0
Clinical Investigations in Critical Care |

The Unidirectional Valve Is the Best Method To Determine Maximal Inspiratory Pressure During Weaning*

Pedro Caruso, MD; Celena Friedrich, RT; Silvia DC Denari, RT; Soraia AL Ruiz, RT; Daniel Deheinzelin, MD, PhD FCCP
Author and Funding Information

*From the Unidade de Terapia Intensiva, Centro de Tratamento e Pesquisa Hospital do Câncer, Hospital AC Camargo, São Paulo, Brazil. Supported by Fundação Antonio Prudente.



Chest. 1999;115(4):1096-1101. doi:10.1378/chest.115.4.1096
Text Size: A A A
Published online

Objectives: Although maximal inspiratory pressure (MIP) is used as an index of inspiratory muscular strength, there is no consensus on how to measure it. We compared, during weaning from mechanical ventilation, two methods of measurement to determine which shows the greater values (MIPbest) and is more reproducible. One method measured MIP when negative pressure was maintained for at least 1 s after a forceful expiration, and the other method measured MIP with a unidirectional expiratory valve (MIPuni).

Design: The study had a crossover design, and patients randomly performed three measurements of each method (t1). The procedure was repeated by the same observer after 20 min (t2). The maximal value in each method was considered.

Setting : ICU, Hospital A.C. Camargo, São Paulo, Brazil.

Patients: Fifty-four consecutive patients undergoing short-term mechanical ventilation who became eligible for the study when their physicians decided to restore spontaneous breathing.

Results: MIPbest values were arrived at using MIPuni 75% of the time either in t1 or t2. MIPuni yielded a higher average of MIPbest values in t1 and t2 (p < 0.0001). The effort-to-effort coefficient of variation of one method compared with the other during t1 and t2 was similar (p > 0.2 for t1; p > 0.8 for t2). Also, when comparing t1 and t2, the coefficients of variation were similar for each method (p > 0.62).

Conclusions: Because MIPuni displayed the maximal values, it is the best method for estimating MIP in patients undergoing short-term mechanical ventilation. The reproducibility of consecutive measurements was similar between the methods, even after a short period of time.

Abbreviations: ANOVA = analysis of variance; MIP = maximal inspiratory pressure; MIPbest = maximal value of inspiratory pressure obtained after three measurements; MIPsta = maximal inspiratory pressure measured when a negative pressure was maintained for at least 1 s after a forceful expiration to residual volume; MIPuni = maximal inspiratory pressure measured with a unidirectional expiratory valve; RV = residual volume.

Figures in this Article

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Figures

Tables

References

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

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

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Related Content

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

Find Similar Articles
CHEST Journal Articles
PubMed Articles
  • CHEST Journal
    Print ISSN: 0012-3692
    Online ISSN: 1931-3543