Preprocedural fasting for contrast-enhanced CT: when experience meets evidence

Debunking myths in radiology: ending pre-contrast fasting

Radiology departments have traditionally observed fasting protocols for patients undergoing radiological studies with intravenous contrast. However, there is no scientific evidence to support these protocols. This practice has potentially harmful consequences, such as interruptions to long-term medication, dehydration, hypoglycaemia, test delays or anxiety, and has no benefits in terms of study interpretation or patient safety. Numerous studies now suggest the need to review these protocols, as reflected in the updated policies of our specialty's main societies, such as the ESUR (European Society of Urogenital Radiology) and the ACR (American College of Radiology). In this article, we review the available scientific evidence on this topic, and present our centre's experience of eliminating fasting prior to contrast-enhanced imaging studies.

Policies and Practices Regarding Preparative Fasting for Contrast-Enhanced Computed Tomography: A Nationwide Survey

OBJECTIVES

To evaluate current policies and practices regarding preparative fasting before contrast-enhanced computed tomography (CECT) and the knowledge and attitudes of radiology head nurses.

METHODS

Radiology head nurses in 499 Chinese hospitals participated in an online survey on preparative fasting for CECT, which mainly included current departmental policies and practices and their knowledge and attitudes.

RESULTS

Response rate was 89.8% (448/499). All surveyed hospitals established preparative fasting protocols, mainly based on guidelines for iodinated contrast media (ICM) usage (68.8%). For the nongastrointestinal CECT scan, the most frequent fasting duration for solid food, semiliquid diet, liquid diet, and clear liquids was 4 to 6 hours (215/422 [50.9%]), less than 6 hours (332/396 [83.8%]), less than 6 hours (275/320, 85.9%), and less than 6 hours (151/189 [79.9%]), respectively. Forty-six percent of the respondents confirmed that unnecessary excessive fasting existed in practice, and the related patient discomfort occurred in 60.3% of the hospitals, mainly manifested as hypoglycemia (86.7%). Expert consensus and guidelines for iodinated contrast media usage (75%) were the leading approach to gain knowledge about preparative fasting; 90.6% of the respondents believed that the clinical scenarios requiring preparative fasting were the upper abdominal examinations. A majority of respondents (72.1%) believed that the current preparative fasting policies needed improvement.

CONCLUSION

Preparative fasting policies varied among hospitals in terms of the fasting content and duration. Respondents' opinions differed on fasting requirements based on various CECT examination sites and patients. The latest guideline regarding no fasting before CECT has not been fully adopted. Further research is required to promote the transformation of guideline evidence.

Fasting before contrast-enhanced CT and the incidence of acute adverse reactions: a single-center randomized clinical trial

OBJECTIVES

To evaluate the effect of eliminating the traditional preparatory fasting policy before contrast-enhanced CT on acute adverse reactions and to identify potential risk factors in a Spanish population sample, since many European patients still experience this unnecessary measure in clinical practice.

METHODS

Outpatients who underwent non-emergency CT to either 6 h of solid food fasting (control group) or an unrestricted consumption of solids (intervention group). Adverse reactions during contrast media administration and up to 30 min afterward were recorded and their incidence was calculated. Using univariate and multivariate logistic regression analyses, various patient-related and technical factors were evaluated to identify risk factors for nausea and vomiting.

RESULTS

One thousand one hundred three patients were evaluated, 560 patients in the control group, and 543 patients in the intervention group. Moderate and severe acute adverse reactions were not identified in either group. No statistical difference was found in the overall acute adverse reactions (hypersensitivity and chemotoxicity) incidence between groups (3.21% vs 2.30% p = 0.36). The total incidence of emetic adverse reactions (nausea and vomiting) was significantly lower in the intervention group than in the control group (0.92% vs 2.86% p = 0.02). Multivariate logistic regression analysis revealed that fasting, age, allergies, neurological diseases, and contrast media concentration were independent risk factors for nausea and vomiting.

CONCLUSION

Unrestricted food intake did not increase the overall incidence of acute adverse reactions and diminished the incidence of nausea and vomiting.

TRIAL REGISTRATION

ANZCTR, ACTRN12623000071628. Registered 23 January 2023-retrospectively registered, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=384985&showOriginal=true&isReview=true .

CRITICAL RELEVANCE STATEMENT

This randomized clinical trial carried out in adults undergoing a non-emergent CT scan demonstrates that fasting as a preparation before a contrast-enhanced CT scan should be discontinued and reserved only for certain specific imaging tests.

KEY POINTS

Despite low osmolar CT contrast media becoming ubiquitous, preparatory fasting is still widely practiced. The overall incidence of acute adverse reactions was unchanged after abolishing preparative fasting. Traditional preparatory fasting should be discontinued and reserved only for certain specific imaging tests.

Relationship between fasting prior to contrast-enhanced CT and adverse reaction in patients with allergies history

AIM

To examine the relationship between fasting prior to contrast-enhanced CT (CECT) and adverse reaction (AR) in patients with allergies history.

MATERIALS AND METHODS

Patients with allergies history who underwent CECT from January 2014 to December 2020 (713 cases with iodinated contrast media (ICM)-related allergy history and 27045 cases with unrelated allergies history) were retrospectively analyzed. The occurrence of ICM-related AR and patient information were recorded. The relationship between fasting and AR and emetic complications was analyzed.

RESULTS

There was no statistical difference in the overall incidence of AR and emetic complications between fasting group and non-fasting group (P>0.05) and fasting was not an influence factor for overall AR occurrence in patients with both ICM-related and unrelated allergies history. However, the incidence of severe AR in fasting group was higher than that in non-fasting group (P=0.01) in patients with unrelated allergies history. The AR incidence in fasting group was higher than that in non-fasting group (P=0.022) when receiving abdominal examinations in patients with unrelated allergies history. There was no statistical difference in the incidence of AR with different occurrence time between fasting group and non-fasting group (P>0.05) in patients with both ICM-related and unrelated allergies history.

CONCLUSIONS

Fasting was associated with higher incidence of severe AR and was associated with higher AR incidence when receiving abdominal examinations in patients with unrelated allergies history. Fasting did not have effects on the occurrence time of AR in patients with allergies history. These provided new guidance for usage of ICM in patients with allergies history.

Pediatric Cardiovascular Computed Tomography: Clinical Indications, Technique, and Standardized Reporting. Recommendations From the Cardiothoracic Taskforce of the European Society of Pediatric Radiology

Congenital heart diseases affect 1% of all live births in the general population. The prognosis of these children is increasingly improving due to advances in medical care and surgical treatment. Imaging is also evolving rapidly to assess accurately complex cardiac anomalies prenatally and postnatally. Transthoracic echocardiography is the gold-standard imaging technique to diagnose and follow-up children with congenital heart disease. Cardiac computed tomography imaging plays a key role in the diagnosis of children with congenital heart defects that require intervention, due to its high temporal and spatial resolution, with low radiation doses. It is challenging for radiologists, not primarily specialized in this field, to perform and interpret these studies due to the difficult anatomy, physiology, and postsurgical changes. Technical challenges consist of necessary electrocardiogram gating and contrast bolus timing to obtain an optimal examination. This article aims to define indications for pediatric cardiac computed tomography, to explain how to perform and report these studies, and to discuss future applications of this technique.

Fasting Versus a Heart-Healthy Diet Before Cardiac Catheterization: A Randomized Controlled Trial

BACKGROUND

Patients undergoing cardiac catheterization are ordered to take nothing by mouth after midnight before their procedure with no evidence to support this practice.

OBJECTIVE

To identify best practice for fasting requirements before cardiac catheterization through comparative evaluation in a prospective randomized controlled study.

METHODS

The study included a convenience sample of 197 patients undergoing elective cardiac catheterization in a progressive inpatient cardiac unit at a regional heart institute in the midwestern United States. The patients were randomized into 2 groups. Patients in the heart-healthy diet group could eat a specified diet with low-acid options until the scheduled procedure. Patients in the fasting group were restricted to nothing by mouth after midnight except for sips of water with medications until the scheduled procedure. Outcome measures included patient-reported satisfaction and complications.

RESULTS

Compared with patients in the fasting group, those in the heart-healthy diet group had significantly more satisfaction with the preprocedural diet. Patients in the heart-healthy diet group had less thirst and hunger before and after the procedure. No patients experienced pneumonia, aspiration, intubation, or hypoglycemia after the procedure. Fatigue, glucose level, gastrointestinal issues, and loading dose of antiplatelet medication did not differ between the groups.

CONCLUSIONS

Allowing patients to eat before elective cardiac catheterization posed no safety risk and benefited patient satisfaction and overall care. The results of this study may help identify best practice for allowing patients to eat before elective procedures using conscious sedation.

Clinical Guidance on the Monitoring and Management of Trastuzumab Deruxtecan (T-DXd)-Related Adverse Events: Insights from an Asia-Pacific Multidisciplinary Panel

Trastuzumab deruxtecan (T-DXd)-an antibody-drug conjugate targeting the human epidermal growth factor receptor 2 (HER2)-improved outcomes of patients with HER2-positive and HER2-low metastatic breast cancer. Guidance on monitoring and managing T-DXd-related adverse events (AEs) is an emerging unmet need as translating clinical trial experience into real-world practice may be difficult due to practical and cultural considerations and differences in health care infrastructure. Thus, 13 experts including oncologists, pulmonologists and a radiologist from the Asia-Pacific region gathered to provide recommendations for T-DXd-related AE monitoring and management by using the latest evidence from the DESTINY-Breast trials, our own clinical trial experience and loco-regional health care considerations. While subgroup analysis of Asian (excluding Japanese) versus overall population in the DESTINY-Breast03 uncovered no major differences in the AE profile, we concluded that proactive monitoring and management are essential in maximising the benefits with T-DXd. As interstitial lung disease (ILD)/pneumonitis is a serious AE, patients should undergo regular computed tomography scans, but the frequency may have to account for the median time of ILD/pneumonitis onset and access. Trastuzumab deruxtecan appears to be a highly emetic regimen, and prophylaxis with serotonin receptor antagonists and dexamethasone (with or without neurokinin-1 receptor antagonist) should be considered. Health care professionals should be vigilant for treatable causes of fatigue, and patients should be encouraged to use support groups and practice low-intensity exercises. To increase treatment acceptance, patients should be made aware of alopecia risk prior to starting T-DXd. Detailed monitoring and management recommendations for T-DXd-related AEs are discussed further.

Hemodynamic effects of intravenous bolus injection of iopromide 370 twice in abdominal contrast-enhanced CT and coronary CTA dual-site sequential examinations

Little information is available about how intravenous bolus injection of iopromide 370 twice in a short time will affect hemodynamics and whether the changes reach clinically relevant levels. In the present study, 31 healthy adult volunteers received abdominal contrast-enhanced CT and coronary CTA sequential examinations. The same dose and rate of normal saline was injected 30 min in advance as self-control. Hemodynamic data were noninvasively collected at selected time points from 1 min prior to injection to 30 min post-injection. The results showed that after iopromide 370 injection, except for stroke volume, all other indicators changed immediately during the first injection, changed most significantly during the second injection (P < 0.05), and returned to baseline within 10 min. Heart rate and cardiac output exhibited the most pronounced changes, with an increasing rate of 33.5% and 33.8%, respectively. For indicators with a change range of > 15% during the second injection, except for mean arterial pressure and total peripheral resistance, the proportions of subjects for the other indicators between the two groups were statistically different (P < 0.05). In conclusion, intravenous bolus injection of iopromide 370 twice in dual-site sequential examinations induced dose-cumulative and time-dependent hemodynamic effects, which all fluctuated within the normal ranges.

Change the preprocedural fasting policy for contrast-enhanced CT: results of 127,200 cases

Objectives

To analyze the relationship between the dietary preparation status prior to contrast-enhanced CT (CECT) and adverse drug reactions (ADR) and emetic complications.

Methods

Non-emergency adult patients who underwent routine CECT in our hospital from January 2019 to December 2020 were retrospectively analyzed. Stratified dietary preparation regimens were implemented for different clinical scenarios. The relationship between actual dietary preparation status and ADR and emetic complications was analyzed.

Results

A total of 127,200 cases were enrolled, including 49,676 cases in the fasting group (57 years ± 13, 56.79% men) and 77,524 cases in the non-fasting group (60 years ± 13, 54.55% men). No statistical difference was found in the overall incidence of ADR (0.211% vs. 0.254%, p = 0.126) or emetic complications (0.030% vs. 0.046%, p = 0.158) between the two groups, and no aspiration pneumonia or death occurred. For patients with an ICM-ADR history, the ADR incidence in non-fasting group was significantly lower than fasting group (2.424% vs. 12.371%, p = 0.002). For patients with hypertension, injection dose ≥ 100 mL, injection rate ≥ 5 mL/s, and Iopromide 370 usage, non-fasting was associated with higher ADR incidence (p < 0.05). 36.67% of the patients experienced unnecessary excessive fasting in practice. Excessive fasting (≥ 10 h) and more water ingestion (≥ 500 mL) within 1 h prior to CECT were associated with higher ADR incidence (p < 0.05).

Conclusion

Unrestricted food ingestion would not increase the overall risk of ADR and emetic complications. For some special patient subgroups, non-fasting, excessive fasting, and more water ingestion were associated with higher ADR incidence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13244-022-01173-z.