Mannitol is the most widely used osmotic diuretic that is most commonly used to reduce cerebral oedema and intracranial pressure. It is recommended to use mannitol for the reduction of CSF pressure/cerebral oedema in a dose of 0.25-2 g/kg as an intravenous infusion over 30-60 minutes. This can be repeated 1-2 times after 4-8 hours if needed.Mannitol has several contraindications and some of them are listed below:1. Anuria due to renal disease2. Acute intracranial bleeding (except during craniotomy)3. Severe cardiac failure4. Severe dehydration5. Severe pulmonary oedema or congestion6. Known hypersensitivity to mannitol

Juxtapulmonary or ‘J’ receptors are located on alveolar and bronchial walls close to the capillaries. Their afferents are small unmyelinated C-fibres or myelinated nerves in the vagus nerve. Activation causes depression of somatic and visceral activity by producing apnoea or rapid shallow breathing, a fall in heart rate and blood pressure, laryngeal constriction and relaxation of skeletal muscles via spinal neurones. J receptors are stimulated by increased alveolar wall fluid, pulmonary congestion and oedema, microembolism and inflammatory mediators. J receptors are thought to be involved in the sensation of dyspnoea in lung disease.

The beta-adrenoceptors in the heart, peripheral vasculature, bronchi, pancreas, and liver are blocked by beta-adrenoceptor blocking drugs (beta blockers).Beta blockers come in a wide range of strengths, with the choice largely determined by the disease being treated and the patient’s unique circumstances. The intrinsic sympathomimetic activity, lipid solubility, duration of action, and cardioselectivity of beta blockers all differ.Some beta blockers are lipid (lipophilic) soluble, while others are water soluble (hydrophilic). Drugs that are more lipid-soluble are absorbed faster from the gut, undergo more first-pass metabolism, and are eliminated faster. They’re also more likely to get into the brain and cause central effects like insomnia and nightmares. Propranolol, pindolol, labetalol, and metoprolol are examples of lipid-soluble beta blockers. Beta blockers that are water-soluble are less likely to enter the brain and are more resistant to first-pass metabolism. They are excreted by the kidneys, and in renal impairment, dosage reduction is frequently required. Atenolol, nadolol, celiprolol, and sotalol are examples of water-soluble beta blockers.

Hypothyroidism is diagnosed using the results of thyroid function tests (TFTs). In the early stages of the disease, the earliest biochemical change noticed is a rise in thyroid-stimulating hormone (TSH) levels. Free triiodothyronine (T3) and thyroxine (T4) levels are usually normal.In primary hypothyroidism, the serum TSH level is usually greater than 10 mU/L, and free T4 levels are below the reference range.Subclinical hypothyroidism is diagnosed when the serum TSH level is above the reference range, and the free T4 levels are within the reference range. The test should, however, be repeated after 3-6 months to exclude transient causes of raised TSH.In summary, how to interpret TFTs in cases of suspected hypothyroidism is shown below:Subclinical hypothyroidismTSH is raisedFree T4 is normalFree T3 is normalPrimary hypothyroidismTSH is raisedFree T4 is loweredFree T3 is lowered or normalSecondary hypothyroidismTSH is lowered or normalFree T4 is loweredFree T3 is lowered or normal

Adverse effects include:Antimuscarinic effects: Dry mouth, Blurred vision, Constipation, Urinary retention, Sedation, ConfusionCardiovascular effects: Heart block, Arrhythmias, Tachycardia, Postural hypotension, QT-interval prolongation, Hepatic impairment, Narrow-angle glaucoma

Signs and symptoms of Sickle cell disease(SCD):Acute and chronic pain: The most common clinical manifestation of SCD is vaso-occlusive crisis; pain crises are the most distinguishing clinical feature of SCDBone pain: Often seen in long bones of extremities, primarily due to bone marrow infarctionAnaemia: Universally present, chronic, and haemolytic in natureAplastic crisis: Serious complication due to infection with parvovirus B19 (B19V)Splenic sequestration: Characterized by the onset of life-threatening anaemia with rapid enlargement of the spleen and high reticulocyte countInfection: Organisms that pose the greatest danger include encapsulated respiratory bacteria, particularly Streptococcus pneumoniae; adult infections are predominantly with gram-negative organisms, especially SalmonellaGrowth retardation, delayed sexual maturation, being underweightHand-foot syndrome: This is a dactylitis presenting as bilateral painful and swollen hands and/or feet in childrenAcute chest syndrome: Young children present with chest pain, fever, cough, tachypnoea, leucocytosis, and pulmonary infiltrates in the upper lobes; adults are usually afebrile, dyspnoeic with severe chest pain, with multilobar/lower lobe diseasePulmonary hypertension: Increasingly recognized as a serious complication of SCDAvascular necrosis of the femoral or humeral head: Due to vascular occlusionCentral nervous system (CNS) involvement: Most severe manifestation is strokeOphthalmologic involvement: Ptosis, retinal vascular changes, proliferative retinitisCardiac involvement: Dilation of both ventricles and the left atriumGastrointestinal involvement: Cholelithiasis is common in children; liver may become involvedGenitourinary involvement: Kidneys lose concentrating capacity; priapism is a well-recognized complication of SCDDermatologic involvement: Leg ulcers are a chronic painful problem

The metabolism of ethinyl oestradiol and progestogens has been shown to be increased by enzyme-inducing antiepileptics. The oral contraceptive pill (OCP) is less effective in preventing pregnancy as a result of this increased breakdown.Antiepileptic drugs that induce enzymes include:CarbamazepinePhenytoinPhenobarbitalTopiramateAntiepileptics that do not induce enzymes are unlikely to affect contraception. Non-enzyme-inducing anticonvulsants include the following:ClonazepamGabapentinLevetiracetamPiracetamSodium valproate is a type of valproate that is used toLamotrigine is an antiepileptic drug that does not cause the production of enzymes. It does, however, require special consideration, unlike other non-enzyme-inducing antiepileptics. The OCP does not appear to affect epilepsy directly, but it does appear to lower lamotrigine levels in the blood. This could result in a loss of seizure control and the occurrence of seizures.

Type 1 diabetes mellitus results from autoimmune destruction of the insulin-producing beta cells in the islets of Langerhans. This process occurs in genetically susceptible subjects, is probably triggered by one or more environmental agents, and usually progresses over many months or years during which the subject is asymptomatic and euglycemic.

The tidal volume(TV) is the amount of air that moves in and out of the lungs with each respiratory cycle. In a healthy male, the usual volume is 0.5 L (,7 ml/kg body mass).The vital capacity(VC) is the maximum amount of air that can be exhaled following maximal inspiration. The usual volume in a healthy male is 4.5 L.The residual volume(RV) is the amount of air remaining in the lungs after maximum expiration. The usual volume in a healthy male is 1.0 L.The inspiratory reserve volume(IRV) is the maximum amount of air that can be breathed in forcibly after normal inspiration. The usual volume in a healthy male is 3.0 L.The expiratory reserve volume(ERV) is the volume of air that can be breathed out forcibly after normal expiration. The usual volume in a healthy male is 1.0 L.Total lung capacity(TLC) is the volume of air the lungs can accommodate. TLC = RV+VC. The usual volume in a healthy male is 5.5 L.

The clinical effects of Warfarin occur after a dose of greater than 0.5 mg/kg, and they will be observable 8-10 hours after consumption of the drug. The antidote used for Warfarin is Vitamin K.1. In low-risk cases with no apparent bleeding: an oral dose of 10 mg vitamin K2. If there is clinically significant bleedingan intravenous dose of 250-300 mcg/kgActivated charcoal: in cases of warfarin ingestionbinds to it and reduces the absorption of warfarin the ingestion must have occurred within the last hourThere is, however, rarely a need for the use of activated charcoal because vitamin K is such as safe and effective antidote. Clotting studies, including an INR, can be performed, but small children who have ingested warfarin do not require INRs or follow up if they have been treated with 10 mg vitamin K. This dose of vitamin will completely reverse the anticoagulative effects of warfarin.Perform INR if any of the following are present:1. Delayed presentation (>6 hours)2. Patients with symptoms or signs of anticoagulation3. Possible massive ingestion