The effect of nicardipine on the surgical pleth index during thyroidectomy under general anesthesia: A prospective double-blind randomized controlled trial.

BACKGROUND: The effectiveness of surgical pleth index (SPI) for managing nociception-antinociception balance during general anesthesia with vasodilators, including nicardipine has not been demonstrated. We aimed to compare the time course during surgery in SPI values in patients receiving nicardipine or remifentanil infusion during thyroidectomy. METHODS: Forty patients undergoing thyroidectomy were randomly assigned to receive nicardipine (group N; n = 19) or remifentanil (group R; n = 21) along with induction (propofol, fentanyl, and rocuronium) and maintenance (50% desflurane/nitrous oxide in oxygen) anesthesia (goal bispectral index [BIS] ∼50). The infusion of nicardipine or remifentanil was started before the 1st incision and adjusted to keep mean blood pressure (MBP) within ±20% of the preoperative value. SPI, BIS, end-tidal desflurane concentration (EtDes), MBP, and heart rate were recorded at 2.5 minute intervals from the 1st incision to the end of surgery. Extubation and recovery times, pain score/rescue ketorolac consumption, and adverse events in postanesthesia care unit (PACU) were recorded. RESULTS: The trend of SPI during surgery was comparable between the 2 groups (P = 0.804), although the heart rates in group N were significantly higher than those in group R (P = 0.040). The patient characteristics, trends of BIS, EtDes, and MBP during surgery, extubation and recovery times, and incidence of nausea/vomiting were comparable between the groups. Group N had significantly lower pain scores and rescue ketorolac consumption at PACU. CONCLUSION: SPI was comparable between patients receiving nicardipine or remifentanil infusion during thyroidectomy under general anesthesia, which suggests that the administration of nicardipine may confound the interpretation of SPI values during general anesthesia. CLINICAL TRIAL REGISTRATION: This trial was registered in the UMIN clinical trials registry (unique trial number: UMIN000019058; registration number: R000022028; principal investigator's name: Young Ju Won; date of registration: September 17, 2015).

Analysis of plethysmographic waveform changes induced by beach chair positioning under general anesthesia.

During shoulder surgery, patients typically are placed in the beach chair position. In rare cases, this positioning has resulted in devastating outcomes of postoperative cerebral ischemia (Cullen and Kirby in APSF Newsl 22(2):25-27, 2007; Munis in APSF Newsl 22(4):82-83, 2008). This study presents a method to noninvasively and continuously hemodynamically monitor patients during beach chair positioning by using the photoplethysmograph signal recorded from a commercial pulse oximeter. Twenty-nine adults undergoing shoulder surgery were monitored before and after beach chair positioning with electrocardiogram, intermittent blood pressure, end tidal carbon dioxide, and photoplethysmograph via Nellcor finger pulse oximeter. Fast Fourier transform (FFT) was used to perform frequency-domain analysis on the photoplethysmograph (PPG) signal for data segments taken 80-120 s before and after beach chair positioning. The amplitude density of respiration-associated PPG oscillations was quantified measuring the height of the FFT peak at respiratory frequency. Results were reported as (median, interquartile range) and statistical analysis was performed using Wilcoxon sign rank test. Data were also collected when vasoactive drugs phenylephrine and ephedrine were used to maintain acceptable mean arterial pressure during a case. With beach chair positioning, all subjects who did not receive vasoactive drugs showed an increase in the FFT amplitude density of respiration-associated PPG oscillations (p < 0.0001) without change in pulse-associated PPG oscillations. The PPG was more accurate at monitoring the change to beach chair position than blood pressure or heart rate. With vasoactive drugs, pulse-associated PPG oscillations decreased only with phenylephrine while respiration-associated oscillations did not change. Frequency domain analysis of the PPG signal may be a better tool than traditional noninvasive hemodynamic parameters at monitoring patients during beach chair position surgery.

Cardiovascular responses to different stages of restorative dental treatment unaffected by local anaesthetic type.

BACKGROUND: The aim of this study was to evaluate the cardiovascular effects of maxillary infiltration using 2% lidocaine with 1:100,000 adrenaline, 4% articaine with 1:200,000 adrenaline, and 4% articaine with 1:100,000 adrenaline in different stages during restorative dental procedures. METHODS: Twenty healthy patients randomly received 1.8 mL of the three local anaesthetics. Systolic blood pressure, average blood pressure, diastolic blood pressure, and heart rate were evaluated by the oscillometric and photoplethysmograph methods in seven stages during the appointment. RESULTS: Statistical analysis by ANOVA and Tukey tests of cardiovascular parameters did not show significant differences between the anaesthetic associations. There were significant differences for the parameters among different clinical stages. CONCLUSIONS: The variation of cardiovascular parameters was similar for lidocaine and articaine with both adrenaline concentrations and showed no advantage of one drug over the other. Cardiovascular parameters were influenced by the stages of the dental procedures, which showed the effect of anxiety during restorative dental treatment.

Characteristic alteration in the second derivative of photoplethysmogram in children.

BACKGROUND: The second derivative of the photoplethysmogram (SDPTG) has been verified as a useful method for analyzing pulse wave form in adults; however, there have been few studies on the SDPTG in children. METHODS: We examined age-related alteration of SDPTG (study 1) and the SDPTG response to a vasodilator (study 2). The subjects in study 1 were 36 healthy children aged 0.9-16.0 years. The subjects in study 2 were 13 children aged 5.4-18.9 years with a history of Kawasaki disease. Subjects received an i.v. infusion of 0.568 mg/kg dipyridamole. We assessed the SDPTG by d/a ratio, b/a ratio and aging index (AGI). RESULTS: The d/a ratio increased with advance of age (r= 0.636, P < 0.001), and the b/a ratio and AGI decreased with advance of age (r=-0.343, P < 0.05 and r=-0.678, P < 0.001, respectively). The d/a ratio and AGI were correlated with height (r= 0.523, P < 0.01 and r=-0.623, P < 0.001, respectively), but the b/a ratio was not significantly correlated with height. In study 2, the d/a ratio increased significantly (P≤ 0.05), but the b/a ratio and AGI did not alter. CONCLUSIONS: The SDPTG indices in children show characteristic alterations with advance of age and react to a vasodilator.

Rosiglitazone reduces plasma levels of inflammatory and hemostatic biomarkers and improves global endothelial function in habitual heavy smokers without diabetes mellitus or metabolic syndrome.

BACKGROUND/PURPOSE: Thiazolidinediones have anti-atherothrombotic effects in diabetic patients. However, the effects of rosiglitazone on inflammatory and hemostatic markers, as well as global endothelial function in non-diabetic smokers are unknown. METHODS: Twenty-seven healthy male heavy smokers without metabolic syndrome were enrolled in this double-blind, controlled study. Fourteen subjects received 4 mg/day rosiglitazone for 8 weeks (group R) and 13 subjects received placebo (group C). Changes in the reflection index (Delta RI) of beta-agonist-induced endothelium-dependent vasodilatation by photoplethysmography and plasma biomarkers were measured before and after treatment. RESULTS: Matrix metalloproteinase-9, fibrinogen, and high-sensitivity C-reactive protein were reduced significantly in group R after treatment as compared with the baseline [84.1 (45.6 139.0) vs. 123.9 (58.4 141.8) ng/mL, p = 0.03; 2914 (2400-3553) vs. 3220 (2542-3940) mg/L, p = 0.04; and 3.4 (2.2 5.1) vs. 5.5 (4.1 6.8) mg/L, p = 0.009, respectively]. Delta RI was improved markedly in group R as compared with the baseline [13.5 (4.2 65.1) vs. 2.5 (-10.6 to 9.3)%; p = 0.024]. These biomarkers and Delta RI did not differ significantly in the group C. There were no significant changes in fasting plasma glucose, insulin, homeostasis model assessment index, and lipid profile in both groups R and group C. CONCLUSION: Rosiglitazone significantly reduces plasma levels of inflammatory and hemostatic biomarkers, and restores global endothelial dysfunction, independently from insulin sensitization, in healthy smokers.

Comparing the effect of arginine vasopressin on ear and finger photoplethysmography.

STUDY OBJECTIVE: To test whether the relative insensitivity of craniofacial vessels to catecholamines differs in response to arginine vasopressin. DESIGN: Prospective, observational human study. SETTING: University hospital. PATIENTS: 8 ASA physical status I and II women scheduled for elective myomectomy. INTERVENTIONS: Patients underwent elective myomectomy surgery with intrauterine injection of arginine vasopressin. MEASUREMENTS: Finger, ear, and forehead photoplethysmographs were monitored. Changes in the plethysmographic amplitudes were recorded before and after arginine vasopressin injection. MAIN RESULTS: In all subjects, ear photoplethysmographic amplitude (but not oxygen saturation) decreased precipitously (62% +/- 10%; P < 0.001) after arginine vasopressin injection. In contrast, there was no significant decline in the finger signal (4.5% +/- 27%; P = 0.19). The forehead plethysmograph decreased in amplitude, but this finding did not achieve significance (33% +/- 18%; P = 0.18). CONCLUSION: In contrast to prior observations during adrenergic activation, arginine vasopressin induced relatively greater vasoconstriction at the ear and forehead than at the finger. This finding has potential implications with respect to arginine vasopressin's effect on blood flow and indicates that monitoring the ear plethysmographic signal may provide useful information during arginine vasopressin administration.

Assessment of vasoactive agents and vascular aging by the second derivative of photoplethysmogram waveform.

To evaluate the clinical application of the second derivative of the fingertip photoplethysmogram waveform, we performed drug administration studies (study 1) and epidemiological studies (study 2). In study 1, ascending aortic pressure was recorded simultaneously with the fingertip photoplethysmogram and its second derivative in 39 patients with a mean+/-SD age of 54+/-11 years. The augmentation index was defined as the ratio of the height of the late systolic peak to that of the early systolic peak in the pulse. The second derivative consists of an a, b, c, and d wave in systole and an e wave in diastole. Ascending aortic pressure increased after injection of 2.5 microg angiotensin from 126/74 to 160/91 mm Hg and decreased after 0.3 mg sublingual nitroglycerin to 111/73 mm Hg. The d/a, the ratio of the height of the d wave to that of the a wave, decreased after angiotensin from -0.40+/-0.13 to -0.62+/-0.19 and increased after nitroglycerin to -0.25+/-0.12 (P<0.001 and P<0.001, respectively). The negative d/a increased with increases in plethysmographic and ascending aortic augmentation indices (r=0.79, P<0.001, and r=0.80, P<0.001, respectively). The negative d/a reflects the late systolic pressure augmentation in the ascending aorta and may be useful for noninvasive evaluation of the effects of vasoactive agents. In study 2, the second derivative of the plethysmogram waveform was measured in a total of 600 subjects (50 men and 50 women in each decade from the 3rd to the 8th) in our health assessment center. The b/a ratio increased with age, and c/a, d/a, and e/a ratios decreased with age. Thus, the second derivative aging index was defined as b-c-d-e/a. The second derivative wave aging index (y) increased with age (x) (r=0.80, P<0.001, y=0.023x-1.515). The second derivative aging index was higher in 126 subjects with any history of diabetes mellitus, hypertension, hypercholesterolemia, and ischemic heart disease than in age-matched subjects without such a history (-0.06+/-0.36 versus -0.22+/-0.41, P<0.01). Women had a higher aging index than men (P<0.01). The b-c-d-e/a ratio may be useful for evaluation of vascular aging and for screening of arteriosclerotic disease.

Periodic cardiovascular and ventilatory activity during midazolam sedation.

We have examined the effects of sedation with midazolam 0.1 mg kg-1 and reversal with flumazenil 0.5 mg on beat-to-beat heart rate (HR) variability (HRV), systolic arterial pressure (SAP), finger photoplethysmograph amplitude (PLA) and impedence pneumography in eight volunteers. With the onset of sedation there was a small decrease in SAP and increase in HR (ns). Spectral analysis of the HR time series showed reductions in the proportion of power in the high (> 0.15 Hz) frequency "ventilatory" band consistent with midazolam causing vagolysis. During sedation, low frequency (< 0.05 Hz) oscillations of PLA, HR, SAP and ventilation were observed. These were thought to be secondary to activity of coupled cardiorespiratory neurones within the brain stem and the ventilatory periodicity appeared similar to that observed during the early stages of sleep. The diminished high frequency and increased low frequency oscillations induced by midazolam sedation were reversed by administration of flumazenil.