is far more confusing, although some recent studies and one meta-analysis demonstrate that LOCM are better tolerated in patients with impaired renal function. The low number of comparative clinical trials carried out in high risk patients, wide variability in CMN definitions, limited number of patients enrolled and inadequacy of various selected endpoints may explain difficulties experienced in demonstrating this advantage. Furthermore, while hydration is correctly maintained during clinical trials, this is not always true in clinical practice. Such a discrepancy could lead to underestimation of the potential advantage of LOCM over HOCM. Effective prevention should associate the correct hydration of patients, identification and, when possible, optimal correction of risk factors, avoidance of repeated CM injections within a short period of time and temporary disruption of treatment with other nephrotoxic drugs (non steroidal antiinflammatory drugs, aminoglycosides, etc).

Contrast-induced nephrotoxicity in patients undergoing cardiac catheterization

Contrast-induced nephrotoxicity (CIN) is a common concern among angiographers. The causes of CIN are not well understood and the identification and preparation of patients at risk are important. This report reviews the literature concerning the causes and identification of patients at risk and documents the studies that are available to improve the safety of cardiac catheterization and cardiac interventions by reducing the risk of CIN.

Prevention of anaphylactoid reactions in high-risk patients receiving radiographic contrast media

OBJECTIVE

To review various pretreatment regimens for the prophylaxis of anaphylactoid reactions to radiographic contrast media (RCM) in high-risk patients. The proposed etiologies and risk factors for such reactions are also reviewed.

DATA SOURCES

A MEDLINE search of the English-language literature was used to identify pertinent human studies and reviews.

STUDY SELECTION

All studies comparing pretreatment regimens for anaphylactoid reactions to RCM were reviewed as well as studies comparing the incidence of anaphylactoid reactions between lower and higher osmolar RCM.

DATA SYNTHESIS

The two types of reactions to RCM are dose-independent, unpredictable anaphylactoid (pseudoallergic or idiosyncratic) reactions and the dose-dependent, predictable physicochemical (intrinsic, nonidiosyncratic) reactions. Prophylaxis of the former type is targeted at stemming the effects of certain chemical mediators, primarily histamine. The use of lower osmolar RCM is associated with a lower incidence of anaphylactoid reactions compared with higher osmolar RCM, but is significantly more expensive. Risk factors for such reactions are a history of previous anaphylactoid reaction to RCM, asthma, and reaction to skin allergens or penicillin. Discontinuation of any beta-blockers before the procedure is suggested. Pretesting patients with a small amount of RCM has little predictive value for an anaphylactoid reaction. Various pretreatment prophylactic regimens have been studied. Almost all included a corticosteroid to target the inflammatory response and a histamine1 (H1)-antagonist to blunt the effects of histamine. In some clinical trials, ephedrine was added for bronchodilation and cimetidine for its antagonism at the histamine2-receptor. The few controlled clinical trials that have been performed show the combination of prednisone and diphenhydramine to be most beneficial in preventing anaphylactoid reactions to RCM. The addition of ephedrine or cimetidine to a pretreatment regimen remains controversial.

CONCLUSIONS

More controlled clinical studies comparing various pretreatment regimens for high-risk patients need to be performed, especially in patients receiving lower osmolar RCM. Recommendations for high-risk patients who must receive RCM include use of a lower osmolar agent, pretreatment with a corticosteroid and an H1-antagonist, discontinuation of beta-blockers if the patient is taking any, and bedside availability of appropriate medications and equipment to treat anaphylaxis.