Comparison of simultaneous invasive and non-invasive measurements of blood pressure based upon MIMIC II database

Comparison of Invasive and Oscillometric Blood Pressure Measurement in Obese and Nonobese Children

BACKGROUND

Obesity and hypertension are public health priorities, with obesity considered to be a potential cause of hypertension. Accurate blood pressure (BP) determination is required and often obtained by automated oscillometric cuff devices. We sought to determine the correlation of oscillometric measurement in children, and if obesity was associated with worse correlation between methods than nonobese children.

METHODS

Retrospective matched case-controlled study of 100 obese (97-99th percentile) and 100 nonobese (25-70th percentile) children after cardiac surgery with simultaneous systolic, diastolic, and mean invasive and oscillometric measurements. Matching was 1:1 for age, sex, race, and Risk Adjustment for Congenital Heart Surgery-1 score. Intraclass correlation coefficients and Bland-Altman plots were used to determine agreement with 0.75 as threshold.

RESULTS

Median age was 13 years (10-15). Agreement was low for systolic (0.65 and 0.61), diastolic (0.68 and 0.61), and mean measurements (0.73 and 0.69) (obese/nonobese). Bland-Altman plots demonstrated oscillometric BP measurements underestimated systolic hypertension (oscillometric readings lower than intra-arterial). Oscillometric measurements underestimated hypotension (systolic oscillometric measurements were higher than intra-arterial). This occurred in obese and nonobese patients. Correlation of oscillometric measurements was similar for nonobese and obese patients.

CONCLUSIONS

In this first ever study of simultaneous BP measurement by oscillometric vs. intra-arterial in obese and nonobese children, correlation is below accepted norms. The correlation of oscillometric cuff measurements is not affected by habitus in children. There is less correlation between oscillometric measurements and intra-arterial measurements during hypertension or hypotension. Healthcare providers should be aware of the limitations of oscillometric measurements.

The incidence of post-intubation hypertension and association with repeated intubation attempts in the emergency department

BACKGROUND

Studies in the non-emergency department (ED) settings have reported the relationships of post-intubation hypertension with poor patient outcomes. While ED-based studies have examined post-intubation hypotension and its sequelae, little is known about, post-intubation hypertension and its risk factors in the ED settings. In this context, we aimed to identify the incidence of post-intubation hypertension in the ED, and to test the hypothesis that repeated intubation attempts are associated with an increased risk of post-intubation hypertension.

METHODS

This study is a secondary analysis of the data from a multicenter prospective observational study of emergency intubations in 15 EDs from 2012 through 2016. The analytic cohort comprised all adult non-cardiac-arrest patients undergoing orotracheal intubation without pre-intubation hypotension. The primary exposure was the repeated intubation attempts, defined as ≥2 laryngoscopic attempts. The outcome was post-intubation hypertension defined as an increase in systolic blood pressure (sBP) of >20% along with a post-intubation sBP of >160 mmHg. To investigate the association of repeated intubation attempts with the risk of post-intubation hypertension, we fit multivariable logistic regression models adjusting for ten potential confounders and patient clustering within the EDs.

RESULTS

Of 3,097 patients, the median age was 69 years, 1,977 (64.0%) were men, and 991 (32.0%) underwent repeated intubation attempts. Post-intubation hypertension was observed in 276 (8.9%). In the unadjusted model, the incidence of post-intubation hypertension did not differ between the patients with single intubation attempt and those with repeated attempts (8.5% versus 9.8%, unadjusted P = 0.24). By contrast, after adjusting for potential confounders and patient clustering in the random-effects model, the patients who underwent repeated intubation attempts had a significantly higher risk of post-intubation hypertension (OR, 1.56; 95% CI, 1.11-2.18; adjusted P = 0.01).

CONCLUSIONS

We found that 8.9% of patients developed post-intubation hypertension, and that repeated intubation attempts were significantly associated with a significantly higher risk of post-intubation hypertension in the ED.

Novel methods of testing and calibration of oscillometric blood pressure monitors

We present a robust method for testing and calibrating the performance of oscillometric non-invasive blood pressure (NIBP) monitors, using an industry standard NIBP simulator to determine the characteristic ratios used, and to explore differences between different devices. Assuming that classical auscultatory sphygmomanometry provides the best approximation to intra-arterial pressure, the results obtained from oscillometric measurements for a range of characteristic ratios are compared against a modified auscultatory method to determine an optimum characteristic ratio, Rs for systolic blood pressure (SBP), which was found to be 0.565. We demonstrate that whilst three Chinese manufactured NIBP monitors we tested used the conventional maximum amplitude algorithm (MAA) with characteristic ratios Rs = 0.4624±0.0303 (Mean±SD) and Rd = 0.6275±0.0222, another three devices manufactured in Germany and Japan either do not implement this standard protocol or used different characteristic ratios. Using a reference database of 304 records from 102 patients, containing both the Korotkoff sounds and the oscillometric waveforms, we showed that none of the devices tested used the optimal value of 0.565 for the characteristic ratio Rs, and as a result, three of the devices tested would underestimate systolic pressure by an average of 4.8mmHg, and three would overestimate the systolic pressure by an average of 6.2 mmHg.

Association of fentanyl use in rapid sequence intubation with post-intubation hypotension

BACKGROUND

The anesthesia literature has reported that pre-intubation fentanyl use is associated with post-intubation hypotension which is a risk factor of poor post-emergency department (ED) prognosis. However, little is known about the relations between fentanyl use for intubation and post-intubation hypotension in the ED. We aimed to determine whether pretreatment with fentanyl was associated with a higher risk of post-intubation hypotension in the ED.

METHODS

We conducted a secondary analysis of data of ED airway management collected from a multicenter prospective study of 14 Japanese EDs from February 2012 through November 2016. We included all adult non-cardiac-arrest patients who underwent rapid sequence intubation for medical indication. Patients were divided into fentanyl and non-fentanyl groups. The primary outcome was post-intubation hypotension (systolic blood pressure ≤90mmHg) in the ED.

RESULTS

Of 1263 eligible patients, 466 (37%) patients underwent pretreatment with fentanyl. The fentanyl group had a higher risk of post-intubation hypotension (17% vs. 6%; unadjusted OR, 1.73; 95%CI, 1.01-2.97; P=0.048) compared to the non-fentanyl group. In the multivariable analysis adjusting for age, sex, weight, principal indication, sedatives, intubator's specialty, number of intubation attempts, and patient clustering within EDs, the fentanyl group had a higher risk of post-intubation hypotension (adjusted OR, 1.87; 95%CI, 1.05-3.34; P=0.03) compared to the non-fentanyl group. In the sensitivity analysis using propensity score matching, this association remained significant (OR, 3.17; 95%CI, 1.96-5.14; P<0.01).

CONCLUSION

In this prospective multicenter study of ED airway management, pretreatment with fentanyl in rapid sequence intubation was associated with higher risks of post-intubation hypotension.

Validation of high temporal resolution spiral phase velocity mapping of temporal patterns of left and right coronary artery blood flow against Doppler guidewire

BACKGROUND

Temporal patterns of coronary blood flow velocity can provide important information on disease state and are currently assessed invasively using a Doppler guidewire. A non-invasive alternative would be beneficial as it would allow study of a wider patient population and serial scanning.

METHODS

A retrospectively-gated breath-hold spiral phase velocity mapping sequence (TR 19 ms) was developed at 3 Tesla. Velocity maps were acquired in 8 proximal right and 15 proximal left coronary arteries of 18 subjects who had previously had a Doppler guidewire study at the time of coronary angiography. Cardiovascular magnetic resonance (CMR) velocity-time curves were processed semi-automatically and compared with corresponding invasive Doppler data.

RESULTS

When corrected for differences in heart rate between the two studies, CMR mean velocity through the cardiac cycle, peak systolic velocity (PSV) and peak diastolic velocity (PDV) were approximately 40 % of the peak Doppler values with a moderate - good linear relationship between the two techniques (R(2): 0.57, 0.64 and 0.79 respectively). CMR values of PDV/PSV showed a strong linear relationship with Doppler values with a slope close to unity (0.89 and 0.90 for right and left arteries respectively). In individual vessels, plots of CMR velocities at all cardiac phases against corresponding Doppler velocities showed a consistent linear relationship between the two with high R(2) values (mean +/-SD: 0.79 +/-.13).

CONCLUSIONS

High temporal resolution breath-hold spiral phase velocity mapping underestimates absolute values of coronary flow velocity but allows accurate assessment of the temporal patterns of blood flow.