To calculate the volume of air in the lungs after a normal relaxed expiration, one can use the formula for functional residual capacity (FRC), which is determined by the balance between the lungs’ tendency to recoil inwards and the chest wall’s tendency to pull outwards. FRC can be calculated by adding the expiratory reserve volume and the residual volume. In individuals with tetraplegia, decreases in FRC are primarily caused by a reduction in the outward pull of the chest wall, which occurs over time due to the inability to regularly expand the chest wall to large lung volumes. This reduction in FRC can increase the risk of atelectasis.

Understanding Lung Volumes in Respiratory Physiology

In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.

Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.

Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.

Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.

Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.

Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.

Lung development in humans begins at week 4 with the formation of the respiratory diverticulum. By week 10, the lungs start to grow as tertiary bronchial buds form. Terminal bronchioles begin to form around week 18. The saccular stage of lung development, which marks the earliest viability for a human fetus, occurs at around 22-24 weeks when type 2 alveolar cells start producing surfactant. By week 30, the primary alveoli form as the mesenchyme surrounding the lungs becomes highly vascular.

The Importance of Pulmonary Surfactant in Breathing

Pulmonary surfactant is a substance composed of phospholipids, carbohydrates, and proteins that is released by type 2 pneumocytes. Its main component, dipalmitoyl phosphatidylcholine (DPPC), plays a crucial role in reducing alveolar surface tension. This substance is first detectable around 28 weeks and increases in concentration as the alveoli decrease in size. This helps prevent the alveoli from collapsing and reduces the muscular force needed to expand the lungs, ultimately decreasing the work of breathing. Additionally, pulmonary surfactant lowers the elastic recoil at low lung volumes, preventing the alveoli from collapsing at the end of each expiration. Overall, pulmonary surfactant is essential in maintaining proper lung function and preventing respiratory distress.

During a median sternotomy, the interclavicular ligament is typically cut to allow access. However, it is important to avoid intentionally cutting the pleural reflections, as this can lead to the accumulation of fluid in the pleural cavity and require the insertion of a chest drain. The pectoralis major muscles may also be encountered, but if the incision is made in the midline, they should not need to be formally divided. It is crucial to be mindful of the proximity of the brachiocephalic vein and avoid injuring it, as this can result in significant bleeding.

Sternotomy Procedure

A sternotomy is a surgical procedure that involves making an incision in the sternum to access the heart and great vessels. The most common type of sternotomy is a median sternotomy, which involves making a midline incision from the interclavicular fossa to the xiphoid process. The fat and subcutaneous tissues are then divided to the level of the sternum, and the periosteum may be gently mobilized off the midline. However, it is important to avoid vigorous periosteal stripping. A bone saw is used to divide the bone itself, and bleeding from the bony edges of the cut sternum is stopped using roller ball diathermy or bone wax.

Posteriorly, the reflections of the parietal pleura should be identified and avoided, unless surgery to the lung is planned. The fibrous pericardium is then incised, and the heart is brought into view. It is important to avoid the left brachiocephalic vein, which is an important posterior relation at the superior aspect of the sternotomy incision. More inferiorly, the thymic remnants may be identified. At the inferior aspect of the incision, the abdominal cavity may be entered, although this is seldom troublesome.

Overall, a sternotomy is a complex surgical procedure that requires careful attention to detail and a thorough understanding of the anatomy of the chest and heart. By following the proper techniques and precautions, surgeons can safely access the heart and great vessels to perform a variety of life-saving procedures.

Syndrome of Inappropriate ADH Secretion

Syndrome of inappropriate ADH secretion (SIADH) is a condition characterized by low levels of sodium in the blood. This is caused by the overproduction of antidiuretic hormone (ADH) by the posterior pituitary gland. Tumors such as bronchial carcinoma can cause the ectopic elaboration of ADH, leading to dilutional hyponatremia. The diagnosis of SIADH is one of exclusion, but it can be supported by a high urine sodium concentration with high urine osmolality.

Hypoadrenalism is less likely to cause hyponatremia, as it is usually associated with hyperkalemia and mild hyperuricemia. On the other hand, diabetes insipidus is a condition where the kidneys are unable to reabsorb water, leading to excessive thirst and urination.

It is important to diagnose and treat SIADH promptly to prevent complications such as seizures, coma, and even death. Treatment options include fluid restriction, medications to block the effects of ADH, and addressing the underlying cause of the condition.

In conclusion, SIADH is a condition that can cause low levels of sodium in the blood due to the overproduction of ADH. It is important to differentiate it from other conditions that can cause hyponatremia and to treat it promptly to prevent complications.

Bronchiectasis can be diagnosed through various methods, including chest radiography, histopathology, and pulmonary function tests.

Chest radiography can reveal thickened bronchial walls, cystic lesions with fluid levels, collapsed areas with crowded pulmonary vasculature, and scarring, which are characteristic features of bronchiectasis.

Histopathology, which is a more invasive investigation often done through autopsy or surgery, can show irreversible dilation of bronchial airways and bronchial wall thickening.

However, high-resolution computerised tomography is a more favorable imaging technique as it is less invasive than histopathology.

Pulmonary function tests are commonly used to diagnose bronchiectasis, but they should be used in conjunction with other investigations as they are not sensitive or specific enough to provide sufficient diagnostic evidence on their own. An obstructive pattern is the most common pattern encountered, but a restrictive pattern is also possible.

Understanding the Causes of Bronchiectasis

Bronchiectasis is a condition characterized by the permanent dilation of the airways due to chronic inflammation or infection. There are various factors that can lead to this condition, including post-infective causes such as tuberculosis, measles, pertussis, and pneumonia. Cystic fibrosis, bronchial obstruction caused by lung cancer or foreign bodies, and immune deficiencies like selective IgA and hypogammaglobulinaemia can also contribute to bronchiectasis. Additionally, allergic bronchopulmonary aspergillosis (ABPA), ciliary dyskinetic syndromes like Kartagener’s syndrome and Young’s syndrome, and yellow nail syndrome are other potential causes. Understanding the underlying causes of bronchiectasis is crucial in developing effective treatment plans for patients.

The maxillary sinus is susceptible to infections due to its drainage from the top. This sinus is the most frequently affected in cases of sinusitis. While frontal sinusitis can lead to intracranial complications, it is still less common than maxillary sinusitis.

The petrosal sinus is not a bone cavity, but rather a venous structure situated beneath the brain.

Acute sinusitis is a condition where the mucous membranes of the paranasal sinuses become inflamed. This inflammation is usually caused by infectious agents such as Streptococcus pneumoniae, Haemophilus influenzae, and rhinoviruses. Certain factors can predispose individuals to this condition, including nasal obstruction, recent local infections, swimming/diving, and smoking. Symptoms of acute sinusitis include facial pain, nasal discharge, and nasal obstruction. Treatment options include analgesia, intranasal decongestants or nasal saline, and intranasal corticosteroids. Oral antibiotics may be necessary for severe presentations, but they are not typically required. In some cases, an initial viral sinusitis can worsen due to secondary bacterial infection, which is known as double-sickening.

Identify the life-threatening features of an asthma attack.

Assessing the severity of asthma attacks in children is crucial for effective management. The 2016 BTS/SIGN guidelines provide criteria for assessing the severity of asthma in general practice. These criteria include measuring SpO2 levels, PEF (peak expiratory flow) rates, heart rate, respiratory rate, use of accessory neck muscles, and other symptoms such as breathlessness, agitation, altered consciousness, and cyanosis.

A severe asthma attack is characterized by a SpO2 level below 92%, PEF rates between 33-50% of the best or predicted, being too breathless to talk or feed, and a high heart and respiratory rate. On the other hand, a life-threatening asthma attack is indicated by a SpO2 level below 92%, PEF rates below 33% of the best or predicted, a silent chest, poor respiratory effort, use of accessory neck muscles, agitation, altered consciousness, and cyanosis.

It is important for healthcare professionals to be familiar with these criteria to ensure prompt and appropriate management of asthma attacks in children. Early recognition of the severity of an asthma attack can help prevent complications and reduce the risk of hospitalization or death.

Based on the results of the Weber and Rinne tests, the patient in the question is likely experiencing conductive hearing loss on the left side. The Weber test revealed that the patient hears sound better on the left side, which could indicate a conductive hearing loss or sensorineural hearing loss on the right side. However, the Rinne test was negative on the left side, indicating a conductive hearing loss. This is further supported by the patient’s reported symptoms of hearing loss in the left ear. This presentation, along with a family history of hearing loss, suggests a possible diagnosis of otosclerosis, a condition that affects the stapes bone and can lead to severe or total hearing loss.

Understanding the Different Causes of Deafness

Deafness can be caused by various factors, with ear wax, otitis media, and otitis externa being the most common. However, there are other conditions that can lead to hearing loss, each with its own characteristic features. Presbycusis, for instance, is age-related sensorineural hearing loss that often makes it difficult for patients to follow conversations. Otosclerosis, on the other hand, is an autosomal dominant condition that replaces normal bone with vascular spongy bone, causing conductive deafness, tinnitus, and a flamingo tinge in the tympanic membrane. Glue ear, also known as otitis media with effusion, is the most common cause of conductive hearing loss in children, while Meniere’s disease is characterized by recurrent episodes of vertigo, tinnitus, and sensorineural hearing loss. Drug ototoxicity, noise damage, and acoustic neuroma are other factors that can lead to deafness.

Understanding the different causes of deafness is crucial in diagnosing and treating the condition. By knowing the characteristic features of each condition, healthcare professionals can determine the appropriate interventions to help patients manage their hearing loss. It is also important for individuals to protect their hearing by avoiding exposure to loud noises and seeking medical attention when they experience any symptoms of hearing loss. With proper care and management, people with deafness can still lead fulfilling lives.

Due to his profession as a builder, this individual is at risk of being exposed to asbestos. Given the 30-year latent period and the presence of a complex effusion, it is highly probable that the underlying cause is mesothelioma.

Understanding Mesothelioma

Mesothelioma is a type of cancer that affects the mesothelial layer of the pleural cavity, which is commonly linked to asbestos exposure. Although it is rare, other mesothelial layers in the abdomen may also be affected. Symptoms of mesothelioma include dyspnoea, weight loss, chest wall pain, and clubbing. In some cases, patients may present with painless pleural effusion. It is important to note that only 20% of patients have pre-existing asbestosis, but 85-90% have a history of asbestos exposure, with a latent period of 30-40 years.

Diagnosis of mesothelioma is typically made through a chest x-ray, which may show pleural effusion or pleural thickening. A pleural CT is then performed to confirm the diagnosis. If a pleural effusion is present, fluid is sent for MC&S, biochemistry, and cytology. However, cytology is only helpful in 20-30% of cases. Local anaesthetic thoracoscopy is increasingly used to investigate cytology negative exudative effusions as it has a high diagnostic yield of around 95%. If an area of pleural nodularity is seen on CT, an image-guided pleural biopsy may be used.

Management of mesothelioma is mainly symptomatic, with industrial compensation available for those who have been exposed to asbestos. Chemotherapy and surgery may be options for those who are operable. Unfortunately, the prognosis for mesothelioma is poor, with a median survival of only 12 months.

Anatomy of the Larynx

The larynx is located in the front of the neck, between the third and sixth cervical vertebrae. It is made up of several cartilaginous segments, including the paired arytenoid, corniculate, and cuneiform cartilages, as well as the single thyroid, cricoid, and epiglottic cartilages. The cricoid cartilage forms a complete ring. The laryngeal cavity extends from the laryngeal inlet to the inferior border of the cricoid cartilage and is divided into three parts: the laryngeal vestibule, the laryngeal ventricle, and the infraglottic cavity.

The vocal folds, also known as the true vocal cords, control sound production. They consist of the vocal ligament and the vocalis muscle, which is the most medial part of the thyroarytenoid muscle. The glottis is composed of the vocal folds, processes, and rima glottidis, which is the narrowest potential site within the larynx.

The larynx is also home to several muscles, including the posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, vocalis, and cricothyroid muscles. These muscles are responsible for various actions, such as abducting or adducting the vocal folds and relaxing or tensing the vocal ligament.

The larynx receives its arterial supply from the laryngeal arteries, which are branches of the superior and inferior thyroid arteries. Venous drainage is via the superior and inferior laryngeal veins. Lymphatic drainage varies depending on the location within the larynx, with the vocal cords having no lymphatic drainage and the supraglottic and subglottic parts draining into different lymph nodes.

Overall, understanding the anatomy of the larynx is important for proper diagnosis and treatment of various conditions affecting this structure.

Effective pain management is crucial after a tonsillectomy to promote the consumption of food and fluids.

Prescribing analgesics and encouraging oral intake is the best course of action. This will alleviate pain and enable the patient to eat and drink, which is essential for a speedy recovery.

Starting maintenance fluids or partial nutritional feeds, obtaining IV access, or waiting for two hours before reviewing the patient are not the most appropriate options. Analgesia should be the primary consideration to facilitate oral fluid therapy and promote healing.

Tonsillitis and Tonsillectomy: Complications and Indications

Tonsillitis is a condition that can lead to various complications, including otitis media, peritonsillar abscess, and, in rare cases, rheumatic fever and glomerulonephritis. Tonsillectomy, the surgical removal of the tonsils, is a controversial procedure that should only be considered if the person meets specific criteria. According to NICE, surgery should only be considered if the person experiences sore throats due to tonsillitis, has five or more episodes of sore throat per year, has been experiencing symptoms for at least a year, and the episodes of sore throat are disabling and prevent normal functioning. Other established indications for a tonsillectomy include recurrent febrile convulsions, obstructive sleep apnoea, stridor, dysphagia, and peritonsillar abscess if unresponsive to standard treatment.

Despite the benefits of tonsillectomy, the procedure also carries some risks. Primary complications, which occur within 24 hours of the surgery, include haemorrhage and pain. Secondary complications, which occur between 24 hours to 10 days after the surgery, include haemorrhage (most commonly due to infection) and pain. Therefore, it is essential to weigh the benefits and risks of tonsillectomy before deciding to undergo the procedure.

Trismus, which is difficulty in opening the mouth, is a common symptom of peritonsillar abscess (also known as quinsy). It is important to note that quinsy is a complication of tonsillitis, not acute tonsillitis itself. Epiglottitis may present with muffled voice, drooling, and difficulty in breathing, while infectious mononucleosis is associated with other symptoms such as weight loss, fatigue, and enlarged lymph nodes and organs.

Peritonsillar Abscess: Symptoms and Treatment

A peritonsillar abscess, also known as quinsy, is a complication that can arise from bacterial tonsillitis. This condition is characterized by severe throat pain that is localized to one side, along with difficulty opening the mouth and reduced neck mobility. Additionally, the uvula may be deviated to the unaffected side. It is important to seek urgent medical attention from an ENT specialist if these symptoms are present.

The treatment for a peritonsillar abscess typically involves needle aspiration or incision and drainage, along with intravenous antibiotics. In some cases, a tonsillectomy may be recommended to prevent recurrence of the abscess. It is important to follow the recommended treatment plan and attend all follow-up appointments to ensure proper healing and prevent complications.

The phrenic nerves, located in the anterior region of the lung’s hilum, play a crucial role in keeping the diaphragm functioning properly. These nerves have both sensory and motor functions, and any issues in the sub diaphragmatic area may result in referred pain in the shoulder.

The Phrenic Nerve: Origin, Path, and Supplies

The phrenic nerve is a crucial nerve that originates from the cervical spinal nerves C3, C4, and C5. It supplies the diaphragm and provides sensation to the central diaphragm and pericardium. The nerve passes with the internal jugular vein across scalenus anterior and deep to the prevertebral fascia of the deep cervical fascia.

The right phrenic nerve runs anterior to the first part of the subclavian artery in the superior mediastinum and laterally to the superior vena cava. In the middle mediastinum, it is located to the right of the pericardium and passes over the right atrium to exit the diaphragm at T8. On the other hand, the left phrenic nerve passes lateral to the left subclavian artery, aortic arch, and left ventricle. It passes anterior to the root of the lung and pierces the diaphragm alone.

Understanding the origin, path, and supplies of the phrenic nerve is essential in diagnosing and treating conditions that affect the diaphragm and pericardium.

If a patient presents with raised serum ACE levels, sarcoidosis should be considered as a possible diagnosis. The combination of erythema nodosum and bilateral hilar lymphadenopathy on a chest x-ray is pathognomonic of sarcoidosis. Lung cancer is unlikely in a young patient without a significant smoking history, and tuberculosis would require recent foreign travel to a TB endemic country. Multiple myeloma would not cause the same symptoms as sarcoidosis. Exposure to organic material would not be a likely cause of raised serum ACE levels.

Understanding Sarcoidosis: A Multisystem Disorder

Sarcoidosis is a condition that affects multiple systems in the body and is characterized by the presence of non-caseating granulomas. The exact cause of this disorder is unknown, but it is more commonly seen in young adults and individuals of African descent.

The symptoms of sarcoidosis can vary depending on the severity of the condition. Acute symptoms may include erythema nodosum, bilateral hilar lymphadenopathy, swinging fever, and polyarthralgia. On the other hand, insidious symptoms may include dyspnea, non-productive cough, malaise, and weight loss. Additionally, some individuals may develop skin symptoms such as lupus pernio, while others may experience hypercalcemia due to increased conversion of vitamin D to its active form.

Sarcoidosis is also associated with several syndromes, including Lofgren’s syndrome, Mikulicz syndrome, and Heerfordt’s syndrome. Lofgren’s syndrome is an acute form of the disease that typically presents with bilateral hilar lymphadenopathy, erythema nodosum, fever, and polyarthralgia. Mikulicz syndrome is characterized by enlargement of the parotid and lacrimal glands due to sarcoidosis, tuberculosis, or lymphoma. Finally, Heerfordt’s syndrome, also known as uveoparotid fever, presents with parotid enlargement, fever, and uveitis secondary to sarcoidosis.

In conclusion, sarcoidosis is a complex disorder that can affect multiple systems in the body. While the exact cause is unknown, early diagnosis and treatment can help manage symptoms and improve outcomes.

Opiate Overdose

Opiate overdose is a common occurrence that can lead to slowed breathing, inadequate oxygen saturation, and CO2 retention. This classic picture of opiate overdose can be reversed with the use of naloxone. The condition is often caused by the use of illicit drugs and can have serious consequences if left untreated.

Diagnosis of Bronchial Carcinoma

The patient’s medical history indicates the possibility of bronchial carcinoma. The most appropriate initial investigation to confirm this diagnosis is a chest x-ray. Other tests such as blood cultures may not be useful for an apyrexial patient. However, additional investigations may be considered after the chest x-ray. It is important to prioritize the chest x-ray as the first line investigation to detect any abnormalities in the lungs. Proper diagnosis is crucial for timely treatment and management of bronchial carcinoma.

The respiratory alkalosis observed in the arterial blood gas results is most likely a result of hyperventilation, as indicated by the patient’s medical history.

Arterial Blood Gas Interpretation: A 5-Step Approach

Arterial blood gas interpretation is a crucial aspect of patient care, particularly in critical care settings. The Resuscitation Council (UK) recommends a 5-step approach to interpreting arterial blood gas results. The first step is to assess the patient’s overall condition. The second step is to determine if the patient is hypoxaemic, with a PaO2 on air of less than 10 kPa. The third step is to assess if the patient is acidaemic (pH <7.35) or alkalaemic (pH >7.45).

The fourth step is to evaluate the respiratory component of the arterial blood gas results. A PaCO2 level greater than 6.0 kPa suggests respiratory acidosis, while a PaCO2 level less than 4.7 kPa suggests respiratory alkalosis. The fifth step is to assess the metabolic component of the arterial blood gas results. A bicarbonate level less than 22 mmol/l or a base excess less than -2mmol/l suggests metabolic acidosis, while a bicarbonate level greater than 26 mmol/l or a base excess greater than +2mmol/l suggests metabolic alkalosis.

To remember the relationship between pH, PaCO2, and bicarbonate, the acronym ROME can be used. Respiratory acidosis or alkalosis is opposite to the pH level, while metabolic acidosis or alkalosis is equal to the pH level. This 5-step approach and the ROME acronym can aid healthcare professionals in interpreting arterial blood gas results accurately and efficiently.

Suspect Meniere’s disease in a patient presenting with vertigo, tinnitus, and fluctuating sensorineural hearing loss. Acoustic neuroma would present with additional symptoms such as facial numbness and loss of corneal reflex. Herpes Zoster Oticus (Ramsey Hunt syndrome) would present with facial palsy and a painless rash. Vestibular neuronitis would have longer episodes of vertigo, nausea, and vomiting, but no hearing loss. Benign paroxysmal positional vertigo would have brief episodes of vertigo after sudden head movements.

Meniere’s disease is a condition that affects the inner ear and its cause is unknown. It is more commonly seen in middle-aged adults but can occur at any age and affects both men and women equally. The condition is characterized by the excessive pressure and progressive dilation of the endolymphatic system. The main symptoms of Meniere’s disease are recurrent episodes of vertigo, tinnitus, and sensorineural hearing loss. Vertigo is usually the most prominent symptom, but patients may also experience a sensation of aural fullness or pressure, nystagmus, and a positive Romberg test. These episodes can last from minutes to hours and are typically unilateral, but bilateral symptoms may develop over time.

The natural history of Meniere’s disease is that symptoms usually resolve in the majority of patients after 5-10 years. However, most patients will be left with some degree of hearing loss, and psychological distress is common. ENT assessment is required to confirm the diagnosis, and patients should inform the DVLA as the current advice is to cease driving until satisfactory control of symptoms is achieved. Acute attacks can be managed with buccal or intramuscular prochlorperazine, and admission to the hospital may be required. Prevention strategies include the use of betahistine and vestibular rehabilitation exercises, which may be beneficial.

The patient’s medical history suggests that they may be suffering from alpha-1 antitrypsin deficiency.

When there is a shortage of alpha-1 antitrypsin, neutrophil elastase is not inhibited and can break down proteins in the lung interstitium. Although neutrophil elastase is a crucial part of the innate immune system, its unregulated activity can lead to excessive breakdown of extracellular proteins like elastin, collagen, fibronectin, and fibrin. This results in reduced pulmonary elasticity, which can cause emphysema and COPD.

Alpha-1 antitrypsin (A1AT) deficiency is a genetic condition that occurs when the liver does not produce enough of a protein called protease inhibitor (Pi). This protein is responsible for protecting cells from enzymes like neutrophil elastase. A1AT deficiency is inherited in an autosomal recessive or co-dominant manner and is located on chromosome 14. The alleles are classified by their electrophoretic mobility, with M being normal, S being slow, and Z being very slow. The normal genotype is PiMM, while heterozygous individuals have PiMZ. Homozygous PiSS individuals have 50% normal A1AT levels, while homozygous PiZZ individuals have only 10% normal A1AT levels.

A1AT deficiency is most commonly associated with panacinar emphysema, which is a type of chronic obstructive pulmonary disease (COPD). This is especially true for patients with the PiZZ genotype. Emphysema is more likely to occur in non-smokers with A1AT deficiency, but they may still pass on the gene to their children. In addition to lung problems, A1AT deficiency can also cause liver issues such as cirrhosis and hepatocellular carcinoma in adults, and cholestasis in children.

Diagnosis of A1AT deficiency involves measuring A1AT concentrations and performing spirometry to assess lung function. Management of the condition includes avoiding smoking and receiving supportive care such as bronchodilators and physiotherapy. Intravenous alpha1-antitrypsin protein concentrates may also be used. In severe cases, lung volume reduction surgery or lung transplantation may be necessary.

The area of the vocal cords lacks lymphatic drainage, making it a lymphatic boundary. The upper portion above the vocal cords drains to the deep cervical nodes through vessels that penetrate the thyrohyoid membrane. The lower portion below the vocal cords drains to the pre-laryngeal, pre-tracheal, and inferior deep cervical nodes. The aryepiglottic and vestibular folds have a significant lymphatic drainage and are prone to early metastasis.

Anatomy of the Larynx

The larynx is located in the front of the neck, between the third and sixth cervical vertebrae. It is made up of several cartilaginous segments, including the paired arytenoid, corniculate, and cuneiform cartilages, as well as the single thyroid, cricoid, and epiglottic cartilages. The cricoid cartilage forms a complete ring. The laryngeal cavity extends from the laryngeal inlet to the inferior border of the cricoid cartilage and is divided into three parts: the laryngeal vestibule, the laryngeal ventricle, and the infraglottic cavity.

The vocal folds, also known as the true vocal cords, control sound production. They consist of the vocal ligament and the vocalis muscle, which is the most medial part of the thyroarytenoid muscle. The glottis is composed of the vocal folds, processes, and rima glottidis, which is the narrowest potential site within the larynx.

The larynx is also home to several muscles, including the posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, vocalis, and cricothyroid muscles. These muscles are responsible for various actions, such as abducting or adducting the vocal folds and relaxing or tensing the vocal ligament.

The larynx receives its arterial supply from the laryngeal arteries, which are branches of the superior and inferior thyroid arteries. Venous drainage is via the superior and inferior laryngeal veins. Lymphatic drainage varies depending on the location within the larynx, with the vocal cords having no lymphatic drainage and the supraglottic and subglottic parts draining into different lymph nodes.

Overall, understanding the anatomy of the larynx is important for proper diagnosis and treatment of various conditions affecting this structure.

The only answer that causes a leftward shift in the oxygen dissociation curve is hypothermia. When tissues undergo aerobic respiration, they generate heat, which changes the shape of the haemoglobin molecule and reduces its affinity for oxygen. This results in the release of oxygen at respiring tissues. In contrast, lower temperatures in the lungs cause a leftward shift in the oxygen dissociation curve, which increases the binding of oxygen to haemoglobin.

Hypercapnia is not the correct answer because it causes a rightward shift in the oxygen dissociation curve. Hypercapnia lowers blood pH, which changes the shape of haemoglobin and reduces its affinity for oxygen.

Hypoxaemia is not the correct answer because the partial pressure of oxygen does not affect the oxygen dissociation curve. The partial pressure of oxygen does not change the affinity of haemoglobin for oxygen.

Increased concentration of 2,3-diphosphoglycerate (2,3-DPG) is not the correct answer because higher concentrations of 2,3-DPG reduce haemoglobin’s affinity for oxygen, causing a right shift in the oxygen dissociation curve.

Understanding the Oxygen Dissociation Curve

The oxygen dissociation curve is a graphical representation of the relationship between the percentage of saturated haemoglobin and the partial pressure of oxygen in the blood. It is not influenced by the concentration of haemoglobin. The curve can shift to the left or right, indicating changes in oxygen delivery to tissues. When the curve shifts to the left, there is increased saturation of haemoglobin with oxygen, resulting in decreased oxygen delivery to tissues. Conversely, when the curve shifts to the right, there is reduced saturation of haemoglobin with oxygen, leading to enhanced oxygen delivery to tissues.

The L rule is a helpful mnemonic to remember the factors that cause a shift to the left, resulting in lower oxygen delivery. These factors include low levels of hydrogen ions (alkali), low partial pressure of carbon dioxide, low levels of 2,3-diphosphoglycerate, and low temperature. On the other hand, the mnemonic ‘CADET, face Right!’ can be used to remember the factors that cause a shift to the right, leading to raised oxygen delivery. These factors include carbon dioxide, acid, 2,3-diphosphoglycerate, exercise, and temperature.

Understanding the oxygen dissociation curve is crucial in assessing the oxygen-carrying capacity of the blood and the delivery of oxygen to tissues. By knowing the factors that can shift the curve to the left or right, healthcare professionals can make informed decisions in managing patients with respiratory and cardiovascular diseases.

The muscles of the ansa cervicalis are: GenioHyoid, ThyroidHyoid, Superior Omohyoid, SternoThyroid, SternoHyoid, and Inferior Omohyoid. The mylohyoid muscle is innervated by the mylohyoid branch of the inferior alveolar nerve. A mnemonic to remember these muscles is GHost THought SOmeone Stupid Shot Irene.

The ansa cervicalis is a nerve that provides innervation to the sternohyoid, sternothyroid, and omohyoid muscles. It is composed of two roots: the superior root, which branches off from C1 and is located anterolateral to the carotid sheath, and the inferior root, which is derived from the C2 and C3 roots and passes posterolateral to the internal jugular vein. The inferior root enters the inferior aspect of the strap muscles, which are located in the neck, and should be divided in their upper half when exposing a large goitre. The ansa cervicalis is situated in front of the carotid sheath and is an important nerve for the proper functioning of the neck muscles.

The expiratory reserve volume refers to the maximum amount of air that can be exhaled after a normal breath out. It is important to note that this volume can be reduced in conditions that limit lung expansion, such as obesity and ascites. Obesity, in particular, can cause a restrictive pattern on spirometry, where the FEV1/FVC ratio is ≥0.8. Other restrictive lung conditions include idiopathic pulmonary fibrosis, pleural effusion, ascites, and neuromuscular disorders that limit chest expansion. On the other hand, obstructive disorders like asthma and COPD lead to a FEV1/FVC ratio of <0.7, limiting the amount of air that can be exhaled in one second. It is essential to understand the different lung volumes and capacities, including inspiratory reserve volume, tidal volume, expiratory reserve volume, residual volume, inspiratory capacity, vital capacity, functional residual capacity, and total lung capacity. Understanding Lung Volumes in Respiratory Physiology In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured. Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml. Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration. Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV. Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume. Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.

Bird fanciers’ lung is caused by avian proteins found in bird droppings, which can lead to hypersensitivity pneumonitis. This is a type of pulmonary disorder that results from an inflammatory reaction to inhaling an allergen, which can be organic or inorganic particles such as animal or plant proteins, certain chemicals, or microbes. Similarly, other types of lung diseases such as tobacco worker’s lung, farmer’s lung, and hot tub lung are also caused by exposure to specific allergens in the environment.

Extrinsic allergic alveolitis, also known as hypersensitivity pneumonitis, is a condition that occurs when the lungs are damaged due to hypersensitivity to inhaled organic particles. This damage is thought to be caused by immune-complex mediated tissue damage, although delayed hypersensitivity may also play a role. Examples of this condition include bird fanciers’ lung, farmers lung, malt workers’ lung, and mushroom workers’ lung. Symptoms can be acute or chronic and include dyspnoea, dry cough, fever, lethargy, and weight loss. Diagnosis is made through imaging, bronchoalveolar lavage, and serologic assays for specific IgG antibodies. Management involves avoiding the triggering factors and oral glucocorticoids.

The function of alpha-1 antitrypsin is to inhibit elastase. However, smoke has a negative impact on this protein in the lungs, resulting in increased activity of elastases and the breakdown of elastic tissue, which leads to emphysema.

Contrary to popular belief, smoke actually activates polymorphonuclear leucocytes, which contributes to the development of emphysema.

Mucous gland hyperplasia, basal cell metaplasia, and basement membrane thickening are all examples of how smoke affects the lungs to cause chronic bronchitis, not emphysema.

COPD, or chronic obstructive pulmonary disease, can be caused by a variety of factors. The most common cause is smoking, which can lead to inflammation and damage in the lungs over time. Another potential cause is alpha-1 antitrypsin deficiency, a genetic condition that can result in lung damage. Additionally, exposure to certain substances such as cadmium (used in smelting), coal, cotton, cement, and grain can also contribute to the development of COPD. It is important to identify and address these underlying causes in order to effectively manage and treat COPD.

The ansa cervicalis muscles can be remembered using the acronym GHost THought SOmeone Stupid Shot Irene. These muscles include the GenioHyoid, ThyroidHyoid, Superior Omohyoid, SternoThyroid, SternoHyoid, and Inferior Omohyoid. The ansa cervicalis is made up of a superior and inferior root, which originate from C1, C2, and C3. The superior root begins where the nerve crosses the internal carotid artery and descends in the anterior triangle of the neck. The inferior root joins the superior root in the mid neck region and can pass either superficially or deep to the internal jugular vein.

The ansa cervicalis is a nerve that provides innervation to the sternohyoid, sternothyroid, and omohyoid muscles. It is composed of two roots: the superior root, which branches off from C1 and is located anterolateral to the carotid sheath, and the inferior root, which is derived from the C2 and C3 roots and passes posterolateral to the internal jugular vein. The inferior root enters the inferior aspect of the strap muscles, which are located in the neck, and should be divided in their upper half when exposing a large goitre. The ansa cervicalis is situated in front of the carotid sheath and is an important nerve for the proper functioning of the neck muscles.

To calculate the total lung capacity, one can add the vital capacity and residual volume. For example, if the vital capacity is 3300 mL and the residual volume is 1200 mL, the total lung capacity would be 4500 mL. It is important to note that tidal volume, inspiratory capacity, and the FEV1/FVC ratio are other measurements related to lung function. Residual volume refers to the amount of air left in the lungs after a maximal exhalation, while total lung capacity refers to the volume of air in the lungs after a maximal inhalation.

Understanding Lung Volumes in Respiratory Physiology

In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.

Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.

Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.

Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.

Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.

Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.

Side Effects of Buproprion

Buproprion is a medication that can cause aggression and hallucination in some patients. However, the more common side effects are gastrointestinal disturbances such as diarrhoea, nausea, and dry mouth. These side effects are often experienced by patients taking buproprion. It is important to be aware of the potential side effects of any medication and to speak with a healthcare provider if any concerns arise. Additional information on buproprion and its potential side effects can be found in the electronic Medicines Compendium and Medicines Complete.

The Epley manoeuvre is a treatment for BPPV, while the Dix-Hallpike manoeuvre is used for diagnosis. The Epley manoeuvre aims to move fluid in the inner ear to dislodge otoliths, while the Dix-Hallpike manoeuvre involves observing the patient for nystagmus when swiftly lowered from a sitting to supine position. Tinel’s sign is positive in those with carpal tunnel syndrome, where tapping the median nerve over the flexor retinaculum causes paraesthesia. The Trendelenburg test is used to assess venous valve competency in patients with varicose veins.

Benign paroxysmal positional vertigo (BPPV) is a common cause of vertigo that occurs suddenly when there is a change in head position. It is more prevalent in individuals over the age of 55 and is less common in younger patients. Symptoms of BPPV include dizziness and vertigo, which can be accompanied by nausea. Each episode typically lasts for 10-20 seconds and can be triggered by rolling over in bed or looking upwards. A positive Dix-Hallpike manoeuvre, which is indicated by vertigo and rotatory nystagmus, can confirm the diagnosis of BPPV.

Fortunately, BPPV has a good prognosis and usually resolves on its own within a few weeks to months. Treatment options include the Epley manoeuvre, which is successful in around 80% of cases, and vestibular rehabilitation exercises such as the Brandt-Daroff exercises. While medication such as Betahistine may be prescribed, it tends to have limited effectiveness. However, it is important to note that around half of individuals with BPPV may experience a recurrence of symptoms 3-5 years after their initial diagnosis.

The correct answer is 5600ml, which represents the total lung capacity. This value is obtained by adding the vital capacity, which is the maximum amount of air that can be breathed out after a deep inhalation, to the residual volume, which is the amount of air that remains in the lungs after a maximal exhalation. The vital capacity is composed of three volumes: the inspiratory reserve volume, the tidal volume, and the expiratory reserve volume. Other formulas are available to calculate different lung volumes, but they are not as commonly used.

Understanding Lung Volumes in Respiratory Physiology

In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.

Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.

Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.

Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.

Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.

Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.