What are the causes of low volume pulse?

Low volume pulse is also called as pulsus parvus with pulse pressure <30 mm of Hg

Low volume pulse is seen in the following conditions

• Shock due to any cause eg. acute myocardial infarction, massive haemorrhage, hvpovolacmia.
• Severe aortic stenosis.
• Tight mitral stenosis.
• Pericardial effusion.
• Constrictive pericarditis.
• Congestive cardiac failure.

What is thready pulse?

This a low volume pulse with rapid pulse rate. This pulse is seen in peripheral circulatory failure. Example is cardiogenic shock.

High volume pulse and its causes

High volume pulse is characterised by pulse pressure >60 mm of Hg.

This may be noticed in hyperkinetic states or atherosclerosis

The basic mechanism of high volume pulse is rapid run off of blood from arterial system either to heart, corresponding vein or to capillaries

At cardiac level - Aortic regurgitation(AR)

At Aortic level  - Patent Ductus A rteriosus(PDA)

At arterial level - Arteriovenous fistula

At capillary level- opening up of all capillaries on demand seen in anemia, high fever, thyrotoxicosis, beriberi, cirrhosis liver.

Hyperkinetic circulatory stales like.

• After exercise.
• Pyrexia
• Severe anaemia.
• Aortic incompetence.
• Thyrotoxicosis.
• Arteriovenous communication like patent ductus arteriosus (PDA). Paget's disease etc.
• Chronic corpulmonale.
• Hepatocellular failure.
• Beri-beri.

Atherosclerosis 

In this condition the arteries are rigid, i.e. less compliant: hence there is wide pulse pressure as the systolic blood pressure is high.

Next section : What are the causes of low volume pulse?

What is pulse volume and what are its alterations?

What is volume of the pulse?

It is the amplitude of the pulse wave or the excursion felt at the wrist and usually reflects the pulse pressure (systolic BP minus diastolic BP), It depends on two factors :

• Stroke volume
• Compliance of the arteries.

The carotid, brachial or femoral arteries are more useful for assessing pulse volume and character

than the radial pulse. Normal pulse pressure is 30-60 mm of Hg.

What is pulse pressure and mean pressure?

Pulse pressure is the difference between systolic and diastolic BP (It roughly reflects the volume of the pulse). Mean pressure is approximately the arithmetic mean of diastolic and systolic pressure, and it Is calculated by diastolic pressure plus 1 /3rd of pulse pressure.

When pulse pressure is between 30 to 60mm of Hg pulse volume is normal.

When pulse pressure is less than 30 mm Hg, it is a small volume pulse.

When pulse pressure is greater than 60 mm Hg, it is a large volume pulse.

What are the clinical abnormalities in pulse volume?

• Low volume pulse
• High volume pulse
• Varying volume
• Pulsus alternans
• Pulsus paradoxus

What are the causes of pulse with varying volume?

Varying volume of pulse is due to a combination of low, normal, or high volume pulse in varying manner as a result of varying duration of diastolic filling.

Atrial fibrillation - varying volume with irregular pulse - total irregularity of pulse.

Ventricular tachycardia - varying volume with regular pulse.

Atrial support to ventricular filling is variable.

Next section : High volume pulse and its causes

Different cardiac rhythms

What is sinus rhythm?

SA node is the pacemaker of heart. It generate impulse at a rate of 60 ot 100 per minute.

What is idioventricular rhythm? 

This rhythm is seen when the cardiac impulse arises from the ventricle at the rate of 36 per minute, hence the pulse rate at ventricular rhythm is 36 per minute, this is known as idioventricular rhythm;

What is nodal rhythm ?

When the SA node fails to generate impulse , often the AV node produce the impulse at the rate of 40-60 per minute resulting in a pulse rate of 40-60 per minute.

What are the irregularities in the rhythm ?

Rhvthm is the spacing of successive beats (pulse wave) in time. Normal pulse is regular in rhythm and it is known as sinus rhythm, because it is controlled by the SA node. Irregularities are of two types .

Regularly irregular - i.e. Irregularity comes at regular interval and is seen in extrasystoles. sinus arrhythmia  2nd degree heart block, etc.

Irregularly irregular or completely irregular - i.e. irregularity between two pulse beats in every aspect (volume, spacing etc that is totally chaotic).This is commonly seen in atrial fibrillation, multiple extrasystoles, atrial flutter with varying degrees ol heart block etc.

What is sinus arrhythmia?

Sinus arrhythmia is defined  as increase in pulse rate with inspiration and diminution in pulse rate with expiration. This is a physiological phenomenon commonly observed in children and athletes.

Mechanism of sinus arrhythmia is that the increased amount of blood which comes in the left ventricle in expiration increases the stroke volume. This will immediately stimulates the baroreceptors leading to slowing of the heart rale. Sinus arrhythmia may be absent in autonomic neuropathy and CCF

Bradycardia and its causes

Bradycardia is defined as pulse rate below 60 per minute.

This  is commonly found in the following conditions

Causes of bradycardia

Commonest cause of bradycardia are regular athletic training and myxoedema

Causes of physiological bradycardia

• Athletes
• Sleep

Causes of pathological bradycardia

• Myxoedema
• Obstructive jaundice
• Raised intraocular pressure
• Raised intracranial tension(cushings phenomenon)
• Complete Heart blocks
• Sick sinus syndrome
• Drugs (beta blockers, verapamil,diltiazem, digoxin).
• Severe hypoxia
• Hypothermia

What is  Sinus bradycardia?

In sinus bradycardia the pulse rate is below 60 per minute and  the impulse is originating form the

SA node. The common causes are  all the causes mentioned above in bradycardia except complete heartblock (in CHB. idioventricular rhythm occurs at the rate of 36 per minute)'

What are the causes of bradycardia associated with convulsions ?

• Complete heart block (Stokcs-Adams syndrome).
• Increased intracranial tension due to meningoencephalitis. brain tumour,CVA
• Prior to development of coma in myxoedema. 

What are the variations in pulse rate?

Definition of pulse rate 

It is defined as the number of beats per minute. Normally it ranges between 60 to 100 beats per minute with average 72 beats per minute in an adult. Usually it remains 130 beats per minute at birth.

How to count the pulse rate?

You should count the pulse rate for one full minute by palpating the radial artery 

Normal pulse rate is 60 - 100 per minute

Sinus bradycardia - pulse rate < 60 per minute

Sinus tachycardia - pulse rate > 100 per minute.

What is Tachycardia ?

Tachycardia is defined as pulse rate above 100 per minute. Normally this is found in children.Following are the causes of tachycardia

a. Sinus tachycardia 

Pulse rate is above 100 per minute with the impulse is originating from the SA node. Ihe heart rate in sinus tachycardia varies between 100-160 per minute. The common causes of sinus tachycardia are given below 

Physiological causes of Sinus tachycardia

• Infants
• Children
• Emotion
• Exertion.

Pathological causes of sinus tachycardia 

• High output states: anaemia, fever, beriberi, thyrotoxicosis, pheochromocytoma, arteriovenous fistula. 
• Tachyarrthmias: Supraventricular, ventricular.
• Acute anterior wall myocardial infarction,cardiac failure, cardiogenic shock.myocarditis
• Hypovolemia, hypotension.
• Drugs (atropine, nifedipine, beta agonists salbutamol, thyroxine, catecholamines, nicotine,caffeine).

b.Relative tachycardia 

c. Paroxysmal tachycardia 

Pulse rate is above 160 beats per minute. It is classified  into two types:

1) Supraventricular (PSVT) [atrial (PAT) or nodal (PNT)].

2) Ventricular (VT).

Common causes of paroxysmal tachycardia are the following rheumatic carditis, ischaemic heart disease (1HD). thyrotoxicosis, hypertensive heart disease, cardiomyopathy. WPW syndrome.

How to examine the Pulse ?

What is pulse?

It is the expansion and elongation of arterial wall imparted by the column of blood and is passively produced by the pressure changes during the ventricular systole and diastole.Radial artery pulse is the one commonly examined this is the most accessible peripheral artery.

What are the components of normal arterial pulse?

Percussion wave (P wave ) – It is produced by the ejected amount of blood into the arterial system

Tidal wave (T)- T wave is generated along the arterial wall

Dicrotic wave - formed by the recoil of the vessel

What are the points to note in examination of pulse?

Pulse should always be described under these eiqht points.

• Rate.
• Rhythm.
• Volume.
• Condition ?f the vessel wall.
• Comparison between two radial pulses.
• Radio-femoral delay.
• Any special character.
• Palpation of other peripheral arteries.

How will you examine the pulse?

The radial pulse at the wrist is generally examined using the pulp of three fingers (index, middle and ring linger). The patient’s forearm is held in semipronated position and the wrist is slightly flexed.

Radial artery is used to  palpate the rate and rhythm. 

Carotid artery is used to note the volume and character of the pulse(since it is the’nearest pulse to the aorta)

How to count the Pulse rate?

You should always count the beats for not less than half a minute but in a patient with arrhythmia, one must count the beats for at least one minute.

You can record pulse in the following manner

• Normal +
• Reduced ±
• Absent
• Aneurysmal ++

Next Section : What are the variations in pulse rate?

What is meant by fall by crisis or lysis in fever ?

Fever can subside in the following ways

Crisis

Elevated body temperature settles down to the baseline value immediately after starting treatment. This may be accompanied by diaphoresis, diarrhoea or diuresis.

• Acute lobar pneumonia.
• Rheumatic fever
• Enteric fever with intestinal haemorrhage  or perforation.
• Adrenal crisis (seen in meningococcal meningitis).
• Septicaemic shock.

Lysis 

• Elevated body temperature settles down to normal in step ladder pattern in typhoid fever

What is pyrexia of unknown origin (puo) ?

It is also known as fever of unknown origin (PUO).

Definition of PUO (by Petersdorf and Beeson. 1961) 

• Fever higher than 101°F on several occasions.
• A duration of more than 3 weeks
• Failure to reach a diagnosis by 1 week of inpatient investigation or 3 out patient visit

Classification of PUO by Durack and Street 1991

• Classical PUO
• Nosocomial PUO (hospital-acquired).
• Neutropenic PUO (when neutrophil count is < 500/mnr1)
• HIV-associated (eg. tuberculosis, NHL,drug fever).

What are the diseases which may initially present as PUO 

1.Infections

Tuberculosis, SBE, subphrenic abscess, liver abscess, brucellosis,AIDS and fungal infections

2.Immune causes

Collagen vascular diseases,SLE, rheumatoid arthritis, polyarteritis

3.Factitious fever, drug fever, habitual hyperthermia

4.Malignancy

Lymphomas, leukaemias, multiple myeloma and carcinoma (specially of lungs liver,colon and kidney)

What is periodic fever?

There is periodic attack of fever alternating with a period of apyrexia.This is seen in 

• Pel Ebstein temperature in Hodgkin lymphoma
• Brucellosis.
• Relapsing fever.
• Malaria.
• Rat bite fever.
• Dengue etc.

Appearance of rash in a febrile patient

This article shows temporal association of rash and fever

1st day fever -Chicken pox 

Rash appear in the first day of fever  vesicles are seen mainly in trunk, all forms of vesicles are seen at a time, no umbilication of rash is noticed

2nd day-Scarlet fever 

Rash is seen over chest, neck, scapula; mainlv macular in nature

3rd day - Pox (smallpox) :

It is not seen now-a-days. Rash is peripheral distribution and comes in sequence, umbilication of vescicle are noticed

4th day -Measles

In measles maculo-papular rash over forehead,hairline near ears, face and trunk is seen

5th day -Typhus fever

Macular rash over shoulders, chest, extremities, palms and soles are noticed.

6th day- Dengue fever  

Morbilliform rash  over dorsum of hands and feel, trunk called as white islands in red sea

7th day - Typhoid or enteric fever .

There is rose spots over abdomen, flanks and back: rash is pale-pink in colour and fades on application of pressure

What are the life threatening infection with skin rash

• Meningococcemia
• Dengue hemorrhagic fever
• Rickettsial fever - Rocky Mountain spottcfever
• Septicemia-pseudomonas infection Ecthyma

Relative bradycardia and relative tachycardia

It is known that with every degree (1°F) rise of temperature, the pulse rate is increased by 10 beats/minute.

Relative bradycardia

In this condition, the increase in pulse rate is less than 10 beats/minute with per degree (1°F) rise of temperature.

For example, the pulse rate in relative bradycardia will be about 80/minute, when the temperature is increased by 2°F (actually it should be 92/minutc). 

This is is seen in :

• Any viral fever.
• First week of enteric fever.
• Sometimes in pyogenic meningitis.
• Brucellosis, psittacosis.
• The relative bradycardia in yellow fever is known as Faget's sign.

Relative tachycardia

The increase in pulse rale is more than 10 beats/minute with per degree (1°F) rise of temperature. For example, the pulse rate will be about 120/minute, when the tem-

perature is raised by 3°F (actually it should be 102/minute).

This is seen in :

• Acute rheumatic carditis.
• Tuberculosis.
• Diphtheritic myocarditis.
• Polyarteritis nodosa.

What are the causes of hypothermia ?

Hypothermia can be caused by

• Myxoedema coma.
• Prolonged exposure to cold (in street beggars, accidental or in mountaineering).
• Peripheral circulatory failure due to any cause.
• Enteric fever if associated with haemorrhage or perforation : commonly occurs in the 3rd week
• Panhypopituitarism, adrenal insufficiency.
• Myxedema coma
• Phenobarbitone poisoning
• Exposure to cold ,frost bite
• Alcohol intoxication
• Hypoglycemia
• Artificial hypothermia induced in open heart surgery.

Causes of Herpes labialis (fever blisters) with pyrexia

These are painful and tender vesicles on the outer surface of lips, and is commonlv observed in 

• Acute lobar pneumonia (often gives clue to the side affected and stages of pneumonia)
• Influenza.
• Malaria.
• Meningococcal meningitis.
• Weil's disease.
• Mycoplasma pneumoniae infection.
• AIDS.
• Herpes labialis may be normally seen in females during menstruation.

What is hectic temperature ?

In hectic fever there is a big swing in the body temperature and the temperature rises with chill and rigor, then it persists for few hours and suddenly falls with profuse sweating.

Common causes of hectic fever are :

1.Pent-up pus anywhere in the body

•  Lung abscess
•  Liver abscess
•  Empyema thoracis
•  Empyema of gall bladder
•  Subdiaphragmatic abscess

2.Septicaemia or pyaemia.

3.Rarely in advanced tuberculosis

Fever with patch or membrane in the throat

Fever with patch or membrane seen in the throat in the following conditions

• Acute follicular tonsillitis.
• Candidiasis.
• Diphtheria.
• Agranulocytosis.
• Infectious mononucleosis.
• Vincents angina.

What is chills and rigors?

Chill is a sensation of cold which occurs in most of the fevers.

The normal body temperature is maintained in health by the balance between the heat gain and heat loss by the body that is governed by the Hypothalamus 

Rigor is state of profound chill with piloerection (goose flesh) and is associated with teeth chattering and severe shivering.This shivering is called as rigor

Chills or rigors occur when the thermostat in the hypothalamus, is suddenly reset to a higher temperature due to presence of pyrogens in the body.The body temperature then tends to rise to the newly reset level in the thermostat by conserving heat in the body by the mechanism of cutaneous vasoconstriction and involuntary contraction of skeletal muscles, experienced as chills or rigors. 

When the higher temperature is reached, heat loss starts from the body and the cutaneous vessels dilate to dissipate the heat. Then patient feels hot and sweating starts.

Chills or rigors may be commonly seen with bacterial, rickettsial, protozoal, influenzal infections.

What are the causes of fever with chill and rigor ?

• Malaria.
• Urinary tract infection.
• Pentup pus anywhere in the body (lung abscess, liver abscess etc)
• Septicaemia or pyaemia.
• Cholangitis.
• Subacute bacterial endocarditis.
• Thrombophlebitis.
• Acute pyelitis.
• Acute lobar pneumonia.
• Intravenous fliud infusion or blood transfusion.
• Filariasis.

What is febrile convulsion ?

Young children often develop seizures during the febrile illness and these are short, generalised tonic clonic convulsions.

The characteristics features of febrile convulsions are

• Affects 2-5% of the population of young children.
• Age range of children is between 6 months to 5 years.
• Often there is a positive family history of febrile convulsion.
• Convulsions are not related to the degree of rise of temperature as they may occur even with moderate fever.
• Seizures may last for less than 5 minutes and this is generalised.
• It is not associaled with interictal EEG abnormalities or any neurologic deficit.
  

Management of febrile convulsion

• Management is done by tepid sponge bathing 
• Antipyretics 
• Diazepam (0.2-0.5 mg/kg. I.V).

Predictive factors for recurrence of febrile seizure are the following

• Young age of onset
• Low fever
• Family H/O febrile convulsion 
• Short duration of fever before convulsion.

What are the features of enteric fever in its first week?

Following are the features of enteric fever in the first week

• Step-ladder pattern of pyrexia.
• Frontal headache.
• Constipation.
• Anorexia, nausea, cough and epistaxis.
• Flushed face with toxic look.
• Angry looking tongue, central coating with red tip and margins
• Caecal gurgling.
• Relative bradycardia and rarely dicrotic pulse
• Appearance of rash on the 7th day (usually appears on 7th-10th day).
• The spleen may be just palpable, soft and tender spleen at the end of first week is seen

What is typhoid state ?

If the enteric fever is untreated it may enter into a toxemic phase towards the end of 3 week and is manifested as the following

• Semiconsciousness or unconsciousness.
• Low muttering delirium.
• Coma vigil - Patient lies with half-open eyes but ignorant of his surroundings
• Carphology manifested as picking of bed clothes
• Sub sultus tendinus this is the involuntary movement of the fingers and wrist
• Convulsions rarely.

What is factitious fever ?

Occasionally some patients purposefully show false elevations in body temperature. These patients are usually young women, often they are  attached to health professionals.

They produce rise in body temperature by the following means 

• They may infect themselves with bacteria
• Ingest thyroxine 
• Falsely register higher temperature (after immersing the thermometer in hot water).

The diagnosis is done by.

• Dissociation between pulse and temperature.
• Excessively high temperature (106°F).
• Absence of chills, sweats, tachycardia, tachvpnoea.
• Absence of normal diurnal variation in temperature.