Noninvasive Blood Pressure Device Research Articles

Spontaneous pneumothorax in early pregnancy: Successful management by thoracoscopy

Spontaneous pneumothorax in early pregnancy: Successful management by thoracoscopy

Assessing hypertension management: the role of 24-hour blood pressure monitoring.

The first fully automatic portable invasive blood pressure recorder was developed 30 years ago. Today, portable noninvasive ambulatory blood pressure devices are capable of measuring blood pressure intermittently for periods of 24 to 48 hours. To discuss the utility of automatic ambulatory blood pressure recording in assessing antihypertensive therapy. Ambulatory blood pressure monitoring is helpful in assessing the pharmacodynamics and the clinical efficacy of antihypertensive drugs. It is superior to office blood pressure measurement in predicting hypertensive end-organ disease. In clinical trials, ambulatory blood pressure monitoring permits a more varied population to enter a study, the number of subjects required is often reduced, and a placebo control group may be unnecessary. The various methods of analyzing ambulatory blood pressure data should be used in a complementary fashion to evaluate antihypertensive drug therapy. We believe that this technique will soon become much more commonly used for hypertension management.

Office Anesthesia Monitoring

SUMMARY It is universally agreed that no electronic device could ever replace human vigilance or knowledge in maintenance of high-quality anesthesia care. Nevertheless, it is accepted practice that all patients be monitored continually when anesthetic agents are employed. The American Society of Anesthesiologists' standards for basic intraoperative monitoring include the presence of qualified anesthesia personnel throughout the conduct of all general anesthetics, regional anesthetics, and monitored anesthesia care and continual evaluation of the patient's oxygenation, ventilation, circulation, and temperature during all anesthetics. The Committee on Anesthesia of the AAOMS has chosen not to dictate monitoring techniques, nor has it chosen to set a “standard of practice” for monitoring.1 The Committee does, however, suggest guidelines that parallel the standards established by the ASA. Surgeons accept monitoring as part of routine office surgery. This monitoring at the very least includes recording of blood pressures, respiratory rate, and heart rate, which at times is more qualitative than quantitative. Today we do not have ideal mechanical monitoring devices but rather devices that accu-rately measure and record a patient's vital functions automatically at brief intervals. Literally hundreds of devices exist in the marketplace, quality and cost spanning a wide range. Required equipment includes (1) noninvasive blood pressure device, (2) ECG and defibrillator, (3) pulse oximeter, and (4) temperature recording device. Coexistent with the use of more sophisticated devices is the necessity to understand how they work and what parameters require intervention. Finally, what will the near future hold? Most likely capnography will be applied to the sedated patient via a nasal prong device to give us a more instantaneous evaluation of hypoventilation. As we advance through the 1990s, standardization will lead to better patient outcomes and probably reductions in malpractice premiums as experienced by anesthesiologists in the 1980s. As has been pointed out in an editorial by Laskin,6 we have a very long and safe history of practicing ambulatory anesthesia in our office surgical practices. We can only expect this to get better.

The relative accuracies of two automated noninvasive arterial pressure measurement devices

We compared the accuracies of two types of noninvasive blood pressure devices. Thirty-two patients requiring an intraarterial catheter for anesthetic management underwent simultaneous monitoring with Dinamap 1846SX and Ohmeda Finapres 3700 devices. For the first 10 minutes of recording, new Dinamap determinations were performed every 60 seconds; subsequent recordings were made at 3-minute intervals. Data were obtained at the time of new Dinamap readings, and twice between new readings to approximate the real-time performance of the two monitors. We defined superior accuracy as a statistically significant difference in mean absolute error greater than 5 mm Hg. With these criteria, pooled data from all patients revealed no difference in performance, even in real time. Pooled data can be misleading since there was a significant amount of variation in accuracy for both monitors. Therefore, we used nonparametric analysis to determine how many individual patients were monitored better by either device. When we compared only data from new Dinamap readings, the Finapres monitor showed superior performance for systolic readings in 13 patients, versus 6 patients for the Dinamap (P less than 0.05, chi-square test). Similar analysis for diastolic and mean pressure performance did not reach statistical significance. However, in real time, the Finapres unit monitored more patients more accurately for systolic (14 Finapres versus 3 Dinamap), diastolic (11 Finapres versus 3 Dinamap), and mean (10 Finapres versus 3 Dinamap) pressure determinations. The magnitude of these differences were, however, less dramatic than expected. This was probably due to stabilization of arterial pressure during the anesthetic, which minimized the error due to intermittent sampling. We conclude that continuous Finapres readings and new Dinamap determinations are equally accurate for diastolic and mean arterial pressures. The accuracy of Finapres appears to be slightly superior for systolic pressure. The intermittent sampling of oscillometric devices compromises their performance relative to the Finapres in many, but not all, cases.

Methods for assessing blood pressure values in humans.

In clinical medicine and epidemiology, measurements of blood pressure largely rely upon the use of cuff inflation and Korotkoff sounds. Although still the most practical, this method has been recognized to have important limitations. This paper focuses on two limitations of the cuff method that have been found while recording 24-hour intraarterial blood pressure in free-living normotensive and hypertensive patients. First, the 24-hour blood pressure is characterized by large long- and short-term variabilities whose magnitudes vary according to the patient's basal blood pressure and age. This is likely to reduce the possibility that a few isolated cuff measurements are accurate and representative of the patient's average blood pressure. Second, during cuff blood pressure assessment by the doctor (and to a lesser degree by the nurse), the patient's blood pressure normally rises due to an alarm reaction, with a large peak within the first 4 minutes and a subsequent decline. The magnitude of the peak rise, as well as its large and unpredictable difference among subjects may be responsible for seriously and variably overestimating the blood pressure. A 10-minute wait from the beginning of the doctor's visit usually avoids this inconvenience. Finally, the paper briefly considers alternative methods to the cuff method, including invasive intraarterial 24-hour recording in ambulatory subjects, which provides a large amount of information but is impractical, and noninvasive automatic blood pressure devices, which offer a promising practical approach but must wait for technical validation.