Difference between revisions of "High altitude pulmonary edema"

(Clinical Features)
(Clinical Features)
 
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== Background ==
+
==Background==
 
*Also known as HAPE
 
*Also known as HAPE
#Noncardiogenic pulm edema d/t increased microvascular pressure in the pulm circulation  
+
*Noncardiogenic [[pulmonary edema]] due to increased microvascular pressure in the pulmonary circulation
#Most lethal of the altitude illnesses  
+
**Hypoxic pulmonary vasoconstriction leads to [[pulmonary hypertension]]
#Occurs in <1/10,000 skiers in Colorado; 2-3% of Mt. McKinley climbers  
+
*Most lethal of the altitude illnesses  
#Typical pt is strong and fit; may not have symptoms of AMS before onset of HAPE  
+
*Occurs in <1/10,000 skiers in Colorado; 2-3% of Mt. McKinley climbers  
#Most commonly noticed on the second night at a new altitude  
+
*Typical patient is strong and fit; may not have symptoms of [[altered mental status]] before onset of HAPE  
#Risk Factors:
+
*Most commonly noticed on the second night at a new altitude  
##Heavy exertion
 
##Rapid ascent
 
##Cold
 
##Excessive salt ingestion
 
##Use of a sleeping medication
 
##Preexisting pulmonary HTN
 
##Preexisting respiratory infection (children)
 
##Previous history of HAPE
 
  
== Clinical Features ==
+
===Risk Factors===
#Early  
+
*Heavy exertion
##Dry cough, decreased exercise performance, dyspnea on exertion, localized rales  
+
*Rapid ascent
##Resting SaO2 is low for the altitude and drops markedly w/ exertion (aids in the dx)  
+
*Cold
#Late  
+
*Excessive salt ingestion
##Dyspnea at rest, marked weakness, productive cough, cyanosis, generalized rales  
+
*Use of a sleeping medication
##Tachycardia and tachypnea correlate with the severity of illness  
+
*Preexisting [[pulmonary hypertension]]
##Altered mental status and coma (from severe hypoxemia)  
+
*Preexisting respiratory infection (children)
#ECG
+
*Previous history of HAPE
##Right strain pattern
+
 
#CXR
+
==Clinical Features==
##Progresses from interstitial to localized-alveolar to generalized-alveolar infiltrates
+
===Early===
#ABG
+
*Dry [[cough]], decreased exercise performance, [[dyspnea]] on exertion, localized rales  
##hypoxemia with respiratory alkalosis
+
*Resting SaO2 is [[hypoxia|very low]] for the expected altitude but patients often appear clinically better than their saturation (aids in diagnosis)
 +
*Easily desaturates with exertion
 +
 
 +
===Late===
 +
*[[Dyspnea]] at rest, marked weakness, productive cough, cyanosis, generalized rales
 +
*Cough generates pink, frothy sputum
 +
*[[Tachycardia]] and [[tachypnea]] correlate with severity of illness  
 +
*[[Altered mental status]] and [[coma]] (from severe [[hypoxemia]])
  
 
==Differential Diagnosis==
 
==Differential Diagnosis==
 +
*[[Asthma]]
 +
*[[Bronchitis]]
 +
*[[CHF]]
 +
*[[COPD]]
 +
*[[MI]]
 +
 
{{High altitude DDX}}
 
{{High altitude DDX}}
  
== Treatment ==
+
{{Pulmonary edema types}}
#Immediate descent is treatment of choice  
+
 
##While pt is descending attempt to limit exertion as much as possible
+
==Evaluation==
#If cannot descend use combination of:  
+
[[File:Chest XR of HAPE.png|thumb|Chest x-ray of HAPE showing characteristic patchy alveolar infiltrates with right middle lobe predominance.]]
##Supplemental O2  
+
===Workup===
###Can completely resolve the pulmonary edema within 36-72hr  
+
*[[ECG]] - right strain pattern
##Hyperbaric bag  
+
*[[CXR]] - Progresses from interstitial → localized-alveolar → generalized-alveolar infiltrates
##Keep pt warm (cold stress elevates pulm artery pressure)  
+
*[[ABG]] - [[Hypoxemia]] with [[respiratory alkalosis]]
##Use expiratory positive airway pressure mask  
+
 
##Consider the medications listed below that are usually used for prevention
+
===Evaluation===
 +
*Clinical diagnosis
 +
 
 +
{{Expected SpO2 at altitude}}
 +
 
 +
==Management==
 +
[[File:Altitude flow sheet.png|thumb|High altitude management algorithm.]]
 +
*Immediate descent is treatment of choice - minimize exertion  
 +
*If cannot descend use combination of:  
 +
**Supplemental [[O2]] - An oxygen concentrator is often used at high altitude ski resorts after the patient is titrated down to nasal cannula. A portable oxygen tank is used for ambulation. Can completely resolve the pulmonary edema within 36-72hr  
 +
**Hyperbaric bag - (e.g. Gamow Bag). Should not delay descent, if possible.
 +
**Keep patient warm (cold stress elevates pulmonary artery pressure)  
 +
**Use expiratory positive airway pressure mask  
 +
**[[Nifedipine]] 30mg ER q12hr (or 20mg normal-release q8hr)<ref>Luks AM, McIntosh SE, Grissom CK, et al. Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness: 2014 Update. Wilderness & Environmental Medicine. 2014(25): S4–S14)</ref>
 +
***May consider the other medications listed below that are usually used for prevention
  
== Disposition ==
+
==Disposition==
#Admission  
+
*Admission  
##Warranted for severe illness that does not respond immediately to descent  
+
**Warranted for severe illness that does not respond immediately to descent  
#Discharge  
+
*Discharge  
##Progressive clinical and X-ray improvement and a PaO2 of 60mmHg or SaO2>90%
+
**Progressive clinical and X-ray improvement and a PaO2 of 60mmHg or SaO2>90%
 +
*May re-ascend in 2-3 days if mild-moderate symptoms resolved that only required descent as the intervention
  
== Prevention ==
+
==Prevention==
#Nifedipine 20mg q8hr while ascending is effective prophylaxis in pts who had HAPE before
+
*[[Nifedipine]] 20mg q8hr or 30mg ER q12hr while ascending is effective prophylaxis in patients with prior episodes of HAPE  
#Tadalafil 10mg BID 24hr prior to ascent  
+
*[https://nizagara-online.net/tadalafil/ Tadalafil] 10mg BID 24hr prior to ascent '''OR''' [[Sildenafil]] 50mg q8hr
#Salmeterol inhaled BID
+
*[[Salmeterol]] 125 mcg inhaled BID
 +
*[[Acetazolamide]] 125mg BID for prevention of hypoxia
  
 
==See Also==
 
==See Also==
[[High Altitude Medicine]]
+
*[[High Altitude Medicine]]
  
==Source==
+
==References==
Tintinalli
+
<references/>
  
[[Category:Environ]]
+
[[Category:Environmental]]

Latest revision as of 19:29, 2 March 2020

Background

  • Also known as HAPE
  • Noncardiogenic pulmonary edema due to increased microvascular pressure in the pulmonary circulation
  • Most lethal of the altitude illnesses
  • Occurs in <1/10,000 skiers in Colorado; 2-3% of Mt. McKinley climbers
  • Typical patient is strong and fit; may not have symptoms of altered mental status before onset of HAPE
  • Most commonly noticed on the second night at a new altitude

Risk Factors

  • Heavy exertion
  • Rapid ascent
  • Cold
  • Excessive salt ingestion
  • Use of a sleeping medication
  • Preexisting pulmonary hypertension
  • Preexisting respiratory infection (children)
  • Previous history of HAPE

Clinical Features

Early

  • Dry cough, decreased exercise performance, dyspnea on exertion, localized rales
  • Resting SaO2 is very low for the expected altitude but patients often appear clinically better than their saturation (aids in diagnosis)
  • Easily desaturates with exertion

Late

Differential Diagnosis

High Altitude Illnesses

Pulmonary Edema Types

Pulmonary capillary wedge pressure <18 mmHg differentiates noncardiogenic from cardiogenic pulmonary edema[1]

Evaluation

Chest x-ray of HAPE showing characteristic patchy alveolar infiltrates with right middle lobe predominance.

Workup

Evaluation

  • Clinical diagnosis

Expected SpO2 and PaO2 levels at altitude[2]

Altitude SpO2 PaO2 (mm Hg)
1,500 to 3,500 m (4,900 to 11,500 ft) about 90% 55-75
3,500 to 5,500 m (11,500 to 18,000 ft) 75-85% 40-60
5,500 to 8,850 m (18,000 to 29,000 ft) 58-75% 28-40

Management

High altitude management algorithm.
  • Immediate descent is treatment of choice - minimize exertion
  • If cannot descend use combination of:
    • Supplemental O2 - An oxygen concentrator is often used at high altitude ski resorts after the patient is titrated down to nasal cannula. A portable oxygen tank is used for ambulation. Can completely resolve the pulmonary edema within 36-72hr
    • Hyperbaric bag - (e.g. Gamow Bag). Should not delay descent, if possible.
    • Keep patient warm (cold stress elevates pulmonary artery pressure)
    • Use expiratory positive airway pressure mask
    • Nifedipine 30mg ER q12hr (or 20mg normal-release q8hr)[3]
      • May consider the other medications listed below that are usually used for prevention

Disposition

  • Admission
    • Warranted for severe illness that does not respond immediately to descent
  • Discharge
    • Progressive clinical and X-ray improvement and a PaO2 of 60mmHg or SaO2>90%
  • May re-ascend in 2-3 days if mild-moderate symptoms resolved that only required descent as the intervention

Prevention

  • Nifedipine 20mg q8hr or 30mg ER q12hr while ascending is effective prophylaxis in patients with prior episodes of HAPE
  • Tadalafil 10mg BID 24hr prior to ascent OR Sildenafil 50mg q8hr
  • Salmeterol 125 mcg inhaled BID
  • Acetazolamide 125mg BID for prevention of hypoxia

See Also

References

  1. Clark SB, Soos MP. Noncardiogenic Pulmonary Edema. In: StatPearls. Treasure Island (FL): StatPearls Publishing; October 1, 2020.
  2. Gallagher, MD, Scott A.; Hackett, MD, Peter (August 28, 2018). "High altitude pulmonary edema". UpToDate. Retrieved May 2, 2019.
  3. Luks AM, McIntosh SE, Grissom CK, et al. Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness: 2014 Update. Wilderness & Environmental Medicine. 2014(25): S4–S14)