Time-varying spectral analysis revealing differential effects of sevoflurane anaesthesia: non-rhythmic-to-rhythmic ratio.

BACKGROUND: Heart rate variability (HRV) may reflect various physiological dynamics. In particular, variation of R-R peak interval (RRI) of electrocardiography appears regularly oscillatory in deeper levels of anaesthesia and less regular in lighter levels of anaesthesia. We proposed a new index, non-rhythmic-to-rhythmic ratio (NRR), to quantify this feature and investigated its potential to estimate depth of anaesthesia. METHODS: Thirty-one female patients were enrolled in this prospective study. The oscillatory pattern transition of RRI was visualised by the time-varying power spectrum and quantified by NRR. The prediction of anaesthetic events, including skin incision, first reaction of motor movement during emergence period, loss of consciousness (LOC) and return of consciousness (ROC) by NRR were evaluated by serial prediction probability (PK ) analysis; the ability to predict the decrease of effect-site sevoflurane concentration was also evaluated. The results were compared with Bispectral Index (BIS). RESULTS: NRR well-predicted first reaction (PK > 0.90) 30 s ahead, earlier than BIS and significantly better than HRV indices. NRR well-correlated with sevoflurane concentration, although its correlation was inferior to BIS, while HRV indices had no such correlation. BIS indicated LOC and ROC best. CONCLUSIONS: Our findings suggest that NRR provides complementary information to BIS regarding the differential effects of anaesthetics on the brain, especially the subcortical motor activity.

Participation of nucleus reticularis gigantocellularis in the antinociceptive effect of angiotensin III in the rat.

We evaluated the participation of nucleus reticularis gigantocellularis (NRGC), a medullary nucleus that plays an important role in the regulation of nociceptive processes, in the antinociceptive effect of angiotensin III (AIII), a biologically active peptide of the renin-angiotensin system. Adult, male Sprague-Dawley rats anesthetized with pentobarbital sodium (40 mg/kg, i.p., with 10 mg/kg/h i.v. infusion supplement) were used. Bilateral, site-specific microinjection of AIII (80 or 160 pmol) into the NRGC produced a dose-related increase in the latency of tail-flick response to noxious thermal stimuli (50 degrees C hot water). Such an antinociceptive action of AIII was blocked by concomitant administration of the AIII receptor antagonist, Ile7-angiotensin III (Ile7-AIII, 10 nmol). At the neuronal level, microiontophoretic application of AIII suppressed, Ile7-AIII reversibly, the responsiveness of nociception-related neurons in the NRGC to tail-clamping. These results demonstrated that central AIII may elicit antinociception via a process that may at least take place at the NRGC.

Heart rate variability in neonatal rats after perinatal cocaine exposure.

Pregnant rats received saline once daily (Control QD) or twice daily (Control BID), cocaine 2 mg/kg IV daily (COC QD) or twice daily (COC BID) throughout gestation beginning on gestational day 4. The treatment was continued in nursing mothers until postnatal day 7. All studies were performed in their offsprings on postnatal days 1 and 7. An age-dependent increase in heart rate was observed from D1 to D7 in all four groups of animals. Cocaine exposure significantly increased heart rate in the once daily treatment group on D1 and D7. In contrast, twice daily cocaine exposure did not alter heart rate. Maturational changes in heart rate variability (HRV) were also documented. Low-frequency (LF: 0.25-0.8 Hz) power of HRV is a marker of both sympathetic and parasympathetic influences. and high-frequency (HF: 0.8-2.4 Hz) power is a marker of efferent vagal activity. Total power (TP) is the sum of LF and HF. TP, normalized units of LF (LF as percent of TP), and normalized HF power decreased from D1 to D7 in all groups. Cocaine treatment affected both LF and HF powers and there was an interaction between cocaine treatment and age for both LF and HF. Although LF/HF ratio decreased from D1 to D7 in both groups of control animals. LF/HF did not change from D1 to D7 in either cocaine-treated group. Thus, cocaine exposure significantly attenuated the age-dependent change in LF/HF. Our results indicated that there were normal developmental changes in HRV consistent with continued postnatal development of autonomic nervous system. Perinatal cocaine exposure appeared to modify these changes. The specific autonomic mechanism for the cocaine effect may be a decline in parasympathetic activity and a concomitant change in sympathetic activity.

Pseudomonas cepacia induced septic shock after propofol--a case report.

We report a healthy young female who developed septic shock and multiple organ failure soon after receiving a cosmetic surgery for augmentation of breasts under general anesthesia. Blood cultures yielded the growth of pseudomonas cepacia. We describe the clinical course and investigate the causes of the septic shock. Contamination of propofol, the intravenous anesthetic agent, was suspected.

Anesthetic managements of the patients with giant mediastinal tumors--a report of two cases.

Anesthesia for patients with a huge anterior mediastinal tumor is a well-known challenge and trial to all the anesthesiologists. The tumor mass which directly compresses the trachea and bronchus induces hypoxia and asphyxia, eventuating in cardiac arrest or even fatality in the process of general anesthesia. In selection of anesthetic technique, general anesthesia is deliberately avoided if not mandatory or spontaneous respiration should be strictly preserved by all means if obligatory. Our surgical colleagues are usually not so familiar with this potentially life-threatening situation as are the anesthesiologists, and bad communications and interactions between the two may court disaster. Here we reported 2 cases: the former was an immediate mortality in a youth with a giant anterior mediastinal tumor undergoing excisional biopsy of a neck mass under general anesthesia, and the latter was a successful anesthetic management in a woman with a giant mediastinal tumor receiving abdominal total hysterectomy for cervical cancer in situ under spinal anesthesia. The hazards of general anesthesia in these patients and the importance of comprehending preanesthetic preparations were reviewed and discussed. Moreover, we address that whenever one has shot his bolt still futile to improve the respiratory crisis in a case with mediastinal tumor, try to ventilate the patient in a prone position as it has clinical importance in ventilation and oxygenation.

Effect of adding ketorolac to intravenous morphine patient-controlled analgesia on bowel function in colorectal surgery patients--a prospective, randomized, double-blind study.

BACKGROUND: Postoperative ileus (PI) is the transient impairment of bowel motility due to surgical trauma and the associated physiological responses. Postoperative ileus results in patient discomfort, increases gastrointestinal risks, prolongs hospital stay and increases medical expenses. In this study, we investigated the effect of patient-controlled analgesia (PCA) morphine with or without ketorolac on bowel functions in patients after colorectal surgeries. METHODS: A total of 79 patients who received elective colorectal resection were randomly allocated into two groups receiving either intravenous PCA morphine (M group) or intravenous PCA morphine plus ketorolac (K group). Recovery of bowel functions (bowel movement, passage of flatus, and soft diet intake), pain scores, morphine consumption, time for first ambulation, and opioid-related side-effects were recorded. RESULTS: Patients in the K group received 29% less morphine than patients in the M group with comparable pain scores. The first bowel movement (1.5 [0.7-1.9] vs. 1.7 [1.0-2.8] days, P < 0.05) and the first ambulation (2.2 +/- 1.0 vs. 2.8 +/- 1.2 days, P < 0.05) were significantly earlier in the K group than in the M group. The time of the first flatus passing, the first intake of soft diet, and duration of hospital stay were not significantly different between the two groups. CONCLUSIONS: The results of this study suggest that addition of ketorolac to intravenous morphine PCA provides an opioid-sparing effect but has limited benefit in shortening the duration of bowel immobility and time to first ambulation. These findings imply that postoperative ileus is attributable to multiple factors in addition to morphine consumption.

Suspected anaphylactoid shock to aminocaproic acid (plaslloid) during operation.

Epsilon-aminocaproic acid (plaslloid) is one of the most common hemostatics used perioperatively. Although some minor untoward effects in association with its use are not uncommon, the incidence of anaphylactoid shock is extremely rare, especially in a patient under general anesthesia. Recently we came across a severe anaphylactoid reaction, possibly as a result of administration of plaslloid in a patient who was undergoing elective surgery for cervical carcinoma. It was manifested by profound hypotension, tachycardia, hypoxemia, skin-wheel eruption and conjunctival and labial edema. She was successfully resuscitated with prompt volume expansion and epinephrine injection. Our experience in the management of this patient is, hereunder, reported and discussed.

Spectral analysis of systemic arterial pressure and heart rate signals of patients with acute respiratory failure induced by severe organophosphate poisoning.

OBJECTIVE: Spectral analysis of systemic arterial pressure (BP) and heart rate (HR) signals may be an alternative prognostic tool for predicting patient outcome in the intensive care unit (ICU). We evaluated the applicability of the same analysis in the emergency department for predicting mortality in patients with acute respiratory failure induced by severe organophosphate poisoning. DESIGN: Prospective collection of data from 14 emergency service patients. SETTING: Emergency service at a large, university-affiliated medical center. PATIENTS: Consecutive patients who, after attempting suicide by ingesting organophosphates, were admitted to the ICU of the emergency service with acute respiratory failure and remained for > or =2 days INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Demographic and survival data and day 1 Acute Physiology and Chronic Health Evaluation (APACHE) II and Glasgow Coma Scale scores were recorded. Continuous, on-line, real-time spectral analysis of BP and HR signals was carried out during the first 12 hrs after admission. We then computed the total sum of power density during this period of the low-frequency (0.04-0.15 Hz) and very low-frequency (0.004-0.04 Hz) components in the BP and HR spectra, along with the averaged values of mean BP and HR. Eight patients who recovered exhibited vigorous power in the low-frequency and very low-frequency components of their BP and HR signals. There was a significant reduction in the power density of those four spectral components in three patients who eventually died. Three patients discharged in a vegetative state manifested significantly reduced power in the low-frequency component in their BP spectra, with maintained power in the other three spectral components. APACHE II and Glasgow Coma Scale scores of the recovered patients were discernibly different from those of patients who eventually died or who became vegetative. None of the 14 patients showed appreciable differences in mean BP, mean HR, erythrocyte or plasma cholinesterase concentration, or atropine requirement during the first 24 hrs. CONCLUSION: The low-frequency and very low-frequency components of BP and HR signals may be a sensitive alternative index for early prediction of mortality in patients with acute respiratory failure induced by severe organophosphate poisoning.

Oral clonidine premedication preserves heart rate variability for patients undergoing larparoscopic cholecystectomy.

BACKGROUND: Clonidine has been shown to reduce perioperative circulatory instability. This postoperative analgesic effect of clonidine was also known in previous studies. The aim of the study was to investigate the clinical efficiency of oral clonidine premedication in anesthesia and analgesia in patients undergoing laparoscopic cholecystectomy. METHODS: Thirty-two patients scheduled for elective laparoscopic cholecystectomy were recruited for a prospective, randomized, double-blinded comparative study. They were allotted randomly to two groups: placebo or clonidine. Patients in the placebo group (n = 16) were premedicated with oral antacid (alugel hydroxide 300 mg), while those in the clonidine group (n = 16) were premedicated with oral clonidine 150 micro g before anesthesia. Analysis of heart rate variability was used to quantify the control of heart rate at baseline, and during the pneumoperitoneum and recovery periods. Time of the first request for postoperative analgesic and cumulative analgesic requirements in 24 h were recorded. Data are expressed as mean +/- SD. RESULTS: Heart rate variability was reduced in the pneumoperitoneum and postoperative period in the placebo group. Clonidine resulted in a greater perioperative (pneumoperitoneum period) power at all frequency ranges compared with placebo (671.5 +/- 470.5 vs. 55.1 +/- 51.6 ms2/Hz for total power variability, 170.1 +/- 94.4 vs. 16.9 +/- 21.1 ms2/Hz for low-frequency variability and 206.1 +/- 95.7 vs. 16.4 +/- 15.1 ms2/Hz for high-frequency variability, P < 0.05). The postoperative analgesic requirement was less (2.3 +/- 0.8 vs. 3.2 +/- 1.2 dose, P < 0.05) in comparison with the placebo group. CONCLUSION: Clonidine preserves heart rate control in pneumoperitoneum and recovery periods. Oral clonidine premedication also reduces the requirement for postoperative analgesia.

Spectral analysis of systemic arterial pressure and heart rate signals as a prognostic tool for the prediction of patient outcome in the intensive care unit.

OBJECTIVES: To evaluate the applicability of changes in spectra of systemic arterial pressure and heart rate signals in the prediction of patient outcome in an adult intensive care unit (ICU). To compare the prognostic predictability of this method with the Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring system. DESIGN: Prospective data collection from 52 ICU patients. SETTING: Adult ICU at a large, university-affiliated, medical center. PATIENTS: Consecutive patients who were admitted to the adult ICU due to noncardiac emergencies, and who remained for at least 2 days. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The demographic data, diagnosis, and survival data were recorded for each patient enrolled in this study. For the period between admission and 24 hrs before discharge, the APACHE II score was tabulated daily. Likewise, continuous, on-line, and real-time spectral analysis of systemic arterial pressure and heart rate signals was carried out every day for at least 30 mins at 2200 to 2400 hrs. The averaged power density values during this 30-min recording period of the high-frequency (0.15 to 0.4 Hz), low-frequency (0.08 to 0.15 Hz), and very low-frequency (0.016 to 0.08 Hz) components of systemic arterial pressure and heart rate signals were subsequently computed. Systemic vascular resistance index and cardiac index were also determined daily. We observed a trend of changes in the spectral components of systemic arterial pressure and heart rate signals in patients who eventually survived (n = 25) or died (n = 27). Progressive increases in the power density values of both the low-frequency and very low-frequency components of systemic arterial pressure and heart rate signals appeared to be related to recovery. Conversely, progressive decreases in the power density values of these spectral components was indicative of deterioration and fatality. The predicted outcome based on the trend of changes in the low-frequency and very low-frequency components of systemic arterial pressure and heart rate signals correlated positively with daily APACHE II scores. No direct correlation, however, was indicated by mean systemic arterial pressure, heart rate, systemic vascular resistance index, and cardiac index. We also confirmed that the differential trend of spectral changes in patients who survived or died was not due to circadian rhythm, nor alterations in the responsiveness of the blood vessels to intravenous infusion of dopamine. CONCLUSION: Power spectral analysis of systemic arterial pressure and heart rate signals offers a reasonable means of monitoring acute, critically ill patients, and may be used as an alternative prognostic tool for the prediction of patient outcome in the ICU.

Abdominal vascular injury during lumbar disc surgery.

Major vascular injury is an unusual but well-recognized complication of vertebral disc surgery. Isolated arterial laceration is the most common type of this vessel injury in lumbar spine surgery, with early manifestation due to retroperitoneal hemorrhage. Two cases are described that illustrate the full spectrum of acute manifestation of such injuries. Two cases of acute hemorrhage due to arterial trauma were seen; one mortality case was recognized during the operation and one salvaged in the recovery room. In both cases unstable perioperative hemodynamics and postoperative distended abdomen were observed. It is the purpose of this paper to report two cases and to discuss the morbid anatomy, diagnosis of such vascular injuries and anesthetic handling of retroperitoneal hemorrhage. For anesthesiologists who are also drill workers while doing lumbar spinal or epidural anesthesia, these rare catastrophes remind us to pay special attention to the vertebral vascular (not only skeletal) anatomy.

Perioperative plasma concentrations of tumor necrosis factor-alpha and interleukin-6 in infected patients.

OBJECTIVE: To characterize the sequential plasma concentrations of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) and their relationship with the clinical outcome in patients with intra-abdominal infection who underwent surgical intervention. DESIGN: A prospective, comparative study. SETTING: Surgical intensive care unit of a university hospital. PATIENTS: Fifteen patients with surgically proved intra-abdominal infection were included as the infected group. The comparative noninfected group consisted of ten patients who underwent major abdominal surgery without infection. INTERVENTIONS: Blood samples were obtained from the indwelling arterial catheter before induction of general anesthesia, and 1, 1.5, 2, 3, 4, 6, and 24 hrs after skin incision. MEASUREMENTS AND MAIN RESULTS: Plasma cytokine concentrations were measured using radioimmunoassay. The hemodynamic and physiologic parameters were recorded for comparison with cytokine concentrations. In the noninfected group, the TNF-alpha concentration was very low throughout the observation period, and the IL-6 concentration increased 4 hrs after skin incision. The infected group had significantly higher TNF-alpha and IL-6 concentrations than the noninfected group. The TNF-alpha concentration increased from 129.2 +/- 46.4 to 1196.0 +/- 445.8 pg/mL and the IL-6 concentration increased from 54.2 +/- 24.3 to 560.3 +/- 187.5 pg/mL 2 hrs after skin incision in the infected group. The postoperative APACHE II score correlated significantly with both peak IL-6 (r2=.39) and peak TNF-alpha (r2=.32) concentrations. CONCLUSIONS: Both TNF-alpha and IL-6 concentrations increased significantly after surgical intervention in patients with intra-abdominal infection. The pulse increase in TNF-alpha concentration and the persistent increase in IL-6 concentration were related to the poor postoperative clinical condition in infected patients.

Diminished vasomotor component of systemic arterial pressure signals and baroreflex in brain death.

We compared the cardiovascular autonomic regulatory mechanisms between patients with brain death or under a persistent vegetative state and healthy volunteers, based on auto- and cross-spectral analysis of systolic blood pressure (SBP) and interpulse interval (PPI) signals. Brain-dead patients exhibited a significant reduction in the absolute and relative power of the low-frequency (LF; 0.04-0.15 Hz) component in both SBP and PPI spectra, along with appreciable decrease in the very low frequency (VLF; 0.004-0.04 Hz), LF, and high-frequency (HF; 0.15-0.4 Hz) power of the PPI signals. Patients in a persistent vegetative state exhibited a power of the VLF and LF component in the SBP spectrum that was comparable to that in healthy subjects, although a discernible reduction in the VLF, LF, and HF power of the PPI spectrum was manifested by the former group. Assessments with the magnitude of SBP-PPI transfer function and linear regression analysis of beat-to-beat fluctuations in SBP and PPI revealed a progressive decline in spontaneous baroreflex sensitivity from healthy subjects to patients in a persistent vegetative state or with brain death. We conclude that the vasomotor component of systemic arterial pressure signals and spontaneous baroreflex are highly correlated with the functional integrity of the brain stem.

Tumor necrosis factor gene polymorphism and septic shock in surgical infection.

OBJECTIVES: To evaluate the relationship of the genotype distribution of the tumor necrosis factor (TNF)-alpha polymorphism with regard to the plasma TNF-alpha concentration and the development of septic shock as well as mortality of infected patients in a surgical intensive care unit (SICU). DESIGN: A total of 112 postoperative critically ill infected patients were prospectively enrolled. SETTING: SICU of a tertiary university-affiliated medical center. PATIENTS: Patients who were consecutively admitted to the SICU because of surgical infection with sepsis. INTERVENTION: Blood sampling. MEASUREMENTS AND MAIN RESULTS: Blood sample was obtained 24 hrs after intensive care unit (ICU) admission or within 2 hrs after the onset of septic shock to determine the plasma TNF-alpha level and to analyze the genotype of the biallelic polymorphism of the TNF-alpha. RESULTS: The allele frequency of the TNF2 in our infected ICU patients was 12%. Forty-two (37.5%) patients admitted fulfilled the criteria of septic shock during their ICU stay. Patients carrying the TNF2 allele were not more likely to develop septic shock, nor did they have a higher mortality rate. In the patients with septic shock, those carrying the TNF2 allele had a significantly higher mortality rate than those with the homozygous TNF1 genotype (92% vs. 62%, p < .05). In those who developed septic shock, the TNF2 allele was significantly associated with higher TNF levels. CONCLUSION: In patients admitted to SICU with surgical infection, the frequency of TNF2 allele was higher than in the general population. SICU patients with TNF2 allele did not show a higher incidence of developing septic shock, nor was there a higher baseline TNF-alpha level after infection. However, once septic shock had developed, the mortality rate was higher in those patients carrying the TNF2 allele.