WikiAnesthesia - User contributions [en]

Syndrome of inappropriate antidiuretic hormone secretion

2025-06-29T17:48:06Z

JessicaLeungMD: Intraoperative management

{{Infobox comorbidity
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Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a condition in which ''excess'' anti-diuretic hormone (ADH) - also known as vasopressin - is produced. Downstream effects include 1. retention of excess water which can lead to cerebral edema/seizures/coma/death, 2. hyponatremia which can lead to arrhythmias and - if sodium corrected is attempted - potentially iatrogenic Osmotic demyelination syndrome (OSD)/Central pontine myelinolysis (CPM).

==Anesthetic implications==

===Preoperative optimization===

* Evaluate overall sodium trend
** Most anesthesiologists would consider delaying case if sodium x<130
** Ideally sodium should be corrected to normal limits or at least ''stabilized or trending towards correction'' prior to surgery
*** Uncorrected sodium levels merits discussion with internal medicine and surgery.

===Intraoperative management===

* Serial ABG to monitor serum sodium
** concern for ''overly rapid correction'' - potentially leading to OSD or CPM.
*** Maintain sodium correction to 0.5mmol/L/hr with goal of 4-8mmol/L in ''24 hours''<ref>{{Cite web|title=The Resuscitationist’s Approach to Severe Hyponatremia|url=https://www.acep.org/criticalcare/newsroom/newsroom-articles/september2022/the-resuscitationists-approach-to-severe-hyponatremia|access-date=2025-06-29|website=www.acep.org|language=en}}</ref>
***
* Avoid hypotonic fluids
** half normal saline
** dextrose in water
** LR - can consider but requires very close monitoring of sodium levels
* Preferred fluids
** Hypertonic saline

===Postoperative management===

==Related surgical procedures==

==Pathophysiology==
General Mechanism of Action of ADH

* ADH is a hormone produced by the hypothalamus, then stored and released via the posterior pituitary gland
* ADH is responsible for mechanisms pertaining to water retention via upregulation of aquaporin channels in renal nephrons to increase water re-absorption. ADH's main effect leads to increased fluid volume while decreasing serum sodium concentration and decreasing urinary output volume.

Consequences

Causes

* Cancer
** Brain tumors
** Small Cell Lung Cancer
** Lymphoma
* Central Nervous System
** Brain Surgery - especially pituitary gland surgery
** Brain tumors
** Meningitis
** Encephalitis
** Brain trauma
**Hypopituitarism
**Stroke
*Guillain-Barre
*Heart Failure
*Lung Pathology
**Pneumonia
*Medications
**SSRIs
**Anti-neoplastic drugs
**Anti-psychotics
*Acute stressors
**pain
**Nausea
*Hypothoridism
*HIV infection

==Signs and symptoms==
[[File:Siadh vs di vs cerebral salt wasting.png|thumb]]Symptoms

* Cerebral
** Altered mental status
** Seizures
** Loss of balance/coordination
** Coma
* GI
** Nausea
** Emesis
* Musculoskeletal
** Muscle cramps
** Muscle weakness

==Diagnosis==

* Hyponatremia (serum) x< 135 mEq/L
* High urine osmolality: 100+ mOsm/kg
* High Urine sodium levels 40+ mEq/L
* Euvolemic or fluid overload state

==Treatment==

* Overall treatment is to remove excess water from the body
* Diuretics
* H20 restriction
* Demeclocycline (off-label)
** a tetracycline antibiotic that is used off-label to treat SIADH by decreasing renal response to ADH
* Treat inciting etiology

==Epidemiology==
Risk factors for SIADH

* Increasing age
* Hospitalization
* Lung cancer
* Cerebral pathology/manipulation

==References==
<ref>{{Cite journal|last=Leung|first=Alexander A.|last2=McAlister|first2=Finlay A.|last3=Rogers|first3=Selwyn O., Jr|last4=Pazo|first4=Valeria|last5=Wright|first5=Adam|last6=Bates|first6=David W.|date=2012-10-22|title=Preoperative Hyponatremia and Perioperative Complications|url=https://doi.org/10.1001/archinternmed.2012.3992|journal=Archives of Internal Medicine|volume=172|issue=19|pages=1474–1481|doi=10.1001/archinternmed.2012.3992|issn=0003-9926}}</ref>
[[Category:Comorbidities]]

Syndrome of inappropriate antidiuretic hormone secretion

2025-06-29T17:24:57Z

JessicaLeungMD: Started SIADH page, filled out pathophysiology, made chart for differential diagnosis and treatment

{{Infobox comorbidity
| other_names =
| anesthetic_relevance =
| specialty =
| signs_symptoms =
| diagnosis =
| treatment =
| image =
| caption =
}}

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a condition in which ''excess'' anti-diuretic hormone (ADH) - also known as vasopressin - is produced. Downstream effects include 1. retention of excess water which can lead to cerebral edema/seizures/coma/death, 2. hyponatremia which can lead to arrhythmias and - if sodium corrected is attempted - potentially iatrogenic Osmotic demyelination syndrome (OSD)/Central pontine myelinolysis (CPM).

==Anesthetic implications==

===Preoperative optimization===

* Evaluate overall sodium trend
** Most anesthesiologists would consider delaying case if sodium x<130
** Ideally sodium should be corrected to normal limits or at least ''stabilized or trending towards correction'' prior to surgery
*** Uncorrected sodium levels merits discussion with internal medicine and surgery.

===Intraoperative management===

===Postoperative management===

==Related surgical procedures==

==Pathophysiology==
General Mechanism of Action of ADH

* ADH is a hormone produced by the hypothalamus, then stored and released via the posterior pituitary gland
* ADH is responsible for mechanisms pertaining to water retention via upregulation of aquaporin channels in renal nephrons to increase water re-absorption. ADH's main effect leads to increased fluid volume while decreasing serum sodium concentration and decreasing urinary output volume.

Consequences

Causes

* Cancer
** Brain tumors
** Small Cell Lung Cancer
** Lymphoma
* Central Nervous System
** Brain Surgery - especially pituitary gland surgery
** Brain tumors
** Meningitis
** Encephalitis
** Brain trauma
**

==Signs and symptoms==
[[File:Siadh vs di vs cerebral salt wasting.png|thumb]]

==Diagnosis==

==Treatment==

===Medication===

===Surgery===

===Prognosis===

==Epidemiology==

==References==
<ref>{{Cite journal|last=Leung|first=Alexander A.|last2=McAlister|first2=Finlay A.|last3=Rogers|first3=Selwyn O., Jr|last4=Pazo|first4=Valeria|last5=Wright|first5=Adam|last6=Bates|first6=David W.|date=2012-10-22|title=Preoperative Hyponatremia and Perioperative Complications|url=https://doi.org/10.1001/archinternmed.2012.3992|journal=Archives of Internal Medicine|volume=172|issue=19|pages=1474–1481|doi=10.1001/archinternmed.2012.3992|issn=0003-9926}}</ref>
[[Category:Comorbidities]]

NPO guidelines

2025-06-04T04:39:46Z

JessicaLeungMD: Wrote new NPO guidelines article

NPO stands for "Nil Per Os" - translating to "nothing by mouth."

NPO guidelines are enforced prior to providing anesthesia for surgeries as a method to decrease risk of aspiration. The NIH estimates that anesthesia related aspiration occurs 1 in every 2000-3000 cases; of those cases, 50% of them continue to develop further pulmonary complications such as pneumonitis or aspiration pneumonia. <ref>{{Cite journal|last=Nason|first=Katie S.|date=2015-08|title=Acute Intraoperative Pulmonary Aspiration|url=https://pmc.ncbi.nlm.nih.gov/articles/PMC4517287/|journal=Thoracic Surgery Clinics|volume=25|issue=3|pages=301–307|doi=10.1016/j.thorsurg.2015.04.011|issn=1558-5069|pmc=4517287|pmid=26210926}}</ref> Aspirated-related events can become life-threatening; one study estimates that perioperative aspiration pneumonia carries a 27% mortality rate. <ref>{{Cite journal|last=Studer|first=Peter|last2=Räber|first2=Genevieve|last3=Ott|first3=Daniel|last4=Candinas|first4=Daniel|last5=Schnüriger|first5=Beat|date=2016-03-01|title=Risk factors for fatal outcome in surgical patients with postoperative aspiration pneumonia|url=https://www.sciencedirect.com/science/article/pii/S1743919116000522|journal=International Journal of Surgery|volume=27|pages=21–25|doi=10.1016/j.ijsu.2016.01.043|issn=1743-9191}}</ref>

Under general anesthesia, 1. protective airway reflexes such involving the epiglottis and swallowing are impaired, and 2. multiple anesthetic agents can decrease lower esophageal sphincter (LES) tone. To minimize aspiration, current medical protocols rely on patient fasting to minimize gastric content available to aspirate.

NPO guidelines are determined by the carbohydrate, fat, and protein content of the foods consumed. Generally, carbohydrates pass through the stomach most rapidly, while fats remain in the stomach for the longest.
{| class="wikitable"
|+
!Meal/Food
!Hours to wait before starting elective surgery
|-
|Heavy Meal (high protein and fat content)
|8 hours
|-
|Light Meal (toast, crackers, low fat-low protein)
|6 hours
|-
|Infant Formula
|6 hours
|-
|Breastmilk
|4 hours
|-
|Clears (water, black coffee, plain tea, Ensure Clear, Boost Breeze, fruit juice no pulp)
|2 hours<ref>{{Cite web|title=NPO Guidelines - Anesthesiology {{!}} UCLA Health|url=https://www.uclahealth.org/departments/anes/referring-providers/npo-guidelines|access-date=2025-06-04|website=www.uclahealth.org|language=en}}</ref>
|-
|
|
|-
|Miscellaneous
|
|-
|Gum
|Do not delay case, but do not encourage<ref>{{Cite web|title=Chewing gum while fasting before surgery is safe, study finds|url=https://www.asahq.org/about-asa/newsroom/news-releases/2014/10/chewing-gum-while-fasting-before-surgery-is-safe-study-finds|access-date=2025-06-04|website=www.asahq.org}}</ref>
|}
Notably many medical floors keep to a generalized "NPO at midnight" protocol the night prior to surgery to prevent accidental oral intake which may delay surgical cases the next morning. However, without providing a maintenance fluid via a peripheral IV, these restrictive protocols can lead to relatively volume depletion for patients whose surgeries are scheduled for late afternoon/evening.

LMA Supreme

2025-06-04T04:08:53Z

JessicaLeungMD: Added additional features regarding OG tube port and added column for OG tube size vs LMA supreme size

A laryngeal mask airway is a supraglottic airway device which allows for controlled ventilation and delivery of anesthetic gases without requiring laryngoscopy or instrumentation of the trachea. It is considered to be a less secure airway device than an [[endotracheal tube]].

LMA® Supreme™ Airway is advertised to increase efficacy and safety versus first-generation devices including decreased aspiration risk.

Features include:

*Compared to traditional LMA, LMA supreme has a ''curved'' rigid airway shape
*Elongated cuff to help with smooth insertion
* Distal tip with laryngeal and esophageal seals
* Integrated bite block
* Tab to help with securing device
*Additional channel to allow for insertion of oral-gastric tube insertion to decompress stomach
**however, it does not provide a protected airway as a cuffed endotracheal tube would

Sizing chart:
{| class="wikitable"
|+
!LMA Size
!Weight (KG)
!Max OG tube (Fr)
|-
|1
|<5
|
|-
|1.5
|5-10
|
|-
|2
|10-20
|
|-
|2.5
|20-30
|10
|-
|3
|30-50
|14
|-
|4
|50-70
|14
|-
|5
|70-100
|14
|}