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Trial registered on ANZCTR

Registration number

ACTRN12619000716167

Ethics application status

Approved

Date submitted

4/04/2019

Date registered

13/05/2019

Date last updated

13/05/2019

Date data sharing statement initially provided

13/05/2019

Type of registration

Retrospectively registered

Titles & IDs

Public title

The association of high plasma potassium levels and high carbon dioxide levels in patients undergoing major laparoscopic abdominal surgery

Scientific title

The association of high plasma potassium levels and hypercarbia in patients undergoing major laparoscopic abdominal surgery

Secondary ID [1]

None

Universal Trial Number (UTN)

U1111-1230-9029

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Hypercarbia

Hyperkalaemia

Laparoscopic abdominal surgery

Condition category

Condition code

Surgery

Surgical techniques

Anaesthesiology

Anaesthetics

Blood

Other blood disorders

Metabolic and Endocrine

Other metabolic disorders

Intervention/exposure

Study type

Observational

Patient registry

False

Target follow-up duration

Target follow-up type

Description of intervention(s) / exposure

There is no participant involvement as this is a retrospective review of the patient medical records. Patients undergoing major laparoscopic surgery who develop hypercapnia during surgery will be retrospectively evaluated. From this retrospective cohort we will use the hospital electronic medical record system (CERNER) to identify patients with intraoperative hypercapnia, which will be defined as a partial pressure of arterial carbon dioxide (PaCO2) greater than 45 mmHg.

Intervention code [1]

Early Detection / Screening

Comparator / control treatment

Patients undergoing major laparoscopic surgery who do not develop hypercapnia during the surgery will be evaluated. These patients will be defined as having a partial pressure of arterial carbon dioxide (PaCO2) within normal values (PaCO2 35-45 mmHg)

Control group

Active

Outcomes

Primary outcome [1]

The intraoperative plasma potassium value will be recorded by an arterial blood gas during surgery. Measurement of plasma potassium levels in arterial blood
will be measured using an ABL 800 Blood Gas Analyser (Radiometer, Copenhagen,
Denmark) with a fully automated micromode eliminating the risk of user induced bias or loss of accuracy with very small samples. The value from the blood gas machine is stored electronically on our hospital's electronic medical record system (Cerner). This value will be extracted onto a data collection form.

Timepoint [1]

15 minutes from completion of surgery (i.e last surgical suture).

Secondary outcome [1]

Change in plasma potassium levels. The will be calculated as the difference between the first or baseline blood gas potassium value and the potassium value from the blood gas taken 15-minutes from completion of surgery.

The baseline and final blood gas potassium values will be recorded by an arterial blood gas during surgery. Measurement of plasma potassium levels in arterial blood
will be measured using an ABL 800 Blood Gas Analyser (Radiometer, Copenhagen,
Denmark) with a fully automated micromode eliminating the risk of user induced bias or loss of accuracy with very small samples. The value from the blood gas machine is stored electronically on our hospital's electronic medical record system (Cerner).

Timepoint [1]

This will be investigated by comparing the change in plasma potassium at completion of surgery compared to the baseline potassium value at start of surgery

Secondary outcome [2]

Development of any malignant arrhythmia. Malignant arrhythmia's will be defined as new onset atrial fibrillation, rapid atrial fibrillation (ventricular response rate > 100b/min), supra ventricular tachyarrythmias (narrow or wide complex), severe bradyarrythmias (heart rate less than 40 b/min), and junctional tachycardia, electrocardiographic evident of hyperkalaemia (new onset loss of p-waves, widening SRS complexes, new elevated T-waves). This will be assessed by the continuous 3 lead electrode attached to the patient as apart of standard anaesthesia care. Any arrhythmia is captured automatically by the anaesthesia monitor.

Timepoint [2]

During the intraoperative period

Secondary outcome [3]

Development of any malignant arrhythmia postoperatively. Malignant arrhythmia's will be defined as new onset atrial fibrillation, rapid atrial fibrillation (ventricular response rate > 100b/min), supra ventricular tachyarrythmias (narrow or wide complex), severe bradyarrythmias (heart rate less than 40 b/min), and junctional tachycardia, electrocardiographic evident of hyperkalaemia (new onset loss of p-waves, widening SRS complexes, new elevated T-waves). This be assessed by 12 lead EEG (electrocardiograph) that will be attached to the patient if there is any concern about the development of a post operative arrhythmia.

Timepoint [3]

From completion of surgery to hospital discharge

Secondary outcome [4]

Development of any Major Adverse Cardiovascular Events (MACE). The so-called "classical 3-point MACE" will be defined as defined as a composite of nonfatal myocardial infarction, development of heart failure and stroke. This will be assessed from data linkage to the patients electronic medical records (CERNER) and from the patients discharge summary on the electronic medical records.

Timepoint [4]

From completion of surgery to hospital discharge

Secondary outcome [5]

Other post surgical complications including acute kidney injury, sepsis, wound infection. This will be assessed from data linkage to the patients electronic medical records (CERNER) and from the patients discharge summary on the electronic medical records.

Timepoint [5]

Duration of hospital stay

Secondary outcome [6]

Length of hospital stay

Timepoint [6]

From completion of surgery until hospital discharge. This will be assessed from data linkage to the patients electronic medical records (CERNER) and from the patients discharge summary on the electronic medical records.

Secondary outcome [7]

Unexpected admission to ICU. This be be defined as any patient who is discharge to the ward, either from the post-operative anaesthesia recovery unit, the high dependency unit, or from the intensive care unit, who then requires an unexpected or unplanned admission, or re readmission if they have already been to ICU, for the management any altered physiological or haemodynamic states requiring intensive care therapy. This information will be assessed by data linkage to the hospitals electronic medical records.

Timepoint [7]

From completion of surgery until hospital discharge

Secondary outcome [8]

Medical emergency team (MET) call. At our institution, the MET team is activated whenever a patient meets predetermined criterion, which include acute changes in any of the following: conscious state; airway (noisy breathing/stridor); breathing (respiratory rate <8 or >30 breaths/min; pulse oximetry saturation <90% despite supplemental 10 litres/min oxygen therapy); circulation (heart rate <40 or >130 beats/min; systolic blood pressure <90 mmHg; urine output <50mL in 4 hours); bleeding (>100mL/hr); or if any member of staff is worried about the patient. In addition, an RRT is activated for any “code blue”. A “code blue” is activated whenever a patient suffers a cardiac or respiratory arrest. Once a MET call is activated, this is coded by the hospital clinical informatics unit. Access to this coding will be obtained by data linkage to the hospitals electronic medical records.

Timepoint [8]

From completion of surgery until hospital discharge

Secondary outcome [9]

Mortality. This will be assessed from data linkage to the patients electronic medical records (CERNER) which captures any mortality within 30 days post surgery.

Timepoint [9]

From completion of surgery to 28 days postoperatively

Eligibility

Key inclusion criteria

We will include:
1. adult patients greater than 40 years
2. undergoing major laparoscopic surgical procedure, and
3. require mechanical ventilation in the operating suite, and
4. require an arterial line as part of standard haemodynamic monitoring

Major surgery is defined as surgery greater than 2 hours duration and a hospital stay of at least 1 postoperative night

Minimum age

40 Years

Maximum age

No limit

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

1. Any non laparoscopic abdominal surgery
2. The patient has planned thoracic surgery
3. The patient has planned cardiac surgery
4. The patient is pregnant
5. The patient has planned intracranial neurosurgery

Study design

Purpose

Natural history

Duration

Longitudinal

Selection

Defined population

Timing

Retrospective

Statistical methods / analysis

This is a retrospective observational study comparing hyperkalaemia in hypercarbic and normocarbic patients undergoing major laparoscopic surgery surgery. Continuous data will be tested for normality and measures of central tendency will be compared as means and standard deviations (SD) using the Student t test for normally distributed variables; and as medians with interquartile range (IQR) using the Mann-Whitney U test for non-parametric variables. The primary outcome (plasma potassium levels at completion of surgery) will be made using t-test with Welsh's correction. A two-tailed p-value less than 0.05 will be considered as statistically significant. Logistic regression analysis will also be performed to adjust for baseline imbalances. Statistical analysis will be performed using PRISM 7.03 GraphPad software (La Jolla, CA, USA) and Stata 15 (Statacorp). This study will be reported following the STROBE statement checklist for observational studies.

Recruitment

Recruitment status

Completed

Date of first participant enrolment

Anticipated

Actual

14/04/2019

Date of last participant enrolment

Anticipated

Actual

3/05/2019

Date of last data collection

Anticipated

Actual

7/05/2019

Sample size

Target

286

Accrual to date

Final

286

Recruitment in Australia

Recruitment state(s)

VIC

Recruitment hospital [1]

Austin Health - Austin Hospital - Heidelberg

Recruitment postcode(s) [1]

3084 - Heidelberg

Funding & Sponsors

Funding source category [1]

Hospital

Name [1]

Austin Health

Address [1]

145 Studley Road, Heidlelberg, 3084, Victoria, Australia

Country [1]

Australia

Primary sponsor type

Hospital

Name

Austin Health

Address

145 Studley Road, Heidlelberg, 3084, Victoria, Australia

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Austin Health Research Ethics Commitee

Ethics committee address [1]

145 Studley Road, Austin Health, Heidlelberg, 3084, Victoria, Australia

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

04/04/2019

Approval date [1]

05/04/2019

Ethics approval number [1]

LNR/19/Austin/41

Summary

Brief summary

A retrospective observational study evaluating the association of hyperkalaemia in normocarbic and hypercarbic patients who have undergone laparoscopic abdominal surgery at Austin health.

This observational QI project will be conducted by the department of Anaesthesia at Austin Health. There is very limited research exploring the association between hypercarbia and potassium levels in an adult human population. It is known that hypercarbia detected in blood gas sampling correlates to processes that result in serum acidaemia, and it has also been theorized that an acidosis caused by hypercarbia may be related to changes in plasma potassium levels. As part of routine standard care at Austin Health, blood gas sampling is conducted intra-operatively and analysed in theatre using a blood gas analysis machine. Results of these studies are recorded in Austin Health’s electronic medical record system (CERNER).

This retrospective observational study aims to determine the relationship between hypercarbia and hyperkalaemia as there is the potential to developing life-threatening cardiac arrhythmias and cardiac arrest due to electrolyte imbalances.

This study aims to achieve the following objectives:

1)	Determination of the relationship between hypercarbia and hyperkalaemia
2)	Determine the magnitude of hyperkalaemic change from baseline
3)	Detail the subsequent potential clinical impact of hyperkalaemia in patients intraoperatively, and post-operatively
4)	Identify any patient factors that contribute to changes in serum potassium that may allow future identification of patient populations at risk of hyperkalaemia.
5)	Contribute to the limited human data on hyperkalaemia and acidosis.

As this is a quality improvement project, data will be collected retrospectively, and there will be no change to anaesthesia or surgical care in any way. All data collected has already been collected by normal hospital anaesthesia and surgical processes. No new data will be collected. There will be no clinical or patient contact involved at any time point for this project.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

A/Prof Laurence Weinberg

Address

Department of Anaesthesia, Austin Hospital
145 Studley Road,
Heidelberg, 3084, Victoria

Country

Australia

Phone

+61 3 9496 5000

Fax

+61 3 9459 6421

Laurence.Weinberg@austin.org.au

Contact person for public queries

Name

Laurence Weinberg

Address

Department of Anaesthesia, Austin Hospital
145 Studley Road,
Heidelberg, 3084, Victoria

Country

Australia

Phone

+61 3 9496 5000

Fax

+61 3 9459 6421

Laurence.Weinberg@austin.org.au

Contact person for scientific queries

Name

Laurence Weinberg

Address

Department of Anaesthesia, Austin Hospital
145 Studley Road,
Heidelberg, 3084, Victoria

Country

Australia

Phone

+61 3 9496 5000

Fax

+61 3 9459 6421

Laurence.Weinberg@austin.org.au

Data sharing statement

Will individual participant data (IPD) for this trial be available (including data dictionaries)?

No/undecided IPD sharing reason/comment

De-identified data will be available from the principle investigator upon reasonable request.

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	The association of acute hypercarbia and plasma potassium concentration during laparoscopic surgery: a retrospective observational study.	2021	https://dx.doi.org/10.1186/s12893-020-01034-w

N.B. These documents automatically identified may not have been verified by the study sponsor.

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