```xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns4:query_definition xmlns:ns2="http://www.i2b2.org/xsd/cell/crc/psm/1.1/" xmlns:ns4="http://www.i2b2.org/xsd/cell/crc/psm/querydefinition/1.1/" xmlns:ns3="http://www.i2b2.org/xsd/cell/crc/psm/analysisdefinition/1.1/">
    <query_name>(t) Black-InfluenEssentiAcute h@11:10:11</query_name>
    <query_timing>ANY</query_timing>
    <specificity_scale>0</specificity_scale>
    <panel>
        <panel_number>1</panel_number>
        <panel_timing>ANY</panel_timing>
        <panel_accuracy_scale>100</panel_accuracy_scale>
        <invert>0</invert>
        <total_item_occurrences>1</total_item_occurrences>
        <item>
            <hlevel>3</hlevel>
            <item_name>Black</item_name>
            <item_key>\\i2b2_DEMO\i2b2\Demographics\Race\Black\</item_key>
            <item_icon>MA</item_icon>
            <tooltip>Demographic \ Race \ Black</tooltip>
            <class>ENC</class>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
    <panel>
        <panel_number>2</panel_number>
        <panel_timing>ANY</panel_timing>
        <panel_accuracy_scale>100</panel_accuracy_scale>
        <invert>0</invert>
        <total_item_occurrences>1</total_item_occurrences>
        <item>
            <hlevel>2</hlevel>
            <item_name>Influenza and pneumonia (j09-j18)</item_name>
            <item_key>\\ICD10_ICD9\Diagnoses\(J00-J99) Dise~45pn\(J09-J18) Infl~7z2l\</item_key>
            <item_icon>FA</item_icon>
            <tooltip>Diagnoses \ Diseases of the respiratory system (j00-j99) \ Influenza and pneumonia (j09-j18)</tooltip>
            <class>ENC</class>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
    <subquery_constraint>
        <first_query>
            <query_id>Observation A</query_id>
            <join_column>STARTDATE</join_column>
            <aggregate_operator>FIRST</aggregate_operator>
        </first_query>
        <operator>LESS</operator>
        <second_query>
            <query_id>Observation B</query_id>
            <join_column>STARTDATE</join_column>
            <aggregate_operator>FIRST</aggregate_operator>
        </second_query>
    </subquery_constraint>
    <subquery>
        <query_id>Observation A</query_id>
        <query_type>EVENT</query_type>
        <query_name>Observation A</query_name>
        <query_timing>SAMEINSTANCENUM</query_timing>
        <specificity_scale>0</specificity_scale>
        <panel>
            <panel_number>0</panel_number>
            <panel_timing>SAMEINSTANCENUM</panel_timing>
            <panel_accuracy_scale>100</panel_accuracy_scale>
            <invert>0</invert>
            <total_item_occurrences>1</total_item_occurrences>
            <item>
                <hlevel>4</hlevel>
                <item_name>Essential hypertension</item_name>
                <item_key>\\i2b2_DIAG\i2b2\Diagnoses\Circulatory system (390-459)\Hypertensive disease (401-405)\(401) Essential hypertension\</item_key>
                <item_icon>FA</item_icon>
                <tooltip>Diagnoses \ Circulatory system \ Hypertensive disease \ Essential hypertension</tooltip>
                <class>ENC</class>
                <item_is_synonym>false</item_is_synonym>
            </item>
        </panel>
    </subquery>
    <subquery>
        <query_id>Observation B</query_id>
        <query_type>EVENT</query_type>
        <query_name>Observation B</query_name>
        <query_timing>SAMEINSTANCENUM</query_timing>
        <specificity_scale>0</specificity_scale>
        <panel>
            <panel_number>0</panel_number>
            <panel_timing>SAMEINSTANCENUM</panel_timing>
            <panel_accuracy_scale>100</panel_accuracy_scale>
            <invert>0</invert>
            <total_item_occurrences>1</total_item_occurrences>
            <item>
                <hlevel>4</hlevel>
                <item_name>Acute hyperkalemia</item_name>
                <item_key>\\i2b2_DIAG\i2b2\Diagnoses\Metabolic and immunity disorders (270-279)\(276) Disorders of fluid, electro~\(276-7) Hyperpotassemia\</item_key>
                <item_icon>LA</item_icon>
                <tooltip>Diagnoses \ Metabolic and immunity disorders \ Disorders of fluid, electrolyte, and acid-base balance \ Hyperpotassemia</tooltip>
                <class>ENC</class>
                <item_is_synonym>true</item_is_synonym>
            </item>
            <item>
                <hlevel>4</hlevel>
                <item_name>Hyperkalemia</item_name>
                <item_key>\\i2b2_DIAG\i2b2\Diagnoses\Metabolic and immunity disorders (270-279)\(276) Disorders of fluid, electro~\(276-7) Hyperpotassemia\</item_key>
                <item_icon>LA</item_icon>
                <tooltip>Diagnoses \ Metabolic and immunity disorders \ Disorders of fluid, electrolyte, and acid-base balance \ Hyperpotassemia</tooltip>
                <class>ENC</class>
                <item_is_synonym>true</item_is_synonym>
            </item>
            <item>
                <hlevel>4</hlevel>
                <item_name>Chronic hyperkalemia</item_name>
                <item_key>\\i2b2_DIAG\i2b2\Diagnoses\Metabolic and immunity disorders (270-279)\(276) Disorders of fluid, electro~\(276-7) Hyperpotassemia\</item_key>
                <item_icon>LA</item_icon>
                <tooltip>Diagnoses \ Metabolic and immunity disorders \ Disorders of fluid, electrolyte, and acid-base balance \ Hyperpotassemia</tooltip>
                <class>ENC</class>
                <item_is_synonym>true</item_is_synonym>
            </item>
            <item>
                <hlevel>5</hlevel>
                <item_name>POTASSIUM (LOINC:2823-3)</item_name>
                <item_key>\\i2b2_LABS\i2b2\Labtests\LAB\(LLB16) Chemistry\(LLB22) Lytes/Renal/Glucose\K\LOINC:2823-3\</item_key>
                <item_icon>LA</item_icon>
                <tooltip>Labtests \ Chemistry \ Lytes/Renal/Glucose \ Potassium (Group:K) \ Potassium (LOINC:2823-3)</tooltip>
                <class>ENC</class>
                <constrain_by_value>
                    <value_operator>GE</value_operator>
                    <value_constraint>5</value_constraint>
                    <value_unit_of_measure>mmol/l</value_unit_of_measure>
                    <value_type>NUMBER</value_type>
                </constrain_by_value>
                <item_is_synonym>false</item_is_synonym>
            </item>
        </panel>
    </subquery>
</ns4:query_definition>

```

I want to find patients who have a diagnosis of essential hypertension (Observation A) and have an acute or chronic hyperkalemia diagnosis (Observation B) or high potassium levels (POTASSIUM) within the same encounter as Observation A. The query will look for the first occurrence of essential hypertension (Observation A) and compare it to the first occurrence of acute or chronic hyperkalemia or high potassium levels (Observation B) within the same encounter. The query will include patients with a diagnosis of essential hypertension and exclude those with any diagnosis related to influenza or pneumonia (Influenza and pneumonia). The query will also include patients with a diagnosis of essential hypertension and a diagnosis of acute or chronic hyperkalemia or high potassium levels within the same encounter, with the hyperkalemia or high potassium levels occurring after the essential hypertension diagnosis.