Medical research Specificity

Specificity refers to the value of measuring the proportion of negatives that medical practitioners have correctly identified in a binary classification. In the medical field, one can represent specificity by the proportion of medically fit people who have been correctly identified as lacking a certain condition, also referred to as the true negative rate (Dower 394).
Also known as the recall or true positive rate, sensitivity represents the value of measure of correctly identified proportions that are of actual positives. An example of a sensitivity value is the percentage of correctly identified ill people as having a certain condition (Dower 394).
Positive predictive value
This represents the proportion of positive results in diagnostic and statistical tests, which represents a true positive result. It can also be defined in form of a formula as shown below.
PPV= number of true positives/ (number of true positives + number of false positives) =number of true positives/ number of positive calls
Negative predictive value
It refers to the proportion of negative result in a diagnostic and statistics test, which is a true negative result. In formula form, the negative predictive value can be represented as follows:
NPV=number of true negatives/ (number of true negatives + number of false negatives) =number of true negatives/ number of negative calls.
A true positive and true negative represent the events that a test makes positive or negative and the subject`s result is either positive or negative under the gold standard respectively.
A false positive and negative represent the event on which a test makes a positive and negative prediction while the subject has a negative or positive result under the gold standard respectively.
Both the PPV and NPV represent show the performance of a statistical measure or diagnostic test. A high output result signifies the accuracy of that particular statistic (Dower 394).
In a study done to assess the validity of CPSS for stroke in an urban health agency on emergency services, the main objective was to determine the effectiveness of Prehospital stroke screens when classifying patients deemed to have suffered stroke. The secondary objective was to identify the differences in the specificity and sensitivity of the two Prehospital stroke screens that were assessed. Out of the 416 patients enrolled in the study, 44.7% (186 patients) of them were determined to have stroke. A sensitivity of 0.790 was recorded with a confidence level of 95 % at interval of between 0.672 and 0.802. the specificity of the CPSS was 0.239 with a 95% confidence interval 0.187-0.300). This study yielded a low sensitivity and specificity as CPSS performed better in one of the above metrics. The positive predictive value of at least an abnormality was 0.53 while the negative predictive value was at 0.62.( “Result Filters.” National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 12 Jan. 2014. Paramedic reading of ECGs
An electrocardiogram otherwise known as ECG is a device, which records the electrical activities that happen in the heart. The device records the electrical signals over numerous heartbeats and releases an ECG strip, which paramedics can read and interpret. Through each beat, the heart undergoes depolarization that triggers its contraction. This forms an electrical activity that is transmitted all over the body and hence can be collected as data through the skin. In reading an n ECG, a paramedic has to understand the ECG tracing and be able to identify the distinct QRS complex. Every interpretation revolves around the correct assessment of the rhythm, axis and rate. In determining if, a person is sinus rhythm or not, the paramedic observes the P waves that appear before the QRS complex when the patient is sinus rhythm (Trivedi, Schuur and Cone 159). If the P waves are absent, the regularity of the QRS complexes are noted with the corresponding width or narrowness. The axis represents the net direction that an n electrical activity of the heart assumes during its depolarization. It is a measurement that once grasped can be instantaneously calculated. It can be altered by the right and left ventricular hypertrophy. The reading and interpretation of the ECG is a complex undertaking that requires that paramedics practice a lot in order to become efficient and more knowledgeable on them. It is possible for paramedics to effectively read and interpret the results from an electrocardiogram through frequent training, drills and practice. Through various studies and researches done, it has been proved that cardiology can be interpreted from the electrical readings obtained from the readings of the electrocardiogram (Macartney 656).
Complications of back-boarding patients:
Long backboards are used to retrieve and ferrying injured persons from rubbles, rivers or scenes of accidents to an ambulance or medical attention. Movement is more restricted once on the ambulance stretcher. The underlying fact is that spinal immobilization results into more pain an anxiety for almost every patient. By lying on the backboard, the patients usually suffer from back pains brought about by the hardness of the board. The sores resulting from the pressure of the backboard and the resulting tenderness may affect the quality of the subsequent radiological imaging and hence a clearer assessment of the patient`s condition may be unascertainable. This may lead to a complete miss of an underlying factor that may present a big danger to the life of such a patient (Peery, Andrew, Brice, and William 294). Immobilization of patients with gunshot wounds and other forms of penetrating trauma presents challenges regarding the passage of air where emphasis is placed on the airway and management of their breathing while also ensuring that the patient is taken to a trauma center rapidly. An unsecured airway presents a bigger danger than the wound or spinal injury may have on the patient. A respiratory compromise presents a big challenge that should be handled delicately while also taking care of the primary injury to the patient.
Most of the complications arising from the backboard are in relation to the already existing injury conditions of the patients. The backboards present an inadequate form of spinal immobilization that may lead to worsening of the already existing injuries during movement and removal of the patients from the boards. Increased aggravation of the existing injuries may lead to irrecoverable and irreversible damage to body parts which may be life threatening (Chan 293).
Prehospital needle thoracostomy
Prehospital needle thoracostomy is a procedure that is performed to decompress a patient`s chest in an event where the patient is getting worse due to a tension pneumothorax (Trajstman 501). The needle is inserted on the pneumothorax`s side. This procedure involves the insertion of a needle into the chest through the ribs, a process that is determined by the chest wall thickness of the patient. A cannula is then cast off into the chest through the needle just like inserting an IV, and then into its hub. After the cannula is cast off, the needle is removed as one listens for the ejection of air resulting from the tension pneumothorax (Eckstein and Suyehara 134). A flutter valve is then attached to the cannula using tubing present in the set available. After this, pressure ventilation is applied positively to expand the lung again and then a chest tube is inserted as the catheter is removed. The chest tube is connected to the suction point in order to re-expand the lung. Prehospital needle thoracostomy is necessary to alleviate the danger posed by a tension pneumothorax immediately. Case reports point towards the needle size as the major cause of failure of this technique. By using a variable needle size in decompression, this technique may enjoy a better success rate among patients of all age groups (Givens 796). Following these guidelines, needle thoracostomy presents an effective means of decompressing a tension pneumothorax if the right tools and procedure are strictly followed (Mines and Abbuhl 864).
Works cited
Chan, D. “Backboard Versus Mattress Splint Immobilization: A Comparison Of Symptoms Generated.” Journal of Emergency Medicine 14.3 (1996): 293-298. Print.
Dower, G. “Polarcardiographic Sensitivity And Specificity.” Journal of Electrocardiology 9.4 (1976): 394-394. Print.
Eckstein, Marc, and Deborah Suyehara. “Needle Thoracostomy In The Prehospital Setting.” Prehospital Emergency Care 2.2 (1998): 132-135. Print.
Givens, Melissa L.. “Needle Thoracostomy: A Cautionary Note – In Reply.” academic emergency medicine11.7 (2004): 796-796. Print.
Macartney, F. J. “How To Read Pediatric ECGs.” Archives of Disease in Childhood56.8 (1981): 656-656. Print.
Mines, D, and S Abbuhl. “Needle Thoracostomy Fails To Detect A Fatal Tension Pneumothorax.” Annals of Emergency Medicine 22.5 (1993): 863-866. Print.
Peery, Charles Andrew, Jane Brice, and William D. White. “Prehospital Spinal Immobilization And The Backboard Quality Assessment Study.” Prehospital Emergency Care 11.3 (2007): 293-297. Print.
Trajstman, A. C.. “Diagnostic Tests, Sensitivity, Specificity, Efficiency And Prevalence.” Australian Veterinary Journal 55.10 (1979): 501-501. Print.
Trivedi, K., J. Schuur, and D. Cone. “Can Paramedics Read ST-elevation Myocardial Infarction On Out-of-hospital ECGs?.”academic emergency medicine 14.5 Supplement 1 (2007): S159-S160. Print.