Difference between revisions of "High altitude pulmonary edema"

(Prevention)
 
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==Background==
 
==Background==
 
*Also known as HAPE
 
*Also known as HAPE
*Noncardiogenic pulmonary edema due to increased microvascular pressure in the pulmonary 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]]
 +
*Most lethal of the altitude illnesses with mortality approaching 50% if descent is not completed in a timely manner <ref>Lobenhoffer HP, Zink RA, et al. High altitude pulmonary edema: analysis of 166 cases. In: Brendel W, Zink RA, editors. High Altitude Physiology and Medicine. New York, NT: Springer-Verlag; 1982. pp. 219–231</ref>
 
*Occurs in <1/10,000 skiers in Colorado; 2-3% of Mt. McKinley climbers  
 
*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  
+
*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  
 
*Most commonly noticed on the second night at a new altitude  
  
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*Excessive salt ingestion  
 
*Excessive salt ingestion  
 
*Use of a sleeping medication  
 
*Use of a sleeping medication  
*Preexisting pulmonary hypertension  
+
*Preexisting [[pulmonary hypertension]]
 
*Preexisting respiratory infection (children)  
 
*Preexisting respiratory infection (children)  
 
*Previous history of HAPE
 
*Previous history of HAPE
 +
 +
===Pathophysiology===
 +
*Multiple pathways but thought to be due to an exaggerated pulmonary artery pressure elevation in response to hypoxia <ref>Bärtsch P. High altitude pulmonary edema. Med Sci Sports Exerc. 1999;31(1 Suppl):S23-27.</ref> and the following hypothesis:
 +
**Breakdown of the alveolar/endothelial barrier leading to increased pulmonary vascular endothelial permeability
 +
**Normal wedge pressure, which distinguishes this pathophysiology from heart failure <ref>Hultgren HN, Lopez CE, Lundberg E, Miller H. Physiologic studies of pulmonary edema at high altitude. Circulation. 1964;29(3):393-408.</ref>
 +
**Increased intra-cranial pressure which can lead to pulmonary edema <ref>Ducker TB, Simmons RL. Increased intracranial pressure and pulmonary edema. 2. The hemodynamic response of dogs and monkeys to increased intracranial pressure. J Neurosurg. 1968;28(2):118-123.</ref>
  
 
==Clinical Features==
 
==Clinical Features==
*Early  
+
===Early===
**Dry cough, decreased exercise performance, dyspnea on exertion, localized rales  
+
*Dry [[cough]], decreased exercise performance, prolonged exercise recover time, [[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)
+
*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  
+
===Late===
**Tachycardia and tachypnea correlate with severity of illness  
+
*[[Dyspnea]] at rest, marked weakness, productive cough, cyanosis, generalized rales
**Altered mental status and coma (from severe hypoxemia)
+
*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==
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*[[COPD]]
 
*[[COPD]]
 
*[[MI]]
 
*[[MI]]
 +
*[[Pneumonia]]
 +
*[[PE]]
 +
*[[Pneumonitis]]
 +
*Pulmonary edema of any cause (cardiogenic, neurogenic, toxic, immersion, etc)
  
 
{{High altitude DDX}}
 
{{High altitude DDX}}
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==Evaluation==
 
==Evaluation==
 +
[[File:Chest XR of HAPE.png|thumb|Chest x-ray of HAPE showing characteristic patchy alveolar infiltrates with right middle lobe predominance.]]
 
===Workup===
 
===Workup===
 
*[[ECG]] - right strain pattern  
 
*[[ECG]] - right strain pattern  
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===Evaluation===
 
===Evaluation===
*Clinical diagnosis
+
*The Lake Louise Consensus Definition of HAPE<ref>Sutton JR, Coates G, Houston CS, eds. Hypoxia and Mountain Medicine: Proceedings of the 7th International Hypoxia Symposium, Held at Lake Louise, Canada, February 1991. 1st ed. Pergamon Press; 1992.</ref>
 +
**At least two of the following symptoms:
 +
***[[Dyspnea]] at rest
 +
***[[Cough]]
 +
***Weakness or decreased exercise performance
 +
***Chest tightness or congestion
 +
**As well as two of the following signs:
 +
***Crackles or wheezing in at least one lung field
 +
***Central cyanosis
 +
***[[Tachypnea]]
 +
***[[Tachycardia]]
 +
 
 +
 
 +
*Clinical Severity Grading <ref>Marticorena E, Hultgren HN. Evaluation of therapeutic methods in high altitude pulmonary edema. Am J Cardiol. 1979;43(2):307-312.</ref>
 +
{| class="wikitable"
 +
|-
 +
! Grade !! HR !! RR !! Symptoms
 +
|-
 +
| I || < 100 || < 20 || Dyspnea on exertion; can perform light activity
 +
|-
 +
| II || 110-120 || 20-30 || Dyspnea on slight effort; cannot perform light activity, cough, dyspnea at rest
 +
|-
 +
| II || 121-140|| 31-40 || Severe dyspnea, recurrent productive cough, wheezing, cyanosis
 +
|-
 +
| IV || >140 || > 40 || Stupor, coma, unable to stand/walk, severe cyanosis, blood copious sputum
 +
|}
 +
 
 +
{{Expected SpO2 at altitude}}
  
 
==Management==
 
==Management==
 +
[[File:Altitude flow sheet.png|thumb|High altitude management algorithm.]]
 
*Immediate descent is treatment of choice - minimize exertion  
 
*Immediate descent is treatment of choice - minimize exertion  
 
*If cannot descend use combination of:  
 
*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  
+
**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.  
 
**Hyperbaric bag - (e.g. Gamow Bag). Should not delay descent, if possible.  
 
**Keep patient warm (cold stress elevates pulmonary artery pressure)  
 
**Keep patient warm (cold stress elevates pulmonary artery pressure)  
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==Prevention==
 
==Prevention==
 +
*Slow ascent at a rate no more than 300-350m (1000ft) per day above 2500m (8000ft)<ref>Rosen JM. High Altitude Disease in Adults. www.uptodate.com. Version 14.1:2005. (On line review and treatment guidelines)</ref>
 
*[[Nifedipine]] 20mg q8hr or 30mg ER q12hr while ascending is effective prophylaxis in patients with prior episodes of HAPE  
 
*[[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
+
*[https://nizagara-online.net/tadalafil/ Tadalafil] 10mg BID 24hr prior to ascent '''OR''' [[Sildenafil]] 50mg q8hr
 
*[[Salmeterol]] 125 mcg inhaled BID
 
*[[Salmeterol]] 125 mcg inhaled BID
 
*[[Acetazolamide]] 125mg BID for prevention of hypoxia
 
*[[Acetazolamide]] 125mg BID for prevention of hypoxia
 +
*[[Dexamethasone]] 8mg PO BID<ref>Maggiorini M, Brunner-La Rocca H-P, Peth S, et al. Both tadalafil and dexamethasone may reduce the incidence of high-altitude pulmonary edema: a randomized trial. Ann Intern Med. 2006;145(7):497-506.</ref>
  
 
==See Also==
 
==See Also==

Latest revision as of 22:50, 22 May 2021

Background

  • Also known as HAPE
  • Noncardiogenic pulmonary edema due to increased microvascular pressure in the pulmonary circulation
  • Most lethal of the altitude illnesses with mortality approaching 50% if descent is not completed in a timely manner [1]
  • 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

Pathophysiology

  • Multiple pathways but thought to be due to an exaggerated pulmonary artery pressure elevation in response to hypoxia [2] and the following hypothesis:
    • Breakdown of the alveolar/endothelial barrier leading to increased pulmonary vascular endothelial permeability
    • Normal wedge pressure, which distinguishes this pathophysiology from heart failure [3]
    • Increased intra-cranial pressure which can lead to pulmonary edema [4]

Clinical Features

Early

  • Dry cough, decreased exercise performance, prolonged exercise recover time, 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[5]

Evaluation

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

Workup

Evaluation

  • The Lake Louise Consensus Definition of HAPE[6]
    • At least two of the following symptoms:
      • Dyspnea at rest
      • Cough
      • Weakness or decreased exercise performance
      • Chest tightness or congestion
    • As well as two of the following signs:


  • Clinical Severity Grading [7]
Grade HR RR Symptoms
I < 100 < 20 Dyspnea on exertion; can perform light activity
II 110-120 20-30 Dyspnea on slight effort; cannot perform light activity, cough, dyspnea at rest
II 121-140 31-40 Severe dyspnea, recurrent productive cough, wheezing, cyanosis
IV >140 > 40 Stupor, coma, unable to stand/walk, severe cyanosis, blood copious sputum

Expected SpO2 and PaO2 levels at altitude[8]

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)[9]
      • 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

  • Slow ascent at a rate no more than 300-350m (1000ft) per day above 2500m (8000ft)[10]
  • 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
  • Dexamethasone 8mg PO BID[11]

See Also

References

  1. Lobenhoffer HP, Zink RA, et al. High altitude pulmonary edema: analysis of 166 cases. In: Brendel W, Zink RA, editors. High Altitude Physiology and Medicine. New York, NT: Springer-Verlag; 1982. pp. 219–231
  2. Bärtsch P. High altitude pulmonary edema. Med Sci Sports Exerc. 1999;31(1 Suppl):S23-27.
  3. Hultgren HN, Lopez CE, Lundberg E, Miller H. Physiologic studies of pulmonary edema at high altitude. Circulation. 1964;29(3):393-408.
  4. Ducker TB, Simmons RL. Increased intracranial pressure and pulmonary edema. 2. The hemodynamic response of dogs and monkeys to increased intracranial pressure. J Neurosurg. 1968;28(2):118-123.
  5. Clark SB, Soos MP. Noncardiogenic Pulmonary Edema. In: StatPearls. Treasure Island (FL): StatPearls Publishing; October 1, 2020.
  6. Sutton JR, Coates G, Houston CS, eds. Hypoxia and Mountain Medicine: Proceedings of the 7th International Hypoxia Symposium, Held at Lake Louise, Canada, February 1991. 1st ed. Pergamon Press; 1992.
  7. Marticorena E, Hultgren HN. Evaluation of therapeutic methods in high altitude pulmonary edema. Am J Cardiol. 1979;43(2):307-312.
  8. Gallagher, MD, Scott A.; Hackett, MD, Peter (August 28, 2018). "High altitude pulmonary edema". UpToDate. Retrieved May 2, 2019.
  9. 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)
  10. Rosen JM. High Altitude Disease in Adults. www.uptodate.com. Version 14.1:2005. (On line review and treatment guidelines)
  11. Maggiorini M, Brunner-La Rocca H-P, Peth S, et al. Both tadalafil and dexamethasone may reduce the incidence of high-altitude pulmonary edema: a randomized trial. Ann Intern Med. 2006;145(7):497-506.