Pediatric Respiratory Alkalosis Workup

  • Author: Mary C Mancini, MD, PhD; Chief Editor: Michael R Bye, MD   more...
 
Updated: May 28, 2009
 

Laboratory Studies

  • A simple step-wise approach proves useful for further workup in patients with respiratory alkalosis.
    • Step 1: Prove the presence of respiratory alkalosis by an ABG. A PCO2 less than 35 indicates alveolar hyperventilation. A pH greater than 7.4 is highly suggestive of alkalosis. When both are found, respiratory alkalosis is likely.
    • Step 2: Assess the chronicity of hyperventilation.[5] Reference range HCO3- with a pH greater than 7.45 suggests acute hyperventilation, whereas low HCO3- with a pH of 7.4-7.45 suggests a chronic partially compensated process.
    • Step 3: An arterial-alveolar oxygen gradient within the reference range and a pH greater than 7.4 is consistent with hyperventilation secondary to direct CNS stimulation, with normal lung function.
    • Step 4: Arterial pH less than 7.4 is usually observed with alveolar hyperventilation as compensation for metabolic acidosis (overcompensation for metabolic acidosis is very rare).
    • Step 5: Respiratory alkalosis is likely with hypoxemia with alveolar hyperventilation. However, determining if the alkalosis is caused by the hypoxia or if the hypoxia and the alkalosis are caused by the underlying pulmonary disease is difficult.
  • Measurement of arterial pH, HCO3-, and PCO2 are crucial. Transcutaneous or end-tidal PCO2 may be used in place of arterial PCO2; however, transcutaneous PCO2 requires normal skin perfusion, and end-tidal pCO2 is useful only in the presence of normal lung function and when no other acid-base disturbance is suspected. Furthermore, the noninvasive tests do not measure the pH.
  • A detailed history and careful physical examination should indicate an underlying disorder.
  • Standard nomograms (see image below) help diagnose simple acid-base disorders, despite the following limitations.Acid-base nomogram shows confidence bands for simpAcid-base nomogram shows confidence bands for simple acid-base disturbances. Conversion factor is 1 torr = 0.13 kPa.
    • They describe acid-base status in children with a steady-state condition. Hence, nomograms are not helpful for patients with rapidly changing status.
    • Nomograms lose precision at extremes.
    • Values falling in respiratory alkalosis may overlap with other mixed disorders and ultimately require clinical judgment.
  • Hyperventilation syndrome is often considered a diagnosis of exclusion. Physicians must consider other causes before making the diagnosis. However, in the typical patient with a normal alveolar-arterial oxygen gradient with an acute stress, the diagnosis can be made with confidence.
Next

Imaging Studies

  • Chest radiography may be indicated.
  • Ventilation/perfusion imaging, helical chest CT imaging, or CT angiography may be performed if pulmonary embolism is suspected.
  • CT imaging or MRI of the brain may be indicated if CNS pathology is suspected.
Previous
Next

Other Tests

  • Drug screening may be helpful.
Previous
Proceed to Treatment & Management
 
 
Contributor Information and Disclosures
Author

Mary C Mancini, MD, PhD  Professor and Chief of Cardiothoracic Surgery, Department of Surgery, Louisiana State University School of Medicine in Shreveport

Mary C Mancini, MD, PhD is a member of the following medical societies: American Association for Thoracic Surgery, American College of Surgeons, American Surgical Association, Phi Beta Kappa, Society of Thoracic Surgeons, and Southern Surgical Association

Disclosure: Nothing to disclose.

Coauthor(s)

Girish G Deshpande, MD, MBBS, FAAP  Assistant Professor, Department of Pediatrics, Division of Critical Care Medicine, Children's Hospital of Illinois at OSF St Francis Medical Center

Girish G Deshpande, MD, MBBS, FAAP is a member of the following medical societies: American Academy of Pediatrics

Disclosure: Nothing to disclose.

Specialty Editor Board

G Patricia Cantwell, MD, FCCM  Professor of Clinical Pediatrics, Chief, Division of Pediatric Critical Care Medicine, University of Miami, Leonard M Miller School of Medicine; Medical Director, Palliative Care Team, Director, Pediatric Critical Care Transport, Holtz Children's Hospital, Jackson Memorial Medical Center; Medical Manager, FEMA, Urban Search and Rescue, South Florida, Task Force 2; Pediatric Medical Director, Tilli Kids – Pediatric Initiative, Division of Hospice Care Southeast Florida, Inc

G Patricia Cantwell, MD, FCCM is a member of the following medical societies: American Academy of Hospice and Palliative Medicine, American Academy of Pediatrics, American Heart Association, American Trauma Society, National Association of EMS Physicians, Society of Critical Care Medicine, and Wilderness Medical Society

Disclosure: Nothing to disclose.

Mary L Windle, PharmD  Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Barry J Evans, MD  Assistant Professor of Pediatrics, Temple University Medical School; Director of Pediatric Critical Care and Pulmonology, Associate Chair for Pediatric Education, Temple University Children's Medical Center

Barry J Evans, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Chest Physicians, American Thoracic Society, and Society of Critical Care Medicine

Disclosure: Nothing to disclose.

Mary E Cataletto, MD  Director of Children's Sleep Services, Winthrop Sleep Disorders Center, Mineola, NY; Professor of Clinical Pediatrics, State University of New York at Stony Brook, Stony Brook, NY

Mary E Cataletto, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Chest Physicians

Disclosure: Shering Plough Pharmaceuticals Honoraria Consulting

Chief Editor

Michael R Bye, MD  Professor of Clinical Pediatrics, Division of Pulmonary Medicine, Columbia University College of Physicians and Surgeons; Attending Physician, Pediatric Pulmonary Medicine, Morgan Stanley Children's Hospital of New York Presbyterian, Columbia University Medical Center

Michael R Bye, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Chest Physicians, and American Thoracic Society

Disclosure: Nothing to disclose.

References

  1. Johnson RA. Respiratory alkalosis: a quick reference. Vet Clin North Am Small Anim Pract. May 2008;38(3):427-30, vii. [Medline].

  2. Ueda Y, Aizawa M, Takahashi A, Fujii M, Isaka Y. Exaggerated compensatory response to acute respiratory alkalosis in panic disorder is induced by increased lactic acid production. Nephrol Dial Transplant. Mar 2009;24(3):825-8. [Medline].

  3. Steiss JE, Wright JC. Respiratory alkalosis and primary hypocapnia in Labrador Retrievers participating in field trials in high-ambient-temperature conditions. Am J Vet Res. Oct 2008;69(10):1262-7. [Medline].

  4. [Guideline] Polson J, Lee WM. AASLD position paper: the management of acute liver failure. Hepatology. May 2005;41(5):1179-97. [Medline].

  5. Datta BN, Stone MD. Hyperventilation and hypophosphataemia. Ann Clin Biochem. Mar 2009;46:170-1. [Medline].

  6. Frangiosa A, De Santo LS, Anastasio P, De Santo NG. Acid-base balance in heart failure. J Nephrol. Mar-Apr 2006;19 Suppl 9:S115-20. [Medline].

  7. Hagiwara N, Ooboshi H, Ishibashi M, et al. Elevated cerebrospinal fluid lactate levels and the pathomechanism of calcification in Fahr's disease. Eur J Neurol. May 2006;13(5):539-43. [Medline].

  8. Myrianthefs PM, Briva A, Lecuona E, et al. Hypocapnic but not metabolic alkalosis impairs alveolar fluid reabsorption. Am J Respir Crit Care Med. Jun 1 2005;171(11):1267-71. [Medline]. [Full Text].

 
Previous
Next
 
Acid-base nomogram shows confidence bands for simple acid-base disturbances. Conversion factor is 1 torr = 0.13 kPa.
Schematic presentation of pathophysiology of hyperventilation.
 
 
 
All material on this website is protected by copyright, Copyright © 1994-2012 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.