Pre-hospital Medication Part 1

Gas exchange involves what three processes?

ventilation: movement of air between atmosphere and lungs

diffusion: gas exchange between alveoli and pulmonary capillaries

perfusion: circulation of blood through the pulonary capillaries

what is asthma?

chronic inflammatory disorder of the airways, inflammation results in hyperresponsiveness of the airways to some form of trigger

3 hallmark features that cause obstrction of the small airways and cause the clinical manifestations seen in acute asthma exacerbations

increased mucus secretion

mucosal edema

bronchospasm 

what is chronic bronchitis (COPD)

characterized by hyper-secretion of mucus and chronic productive cough

bronchial irritation results in inflammation of the bronchial epithelium (bronchial edema)

gas exchange is decreased due to inadequate alveolar ventilation 

What is emphysema (COPD)

chronic toxic exposure resuls in destruction of alveolar walls with fewer pulmonary capillaries resulting in impaired gas exchange

with destruction of alveolar walls, there are fewer pulmonary capillaries which can cause cor pulmonale

additionally, the walls the small bronchioles are weakened causing the lungs to lose their elastic recoil and resulting in air-trapping

bronchoconstriction assessment findings

Acute SOB

wheezing on auscultation

audible wheezing

prolonged expiratory phase

decreased air entry

accessory muscle use

salbutamol does what?

stimulates the beta-2 adrenergic receptors of the lungs causing bronchodilation

at higher doses, salbutamol aslo causes some stimulation of beta-1 adrenergic receptors, but to a lesser extent, which could lead to some undesirable affects, what are these?

tachycardia

tremors

anxiety

hypertension

salbutamol’s mode of action

stimulates the beta-2 adrenergic receptors (SNS) selectively to relax bronchial smooth muscle

salbutamol is classified as a?

selective beta-2 agonist

agonist

a drug that binds to a receptor to trigger a response

antagonist

a drug that binds to a receptor to block or prevent an action

adrenergic receptors are?

part of the SNS

important to know adrenergic receptors

alpha-1 (blood vessels)= vasoconstriction

beta-1 (Heart)= cardiac stimulation

beta-2 (lungs)= bronchodilation

salbutamol is also a sympathomimetic, which can?

lower serum potassium levels by shifting extracellular potassium back into cells

increases activity of the sodium potassium pump protein causing more potassium to shift into cells (and sodium out)

epinephrine is?

a catecholamine, an important neurotransmitter/hormone of the SNS and is secreted from the adrenal medulla

epinephrine acts on?

both alpha and beta receptors, non selectively

in the treatment of severe asthma, the primary desired effect is?

stimulation of beta-2 receptors on bronchial smooth muscle, resulting in powerful bronchodilation

increased tidal volume

decreased work of breathing, reduced dyspnea

pathophysiology of anaphylaxis

body respods to a foreign substance and a type 1 hypersensitivity reaction occurs

histamine is released from?

mast cells

which normally will increase blood flow and attract white blood cells to the area of the invading substance, but on a hypersensitivity reaction, histamine is released in large quantities systemically causing anaphylaxis 

widespread histamine release causes

vasodilation

bronchoconstriction

tissue edema

increased capillary permeability

epinephrine has positive inotropic action on?

beta-1 receptors increasing cardiac strength and contractility which increased cardiac output

epinephrine causes?

peripheral vasoconstriction by stimulating alpha receptors

increases blood pressure and tissue perfusion

decreasing edema, reducing capillary leaking

stimulation of beta-2 receptors on bronchial smooth muscle resulting in?

bronchodilation

increasing tidal volume

reducing dyspnea

pathophysiology of croup

viral infection affecting children

immune system and inflammatory response results in mucosal edema and secretions in the subglottic region

airway becomes narrowed and may lead to complete airway obstruction

epinephrine for croup will?

stimulate alpha receptors, resulting in vasoconstriction of upper airway vessels leading to reduced airway edema improving effort of breathing, increasing tidal volume and oxygenation 

does epinephrine cross the blood brain barrier?

no

corticosteroids are produced where?

in the adrenal cortex

glucocorticoids reduce?

inflammation by blocking the messages of inflammatory mediators. they also reduce the immune system response and increase glucose production in the liver

mineralocorticoids such as aldosterone increase?

sodium and water retention, and increase potassium excretion

dexamethasone has both effects from glucocorticoids and mineralocorticoids, but are much more?

glucocorticoid

some examples of corticosteroids 

betamethasone

hydrocortisone

dexamethasone

prednisone

methylprednisolone

prednisolone 

dexamethasone is a?

corticosteroid which binds to glucocorticoid receptors to inhibit inflammatory processes which contribute to the decreased airway diameters that occur in asthma/COPD/croup

corticosteroids are prescribed to?

reduce inflammation and suppress the immune system

can also be used to treat:

rheumatoid arthritis

inflammatory bowel diseases

asthma and COPD

allergies

alpha cells secrete?

glucagon when blood sugar levels are low

beta cells secrete?

insulin when blood suagr levels are high

glucagon increases blood sugar by?

promoting glycogenolysis to break down glycogen into glucose, primarily from the liver stores

promotes gluconeogenesis to produce glucose from non-carbohydrate sources

insulin decreases blood glucose by?

increasing cellular uptake of glucose

promoting glycogenesis to synthesize glycogen from glucose for storage 

Hypoglycemia

may occur in type 1 or type 2 diabetes

characterized by low levels of glucose in the blood

symptoms develop rapidly, may be caused by:

excessive insulin administration

over-exertion for insulin dose

not enough food for insulin dose

pathophysiology of hypoglycemia

nervous system cells require glucose as their energy source and are quickly affected by low levels of glucose in the blood

lack of glucose leads to impaired cellular metabolism of brain cells and there is no alternative (produces characteristic signs/symptoms)

impaired CNS metabolism leads to SNS activation (produces characteristic signs and symptoms, these may be diminished in long-term diabetes or patients taking beta blockers (hypoglycemia unawareness)).

brain damage, seizures, coma may occur if glucose is not supplied to the brain promptly

glucagon for hypoglycemia

glucagon (as a medication) has the same action as the naturally occuring hormone

binds to glucagon receptors on hepatocytes, stimulating the conversion of glycogen to glucose

glycogenolysis- break down of glycogen into glucose

also causes gluconeogenesis 

result is an increase in circulating lucose and resolution of symptoms 

glucagon and a pheochromocytoma

pheochromocytoma is a rare tumour of the adrenal gland

can cause the release of large amounts of catecholamines

SNS activation when the pheochromocytoma is stimulated by glucagon may be overwhelming and the body may be unable to compensate

sulfonylurea toxicity

sulfonylurea medications (glyburide and glipizide are the most commonly prescribed) can be harmful or fatal in accidental overdoses in pediatrics)

these drugs work on pancreatic beta cells to increase insulin secretion and therefore lower blood glucose levels

children are at higher risk of overdose due to reduced glycogen reserve, increased rate of glucose consumption and impaired glycogenolysis and gluconeogenesis