Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TONOMETRY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2000

[Impression and applanation tonometry in irregular corneas. Comparison with intraocular needle tonometry].

PURPOSE: During the past 4 years we have demonstrated in eyes with corneal pathology that applanation tonometry (Goldmann, Perkins) generally delivers falsely low measurements in comparison to intraocular needle tonometry. The aim of this study was to evaluate whether impression tonometry (Schioetz) is more precise than applanation tonometry in determining the intraocular pressure in eyes with corneal disorders. PATIENTS AND METHODS: In 75 eyes with suspected glaucoma and various corneal disorders, we performed applanation tonometry and impression tonometry before intraocular needle tonometry. Applanation tonometry was repeated after impression tonometry to unveil a possible tonography effect. Intraocular needle tonometry was performed thereafter. RESULTS: Applanation tonometry results were 4.1 +/- 5.3 mmHg below intraocular pressure as determined by intraocular needle tonometry. Impression tonometry results were also lower: 4.3 +/- 6.8 mmHg (5.5 g), 4.3 +/- 6.4 mmHg (7.5 g), and 4.8 +/- 7.0 mmHg (10.0 g). The differences between applanation tonometry and impression tonometry were statistically not significant. In contrast, all the differences between extraocular tonometry procedures and intraocular needle tonometry were statistically highly significant (P < 0.001). CONCLUSION: In corneal pathology both, applanation tonometry and impression tonometry do not deliver reliable results on an average. Only intraocular needle-tonometry delivers reliable results in these eyes.

Corneal Diseases↗
PubMed2000

Comparison of the response of saline tonometry and an automated gas tonometry device to a change in CO2.

OBJECTIVE: To examine the speed of response of saline tonometry and an automated gas tonometry system by using standard tonometry catheters. DESIGN: In vitro validation study. SETTING: Experimental research laboratory. INTERVENTIONS: Tonometry catheters were placed in a test chamber designed to simulate the lumen of a hollow viscus and were exposed to a rapid change in CO2 from 0% to 5% or 10%. Measured CO2 over time was fit to a mathematical model to determine the response time constant (the time to reach 63% of the final value) for each system. MEASUREMENTS AND MAIN RESULTS: Response time to a change in CO2 was significantly faster with the automated gas system than with traditional saline tonometry. The mathematical time constant for a 5% change in CO2 in a gas environment was 2.8 mins (95% confidence interval, 2.6-3.0 mins) for the gas and 6.3 mins (95% confidence interval, 5.8-7.3 mins) for the saline technique. These times were longer for the CO2 change in a liquid environment: The time constant was 4.6 mins (95% confidence interval, 4.5-4.7 mins) for the gas system and 7.8 mins (95% confidence interval, 7.15-8.6 mins) for the saline tonometry. There was a significantly lower final equilibration value for the CO2 measurement with saline tonometry. There was essentially no difference in time constants for each system for a 5% change compared with a 10% CO2 change, except for a slightly faster time constant for the gas tonometry system with a 5% change in the gas environment (5%: 2.8 mins vs. 10%: 3.3 mins). CONCLUSIONS: The automated gas tonometry system has a significantly faster response to a change in CO2 than conventional saline tonometry.

Carbon Dioxide↗
PubMed1998

Comparison of air tonometry with gastric tonometry using saline and other equilibrating fluids: an in vivo and in vitro study.

OBJECTIVE: 1) To compare saline gastric tonometry monitoring with air tonometry (Tonocap) in a group of general ICU patients. 2) An in vitro investigation of the performance of other fluids used in gastric tonometry and to assess the effects of variation of temperature and carbon dioxide concentration within the range encountered in clinical use. DESIGN: a) A prospective, observational study in ICU patients b) A comparative laboratory study. SETTING: The general Intensive Care Unit (ICU) and the laboratory at Leeds General Infirmary. PATIENTS AND PARTICIPANTS: Nine patients in the general ICU with severe sepsis or septic shock. MEASUREMENTS AND RESULTS: In vivo comparison of saline and air tonometry demonstrated a difference between the two techniques. Bland & Altman analysis showed a mean bias in the measurement of gastric PCO2 of 1.88 kPa with a precision of 1.22 kPa, with saline giving the lower result. In vitro, saline, air (Tonocap), gelatin and heparinised blood were used, at temperatures of 33-42 degrees C and at carbon dioxide concentrations of 4-8 kPa. While gelatin and blood gave unpredictable results, dependent on temperature and carbon dioxide concentration, air tonometry gave highly reproducible results. A consistent bias between the results with saline and air tonometry was seen over the range of temperatures and carbon dioxide (CO2) concentrations studied. The mean bias was 0.85 kPa with a precision of 0.40 kPa, saline consistently giving lower results. CONCLUSIONS: There are clinically significant differences in values for gastric mucosal PCO2 measured by air tonometry and saline tonometry both in vivo and in vitro.

Acidosis↗
PubMed1998

Intraocular pressure difference in Goldmann applanation tonometry versus Perkins hand-held applanation tonometry in overweight patients.

OBJECTIVE: To analyze the increase in intraocular pressure (IOP) caused by anatomic and physiologic factors in overweight patients when using Goldmann applanation tonometry. DESIGN: A prospective cohort study. PARTICIPANTS: Seventy average-weight individuals who had no difficulties with IOP measurements at the slit lamp and 12 obese patients with suspected glaucoma who could position the head at the slit lamp only with great effort participated. INTERVENTION: The authors compared IOP values between slit-lamp-mounted Goldmann applanation tonometry and Perkins hand-held tonometry. MAIN OUTCOME MEASURE: The difference in Goldmann and Perkins IOP measurements was examined. RESULTS: In the group of obese patients, the mean IOP was 20.9+/-2.28 mmHg (mean +/- standard deviation; range, 18-26 mmHg) for the right eye and 21.4+/-3.16 mmHg (range, 16-28 mmHg) for the left eye when determined by Goldmann tonometry and 16.3+/-2.39 mmHg (range, 13-20 mmHg) for the right eye and 16.3+/-2.42 (range, 11-19 mmHg) for the left eye when determined by Perkins tonometry. The mean decrease was 4.5+/-1.3 mmHg (range, 3-7 mmHg) for the right eye and 4.9+/-1.9 mmHg (range, 2-9 mmHg) for the left eye. In the control group, the mean difference between the two types of tonometers for the right eye was 0.34+/-0.69 mmHg and for the left eye was 0.33+/-0.82 mmHg. Patients who had a falsely elevated IOP on Goldmann tonometry had an average body mass index of 34+/-3.82 (range, 28.5-41.9); most were female (5:1 ratio). CONCLUSION: The authors believe simultaneous breath-holding and thorax compression, with subsequent increase in venous pressure, may be a causative factor for transitory elevations of IOP. Perkins tonometry in obese patients may help avoid a false diagnosis of glaucoma caused by transitory elevations in IOP.

Adult↗
PubMed2001

Ocuton-S self tonometry vs. Goldmann tonometry; a diurnal comparison study.

PURPOSE: To compare 24-hour diurnal intraocular pressure (IOP) measurements obtained using the Ocuton-S applanation self tonometer and the Goldmann tonometer. METHODS: 24-hour diurnal IOP curves were obtained on 14 eyes of 7 trained patients suffering from medically controlled primary open angle glaucoma. IOP was measured every third hour starting at 9 a.m. with a calibrated Goldmann tonometer; one week later, a similar set of measurements was obtained with Ocuton-S self tonometry by the patients. One week later still, ultrasound corneal pachymetry was performed at the same hours. RESULTS: Overall IOP (24-hour mean) did not differ significantly between the different measuring techniques (ANOVA, p = 0.74), but the IOP differed in a statistically significant manner around the clock (ANOVA, p = 0.00006). The mean Goldmann tonometric readings were up to 2.8 mmHg lower than the Ocuton-S values during the daytime (9 a.m. to 9 p.m.), however, during the night (12 midnight to 6 a.m.) mean IOP measured with Goldmann tonometry was 2.2 to 3.3 mmHg higher than the corresponding average of the self tonometry readings. There was a statistically significant interaction between the type of tonometry and the time of the measurement (p = 0.0007). Central corneal thickness (CCT) showed a significant change during the 24-hour period (p = 0.000001). CONCLUSION: IOP shows a different diurnal curve when measured with the Goldmann tonometer and with the Ocuton-S applanation self tonometer. The instruments' readings might be influenced in different ways by the diurnal changes of the corneal thickness. Since Ocuton-S self tonometry underestimates the IOP in the early morning period, a careful evaluation is necessary when nocturnal and early morning IOP elevation is investigated with this technique.

Adult↗
PubMed1998

Gastric tonometry: in vivo comparison of saline and air tonometry in patients with cardiogenic shock.

Measurement of gastric intramucosal pH (pHi) has been advocated to assess gastric perfusion. Regional PCO2 (rPCO2) values are measured using saline tonometry (rsPCO2) and more recently using air tonometry (raPCO2). We compared 237 measurements of saline and air tonometry in 19 consecutive, severely ill patients (mean age 59 (range 31-76) yr, 19 males, APACHE II 22 +/- 7) with cardiogenic shock. Equilibration period was set to 90 min. Nineteen independent paired samples of mean raPCO2 and mean rsPCO2 of each patient showed good correlation (r = 0.93, P < 0.001). Mean raPCO2 was 6.5 (1.8) kPa and mean rsPCO2 6.8 (2.4) kPa. PCO2 measured by saline was significantly higher than that measured by air (P < 0.05). Bland and Altman analysis showed a bias (mean rsPCO2-mean raPCO2) of 0.3 kPa and a precision of 1.2 kPa. Agreement between the two methods decreased with increasing rPCO2 concentrations. Although air tonometry of rPCO2 is a promising technique, a systematic disagreement with saline tonometry at high rPCO2 values requires further investigation and cautious interpretation of these values.

Adult↗
PubMed1993

[Principles of measurements in tonometry at the time of Albrecht von Graefes to D2 mission and self-tonometry].

There is no doubt that an elevation of intraocular pressure (IOP) precedes any morphological or functional glaucomatous damage for years, if not decades. Surprisingly, in the present glaucoma literature methods for a quantification of such a damage are prevailing. There might be two reasons for this: The question of tonometry is supposed to be perfectly and definitely solved or tonometry as the most significant diagnostic tool for an early diagnosis of glaucoma has been lost out of sight. Two aspects shall be discussed in the following: Firstly, we want to deal with an improved glaucoma management especially in the early phase of the disease. The question is when and how often should tonometry be performed to detect the typically greater diurnal fluctuations of IOP in glaucoma. This has already been pointed out in particular by Sampaolesi and Hager. Secondly, the technique of the most appropriate tonometer for this purpose is outlined. Important aspects are the accuracy of the instrument according to the standard set by the Goldmann applanatation tonometer as well as safety and easy handling. Like in other branches of medicine where the patient is more and more involved in his own disease control (eg self-measurement of blood pressure in patients with arterial hypertension), self-tonometry is likely to become a revolutionary step towards an improved management and follow-up of glaucoma. These are the objectives we should concentrate on. Technical solutions, clinical applications and experiences are demonstrated.

Circadian Rhythm↗
PubMed1996

Comparison of gastric air tonometry with standard saline tonometry.

OBJECTIVE: To compare partial pressure of carbon dioxide (PCO2) measurements obtained by sampling gastric intraluminal air with those obtained by standard saline tonometry. DESIGN: Prospective, unblinded study. SETTING: Intensive care unit in a tertiary cardiac surgical center. PATIENTS: 20 patients undergoing cardiac surgery. INTERVENTIONS: Gastric tonometric catheters were inserted, gastric fluid was aspirated, and 100 cc of air was injected into the stomach. MEASUREMENTS: After an equilibration period of 30 min, samples of gastric air and saline were anaerobically aspirated and analyzed on a standard blood gas machine. The reproducibility of PCO2 measurements in a given patient was assessed by analyzing consecutive samples of gastric air and calculating the coefficient of variation (CV). RESULTS: PCO2 values measured in samples of gastric air (PCO2 air) were highly correlated with those derived by saline tonometry (PCO2ss)(r2 = 0.95, p = 0.0001); PCO2 air was significantly greater than PCO2ss (50 +/- 17 vs 48 +/- 17 mmHg, p = 0.0001). Intramucosal pH (pHi) calculated from PCO2 air was significantly lower than that calculated from PCO2ss (7.26 +/- 0.23 vs 7.28 +/- 0.24, p = 0.0001). Analysis of intermethod differences showed significant bias for both PCO2 (2.4 +/- 7.6 mmHg, mean +/- 2SD, bias +/- precision) and pHi ( -0.023 +/- 0.074, mean +/- 2SD, bias +/- precision). The within-subject variability of replicate PCO2 measurements in gastric air was low (CV = 2.6 +/- 0.8). CONCLUSION: We conclude that intraluminal PCO2 can be accurately determined in postoperative cardiac surgery patients by instilling air into the stomach and analyzing samples of gastric air on a standard blood gas machine, In comparison with saline tonometry, air tonometry consistently yields lower pHi values.

Aged↗
PubMed1988

Oculab Tono-Pen, Goldmann applanation tonometry, and pneumatic tonometry for intraocular pressure assessment in gas-filled eyes.

We performed 84 intraocular pressure measurements with the Oculab Tono-Pen, Goldmann applanation tonometer, and pneumatic tonometer in 47 eyes that had undergone pars plana vitrectomy and gas-fluid exchange. Measurements made by using the Tono-Pen were accurate when compared to those made by Goldmann tonometry (mean difference, 0.74 mm Hg). In a subset of eyes with increased intraocular pressure (greater than or equal to 25 mm Hg), the Tono-Pen provided measurements similar to those made by Goldmann applanation tonometry (P greater than .60), with only three of 39 readings (8%) underestimating the Goldmann pressure by more than 3 mm Hg. Pneumatic tonometry significantly underestimated the intraocular pressure in eyes with increased pressure (P less than .001), with 20 of 39 readings (51%) underestimating the Goldmann pressure by 5 mm Hg or more.

Evaluation Studies as Topic↗
PubMed1993

Tonometry in the general practice setting (I): Tono-Pen compared to Goldman applanation tonometry.

Intraocular pressure was measured in 132 consecutive patients over the age of 20 in a general practice with two general practitioners (GP). Tono-Pen tonometry was compared to Goldmann applantation tonometry in a masked, randomized design. Also, agreement between Tono-Pen measurements by the GPs and the ophthalmologist was estimated. Both mean difference between Tono-Pen and Goldmann applantation measurements and mean differences between Tono-Pen readings made by GPs and ophthalmologist were less than 1 mmHg. Ninety-five percent limits of agreement between the two methods were approximately -4.5 mmHg and 5.5 mmHg, and between observers approximately -4 mmHg and 5 mmHg. The Tono-Pen was agreeable both to patients and physicians. The GPs made as accurate measurements as the ophthalmologist. The wide limits of agreement are clinically much more important than the small differences between means. Random variation was much greater than systematic variation. Wide limits of agreement will apply to all known methods of clinical tonometry.

Adult↗
PubMed2003

The evaluation of tonometry and self-tonometry with Ocuton tonometers.

BACKGROUND: The purpose of the present study was to evaluate the clinical applicability of the Ocuton-A and Ocuton-S applanation tonometers, and to compare their use and accuracy parameters to those of Goldmann applanation tonometry (GAT). MATERIAL/METHODS: In the first study, intraocular pressure (IOP) was measured with an Ocuton-A tonometer, followed by another measurement using GAT in 15 subjects (30 eyes). Ocuton-tonometry was performed on three occasions separated by three-minute intervals. In Study 2 the impact of increased patient familiarity on measurement accuracy using the self-tonometer was investigated in 5 subjects (10 eyes) by comparing two consecutive series of five Ocuton-S measurements. In Study 3 nine trained volunteers measured their own IOP with an Ocuton-S self-tonometer after GAT and Ocuton-A measurements by an experienced investigator. RESULTS: Study 1 showed that the measured IOP value was significantly higher using the Ocuton-A tonometer, compared to values obtained using GAT. In Study 2 we found that increased practice in self-tonometry did not alter measurement accuracy. In Study 3 the difference between IOP readings obtained with the Ocuton-S and Ocuton-A instruments was not significant. CONCLUSIONS: The portable Ocuton-A tonometer may become a useful instrument for IOP measurement by professional workers outside the clinic. Qualified patients are able to use the Ocuton-S self-tonometer reliably even after limited training, and its measurement accuracy is acceptable for IOP monitoring. Both the Ocuton A and S devices consistently overestimate the IOP by approximately 2 mm Hg compared to the corresponding Goldmann readings.

Aged↗
PubMed1999

Self-tonometry with the Ocuton S versus Goldmann tonometry.

BACKGROUND: The purpose of the study was to evaluate the acceptance and reproducibility of a new self-tonometer (Ocuton S) and to compare it with the Goldmann applanation tonometer. METHODS: The Ocuton S was studied in 20 healthy volunteers and 100 patients. After detailed explanation to each individual and a number of test measurements, we studied the reproducibility and accuracy of the Ocuton S in 20 healthy volunteers with and without topical anaesthesia. Acceptance was graded by means of visual analogue scales. Each volunteer had to measure his/her own IOP in three consecutive measurements. The data were compared with Goldmann tonometry at random times. One hundred patients were introduced to the Ocuton S. Either three consecutive self-measurements of IOP were performed and then compared with three consecutive measurements by Goldmann tonometry, or vice versa. This was done randomly. RESULTS: Forty-one of 100 patients were unable to perform three consecutive measurements with the Ocuton S after at least 15 min introduction time to the device (non-success). Fifty-nine of 100 patients were able to measure their IOP with the Ocuton S. The mean pressure value with the Ocuton S was 23.2+/-8.2 mmHg, compared with Goldmann 18. 4+/-5.7 mmHg. The difference of 5+/-5.7 mmHg was statistically significant (paired t-test p<0.01). The visual analogue scale scores of healthy volunteers (100 mm = maximal comfort, 0 mm = not acceptable), was 72+/-31 in anaesthetised eyes and 39+/-41 mm without anaesthesia. CONCLUSION: The Ocuton S seems to be an acceptable means for the majority of patients of measuring their IOP at home. Refinement of the accuracy of the device seems necessary.

Adult↗
PubMed1990

Airpuff tonometry versus applanation tonometry.

In order to study the reliability of airpuff tonometry, 230 eyes of 115 patients had their IOP measured with 2 airpuff tonometers, NCT and Pulsair, and one applanation tonometer, Perkins handheld Goldmann Type, between Dec 87 and March 89. Each patient had three readings per eye with each airpuff instrument and two readings per eye with the Perkins instrument. Mean age for the group was 68 +/- 11 (SD), range 36-87 years. The mean values were for Perkins: 21.21 +/- 6.27 R.E., 21.28 +/- 5.67 L.E.; for NCT: 21.11 +/- 6.95 R.E., 21.27 +/- 5.41 L.E.; for Pulsair: 23.05 +/- 6.00 R.E., 23.76 +/- 5.39 L.E. The ranges were for Perkins: 9-45 R.E., 9-38 L.E.; for NCT: 8-59 R.E., 11-38 L.E.; for Pulsair: 9-52 R.E., 11-38 L.E. For the Pulsair a value of 18 was found to be a cut-off point below which there were no false negatives, and for the NCT this value was found to be 17. A linear relation between airpuff and applanation tonometry was found, but also a large spread, both for false positives and false negatives.

Adult↗
PubMed1991

[Relevance of ocular pressure tonometry and classical tonometry with reference to prognosis in suspected glaucoma and ocular hypertension].

A total of 44 eyes of patients with suspected glaucoma or ocular hypertension were examined both by ocular pressure tonometry (OPT) according to Ulrich and by tonography according to Leydhecker. The visual fields of these eyes were prospectively followed up for 3 years to compare the prognostic value of the two methods. In 30 of the 44 eyes a worsening visual field loss was observed, while in 14 the visual fields showed no change. Much better correlation was noted between values obtained by OPT and changes in visual field than between values obtained by tonography and visual field loss. Conventional tonography yielded 39% of false-negative values, but only 11% were recorded with OPT. Therefore, according to results of these and further investigations, OPT appears to be a more helpful and reliable method for assessment and decisions on therapy in patients with suspected glaucoma or ocular hypertension.

Humans↗
PubMed1998

Small bowel tonometry is more accurate than gastric tonometry in detecting gut ischemia.

Gastric tonometer PCO2 measurement may help identify gut ischemia in critically ill patients but is frequently associated with large measurement errors. We tested the hypothesis that small bowel tonometer PCO2 measurement yields more accurate information. In 10 anesthetized, mechanically ventilated pigs subject to progressive hemorrhage, we measured gut oxygen delivery and consumption. We also measured tonometer PCO2 minus arterial PCO2 (DeltaPCO2) and calculated the corresponding intracellular pH from tonometers placed in the stomach and jejunum. We found that the correlation coefficient (r2) for biphasic gut oxygen delivery-DeltaPCO2 relationships was 0.29 +/- 0.52 for the gastric tonometer vs. 0.76 +/- 0.25 for the small bowel tonometer (P < 0.05). In addition, the critical gastric tonometer DeltaPCO2 was excessively high and variable (62.9 +/- 39.6) compared with the critical small bowel tonometer DeltaPCO2 (17.0 +/- 15.0, P < 0.01). Small bowel tonometer PCO2 was closely correlated with superior mesenteric vein PCO2 (r2 = 0.81, P < 0.001), whereas gastric tonometer PCO2 was not (r2 = -0.13, P = not significant). We conclude that measurement of gastric tonometer PCO2 yields excessively noisy and inaccurate data on the onset of gut anaerobic metabolism in hemorrhagic shock. Small bowel tonometer PCO2 is less noisy and, as a result, is superior in detecting gut hypoperfusion and the onset of anaerobic metabolism.

Animals↗