Noninvasive Arterial Blood Pressure Research Articles

Compromised dynamic cerebral autoregulation in patients with generalized anxiety disorder: a study using transfer function analysis

BackgroundPatients with generalized anxiety disorder (GAD) usually present with various neurological symptoms, but the mechanisms remain unclear. We aimed to analyze the characteristics of dynamic cerebral autoregulation (dCA) in patients with GAD.MethodsPatients (aged ≥18 years) who were diagnosed with GAD were enrolled in this study. Medically and psychiatrically healthy volunteers were recruited as controls. Subjects received the Hamilton Rating Scale for Anxiety (HAMA) and 17-item Hamilton Depression Rating Scale (HAMD) evaluation. Noninvasive continuous arterial blood pressure and bilateral middle cerebral artery blood flow velocity were recorded simultaneously from each subject. Transfer function analysis was used to derive the autoregulatory parameters, including phase difference, gain, and coherence function.ResultsA total of 57 patients with GAD and 40 healthy volunteers were enrolled. We found that the phase difference values were significantly compromised in patients with GAD. In the Spearman correlation analysis, the phase difference values were negatively correlated with the HAMA scores and the HAMD scores. In the multiple linear regression analysis, GAD is negatively correlated with the phase difference values, whereas age is positively correlated with the phase difference values.ConclusionsOur results suggested that the dCA was compromised in patients with GAD and negatively correlated with the score of anxiety. Improving the dCA may be a potential therapeutic method for treating the neurological symptoms of GAD patients.

Assessment of cerebral hemodynamic parameters using pulsatile versus non-pulsatile cerebral blood outflow models.

Prior methods evaluating the changes in cerebral arterial blood volume (∆CaBV) assumed that brain blood transport distal to big cerebral arteries can be approximated with a non-pulsatile flow (CFF) model. In this study, a modified ∆CaBV calculation that accounts for pulsatile blood flow forward (PFF) from large cerebral arteries to resistive arterioles was investigated. The aim was to assess cerebral hemodynamic indices estimated by both CFF and PFF models while changing arterial blood carbon dioxide concentration (EtCO2) in healthy volunteers. Continuous recordings of non-invasive arterial blood pressure (ABP), transcranial Doppler blood flow velocity (CBFVa), and EtCO2 were performed in 53 young volunteers at baseline and during both hypo- and hypercapnia. The time constant of the cerebral arterial bed (τ) and critical closing pressure (CrCP) were estimated using mathematical transformations of the pulse waveforms of ABP and CBFVa, and with both pulsatile and non-pulsatile models of ∆CaBV estimation. Results are presented as median values ± interquartile range. Both CrCP and τ gave significantly lower values with the PFF model when compared with the CFF model (p ≪ 0.001 for both). In comparison to normocapnia, both CrCP and τ determined with the PFF model increased during hypocapnia [CrCPPFF (mmHg): 5.52 ± 8.78 vs. 14.36 ± 14.47, p = 0.00006; τPFF (ms): 47.4 ± 53.9 vs. 72.8 ± 45.7, p = 0.002] and decreased during hypercapnia [CrCPPFF (mmHg): 5.52 ± 8.78 vs. 2.36 ± 7.05, p = 0.0001; τPFF (ms): 47.4 ± 53.9 vs. 29.0 ± 31.3, p = 0.0003]. When the CFF model was applied, no changes were found for CrCP during hypercapnia or in τ during hypocapnia. Our results suggest that the pulsatile flow forward model better reflects changes in CrCP and in τ induced by controlled alterations in EtCO2.

Continuous noninvasive arterial blood pressure monitoring using the vascular unloading technology during complex gastrointestinal endoscopy: a prospective observational study.

The innovative vascular unloading technology (VUT) allows continuous noninvasive arterial blood pressure (AP) monitoring. We aimed to investigate whether the VUT enables AP changes to be detected earlier compared with intermittent AP monitoring in patients undergoing gastrointestinal endoscopy. In this prospective observational study, we recorded continuous AP measurements with the VUT (CNAP system; CNSystems Medizintechnik AG, Graz, Austria) and intermittent AP measurements with upper arm cuff oscillometry in 90 patients undergoing complex gastrointestinal endoscopy (Department of Interventional Endoscopy at the University Medical Center Hamburg-Eppendorf, Hamburg, Germany). A "hypotensive phase" was defined as a time period of at least 30s during which ≥ 50% of the VUT-AP values were in a predefined range of hypotension, i.e., AP value a) ≥ 10% below the last oscillometric value and b) ≤ 65mmHg for mean AP or ≤ 90mmHg for systolic AP. In the 5-min-interval between two oscillometric measurements, one or more hypotensive phases were detected in 26 patients (29%) for mean AP and in 27 patients (30%) for systolic AP. Hypotensive phases had a mean duration of 195 ± 99s for mean AP and 197 ± 97s for systolic AP with a mean procedure duration of 36 (± 21) min. Continuous noninvasive AP monitoring using the VUT enables hypotensive phases to be detected earlier compared with intermittent AP monitoring during complex gastrointestinal endoscopy. These hypotensive phases may be missed or only belatedly recognized with intermittent AP monitoring. Continuous noninvasive AP measurement facilitates detecting hemodynamic instability more rapidly and therefore may improve patient safety.

Prospective clinical study to evaluate an oscillometric blood pressure monitor in pet rabbits

BackgroundRabbits are particularly sensitive to develop hypotension during sedation or anaesthesia. Values of systolic or mean non-invasive arterial blood pressure below 80 or 60 mmHg respectively are common under anaesthesia despite an ongoing surgery. A reliable method of monitoring arterial blood pressure is extremely important, although invasive technique is not always possible due to the anatomy and dimension of the artery. The aim of this study was to evaluate the agreement between a new oscillometric device for non-invasive arterial blood pressure measurement and the invasive method. Moreover the trending ability of the device, ability to identify changes in the same direction with the invasive methods, was evaluated as well as the sensibility of the device in identifying hypotension arbitrarily defined as invasive arterial blood pressure below 80 or 60 mmHg.ResultsBland-Altman analysis for repeated measurements showed a poor agreement between the two methods; the oscillometric device overestimated the invasive arterial blood pressure, particularly at high arterial pressure values. The same analysis repeated considering oscillometric measurement that match invasive mean pressure lower or equal to 60 mmHg showed a decrease in biases and limits of agreement between methods. The trending ability of the device, evaluated with both the 4-quadrant plot and the polar plot was poor. Concordance rate of mean arterial blood pressure was higher than systolic and diastolic pressure although inferior to 90%. The sensibility of the device in detecting hypotension defined as systolic or mean invasive arterial blood pressure lower than 80 or 60 mmHg was superior for mean oscillometric pressure rather than systolic. A sensitivity of 92% was achieved with an oscillometric measurement for mean pressure below 65 mmHg instead of 60 mmHg. Non-invasive systolic blood pressure is less sensitive as indicator of hypotension regardless of the cutoff limit considered.ConclusionsAlthough mean invasive arterial blood pressure is overestimated by the device, the sensitivity of this non-invasive oscillometric monitor in detecting invasive mean pressure below 60 mmHg is acceptable but a cutoff value of 65 mmHg needs to be used.

The effect of positive end-expiratory pressure during anesthesia on arterial oxygen saturation after surgery in patient undergoing cesarean section.

One of the major complications of general anesthesia in the recovery room is arterial oxygen desaturation and hypoxemia. Positive end-expiratory pressure (PEEP) can improve arterial oxygen saturation by increasing FRC. This study aims to evaluate the effects of applying PEEP on arterial oxygen saturation and hemodynamic parameters in the patient undergoing cesarean section in VALIASR hospital. In this double blind clinical trial we randomly allocated 120 patients of class1 and 2 ASA scheduled to undergoing cesarean section into 3 group (in 40).Different levels of PEEP (0, 5 and 10 CmH2o) were applied to each group while zero PEEP was established as control. All other variables (anesthesia and surgery techniques) were the same for all patients SPO2, noninvasive mean arterial pressure and heart rate were measured before, during and after surgery (Recovery room). The comparison of noninvasive arterial blood pressure and heart rate during and after surgery did not show significant differences but mean o2 saturation in group B (5 cmH2o PEEP) and C (10 cm H2o PEEP) in PACU was higher than control group (98.30±0.93 and 98.50±0.90 as opposed to97.12±1.15 respectively) P<0.001. In light of results applying PEEP is effective in preventing desaturation after surgery and improving respiratory indexes without the significant hemodynamic changes, the result of using five cmH2o PEEP is more efficient and satisfying.

Noninvasive continuous blood pressure monitoring by the ClearSight system during robot-assisted laparoscopic radical prostatectomy.

Robot-assisted laparoscopic radical prostatectomy (RALRP) is commonly performed in the surgical treatment of prostate cancer. However, the steep Trendelenburg position (25) and pneumoperitoneum required for this procedure can sometimes cause hemodynamic changes. Although blood pressure is traditionally monitored invasively during RALRP, the ClearSight system (BMEYE, Amsterdam, The Netherlands) enables a totally noninvasive and simple continuous blood pressure and cardiac output monitoring based on finger arterial pressure pulse contour analysis. We therefore investigated whether noninvasive continuous arterial blood pressure measurements using the ClearSight system were comparable to those obtained invasively in patients undergoing RALRP. Ten patients scheduled for RALRP with American Society of Anesthesiologists physical status I-II were included in this study. At each of the seven defined time points, noninvasive and invasive blood pressure measurements were documented and compared in each patient using Bland-Altman analysis. Although the blood pressure measured with the ClearSight system correlated with that measured invasively, a large difference between the values obtained by the two devices was noted. The ClearSight system was unable to detect blood pressure accurately during RALRP, suggesting that blood pressure monitoring using this device alone is not feasible in this small patient population. J. Med. Invest. 65:69-73, February, 2018.

A Waveform Archiving System for the GE Solar 8000i Bedside Monitor.

Our objective was to develop, deploy, and test a data-acquisition system for the reliable and robust archiving of high-resolution physiological waveform data from a variety of bedside monitoring devices, including the GE Solar 8000i patient monitor, and for the logging of ancillary clinical and demographic information. The data-acquisition system consists of a computer-based archiving unit and a GE Tram Rac 4A that connects to the GE Solar 8000i monitor. Standard physiological front-end sensors connect directly to the Tram Rac, which serves as a port replicator for the GE monitor and provides access to these waveform signals through an analog data interface. Together with the GE monitoring data streams, we simultaneously collect the cerebral blood flow velocity envelope from a transcranial Doppler ultrasound system and a non-invasive arterial blood pressure waveform along a common time axis. All waveform signals are digitized and archived through a LabView-controlled interface that also allows for the logging of relevant meta-data such as clinical and patient demographic information. The acquisition system was certified for hospital use by the clinical engineering team at Boston Medical Center, Boston, MA, USA. Over a 12-month period, we collected 57 datasets from 11 neuro-ICU patients. The system provided reliable and failure-free waveform archiving. We measured an average temporal drift between waveforms from different monitoring devices of 1 ms every 66 min of recorded data. The waveform acquisition system allows for robust real-time data acquisition, processing, and archiving of waveforms. The temporal drift between waveforms archived from different devices is entirely negligible, even for long-term recording.

The impact of continuous non-invasive arterial blood pressure monitoring on blood pressure stability during general anaesthesia in orthopaedic patients: A randomised trial.

In patients undergoing general anaesthesia, intraoperative hypotension occurs frequently and is associated with adverse outcomes such as postoperative acute kidney failure, myocardial infarction or stroke. A history of chronic hypertension renders patients more susceptible to a decrease in blood pressure (BP) after induction of general anaesthesia. As a patient's BP is generally monitored intermittently via an upper arm cuff, there may be a delay in the detection of hypotension by the anaesthetist. The current study investigates whether the presence of continuous BP monitoring leads to improved BP stability. Randomised, controlled and single-centre study. A total of 160 orthopaedic patients undergoing general anaesthesia with a history of chronic hypertension. The patients were randomised to either a study group (n = 77) that received continuous non-invasive BP monitoring in addition to oscillometric intermittent monitoring, or a control group (n = 83) whose BP was monitored intermittently only. The interval for oscillometric measurements in both groups was set to 3 min. After induction of general anaesthesia, oscillometric BP values of the two groups were compared for the first hour of the procedure. Anaesthetists were blinded to the purpose of the study. BP stability and hypotensive events. There was no difference in baseline BP between the groups. After adjustment for multiple testing, mean arterial BP in the study group was significantly higher than in the control group at 12 and 15 min. Mean ± SD for study and control group, respectively were: 12 min, 102 ± 24 vs. 90 ± 26 mmHg (P = 0.039) and 15 min, 102 ± 21 vs. 90 ± 23 mmHg (P = 0.023). Hypotensive readings below a mean pressure of 55 mmHg occurred more often in the control group (25 vs. 7, P = 0.047). Continuous monitoring contributes to BP stability in the studied population. NCT02519101.

Bispectral-Index-measured sevoflurane requirement might be decreased in individuals with major depressive disorder.

GABA (γ-aminobutyric acid) is the primary inhibitory neurotransmitter in the CNS and well-known target for general anesthetics. In addition, the dysregulation of GABA could be involved in the etiology of major depressive disorder (MDD). In this study, we aimed to determine whether MDD has any effect on anesthetic requirement measured by Bispectral Index (BIS). This study was designed as a prospective, observational study, registered ANZCTR (ACTRN 12616001295437), with institutional review board approval and written informed consent. Inpatients who were planned to undergo laparoscopic cholecystectomy as an elective surgery, were enrolled in this study. Patients were divided into two groups, based on the results of the Beck Depression Inventory (BDI) which was assessed the 21-item self-administered scale measuring various symptoms of depression. If the BDI score was under 10, it was accepted as control group. Patients were consulted to the psychiatrist if the BDI score was 17 or more. Patients who were diagnosed as MDD by the psychiatrist, were classified as MDD group. Anesthesia was standardized, and delivered sevoflurane concentration was adjusted according to BIS value in both groups. Parameters of the study were heart rate, non-invasive arterial blood pressure, arterial oxygen saturation, BIS, end-tidal carbon dioxide, and end-tidal concentration of sevoflurane at 5-minute intervals during the operation. End-tidal concentration of sevoflurane was found to be lower in MDD group during the maintenance phase of anesthesia. Mean end-tidal concentration of sevoflurane were significantly lower in MDD group (1.28±0.15) than control group (1.52±0.22) (P<0.0001). BIS values were lower at 5- and 10-minute intervals in MDD group in comparison with control group. BIS values were similar at other time intervals in both groups during surgery. MDD might result in decreased end-tidal concentration of sevoflurane. Further study is required to identify the relationship between MDD and anesthetics.

Sedative and cardiovascular effects of intranasal or intramuscular dexmedetomidine in healthy dogs

ObjectiveTo compare the clinical effects and sedation scores following either intranasal (IN) or intramuscular (IM) administration of dexmedetomidine in dogs. Study designProspective, blinded, randomized, clinical study. AnimalsA total of 20 client-owned dogs scheduled for noninvasive diagnostic procedures. MethodsDogs were allocated to be administered dexmedetomidine 0.02 mg kg−1 IN (IN group) or IM (IM group). Sedation was scored before and at 5 minute intervals (for 45 minutes) after drug administration using a composite simple descriptive sedation scale giving a score of 0 (not sedated) to 13 (well sedated). Respiratory frequency (fR), heart rate, haemoglobin oxygen saturation (SpO2) and noninvasive arterial blood pressure were recorded every 5 minutes for 45 minutes. Normally distributed data were analyzed using two-way ANOVA and post hoc Sidak's multiple comparison test. Non-normally distributed data were compared using the Scheier Ray Hare test and post hoc Mann–Whitney U test. Statistical significance was set at p<0.05. ResultsWeight, age and sex were not different between groups. Dexmedetomidine onset of action after IN administration was not shorter compared to IM administration (6.3±3.3 versus 9.4±4.6 minutes, p=0.120). Sedation score in the IN group was higher [10 (0–11)] compared to the IM group [6 (0–8)] (p<0.001). At time of peak sedation, heart rate decreased 56% from baseline values in the IM group, and 18% in the IN group. No significant differences in SpO2 and fR were found between the two groups at any time point. No undesirable effects were observed. Conclusions and clinical relevanceIntranasal dexmedetomidine 0.02 mg kg−1 produced effective sedation with less bradycardia and more profound sedation compared to IM administration in healthy dogs and may be considered as an alternative route for dexmedetomidine administration in dogs.

Comparison of medetomidine—morphine and medetomidine—methadone for sedation, isoflurane requirement and postoperative analgesia in dogs undergoing laparoscopy

ObjectiveTo compare the effects of intravenous (IV) medetomidine-morphine and medetomidine-methadone on preoperative sedation, isoflurane requirements and postoperative analgesia in dogs undergoing laparoscopic surgery. Study designRandomized, crossover trial. AnimalsTwelve adult Beagle dogs weighing 15.1 ± 4.1 kg. MethodsDogs were administered medetomidine (2.5 μg kg−1) IV 5 minutes before either methadone (MET) or morphine (MOR) (0.3 mg kg−1) IV. Anaesthesia was induced with propofol, maintained with isoflurane in oxygen, and depth was clinically assessed and adjusted by an anaesthetist blinded to the treatment. Animals underwent laparoscopic abdominal biopsies. Sedation and nausea scores, pulse rate (PR), respiratory rate (fR), noninvasive systolic arterial blood pressure (SAP), rectal temperature (RT) and pain scores were recorded before drug administration, 5 minutes after medetomidine injection and 10 minutes after opioid administration. Propofol dose, PR, fR, SAP, oesophageal temperature (TOES), end-tidal carbon dioxide and end-tidal isoflurane concentration (Fe′Iso) were recorded intraoperatively. Pain scores, PR, fR, SAP and RT were recorded 10 minutes after extubation, every hour for 6 hours, then at 8, 18 and 24 hours. The experiment was repeated with the other drug 1 month later. ResultsNine dogs completed the study. After opioid administration and intraoperatively, PR, but not SAP, was significantly lower in MET. Fe′Iso was significantly lower in MET. Temperature decreased in both treatments. Pain scores were significantly higher in MOR at 3 hours after extubation, but not at other time points. Two dogs required rescue analgesia; one with both treatments and one in MOR. Conclusion and clinical relevanceAt the dose used, sedation produced by both drugs when combined with medetomidine was equivalent, while volatile anaesthetic requirements and PR perioperatively were lower with methadone. Postoperative analgesia was deemed to be adequate for laparoscopy with either protocol, although methadone provided better analgesia 3 hours after surgery.

Effectiveness of Balloon Angioplasty in Children With Recurrent Aortic Coarctation Depends on the Type of Aortic Arch Pathology.

The aim of this study was to evaluate the effectiveness of balloon angioplasty (BAP) for recurrent aortic coarctation (ReCoA) in infants comparing simple and complex type of aortic arch pathology (Norwood I procedure). ReCoA is a known complication after cardiovascular surgery for coarctation of the aortic arch. In a single center case study, we analyzed 20 infants undergoing BAP for ReCoA comparing simple (n = 10) and complex type of aortic arch pathology (n = 10). At catherization diameter of ReCoA stenosis was 3.2 ± 0.7 mm (mean ± SD) with short localized (11/20) or long hypoplastic stenosis (9/20) before and 4.8 ± 1.2 mm after BAP (P < 0.001). Invasive systolic pressure gradient was reduced from 27.5 ± 16.2 mmHg before to 5.1 ± 6.6 mmHg after BAP (P < 0.001), comparable in simple and complex type of ReCoA. At day 1 after catherization noninvasive systolic arterial blood pressure gradient was reduced from 20.2 ± 23.1 to 6.7 ± 9.9 mmHg (P < 0.001), respectively, calculated continuous wave Doppler echo gradient from 36.3 ± 22 to 16.8 ± 9.6 mmHg (P < 0.01). Complications were aortic arch dissection (1/20), discrete aortic arch aneurysm formation (1/20), pericardial effusion (1/20), and peripheral arterial thrombosis (4/20). At a mid-term follow up of 9.5 months (1-40) after BAP, 3 infants needed early surgical reintervention due to secondary ReCoA, all with long hypoplastic aortic arch segments, but simple type of aortic arch pathology. At mid-term follow up, BAP remains an effective catheter intervention for ReCoA for infants with localized ReCoA, but not with long hypoplastic aortic arch segments, even in simple type of aortic arch pathology.

Insomnia may increase anesthetic requirement

Study ObjectiveGamma aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system. It is a common target for general anesthetics, and it is strongly related to the etiology of chronic insomnia. In this study, we aimed to investigate whether insomnia has any effect on anesthetic requirement, and we also assessed pain to reveal a relationship with insomnia. DesignThis study designed as a prospective, observational study, registered ANZCTR (ACTRN12616000241437), with institutional review board approval and written informed consent. SettingPreoperative and postoperative areas of the training and research hospital. PatientsInpatients planning to undergo laparoscopic cholecystectomy as an elective surgery were enrolled in this study. InterventionsPatients were divided into 2 groups based on the results of the 4-item Jenkins Sleep Questionnaire which assesses the degree of sleep disturbance: those with or without insomnia. Anesthesia was standardized, and delivered sevoflurane concentration was adjusted according to bispectral index (BIS) value in both groups. MeasurementsParameters of the study were heart rate, noninvasive arterial blood pressure, arterial oxygen saturation, BIS, end-tidal carbon dioxide, and inspiratory and end-tidal concentrations of sevoflurane at 5-minute intervals during the operation. Pain was assessed for all participants; preoperatively using 2-sided blank body manikin (front and back) and postoperatively with numeric rating scale between 0 and 10. Main ResultsEnd-tidal concentration of sevoflurane found higher in insomnia group during the maintenance phase of anesthesia. Pain experience was higher in insomnia group. In addition, postoperative abdominal pain score was higher only at 18-hour interval in insomnia group. Although BIS values were similar in both groups during surgery, mean end-tidal sevoflurane concentrations were significantly higher in insomnia group (1.48±0.20) than control group (1.23±0.18) (P<.0001). ConclusionInsomnia may result in increased anesthetic requirement and pain experience. Further study is required to identify the relationship between insomnia and anesthetics.

The effects of intravenous lidocaine before propofol induction in premedicated dogs.

The effects of lidocaine, administered before induction of anaesthesia with propofol, on arterial blood pressure, heart rate, respiratory rate, cough reflex, ease of intubation, extrapyramidal signs and required dose of propofol in healthy premedicated dogs were evaluated. Twenty-four client-owned dogs were premedicated intramuscularly with 1 µg/kg dexmedetomidine and 0·2 mg/kg methadone, and randomly allocated to receive 2 mg/kg lidocaine (group L) or saline (group P) 120 seconds before induction of anaesthesia with propofol. Heart rate, non-invasive arterial blood pressure and respiratory rate were assessed at pre-established intervals. Quality of intubation, cough reflex and the occurrence of adverse effects were scored according to predefined scales. The total amount of propofol administered was also recorded. Cardiovascular and respiratory variables changed over time but were not significantly different between treatments. No significant differences between groups were found for the incidence of coughing, quality of intubation, adverse effects and propofol intubation dose. Intravenous administration of lidocaine 2 mg/kg before propofol induction was not associated with significant cardiovascular and respiratory benefits compared to standard induction and did not result in a propofol dose-sparing effect or improvement of the quality of intubation in dogs premedicated with dexmedetomidine and methadone.

Assessing the eligibility of a non-invasive continuous blood pressure measurement technique for application during total intravenous anaesthesia.

To assess the eligibility for replacement of invasive blood pressure as measured "within" the arterial vessel (IBP) with non-invasive continuous arterial blood pressure (cNIP) monitoring during total intravenous anaesthesia (TIVA), the ability of cNiP to track fast blood pressure changes needs to be quantified. A new method of statistical data analysis is developed for this purpose. In a pilot study on patients undergoing neurosurgical anaesthesia, mean arterial pressure MAPIBP measured with IBP was compared to MAPCNP measured by the CNAP Monitor 500 in ten patients (age: 63±13 a). Correlation analysis of changes of device differences ΔeMAP=ΔMAPCNP-ΔMAPIBP with changes of MAPIBP (ΔMAPIBP) during intervals of vasoactivity was conducted. An innovative technique, of linear trend analysis (LTA) applied to two signals, is described to perform this analysis without a priori knowledge of intervals of vasoactivity. Analysis of ΔeMAP during vasoactivity revealed that ΔMAPCNP systematically underestimated ΔMAPIBP by 37%. This was confirmed in the complete data set using LTA technique showing a systematic, yet patient specific, underestimation in tracking ΔMAPIBP (16…120%). The proposed LTA technique is able to detect systematic errors in tracking short-term blood pressure changes otherwise masked by established analysis. LTA may thus be a useful tool to assess the eligibility of cNIP to replace IBP during TIVA.

Comparison of the effects of propofol and emulsified isoflurane alone or combined with dexmedetomidine on induction of anesthesia in dogs

ObjectiveTo compare the respective effects of propofol and emulsified isoflurane administered alone and in combination with dexmedetomidine on the quality of induction of anesthesia, physiological variables and recovery in dogs. Study designProspective, randomized, experimental trial. AnimalsThirty-six adult mixed-breed dogs. MethodsAnimals were randomly assigned to one of four induction protocols: propofol alone (group P); emulsified isoflurane alone (group EI); both propofol and dexmedetomidine (group PD), or both emulsified isoflurane and dexmedetomidine (group EID). Pulse rate (PR), respiratory rate (fR), non-invasive arterial blood pressure and arterial blood gases were measured at baseline, before induction, immediately after intubation (time 0), and at 5 minute intervals until the dog began to swallow and the trachea was extubated. The quality of induction and recovery, and degree of ataxia were scored by a single investigator unaware of group assignment. The durations of anesthesia and recovery, and the incidence of adverse events were recorded. ResultsThere were no clinically significant differences among the groups in induction quality. Systolic arterial pressure was lower in EID compared with P at 5 minutes. PR and fR were lower in PD and EID compared with P after induction. The PaCO2 at 5 minutes was higher than at baseline in group P. Ataxia score was lower in EID than in P. Time from induction to extubation and time from extubation to sternal recumbency were lower in EID compared with PD. Conclusions and clinical relevanceThere were no clinically significant differences among the groups in induction quality. In PD and EID, but not in P, PR and fR were decreased after induction. The EID combination resulted in smooth and rapid induction and recovery and thus may be useful clinically for induction of anesthesia.

Temporal Course of Dynamic Cerebral Autoregulation in Patients With Intracerebral Hemorrhage.

Cerebral autoregulation is crucial in patients with intracerebral hemorrhage. Dynamic cerebral autoregulation is probably altered in acute intracerebral hemorrhage; however, the temporal course of dynamic cerebral autoregulation and its correlation with clinical factors and outcomes are poorly understood. Forty-three acute supratentorial intracerebral hemorrhage patients (53.7±10.0 years old, 30 men) were enrolled for serial measurements performed on days 1 to 2, 4 to 6, 10 to 12, and 30 days after ictus. Noninvasive continuous cerebral blood flow velocity and arterial blood pressure were recorded simultaneously using transcranial Doppler and a servo-controlled plethysmograph, respectively. Transfer function analysis was used to derive the autoregulatory parameters, including phase difference (PD), gain, and the rate of recovery of cerebral blood flow velocity. Results were compared with healthy controls and correlated with clinical factors and the 90-day outcome. PD did not differ between affected and unaffected hemispheres over time. A significant lower PD (indicating dynamic cerebral autoregulation impaired) was found in bilateral hemispheres on days 1 to 2, 4 to 6, and 10 to 12, followed by later recovery on day 30. Lower bilateral PD on days 1 to 2 was associated with poorer Glasgow Coma Scale score at that time. Lower affected-side PD on days 4 to 6 was an independent predictive value for a poorer modified Rankin Scale at 90 days. In patients with supratentorial intracerebral hemorrhage, dynamic cerebral autoregulation is bilaterally impaired lasting at least 10 to 12 days and recovers within a month. Individual PD value is associated with clinical status at acute stage and affected-side PD on days 4 to 6 can be an independent predictor for clinical outcome.

Exercise performance in young patients with complete atrioventricular block: the relevance of synchronous atrioventricular pacing.

At present, there are many pacing strategies for young patients with complete atrioventricular block. The most frequent policy is to attempt placing a dual-chamber system when possible; however, there is a group of patients that is functioning with a non-synchronous ventricular pacing, raising the question of the ideal timing to upgrade their systems. We investigated the exercise performance of a group of children and young adults with complete atrioventricular block and dual-chamber pacemakers in both single- and dual-chamber pacing modalities. A total of 15 patients performed maximal exercise stress testing after programming the VVIR or DDD modes with 2 hours of interval in a double-blind study protocol. Compared with VVIR pacing, DDD pacing resulted in increase in the peak VO2, longer test duration, major increase in the heart rate achieved during peak exercise, decreased systemic non-invasive arterial blood pressure measured at maximal exercise, higher maximal workload, prolongation of the anaerobic threshold timing, and better self-rated performance perception in all the patients. Synchronous atrioventricular pacing contributes to an increase in both the exercise performance and the performance perception in 100% of the patients. This difference contributes to create a sense of "fitness" with repercussions in the overall health, self-esteem, and life quality, as well as encourages youngster to practice sports. Our experience tends to favour upgrading patients' systems to dual-chamber systems before reaching the adolescent years, even if the centre policy is to prolong as long as possible the epicardial site in order to avoid long years of right ventricular pacing.

Dynamic Cerebral Autoregulation in Asymptomatic Patients With Unilateral Middle Cerebral Artery Stenosis.

The aim of the study was to assess the capacity of dynamic cerebral autoregulation (dCA) in asymptomatic patients with unilateral middle cerebral artery (MCA) stenosis.Fifty-seven patients with asymptomatic mild, moderate, and severe unilateral MCA stenosis and 8 patients with symptomatic severe unilateral MCA stenosis diagnosed by transcranial Doppler were enrolled. Twenty-four healthy volunteers served as controls. The noninvasive continuous cerebral blood flow velocity and arterial blood pressure were recorded simultaneously from each subject in the supine position. Transfer function analysis was applied to determine the autoregulatory parameters (phase difference [PD] and gain).The PD values in the severe stenosis groups were significantly lower than those of the control group (60.71 ± 18.63°), the asymptomatic severe stenosis group was impaired ipsilaterally (28.94 ± 27.43°, P < 0.001), and the symptomatic severe stenosis group was impaired bilaterally (13.74 ± 19.21°, P < 0.001; 19.68 ± 14.50°, P = 0.006, respectively). The PD values in the mild and moderate stenosis groups were not significantly different than the controls (44.49 ± 27.93°; 48.65 ± 25.49°, respectively). The gain values in the mild and moderate groups were higher than in the controls (1.00 ± 0.58 cm/s/mm Hg vs 0.86 ± 0.34 cm/s/mm Hg, and 1.20 ± 0.59 cm/s/mm Hg vs 0.86 ± 0.34 cm/s/mm Hg, respectively). The gain values in the severe stenosis groups were significantly lower than that in the control group: the asymptomatic severe stenosis group was lower bilaterally (0.56 ± 0.32 cm/s/mm Hg, P = 0.003; 0.60 ± 0.32 cm/s/mm Hg, P < 0.05, respectively), whereas the symptomatic severe group was lower unilaterally (on the contralateral side) (0.53 ± 0.43 cm/s/mm Hg, P < 0.05).In asymptomatic patients with unilateral MCA stenosis, only the dCA of the severe stenosis was ipsilaterally impaired. Acute stroke may aggravate the impaired dCA and even spread contralaterally.

Detection of volume loss using the Nexfin device in blood donors.

We investigated which haemodynamic parameters derived from Nexfin non-invasive continuous arterial blood pressure measurements are optimal to detect controlled volume loss in spontaneously breathing subjects. Haemodynamic monitoring was performed in 40 whole-blood donors. Mean arterial pressure, cardiac index, systemic vascular resistance index and pulse pressure variation were recorded during controlled breathing, and a Valsalva manoeuvre was performed before and after blood donation. Blood donation resulted in a reduction in cardiac index (from 3.96 ± 0.84 l.min(-1) .m(2) to 3.30 ± 0.61 l.min(-1) .m(2) ; p < 0.001), an increase in systemic vascular resistance (from 1811 ± 450 dyn.s.cm(-5) .m(2) to 2137 ± 428 dyn.s.cm(-5) .m(2) ; p < 0.001) and an increase in pulse pressure variation (from 13.4 ± 5.1 to 15.3 ± 5.4%; p = 0.02). The area under the receiver operating characteristic curve to detect volume loss was highest for cardiac index (0.94, 95% CI 0.88-0.99) and systemic vascular resistance (0.90, 95% CI 0.82-0.99). Nexfin is a non-invasive haemodynamic monitor that can feasibly detect volaemic changes in spontaneously breathing subjects.