We're unable to sign you in at this time. Please try again in a few minutes.
We were able to sign you in, but your subscription(s) could not be found. Please try again in a few minutes.
There may be a problem with your account. Please contact the AMA Service Center to resolve this issue.
Contact the AMA Service Center:
Telephone: 1 (800) 262-2350 or 1 (312) 670-7827  *   Email: subscriptions@jamanetwork.com
Error Message ......
Article |

Measurement of Gastrointestinal Intramucosal pH Is a Poor Guide to Tolerable Levels of Anemia During Isovolemic Hemodilution in a Canine Model of Coronary Stenosis

Michael Layland; Michael G. Mythen, FRCA, MD; Kuo-Yang Wang, MD; Pierre Albaladejo, MD; Bruce J. Leone, MD
Arch Surg. 1997;132(5):547-552. doi:10.1001/archsurg.1997.01430290093019.
Text Size: A A A
Published online


Objective:  To determine the relationship between gastrointestinal intramucosal pH and myocardial oxygenation during isovolemic hemodilution in dogs with critical coronary artery stenoses.

Design:  Prospective sequential evaluation of ileal intramucosal pH and regional myocardial function of a critically perfused area of myocardial tissue in a canine model of normovolemic hemodilution.

Setting:  A research laboratory.

Subjects:  Fifteen dogs.

Interventions:  A micrometer snare was placed around a main coronary artery (8 left anterior descending artery, 7 right coronary artery). Three pairs of sonomicrometer crystals were placed in the heart to measure regional myocardial contraction. A gastrointestinal tonometer was placed in the ileum and used to measure luminal Pco2. This Pco2 value was used to calculate the ileal intramucosal pH. The animals underwent normovolemic hemodilution until myocardial ischemia occurred in the region supplied by the snared vessel. Measurements were continued for a further 40 minutes.

Measurements and Main Results:  Following instrumentation, stabilization, and critical constriction of a coronary vessel, percentage changes in systolic shortening of myocardial tissue in the region of critical perfusion were determined every 20 minutes. Ileal intramucosal pH and commonly measured cardiovascular variables were determined at the same time points. Myocardial ischemia occurred after 80 minutes of hemodilution, when the mean (±SD) hemoglobin concentration had fallen from a baseline level of 123±18g/L to 82±14g/L (P<.01). From the start of hemodilution to 40 minutes after myocardial ischemia occurred, there were no significant changes in heart rate, cardiac output, oxygen consumption, arterial acid-base balance, or arterial Pco2. Oxygen delivery decreased by approximately 45% (5.99± 1.66 to 3.41±0.90 mL/kg per minute; P<.01) but there were no changes in ileal intramucosal pH (7.31±0.08 to 7.30±0.08; P=.90).

Conclusions:  Myocardium compromised by coronary stenosis is more sensitive to normovolemic hemodilution—induced ischemia than the normally perfused gut mucosa. This limits the potential utilization of the measurement of gastrointestinal intramucosal pH as a guide to tolerable levels of anemia in critically ill patients.Arch Surg. 1997;132:547-552


Sign in

Purchase Options

• Buy this article
• Subscribe to the journal
• Rent this article ?





Also Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
Please click the checkbox indicating that you have read the full article in order to submit your answers.
Your answers have been saved for later.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.


Some tools below are only available to our subscribers or users with an online account.

0 Citations

Sign in

Purchase Options

• Buy this article
• Subscribe to the journal
• Rent this article ?

Related Content

Customize your page view by dragging & repositioning the boxes below.