Heart Rate Variability Predicts Severe Hypotension after Spinal Anesthesia

Background: Hypotension due to vasodilatation after spinal anesthesia (SA) may be harmful. Heart rate variability, an indirect measure of autonomic control, may predict hypotension.

Methods: One hundred patients were studied. Retrospectively, heart rate variability was analyzed in 30 patients, classified depending on the lowest systolic blood pressure (SBP) after SA. Seventy patients were studied prospectively, assigned to one of two groups by their low to high frequency ratio (LF/HF) before SA. Sensitivity and specificity of LF/HF for prediction of decrease of SBP greater 20% of baseline were tested.

Results: Retrospective analysis showed differences of LF/HF depending on the degree of hypotension after SA. Prospective analysis demonstrated significant differences of SBP after SA depending on baseline LF/HF (mean +/- SD): low LF/HF (1.3 +/- 0.7) = > SBP: 91 +/- 8% of baseline versus high LF/HF (5.5 +/- 2.4) = > SBP: 66 +/- 10% of baseline (P < 0.05). Baseline LF/HF as well as high frequency and proportional decrease of SBP after SA correlated significantly, in contrast to baseline hemodynamic parameters heart rate and SBP. A receiver operator curve characteristic analysis showed a sensitivity and specificity of LF/HF > 2.5 of 85% to predict SBP decrease of greater than 20% of baseline after SA.     

Heart Rate Variability Predicts Severe Hypotension after Spinal Anesthesia for Elective Cesarean Delivery

Background: Hypotension due to vasodilation during subarachnoid block (SAB) for elective cesarean delivery may be harmful. Heart rate variability (HRV), reflecting autonomic control, may identify patients at risk of hypotension.

Methods: Retrospectively, HRV was analyzed in 41 patients who were classified into one of three groups depending on the decrease in systolic blood pressure (SBP): mild (SBP > 100 mmHg), moderate (100 > SBP > 80 mmHg), or severe (SBP < 80 mmHg). Prospectively, HRV and hemodynamic data of 19 patients were studied. Relative low frequency (LF), relative high frequency (HF), and LF/HF ratio were analyzed.

Results: Retrospective analysis of HRV showed a significantly higher sympathetic and lower parasympathetic drive in the groups with moderate and severe compared with mild hypotension before SAB (median, 25th/75th percentiles): LF/HF: mild: 1.2 (0.9/1.8), moderate: 2.8 (1.8/4.6), P < 0.05 versus mild; severe: 2.7 (2.0/3.5), P < 0.05 versus mild. Results were confirmed by findings of LF and HF. Prospectively, patients were grouped according to LF/HF before SAB: low-LF/HF: 1.5 (1.1/2.0) versus high-LF/HF: 4.0 (2.8/4.7), P < 0.05; low-LF: 58 +/- 9% versus high-LF: 75 +/- 10%, P < 0.05; low-HF: 41 +/- 10% versus high-HF: 25 +/- 10%, P < 0.05. High-risk patients had a significantly lower SBP after SAB (76 +/- 21 vs. 111 +/- 12 mmHg; P < 0.05).     

Substitution of cysteine for phenylalanine 751 in mature von Willebrand factor is a novel candidate mutation in a family with type IIA von Willebrand disease

Summary Type IIA is a variant form of von Willebrand disease (vWD) characterized by the absence of von Willebrand factor (vWF) high molecular weight multimers in plasma. Most of the candidate missense mutations potentially responsible for type IIA vWD have been found clustered within a short segment of vWF, lying between Gly⁷⁴² and Glu⁸⁷⁵ of the mature subunit. The present work reports a single heterozygous T → G transversion in eight patients from a large type IIA vWD family, resulting in the substitution Phe⁷⁵¹→Cys. The absence of this mutation in 100 normal vWF genes as well as the lack, in these patients, of any other abnormality within the whole exon 28 encoding amino acids 463–921 of mature vWF, provide a strong support that this non-conservative mutation may be at the origin of the disease in this family. The presence of an additional cysteine at position 751 may induce a conformational change of the vWF subunit affecting either its ' in vivo ' sensitivity to proteolytic cleavage or, more likely, its intracellular transport as suggested by the abnormal multimeric pattern of platelet vWF observed in these patients.     

Neuroendocrine stress response and heart rate variability: a comparison of total intravenous versus balanced anesthesia

Attenuating intraoperative stress is a key factor in improving outcome. We compared neuroendocrine changes and heart rate variability (HRV) during balanced anesthesia (BAL) versus total IV anesthesia (TIVA). Forty-three patients randomly received either BAL (sevoflurane/remifentanil) or TIVA (propofol/remifentanil). Depth of anesthesia was monitored by bispectral index. Stress hormones were measured at 7 time points (P1 = baseline; P2 = tracheal intubation; P3 = skin incision; P4 = maximum operative trauma; P5 = end of surgery; P6 = tracheal extubation; P7 = 15 min after tracheal extubation). HRV was analyzed by power spectrum analysis: very low frequency (VLF), low frequency (LF), high frequency (HF), LF/HF ratio, and total power (TP). LF/HF was higher in TIVA at P6 and TP was higher in TIVA at P3-7 (P3: 412.6 versus 94.2; P4: 266.7 versus 114.6; P5: 290.3 versus 111.9; P6: 1523.7 versus 658.1; P7: 1225.6 versus 342.6 ms2)). BAL showed higher levels of epinephrine (P7: 100.5 versus 54 pg/mL), norepinephrine (P3: 221 versus 119.5; P4: 194 versus 130.5 pg/mL), adrenocorticotropic hormone (P2 10.5 versus 7.7; P5: 5.3 versus 3.6; P6: 10.9 versus 5.3; P7: 20.5 versus 7.1 pg/mL) and cortisol (P7: 6.9 versus 3.9 microg/dL). This indicates a higher sympathetic outflow using BAL versus TIVA during ear-nose-throat surgery.     

Overlapping induction of anesthesia: an analysis of benefits and costs

BACKGROUND: Overlapping induction (OI), i.e., induction of anesthesia with an additional team while the previous patient is still in the operating room (OR), was investigated. METHODS: The study period was 60 days in two followed by three ORs during surgical Block Time (7:30 am until 3:00 pm). Patients were admitted the day before surgery and were thus available and did not have surgery that day unless there was a time reduction. Facilities were already constructed. Number of cases, Nonsurgical Time (Skin Suture Finish until next Procedure Start Time), Turnover Time, and Anesthesia Control Time plus Turnover Time were studied. In addition, economic benefit was calculated. RESULTS: Three hundred thirty-five cases were studied. Using OI, the time of care of regularly scheduled cases was shortened, and the number of cases performed within OR Block Time increased (151 to 184 cases; P < 0.05). Nonsurgical Time (in h:min) decreased (1:08 +/- 0:26 to 0:57 +/- 0:18; P < 0.001), Turnover Time decreased (0:38 +/- 0:24 to 0:25 +/- 0:15; P < 0.05), and Anesthesia Control Time plus Turnover Time decreased (0:43 +/- 0:23 to 0:28 +/- 0:18; P < 0.001). Subgroup analysis showed a significant benefit of OI only in three ORs. In three ORs, economic benefit can be gained at a case mix index greater than 0.3 besides additional costs. CONCLUSIONS: Overlapping induction increased productivity and profit despite the expense of additional staff. Subgroup analysis emphasizes the importance of the number of ORs involved in OI.     

Effect of xenon anaesthesia on accuracy of cardiac output measurement using partial CO2 rebreathing

Cardiac output (CO) determination based on partial CO(2) rebreathing has recently been introduced into clinical practice. The determination of flow is crucial for exact CO readings and the physical properties of xenon, i.e. high density and viscosity, may influence flow readings. This study compared echocardiography-derived CO measurements with the partial rebreathing method during total intravenous (TIVA) vs. xenon-based anaesthesia. Thirty-nine patients ASA physical status III undergoing aortic reconstruction were randomly assigned to receive either xenon (Xe, n = 20) or TIVA (T, n = 19) based general anaesthetic. Paired measurements were taken before xenon administration, after xenon administration, before and after clamping of the abdominal aorta and after declamping and at corresponding time points in the TIVA group. Data were analysed with a Bland-Altmann plot. Bias and precision were acceptable and comparable before xenon administration (T 0.54 +/- 0.92 l.min(-1) vs. Xe 0.11 +/- 1.1 l.min(-1)), but after xenon administration CO was largely overestimated by partial CO(2) rebreathing (T 0.04 +/- 0.91 l.min(-1) vs. Xe -4.0 +/- 2.1 l.min(-1)). In the TIVA group, bias and precision after declamping increased significantly (P < 0.01) compared to all time points except baseline. In its current application, the NICO cardiac output monitor appears to be inappropriate for determination of CO during xenon based anaesthesia.     

Prevalence and Predictors of Video Game Addiction: A Study Based on a National Representative Sample of Gamers

Video gaming has become a popular leisure activity in many parts of the world, and an increasing number of empirical studies examine the small minority that appears to develop problems as a result of excessive gaming. This study investigated prevalence rates and predictors of video game addiction in a sample of gamers, randomly selected from the National Population Registry of Norway (N?=?3389). Results showed there were 1.4 % addicted gamers, 7.3 % problem gamers, 3.9 % engaged gamers, and 87.4 % normal gamers. Gender (being male) and age group (being young) were positively associated with addicted-, problem-, and engaged gamers. Place of birth (Africa, Asia, South- and Middle America) were positively associated with addicted- and problem gamers. Video game addiction was negatively associated with conscientiousness and positively associated with neuroticism. Poor psychosomatic health was positively associated with problem- and engaged gaming. These factors provide insight into the field of video game addiction, and may help to provide guidance as to how individuals that are at risk of becoming addicted gamers can be identified.     

A comparison of the i-gel™ with the LMA-Unique™ in non-paralysed anaesthetised adult patients

This study assessed two disposable devices; the newly developed supraglottic airway device i-gel™ and the LMA-Unique™ in routine clinical practice. Eighty patients (ASA 1–3) undergoing minor routine gynaecologic surgery were randomly allocated to have an i-gel ( n  = 40) or LMA-Unique ( n  = 40) inserted. Oxygen saturation, end-tidal carbon dioxide, tidal volume and peak airway pressure were recorded, as well as time of insertion, airway leak pressure, postoperative sore-throat, dysphonia and dysphagia for each device. Time of insertion was comparable with the i-gel and LMA-Unique. There was no failure in the i-gel group and one failure in the LMA-Unique group. Ventilation and oxygenation were similar between devices. Mean airway pressure was comparable with both devices, whereas airway leak pressure was significantly higher (p < 0.0001) in the i-gel group (mean 29 cmH₂O, range 24–40) compared with the LMA-Unique group (mean 18 cmH₂O, range 6–30). Fibreoptic score of the position of the devices was significantly better in the i-gel group. Post-operative sore-throat and dysphagia were comparable with both devices. Both devices appeared to be simple alternatives to secure the airway. Significantly higher airway leak pressure suggests that the i-gel may be advantageous in this respect.     

Predictive value of D-dimer assay in superficial thrombophlebitis of the lower limbs

Objective

The negative predictive value of D-dimer (DD) assay in patients with venous thromboembolic disease is well established for deep vein thrombosis and pulmonary embolism. Little is known about the value of DD assay in patients with superficial thrombophlebitis (ST). The purpose of this study was to assess the value of DD assay in patients with ST of the lower limb.

Method

The study group was composed of 100 consecutive patients, irrespective of age. Patients with clinical manifestations suggestive of ST of the lower limbs with positive duplex color Doppler evidence confirming the diagnosis and DD assay results (Vidas D-Dimer Exclusion) within 24 hours were included in the study. Patients with thrombosis in another site in addition to the superficial vein of the lower limb, those taking anticoagulants for more than 48 hours, and those with a condition known to potentially elevate DD levels were excluded. The volume of the thrombus was determined echographically and reported as mean diameter and length.

Results

Sixty-two women and 38 men were included. Mean age (± 5) was 58 years ± 13.48 (range 18–90; median: 57). The ST involved the Great saphenous (n = 74), the small saphenous (n = 11) or another vein (n = 15). Mean thrombus volume was 4453 mm³ ± 7101 (range 94–38484; median: 1751). Mean DD level was 829 ng/ml ± 516.72 (range 100–2567; median: 715.5). DD assay was negative (< 500 ng/ml) in 32 patients (32%) and positive in 68 (68%). For these three items, there was no significant difference between ST with and without varicose veins. DD assay was always positive (≥ 500 ng/ml) in all patients aged over 70 years (n = 22). In patients aged less than 70 years (n = 78), DD assay was positive in 46 (59%) and negative in 32 (41%). DD level was positively correlated with thrombus volume in patients aged less than 70 years (P < 0.0001). ROC analysis, sensitivity as a function of specificity by thrombus volume for the entire population, determined the usefulness of a negative DD assay. Considering the critical threshold at 5914 mm³, sensitivity was 1.0 (95CI 0.89–1.0), with 0.29 specificity (95CI 0.19–0.42), 1.00 negative predictive value and 0.75 positive predictive value. However, the thrombus volume was less than this threshold value in three of the nine cases of ST with extension to the terminal portion of the saphenous.

Conclusion

A positive DD assay was observed in 68% of patients with ST, with no significant difference with or without varicose veins. The test was positive in all patients aged over 70 years and in 59% of those aged under 70 years. There was a correlation between DD level and thrombus volume, yielding a threshold volume (5914 m³) above which all DD tests were positive. Nevertheless, this threshold volume was too great to include all ST extending to the terminal portion of the saphenous. Measurement of DD level is thus not contributive to the diagnosis of ST.     

Changes in heart rate variability may reflect sympatholysis during spinal anaesthesia

Background: To investigate if changes in low-to-high frequency ratio (LF/HF), low frequency (LF) and high frequency (HF) heart rate variability reflect autonomic regulation during spinal anaesthesia (SA) in pregnant women scheduled for elective Caesarean section. Methods: Prospective clinical trial. Systolic blood pressure (SBP) and heart rate variability were analysed at baseline, 5 min after SA and 15 min after SA. Patients were assigned by baseline LF/HF. Group LF/HF < 2.5 (n= 52) was compared to group LF/HF > 2.5 (n= 48). Non-parametric tests for statistical analysis. Results: Group LF/HF > 2.5 showed a significant decrease in LF/HF and LF as well as an increase in HF during SA (median, range): baseline LF/HF [4.0 (3.2/4.8)] decreased to 2.3 (1.3/3.4) at event 15 min after SA (P < 0.001). Baseline LF = 59(43/71)% decreased to 40 (27/55)% at event 15 min after SA (P < 0.05). Baseline HF = 15(13/22)% increased to 26(15/41)% at event 15 min after SA (P < 0.05). In contrast, group LF/HF < 2.5 demonstrated only moderate changes in LF/HF, LF and HF during SA. SBP decreased significantly in group LF/HF > 2.5 (median and range) lowest SBP group LF/HF > 2.5: 80 (50/127 mmHg vs. group LF/HF < 2.5: 109 (104/142) mmHg, P < 0.001. Decrease of SBP before and after SA was correlated with a decrease in LF/HF, LF, and HF, respectively: LF/HF - SBP: r= 0.30, r(2)= 0.09, P < 0.001; LF - SBP: r= 0.25, r(2)= 0.06, P < 0.05, HF, NS. Conclusions: Changes in heart rate variability parameters in the course of SA may reflect a decrease in sympathetic activity and relative increase in parasympathetic activity as a result of the block. In the course of SA, the more pronounced the changes in heart rate variability were the more distinct the hypotension.