Calculation of sample size is one of the important component of design of any research including animal studies. If a researcher select less number of animals it may lead to missing of any significant difference even if it exist in population and if more number of animals selected then it may lead to unnecessary wastage of resources and may lead to ethical issues. In this article, on the basis of review of literature done by us we suggested few methods of sample size calculations for animal studies.

How to calculate sample size in animal studies

This section of the 2010 AHA Guidelines for CPR and ECC addresses cardiac arrest in situations that require special treatments or procedures beyond those provided during basic life support (BLS) and advanced cardiovascular life support (ACLS). We have included 15 specific cardiac arrest situations. The first several sections discuss cardiac arrest associated with internal physiological or metabolic conditions, such as asthma (12.1), anaphylaxis (12.2), pregnancy (12.3), morbid obesity (12.4), pulmonary embolism (PE) (12.5), and electrolyte imbalance (12.6).

The next several sections relate to resuscitation and treatment of cardiac arrest associated with external or environmentally related circumstances, such as ingestion of toxic substances (12.7), trauma (12.8), accidental hypothermia (12.9), avalanche (12.10), drowning (12.11), and electric shock/lightning strikes (12.12).

The last 3 sections review management of cardiac arrest that may occur during special situations affecting the heart, including percutaneous coronary intervention (PCI) (12.13), cardiac tamponade (12.14), and cardiac surgery (12.15).

Asthma is responsible for more than 2 million visits to the emergency department (ED) in the United States each year, with 1 in 4 patients requiring admission to a hospital.1 Annually there are 5,000 to 6,000 asthma-related deaths in the United States, many occurring in the prehospital setting.2 Severe asthma accounts for approximately 2% to 20% of admissions to intensive care units, with up to one third of these patients requiring intubation and mechanical ventilation.3 This section focuses on the evaluation and treatment of patients with near-fatal asthma.

Several consensus groups have developed excellent guidelines for the management of asthma that are available on the World Wide Web: 

### Pathophysiology

The pathophysiology of asthma consists of 3 key abnormalities: 

Complications of severe asthma, such as tension pneumothorax, lobar atelectasis, pneumonia, and pulmonary edema, can contribute to fatalities. Severe asthma exacerbations are commonly associated with …

http://www.kardio.hu/feltoltott/dokumentumok/fajl_201148105352Cardiopulm_resuscit_Pt12_Cardiac_arrest.pdf

Part 12: Cardiac Arrest in Special Situations 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

Sample size estimation in diagnostic test studies of biomedical informatics

Chronic Obstructive Pulmonary Disease (COPD) is a common chronic respiratory disease responsible for significant morbidity and mortality. Population-based health administrative databases provide a powerful and unbiased way of studying COPD in the population, however, their ability to accurately identify patients with this disease must first be confirmed. The objective was to validate population-based health administrative definitions of COPD. Previously abstracted medical records of adults over the age of 35 randomly selected from primary care practices in Ontario, Canada were reviewed by an expert panel to establish if an individual did or did not have a diagnosis of COPD. These reference designations were then linked to each individual's respective health administrative database record and compared with predefine health administrative data definitions of COPD. Concepts of diagnostic test evaluation were used to calculate and compare their test characteristics. The most sensitive health administrative definition of COPD was 1 or more ambulatory claims and/or 1 or more hospitalizations for COPD that yielded a sensitivity of 85.0% (95% confidence interval 77.0 to 91.0) and a specificity of 78.4% (95% confidence interval 73.6 to 82.7). As number of ambulatory claims in the definition increased, sensitivity decreased and specificity increased. Individuals with COPD can be accurately identified in health administrative data, and therefore it may be used to create an unbiased population cohort for surveillance and research. This offers a powerful means of generating evidence to inform strategies that optimize the prevention and management of COPD.

Identifying individuals with physcian diagnosed COPD in health administrative databases.

Diagnostic accuracy of the Berlin questionnaire, STOP-BANG, STOP, and Epworth sleepiness scale in detecting obstructive sleep apnea: A bivariate meta-analysis

Previous evidence suggests different cortical areas naturally oscillate at distinct frequencies, reflecting tuning properties of each region. The concurrent use of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) has been used to perturb cortical regions, resulting in an observed post-stimulation response that is maximal at the natural frequency of that region. However, little is known about the spatial extent of TMS-induced activation differences in cortical regions when comparing resting state (passive) versus active task performance. Here, we employed TMS-EEG to directly perturb three cortical areas in the right hemisphere while measuring the resultant changes in maximal evoked frequency in healthy human subjects during a resting state (N=12) and during an active sensorimotor task (N=12). Our results revealed that the brain engages a higher dominant frequency mode when actively engaged in a task, such that the frequency evoked during a task is consistently higher across cortical regions, regardless of the region stimulated. These findings suggest that a distinct characteristic of active performance versus resting state is a higher state of natural cortical frequencies.

https://emj.bmj.com/content/emermed/20/5/453.full.pdf

An introduction to power and sample size estimation

Objectives: To produce an easily understood and accessible tool for use by researchers in diagnostic studies. Diagnostic studies should have sample size calculations performed, but in practice, they are performed infrequently. This may be due to a reluctance on the part of researchers to use mathematical formulae. 

Methods: Using a spreadsheet, we derived nomograms for calculating the number of patients required to determine the precision of a test's sensitivity or specificity. 

Results: The nomograms could be easily used to determine the sensitivity and specificity of a test. 

Conclusions: In addition to being easy to use, the nomogram allows deduction of a missing parameter (number of patients, confidence intervals, prevalence, or sensitivity/specificity) if the other three are known. The nomogram can also be used retrospectively by the reader of published research as a rough estimating tool for sample size calculations.

https://emj.bmj.com/content/emermed/22/3/180.full.pdf

Simple nomograms to calculate sample size in diagnostic studies

A short cut review was carried out to establish whether a plaster of Paris or functional splint was better for treatment of ulnar collateral ligament rupture. Altogether 50 papers were found using the reported search, of which one presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of this paper are tabulated. A clinical bottom line is stated.

https://emj.bmj.com/content/emermed/19/4/324.1.full.pdf

Plaster or functional splint in gamekeepers thumb

Report by Victor Ameh, Specialist Registrar Checked by Steve Jones, Consultant in Emergency Medicine North Western Deanery and Manchester Royal Infirmary, UK 

A short cut review was carried out to establish whether the internal jugular or the subclavian approach to central venous catheterisation results in fewer complications. A systematic review, published in 2002, addressed this question. No more recent studies were found. The salient features of this review are summarised in table 1. The clinical bottom …

/pdf/best-evidence-topic-report-central-venous-catheterisation-4yxphv12la.pdf

Best evidence topic report. Central venous catheterisation: internal jugular or subclavian approach?

Report by Steve Jones, Clinical Research Fellow Search checked by Magnus Harrison, Clinical Research Fellow 

A patient attends the emergency department with signs and symptoms consistent with a deep venous thrombosis. Somebody suggests that there is a new bedside blood test, called SimpliRed, that may help to rule out the diagnosis in your patient. You know that ruling out a diagnosis is possible by having a …

https://emj.bmj.com/content/emermed/18/2/120.full.pdf

Steve Jones

Papers

An introduction to power and sample size estimation

Simple nomograms to calculate sample size in diagnostic studies

Plaster or functional splint in gamekeepers thumb

Best evidence topic report. Central venous catheterisation: internal jugular or subclavian approach?

SimpliRed and diagnosis of deep venous thrombosis