Servo-plethysmo-manometry for continuous noninvasive blood pressure monitoring

Servoplethysmomanometry (Penáz method) is based on the principle of "vascular unloading" or "arterial volume clamp". It permits continuous recording of the arterial pressure pulse in a finger. We evaluated such a device (Finapres) intraoperatively in cardiac surgical patients and compared the results with those obtained using simultaneous intra-arterial pressure recording. METHODS. Intravenous anesthesia was employed in a total of 31 patients. Invasive pressure monitoring was carried out in the radial artery. The cuff of the Finapres was wrapped around the 3rd finger, either on the same side as the radial cannula (group I, n = 15) or on the contralateral side (group II, n = 16). Quantitative comparison was accomplished for the paired values obtained by the two methods by calculating linear regression equations and correlation coefficients (r), as well as for the differences between the paired values (means, SD, frequency distributions). RESULTS. In group I (ipsilateral recording), r was 0.74 for systolic (SAP), 0.52 for diastolic (DAP), and 0.77 for mean (MAP) pressure. The means +/- SD of the differences (mm Hg) were -1.6 +/- 16.6 (SAP), 4.6 +/- 11.5 (DAP), and 0.2 +/- 11.3 (MAP). In group II (contralateral recording), r was found to be 0.86 (SAP), 0.72 (DAP), and 0.82 (MAP). The mean differences were -2.7 +/- 13.1 (SAP), 4.7 +/- 9.8 (DAP), and -2.6 +/- 10.9 mm Hg (MAP). Prior to cardiopulmonary bypass (CPB) the results of the two methods corresponded to a higher degree than after CPB; during CPB the MAP values correlated poorly in the two groups (r = 0.62). DISCUSSION. The results obtained may be interpreted to mean that the Finapres will enable us to monitor arterial blood pressure continuously with satisfactory reliability when the cuff design has been improved.     

Continuous noninvasive blood pressure monitoring during thoracic surgery.

To evaluate the usefulness of noninvasive blood pressure monitoring during thoracic surgery, blood pressure measurements obtained with the Finapres 2300 (Ohmeda, Boulder, CO) were compared with an intraarterial catheter system in 10 patients undergoing thoracotomy for lobectomy or pneumonectomy. The Finapres measurements were compared with pressure data obtained ipsilaterally from a radial artery catheter-transducer system. The waveforms were recorded using a strip chart recorder; the systolic (SBP) and diastolic blood pressures (DBP) were measured every 20 seconds on the paper trace. Precision and bias were calculated for SBP and DBP for each patient and for the pooled data, with the invasive blood pressure being considered the gold standard. A total of 1,861 measurement pairs were recorded, 938 pairs during one-lung ventilation. The Finapres underestimated SBP during two-lung ventilation, and overestimated SBP during one-lung ventilation. The precision was good and the biases were small, but there were wide individual variations. It is concluded that the Finapres can be useful in estimating the variability and following the trends of radial arterial blood pressure during thoracic surgery, and is an acceptable alternative to invasive blood pressure monitoring.     

An evaluation of the T-Line Tensymeter continuous noninvasive blood pressure device during induced hypotension

A new continuous noninvasive blood pressure measurement device, the T-Line Tensymeter TL100 (Tensys Medical Inc., San Diego, CA, USA) which enables avoidance of arterial cannulation has been developed. We compared the values obtained using the T-Line values to simultaneous arterial line measurements in patients undergoing general anaesthesia with induced hypotension. Twenty-five patients, aged 18-70 years, were studied. The T-Line and arterial line were positioned on the contralateral wrists. Intra-operative, real-time, blood pressure data were electronically captured and stored on a computer. Bland-Altman plots and 95% limits of agreement show that the majority of T-Line data points were within 5 mmHg of the arterial line measurements (67%) and agreement was within 15 mmHg in 94.6% or more of all measurements. There was virtually no distinguishable error over the course of surgery using the device. In conclusion, the T-Line measurements correlate with arterial measurements during anaesthesia in which there were periods of both normotensive and hypotensive anaesthesia. The T-Line Tensymeter represents a noninvasive alternative to an arterial line in cases when arterial blood sampling is not required.     

连续无创血压监测系统在产科麻醉的应用

目的探讨连续无创血压监测系统(CNAP)CNAP~(TM)monitor 500比较传统的无创袖带血压(NIBP)监测系统应用于腰硬联合麻醉后剖宫产监测低血压发生的时效性。方法选择85例产妇在腰硬联合麻醉下行剖宫产术。总共有1040对产妇的收缩压和舒张压被监测,间隔周期为3 min,观察时间为麻醉前到胎儿娩出后,并记录新生儿的脐静脉血气分析和Apgar评分。结果相比NIBP,每一周期CNAP能监测的最低收缩压平均值(103±20.6 mmHg)明显低于(P0.05)NIBP的平均值(116±17.9 mmHg)和最高的CNAP收缩压平均值(120±19.6 mmHg)。低血压定义为收缩压低于90 mmHg,CNAP监测组低血压的发生率70.58%,而NIBP监测组低血压的发生率为35.29%。当CNAP监测的低血压(收缩压为90 mmHg)时,未发现胎儿酸中毒(脐静脉血p H值7.25)。结论 CNAP能够比NIBP监测出更多的低血压事件,而且动脉血压明显低于NIBP监测系统。从胎儿利益的角度出发,CNAP的监测比NIBP更适于需要腰硬联合的产科手术。     

全麻术后患者持续有创动脉压监测并发症的预防及护理

对370例全麻术后患者实施持续有创动脉压监测,均选择桡动脉穿刺置管,无一例发生并发症。提出严格掌握桡动脉穿刺适应证,选择合适的穿刺针及穿刺部位,严密观察,及时处理,严格掌握留置针留置时间,可提高动脉穿刺置管的成功率,保证持续动脉有创压监测的有效性,减少并发症。     

Wireless continuous arterial blood pressure monitoring during surgery: a pilot study

Patient monitoring devices supporting wireless transmission can facilitate transport and ambulation of patients in hospitals. To replace wired sensors with wireless sensors, the accuracy and resistance to interference of the wireless sensors have to be documented. We compared the performance of a wireless arterial blood pressure biomedical sensor prototype with standard wired sensors in a clinical setting. Four patients undergoing laparoscopic abdominal surgery were recruited for testing of the device. Lines to a wireless arterial blood pressure sensor and standard wired sensor were connected to the same arterial cannula inserted in the right radial artery. Data from both systems were logged for postprocedure statistical comparison. During the procedure, 13 other electric devices were used, either continuously or intermittently. A sample-by-sample comparison was performed for both wired and wireless data. Statistical tests showed mean difference of 0.71, standard deviation of 0.14, and confidence interval of -1.28 to 1.56), indicating no significant electromagnetic interference on invasive arterial blood pressure monitoring caused by biomedical devices used during surgery. The wireless pressure biomedical sensor with Bluetooth wireless transmission of signals did not interfere with biomedical devices used in the operating room or vice versa.     

Acute dermal capillary rupture associated with noninvasive blood pressure monitoring

We report a case of Rumpel-Leede phenomenon, or acute dermis capillary rupture, secondary to noninvasive blood pressure monitoring in a patient with type 2 diabetes mellitus. The most likely cause was increased venous pressure during cycling of the blood pressure cuff during a hypertensive state. Anesthesiologists need to be aware that acute dermal capillary rupture, although rare, can occur in patients with thrombocytopenia and/or long-standing diabetes.     

Continuous noninvasive finger blood pressure during controlled hypotension. A comparison with intraarterial pressure

The Finapres is a noninvasive monitor that continuously displays the arterial waveform, pulse rate, and systolic, mean, and diastolic blood pressure. We determined its bias (mean prediction error) and precision (mean absolute error), relative to directly measured radial arterial blood pressure, in 16 otherwise healthy patients undergoing spinal fusion surgery under hypotensive anesthetic techniques. Data were recorded during three contiguous epochs: 20 min of normotension; 30 min following the initiation of hypotension; 20 min of hypotension. The Finapres demonstrated a systolic, mean, and diastolic bias (+/- standard deviation) of 3.6 +/- 12.3, 5.2 +/- 10.8, and 8.3 +/- 9.4 mmHg, respectively. There were no significant differences in systolic bias among the epochs, whereas mean and diastolic bias were both greater during the hypotensive epoch, compared to the normotensive epoch. In 2 of the 16 patients, systolic and mean arterial pressure bias exceeded 20 mmHg. Finapres precisions of systolic, mean, and diastolic blood pressures were 9.8 +/- 9.0, 8.7 +/- 7.6, and 10.4 +/- 8.2 mmHg, respectively. Precisions among the epochs were not significantly different. When Finapres pressures were "corrected" by subtracting the baseline difference between Finapres and oscillometrically determined mean pressure, bias decreased significantly. The correction process did not improve precision. The Finapres closely tracked changes in blood pressure, even in the presence of a large bias. In most patients, the Finapres is a useful continuous noninvasive blood pressure monitor. Periodic calibration of the Finapres by the difference between Finapres and oscillometrically determined mean arterial pressure is recommended.     

全身麻醉中连续无创动脉血压监测与有创动脉血压监测的比较

目的 评价麻醉期间TL-300系统测得的连续无创血压(continuous non-invasive arterial pressure,CNAP)和有创血压(invasive arterial pressure,IAP)监测的一致性和安全性.方法 择期全身麻醉手术患者72例,麻醉诱导前将动脉导管置入非优势手的桡动脉内行IAP监测,另一侧手臂连接TL-300系统行CNAP监测,记录IAP及相应时间点CNAP,以及相关的并发症.结果 CNAP与IAP所测SBP、DBP和MAP偏倚分别为(-0.6±7.0)、(-7.8±9.8)和(-5.8±6.2)mmHg(1 mmHg=0.133kPa),一致性界限分别为-14.6～13.4 mmHg、-27.4～11.8 mmHg、-18.2～6.6 mmHg,在其相应的一致性界限范围内所占比值分别为95.2％、96.1％和94.9％.两种BP监测方法的SBP、DBP和MAP的相关系数r分别为0.927、0.711和0.903 (P＜0.01).均未发生肢体缺血、坏死、感觉异常.结论 TL-300CNAP和IAP比较,有较高的相关性和一致性,提供无创实时连续、准确的BP监测,可安全用于全身麻醉手术患者.     

Arterial pressure and neurologic morbidity during carotid surgery under peridural anesthesia

In 163 carotid reconstructions under peridural anesthesia performed from 1988 to 1991, we routinely measured residual systemic and carotid artery pressure during clamping. Seventy-nine patients (48.5%) were asymptomatic and 84 (51.5%) had a history of neurologic manifestations in the form of transient ischemic attacks (28%) or stroke (13.5%). None of the patients died perioperatively. Eight patients (4.9%) had strokes, with complete recovery in five. A shunt was placed in 22 patients (13.5%) because of neurologic evidence that carotid clamping was poorly tolerated. This study showed a distinct association between residual pressure in the internal carotid artery and systemic arterial pressure and intraoperative neurologic morbidity. Using a cutoff value of 35 mm Hg for residual pressure, the sensitivity was 77% and specificity 81%. Using a cutoff of 80 mm Hg, the sensitivity was 60% and specificity 86%. There was no correlation between mean systemic arterial pressure and residual carotid artery pressure. The use of a shunt was the only factor with predictive value for postoperative neurologic complications. These findings suggest that measurement of systemic arterial pressure and residual carotid artery pressure is useful during carotid surgery, but further study is needed before this information can be extrapolated to carotid surgery under general anesthesia.     

Accuracy of the CNAP monitor,a noninvasive continuous blood pressure device,in providing beat-to-beat blood pressure readings in the prone position

Study ObjectiveTo assess the accuracy of a noninvasive continuous arterial pressure (CNAP) monitor in patients who are positioned prone in the operating room.DesignProspective study.SettingOperating room at a children's hospital.Patients20 pediatric patients, aged 13.8 ± 2 years, and weight 63.7 ± 18.8 kg, scheduled for surgery in the prone position, and for which arterial catheter placement was planned.InterventionsMeasurements were recorded with an arterial line (AL) and a new noninvasive continuous blood pressure (BP) monitor.MeasurementsSystolic (SBP), diastolic (DBP), and mean arterial (MAP) pressure readings were captured from an arterial cannula and the CNAP device every minute during anesthesia.Main ResultsThe study cohort consisted of analysis of 4104 pairs of SBP, DBP, and MAP values, which showed an absolute difference between the AL and CNAP device readings of 7.9 ± 6.3 mmHg for SBP, 5.3 ± 4.3 mmHg for DBP, and 4.6 ± 3.9 mmHg for MAP. Bland-Altman analysis of MAP values showed a bias of 0.26 mmHg, with upper and lower limits of agreement of 12.18 mmHg and -11.67 mmHg, respectively. CNAP readings deviated from arterial values by ≤ 5 mmHg in 67% of MAP values, 59% of DBP values, and 43% of SBP readings. The difference was ≤ 10 mmHg for 94% of MAP readings, 90% of DBP values, and 73% of SBP readings.ConclusionsDuring prone positioning, the CNAP monitor provided clinically acceptable accuracy for MAP values, similar to those reported in adults in the supine position.