Hematochezia: Best Guide To Risky Medications

Gastrointestinal bleeding is a serious issue linked to some medicines. At Liv Hospital, we focus on keeping our patients safe. We follow strict rules to lower the chance of GI bleeding caused by medicines.

Common medications that might lead to GI bleeding include NSAIDs, SSRIs, and warfarin. Research shows these drugs can raise the risk of GI bleeding. This can show up as rectal bleeding or bright red blood in stool.

It’s important to know the risks of these medicines to stop and handle GI bleeding. We aim to give top-notch healthcare and full support to our patients.

Key Takeaways

• NSAIDs, SSRIs, and warfarin are common medications that can cause gastrointestinal bleeding.
• GI bleeding can manifest as rectal bleeding or bright red blood in stool.
• Liv Hospital prioritizes patient safety and adheres to rigorous protocols to minimize GI bleeding risk.
• Understanding the risks associated with certain medications is critical for preventing and managing GI bleeding.
• Comprehensive care and support are essential for patients at risk of medication-induced GI bleeding.

The Scope and Impact of Medication-Induced GI Bleeding

It’s important to know how medication-induced GI bleeding affects us. GI bleeding is serious and can be deadly. It needs quick medical help.

GI bleeding caused by medicine is a big worry for health worldwide. We’ll look at how common it is, its health impact, and the differences between upper and lower GI tract bleeding.

Prevalence and Public Health Significance

GI bleeding often leads to hospital stays, and many cases are due to medicine. Research shows it happens to 40 to 150 people per 100,000 each year. Sadly, up to 10% of these cases can be fatal.

The health issue of GI bleeding is huge. It hurts patients’ lives and costs a lot for healthcare. Here are some important facts about GI bleeding’s impact.

GI Bleeding Type	Annual Incidence (per 100,000)	Mortality Rate (%)
Upper GI Bleeding	50-100	5-10
Lower GI Bleeding	20-50	2-5

Upper vs. Lower GI Tract Bleeding

GI bleeding can happen in the upper or lower GI tract. Upper GI bleeding shows as blood in vomit or black stools. Lower GI bleeding shows as blood in the stool.

Upper GI tract bleeding is more common and often linked to ulcers. Lower GI tract bleeding is more likely from diverticulosis or angiodysplasia. Medicine, like NSAIDs, can cause bleeding in both areas.

Knowing about medication-induced GI bleeding helps us find ways to stop and treat it. This can lead to better health for patients.

Understanding the Pathophysiology of Drug-Induced Mucosal Damage

To understand the risks of medications, we need to know how they damage the mucosa. This knowledge helps us spot risks and find ways to avoid them.

Direct Topical Injury Mechanisms

Some drugs directly harm the GI mucosa. Nonsteroidal anti-inflammatory drugs (NSAIDs) are a big example. They damage the mucosal barrier, leading to ulcers and bleeding.

• NSAIDs block COX enzymes, which are key for the mucosa’s defense.
• Direct contact with NSAIDs irritates and damages the GI mucosa.

Systemic Effects on GI Mucosa

Other drugs affect the GI mucosa systemically. For example, anticoagulants can make bleeding worse by stopping blood clotting.

This is a big problem, even more so with age or existing GI issues.

Disruption of Protective Mechanisms

Drugs can also mess with the GI mucosa’s defenses. Proton pump inhibitors (PPIs), for instance, protect against NSAID ulcers but can upset the gut’s balance.

1. PPIs cut down on stomach acid, which can mess with gut bacteria.
2. Long-term PPI use can lead to fractures and infections.

NSAIDs: Primary Contributors to GI Bleeding

NSAIDs are known for their pain relief and anti-inflammatory effects. But, they also increase the risk of GI bleeding. This risk is due to how NSAIDs affect the lining of the GI tract.

COX-1 Inhibition and Prostaglandin Reduction

NSAIDs mainly work by blocking COX enzymes, like COX-1. This blockage lowers prostaglandin levels. Prostaglandins help protect the GI tract. Without them, the tract is more likely to get damaged and bleed. Studies have shown that less prostaglandin is a big part of why NSAIDs can cause GI problems.

Risk Statistics: 1-4% Developing Ulcers or Bleeding

Using NSAIDs can lead to ulcers or GI bleeding in some people. About 1-4% of users might face these issues. The risk depends on how much and for how long you take NSAIDs, as well as your own health.

NSAID Type	Risk Level	Relative Risk
Traditional NSAIDs	High	2-5 times
COX-2 Inhibitors	Lower	1-2 times
Aspirin (Low-dose)	Moderate	1.5-3 times

Comparative Risks Among Different NSAIDs

Not all NSAIDs are the same when it comes to GI bleeding risk. COX-2 inhibitors are generally safer than traditional NSAIDs. But, the risk can change based on the type of NSAID, how much you take, and your health.

It’s important to think about the benefits and risks of NSAIDs, even more so for those with GI problems or at high risk for bleeding. Knowing these risks helps us make better choices about NSAID use and how to avoid GI problems.

Aspirin Therapy: Balancing Cardiovascular Benefits and GI Risks

It’s important to weigh the heart benefits of aspirin against its risks of stomach problems. Aspirin helps prevent heart attacks and strokes by stopping blood clots. But, it can also lead to bleeding in the stomach.

Low-Dose vs. Full-Dose Aspirin Effects

The dose of aspirin affects its impact on stomach health. Low-dose aspirin, which is 75-100 mg a day, is used to protect the heart. It lowers the risk of heart problems but can also cause stomach bleeding, though less than full-dose aspirin.

Full-dose aspirin, used for pain and inflammation, has a higher risk of stomach problems. Choosing between low-dose and full-dose aspirin depends on the patient’s health and needs.

• Low-dose aspirin: 75-100 mg daily, lower GI bleeding risk
• Full-dose aspirin: higher GI bleeding risk, used for anti-inflammatory effects

Duration-Dependent Risk Factors

How long you take aspirin also matters for stomach health. Long-term use raises the risk of stomach issues. People on aspirin for a long time need regular check-ups for stomach health.

It’s key to think about the long-term effects of aspirin. Treatment plans might need to change to protect the stomach. This could mean using stomach protectors or other heart medicines.

Alternative Antiplatelet Options

For those at high risk of stomach bleeding, other heart medicines might be better. Alternative antiplatelet agents like clopidogrel might be safer for the stomach.

Choosing the right heart medicine depends on the patient’s health. It’s about finding the best balance for their heart and stomach.

1. Assess patient’s cardiovascular risk profile
2. Evaluate GI risk factors
3. Consider alternative antiplatelet therapy if necessary

Anticoagulants and Their Bleeding Risk

Anticoagulants help prevent blood clots but can also cause bleeding in the gut. It’s important to know how different anticoagulants work and their risk of causing bleeding.

0.5-7.0% Annual Major Bleeding Risk with Warfarin

Warfarin has been used for many years to prevent blood clots. But, it can lead to major bleeding in some people. The risk varies from 0.5% to 7.0% each year, based on several factors.

Risk Factors for Warfarin-Induced Bleeding:

• Intensity of anticoagulation
• Patient age
• Comorbid conditions (e.g., renal impairment)
• Concomitant medications (e.g., NSAIDs, antiplatelet agents)

Direct Oral Anticoagulants (DOACs) Comparison

DOACs are newer options compared to warfarin. They offer a more stable effect and don’t need as much monitoring. But, they also have a risk of bleeding.

DOAC	Major Bleeding Risk	GI Bleeding Risk
Dabigatran	3.3%	1.6%
Rivaroxaban	3.6%	2.0%
Apixaban	2.8%	1.1%

Monitoring Parameters and Risk Assessment

Managing anticoagulants well means watching patients closely and assessing risks. For warfarin, checking INR levels regularly is key. DOACs might need less monitoring but require careful patient selection and follow-up.

Knowing the bleeding risks of anticoagulants helps doctors make treatment safer and more effective. This way, they can better protect their patients.

Dangerous Medication Combinations That Increase Bleeding Risk

Some medications together can raise the risk of serious bleeding in the stomach. This is a dangerous condition. We will look at the worst combinations and how alcohol can make bleeding risk higher.

NSAIDs with Anticoagulants

NSAIDs, like ibuprofen and naproxen, can cause stomach ulcers and bleeding. Anticoagulants, like warfarin and dabigatran, prevent blood clots. Taking them together greatly increases the risk of serious bleeding.

Medication Combination	Bleeding Risk
NSAIDs + Anticoagulants	High
NSAIDs alone	Moderate
Anticoagulants alone	Moderate

Triple Therapy: Anticoagulant + Dual Antiplatelet Therapy

Triple therapy is used for some heart conditions. It includes an anticoagulant and two antiplatelet drugs. This mix raises the risk of stomach bleeding a lot. The biggest risk is at the start of using triple therapy.

“The use of triple therapy should be carefully considered, weighing the benefits against the increased risk of bleeding complications.”

Alcohol and Medication Interactions

Drinking alcohol can also increase the risk of stomach bleeding with some medicines. Alcohol can hurt the stomach lining, making it more likely to bleed. People taking anticoagulants or antiplatelet drugs should be careful with alcohol.

Talking to your doctor about your medicines and alcohol is very important. This can help lower the risk of stomach bleeding. Knowing these risks helps patients make better choices about their treatment.

Selective Serotonin Reuptake Inhibitors (SSRIs) and GI Bleeding

The link between SSRIs and GI bleeding is complex. It involves serotonin’s role in platelet function and the risk of bleeding when SSRIs are taken with NSAIDs. We will look into this complex relationship and the factors that raise the risk of GI bleeding in patients on SSRIs.

Serotonin’s Role in Platelet Function

Serotonin is key in platelet aggregation. Platelets release serotonin, which helps in vasoconstriction and platelet aggregation. This is important for stopping bleeding. SSRIs, by stopping serotonin reuptake, can lower platelet serotonin levels. This might impair platelet function and increase bleeding risk.

Studies suggest this mechanism could be why patients on SSRIs have a higher risk of GI bleeding as reported in a study.

Increased Risk When Combined with NSAIDs

Using SSRIs with NSAIDs can greatly increase GI bleeding risk. NSAIDs reduce protective prostaglandins in the GI mucosa, leading to mucosal damage and bleeding. The risk is even higher when SSRIs are added because of their antiplatelet effect. This combination is risky for patients with a history of GI bleeding or other bleeding risk factors.

Medication Combination	Increased Risk of GI Bleeding
SSRIs alone	Moderate
NSAIDs alone	High
SSRIs + NSAIDs	Very High

Specific SSRIs with Higher Bleeding Risk

While all SSRIs carry a risk of GI bleeding, some may have a higher risk. For example, fluoxetine and sertraline are commonly prescribed and linked to a higher risk of GI bleeding. The risk can depend on the SSRI, dosage, treatment duration, and patient-specific factors.

We must carefully consider the benefits and risks of SSRI therapy, mainly for patients at high risk of GI bleeding or those on other medications that increase this risk. It’s important to monitor patients for bleeding signs and adjust treatment as needed to minimize this risk.

Corticosteroids and Their Effects on GI Integrity

Corticosteroids are powerful anti-inflammatory drugs. They can affect the GI system, which is sensitive to many medications. This includes corticosteroids.

Independent vs. Synergistic Effects with NSAIDs

Corticosteroids can harm the GI tract on their own. But, when used with NSAIDs, the risk of GI problems grows. NSAIDs can damage the mucous lining of the GI tract. Adding corticosteroids to the mix makes this risk even higher.

“Using NSAIDs and corticosteroids together raises the risk of GI bleeding,” studies show. Both types of drugs can weaken the GI tract’s protective layer.

Dose and Duration Considerations

The amount and length of time you take corticosteroids matter. Higher doses and longer use can harm the GI tract more.

• Watch for GI problems in patients on long-term corticosteroids.
• Keep doses low to reduce risks.

Preventive Strategies During Steroid Therapy

To lower GI risks with corticosteroids, use preventive steps. This includes gastroprotective drugs, choosing patients wisely, and watching for GI issues early.

Gastroprotective agents like PPIs can help prevent GI bleeding in patients on corticosteroids. This is true, even when NSAIDs are also used.

Knowing how corticosteroids affect the GI tract and using preventive steps can help. This way, we can make treatment safer for everyone.

Hematochezia: A Critical Sign of Lower GI Bleeding from Medications

Lower GI bleeding, shown as hematochezia, is a serious issue. It can be caused by many medications and needs quick medical help. Hematochezia means fresh blood coming out through the anus, showing bleeding in the lower GI tract.

Distinguishing Features from Other GI Bleeding Types

Hematochezia is different from other GI bleeding, like melena. Melena shows as black, tarry stools from upper GI bleeding. Hematochezia points to bleeding in the lower GI tract, like the colon or rectum.

It’s key to know the signs of hematochezia to treat lower GI bleeding right. We must look at the patient’s meds and other factors to find the cause.

Medications Most Associated with Lower GI Bleeding

Many meds raise the risk of lower GI bleeding. These include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Anticoagulants, such as warfarin and direct oral anticoagulants (DOACs)
• Antiplatelet agents, including aspirin and P2Y12 inhibitors

The risk of GI bleeding varies with these meds. It depends on the dose, how long you take it, and your health.

Medication Class	Examples	Risk Factors for Lower GI Bleeding
NSAIDs	Ibuprofen, Naproxen	High dose, long-term use, history of GI bleeding
Anticoagulants	Warfarin, Apixaban	Concomitant use of other anticoagulants or antiplatelets, renal impairment
Antiplatelet Agents	Aspirin, Clopidogrel	Dual antiplatelet therapy, history of GI bleeding

Emergency Warning Signs and Triage

People with hematochezia need quick check-ups. This helps figure out how bad the bleeding is and if they need urgent care. Warning signs include:

• Severe abdominal pain
• Hemodynamic instability (hypotension, tachycardia)
• Significant blood loss (large volume hematochezia)

Spotting these signs fast and acting right is key. It helps manage lower GI bleeding well and avoids bad outcomes.

Proton Pump Inhibitors: Protective or Problematic?

Proton pump inhibitors (PPIs) are often used to prevent GI bleeding. But, their role is more complex than we think. They are key in stopping bleeding in the stomach and intestines, mainly for those on nonsteroidal anti-inflammatory drugs (NSAIDs). Yet, their use is debated.

Paradoxical Risk Increase with NSAIDs

Using PPIs with NSAIDs is common to lower the risk of stomach bleeding. But, studies show this combo might actually raise the risk of bleeding in the lower GI tract. This could be because PPIs change the gut’s bacteria, making it more prone to bleeding.

Key Findings:

• Patients on both PPIs and NSAIDs face a threefold higher risk of lower GI bleeding than those on NSAIDs alone.
• The exact reasons for this are being studied, but changes in gut bacteria are thought to be key.

Appropriate Use Guidelines

To get the most out of PPIs while avoiding risks, following guidelines is key. PPIs should be used at the lowest dose for the shortest time needed. Those on PPIs long-term should be checked regularly to see if they’re really needed.

Recommendations include:

• Lowering PPI doses when possible and regularly reviewing them.
• Exploring other ways to protect the stomach for those at high risk of bleeding.
• Watching for signs of bleeding in those taking both NSAIDs and PPIs.

Alternative Gastroprotective Strategies

For those at risk of bleeding, other protective strategies should be considered. Options include histamine-2 receptor antagonists (H2RAs) or misoprostol. The right choice depends on the patient’s risk factors and medical history.

Alternative Approaches:

Strategy	Description	Indications
H2RAs	Reduce acid secretion	Patients with low to moderate GI bleeding risk
Cytoprotective Agents	Protect GI mucosa	Patients on NSAIDs with high GI bleeding risk

In summary, PPIs are good at preventing bleeding but must be used carefully. By understanding their effects with NSAIDs, following guidelines, and exploring other options, we can better care for those at risk of GI bleeding.

Chemotherapy, Targeted Therapies, and Radiation Effects

Cancer treatments like chemotherapy, targeted therapies, and radiation can harm the GI system. This often leads to mucositis and vascular damage. It’s important to know these effects to better care for patients and avoid bad outcomes.

Mucositis and Vascular Damage Mechanisms

Chemotherapy and radiation can cause mucositis. This is when the GI tract’s lining gets inflamed and ulcers form. It makes swallowing hard, hurts, and raises the chance of infections. Vascular damage also happens, affecting blood vessels and possibly causing bleeding.

The damage comes from harming the cells that line the GI tract and blood vessels. Knowing how this happens helps us find better ways to prevent and treat these problems.

High-Risk Regimens and Agents

Some chemotherapy and targeted therapies are more likely to harm the GI system. High-dose chemotherapy and certain treatments can lead to more mucositis and vascular damage. Spotting these high-risk treatments helps us take steps to protect patients.

Preventive Protocols During Cancer Treatment

Stopping GI toxicity is key in cancer care. We use protective agents and adjust treatments when we can. We also watch closely for any signs of GI problems. Our strategies include giving mucosal protectants, changing chemotherapy doses, and choosing treatments with less GI harm.

By understanding the risks and using preventive steps, we can lessen GI problems in cancer patients.

Antibiotics and GI Bleeding: Beyond C. difficile

Antibiotics can cause GI bleeding, not just from C. difficile. They can harm the mucosa and upset the microbiome. We look into these effects and how to lessen the risks of antibiotic use.

Direct Mucosal Toxicity of Specific Antibiotics

Some antibiotics can directly harm the mucosa, leading to GI bleeding. For example, fluoroquinolones and penicillinscan cause damage. This damage comes from the antibiotic touching the mucosa, causing irritation and bleeding.

The risk of mucosal damage varies by antibiotic type. Knowing these risks helps doctors choose the right antibiotics for patients, even those with GI problems.

Microbiome Disruption and Consequences

Antibiotics upset the balance of the gut microbiome, raising the risk of GI bleeding. The microbiome helps keep the gut lining strong and controls inflammation.

When the microbiome is out of balance, the gut can’t protect itself, leading to bleeding. Restoring the microbiome balancewith probiotics or other treatments can help reduce this risk.

Risk Mitigation Strategies

To lower the risk of GI bleeding from antibiotics, several steps can be taken. First, prescribe antibiotics wisely and only when needed. Also, give gastroprotective agents to high-risk patients to prevent mucosal damage.

• Check if antibiotics are really needed, considering the patient’s history and risk factors.
• Choose antibiotics that are less likely to harm the mucosa.
• Use probiotics or other treatments to support the microbiome.

By understanding the risks of antibiotics and using these strategies, we can lower GI bleeding rates and better care for patients.

Patient Risk Factors That Amplify Medication Bleeding Risk

Medication-induced GI bleeding risk is influenced by patient factors. Certain characteristics can increase the risk of GI bleeding when taking specific medications. Healthcare providers need to understand these risk factors to tailor treatment and minimize adverse effects.

Age-Related Physiological Changes

As we age, our bodies process medications differently. This can increase the risk of GI bleeding. Older adults may have reduced renal function and altered drug metabolism, making them more susceptible to medication side effects.

For example, elderly patients taking NSAIDs are at a higher risk of GI complications. Age-related decline in renal function can lead to drug accumulation, further increasing the risk of bleeding.

Comorbidities: Renal, Hepatic, and Cardiovascular

Patients with comorbid conditions like renal or hepatic impairment are at higher risk of GI bleeding. Renal dysfunction can lead to drug accumulation, while hepatic impairment affects drug metabolism. Cardiovascular diseases may also increase the risk, mainly if anticoagulant or antiplatelet therapies are involved.

Careful consideration of these comorbidities is essential when prescribing medications that may increase the risk of GI bleeding.

Prior GI Bleeding History

A history of previous GI bleeding is a significant risk factor for future bleeding events. Patients who have experienced GI bleeding in the past are more likely to have recurrent bleeding, if exposed to the same medications. Identifying patients with a history of GI bleeding and adjusting their treatment plans is key to preventing future episodes.

“Patients with a history of GI bleeding should be managed with caution when prescribing medications known to increase the risk of bleeding.”

Genetic Factors and Pharmacogenomics

Genetic variations can influence how individuals respond to medications, affecting their risk of GI bleeding. Pharmacogenomics, the study of how genes affect drug response, is becoming more important. Genetic testing may help identify patients at higher risk of bleeding, allowing for personalized treatment strategies.

By understanding and addressing these patient-specific risk factors, healthcare providers can reduce the incidence of medication-induced GI bleeding and improve patient outcomes.

Diagnostic Approach to Suspected Medication-Induced Bleeding

Figuring out if medication is causing stomach bleeding needs a detailed plan. We look at the patient’s meds, lab results, and what the endoscopy shows. This helps us find out why the bleeding is happening.

Laboratory Assessment and Biomarkers

Lab tests are key in finding the cause. We do a CBC to see how bad the bleeding is and check hemoglobin levels. We also check for clotting problems and liver health. Tests like fecal calprotectin help figure out why the bleeding is happening.

A study shows how important labs are in diagnosing stomach bleeding.

Endoscopic Evaluation: Upper and Lower GI

Endoscopy is a big help in finding the source of bleeding. Upper GI endoscopy looks at the esophagus, stomach, and duodenum. Lower GI endoscopy, or colonoscopy, checks the colon and rectum. These tests show things like ulcers or bleeding spots.

Medication Reconciliation and Causality Assessment

Looking at the patient’s meds is vital. We check all their medicines to find out if any are causing the bleeding. Tools like the Naranjo algorithm help us guess if a medicine is the culprit.

Management of Acute Medication-Induced GI Bleeding

Managing acute GI bleeding caused by medications needs a mix of quick actions, changing medications, and helping the patient recover. It’s important to tackle the root cause, keep the patient stable, and avoid more problems.

Immediate Interventions and Medication Adjustments

When a patient shows signs of acute GI bleeding from medication, stop the drug right away. Check if the patient is stable and start helping them if not. This might mean giving fluids, blood, or other support to keep organs working.

Changing medications is key in managing GI bleeding. Stop drugs that can cause bleeding, like anticoagulants or NSAIDs. Sometimes, using proton pump inhibitors can help prevent more bleeding, if the patient is at risk or has had GI issues before.

Endoscopic Treatment Options

Endoscopy is vital in treating acute GI bleeding. It helps find and fix the bleeding spot. Endoscopic treatments like coagulation, clips, or injections can stop the bleeding. The best treatment depends on where, how bad, and why the bleeding is happening.

• Thermal coagulation, like heater probe or argon plasma coagulation, works well for bleeding ulcers.
• Endoscopic clips can seal off bleeding vessels or ulcers.
• Injection therapy helps by clotting or reducing blood flow to the bleeding area.

Resuscitation and Supportive Care

Helping the patient recover and keeping them stable is critical. They might need blood transfusions to replace lost blood and ensure tissues get enough oxygen. Patients with severe bleeding might need to stay in intensive care.

Supportive care also means managing any other health issues that could affect the patient’s overall health. This might involve working with other doctors to make the best care plan.

In summary, treating acute GI bleeding from medications needs a quick and detailed approach. Knowing the right steps, treatments, and care can help save lives.

Prevention Strategies and Patient Monitoring

Preventing GI bleeding linked to certain meds is key. We’ll look at how to do this effectively. This helps doctors manage the risk better.

Risk Stratification Tools

Identifying high-risk patients is vital. Tools and scoring systems help doctors see who’s at risk. They look at age, health conditions, and meds taken.

• Use risk models to spot high-risk patients.
• Look at age and health conditions.
• Check the patient’s medication history for risks.

Appropriate Gastroprotective Regimens

Protecting the stomach is important, more so for those at high risk. The right protection depends on the patient’s risk and the meds they take.

Proton pump inhibitors (PPIs) are often used for protection. But, long-term use can have side effects.

Follow-up Protocols and Surveillance

Regular check-ups and monitoring are key. They help catch GI bleeding early and treat it quickly.

1. See high-risk patients regularly.
2. Watch for signs of GI bleeding.
3. Change prevention plans if needed.

Patient Education and Medication Adherence

Teaching patients about their meds and risks is important. Knowing the risks helps them stick to their meds better.

• Give clear instructions on meds.
• Talk about possible side effects and risks.
• Ask patients to report any symptoms.

With these strategies and careful monitoring, doctors can lower GI bleeding risks from meds.

Conclusion: Optimizing Medication Safety While Managing GI Bleeding Risks

We’ve looked into how different medicines can lead to GI bleeding risks. It’s clear we need a detailed plan for keeping patients safe. Knowing which medicines might cause GI bleeding helps us handle these risks better.

Improving safety means looking at each patient’s unique situation. We consider their age, health conditions, and past bleeding episodes. This helps us create the right plan to prevent bleeding.

To effectively manage GI bleeding risks, we need a few key steps. First, we sort out who’s at higher risk and use protective measures. We also teach patients how to take their medicines right and what to watch for if they start bleeding. By doing this, we can lower the chances of GI bleeding and keep patients safe while using important medicines.

FAQ

References

National Center for Biotechnology Information. Evidence-Based Medical Insight. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK563143/