Predictors Of Hypotension Research Articles

Abstract 3093: Clinical Factors Associated With Hypotension Within 12 Hours Of Antihypertensive Therapy In Ed Stroke Patients

Background: Extremes of blood pressure (BP) have been associated with poor outcomes in acute stroke. Aggressive antihypertensive therapy in stroke patients with elevated blood pressure (BP) can lead to undesired hypotension. We sought to determine whether any pre-treatment factors are associated with undesired hypotension within 12 hours of initiating antihypertensive therapy in emergency department (ED) patients with neurological emergencies. Methods: This was a secondary analysis of an observational study conducted at an urban academic ED and two community EDs between November 2007 and March 2009. Patients with signs or symptoms of neurological emergencies treated with antihypertensives in the ED were eligible for enrollment if they were not enrolled in interventional clinical trials. Demographics, medical history, antihypertensive use, and BP measurements were abstracted in duplicate. Discrepant data were adjudicated by a third investigator. Based on American Heart Association guidelines, target BP was defined as a 20% reduction in systolic BP from that recorded immediately prior to treatment. Hypotension was defined as a systolic BP drop of > 40% from the pre-treatment level or systolic BP <100mmHg within 12hours of initiation of antihypertensives. Univariable Cox regression was used to evaluate factors associated with early hypotension. Results: One hundred patients were enrolled. Median age was 62years (range 36-96), 50 were male and 53 were black. The most common diagnoses were intracerebral hemorrhage (n=36), ischemic stroke (n=35) and hypertensive emergency (n=10). Hypotension occurred in 28 patients within 12hours of initiation of antihypertensive therapy. Median time from first treatment to hypotension was 211 minutes (range 2-629, IQR 98-355). In univariable analysis, lower baseline GCS and higher baseline BP were associated with post-treatment hypotension ( Table ). Conclusions: In this observational study, hypotension occurred frequently in ED patients with neurological emergencies who received antihypertensives. Since sicker patients with higher BP were more likely to become hypotensive, overly aggressive treatment in these patients may have accounted for the hypotension observed. Larger, future studies should see if these patients are indeed treated more aggressively. Table. Univariate predictors of hypotension

Intramuscular Dexmedetomidine Sedation for Pediatric MRI and CT

Although dexmedetomidine has been administered to adults by intramuscular injection for perioperative anxiolysis and sedation, this route in children has not been described, to our knowledge. Our hypothesis was that intramuscular dexmedetomidine can be used to achieve sedation for MRI and CT of children. The quality assurance data on all children who consecutively received intramuscular dexmedetomidine between August 1, 2007, and September 30, 2009, were reviewed. A single or repeated doses of 1-4 αg/kg intramuscular dexmedetomidine had been administered to achieve a minimum Ramsay sedation score of 4. Patient demographics, medical diagnosis, vital signs, adverse events, and outcome measures were reviewed. Sixty-five children received consecutive intramuscular dexmedetomidine injections and successfully completed imaging studies. The MRI group received a total mean of 2.9 αg/kg dexmedetomidine, and the CT group received a mean of 2.4 αg/kg (p ≤ 0.01). There was no statistically significant relation between the total dose of dexmedetomidine received, mean time to achieve sedation (13.1-13.4 minutes), or time to meet discharge criteria after arrival in the recovery unit (17.1-21.9 minutes). Nine patients (14%) experienced hypotension, defined as a decrease in blood pressure to less than 20% of the age-adjusted awake normal value. The dosage of dexmedetomidine was not a predictor of hypotension. None of the patients had bradycardia, hypertension, or oxygen desaturation. The intramuscular route is an alternative approach to dexmedetomidine delivery for pediatric sedation. Larger studies are warranted to evaluate the efficacy, safety, and hemodynamic outcome associated with the intramuscular use of dexmedetomidine in the care of children.

Arterial and plethysmographic waveform variables as predictors of hypotension during hypovolemia in anesthetized patients

s and Programme: EUROANAESTHESIA 2011: The European Anaesthesiology Congress: Clinical and Experimental Circulation

Is it possible to predict hypotension during onset of spinal anesthesia in elderly patients?

Study Objective To evaluate the sensitivity and specificity of various predictors of hypotension during onset of spinal anesthesia in elderly patients. Design Prospective study. Setting 32 ASA physical status I, II, and III patients, aged ≥60 years, scheduled for elective lower limb surgery with spinal anesthesia. Interventions Patients received spinal anesthesia with 10-17.5 mg of bupivacaine. No prophylactic ephedrine or fluid preloading was used. Measurements A 5-minute baseline was recorded and during onset of spinal anesthesia, hemodynamic changes were measured every 10 seconds from the radial artery pressure curve. Data collection ended when patients were ready for surgery, or if ephedrine was given to increase mean arterial pressure. Main Results 21 patients had hypotension. Baseline blood pressure variability low-frequency band power (BPV LF) >8 mmHg 2 and near-infrared spectroscopy (NIRS) reduction ≥5% had high sensitivity (0.73 and 0.90, respectively) and specificity (0.78 and 0.64, respectively), and were significantly associated with the development of hypotension. Conclusions Only NIRS and BPV LF could significantly predict hypotension among the elderly.

Predictors of Hypotension After Induction of General Anesthesia

Hypotension after induction of general anesthesia is a common event. In the current investigation, we sought to identify the predictors of clinically significant hypotension after the induction of general anesthesia. Computerized anesthesia records of 4096 patients undergoing general anesthesia were queried for arterial blood pressure (BP), demographic information, preoperative drug history, and anesthetic induction regimen. The median BP was determined preinduction and for 0-5 and 5-10 min postinduction of anesthesia. Hypotension was defined as either: mean arterial blood pressure (MAP) decrease of >40% and MAP <70 mm Hg or MAP <60 mm Hg. Overall, 9% of patients experienced severe hypotension 0-10 min postinduction of general anesthesia. Hypotension was more prevalent in the second half of the 0-10 min interval after anesthetic induction (P < 0.001). In 2406 patients with retrievable outcome data, prolonged postoperative stay and/or death was more common in patients with versus those without postinduction hypotension (13.3% and 8.6%, respectively, multivariate P < 0.02). Statistically significant multivariate predictors of hypotension 0-10 min after anesthetic induction included: ASA III-V, baseline MAP <70 mm Hg, age > or =50 yr, the use of propofol for induction of anesthesia, and increasing induction dosage of fentanyl. Smaller doses of propofol, etomidate, and thiopental were not associated with less hypotension. To avoid severe hypotension, alternatives to propofol anesthetic induction (e.g., etomidate) should be considered in patients older than 50 yr of age with ASA physical status > or =3. We conclude that it is advisable to avoid propofol induction in patients who present with baseline MAP <70 mm Hg.

Fast Fourier Transforms as Prophecy

Fast Fourier Transforms as Prophecy

Using Heart Rate Variability to Stratify Risk of Obstetric Patients Undergoing Spinal Anesthesia

In this study, we evaluated whether point correlation dimension (PD2), a measure of heart rate variability, can predict hypotension accompanying spinal anesthesia for cesarean delivery. After the administration of spinal anesthesia with bupivacaine, hypotension was defined as systolic blood pressure </=75% of baseline within 20 min of intrathecal injection. Using the median prespinal PD2 (3.90) to form 2 groups, LO and HI, all 11 hypotensive patients were in the LO group, and all 11 patients without hypotension were in the HI group. Baseline heart rate in the LO group was 95 bpm (10.2 sd), versus 81 bpm (9.6 sd) in the HI group. PD2 shows promise as a predictor of hypotension in pregnant women receiving spinal anesthesia.

The incidence and risk factors for hypotension after spinal anesthesia induction: an analysis with automated data collection.

We sought to identify factors that are associated with hypotension after the induction of spinal anesthesia (SpA) by using an anesthesia information management system. Hypotension was defined as a decrease of mean arterial blood pressure of more than 30% within a 10-min interval, and relevance was defined as a therapeutic intervention with fluids or pressors within 20 min. From January 1, 1997, to August 5, 2000, data sets from 3315 patients receiving SpA were recorded on-line by using the automatic anesthesia record keeping system NarkoData. Hypotension meeting the predefined criteria occurred in 166 (5.4%) patients. Twenty-nine patient-, surgery-, and anesthesia-related variables were studied by using univariate analysis for a possible association with the occurrence of hypotension after SpA. Logistic regression with a forward stepwise algorithm was performed to identify independent variables (P < 0.05). The discriminative power of the logistic regression model was checked with a receiver operating characteristic curve. Calibration was tested with the Hosmer-Lemeshow goodness-of-fit test. The univariate analysis identified the following variables to be associated with hypotension after SpA: age, weight, height, body mass index, amount of plain bupivacaine 0.5% used for SpA, amount of colloid infusion before puncture, chronic alcohol consumption, ASA physical status, history of hypertension, urgency of surgery, surgical department, sensory block height of anesthesia, and frequency of puncture. In the multivariate analysis, independent factors for relevant hypotension after SpA consisted of three patient-related variables ("chronic alcohol consumption," odds ratio [OR] = 3.05; "history of hypertension," OR = 2.21; and the metric variable "body mass index," OR = 1.08) and two anesthesia-related variables ("sensory block height," OR = 2.32; and "urgency of surgery," OR = 2.84). The area of 0.68 (95% confidence interval, 0.63-0.72) below the receiver operating characteristic curve was significantly greater than 0.5 (P < 0.01). The goodness-of-fit test showed a good calibration of the model (H = 4.3, df = 7, P = 0.7; C = 7.3, df = 8, P = 0.51). This study contributes to the identification of patients with a high risk for hypotension after SpA induction, with the risk increasing two- or threefold with each additional risk factor. By using automated data collection, 5 (chronic alcohol consumption, history of hypertension, body mass index, sensory block height, and urgency of surgery) of 29 variables could be detected as having an association with hypotension after spinal anesthesia induction. The knowledge of these risk factors should be useful in increasing vigilance in those patients most at risk for hypotension, in allowing a more timely therapeutic intervention, or even in suggesting the use of alternative methods of spinal anesthesia, such as titrated continuous or small-dose spinal anesthesia.

Advance prediction of hypotension at cesarean delivery under spinal anesthesia

Cardiovascular responses to supine inferior vena cava compression might predict hypotension risk during elective cesarean delivery using spinal anesthesia. In this pilot study we investigated 27 women before operation by taking blood pressure and heart rate measurements for 5 min in the left lateral position, 5 min supine, and then performed one further reading in the left lateral position and one sitting. Anesthesia with hyperbaric bupivacaine was rigorously standardised. A pre-operative ‘supine stress test’, combining an increase in maternal heart rate of greater than 10 beats/min or leg flexion movements while supine, was analysed. A positive supine stress test (SST) was 4.1 times more frequent in those with severe systolic hypotension below 70% of baseline (12 out of 16 women) than in those without (2 out of 11 women), with a sensitivity of 75% (95% C.I. 48% to 93%) and specificity of 82% (95% C.I. 48% to 98%). A positive test was associated with twice as much vasopressor use as a negative test ( 30.7± 14.5 mg versus 13.5± 9.9 mg; P = 0.0014). Unlike the SST, cardiovascular responses to the change from recumbent to sitting (tilt test) were not useful as a predictor of hypotension.