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PubMed1995

Shivering and rewarming after cardiac surgery: comparison of ventilator circuits with humidifier and heated wires to heat and moisture exchangers.

BACKGROUND: Detrimental physiologic effects of shivering in the cardiac surgery patient have been well documented. Rewarming techniques have been compared, with noted differences in the incidence of shivering. Ventilator circuits have not been examined independently from other rewarming variables. OBJECTIVE: To compare heated wire humidification circuits with heat and moisture exchanger circuits on the incidence of shivering and speed and pattern of rewarming in mechanically ventilated patients. METHODS: A prospective, descriptive, correlational study was done on 140 adult cardiac surgery patients in a university teaching medical center. All subjects underwent cardiac surgical procedures with hypothermic cardiopulmonary bypass. Subjects were randomized to humidified, heated wire circuits (n = 70) or heat and moisture exchanger circuits (n = 70). Heated water blankets were used on all patients. RESULTS: Mean intensive care unit admission temperature was 35.28 degrees C. No statistical differences were found in preoperative, demographic, or operative course data between treatment and control groups. Shivering was more common in the heat and moisture exchanger group than in the heated wire group. In our analysis, the only variable associated with shivering was the type of ventilator circuit. Patients using heated wire systems rewarmed more rapidly and had significantly higher temperatures than did patients using heat and moisture exchangers. CONCLUSION: These data suggest that use of heated wire humidified ventilator circuits with heated water blankets in adult cardiac surgery patients significantly reduces the incidence of shivering and results in a more rapid return to normothermia.

Aged↗
PubMed1993

Effect of intravenous clonidine on prevention of postepidural shivering.

The effects of intravenous clonidine, a central adrenergic alpha-2 agonist, on the incidence of shivering and hemodynamic changes after epidural anesthesia were assessed in patients undergoing extracorporeal shock wave lithotripsy (ESWL). Forty ASA class I or II patients were randomly assigned in a double-blind manner to one of two groups. Twenty patients received intravenous clonidine 150 micrograms/10 ml (clonidine group) and twenty patients received normal saline (control group) at 20 min before epidural administration of 1.5% lidocaine. Shivering was determined objectively by observing involuntary muscle activity. Arterial blood pressure, heart rate, respiratory rate and oxygen saturation were measured at 5-min intervals during the first 50 minutes following IV pretreatment. There was significant difference between clonidine and control groups in the incidence of shivering (5% vs. 55%, p = 0.002). Shivering began at an average of 16.8 +/- 9 min (range: 5-30 min) in control group and only one patient shivered at 18 min in clonidine group. The mean sensory level was T7 in both groups. There were no differences between the two groups in mean arterial pressure and respiratory rate, though there was a trend in reduction of MAP in clonidine group. Heart rate and oxygen saturation decreased slightly in clonidine group. The main adverse effect of clonidine pretreatment was drowsiness. In conclusion, intravenous clonidine 150 micrograms was effective in preventing shivering with minor hemodynamic changes in patients receiving epidural anesthesia.

Adult↗
PubMed1998

[Analysis of postoperative shivering following the deliberate mild hypothermia during neurosurgery].

We induced deliberate mild hypothermia in 96 patients who underwent intracranial operations using a water blanket and a convective device blanket. The lowest temperature measured at the tympanic membrane during mild hypothermia was adjusted to 34.5 degrees C. The patients were divided into two groups in respect to the occurrence of postoperative shivering, and the relationship between the perioperative parameters and the occurrence of postoperative shivering was evaluated. Shivering was observed postoperatively in 29 to 96 patients (30.2%). In the group with shivering (SV), age was significantly lower and body weight and body surface area were significantly larger than the group without shivering (NSV). Urinary output was significantly larger in SV than in NSV. Tympanic membrane, nasopharyngeal, and rectal temperatures at the end of surgery and nasopharyngeal, rectal, and peripheral temperatures just after the extubation were significantly lower in SV than in NSV. These results suggest that sufficient rewarming of both the core and peripheral temperatures is important to prevent the postoperative shivering following the mild hypothermic therapy in neurosurgical patients, especially in young patients.

Adult↗
PubMed1985

Oligodendroglial structures and distribution shown by carbonic anhydrase immunostaining in the spinal cords of developing normal and shiverer mice.

The spinal cords of young and adult normal and dysmyelinating mutant (shiverer) mice were immunostained with anticarbonic anhydrase to investigate the distribution of oligodendroglial populations into the gray- and white-matter regions in the developing normal and mutant animals; the morphology of oligodendrocytes and their processes at the light microscopic level in gray matter and white matter; and the apparent gliosis in the gray matter, as well as the white matter, of the mutants. Immunocytochemistry and enzyme assays revealed consistent increases in carbonic anhydrase antigenicity and specific activity in controls and mutants between the ages of approximately 15 days and approximately 60 days. As shown previously in adult animals, oligodendroglia in larger than normal proportions were situated at the periphery of the "white-matter" columns, as compared to gray matter, in the shiverers, with, however, significant numbers of oligodendroglia were heterogeneous with respect to shapes, configuration of processes, and intensity of carbonic anhydrase immunostaining. In the shiverer "white matter" the oligodendrocytes were smaller than normal, and their shapes and arrangement were relatively irregular. In the normal gray matter short oligodendroglial processes appeared to be associated with neuronal perikarya, and those processes were more pronounced at approximately 90 days than at approximately 20 days of age. Background staining in normal gray matter suggested that oligodendroglial processes were, in addition, tightly wound around many axons. In shiverer gray matter the oligodendrocytes were smaller, and their processes appeared to be wrapped more loosely around smaller numbers of conspicuous axons and to be associated less frequently with neuronal perikarya. This finding suggests that the deficiency in the myelin basic protein in the mutant may affect interactions between oligodendrocytes and neurons in the gray matter as well as in the white matter. The astrocytic "marker," glial fibrillary acidic protein, was detected in gray and white matter of shiverers as young as 16 days, and the differences from carbonic anhydrase localization supported the conclusion that the processes enwrapping axons in the shiverer mouse CNS are derived from oligodendrocytes, not astrocytes.

Age Factors↗
PubMed1990

Characteristic changes between core and peripheral surface temperature related with postanesthetic shivering following surgical operations.

The relationship between changes in the core and the surface temperature and postanesthetic shivering was studied in 100 patients who underwent general anesthesia. Patients were classified into four groups by the patterns of change in the core and peripheral surface temperature. Type II and type IV groups of patients showed a decrease in surface temperature during the major operation such as gastrectomy and radical mastectomy. Type I and type III groups of patients showed no lowered peripheral surface temperature and with low temperature difference between core and surface temperature during the operation. The patients in type II and IV groups showed increased difference between core and surface temperature. The postanesthetic shivering occurred at significantly higher rate compared to the other two groups. As possible reasons of the shivering, operation of long duration and insufficient circulating blood volume were considered. Shivering reduces the temperature difference in the thermoregulatory homeostasis. However, in patients in type I and III, the rate of shivering was low. Evaluation of the difference between core and peripheral surface temperature may be important to manage body temperature at a steady level during the operation. The monitoring of body temperature difference between core and peripheral surface during the operation may be useful for predicting to occurrence of postanesthetic shivering.

Journal Article↗
PubMed1983

Distribution of myelin-associated enzymes and myelin proteins into membrane fractions from the brains of adult shiverer and control (+/+) mice.

Shiverer, an autosomal recessive mutation in the mouse, is characterized by a severe deficiency in CNS myelin. The concentrations of the myelin basic and proteolipid proteins in the brains of two-month-old shiverer mice, although high enough to be measured, were much lower than in the control (+/+) brains. In contrast, the specific activities of the myelin-associated enzymes, 2',3'-cyclic nucleotide-3'-phosphohydrolase (CNP), 5'-nucleotidase, and carbonic anhydrase, were close to normal in the brains of the mutants. The activities of these enzymes and the concentrations of the myelin large basic and proteolipid proteins were compared in membrane fractions prepared, by differential and density gradient centrifugation, from the brains of shiverer and +/+ control mice. In myelin purified from the brains of shiverer mice the specific activities of 5'-nucleotidase and CNP were close to normal, and the specific activities of all three enzymes were normal in a crude myelin fraction from brains of the mutants. However, in the shi/shi brains abnormally high proportions of the three myelin-associated enzymes were distributed into the P3 (microsomal) fraction and into membrane fractions denser than myelin. The major myelin proteins, although low in total amounts in the mutants' brains, were distributed into the membrane fractions from control and shiverer brains in relative proportions similar to the relative proportions observed for the three enzymes. Thus, carbonic anhydrase, 5'-nucleotidase and CNP in the brains of shiverer mice are not truly dissociated from the major myelin proteins but are, rather, distributed for the most part into the same populations of membranes as are the residual, small amounts of the myelin basic and proteolipid proteins.

5'-Nucleotidase↗
PubMed1986

Shiverer jimpy double mutant mice. I. Biochemical evidence for reciprocal intergenic suppression.

Shiverer and jimpy are neurological mutations that cause hypomyelination in the mouse CNS. The 3 major protein components of CNS myelin are: myelin basic protein (MBP), proteolipid (PLP) and 2', 3'-cyclic nucleotide phosphohydrolase (CNP). Previous work has shown that in jimpy animals the CNS contains reduced levels of MBP and CNP while PLP is undetectable. In shiverer animals the major forms of MBP ae undetectable in either the CNS or PNS, but the level of CNP is unaffected by mutation. In this study we have measured MBP, PLP and CNP in both the CNS (cerebral hemispheres) and PNS (sciatic nerve) of mice carrying the jimpy and shiverer mutations, individually and in combination. The results indicate that in the double mutant the levels of all 3 myelin proteins in both the CNS and PNS are intermediate between the levels in jimpy and the levels in shiverer animals. This means that part of the biochemical phenotype of the jimpy mutation (reduced levels of CNP and absence of PLP) is suppressed by the shiverer mutation, and part of the biochemical phenotype of the shiverer mutation (absence of MBP) is suppressed by the jimpy mutation. Possible mechanisms for this reciprocal intergenic suppression are discussed.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1999

Postoperative shivering: aetiology and treatment.

Most postanaesthetic shivering-like tremor is normal thermoregulatory shivering in response to core hypothermia. Therefore, shivering will be prevented by maintaining intraoperative normothermia. Other thermoregulatory-related shivering is caused by the release of cytokines by the surgical procedure. Non-thermoregulatory shivering, occurring in normothermic patients, is caused by other aetiologies such as postoperative pain. It is thus likely that adequate treatment of postoperative pain will ameliorate non-thermoregulatory tremor. In addition, the administration of antipyretic drugs reduces shivering in patients after cardiopulmonary bypass surgery.

Journal Article↗
PubMed1980

Subcellular distribution and developmental change of 2',3'-cyclic nucleotide 3'-phosphohydrolase in the central nervous system of the myelin-deficient shiverer mutant mice.

Shiverer is an autosomal recessive mutant characterized by dysmyelination in the central nervous system. The myelin in the shiverer is devoid of the major dense line. The pattern of increase of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) in the various parts of central nervous system during postnatal development was identical with that of controls. Subcellular fractionation of the brain from shiverer showed that the recovery of CNPase activity of the P2A was only 14% of the control, but those of P2B and P3 were several times higher than the controls. The specificity activity of CNPase of the purified myelin and P2A from shiverer did not differ significantly from that of the controls. The combined P2 and P3 (P2 + P3) fraction was subjected to linear sucrose density gradient (0.32--1.3 M) centrifugation. By measuring CNPase activities of the fractions obtained after centrifugation, shiverer showed two peaks of CNPase activities in the sucrose gradient, although that of the control showed a single peak. The main peak obtained from shiverer was found in the region of higher sucrose concentration than that of the control, while a small peak was found in the region of lower sucrose concentration.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1982

Dysmyelination of shiverer mutant mice in vivo and in vitro.

Demyelination in the CNS of shiverer mutant mice was studied in vivo and in vitro. By immunohistochemical reaction with glial fibrillary acidic protein antibody, hypertrophy of the fibrous astrocytes was observed in the white matter of shiverer cerebella. The cerebella of shiverer mice in primary culture from the day of birth showed very poor myelination under optical microscopy. Axons of Purkinje cells are thought to be the main myelinated axons in the primary culture of the cerebellum. Purkinje cells from shiverer appeared normal with regard to Bodian silver impregnation, hematoxylin and eosin staining, and P400 protein characterization of Purkinje cells. Addition of the conditioned culture medium of shiverer to the control culture did not interfere with myelination. We concluded that the demyelination in the CNS of shiverer could be caused by an intrinsic defect of the oligodendrocyte rather than by hypertrophy of the astrocytes or by diffusible factors.

Animals↗
PubMed1994

Restoration of brain stem auditory-evoked potentials by gene transfer in shiverer mice.

We studied the shiverer mouse as a model for correcting hearing disorders resulting from genetic abnormalities of the central nervous system (CNS). Shiverer mice are homozygous for an autosomal recessive mutation (deletion) in the gene for myelin basic protein (MBP), a major protein component of the myelin sheath in the CNS. Under electron microscopic observation of the cochlear nerve, the CNS portion in shiverer mice showed hypomyelination, but the peripheral portion, including spiral ganglion cells, was normal. We produced MBP-transgenic mice by microinjection of an MBP cosmid clone into the pronucleus of fertilized eggs from shiverer mice. The transgenic mice were found to recover MBP levels up to 25% of normal. A greater number of axons in the transgenic mice were myelinated than in the shiverer mice, but the myelin sheath was not as thick as in normal controls. Every interpeak latency of brain stem auditory-evoked potentials was prolonged in the shiverer mice and improved in the transgenic mice. This study provides an example of gene therapy for hearing disorders caused by a CNS abnormality. We discuss some strategies for researching genetic hearing impairment or deafness in both animals and humans.

Animals↗
PubMed1989

Morphometric and freeze-fracture studies on peripheral nerve in shiverer mice.

Observations have been made on the peripheral nerves of shiverer (shi/shi) mice in comparison with control animals. Although this mutant lacks P1 myelin basic protein in peripheral and central myelin, myelin is defective only in the central nervous system. No ultrastructural abnormalities were observed in the shiverer nerves. Myelin spacing was normal. The density and distribution of intramembranous particles on the E and P faces of myelin and in the axolemma of myelinated and unmyelinated axons did not differ between the shiverer and control mice. Morphometric studies showed that external myelinated fiber diameter was significantly less and that myelin thickness was slightly but significantly greater in relation to axon diameter in the shiverer mice, suggesting a minor degree of axonal atrophy. It is concluded that P1 protein is not necessary for the formation and maintenance of the normal structure of peripheral myelin. The failure to detect differences in intramembranous particle density in myelin between shiverer and control mice indicates that P1 protein is not detected in freeze-fracture preparations.

Animals↗
PubMed1984

Respiratory responses to shivering produced by external and central cooling in the pigeon.

Respiratory responses of pigeons to spinal cord cooling (5-6 degrees C) in neutral environment (Ta = 28 degrees C), to ambient cooling (Ta = 5 degrees C), and to simultaneous spinal cord and ambient cooling were measured. Spinal cord cooling produced shivering and a 242% increased in heat production (M); expiratory flow rate (VE) increased 216%, a result of increases in both respiratory frequency (160%) and tidal volume (140%). Increases produced by ambient cooling compared to thermoneutral controls were slightly, but not significantly, less than those during spinal cord cooling: M = 203%, VE = 199%, respiratory frequency (fR) = 146%, tidal volume (VT) = 138%. Spinal cord cooling at low ambient temperature produced greater increases in shivering, heat production and respiration compared to thermoneutral controls than either type of cooling alone: M = 337%, VE = 326%, fR = 198%, VT = 178%. The oxygen extraction from the ventilatory gas remained relatively constant among the different groups. fR, VT and VE were all significantly linearly related to M over the wide range studied. These relationships were independent of whether cooling was central or external. Respiratory changes induced by the onset and end of spinal cord cooling were immediate and closely correlated with the magnitude of shivering. It is unlikely that changes in arterial and venous blood gases during shivering effected the major portion of the respiratory response. Thus, it is suggested that a control mechanism of the respiratory center via afferents from the shivering muscles is important in increasing respiration during central or external cooling.

Animals↗
PubMed1988

The effects of shivering on oxygen consumption and carbon dioxide production in patients rewarming from hypothermic cardiopulmonary bypass.

Oxygen consumption (VO2), carbon dioxide production (VCO2), end-tidal carbon dioxide partial pressure (PETCO2), mixed venous oxygen saturation (SvO2) and haemodynamic variables were recorded every 30 min for four hours in 15 patients recovering from hypothermic cardiopulmonary bypass (CPB). All patients had been anaesthetised with fentanyl 40 micrograms.kg-1, supplemented with isoflurane, and pancuronium 0.15 mg.kg-1 for muscle relaxation. Three of the 15 patients (20 per cent) shivered, defined as intermittent or continuous, vigorous movements of chest or limb muscles. Patients who shivered had a VO2 of 159 +/- 16.4 ml.min-1.m-2 on arrival in the ICU which rose to a maximum value of 254 +/- 28.3 ml.min-1.m-2 by 150 min post-CPB. In contrast, patients who did not shiver had a significantly lower VO2 of 93.1 +/- 6.9 ml.min-1.m-2 on arrival in the ICU which rose to a maximal value of only 168 +/- 11.5 ml.min-1.m-2 by 180 min post-CPB. Maximal VO2 in both groups was reached when the nasopharyngeal temperature (NPT) was approaching normal. VCO2 paralleled the increase in VO2 in both groups. By four hours there was no significant difference between the two groups; however, the VO2 in both groups (160.5 +/- 21.3 ml.min-1.m-2 and 173.9 +/- 12.3 ml.min-1.m-2 respectively) was approximately twice values commonly measured in anaesthetized patients. Patients who shivered had a significantly higher heart rate and cardiac index and significantly lower SvO2. We conclude that the high VO2 and VCO2 associated with shivering causing increased myocardial work may be detrimental to patients who have impaired cardiac function post-coronary artery surgery (CAS).

Aged↗
PubMed1997

Clonidine at induction reduces shivering after general anaesthesia.

PURPOSE: Postanaesthetic shivering occurs in 5-65% of patients. In addition to causing discomfort, it is associated with deleterious consequences. Our objective was to investigate the effect of 150 micrograms clonidine, at induction of anaesthesia, on perioperative core and peripheral temperature, incidence of postanaesthetic shivering and patients' perception of cold. METHODS: Sixty ASA 1 or 2 patients scheduled for elective orthopaedic limb surgery were randomly allocated to group 1, who received 150 micrograms clonidine iv, or group 2, who received a saline bolus iv, before induction. In all patients, anaesthesia was induced with fentanyl and propofol and maintained by spontaneous respiration (via a laryngeal mask airway) of oxygen, nitrous oxide and enflurane. Core (nasopharyngeal) and peripheral (dorsal hand) temperatures were recorded at induction and 15-min intervals. Nurses, unaware of the treatment groups, recorded visible shivering in the recovery room. When cognitive function returned, patients were asked to grade their perception of cold on a 10 cm linear analogue scale, higher scores indicating heat discomfort. RESULTS: While core temperature decreased and peripheral temperature increased in both groups, there was no difference between the groups at any time. However, there was a lower incidence of shivering in the clonidine group (20% vs 66.7%, P < 0.001). Patients receiving clonidine felt warmer; thermal comfort score (median interquartile range) 5.9 (5.0-7.2) vs 5.0 (4.5-6.0), P < 0.05). CONCLUSION: Clonidine 150 g iv at induction of anaesthesia reduces the incidence of shivering and patients' subjective perception of cold on emergence from general anaesthesia.

Adolescent↗
PubMed2007

[Dolasetron and shivering. A prospective randomized placebo-controlled pharmaco-economic evaluation].

BACKGROUND AND GOAL: Forced by the current economical situation, German hospitals have to reconsider their clinical productivity. When caregivers introduce new therapeutic concepts medical quality should either be improved without increasing costs or when reducing costs medical quality should be maintained. In the surgical field postoperative shivering reduces both patient comfort and medical quality. We therefore investigated the clinical pathway prevention of shivering with dolasetron in a prospective, randomized, placebo-controlled analysis of cost-effectiveness. MATERIAL AND METHODS: After written informed consent we randomized 40 patients scheduled for lumbar disc hernia repair or head and neck surgery into two groups: patients of group D received dolasetron 1 mg/kg body weight during surgery whereas patients of group K received 100 ml saline as placebo. Primary endpoints were the incidence of shivering, the length of stay in the postanesthesia care unit and process-associated costs. Secondary endpoint was the influence on perioperative thermoregulation. RESULTS: We observed postanesthetic shivering in 5 patients belonging to group D in comparison to 15 patients receiving the placebo (p<0.05). The length of stay in the postanesthesia care unit was shorter in patients allocated to dolasetron (mean+/-SD; group D: 43+/-16 min, group K 62+/-18 min, p<0.05). There was a significant saving in process-associated personnel costs (personnel costs in group D EUR 41.26+/-14, personnel costs in group K EUR 53.15+/-15) but in contrast the process-associated material costs were significantly increased (group D EUR 17.16+/-3, group K EUR 0.73+/-1, p<0.05). CONCLUSIONS: The optimization of the clinical process and medical quality induced by a prophylaxis against shivering and postoperative nausea and vomiting compensates for the increased use of pharmaceutical resources in our setting.

Adolescent↗
PubMed1994

Effect of clonidine on postpartum shivering after epidural analgesia: a randomized, controlled, double-blind study.

In obstetric patients treated with epidural analgesia during labor and delivery, shivering is quite frequent due to stress, vasodilatation, infusion of fluids, low ambient temperature, and the direct effect of solution injected into the epidural space. Sixty obstetric patients who developed shivering after receiving epidural analgesia for delivery were randomly assigned to treatment with clonidine 0.150 mg i.v. (N = 20), meperidine 50 mg i.v. (N = 20), or saline solution (N = 20). Drug administration was double blind. The effect on shivering (graded as all or none), drowsiness, heart rate, and systolic arterial pressure was evaluated 5 min after the study drug was administered. Clonidine was as effective as meperidine in controlling shivering and caused a greater reduction in heart rate. Drowsiness occurred after clonidine as well as meperidine. Thus, clonidine proved to be effective in controlling shivering and adrenergic response after delivery using epidural analgesia and produced an acceptable level of drowsiness.

Adult↗
PubMed1996

The effects of forced-air warming on postbypass central and skin temperatures and shivering activity.

STUDY OBJECTIVE: To test the hypothesis that forced-air skin-surface warming used prophylactically after hypothermic cardiopulmonary bypass (CPB) would: (1) decrease the incidence and severity of postbypass shivering, (2) rapidly increase skin-surface temperatures when compared with standard warmed cotton blankets, and (3) not contribute to excessive central temperature elevation. DESIGN: Prospective, randomized, nonblinded comparison of two rewarming techniques. SETTING: Multidisciplinary intensive care unit at a tertiary care, private teaching hospital. PATIENTS: Following hypothermic CPB, 47 patients underwent postoperative rewarming by using either conduction (warmed cotton blankets) or convection (forced-air cover) techniques. MEASUREMENTS AND MAIN RESULTS: Central and skin temperatures were measured at 30-minute intervals for 5.5 hours postoperatively. Four lead electromyographic recordings were used to objectively document shivering activity. Antihypertensives, opioids, sedatives, and muscle relaxants were administered per patient need and recorded. The forced-air cover markedly decreased the overall incidence, duration, and magnitude of significant shivering compared with the warmed cotton blankets. Forced-air therapy produced clinically significant increases in skin surface temperatures, but avoided excessive central temperature elevation when compared with passive rewarming with cotton blankets. CONCLUSION: Convection warming, when compared with conductive warming with cotton blankets, limited the incidence, magnitude, and duration of shivering following hypothermic cardiac surgery. This suggests an important role of cutaneous thermal input in the mediation of the shivering response. The central tissue compartment is buffered from the effects of skin-surface warming and, thus, forced-air therapy will not lead to excessive central temperature elevation in this patient population when compared with cotton blanket rewarming.

Aged↗