Saturday, October 26, 2013

Studying pediatrics - is it easy?


Pediatrics is a domain of Medicine that deals with child health, illness and well-being . The word "children " may itself may be hard for many doctors, but pediatrics isn't simply about a word. Here the word "Children" includes - neonates, infants, toddlers, shool-age children and adolescents. Every age group has own horizon.



Why studying pediatrics needs a lot of determination and interest?


As we all know, children are not easy to deal with and many people don't have the patience , passion and rest find it hard to built a rapport with children.

Children are scared of white coat and the hospital environment. As soon as they enter, they begin to resist and doctor may have hard time getting his or her co-operation.




Signs are more important than symptoms in pediatrics. Children may not give a subjective complains, instead doctor has to detect his problem. All small children do is cry. A pediatrician has to find a meaning out of his cry.Sometimes it may be a simple colic to as bad as an intussusception or meningitis.

Most difficult thing is the change in biophysiology in children. Right from birth there is daily to monthly change in vitals, clinical findings, reflexes, behavior. Without proper experience detecting an abnormality might be impossible. Pediatric residents have pockets full of growth charts, reference values and drug dosings.
Even the management is totally different in newborn and older children.
Maintainance fluid requirement , nutritional requirement, dose dosing and interval, whether the drug can be used in children, drug formulations- syrup, drops, DT ect makes it mandatory for residents to carry a drug dosage formulation books. There is no fixed dose as in adults.




Another difficult part is the growth and development part. I have seen even pediatrician surrender to this domain. It is a mighty domain and is a core pediatric subject. Even we are pissed off when we encounter a developmental problem case. It is a matter of dedication and patience.

The next is , Congenital anomaly, dysmorphology and spectra of genetic and metabolic diseases that are an
add on to medicine. Dysmorphology is an unrewarding subject. You are a detective and you find the culprit but its unpunishable at most times.There is always a differential when a child is not growing, seriously or recurrently ill or has other problems and it is this part.

The adolescents to say aren't a different species, but its time when they act different. Aggression, rage, frustration, emotions are all exaggerated during this time and taking them in confidence and giving them the right path is the real challenge.

The most important thing is, it is the most sensitive field in medicine. Everyone value children dearer than their life. When a child is critically ill, counselling the parents is harder than the treatment. Breaking a bad news is a different story. Lot of mishaps have occured.

Last but not the least, no matter how ever you are, you have to act funny.

Still, the children make your everyday special. You cannot be a pediatrician and sad. There is only one option. They dazzle you no doubt. So treating these gift of god is a novel job. Pediatrics however difficult may it be, is worth it.

I may be missing points. you are always welcomed to add in.

Saturday, October 12, 2013

Pulmonary Function Test in children- PFT

PFT- The term encompasses a wide variety of objective methods to assess lung function.

1. Ventilatory Lung Function Tests
  • Spirometry
  • Peak Expiratory Flow Rate
  • Helium Dilution technique
  • Body Plethysmography
2.Assessment of Pulmonary Gas Exchange or Diffusion
  • Blood gas analysis
  • Pulse oximetry
  • Measurement of diffusing capacity
3.Assessment of Pulmonary perfusion
  • Methods of measurement of pulmonary circulation
  • Ventilation-Perfusion by Lung Scan


Pulmonary function testing in infants and young children
  • Plethysmography and nasal pneumotachography
  • Blood gas analysis provides the most sensitive index
  • Paediatric pneumogram

Uses of Pulmonary Function Testing in Children
  • Diagnose lung and chest wall disorders
  • Evaluate unexplained dyspnea
  • Identify airway reactivity
  • Evaluate bronchodilator response
  • Assess preoperative lung function
  • Determine course of respiratory failure
  • Assess prognosis
  • Evaluate exercise-related symptoms

Spirometry
Spirometry is a medical test that measures the volume of air an individual inhales or exhales as a function of time. (ATS, 1994)” .John Hutchinson (1811-1861)—inventor of the spirometer and originator of the term vital capacity (VC).
Measurement devices
  • Volume displacement spirometers
  • Flow sensing spirometers
  • Portable devices
Age:
Age : 6 years and above (Spirometry can be reproducibly done from the age of 5 years but these values should be interpreted with individual considering age, sex, height and nutritional status )
Faridi MMA, Gupta P and Prakash A. Lung functions in malnourished children aged five to eleven years. Indian Pedtiatr 1995; 32(1): 35-42

Reference Values
  • Lung volumes and flow rates vary with age, sex and ethnic group. Ideally Every Lab should develop its own Normal values or use data generated from same population.

A spirometer can be used to measure the following:
  • FVC and its derivatives (such as FEV1, FEF 25-75%)
  • Forced inspiratory vital capacity (FIVC)
  • Peak expiratory flow rate
  • Maximum voluntary ventilation (MVV)
  • Slow VC
  • IC, IRV, and ERV
  • Pre and post bronchodilator studies

Read Lung Volumes and Capacities
Procedure
1. Check spirometer calibration.
2. Explain test.
3. Prepare patient-Ask about recent illness, medication use, etc.
4. Give instructions and demonstrate:
  • Show nose clip and mouthpiece.
  • Demonstrate position of head with chin slightly elevated and neck somewhat extended.
  • Inhale as much as possible, put mouthpiece in mouth (open circuit), exhale as hard and fast as possible.
  • Give simple instructions.
5. Patient performs the maneuver
  • Patient assumes the position
  • Puts nose clip on
  • Inhales maximally
  • Puts mouthpiece on mouth and closes lips around mouthpiece (open circuit)
  • Exhales as hard and fast and long as possible
  • Repeat instructions if necessary –be an effective coach
  • Repeat minimum of three times (check for reproducibility)

Special Consideration in children
  • Ability to perform spirometry dependent on developmental age of child, personality, and interest of the child.
  • Patients need a calm, relaxed environment and good coaching. Patience is key.
  • Even with the best of environments and coaching, a child may not be able to perform spirometry

When is the Test Acceptable?
  • A clear start to the test with an apparently maximum effort
  • A smooth, continuous exhalation maintained for at least
  • 6 seconds, without coughing or Valsalva’s maneuver
  • An obvious end to the test (no change in volume for at least 2 seconds)
  • Subject should perform a minimum of three and a maximum of eight FVC maneuvers until at least two acceptable curves are obtained
  • The reproducibility of the two largest curves should be within 5% or 0.1 L, whichever is greater
  • The recorded FVC should be the maximum value from the acceptable curves
Flow is plotted against volume.
Maximum forced expiratory flow (FEF max) is generated in the early part of exhalation, and it is a commonly used indicator of airway obstruction in asthma and other obstructive lesions.
Provided maximum pressure is generated consistently during exhalation, a decrease in flow is a reflection of increased airway resistance.
The total volume exhaled during this maneuver is forced vital capacity (FVC). Volume exhaled in one second is referred to as FEV1. FEV1/FVC is expressed as a percentage of FVC.
FEV 25%-75% is the mean flow between 25% and 75% of FVC and is considered relatively effort independent.
Individual values and shapes of flow-volume curves show characteristic changes in obstructive and restrictive respiratory disorders
  • In intrapulmonary airway obstruction such as asthma or cystic fibrosis, there is a reduction of FEFmax, FEF25%-75%, FVC, and FEV1/FVC. Also, there is a characteristic concavity in the middle part of the expiratory curve.
  • In restrictive lung disease such as interstitial pneumonia, FVC is decreased with relative preservation of airflow and FEV1/FVC. The flow volume curve assumes a vertically oblong shape compared to normal.

Changes in shape of the flow volume loop and individual values depend on the type of disease and the extent of severity.




Approach to Diagnosis:


Click to enlarge
References
  1. Nelson Textbook of Pediatrics, 19 th edition
  2. PEDIATRIC ASTHMA, ALLERGY & IMMUNOLOGY Volume 16, Number 4, 2003 © Mary Ann Liebert, Inc.Basic Pulmonary Function Testing in Children LAURA S. INSELMAN, M.D.
  3. Interpreting pulmonary function tests:Recognize the pattern, and the diagnosis will follow CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 70 • NUMBER 10 OCTOBER 2003
  4. Interpretative strategies for lung function tests Eur Respir J 2005; 26: 948–968 DOI: 10.1183/09031936.05.00035205 CopyrightERS Journals Ltd 2005- ATS/ERS Task Force
  5. American Thoracic Society Documents- An Official American Thoracic Society/European Respiratory Society Statement: Pulmonary Function Testing in Preschool Children
  6. PAEDIATRIC PULMONARY FUNCTION TESTS (PFT) - A Review.- Dhaka
  7. Pulmonary Function Testing in Office Practice Soumya Swaminathan Tuberculosis Research Centre, Indian Council of Medical Research Chetput, Chennai
Submitted by - Dr Sujit Shrestha