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Blood gas analysis is not reliable for serum electrolytes and can lead to wrong clinical decisions

To the editor:

We’ve read the recent research paper of Karataş et al. which reported high correlation between blood gas analyzer (BGA) and laboratory autoanalyzer (LAA) measurements of electrolytes, hemoglobin and glucose and concluded that they could be used interchangeably in clinical situations, but we think that there is a deficiency in the statistical method of this study and the conclusion made accordingly is also incorrect [1].

When we accept one of the two laboratory test methods as a reference and want to evaluate the usability of the other method instead of the reference test, it is not enough to simply look at the correlation between the results of the two measurement methods. Although the correlation coefficient is very high, it cannot be concluded that the test results are compatible with each other. As an example, let’s take a dataset and suppose that the K+ value measured in LAA is 1.5 times higher than the K+ value measured in BGA in each case. In such a situation, a perfect correlation between measurement methods will be detected (the Pearson correlation coefficient = 1, p <0,001). However, when we look at this dataset, we can evaluate a patient who is hypokalemic with 2,4 mmol/L according to the LAA result as normokalemic with 3,6 mmol/L according to the BGA result. If we look at the same dataset again, we accidentally begin the treatment of hyperkalemia in a patient whose K+ value is measured as 4 mmol/L in LAA, which is within normal limits, if we rely on the results of BGA which will reveal K+ value as 6 mmol/L. As can be seen from this example, when evaluating the reliability of the two test measurement results, it is wrong to make conclusions only by looking at the correlation coefficient. In this case, the test that should be preferred is the Bland-Altman analysis, and a compatibility assessment should be made along with the correlation [2].

In our study, which presented the highest number of cases related to BGA and LAA compatibility in the literature, 31060 patient data were examined and although moderate correlation was found for sodium and potassium, and strong correlation was found for hemoglobin, hematocrit and glucose, mean differences were not within acceptable limits for any test. Therefore, it has been concluded that blood gas analysis is not a completely reliable method, it is more appropriate to wait for biochemistry results instead of making early clinical decisions with blood gas analysis especially when the results and the patient’s clinic is not compatible, and blood gas analysis can be used carefully as a decision-making tool only in patients who are hemodynamically unstable and when the test result is compatible with the patient’s clinic [3].

As a result, we think that Karataş et al. made an erroneous conclusion due to statistical deficiency, and it was healthier to interpret the results of the study by making the Bland-Altman analysis.


1. Karatas A, Canakci E. Can the clinician trust blood gas for serum electrolyte levels? J Clin Anal Med. 2019;10(2): 151-5.

2. Doğan NÖ. Bland-Altman analysis: A paradigm to understand correlation and agreement. Turk J Emerg Med. 2018;18(4):139–41.

3. Altunok İ, Aksel G, Eroğlu SE. Correlation between sodium, potassium, hemoglobin, hematocrit, and glucose values as measured by a laboratory autoanalyzer and a blood gas analyzer. Am J Emerg Med. 2019;37(6):1048-53.

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COVID-19: Current information and anesthesia

To the editor:

The recent outbreak of respiratory illness, first detected in Wuhan City, Hubei Province, China, is caused by a newly detected coronavirus named “2019-nCoV. In this article, the features of prevention, diagnosis, and treatment methods are explained with the literature [1-4].

Coronaviruses (CoV) are a family of viruses that cause illness ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS-CoV). Coronaviruses are enveloped RNA viruses with a single chain and positive polarity. They do not contain RNA-dependent RNA polymerase enzymes because they have positive polarity, but they encode this enzyme in their genome. Subtypes of coronaviruses circulating in humans (HCoV-229E, HCoV-OC43, HCoV-NL63 and HKU1-CoV) are mostly viruses that cause common colds [1-4].

On 31 December 2019, the WHO China Country Office reported cases of pneumonia with unknown etiology detected in Wuhan City, Hubei Province of China. On 7 January 2020, the agent was identified as a new coronavirus type (2019-nCoV) that has not previously been detected in humans.  Later, the name of 2019-nCoV disease was accepted as COVID-19.

The origin of COVID-19s is still under investigation. While wild animals illegally sold in the Huanan Seafood Wholesale Market are considered as the starting point of the outbreak, contamination from person to person and in health centers has been reported. The disease is thought to be transmitted through droplets.

Clinical pictures are newly defined. Since the number of cases in the publications is limited and the cases are different from each other, the mean incubation period may be different. According to scientific articles published so far, the incubation period accepted is 2–14 days. Common symptoms of infection are respiratory symptoms, fever, cough, and dyspnea.  In more severe cases, pneumonia, severe acute respiratory infection, kidney failure, and even death may occur.

Nucleic acid amplification tests to be used in diagnosis and COVID-19 sequence information have been recently shared and molecular (PCR) tests have been designed. Sequence data is essential to understand the origin of the virus and how it spreads.

Since the excretion and infectious time of the virus are unknown, for now, it is recommended to continue isolation measures during the patient’s stay at the healthcare facility. Taking standard and droplet isolation measures has come to the fore in cases suspected of COVID-19. Individuals diagnosed with COVID-19 should be followed and treated in multidisciplinary hospitals that can provide mechanical ventilatory support.  Treatment is supportive and aims at preventing secondary infections and complications since there is no specific antiviral treatment for COVID-19 and its pathogenesis is not fully known.  In new reports, remdesivir, chloroquine phosphate is recommended in COVID-19 pneumonias. Supplemental oxygen therapy for patients with respiratory distress, hypoxemia, and shock, careful administration of fluid therapy in patients when there is no evidence of shock, and use of empirical antimicrobials (antibiotics, influenza neuraminidase inhibitors, antifungals) for possible pathogens that can cause SARI are recommended. Antimicrobials are recommended to be given to patients with sepsis within the first hour after patient evaluation. Systemic corticosteroids are not routinely recommended for the treatment of viral pneumonia or ARDS unless they are indicated for another reason.  No vaccine for 2019-nCoV infection is available for now and studies continuous. [1-4].

Further details regarding the symptoms associated with 2019-nCoV can be found on the CDC website; The World Health Organization (WHO) also provides a document titled, “Clinical management of severe acute respiratory infection when novel coronavirus (2019-nCoV) infection is suspected.”  Timely information on the outbreak can be obtained from the WHO website. American Society of Anesthesia (ASA) Association has recommendations for anesthesia applications.


Personal protective equipment required for personnel who will be working at a distance of one meter to definite/possible COVID-19 cases: 

1. Gloves

2. Aprons (non-sterile, preferably liquid impermeable, and long sleeves)

3. Medical mask (surgical mask)

4. N95 / FFP2 or N99 / FFP3 mask (Only during the process that causes droplet/aerosolization)*

5. Face Protection

6. Glasses**

7. Liquid soap

8. Alcohol-based hand antiseptic should be kept in sufficient quantity by inpatient healthcare institutions.

*Procedures causing droplet/aerosolization: aspiration, bronchoscopy and bronchoscopic procedures, intubation, respiratory tract sampling

**Reusable glasses are cleaned according to the manufacturer’s recommendation. If there is no special recommendation made by the manufacturer, it should be disinfected with 70% ethyl alcohol and left to dry on its own in an appropriate environment. If the glasses are used again, the healthcare institution gives instructions on where the glasses will be removed, stored and disinfected.

To control the spread of the disease;

1. Possible and definite cases should be ensured to apply to separate areas in the hospitalby being informed as much as possible beforehand.

2. During the examination, analysis, and care of these patients, people who are not required at the time should not be present in the environment as much as possible.

3. Priority should be given in analyses.

4. Staff who will provide care should be separated if possible.

5. Wastes from possible/definite COVID-19 cases must be disposed of in accordance with the relevant standards.

6. If the healthcare provider who is dealing with the patient with COVID-19 infection sees any signs or symptoms that suggest an acute disease within 14 days after contact with the sick person, he/she should definitely notify the relevant physicians and take necessary measures immediately.

ASA Recommendations:

Personal protection

Healthcare professionals entering the room should use airborne precautions. Wear an N95 respirator mask, which filters 95 % of particles > 0.3 microns in diameter. Airborne precautions also call for the use of eye protection (e.g., goggles or a face shield), gowns and gloves to prevent the transmission of droplets and smaller airborne particles that settle on environmental surfaces and mucous membranes. Hand hygiene (using an alcohol-based hand rub) is essential before and after donning gloves.

Procedural planning

If anesthesia or surgery is planned:

1. Postpone non-urgent surgical procedures until the patient is determined to be non-infectious or not infected.

2. When surgery cannot be postponed, schedule procedures when a minimum number of health care workers and other patients are present in the surgical suite.

3. Leave as much time as possible before subsequent patient care (for the removal of airborne infectious contamination).

4. When possible, perform minor procedures in the patient’s room.


When transporting these patients for a procedure, don a fresh, clean gown and gloves to reduce contamination of environmental surfaces.

When using a bag-valve-mask device on these patients, a HEPA filter should be inserted between the breathing device and the patient.

Anesthesia Procedures

If general anesthesia is not required, the patient should continue to wear the surgical mask.

If general anesthesia is used:

1. Place a HEPA filter between the Y-piece of the breathing circuit and the patient’s mask, endotracheal tube or laryngeal mask airway.

2. Alternatively, for pediatric patients or other patients in whom the additional dead space or weight of the filter may be problematic, the HEPA filter should be placed on the expiratory end of the corrugated breathing circuit before expired gas enters the anesthesia machine.

3. The gas sampling tubing should also be protected by a HEPA filter, and gases exiting the gas analyzer should be scavenged and not allowed to return to the room air.

4. If available, use a closed suction system during airway suctioning. Closed suctioning systems may only be available in the critical care setting.

5. After the patient has left the operating room, keep the room vacant until 99.9 %air turnover is achieved (e.g., for an operating room with a minimum of 15 air exchanges per hour, 28 minutes at a minimum are needed).

6. After the case, clean and disinfect high-touch surfaces on the anesthesia machine and anesthesia work area with an Environmental Protection Agency-approved hospital disinfectant.

7. Consider disposable covers (e.g., plastic sheets for surfaces, long ultrasound probe sheath covers) to reduce contamination of equipment and other environmental surfaces.

Point of care ultrasound

A long sheath cover of the ultrasound unit and cable should be used for both vascular access procedures and regional blocks (contact with non-intact skin) and transthoracic exams (intact skin) to minimize contamination of the equipment.

Non-essential parts of the ultrasound cart may best be covered with drapes to minimize droplet exposure of other attached ultrasound probes, the electrical cords and supply bins that are frequently handled or accessed.


1. Li Q, Guan X, Wu P, Wang X, Zhou L, Tong Y, et al. Early Transmission Dynamics in Wuhan, China, of Novel Coronavirus–Infected Pneumonia. N Eng J Med. 2020; 382(13):1199-207. DOI: 10.1056/NEJMoa2001316

2. Zhou Y, Yang Y, Huang J, Jiang S, Du L. Advances in MERS-CoV Vaccines and Therapeutics Based on the Receptor-Binding Domain. Viruses.2019; 11(1). DOI: 10.3390/v11010060.

3. Gao J, Tian Z, Yang X. Breakthrough: Chloroquine phosphate has shown apparent efficacy in treatment of COVID-19 associated pneumonia in clinical studies. Biosci Trends. 2020; 14(1):72-73. DOI: 10.5582/bst.2020.01047.

4. Wan Y, Shang J, Graham R, Baric RS, Li F. Receptor recognition by novel coronavirus from Wuhan: An analysis based on decade-long structural studies of SARS Coronavirus. J Virol. 2020; 94(7).DOI: 10.1128/JVI.00127-20.

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Scoliosis secondary to osteoid osteoma: A case report of delayed diagnosis and 5-year follow-up

Our case of study is a 17 years old female patient who presented with painful scoliosis secondary to osteoid osteoma. The patient remained undiagnosed for years complaining of non-subsiding lumbar pain. Three years later, a thorough physical assesment and advanced radiological examination revealed that the patient’s complaint was related to an osteoid osteoma accompanying scoliosis. Surgical resection, fusion and instrumentation were applied.

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