Comparison of continuous pH-meter and intermittent pH paper monitoring of gastric pH in critically ill children

Accuracy of pH strip testing and pH liquid testing versus standard pH meter of gastric contents in critically ill patients: a diagnostic accuracy study

OBJECTIVE

The utilisation of pH level measurements from gastric contents may indicate the preferred tip position of a nasogastric tube or monitor the efficacy of stress ulcer prophylaxis in critically ill patients. We aimed to determine the accuracy of pH strip (pHS) tests and pH liquid (pHL) tests compared with the standard pH meter (pHM).

DESIGN

Diagnostic accuracy study.

SETTING

Gastric contents from medically critically ill patients.

PARTICIPANTS

In total, 113 gastric samples were collected from 27 critically ill patients.

OUTCOME MEASURE

The level of pH measured by pHM, pHS and pHL.

RESULTS

The pH values measured by pHM, pHS and pHL were 5.83 (IQR 5.12-6.61), 5.50 (IQR 5.00-6.00) and 5.75 (IQR 5.25-6.25), respectively. The pHS test showed greater accuracy, exhibiting a more positive correlation with the standard pHM measurement than the pHL test, with Y=0.95*X+0.56; rho=0.91, p<0.001, and Y=1.09*X - 0.72; rho=0.75, p<0.001, respectively. However, the pHS test demonstrated less agreement with the pHM than the pHL test, with biases of -0.27 versus 0.18, respectively. Noticeably, a slight variation in pHL from the standard pH values was found when we measured gastric contents with a pH lower than 5.

CONCLUSION

Both the pHS and pHL methods were good options for measuring gastric pH in critically ill patients. However, it was advisable to find alternative approaches to the pHL testing method when anticipated gastric acidity levels fall below 5.

TRIAL REGISTRATION NUMBER

TCTR20220530004.

Pharmacokinetic and pharmacodynamic effects of 2 registered omeprazole preparations and varying dose rates in horses

Background

Omeprazole preparations vary in bioavailability in horses.

Hypothesis/Objectives

To characterize the pharmacokinetics and pharmacodynamics of an existing enteric‐coated oral omeprazole paste (REF) and a novel, in‐feed, enteric‐coated dry granule preparation (NOV).

Animals

Twelve Standardbred/Thoroughbred mares free from clinical disease.

Methods

A prospective, blinded randomized interventional study was trial, conducted in 3 parts: (a) bioavailability study, (b) dose titration study, and (c) comparative clinical pharmacodynamic study, each using a blocked crossover design.

Results

Consistent with the larger dose administered, Cmax (median, 1032 ng/mL; range, 576‐1766) and AUC0‐24 (median, 63.9 μg/mL*min; range, 42.4‐152.4) were greater after single oral administration of NOV than REF (282.7 ng/mL; range, 94.8‐390.2, and 319 23.8 μg/mL*min; range, 8.2‐42.3, respectively; both P = .004). No differences were observed between products for absolute oral bioavailability (NOV 55% range, 15‐88; REF 17% range, 10‐77; P = .25). Treatment with both preparations was associated with reduced gastric squamous ulcer scores and increased pH of gastric fluid. Bioequivalence was demonstrated for pharmacodynamic measures with the exception of % time pH <4, despite differences in dose rate and subsequent plasma omeprazole concentrations.

Conclusions and Clinical Importance

The findings of this study indicate that the NOV product would be a suitable alternative to the reference product, and confirm that plasma concentrations of omeprazole and omeprazole dose do not predict drug pharmacodynamics in horses.

Effect of pH Test-Strip Characteristics on Accuracy of Readings

BACKGROUND

Little is known about characteristics of colorimetric pH test strips that are most likely to be associated with accurate interpretations in clinical situations.

OBJECTIVES

To compare the accuracy of 4 pH test strips with varying characteristics (ie, multiple vs single colorimetric squares per calibration, and differing calibration units [1.0 vs 0.5]).

METHODS

A convenience sample of 100 upper-level nursing students with normal color vision was recruited to evaluate the accuracy of the test strips. Six buffer solutions (pH range, 3.0 to 6.0) were used during the testing procedure. Each of the 100 participants performed 20 pH tests in random order, providing a total of 2000 readings. The sensitivity and specificity of each test strip was computed. In addition, the degree to which the test strips under- or overestimated the pH values was analyzed using descriptive statistics.

RESULTS

Our criterion for correct readings was an exact match with the pH buffer solution being evaluated. Although none of the test strips evaluated in our study was 100% accurate at all of the measured pH values, those with multiple squares per pH calibration were clearly superior overall to those with a single test square.

CONCLUSIONS

Test strips with multiple squares per calibration were associated with greater overall accuracy than test strips with a single square per calibration. However, because variable degrees of error were observed in all of the test strips, use of a pH meter is recommended when precise readings are crucial.

Aspirin is associated with low oral pH levels and antacid helps to increase oral pH

Objective

Aspirin is a commonly used medicine for primary and secondary prevention of cardiovascular diseases. It is an acidic medicine associated with gastric irritation and acid reflux, which in turn can lead to low oral pH levels. Therefore, it is important to understand the association between aspirin and oral pH levels in order to achieve an optimum oral health condition among patients who take aspirin on prescription.

Results

Out of 373 patients, 162 (44%) were males and 245 (66%) were on aspirin. 71% of aspirin taking patients and 29% of non-aspirin taking patients had oral pH less than 6.5 (P < 0.01). Aspirin showed a significant association with low oral pH levels (odds ratio = 1.91, 95% CI 1.23–2.99, P < 0.01). 78 patients were given antacids and followed up for 4 weeks, 63 of them (81%) showed an improvement in oral pH and the improvement was marked in the group who had oral pH between 5.5–6.0 compared to the group who had oral pH between 6.0–6.5 (P = 0.03). The results show that aspirin therapy is associated with low oral pH and administration of an antacid with aspirin helps to increase the oral pH level.

0.5 mg/kg versus 1 mg/kg of intravenous omeprazole for the prophylaxis of gastrointestinal bleeding in critically ill children: a randomized study

OBJECTIVE

To compare the effect of 2 doses of intravenous omeprazole on gastric pH, gastrointestinal bleeding, and adverse effects in critically ill children.

STUDY DESIGN

We undertook a prospective randomized clinical trial in critically ill children at risk of gastrointestinal bleeding. The effect of 2 intravenous omeprazole regimens (0.5 or 1 mg/kg every 12 hours) on the gastric pH and incidence of gastrointestinal hemorrhage was compared. The efficacy criteria were a gastric pH >4 and the absence of clinically significant gastrointestinal bleeding.

RESULTS

Forty patients, 20 in each treatment group, were studied. Overall, the gastric pH was greater than 4 for 57.8% of the time, with no difference between the doses (P = .66). The percentage of time with a gastric pH > 4 increased during the study (47.8% between 0 and 24 hours vs 76% between 24 and 48 hours, P = .001); the greater dose showed a greater increase in the percentage of time with a pH > 4: between hours 24 and 48 of the study, the gastric pH was greater than 4 for 84.5% of the time with the 1 mg/kg dose and for 65.5% of the time with the 0.5 mg/kg dose (P = .036). Plasma omeprazole levels were greater with 1 mg/kg dose, but no correlation was found between omeprazole plasma levels and gastric pH. No toxic adverse effects were detected, and there was no clinically significant bleeding.

CONCLUSION

Neither of the 2 omeprazole regimens achieved adequate alkalinization of the gastric pH during the first 24 hours. Between 24 and 48 hours, the 1 mg/kg dose maintained the gastric pH greater than 4 for a greater percentage of the time.