Depressed Reflexes Research Articles

Membrane fluidity does not explain how solvents act on the middle-ear reflex

Some volatile aromatic solvents have similar or opposite effects to anesthetics in the central nervous system. Like for anesthetics, the mechanisms of action involved are currently the subject of debate. This paper presents an in vivo study to determine whether direct binding or effects on membrane fluidity best explain how solvents counterbalance anesthesia’s depression of the middle-ear reflex (MER). Rats were anesthetized with a mixture of ketamine and xylazine while also exposed to solvent vapors (toluene, ethylbenzene, or one of the three xylene isomers) and the amplitude of their MER was monitored. The depth of anesthesia was standardized based on the magnitude of the contraction of the muscles involved in the MER, determined by measuring cubic distortion product oto-acoustic emissions (DPOAEs) while triggering the bilateral reflex with contralateral acoustic stimulation. The effects of the aromatic solvents were quantified based on variations in the amplitude of the DPOAEs. The amplitude of the alteration to the MER measured in anesthetized rats did not correlate with solvent lipophilocity (as indicated by logKow values). Results obtained with the three xylene isomers indicated that the positions of two methyl groups around the benzene ring played a determinant role in solvent/neuronal cell interaction. Additionally, Solid-state Nuclear Magnetic Resonance (NMR) spectra for brain microsomes confirmed that brain lipid fluidity was unaffected by solvent exposure, even after three days (6h/day) at an extremely high concentration (3000ppm). Therefore, aromatic solvents appear to act directly on the neuroreceptors involved in the acoustic reflex circuit, rather than on membrane fluidity. The affinity of this interaction is determined by stereospecific parameters rather than lipophilocity.

Lambert–Eaton myasthenic syndrome: Clinical review

AbstractLambert–Eaton myasthenic syndrome (LEMS) is an autoimmune disease of the neuromuscular junction and approximately 60% of LEMS patients have a tumor, mostly small cell lung cancer, as a paraneoplastic neurological syndrome. LEMS patients develop a unique set of clinical characteristics, which include proximal muscle weakness, depressed tendon reflexes with post‐tetanic potentiation and autonomic symptoms. Interestingly, slightly <10% of LEMS patients have cerebellar ataxia (LEMS with paraneoplastic cerebellar degeneration). Considering its pathomechanism, LEMS is a presynaptic disorder of neuromuscular transmission in which quantal release of acetylcholine is impaired by autoantibodies for P/Q‐type voltage‐gated calcium channels at active zones, although an animal model by immunizing purified P/Q‐type voltage‐gated calcium channels has not yet been successful.

Hyponatremia

Hyponatremia is biochemically defined by a blood sodium concentration ([Na⁺]) below the normal reference range for the laboratory performing the test (typically &lt;135 mmol/L). The clinical relevance of a below normal blood [Na⁺] is largely determined by the severity of the clinical signs and symptoms associated with cellular swelling. Severe hyponatremia may induce seizures, coma and cardiopulmonary arrest. However, mild to moderate hyponatremia may present with more non-descript symptoms such as lethargy, restlessness, disorientation, headache, nausea and vomiting, muscle cramps, and depressed neural reflexes. Low [Na⁺] can be caused by: 1) fluid overload (hypervolemia); 2) abnormal fluid retention (euvolemia); or 3) volume depletion (hypovolemia) or some likely combination. Morbidity and mortality from hyponatremia has been documented in infants fed dilute formula, children forced to drink excessive amounts of fluid as punishment, athletes who drink excessively during exercise, compulsive water drinkers (psychogenic polydipsia), and hospitalized patients receiving excessive amounts of intravenous fluids. Poor clinical outcomes and delayed recovery have been documented in patients with hyponatremia, compared to those who maintain normonatremia. Thus, the secret stories of <i>hyponatremia</i> often whisper tales of harm (overzealous fluid ingestion or administration) with the intention of good (prevent dehydration) except in the severely deranged (child abuse) or demented (schizophrenic psychogenic polydipsia). <b>ABBREVIATIONS:</b>[Na⁺] – sodium concentration, ADH - anti-diuretic hormone, AVP – arginine vasopressin, EAF - exercise associated hyponatremia, ECF – extracellular fluid, RAAS - renin-angiotensin-aldosterone system, SIADH - syndrome of anti-diuretic hormone secretion

Is there an association between altered baroreceptor sensitivity and obstructive sleep apnoea in the healthy elderly?

Obstructive sleep apnoea (OSA) is associated with a rise in cardiovascular risk in which increased sympathetic activity and depressed baroreceptor reflex sensitivity (BRS) have been proposed. We examined this association in a sample of healthy elderly subjects with unrecognised OSA.801 healthy elderly (aged ≥65 years) subjects undergoing clinical, respiratory polygraphy and vascular assessment were examined. According to the apnoea–hypopnoea index (AHI), the subjects were stratified into no OSA, mild–moderate OSA and severe OSA cases.OSA was present in 62% of the sample, 62% being mild–moderate and 38% severe. No differences were found for BRS value according to sex and OSA severity. 54% of the group had normal BRS value, 36% mild impairment and 10% severe dysfunction. BRS was negatively associated with body mass index (p=0.006), 24-h systolic (p=0.001) and diastolic pressure (p=0.001), and oxygen desaturation index (ODI) (p=0.03). Regression analyses revealed that subjects with lower BRS were those with hypertension (OR 0.41, 95% CI 0.24–0.81; p=0.002) and overweight (OR 0.42, 95% CI 0.25–0.81; p=0.008), without the effect of AHI and ODI.In the healthy elderly, the presence of a severe BRS dysfunction affects a small amount of severe cases without effect on snorers and mild OSA. Hypertension and obesity seem to play a great role in BRS impairment.

Clinical diagnosis of upper lumbar disc herniation: Pain and/or numbness distribution are more useful for appropriate level diagnosis.

The purpose of this study is to disclose the characteristic symptoms and signs in L2, L3 and L4 nerve root disturbance. Fifty eight patients who underwent lateral herniotomy were analyzed. Breakdowns are 15 patients with L2/3 lateral disc herniation (group A), 20 patients with L3/4 lateral disc herniation (group B), and 23 patients with L4/5 lateral disc herniation (group C). The following items were examined: 1) localization of the subjective pain and numbness, 2) objective neurological findings, including deep tendon reflex, manual muscle strength (MMT), straight leg raising test (SLRT) and femoral nerve stretch test (FNST). In group A, subjective pain and/or numbness was present in the thigh aspect, proximal to the knee joint in all patients. In group B, 80% of the patients had subjective pain and/or numbness in the medial site of the knee joint. In group C, the subjective pain and/or numbness was localized in various aspects of the lower extremity. Weakness in the iliopsoas, the femoral quadriceps, and the anterior tibial muscle were observed in 60-95%, 27-70%, 0-43% of three groups, respectively. Depression or absence of the patella tendon reflex was present in 27-100% of three groups. SLRT and FNST were positive in 13-87% and 91-95% of three groups. Symptomatic levels of nerve root disturbance in the upper lumbar spine could not be accurately identified by objective neurological findings alone. Pain and/or numbness localized in the thigh area proximal to the knee joint is a specific sign of L2 nerve root disturbance. Either subjective pain or numbness in the medial knee joint aspect is another key sign which strongly suggests L3 nerve root disturbance.

Sleep duration, depression, and oxytocinergic genotype influence prepulse inhibition of the startle reflex in postpartum women

The postpartum period is characterized by a post-withdrawal hormonal status, sleep deprivation, and susceptibility to affective disorders. Postpartum mothering involves automatic and attentional processes to screen out new external as well as internal stimuli. The present study investigated sensorimotor gating in relation to sleep duration, depression, as well as catecholaminergic and oxytocinergic genotypes in postpartum women.Prepulse inhibition (PPI) of the startle reflex and startle reactivity were assessed two months postpartum in 141 healthy and 29 depressed women. The catechol-O-methyltransferase (COMT) Val158Met, and oxytocin receptor (OXTR) rs237885 and rs53576 polymorphisms were genotyped, and data on sleep duration were collected.Short sleep duration (less than four hours in the preceding night) and postpartum depression were independently associated with lower PPI. Also, women with postpartum depression had higher startle reactivity in comparison with controls. The OXTR rs237885 genotype was related to PPI in an allele dose-dependent mode, with T/T healthy postpartum women carriers displaying the lowest PPI.Reduced sensorimotor gating was associated with sleep deprivation and depressive symptoms during the postpartum period. Individual neurophysiological vulnerability might be mediated by oxytocinergic genotype which relates to bonding and stress response. These findings implicate the putative relevance of lower PPI of the startle response as an objective physiological correlate of liability to postpartum depression.

Gullian- Barre Syndrome in Pregnancy – A Case Report and Review of the Literature

The immune-mediated Gullian- Barre syndrome (GBS) is an acute demyelinating polyradiculopathy (AIDP) which typically presents as progressive, fairly symmetric muscle weakness accompanied by absent or depressed deep tendon reflexes. It has been linked to various infectious agents, such as Campilobacter jejuni and typically presents 2-4 weeks following a respiratory or gastrointestinal illness. With an estimated incidence in the general population of 0.75-2:100,000, its occurrence in pregnancy does not differ. Diagnostic criteria consist of clinical, laboratory and electrophysiological tests. Treatment of pregnant and non-pregnant patients with GBS usually does not differ and it is mainly composed of supportive care and monitoring of respiratory, cardiac and hemodynamic functions. Disease modifying treatments such as plasmapheresis and intravenous immunoglobulin (IVIG) are relatively safe in pregnancy. Timing and mode of delivery are based on obstetric indications and depend on maternal and fetal status. As such, if a pre-term delivery is indicated a course of antenatal corticosteroids should be considered. Therefore, GBS in pregnancy should be handled by a multidisciplinary team involving neurologists, obstetricians and anesthesiologists. We present a case report of an otherwise healthy woman diagnosed with GBS in pregnancy. Patient presentation, diagnosis, treatment and outcome as well of review of the literature will be discussed.

Postactivation depression of the Ia EPSP in motoneurons is reduced in both the G127X SOD1 model of amyotrophic lateral sclerosis and in aged mice.

Postactivation depression (PActD) of Ia afferent excitatory postsynaptic potentials (EPSPs) in spinal motoneurons results in a long-lasting depression of the stretch reflex. This phenomenon (PActD) is of clinical interest as it has been shown to be reduced in a number of spastic disorders. Using in vivo intracellular recordings of Ia EPSPs in adult mice, we demonstrate that PActD in adult (100-220 days old) C57BL/6J mice is both qualitatively and quantitatively similar to that which has been observed in larger animals with respect to both the magnitude (with ∼20% depression of EPSPs at 0.5 ms after a train of stimuli) and the time course (returning to almost normal amplitudes by 5 ms after the train). This validates the use of mouse models to study PActD. Changes in such excitatory inputs to spinal motoneurons may have important implications for hyperreflexia and/or glutamate-induced excitotoxicity in the neurodegenerative disease amyotrophic lateral sclerosis (ALS). With the use of the G127X SOD1 mutant mouse, an ALS model with a prolonged asymptomatic phase and fulminant symptom onset, we observed that PActD is significantly reduced at both presymptomatic (16% depression) and symptomatic (17.3% depression) time points compared with aged-matched controls (22.4% depression). The PActD reduction was not markedly altered by symptom onset. Comparing these PActD changes at the EPSP with the known effect of the depression on the monosynaptic reflex, we conclude that this is likely to have a much larger effect on the reflex itself (a 20-40% difference). Nevertheless, it should also be accounted that in aged (580 day old) C57BL/6J mice there was also a reduction in PActD although, aging is not usually associated with spasticity.

Mild obstructive sleep apnea does not modulate baroreflex sensitivity in adult patients.

BackgroundObstructive sleep apnea (OSA) is a chronic and progressive disease. OSA is associated with increased cardiovascular morbidity and mortality, the risk being more frequently encountered with severe degrees of OSA. Increased sympathetic activation and impaired cardiac autonomic control as reflected by depressed baroreceptor reflex sensitivity (BRS) are possible mechanisms involved in the cardiovascular complications of OSA. However, it is not known at what stage of OSA that changes in BRS appear. The aim of this study was to evaluate BRS in patients with mild OSA.MethodsThe study population consisted of 81 overweight patients with mild OSA and 46 body weight-matched non-OSA subjects. BRS, apnea-hypopnea index, body mass index, and metabolic parameters were assessed. The phenylephrine test was used to measure BRS.ResultsPatients in the OSA group were slightly but significantly older than the non-OSA population (50.3±9.3 years vs 45.7±11.1 years, P=0.02). Body mass index, percentage body fat, blood pressure, fasting glucose, insulin, and lipid levels did not differ between the OSA patients and non-OSA subjects. Absolute BRS values in patients with mild OSA and non-OSA subjects (9.97±6.70 ms/mmHg vs 10.51±7.16 ms/mmHg, P=0.67) and BRS values proportional to age-related and sex-related reference values (91.4%±22.7% vs 92.2%±21.8%, P=0.84) did not differ from each other. BRS <50% of the sex-specific reference value was found in 6% of patients with mild OSA and in 2% of non-OSA subjects (P=0.29).ConclusionPatients with mild OSA did not show evidence of disturbed BRS in comparison with weight-matched non-OSA controls.

Peroxisomal D-bifunctional protein deficiency: First case reports from Slovakia

D-bifunctional protein deficiency (#OMIM 261515) is a rare autosomal recessive hereditary metabolic disorder causing severe clinical and biochemical abnormalities that are usually fatal in the course of the first years of life. This disease is classified as single enzyme peroxisomal disorder affecting the β-oxidation pathway in this compartment. In this paper we present a full overview of the clinical presentation, magnetic resonance imaging, biochemical and molecular data of two Slovak D-bifunctional protein deficient patients. In the clinical presentation of both patients severe generalized hypotonia, depression of neonatal reflexes, craniofacial dysmorphism and seizures dominated starting from the second day of life. In both patients, who died up to two years of life, we found elevated plasma levels of very long chain fatty acids and we identified the presence of causative mutations in the HSD17B4 gene. In the first case, we found the homozygous mutation c.46G>A, which is responsible for a defect in the dehydrogenase domain. In the second patient, the heterozygous mutations c.1369A>G and c.1516C>T were present and functionally they are related to the hydratase domain of the protein. This combination of mutations in the second patient is very rare and has not been reported until now. The presence of mutations was examined in all family members, and the resulting data were successfully utilized for prenatal diagnosis.

Calculating degree of neural impingement in radiculopathy using H-reflexes in loading and unloading: evidence on how to treat

Background: Neural compression of nerve roots in radiculopathymay bemeasured by imaging techniques. Such anatomical method may not parallel the pathophysiologic changes in those patients. There is a need to develop an electrophysiological method to measure the degree of neural impingement in radiculopathy in order to guide the treatment protocol. Purpose: The purpose of this study is to evaluate a new method of testing using the soleus H-reflex in loading and unloading in patients with lumbosacral radiculopathy (LR). The H-reflex is considered to be the most appropriate electrophysiologic procedure for testing nerve root function. Methods: Patients (n= 58) with LR (32 female and 26 males) with age range of 21–91 years were tested during our clinical services in the last 4 years. The patients’ diagnosis was confirmedby clinical, imaging andEMGtesting. Patients were classified as acute (less than 6 wks), subacute (6 wks. to 6 mo.) and chronic (>6mo.). Patients were tested using the soleus H-reflex in the right and left lower limbs during prone-lying (unloading) and standing (loading). The Tibial nerve was electrically stimulated at the popliteal fossa (1ms, 0.2 pps at H-max) while recording Soleus H-reflex using surface electrodes. Dependent parameters include peak-to-peak amplitude and deflection latency of the H-reflex. Five H-traces were averaged for each of the 4 trials (right and left lying; and right and left standing). The ratio of the mean amplitude of the more symptomatic (associated usually with the smaller H-reflex) was divided by the less symptomatic (or non-symptomatic) limb during lying and then during standing was calculated. This ratio indicates the degree of neural impingement caused by posture. The percentageofH-right (stand)/(lying)was also calculated. Similar ratio calculationwas carried out for the left lower limb to evaluate the effect of mechanical shift at the spine during loading versus unloading, in each lower limb. The data was then presented in 4-cells table, and the vertical (column) and horizontal (row) comparison was analyzed to assess the degree of mechanically driven neural impingement of the patient. The datawas comparedwith the patient’s radicular symptoms and imaging reports. Results: The results showed that the degree of reflex depression usually increased during standing versus lying position that was more pronounced in the symptomatic than in the non-symptomatic (or less symptomatic) limb. The degree of reflex depression increased with the spread of symptoms to the distal limb segments and/or the chronicity of the symptoms; all are indicating increased degree of neural impingement with the mechanical or time factors of the pathology. Conclusion(s): The proposed method for calculating neural impingement that is sensitive to mechanical and timerelated (chronicity) factors can be used in designing a more effective treatment protocol using the unloading versus loading mechanical effect. Implications: Numerical evaluation of the neural impingement of the nerve root in radiculopathy provides the evidence-based assessment that is needed for directionsensitive exercise and rehabilitation therapy. This proposed method can be used in selecting the treatment posture mentioned in our previous publications on radiculopathy.

Characteristics of preceding Ia activity on postactivation depression in health and disease.

Previous activation of the soleus Ia afferents causes a depression in the amplitude of the H-reflex. This mechanism is referred to as postactivation depression (PAD) and is suggested to be presynaptically mediated. With the use of a paired reflex depression paradigm (eliciting two H-reflexes with conditioning-test intervals from 80 ms to 300 ms), PAD was examined in a group of healthy individuals and a group of hemiplegic patients. Healthy individuals showed substantial depression of the test H-reflex at all intervals. Although the patient group showed substantially less depression at all intervals, increasing the interval between the two reflexes sharply reduced the depression. In a separate experiment, we varied the size of the conditioning H-reflex against a constant test H-reflex. In healthy individuals, by increasing the size of the conditioning H-reflex, the amplitude of the test H-reflex exponentially decreased. In the patient group, however, this pattern was dependent on the conditioning-test interval; increasing the size of the conditioning H-reflex caused an exponential decrease in the size of the test reflex at intervals shorter than 150 ms. This pattern was similar to that of healthy individuals. However, conducting the same protocol at a longer interval (300 ms) in these patients resulted in an abnormal pattern (instead of an exponential decrease in the size of the test reflex, exaggerated responses were observed). Fisher discriminant analysis suggested that these two patterns (which differed only in the timing between the two stimuli) were substantially different from each other. Therefore, it is suggested that the abnormal pattern of PAD in hemiplegic stroke patients could be a contributing factor for the pathophysiology of spasticity.

Chronic intermittent hypoxia orchestrates cardiorespiratory cacophony--adapting melody to malady.

Chronic intermittent hypoxia orchestrates cardiorespiratory cacophony--adapting melody to malady.

Bisphenol A depresses monosynaptic and polysynaptic reflexes in neonatal rat spinal cord in vitro involving estrogen receptor-dependent NO-mediated mechanisms

Bisphenol A (BPA), a toxic chemical from plastics, is known to produce locomotor abnormalities which may imply the alteration in synaptic activity at Ia-α motoneuron synapse also. However the effect of BPA on this synapse is not known. Therefore, this study was undertaken to examine the effect of BPA on reflexes originating at Ia-α motoneuron synapse in the spinal cord. The experiments were performed on isolated hemisected spinal cords from 4 to 6d rats. Stimulation of a dorsal root evoked segmental monosynaptic (MSR) and polysynaptic (PSR) reflex potentials in the corresponding ventral root. Nitrite content (indicator of NO activity) of cords was estimated in the presence of BPA with/without antagonists. Superfusion of BPA (3–100μM) depressed the reflexes in a concentration- and time-dependent manner. The depression was ∼20, ∼50 and ∼70% at 10, 30 and 100μM of BPA, respectively. The 50% depression occurred around 15min at 30μM of BPA. Pretreatment with estrogen receptor (ERα) antagonist, tamoxifen, blocked the BPA-induced depression of reflexes, whereas, 17β-estradiol, ER agonist, did not depress the reflexes even up to 10μM. Further, pretreatment with Nω-Nitro-l-arginine methyl ester hydrochloride (l-NAME) or hemoglobin (Hb) blocked the BPA-induced depression of spinal reflexes. Nitric oxide (NO) donor sodium-nitroprusside depressed the MSR and PSR in a concentration-dependent manner. The nitrite concentration of the cords exposed to BPA was 733μM/gm of tissue (three times the saline group). Pretreatment with tamoxifen/l-NAME/Hb blocked the BPA-induced increase of nitrite levels. The present observations indicate that BPA depressed spinal synaptic transmission through ERα-dependent NO-mediated mechanisms. The altered synaptic activity may implicate for neurobehavioral locomotor abnormalities after exposure to BPA.

The accuracy of the patellar reflex for localization of the site of a single level thoracolumbar disc herniation in dogs

The patellar reflex was used in this study to determine the site of thoracolumbar spinal cord dysfunction (T3-L3 or L4-L6) as a result of disc herniation. The results of neurological examinations were compared with the findings of CT myelography. This study was conducted on 21 dogs, selected from a total of 26 dogs confirmed to have a single thoracolumbar lesion. Results revealed that the accuracy of the patellar reflex for lesion localization was 71.4%. The accuracy of the patellar reflex (normal or hyperreflexic) for lesion localization in the T3-L3 segment in 15 dogs was 100%, while the accuracy of the depressed patellar reflex for lesion localization in the L4-L6 segment in 6 dogs was 0%. The accuracy of the patellar reflex for detection of laterality of a thoracolumbar lesion was low (33.33%). The results suggest that the patellar reflex was not reliable for neurolocalization of thoracolumbar spinal cord lesions in dogs. This could be related to the fact that the depressed reflex did not always refer to a lesion in the L4-L6 spinal cord segment. Moreover, the patellar reflex was not reliable in detecting the laterality of thoracolumbar lesions.

First-time fathers’ making a difference during labour and birth

Bisphenol A (BPA), a toxic chemical from plastics, is known to produce locomotor abnormalities which may imply the alteration in synaptic activity at Ia-α motoneuron synapse also. However the effect of BPA on this synapse is not known. Therefore, this study was undertaken to examine the effect of BPA on reflexes originating at Ia-α motoneuron synapse in the spinal cord. The experiments were performed on isolated hemisected spinal cords from 4 to 6 d rats. Stimulation of a dorsal root evoked segmental monosynaptic (MSR) and polysynaptic (PSR) reflex potentials in the corresponding ventral root. Nitrite content (indicator of NO activity) of cords was estimated in the presence of BPA with/without antagonists. Superfusion of BPA (3–100 μM) depressed the reflexes in a concentration- and time-dependent manner. The depression was ∼20, ∼50 and ∼70% at 10, 30 and 100 μM of BPA, respectively. The 50% depression occurred around 15 min at 30 μM of BPA. Pretreatment with estrogen receptor (ERα) antagonist, tamoxifen, blocked the BPA-induced depression of reflexes, whereas, 17β-estradiol, ER agonist, did not depress the reflexes even up to 10 μM. Further, pretreatment with Nω-Nitro-l-arginine methyl ester hydrochloride (l-NAME) or hemoglobin (Hb) blocked the BPA-induced depression of spinal reflexes. Nitric oxide (NO) donor sodium-nitroprusside depressed the MSR and PSR in a concentration-dependent manner. The nitrite concentration of the cords exposed to BPA was 733 μM/gm of tissue (three times the saline group). Pretreatment with tamoxifen/l-NAME/Hb blocked the BPA-induced increase of nitrite levels. The present observations indicate that BPA depressed spinal synaptic transmission through ERα-dependent NO-mediated mechanisms. The altered synaptic activity may implicate for neurobehavioral locomotor abnormalities after exposure to BPA.

Effects of anaesthesia techniques and drugs on pulmonary function.

The primary task of the lungs is to maintain oxygenation of the blood and eliminate carbon dioxide through the network of capillaries alongside alveoli. This is maintained by utilising ventilatory reserve capacity and by changes in lung mechanics. Induction of anaesthesia impairs pulmonary functions by the loss of consciousness, depression of reflexes, changes in rib cage and haemodynamics. All drugs used during anaesthesia, including inhalational agents, affect pulmonary functions directly by acting on respiratory system or indirectly through their actions on other systems. Volatile anaesthetic agents have more pronounced effects on pulmonary functions compared to intravenous induction agents, leading to hypercarbia and hypoxia. The posture of the patient also leads to major changes in pulmonary functions. Anticholinergics and neuromuscular blocking agents have little effect. Analgesics and sedatives in combination with volatile anaesthetics and induction agents may exacerbate their effects. Since multiple agents are used during anaesthesia, ultimate effect may be different from when used in isolation. Literature search was done using MeSH key words ‘anesthesia’, ‘pulmonary function’, ‘respiratory system’ and ‘anesthesia drugs and lungs’ in combination in PubMed, Science Direct and Google Scholar filtered by review and research articles sorted by relevance.

Comparison of propofol versus propofol with low dose scoline to evaluate lma insertion

Background: LMA insertion requires sufficient depth of anesthesia and depression of airway reflexes. Propofol is the agent of choice for LMA insertion as it is very effective in suppressing cough and gag reflexes. On the other hand addition of low dose scoline improves correct position of the laryngeal mask. Our main aim of study was to compare the hemodynamic changes, time taken for LMA insertion and ease of LMA insertion using Propofol v/s propofol with low dose scoline in both groups. Method: The study was conducted in sixty ASA-1 and ASA-2 grade patients. All patients were investigated preoperatively for routine investigations. Written informed consent was taken. After applying monitors all patients were premedicated with Inj. Ondensetron (4 mg), Inj. Glycopyrrolate (0.2 mg), injection midazolam 0.03 mg/kg IV two minutes before three minutes of preoxygenation. Gr p received Inj propofol 2.5 mg/kg/iv and Gr (P+S) received Inj propofol 2.5 mg/kg/iv with Inj Scoline 0.2 mg/kg/iv. Overall Grading of Insertion score, Rescue Drug Usage Grade, LMA Insertion time were noted. Patients were observed for any complication postoperatively. Result: Jaw opening was comparable but statistically insignificant in both groups. No vigorous movements were noted in (P+S) group while 6.67% patients in P group had vigorous movements. This was statistically significant (p

Chapter 10 - Organophosphorus and carbamate insecticide poisoning

Both organophosphorus (OP) and carbamate insecticides inhibit acetylcholinesterase (AChE), which results in accumulation of acetylcholine (ACh) at autonomic and some central synapses and at autonomic postganglionic and neuromuscular junctions. As a consequence, ACh binds to, and stimulates, muscarinic and nicotinic receptors, thereby producing characteristic features. With OP insecticides (but not carbamates), "aging" may also occur by partial dealkylation of the serine group at the active site of AChE; recovery of AChE activity requires synthesis of new enzyme in the liver. Relapse after apparent resolution of cholinergic symptoms has been reported with OP insecticides and is termed the intermediate syndrome. This involves the onset of muscle paralysis affecting particularly upper-limb muscles, neck flexors, and cranial nerves some 24-96 hours after OP exposure and is often associated with the development of respiratory failure. OP-induced delayed neuropathy results from phosphorylation and subsequent aging of at least 70% of neuropathy target esterase. Cramping muscle pain in the lower limbs, distal numbness, and paresthesiae are followed by progressive weakness, depression of deep tendon reflexes in the lower limbs and, in severe cases, in the upper limbs. The therapeutic combination of oxime, atropine, and diazepam is well established experimentally in the treatment of OP pesticide poisoning. However, there has been controversy as to whether oximes improve morbidity and mortality in human poisoning. The explanation may be that the solvents in many formulations are primarily responsible for the high morbidity and mortality; oximes would not be expected to reduce toxicity in these circumstances. even if given in appropriate dose.

Comparison of Sevoflurane and Propofol for Laryngeal Mask Airway Insertion in Children

INTRODUCTION: The major responsibility of an anaesthesiologist is to provide adequate ventilation for the patient by providing unobstructed airway. An anaesthetic technique is safe only when diligent efforts are devoted to maintain an intact functional airway. To maintain airway in an anaesthetized or unconscious patient we have supraglottic devices like anatomical face mask, laryngeal mask airway, cuffed oropharyngeal airway and combitube. Laryngeal mask airway was invented by Dr. ARCHIE BRAIN, United Kingdom in 1981. The LMA is an ingenious supraglottic airway device that is designed to provide and maintain a seal around the laryngeal inlet for spontaneous ventilation and allow controlled ventilation at modest levels of positive pressure. In controlled ventilation peak inflation pressure should not exceed 25cm H2O. An outstanding feature of LMA is that it provides a rapid clear airway in vast majority of patients and it is both faster and easier to insert than a tracheal tube. LMA can be used for pediatric and adult patients undergoing daycare surgeries. Successful insertion of LMA requires sufficient depth of anaesthesia and depression of airway reflexes to avoid gagging, coughing and laryngeal spasm. Propofol is the induction agent most commonly used for insertion of LMA. Sevoflurane is a recently introduced volatile anaesthetic agent which allows rapid smooth inhalational induction with excellent recovery. This study was being conducted to compare Sevoflurane and Propofol for insertion of laryngeal mask airway in children. This study was carried out in Dept. of Anaesthesiology, Stanley medical college, Chennai. AIM OF THE STUDY: The aim of the study is to compare the conditions of Laryngeal Mask Airway insertion in children after induction of anaesthesia with either inhalation of sevoflurane or intravenous propofol. The time taken for induction, time taken for jaw relaxation, time to LMA insertion, hemodynamic parameters, complications during induction and LMA insertion are compared. MATERIALS AND METHODS: Sixty patients of ASA physical status 1&2 undergoing elective minor surgical procedures below umbilicus lasting less than 60 mins. were included in the study. Patients belonged to age group of 4 – 12 of both sexes. It was a prospective randomized controlled study. The study was approved by institutional ethical committee and parent provided written informed consent before induction. Inclusion Criteria: 1. ASA I and II physical status. 2. No predicted airway difficulty. 3. Elective minor surgical procedures below umbilicus lasting less than 60 min. Exclusion Criteria: 1. Patients at risk of aspiration – upper GI surgery, gastroesophageal disease, not fasted. 2. Patients who require high positive pressure ventilation – eg. Pulmonary fibrosis. 3. Known allergy to any anaesthetic. MATERIALS: 1. Classic Laryngeal mask airways of appropriate size, 2. Propofol 1%, 3. Sevoflurane, 4. Fentanyl and glycopyrrolate, 5. Appropriate size oral airways, 6. 2,5 and 10 ml syringes, 7. Lubricant jelly. Preparation of the Patient: Informed consent from the parent obtained. All patients were fasted as per NPO guidelines. Premedication: Syp. Triclofos 60 mg/kg po given 45 min before shifting the child to operating room. METHODS: 1. Basal heart rate, blood pressure and oxygen saturation were recorded. 2. Intravenous access established. 3. Inj. Glycopyrrolate 10μg/kg and Inj. Fentanyl citrate 2 μg/kg i.v. given on table. 4. Preoxygenation with 100% O2 done for 3 min. SUMMARY: We assessed the conditions for insertion of LMA in two groups of patient receiving either inhalational sevoflurane or intravenous propofol and the following observations were made. • There were no significant differences between the two groups in demographic data. • The time to induction is less with sevoflurane compared to propofol in this study, though statistically not significant. • The time to jaw relaxation and the time to LMA insertion is less with propofol, with statistical significance. • The insertion is more successful by 1st attempt in the propofol group. But this is not statistically significant. • There are few cases who had movements during induction in propofol group and few cases had transient apnea during induction in sevoflurane group. • There is no significant difference between both groups in the incidence of coughing, gagging and laryngospasm. • There is significant difference in pulse rate in both groups. The pulse rates in propofol group decreased from baseline but within acceptable limits. In Sevoflurane group pulse rate increased from baseline during induction and LMA insertion, within acceptable limits. • The decrease in mean arterial pressure is observed in both groups and is not statistically significant. CONCLUSION: In conclusion, Propofol and Sevoflurane are equally effective for LMA insertion in children. However, Propofol has a faster insertion time due to early onset of jaw relaxation compared to sevoflurane and high success rate in 1st attempt for LMA insertion whereas Sevoflurane has better hemodynamic stability and less side effects compared to propofol.