CI: Monitoring Criteria: Patient Positioning (2006)

Torres A, Serra-Batlles J, Ros E, et al. Pulmonary aspiratin of gastric contents in patients receiving mechanical ventilation: The effect of body position. Ann Int Med 1992; 116: 540-543. PubMed ID: 1543307
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To determine if the semirecumbent position (45-degree angle) decreases aspiration of gastric contents to the airways in intubated and mechanically ventilated patients.

Inclusion Criteria:
  • Respiratory ICU
  • Patients require mechanical ventilation and nasogastric intubation
Exclusion Criteria:

None listed

Description of Study Protocol:
  • Randomized  2-period crossover trial
  • Study each patient at supine and 45° semirecumbent position in random order 48 hrs apart with goal body position attained and continued 12 hr prior to study
  • Baseline gastric, esophageal, bronchial, and blood samples
  • Instill 37 megabecquerels of Tc99 sulfur colloid via NGT
  • Sample gastric, pharyngeal, bronchial, and blood every hour for 5 hours
  • Count radioisotope content of samples by scintigraphy, corrected for decay and express as log10 of cpm
  • Assay gastric, pharyngeal, and bronchial samples for microbiological cultures at baseline and 48 hr
Data Collection Summary:
  • Endotracheal tube pressures
  • Scintigraphic data
  • Microbiological data
Description of Actual Data Sample:

19 patients, 13 men, mean age 60 years

Summary of Results:
  • Scintigraphy
    • Baseline samples not different for any parameter
    • Endobronchial aspirates had greater radioactivity with supine position, p=0.036.
    • Radioactivity ­ for both positions, but supine was 298 at 30 min and 2592 cpm at 300 min, p=0.013, while semirecumbent was 103 at 30 min and 216 at 300 min, p=0.04.
    • The effect of time in position on aspiration was greater with supine position, p=0.05.
  • Microbiological data
    • 120 microorganisms isolated from 76 gastric speciment; 116 from 76 endotracheal aspirates; and 68 from 38 pharyngeal samples.
    • 41% and 36% of microorganisms isolated in gastric cultures were also isolated in endotracheal and pharyngeal samples.
    • In semirecumbent position, 32% of same organism was seen in all 3 samples sites vs 68% with supine
    • 3 patients developed pneumonia 3,4 and 7 days after testing, and 2/3 had same microorganism isolated in lungs as was seen in gastric, pharyngeal and endobronchial samples. The third had the same microorganism in endobronchial and pharyngeal but not gastric samples.
Author Conclusion:

The supine position and length of time the patient is kept in this position are potential risk factors for aspiration of gastric contents. Elevating the head of the bed for patients who can tolerate the semirecumbent position may be a simple, no-cost prophylactic measure.

Funding Source:
University/Hospital: FIS-Fondo de Investigacion Sanitaria, CIRIT-Comisio Interdepartamental per a la Recerca I Tecnologia (Spain)
Reviewer Comments:

Selection bias not clear, but using patient as own control helps.

No description of patient acuity- would Spanish ICU patients in 1992 correspond to US ICU patients today?

Blinding to position not possible, but randomized crossover of same patients

Detailed description of procedures

Reliable outcome measures.

Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.3. Were the target population and setting specified? N/A
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? N/A
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
3. Were study groups comparable? No
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? No
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? N/A
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? No
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? N/A
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A