Author: Claire

Claire Galea is the Owner and Director of Mariposa Holistic Care, through which she provides holistic care services tailored to her clients' personal needs. She is also in her final year following a Degree in Nursing at the Faculty of Health Sciences, University of Malta. Claire is keen about public education on health-related subjects as well as holistic patient-centered care. She is also passionate about spreading positivity and awareness on various subjects through her blog Student Nurse Life.

Statistical Correlation Tests, Bias, Risk & More

Statistical Correlation Tests

Statistical correlation tests are performed with the aim of finding out whether a relationship exists between variables, and then determining the magnitude and action of that relationship. In other words, correlation is a statistical measure that expresses the extent to which two variables are linearly related. It’s commonly used for describing simple relationships without making a statement about cause and effect.

If two variables tend to move up or down together, they are considered to be positively correlated. However, if they tend to move in opposite directions, they are considered to be negatively correlated.

Parametric tests are based on an assumption that the data being analyzed follows a normal distribution. The more data points a distribution has, the more it can approach a normal distribution. Lack of data points would require the use of non-parametric tests.

Non-parametric tests a.k.a. distribution-free tests are methods of statistical analysis that do not require a distribution to meet the required assumptions to be analyzed, especially if the data is not normally distributed.

Student T-Test

statistical correlation tests — Retrieved from https://researchbasics.education.uconn.edu/t-test/ on 11th March 2023

UNPAIRED T-TEST – testing two means

The unpaired t-test a.k.a. independent t-test is a statistical test which aims to determine whether there is a difference between two unrelated groups. The unpaired t-test is used to make a statement about the population based on two independent samples. To make this statement, the mean value of the two samples is compared.

ANOVA – testing more than two means

ANOVA a.k.a. Analysis of Variance, is a statistical test used to investigate the difference between the means of more than two groups. A one-way ANOVA uses one independent variable, whereas a two-way ANOVA uses two independent variables.

CHI-SQUARED TEST – testing the association between two categorical variables

A chi-squared test is a statistical test that is used to compare observed and expected results. The main aim of the chi-squared test is to identify whether a disparity between actual and predicted data is due to chance or to a link between the variables under consideration.

Choosing the Right Test

Bias Potential Sources

Bias is the systematic deviation from the truth. Different sources of bias may include:

selection or sampling bias – inadequate selection of study participants usually due to high non-response rate, inadequate follow-up, inadequate sampling method use, or inadequate controls or comparisons groups
confounding bias – existing differences between comparison groups in one or more parameters which may be directly associated with the outcome and the candidate risk factor in question
instrumental bias – faulty measurement instrumentation due to lack of calibration, inaccurate diagnostic tests, etc
information bias – systematically incorrect measurements or responses, or from differential misclassification of disease or exposure status of participants eg. due to questionnaire ambiguity or insensitivity
systematic bias – one observer may underestimate readings, leading to his respondents having lower readings than those observed by someone else
respondent bias – misunderstandings, lack of interest, or recall issues in the unaffected group
random bias – observer may underestimate or overestimate measurements, which mistakes tend to even out on averaging

Calculating Statistical Risk

In statistics, the risk for a particular group to develop a disease refers to the rate of disease in the group concerned.

RISK DIFFERENCE / ABSOLUTE RISK – the excess risk that exposed individuals have.

RISK RATIO – the measurement of the risk in the exposed group as a multiple of the risk in the unexposed group.

ODDS RATIO – odds refer to the chance of developing the disease rather than not developing the disease. Odds Ratio refers to the chances of developing the condition for an exposed individual relative to an unexposed individual.

The Relevance of Testing the Sensitivity & Specificity of a Screening Diagnostic Test

Screening programs need to provide diagnostic tests with the least disturbance possible for the individual, yet with enough sensitivity and specificity to detect the disease in question. Assessing the sensitivity and specificity of a test requires its outcome to be compared against a gold standard eg. comparing the Faecal Occult Blood Test sensitivity and specificity to a colonoscopy, in this case considered to be the gold standard.

Multi-Variate Analysis

Linear regression analysis is used to predict the value of a variable based on the value of another variable. The variable you want to predict is called the dependent variable, while the variable you are using to predict the other variable’s value is called the independent variable.

Logistic regression is a statistical analysis method to predict a binary outcome eg. yes or no, based on prior observations of a data set. A logistic regression model predicts a dependent data variable by analyzing the relationship between one or more existing independent variables. This technique results in an odds ratio rather than a rate of change per unit change in the independent variable.

Poisson Regression models are best used for modeling events where the outcomes are counts. Or, more specifically, count data: discrete data with non-negative integer values that count something, like the number of times an event occurs during a given time-frame or the number of people in line at the grocery store. This technique results in a risk ratio instead of a rate of change per unit change in the independent variable.

Example of Poisson Regression – Retrieved from https://sherrytowers.com/2018/03/06/poisson-regression/ on 15th March 2023

Survival Analysis is concerned with studying the time between entry to a study and a subsequent event. Originally the analysis was concerned with time from treatment until death, hence the name, but survival analysis is applicable to many areas as well as mortality.

Example of Survival Analysis – Retrieved from https://www.graphpad.com/guides/survival-analysis on 15th March 2023

Relative Survival is defined as the ratio of the proportion of observed survivors in a cohort of cancer patients to the proportion of expected survivors in a comparable set of cancer free individuals. The formulation is based on the assumption of independent competing causes of death.

Example of Relative Survival Analysis – Retrieved from https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0202044 on 15th March 2023

Meta-analysis is a research process used to systematically synthesise or merge the findings of single, independent studies, using statistical methods to calculate an overall or ‘absolute’ effect. Meta-analysis does not simply pool data from smaller studies to achieve a larger sample size.

Example of Meta-Analysis – Retrieved from https://www.mdpi.com/2624-8611/4/4/49 on 15th March 2023

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Statistical Considerations Central Tendency Null Hypothesis & More

Statistical considerations for research should include careful statistical planning and use of the right statistical tests for data analysis to ensure a successful research project.

Central Tendency – Mean, Median & Mode

Central Tendency

The phrase ‘Central Tendency’ refers to a single value which aims to describe a set of data through the identification of the central position within the same set of data. The mean, which at times is referred to as the average, is most commonly considered to be the measure of central tendency, however, there are also the median and the mode which can be considered as measures of central tendency. Which measure is valid depends on the conditions under which they are being evaluated.

medical statistics — Retrieved from https://danielmiessler.com/blog/difference-median-mean/ on 23rd November 2022

The Mean

The mean is the average, where all values are added together and then divided by the number of values.

The Median

The median is the middle value found within the list of values. To find the median you need to list all values in numerical order from smallest to largest, and then identify the value within the middle.

The Mode

The mode is the value occurring most often. This means that if in a particular list of values no number is repeated, there would be no mode for that particular list.

The Variance & Standard Deviation

The variance is a calculation of the normal distribution spread in a set of variables, in other words, a measure of dispersion. The standard deviation is the square root of its variance.

Hypothesis Testing Statistical Considerations

Define the Null Hypothesis – no difference between the groups being compared
Define an Alternative Hypothesis – existing difference between the groups being compared; defined difference should be clinically significant
Calculate a p value – the probability of obtaining the results observed if the null hypothesis is true
Based on the p value, accept or reject the Null Hypothesis
If the Null Hypothesis is rejected, accept the Alternative Hypothesis

NOTE: the size of an expected difference (priori) should be defined prior to the data collection period.

The Null Hypothesis

Studies always start out with the assumption that the difference between the groups being compared will be non-existent a.k.a. null, hence why this is called the Null Hypothesis. Studies aim to have enough evidence to accept or reject this null hypothesis.

Unfortunately, errors may be made in accepting or rejecting the null hypothesis. To prevent such errors, the researcher should aim to have a sample size which is large enough.

The Confidence Interval & P-Value

The phrase confidence interval refers to the range of values which a specific statistic, most commonly being a mean or proportion of the population, can have in the reference population with a specific probability. Confidence intervals help in clinical trial data interpretation by determining upper and lower bounds on the likely size of any true effect.

The p-value determines whether trial results could have occurred by chance.

Confidence intervals are usually preferred to p-values since they provide a range of possible effect sizes in relation to the data, whilst p-values provide a cut-off beyond which we assert that the findings are statistically significant.

A confidence interval which embraces the value of no difference between treatments shows that treatment being investigated is not significantly different from the control.

The cut-off point for rejecting the null hypothesis is arbitrary, a typically being equivalent to 0.05

If p = 0.01, the chance of obtaining the same results as the experiment is 1%, meaning that it is very unlikely, thus we reject the null hypothesis.

If p = 0.7, then the chance of obtaining the same results as the experiment is 70%, thus, we accept the null hypothesis.

NOTE: bias must be assessed before confidence intervals are interpreted, since biased studies can be misleading even when very large samples and very narrow confidence intervals were involved.

(Davies and Crombie, 2003)

Errors & Power Statistical Considerations

Type 1 (Alpha) & Type 2 (Beta) Errors in Statistics

Power statistical considerations

Power is determined by sample size, magnitude of difference sought, and by the arbitrary. For example, a pilot study with a small sample size would have low power. Power desired is usually 0.80

Reference

Davies, H.T.O. & Crombie, I.K. (2003). What are confidence intervals and p-values? What is…? Series. Edition 2009. Hayward Communications Ltd. Hayward Group Ltd. Retrieved from http://www.bandolier.org.uk/painres/download/whatis/What_are_Conf_Inter.pdf on 12th February 2023

Kirkwood, Betty R. (2003). essential medical statistics. Blackwell Science, Inc., 350 Main Street, Malden, Massachusetts 02148–5020, USA: Blackwell. ISBN978-0-86542-871-3.

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Case Control Studies Critical Appraisal

Case Control Studies are typically observational studies commonly used to outline factors related with certain diseases or outcomes. Selection of participants is done on the basis of an experienced outcome. However, to introduce the control aspect within the study, other participants are selected at random from the population without having experienced that outcome. In both the cases and controls participants, exposure is assessed retrospectively through medical records and interviews.

Retrieved from https://www.pinterest.com/pin/408912841140782725/ on 26th February 2023

Hierarchy of Evidence

Case Control Studies Participant Selection Criteria

CASES

clear inclusion/exclusion criteria to ensure homogeneity
cases should ideally be representative of the cases within the target population for external validity purposes
cases should be sourced from the community, clinic, or hospital
accurate diagnosis is important so as not to dilute the cases group with those who do not actually have the disease in question

CONTROLS

controls should be selected from the same population, and may include individuals at risk of developing the outcome
same inclusion/exclusion criteria but without the outcome should be used, with the emphasis being on comparability of cases and controls
accurate classification of controls should be ensured; if confounders are known, they should be matched through a matched study, otherwise, confounders need to be considered in data analysis, and a bigger sample would be required

Matching

Matching is an attempt to ensure comparability between the cases and controls. Matching reduces variability and systematic differences caused by extraneous variables a.k.a. confounders (such as age, gender and race), which may be related to the risk factor.

Bias

INTERVIEWER BIAS – interviewer asks the leading questions, which are different from those used for the control group.

DATA QUALITY – incomplete or inaccurate data

RECALL BIAS – Participants with the disease (CASES) are more likely to recall and report exposure due to having experienced the outcome

Advantages VS Disadvantages

ADVANTAGES	DISADVANTAGES
ideal when seeking possible causes of rare outcomes and outcomes with long latency	may be difficult to select appropriate controls group
does not require a large group of participants	extraneous variables a.k.a. confounder control may be incomplete
relatively quick since the outcome would have already occurred	difficult to validate information
multiple exposures or risk factors can be examined	susceptible to recall bias
relatively inexpensive

Performing Case-Control Studies

cases are identified
control group individuals with similar characteristics but without the outcome in question are identified
exposure is measured retrospectively in both groups
occurrence rate of exposure in cases is compared to the occurrence rate of exposure in control
results are typically obtained through odds ratios or relative risk: show occurrence in exposed is divided by occurrence in non-exposed; if value is 1 = no difference; if value is >1 = risk is higher in exposed; if value is <1 = risk is higher in non=exposed

Cohort Study VS Case Control Study

Retrieved from https://twitter.com/medicine20102/status/682169574859620352 on 26th February 2023

CASP Tool for Case Control Studies

CASP Tool for case-control studies can be accessed here.

To view blogpost featuring Cochrane videos on all types of studies please click here.

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Cohort Studies Critical Appraisal

Cohort Studies are observational studies on groups of people with defined characteristics in which outcomes related to particular exposure (or lack thereof) are compared. Cohort Studies are usually indicated in studies where manipulated exposure is considered to be unethical (eg. no group of people should be asked to smoke for the purpose of outcome comparison). Similarly, these are observational studies, thus they lack the opportunity to control or prevent the expected outcome.

Hierarchy of Evidence

Cohort Studies Advantages & Disadvantages

Cohort Studies need to include a control group – a group which is not exposed to the risk factor of interest. Participants are selected based on their exposure status at the start of the study, and exposed and unexposed groups need to be selected from the same population.

Advantages

exposure to the risk factor of interest is measured prior to disease onset, which reduced bias
rare exposures can be examined by appropriate selection of study cohorts
multiple outcomes can be studied for a single type of exposure
calculates incidence and relative risk of disease in both exposed and unexposed participants over time

Disadvantages

changes in the participants’ exposure status and diagnostic criteria that may happen over time can affect the individuals’ classification based on exposure and disease status; the researcher should think about what measures may need to be taken if the participants change their patterns throughout the study period
risk of information bias – outcome may be influenced by information on the participant’s exposure status
loss of follow-ups may introduce attrition bias, where the characteristics of drop-outs and those completing the study may be significantly different, leading to a reduction in the validity of the study
expensive and time consuming

Preventing Loss to Follow Up

During the recruitment process, the researcher should obtain all information required so that the participant can be easily contacted. In addition, the researcher should exclude participants that are likely to be lost (eg. a prospective participant may have plans to move to another country).

During the follow-up period, the researcher should maintain regular contact through different means, and possibly provide tokens or gifts to encourage continued participation.

Prospective VS Retrospective Cohort Studies

In Prospective Cohort Studies, participants are identified at the time of exposure. They are followed up over time until outcome occurs.

Advantages: Prospective Cohort Studies are designed with specific data collection methods.

Disadvantages: Such studies entail a long indefinite follow-up period until an outcome occurs. They are susceptible to loss of follow-up, and are usually expensive.

In Retrospective Cohort Studies, the chosen participants would have already been exposed to and subsequently experienced an outcome. Thus, outcome data measured in the past is then reconstructed for analysis.

Advantages: Retrospective Cohort Studies are cheaper and quicker than prospective studies, and make use of past data, which can be accessed immediately.

Disadvantages: Such studies are susceptible to both recall bias and information bias, and may be subjected to incomplete, inaccurate, or inconsistent data due to limited control over data collection.

Cohort Studies Critical Appraisal

Casp Tool

CASP Tool for Cohort Studies Critical Appraisal can be found here.

To view blogpost featuring Cochrane videos on all types of studies please click here.

Types of Statistical Tests Used in Cohort Studies

Risk Ratio (RR)
Odds Ratio (OR)
Confidence Interval (CI)

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Systematic Reviews and Meta Analysis Critical Appraisal

A systematic review is a summary of clinical literature which, through explicit reproducible methods, performs a comprehensive and systematic literature search and critical appraisal of individual studies. Systematic reviews may incorporate statistical techniques with which they combine valid and similarly designed studies together to produce an average estimate of effect based on all reviewed studies – this is what we refer to as a meta-analysis.

Hierarchy of Evidence

How To Perform Systematic Reviews & Meta Analysis

Step 1 – develop a question
Step 2 – define the criteria for inclusion of studies
Step 3 – perform a systematic search through available literature to find eligible studies (fitting all PICO elements)
Step 4 – review methods and results of the selected studies
Step 5 – assess heterogeneity (variation) between studies
Step 6 – apply statistical methods to produce a summary result

Critically Appraising a Review

check whether the author/s specified their clinical query
check whether each key element of the question (PICO) is clear and specific
scrutinise the search strategy that was used – were boolean operators used? Was the author/s’ search extensive and comprehensive enough? If not, the study should be revised and retested. The search should include a good keyword combination, good databases, grey literature (so as to prevent publication bias), limiters, and more than one person in the search (prevents bias – sometimes it’s difficult to assess whether or not a study should be used or not, hence 2 or more should be included in this process (if consensus is not met)
check whether the author/s applied any quality criteria in study selection

Publication Bias

In order to avoid publication bias, authors of reviews should look into books, grey literature, and unpublished material eg. conference proceedings, dissertations etc. This is because one should keep in mind that positive and statistically significant results are more likely to be published and be included in scientific journals easily found in electronic databases.

Critically Appraising a Meta Analysis

Heterogeneity testing

test for clinical and statistical heterogeneity
use various tests such as chi square test, and give p value. If p value is large, difference between results is not significant

statistical calculations

use fixed or random effect models
random effect models are used to make up for heterogeneity, usually needing a large sample but providing conservative results
NEED to qualitatively examine the potential cause of heterogeneity prior to deciding to pool results

sensitivity analysis

check on the impact of low quality papers on the overall result
1st analysis requires the exclusion of dubious studies
2nd analysis requires the re-inclusion of dubious studies to see if they affect the overall result

PRISMA Diagram

When researchers choose to perform a systematic review, they are required to present the whole search process within a PRISMA diagram. Any grey literature or manually retrieved literature should also be included in the PRISMA diagram (sample PRISMA flow diagram can be found below…)

PRISMA Flow Diagram – Retrieved from https://esraeurope.org/prospect/procedures/oncological-breast-surgery-2019/evidence-review-process-9/prisma-flow-diagram/ on 22nd February 2023

PRISMA, a.k.a. Preferred Reporting Items for Systematic Reviews and Meta-Analyses, is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses (sample PRISMA checklist can be found below…)

CASP Tool for Systematic Reviews

CASP tool for systematic reviews can be found here.

To view blogpost featuring Cochrane videos on all types of studies please click here.

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Randomised Controlled Trials Critical Appraisal of RCTs

Randomised Controlled Trials are quantitative experimental studies in which individuals are allocated to receive one of multiple clinical interventions or a control at random. Interventions that individuals may be subjected to in Randomised Controlled Trials include treatment (or placebo), prevention strategies, screening programs, diagnostic tests, different settings, or educational models.

RCTs are excellent at providing answers to questions seeking the effectiveness of different interventions.

Hierarchy of evidence

Characteristics of Randomised Controlled Trials

include one (or more) treatment arm and a control arm
participants are allocated at random to one of the groups
both the participants and the researchers remain unaware of which intervention was allocated to the groups
each group is treated identically (except the intervention being investigated)
participants are analysed within their assigned group, irrespective of the allocated intervention
analysis aims to estimate the size of the difference in predefined outcomes between the groups

What Makes RCTs Superior To Other Research Methods?

In RCTs, which are experimental studies, exposure is controlled by the researcher. On the other hand, in cohort and case control studies, which are observational studies, the researcher follows the outcomes related to exposures over which they had no control.

Whilst other study designs can point out associations between an intervention and an outcome, they are not able to exclude the effect of an extraneous factor linked to both.

Randomised Controlled Trials ~ Parallel Design vs Crossover Design

There are 2 types of RCTs:

Parallel Design: in this type of RCT, each group of participants is exposed to one of the interventions only; intervention assigned to each group is determined at random
Crossover Design: in this type of RCT, each participant is subjected to all the interventions within the study in successive periods; first intervention allocated is determined at random

Blinding – Single vs Double

In the ideal RCT, both the participants and the clinicians are left unaware of which participants are receiving which intervention. This is what we refer to as blinding. Blinding reduces the risk of ascertainment bias (when some members of the target population are more likely to be included in the sample than others) and observation bias (when a researcher’s expectations, opinions, or prejudices influence what they perceive or record in a study). An RCT without any type of blinding is referred to as an open trial.

Retrieved from http://regulatoryworld.blogspot.com/2014/08/clinical-trials-at-glance-part-1_31.html on 18th February 2023

Ethical Considerations

Prior to the start of a Randomised Controlled Trial, there needs to be genuine doubt on whether one intervention is superior to another, as well as a balance between any potential risks to the participants and potential benefits to future patients.

Thus, one needs to keep in mind that it is unethical to expose participants to a presumably inferior or potentially harmful intervention. It is also unethical to deprive patients from an intervention which is presumed to be beneficial.

RCTs Limitations

recruitment difficulties
blinding difficulties
costly and time consuming
requires large sample size to detect small intervention effects
not ideal for screening or interventions with rare outcomes or outcomes emerging after long intervals
randomisation may not be possible due to patient preferences or clinicians’ decisions

Critically Appraising Randomised Controlled Trials

critical appraisal of randomised controlled trials depend on reporting accuracy
results tend to emphasise statistical significance instead of clinical importance
small sample size leads to insufficient ability in detecting significant differences
poor randomisation reporting
poor blinding
no follow up

CASP TOOL for RCT

CASP Tool for critically appraising Randomised Controlled Trials can be found here.

To view blogpost featuring Cochrane videos on all types of studies please click here.

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Critical Appraisal of a Research Study

What are the key concepts of critical appraisal? This blogpost features a very good series of critical appraisal training videos published by Cochrane Mental Health on Youtube (full credits can be found at the bottom of this blogpost).

Hierarchy of Evidence

Critical Appraisal Introduction

In this first video, the key concepts of critical appraisal are introduced, and the learning objectives for the series are clearly defined.

Systematic Reviews and Meta Analysis

In this second video, we are introduced to the fundamentals of systematic reviews and the ways in which we can apply the critical appraisal concepts of validity, trustworthiness of results, and value and relevance using the CASP checklist. The full text version of the study by Hay et al (2019) mentioned in this video can be found here.

Randomised Controlled Trials

In this third video, we are introduced to the fundamentals of randomised controlled trials and the ways in which we can apply the critical appraisal concepts of validity, trustworthiness of results, and value and relevance using the CASP checklist. The full text version of the study by Sugg et al (2018) mentioned in this video can be found here.

Cohort Studies Critical Appraisal

In this fourth video, we are introduced to the fundamentals of cohort studies and the ways in which we can apply the critical appraisal concepts of validity, trustworthiness of results, and value and relevance using the CASP checklist. The full text version of the study by Gerhard et al (2015) can be found here.

Case Control Studies

In this fifth video, we are introduced to the fundamentals of case control studies and the ways in which we can apply the critical appraisal concepts of validity, trustworthiness of results, and value and relevance using the CASP checklist. The full text version of the study by Drucker et al (2018) can be found here.

Cross Sectional Studies

In this sixth video, we are introduced to the fundamentals of cross-sectional control studies and the ways in which we can apply the critical appraisal concepts of validity, trustworthiness of results, and value and relevance. The full text version of the study by Boden et al (2010) can be found here.

Diagnostic Studies Critical Appraisal

In this seventh and last video, we are introduced to the fundamentals of diagnostic studies and the ways in which we can apply the critical appraisal concepts of validity, trustworthiness of results, and value and relevance using the CASP checklist. The full text version of the study by Hollis et al (2018) can be found here.

Reference

The above embedded videos are part of a project which was developed to enhance research use and development across two NHS Trusts.

The project founding partners were:

Cochrane Common Mental Disorders
Northumberland, Tyne and Wear NHS Foundation Trust (NTW), UK
Tees, Esk and Wear Valleys NHS Foundation Trust (TEWV), UK

Delivery of the project was supported by the Centre for Reviews and Dissemination at the University of York.

Funding Acknowledgement: The production of the critical appraisal modules was jointly funded by:

Economic and Social Research Council (ESRC), UK – as part of the University of York ESRC Impact Acceleration Account (ES/M500574/1)
Northumberland, Tyne and Wear NHS Foundation Trust (NTW), UK
Tees, Esk and Wear Valleys NHS Foundation Trust (TEWV), UK
University of York, UK

Cochrane Review Group Funding Acknowledgement: The National Institute for Health Research (NIHR) is the largest single funder of the Cochrane Common Mental Disorders Group.

Disclaimer: the views and opinions expressed herein are those of the module authors and do not necessarily reflect those of the ESRC, NIHR, the National Health Service (NHS), the Department of Health and Social Care or the University of York.

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Infection Prevention and Control in the Critical Care Setting

Patients in the critical care setting are more susceptible to Health Care Associated Infections (HCAIs), making infection prevention and control even more crucial within this setting. Some of the most common infection manifestations in the critically ill patient include pneumonia following intubation, bloodstream infections following IV catheterisation, and UTIs following urinary catheterisation.

Susceptibility to HCAIs within the critically ill population can be due to:

altered immunity – due to steroid use, surgery, anaesthesia and age
invasive lines – provide direct entry of bacteria into the patient’s bloodstream
underlying illnesses or conditions
broad spectrum antibiotics
mechanical ventilation

These risks cause an increased morbidity and mortality rate, a longer hospitalisation stay, and subsequently, higher treatment costs.

Antibiotic Use

We are currently witnessing a dramatic increase in infections by multi-drug resistant pathogens, leading to difficult infection management due to the scarcity of available antibiotics. Even more so, within the critical care setting there is an increased risk of patient-to-patient transmission, increased antibiotic use, and critically sick patients.

Multi Drug Resistant organisms (MDRO)

GRAM POSITIVES

VRE – Vancomycin-resistant Enterococci
MRSA – Methicillin-resistant Staphylococcus aureus

GRAM NEGATIVES

CRE – Carbapenem-resistant Enterobacterales
Pseudomonas aeruginosa CRE
ESBL-positive bacteria

OTHERS

Clostridium difficile
Neisseria meningitidis
Mycobacteria tuberculosis

Retrieved from https://slideplayer.com/slide/13193459/ on 28th January 2023

Infection Prevention and Control in the ICU Setting

General Preventive Techniques

follow the 5 moments of hand hygiene
alcohol hand rub should be the first hand hygiene choice – unless hands are visibly soiled
nails should be kept well trimmed with no gels
reduce jewellery use to just one plain wedding band if necessary
keep patients with MDRO in isolation rooms if possible
allocate equipment to one patient without sharing
screen patients for MDRO, specifically for MRSA, CRE and VRE on admission and at least weekly thereon
promote awareness on ANTT (aseptic non-touch technique) amongst colleagues
ensure disinfection of shared equipment such as monitoring lines, saturation probes, ECG leads, and blood pressure cuffs
promote education on infection prevention and control for staff and cleaners
educate patients’ relatives on infection prevention and control measures
ensure appropriate antibiotic use
ensure terminal cleaning of bed area upon patient discharge

infection prevention and control — Retrieved from https://surewash.com/news/moments-hand-hygiene/ on 28th January 2023

Glove Use

change gloves between procedures on the same patient when performing dirty vs aseptic tasks
change gloves between patients
don gloves immediately before contact with patient body fluid, mucous membranes, or non-intact skin
remove and discard immediately after a procedure and perform hand hygiene so that contamination is not transferred to another patient

Rectal screening for CRE and VRE

insert a charcoal swab approximately 2cn inside the rectum and rotate gently
ensure swab is brown-stained with faeces to ensure a good sample has been taken, as inadequate samples are not processed by the lab

Bathing Patients in Critical Care Setting

as previously mentioned, there is a high prevalence of MDROs in the critical care setting
daily chlorhexidine bathing of patients in the critical care setting is encouraged since chlorhexidine helps reduce the risk of acquiring MDROs
washing the patient’s body with chlorhexidine has been showing effectiveness in the prevention of carriage and possibly bloodstream infections with Gram-positive MDROs (MRSA and VRE)
chlorhexidine washes have shown possible eradication of carriage and infection prevention of Gram-negative MDROs, however, more evidence is required in this regard

Disinfecting Isolation Rooms

isolation rooms should be disinfected on a daily basis
isolation rooms should be cleaned last using yellow cloths, disposable gloves, and chlorine-based disinfectant
terminal cleaning and disinfection of isolation rooms should be done following patient discharge; all surfaces need to be cleaned with detergent; mattresses and pillows should be cleaned with environmental disinfectant wipes; UV-C disinfection should be performed, by which more than 99.9% of C. difficile spores and MRSA are killed in minutes

ADVANTAGES OF USING CHLORINE-BASED DISINFECTANT:

inexpensive
low toxicity
rapid effect
broad spectrum disinfectant – bacteriocidal, tuberculocidal, fungicidal, virucidal

DISADVANTAGES OF USING CHLORINE-BASED DISINFECTANT:

corrosive
long contact time
employee complaints

The Nurse’s Role in Proper Antibiotic Management

knowledge on antibiotic resistance
knowledge on the most frequently used antibiotics within the critical care setting
knowledge on the disadvantages of using broad spectrum antibiotics – prolonged use increases risk of C. difficile
administer antibiotics at the recommended dosage intervals for optimal effectiveness
- administer IV antibiotics safely and effectively, with diligence to dosage, dilution, timing and calculations
administer IV antibiotics to patients with sepsis within 1 hour following diagnosis to increase risk of survival
list reminders for antibiotic review eg. stop date, reason for prescription, change of route, etc
therapeutic monitoring of antibiotic levels eg. Gentamicin, Amikacin and Vancomycin require serum blood level checking for safe and effective treatment; ensure samples are taken at the appropriate time for best results
understand when to withold an antibiotic dose until results are available eg. in the case of Gentamicin
serum blood level samplings should be properly documented in both the patient’s notes and on the lab request form
proper handover on transfer from ICU to another ward

Ventilator Associated Pneumonia (VAP)

Pneumonia is an infection in the lung parenchyma, particularly in the bronchioles and alveoli, which is caused by pathogens such as bacteria, fungi and viruses.

Ventilated Associated Pneumonia (VAP) is pneumonia which develops 48 hours following intubation and initiation of mechanical ventilation. VAP is considered to be the 2nd most common HCAIs but the most serious one, with 25% of these patients with VAP ending up dead.

VAP happens because intubation bypasses all natural defense mechanisms within the tracheo-bronchial tree that protect the lower respiratory tract from infections.

Causative organisms, some of which are often present in the oropharyngeal cavity and the gastrointestinal system, are:

Gram-negative aerobes – Pseudonomas aeruginosa, Klebsiella pneumonia, Acinetobacter, Enterobacter
Gram-positive aerobes – Staphylococcus aureus/MRSA

There are 5 defense mechanisms which are bypassed during ventilation:

The Larynx and the Glottis – prevent aspiration of oral content
The Coughing Reflex – helps in the expelling of secretions and aspirated matter from the larger airways
Mucous – helps trap small particles
Cilia – hair-like structures which help move mucous up from the lower respiratory tract towards the larynx to be expelled
Phagocytic Cells – engulf bacteria if or when they manage to reach the alveoli

Aspiration of contaminated fluids and secretions into the lungs can happen in various ways:

colonisation of pathogenic bacteria within the oropharynx or tracheo-bronchial tree
the stomach, through enteral feeding, certain drugs (eg. stress ulcer prophylaxis), and supine patient positioning, may act as a source of pathogens for VAP
inhalation of aerosols through contaminated intubation or nebulisation equipment

Pathological development of pneumonia

aspiration of contaminated fluids or secretions into the lungs
initiation of the inflammatory response
swelling of the mucous membranes of the alveoli and bronchi
pus collects within the alveoli
interference of pus with the gas exchange process
development of pneumonia

Signs & Symptoms of VAP Pneumonia

temperature of >38°C
tachypnoea and/or dyspnoea
purulent sputum (off-white, yellow or green, and opaque)
worsening ABGs – poor SaO2 and increased ventilatory demands
positive sputum and/or blood cultures
leukocytosis >12,000 WBC/mm²
chest x-ray or CT scan with evidence of pneumonia

NOTE: Diagnosing VAP can be difficult!

VAP Risk Factors

length of time in which the patient is exposed to the healthcare environment
predisposing host-related factors such as age, malnutrition etc
treatment factors eg. endotracheal intubation, prolonged exposure to antibiotics

VAP Consequences

increased mortality
prolonged mechanical ventilation
increased antibiotic use
prolonged stay at the ITU and hospital
increased medical cost

VAP Infection Prevention and Control

do not intubate patient unless necessary
choose non-invasive ventilation over invasive ventilation where possible
elevate head of bed 30-45° especially for patients receiving enteral feeding
minimise aspiration of contaminated oropharyngeal and tracheal secretions
suction subglottic secretions
avoid gastric over distention
avoid unplanned extubation
maintain correct ETT cuff pressure (20cm H2O)
provide frequent oral hygiene – suctioning, toothbrushing, and using chlorhexidine mouthwashes
use HME filters rather than heated humidifiers
remove condensate from ventilatory circuits periodically
extubate as soon as possible

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Neonatal & Paediatric Intensive Care Nursing

One of the most common measures required in neonatal and paediatric intensive care nursing is respiratory support. Such assistance for the neonate or paediatric patient may include the use of nasal prongs, high flow nasal cannulae, non-invasive ventilation, or invasive ventilation. Invasive ventilation should be left as a last resort in babies.

Respiratory Support Devices

BAG & MASK VENTILATION

neonatal and paediatric intensive care nursing — Retrieved from https://litfl.com/bag-valve-mask-bvm-ventilation/ on 27th January 2023

NEOPUFF

NASAL PRONGS

OPTIFLOW

Non-Invasive Ventilation

Non-invasive ventilation (NIV) is a well recognised and increasingly prevalent intervention in the paediatric critical care setting. In the acute setting NIV is used to provide respiratory support in a flexible manner that avoids a requirement for endotracheal intubation or tracheostomy, with the aim of avoiding the complications of invasive ventilation.
Morley, 2016.

EasyFlow nCPAP Non-Invasive Ventilation

CPAP non-invasive ventilation leaves extra air in the lungs to keep the lungs slightly inflated; this minimises the effort required for the progressive breath.

Complications of Non-invasive Ventilation

Nasal Septum Injury –
Nasal Bridge Injury –
Eye Puffiness & Hyperemia –
Abdominal Distention –
Pneumothorax –

Nasal Septum – retrieved from https://www.drugs.com/health-guide/deviated-septum.html; Nasal Bridge – retrieved from https://www.mountsinai.org/health-library/symptoms/low-nasal-bridge; Abdominal Distention – retrieved from https://adc.bmj.com/content/97/Suppl_2/A160.4.short on 27th January 2023

Ventilation

Ventilation is used as a last resort on babies.

CHILD VS ADULT AIRWAY

Unlike the adult’s airway, a baby’s airway is funnel-like, and the cricoid sits lower than in adults.

PAEDIATRIC LARYNGOSCOPY

The type of laryngoscope commonly used in case of ventilation of paediatric patients is the Miller Blade Laryngoscope with Fibre Optic.

CUFFED VS UNCUFFED ETT

we are moving towards commonly using the inflated microcuff ETT for paediatric patients, since it helps minimise the risk of aspiration
an inflated microcuff seals the trachea so as to prevent positive pressure from escaping the lower airway
an inflated microcuff also seals the upper airway so that material above the glottis cannot enter the trachea

Intubation Drugs

Babies that are intubated right after birth are NOT administered any intubation drugs during the procedure. Otherwise, babies being intubated later on are administered drugs from the following intubation drugs list:

RAPID SEQUENCE INTUBATION DRUGS (RSI)

Fentanyl – analgesic opioid
Atropine – treats symptomatic bradycardia
Suxamethonium – muscle relaxant

MAINTENANCE DRUGS

Morphine – analgesic opioid
Midazolam – benzodiazepine
Atracurium – muscle relaxant

DOSAGE CALCULATION

Rapid Sequence Intubation Drugs and Maintenance Drugs dosages are administered based on the baby’s weight according to protocol.

For antibiotic and other pharmacological drug use:

mg of drug required X volume of fluid drug is in

____________________________

mg of drug in the volume you have

NOTE: many drugs need to be administered slowly by IV infusion over half an hour.

Neonatal and Paediatric Intensive Care Nursing

WetFlag Acronym Table

Procedural Pain Relief

Measures related to the baby’s surrounding environment, preparation, and use of non-pharmacological pain relief methods can be taken for support:

warmed area
calm surrounding
parental presence
reduction of light, noise, and handling
available staff to reduce interruptions and prepare requirements beforehand
available staff to assume a parental role if parents are unavailable
promote swaddling, nesting, tucking, holding, cuddling, skin-to-skin care, breast feeding, non-nutritive sucking, clean nappy, and distraction techniques.

24% sucrose solution ampoules (Babycalmine S) can be administered as a mild analgesic for short term pain and distress in neonates and infants up to 4 months of age during minor procedures, such as bloodletting and cannulation, invasive procedures including urinary catheterisation and lumbar puncture, as well as during IM or SC immunisation and other procedures which may require pain relief.

Retrieved from https://deltamedint.com/sucrose-solution-reduces-pain-and-cost/ on 27th January 2023

comprehensive assessment

Comprehensive assessment in neonatal and paediatric intensive care nursing needs to be based on observing and reading clinical signs, as well as interpreting different parameters:

heart rate
blood pressure
signs of distress
abdominal distention
pressure exerted by lines
cannula observation
signs of sepsis
functioning equipment observation

NOTE: a low temperature in a baby may be a sign of sepsis; capillary refill on a newborn is checked on the sternum.

The Nurse’s Role

INFANTS:

prompt treatment may be required by premature babies suffering from respiratory difficulties
nutritional needs of premature babies and sick neonates are calculated on the baby’s weight in kg
encourage parents to stay with their infant
provide the baby with opportunities for sucking
provide toys to provide comfort and stimulate interest
provide pharmacological and non-pharmacological pain control

TODDLERS:

encourage independent behaviours eg. self-feeding, hygiene, dressing
encourage continuation of toilet-training regime, accepting regression during hospitalisation
provide vigilance and safety within the toddler’s environment
provide short and simple explanations
reward appropriate behaviour

PARENTS:

support the parents, considering their possible anxiety and stress
encourage an active role in the care of their own child
teach parents to administer medications safely, to use any necessary equipment, to insert and/or use a feeding tube if needed
discuss with parents subjects related to home routine, safety, and how to coax a reluctant baby to feed
teach parents Basic Life Support
provide reassurance during discharge planning, since this transition may be quite difficult and scary for the parents

The Parents’ Role

Parents of young patients staying at NPICU are usually allowed to enter, excluding time in which ward rounds, handover, emergencies and admissions are being performed. The NPICU promotes:

family centered care
parents’ empowerment to prevent loss of parental role
interventions such as skin-to-skin contact and positive touch

Reference

Morley S. L. (2016). Non-invasive ventilation in paediatric critical care. Paediatric respiratory reviews, 20, 24–31. https://doi.org/10.1016/j.prrv.2016.03.001

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NPICU – Neonate and Paediatric Monitoring & Central Lines

The first 28 days of life are the most crucial for survival. While on a global scale neonatal mortality is declining, 54% of the total deaths amongst Europe’s children under 5 occur in neonates. This sheds a light on the importance of adequate monitoring and care at the NPICU neonatal and paediatric intensive care unit.

Local causes of mortality in children under 5 years of age include:

prematurity
congenital anomalies
non-communicable diseases (eg. heart disease, cancer, chronic respiratory disease, and diabetes)
birth asphyxia (failure to establish breathing at birth) and trauma
acute lower respiratory infections
sepsis
meningitis

The NPICU – Neonatal & Paediatric Intensive Care Unit

Malta’s only NPICU caters for limitless admissions of neonates and children up to 3 years of age, with the majority of these young patients being premature babies (babies born before the 37th week of gestation) and neonates (from birth to 28 days of age).

Classification of care in the NPICU is as follows:

Intensive Care – 1 or 2:1 care ratio
High Dependency Care – 1:1 care ratio
Special Care – 1:2 care ratio
Nursery – 1:4 care ratio

Apart from being allocated according to experience and training needs, NPICU nurses may need to act as transport team members, Basic Life Support educators, and link nurses.

Why Do Neonates Require Intensive Care?

Maternal Factors

premature membranes rupture
multiple pregnancy
hypertension
diabetes
drug or alcohol exposure
sepsis
bleeding
too much or too little amniotic fluid

Delivery Factors

foetal distress
birth asphyxia
breech delivery
meconium
nuchal cord (umbilical cord wrapped around baby’s neck)
ventouse (vacuum cup) / KIWI (most common type of ventouse that does not use a suction machine)
cesarean

Baby factors

CHANGES AT BIRTH:

independent breathing
foetal to neonatal circulation
metabolic adaptation to thermoregulation, glucose homeostasis, and fluid balance

POST-NATAL CHANGES:

baby’s lungs become the primary respiratory organs
lungs’ blood vessels respond to oxygen increase from vasodilation, promoting blood flow to the lungs
increase in oxygen causes heart ducts to close, leading to neonatal circulation to establish itself

NORMAL CHANGES:

during the baby’s first breaths, air replaces the fluid within the lung

THERMOREGULATORY CHANGES:

at birth, intrauterine heat reservoir and heat exchange through the placenta is lost
following birth, thermal stability is normally achieved independently, as they adapt to the new environment by the non-shivering thermogenesis process
the newborn baby should be kept warm and dry straight from delivery, since becoming cold causes the brown fat stores to become depleted, leading to neonatal hypoxia and hypoglycaemia

GLUCOSE HOMEOSTASIS CHANGES:

at birth, the baby stops obtaining glucose from the mother through the placenta, and starts to produce glucose independently, which, following birth, may cause a decrease in the baby’s blood glucose levels
normally, if kept warm and is fed appropriately within the first few hours after birth, a full term baby is able to control his/her own blood glucose levels within normal limits

FLUID BALANCE CHANGES:

at birth, fluid balance undergoes significant adaptive changes, including extra-cellular fluid contraction following delivery, where neonates may lose up to 10% of their total birth weight

Premature vs Full Term Babies

Premature babies commonly experience respiratory issues, including:

respiratory distress syndrome (due to surfactant deficiency)
chronic lung disease of prematurity (caused by oxygen dependency and persistent inflammatory changes of the lungs past 28 days following birth)
apnoea of prematurity (due to immature brain stem)

NPICU Admission Guidelines

23 weeks-35 weeks or more than 42 weeks gestation
birth weight of 450g – 2kgs, SGA (small for gestational age) and LGA (large for gestational age)
respiratory issues – apnoea, cyanotic episodes, need for positive pressure ventilation, concerning respiratory distress, tachypnoea for over 1hr, perinatal asphyxia, and meconium aspiration
gastrointestinal issues – feeding problems, bile-stained vomiting, signs of obstruction
infection – sepsis suspicion, herpes, chlamydia, group B streptococcus
malformations
congenital heart defects
infants of mothers with diabetes
hypoglycaemia
seizures
surgical complications
neonatal abstinence syndrome – conditions caused when a baby withdraws from certain drugs he’s been exposed to in the womb prior to birth
hyperbilirubinaemia – higher-than-normal amount of bilirubin in the blood, causing jaundice
monitoring

Monitoring

CONTINUOUS MONITORING of:

heart rate
respiratory rate
arterial blood pressure
pulse oximetry
capnography
cerebral function monitoring

INTERMITTENT MONITORING of:

blood gases
serum bilirubin
blood glucose
others as needed eg. haemoglobin, electrolytes, etc.

Central Lines

CVCs (central venous cannulas) can be used for longer than PVCs (peripheral venous cannulas). IV treatments as well as higher concentration IV fluids and TPN can be administered via a CVC with less irritation and damage to the veins.

UMBILICAL CATHETERS

A umbilical cord typically has 2 arteries and 1 vein. Catheters are placed into the blood vessel using sterile technique, followed by a confirmation x-ray to determine position.

An umbilical arterial catheter is used for:

blood sampling
ABGs
invasive blood pressure monitoring
DO NOT ADMINISTER IV FLUIDS IN AN ARTERIAL CATHETER!

An umbilical venous catheter is used for:

IV fluid administration
IV treatment
exchange transfusion
emergency access during resuscitation

Retrieved from https://clipart.me/free-vector/umbilical-cord on 26th January 2023

PICC LINE

A PICC line – Peripherally Inserted Central Catheter – is a thread-like tube which is inserted in a small vein and threaded into a larger vein leading to the Superior Vena Cava.

when handling the baby, the nurse should be extra careful as to not pull the catheter
infusion lines should be carefully changed on alternate days using a sterile technique

NOTE: Neonatal PICC lines SHOULD NOT be used for blood sampling!

TUNNELED LINES

a tunneled catheter is a catheter inserted under the skin, exiting on the chest a.k.a. Hickman
the line is anchored in place by the Dacron cuff, helping to prevent infection

NON-TUNNELED LINES

femoral line
jugular
subclavian
brachiocephalic

INTRA-OSSEOUS LINES

TIVAD – TOTALLY IMPLANTED VENOUS ACCESS DEVICE

Totally Implanted Venous Access Devices are only used in older children
accessed and de-assessed by a certified nurse with a special needle – once needle is in place, it can be used like any other central line

PERIPHERAL ARTERIAL LINES

used for frequent blood sampling
provide accurate invasive blood pressure monitoring
high risk

Retrieved from https://emedicine.medscape.com/article/1999586-technique on 26th January 2023

CENTRAL LINE MONITORING

Central line monitoring is very important since signs and symptoms may be indicating line blockages, vein irritation, thrombus, migration, and CLABSI (central line-associated bloodstream infection). Signs and symptoms that the nurse should watch out for include:

extremity discolouration
bleeding
swelling
extravasation
dislodgement
signs of sepsis

Infiltration – Retrieved from https://europepmc.org/article/pmc/6082416#free-full-text on 26th January 2023

Extravasation – Retrieved from http://www.worldwidewounds.com/1997/october/Neonates/NeonatePaper.html on 26th January 2023

Ischaemia & Necrosis following Peripheral Arterial Cannulation – Retrieved from https://www.semanticscholar.org/paper/Analysis-of-characteristics-of-peripheral-arterial-Kim-Lee/973dec4ffd825f9c336134d16004935b15a83921 on 26th January 2023

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