Month: February 2021

Anatomy of the Respiratory System

When looking into the anatomy of the respiratory system, one needs to take a look at all the components involved in breathing. Through respiration, lungs experience ventilation (breathing), an exchange of gases happens between air and blood and between blood and cells, which cause oxygen perfusion throughout the whole body on a cellular level.

Respiratory System Functions:

  • provides the body with an oxygen supply
  • eliminates carbon dioxide
  • allows gas exchange
  • provides a path to and from the alveoli
  • provides a sense of smell through the olfactory system
  • acts as a humidifier by warming incoming air
  • maintains a balanced pH in the body
  • allows expulsion of abdominal content (such as during childbirth)

The respiratory system can be divided into the following sub-categories:

Upper Respiratory Tract:

Accessed from https://www.physio-pedia.com/Upper_respiratory_airways on 23rd February 2021
  • Nose: includes nostrils (nares), guard hairs (vibrissae, which help prevent insects and large particles from entering the nose), posterior nasal apertures (choanae), nasal cavity, nasal septum (composed of bone and cartilage), nasal fossae, nasal conchae, hard palate, soft palate, paranasal sinuses (which help decrease weight of skull due to its air content), goblet cells, respiratory epithelium of ciliated pseudostratified columnar type, and olfactory epithelium; functions include warming, humidifying and cleansing the inhaled air, providing a sense of smell, and helping in voice amplification.
  • Pharynx: a muscular structure about 5 inches long that acts as a common passageway for food and air consisting of the nasopharynx (lined with pseudostratified columnar epithelium), oropharynx and laryngopharynx (both lined with stratified squamous epithelium, making it a hard surface to be able to tolerate abrasion caused by the swallowing of food); includes an auditory tube, pharyngeal tonsil, palatine tonsils and lingual tonsils (tonsils help combat infection).
  • Larynx: plays an important role in speech through the vocal cords; comprises of 9 rigid hyaline cartilages with a flap of elastic cartilage known as the epiglottis that helps lead air and food into their appropriate pathways.
Accessed from https://sen842cova.blogspot.com/2015/08/pharynx-and-larynx-anatomy.html on 23rd February 2021

Lower Respiratory Tract:

Assessed from https://www.therespiratorysystem.com/category/lower-respiratory-tract/ on 23rd February 2021
  • Trachea: contains c-shaped hyaline cartilage rings that help support it (open parts of ‘c’ face the oesophagus to allow expansion whilst swallowing; lined with ciliated pseudostratified columnar epithelium with a lot of goblet cells that cause mucus production; mucus traps any debris, pushing it upwards through the mucociliary escalator towards the pharynx to be swallowed.
  • Bronchi: formed by the division of the trachea, just beneath the carina; supported by hyaline cartilage with a smooth muscle layered wall. These are further divided into secondary bronchi, one for every lobe within the lungs.
  • Bronchioles: the smallest of all bronchi, which end up with alveolar sacs; do not contain cartilage but are supported by smooth muscle, making them able to dilate or contract to cause bronchodilation or bronchoconstriction.
  • Alveoli: comprised of a single thin layer of squamous alveolar cells that facilitate gas exchange; contain alveolar macrophages (white blood cells) that engulf any bacteria or other debris; great alveolar cells produce a lipid molecule ‘surfactant‘ which coats the alveolar surfaces, preventing the alveoli walls from sticking together, thus allowing them to inflate easily during inhalation; air that enters the alveoli becomes available for gas exchange.
  • Lungs: found within the thoracic cavity; the stroma, which is made of elastic connective tissue, allows the lungs to recoil passively during exhalation; contain the visceral pleura (which ‘hugs’ the lungs), the parietal pleura (the outer layer), both encasing the pleural cavity which contains fluid that helps reduce friction between the lungs and the ribcage while they expand and contract); the two lungs are separated by the mediastinum which is the space found between the two lungs containing the heart, oesophagus and the major blood vessels. The right lung has 2 fissures, forming the superior lobe, middle lobe and inferior lobe. The left lung has 1 fissure, forming the superior lobe and the inferior lobe. The left lung also has the ‘cardiac notch‘, which is the area that houses the heart.

THE CONDUCTING ZONE forms a continuous passageway for air to move in and out of the lungs:

Nose > Pharynx > Larynx > Trachea > Bronchi > Bronchioles > Terminal Bronchioles

THE RESPIRATORY ZONE forms a passageway in which air is exchanged:

Respiratory bronchioles > Alveolar ducts > Alveolar sac

The respiratory membrane consists of squamous alveolar cell, squamous endothelial cell that lines the capillary, and a shared thin basement membrane, all of which help facilitate gas exchange.

Below you can find a collection of videos that can help provide a more visual approach to the anatomy of the respiratory system.

Anatomy of the respiratory System – Animation

https://www.youtube.com/watch?v=kacMYexDgHg

Overview of the Respiratory System – Animation

Lung Anatomy

The Respiratory System

Respiratory System Physiology

Special thanks to the creators of the featured videos on this post, specifically Youtube Channels Alila Medical Media, Registered Nurse RN, KhanAcademyMedicine and Professor Dave Explains.

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Cardioprotective Drugs – Increasing Survival & Decreasing Symptoms

Cardioprotective drugs aim to increase survival and decrease symptoms of cardio-related issues through primary and secondary risk factor prevention. Blood pressure, lipid management, diabetes mellitus and metabolic syndrome are among the targeted concerns. Apart from pharmaceutical therapy, weight management, an increase in physical activity as well as smoking cessation help in providing a total holistic approach for the patient.

Cardioprotective Drugs – Anti-Platelet Therapy

Aspirin 75mg

  • provides an irriversible anti-thrombotic effect that lasts throughout the whole platelet life, which is between 9-10 days
  • provides secondary prevention of cardiovascular events (not to be used as primary prevention due to its increased risk of bleeding

Clopidogrel

  • provides an anti-thrombotic effect which is similar to Aspirin
  • should be given to patients who are allergic to aspirin
  • may be combined with Aspirin and administered post coronary stenting or acute coronary syndrome for a year

Prasugrel

  • should be given to patients unresponsive to Clopidogrel

Cardioprotective Drugs – Beta-Blockers

  • beta-blockers names end with _lol
  • reduce blood pressure and oxygen demand by reducing the heart rate and contractility of the heart
  • reduce symptoms of angina – unless contraindicated, patients with angina requiring regular symptomatic treatment should be prescribed beta blockers
  • possible side effects include bradycardia, worsening of respiratory symptoms such as in asthma and COPD (switching to beta 1 selective agents may help reduce this)
  • erectile dysfunction
  • rebound angina and an increase in cardiac events may be possible if medication is discontinued abruptly

Cardioprotective Drugs – Calcium Channel Blockers

  • improves angina
  • non-dihydropyridines such as Verapamil and Diltiazem help lower the heart rate, reducing contractility, heart rate and AV node conduction, but they may worsen heart failure; may cause side-effects such as bradycardia, conduction disturbances and constipation; can be used with beta-blockers in symptomatic patients (but be careful about possible severe bradycardia)
  • dihydropyridines, including Nifedipine and Amlodipine, may cause side effects such as headaches, flushing and ankle oedema

Cardioprotective Drugs – ACE Inhibitors

  • helps in treating stable angina pectoris as well as related hypertension, diabetes, heart failure, asymptomatic left ventricular dysfunction or MI injury
  • may cause a persistent dry cough, causing some patients to have to switch to an ARB instead
  • rarely causes angioedema

Cardioprotective Drugs – Nitrates

Short-Acting Nitro Glyceral Spray

  • results in vasodilation
  • provides pain relief and anti-ischaemia effects
  • sublingual Nitro Glyceral spray reduces angina pectoris attacks and may also be used in prophylaxis
  • side effects include headache and flushing, as well as possible orthostatic hypotension
  • angina unresponsive to nitroglycerin should be assessed as a possible MI or non-cardiac pain

Long-Acting Nitrates

  • provides relief for symptomatic angina
  • patient tolerance to oral or transdermal nitrates happens fast, thus, nitrate-free intervals are recommended (eg. nitrate patch should be reduced during the night)
  • side effects include headache and orthostatic hypotension

Trimatazidine

  • anti-angina properties
  • side effects include fatigue and drowsiness

Ivabridine

  • preserves AV and intraventricular conduction of the myocardium
  • slows heart rate

Statins

  • used as primary and secondary preventative measures along with healthy lifestyle changes
  • lowers lipid levels, inhibiting cellular cholesterol production, reducing LDL cholesterol by up to 40%, thus accounting to a reduction in coronary events
  • may increase HDL (the ‘good’ cholesterol)
  • reverses endothelial dysfunction, decreases thrombogenicity and reduces inflammation
  • stabilise lipid-rich atherosclerotic plaques, making them less vulnerable to become unstable and possible rupture
  • should be prescribed for all patients with Ischaemic Heart Disease due to their long-term benefits
  • patients with acute coronary syndrome taking statins are less likely to experience a MI or acute arrhythmias
  • patients admitted to hospital with acute coronary syndrome should be prescribed statins independently of their LDL level
  • side effects may include skeletal muscle damage which may be indicated by symptoms, Creatine Kinase level elevation and possibly rhabdomyolysis
  • OTHER LIPID LOWERING DRUGS include Bile Acid Binding Resins, Fibric Acid derivatives, Nicotinic Acid and Ezetimibe

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Cardiac Catheterisation To Diagnose and Treat Cardiovascular Conditions

Cardiac catheterisation is an invasive diagnostic procedure where a catheter is inserted through a peripheral blood vessel to acquire important information about the structure and function of the heart. Through angiography, x-ray images are produced, showing the coronary arteries supplying blood to the myocardium. Treatment of cardiovascular conditions are also possible through cardiac catheterisation.

Cardiac Catheterisation Indications

  • Emergency situation eg. STEMI or NSTEMI presenting with chest pain;
  • Urgent situation eg. STEMI treated with fibrinolysis or NSTEMI;
  • Elective situation eg. in stable coronary artery disease (patient experiences pain during exercise or climbing a flight of steps which goes away after rest – non-urgent situation where planning is possible).

Cardiac Catheterisation Contraindications

  • anaemia
  • electrolyte imbalance
  • uncontrolled hypertension
  • arrhythmias
  • renal impairment
  • allergy to radiographic contrast used in procedure (in which case a different technique may be used)
  • peripheral vascular disease (in this case the best route to be used to advance catheter should be sought)
  • recent cerebrovascular accident
  • severe cardiac failure (in which case patients should NOT be put in supine position due to dyspnoea)
  • coagulopathy (patient could bleed excessively)
  • uncontrolled diabetes mellitus (blood glucose should be controlled prior to the procedure)
  • pregnancy (dye used in procedure could be toxic for the foetus)

Nurse Responsibilities

  • know about the patient’s comorbidities that may increase complication rate
  • allergy history especially to drugs and iodine/seafood
  • know patient haemoglobin level before patient reaches operating table so as to know how to manage bleeding if needed
  • acquire patient signature on consent form
  • explain frequently experienced sensations such as hot flush or metallic taste that comes with the procedure when dye is injected
  • keep patient monitored on ECG with remote defibrillation pads available especially with unstable patients during procedure (a rapid pulse is a normal finding)

Access Route

Cardiac catheterisation is done through the femoral or radial artery. The radial artery is quicker and safer (due to the palmar arch) than the femoral artery since it is wider, making it easier to advance wire through it. It also allows the patient to sit up right after the procedure, whereas in femoral access the patient has to stay on bed rest with the femoral area frequently monitored. However, the femoral artery is still preferred by many operators.

Femoral Arterial Sheats Removal Nurse Responsibilities

Ensure that the patient has been prescribed analgesia prior to sheath removal.

In hypertensive patients, prolonged manual pressure should be applied before sheath removal.

If a haematoma is present, blood flow to the lower limb could be compromised. Thus, the nurse should access the pedal pulse to confirm if blood flow is being impeded. Comparing both limbs and asking the patient to move toes may also help. Manual pressure or through a mechanical device should be used in the case of a haematoma.

Gelafundin, which is a sterile powder indicated in surgical procedures to obtain haemostasis, can be helpful when dealing with a haematoma, however it has an effect on blood pressure. The systolic pressure needs to be less than 90 to use Gelafundin.

Record length and width of haematoma by marking the edges so you can compare later on to confirm whether it is spreading or reducing.

Bleeding

In the case of bleeding from the angio site, occlude femoral artery with manual pressure and assess whether bleeding stops. If it doesn’t stop it means that the bleeding is superficial. In this case apply manual pressure. For mild bleeding apply pressure for 10-20 minutes either using manual pressure or FemoStop, which is a compression device. In the case of major bleeding, a drop in haemoglobin may be noted. This may require blood transfusion. For this reason, the patient should be cross-matched prior to the procedure.

Pseudoaneurysm happens when blood flowing through the tunica media is captured behind the tunica advanticia, which can lead to a rupture due to its weakness. Pseudoaneurysm can cause nerve compression leading to neuralgia.

In retroperitoneal bleeding, which is the result of a ruptured pseudoaneurysm, the patient deteriorates in a very short time, especially since this cavity is very big and can accumulate a large amount of blood which leads to cardiogenic shock. Symptoms of retroperitoneal bleeding include hypotension and severe back pain. It should be reported immediately.

Patient Education

  • apply pressure to femoral site when coughing or sneezing, or if warmth or wetness is felt
  • after femoral sheath removal, patient should stay on bed rest for 4 hours
  • unless contraindicated, fluid intake should be encouraged to promote contrast medium excretion
  • patient should report any bleeding or pain at the angio site immediately

Below you can find a collection of videos that can help provide a more visual approach to cardiac catheterisation.

Cardiac Catheterisation Procedure

Angioplasty Procedure

Cardiac Catheterisation Sheath Removal

FemStop Femoral Artery Compression Device

TR-Band Radial Compression Device

Special thanks to the creators of the featured videos on this post, specifically Youtube Channels Beaumont Health, Fortis Healthcare, Houston Methodist DeBakey CV Education, Nicole McMullen and Radcliffe Group.

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