Respiration reflexes

Codeine (morphine methyl ether) resembles morphine in its general effect, but is less toxic and its depressant action less marked and less prolonged, whilst its stimulating action involves not only the spinal cord, but also the lower parts of the brain. In small doses in man it induces sleep, which is not so deep as that caused by morphine, and in large doses it causes restlessness and increased reflex excitability rather than sleep. The respiration is slowed less than by morphine (cf. table, p. 261). Cases of addiction for codeine can occur but according to Wolff they are rare. The best known ethers of morphine are ethylmorphine and benzyl-morphine [cf., table, p. 261), both used to replace morphine or codeine for special purposes. 

Delourme-Houdd finds that tabernanthine injected into dogs is hypotensive, decreases the rate and amplitude of respiration, reduces the reflex hypertension induced by occlusion of the carotids and, like... 

The nurse must report symptoms of succinimide overdosage immediately. Symptoms of overdosage in dude confuson, sleepiness, unsteadiness flaccid muscles slow shallow respirations nausea, vomiting, hypotension, absent reflexes nd CNS depression leading to coma. It is important to report symptoms to the primary health care provider immediately. Therapeutic serum blood levels of ethosuximide (Zarontin) range from 40 to 100 mcg/mL... 

Lethargy, drowsiness, impaired respiration, flushing, sweating, hypotension, weak to absent deep tendon reflexes... 

Death from overdose of barbiturates may occur and is more likely when more than 10 times the hypnotic dose is ingested. The barbiturates with high lipid solubility and short half-lives are the most toxic. Thus the lethal dose of phenobarbital is 6—10 g, whereas that of secobarbital, pentobarbital, or amo-barbital is 2-3 g. Symptoms of barbiturate poisoning include CNS depression, coma, depressed reflex activity, a positive Babinski reflex, contracted pupils (with hypoxia there may be paralytic dilation), altered respiration, hypothermia, depressed cardiac function, hypotension, shock, pulmonary complications, and renal failure. 

Cardiovascular (tachycardia, palpitations), sweating, respiration, GIT, muscle tension, tremor, muscle aches or soreness, nausea, exaggerated startle reflex, increased urinary frequency Hypervigilance, nail-biting, scratching... 

Acute physiological responses to opiate administration occur rapidly and include constricted pupils, decreased pulse rate, reduced body temperature, slowed respiration rate and impaired reflexes. In addition, there is a marked slowing of the digestive system through an altering of the tonus and motility of the stomach and intestines, allowing for greater water absorption. This last effect is not subject to tolerance, and constipation is a common side effect even for chronic users. Indeed, some report that this is the worst side effect of opiate use. 

Physical symptoms include dizziness, dysarthria, ataxia, nystagmus, lid ptosis, tachycardia, sweating, and increased deep tendon reflexes. Most subjects show some degree of hypertension, associated with increased minute and tidal volumes of respiration, increased formation of urine, and increased muscle tone. The latter may lead to increased serum creatinine phosphokinase concentration. With very large doses, convulsions and respiratory arrest are the terminal events (11). The course of clinical symptoms and signs following various doses of PCP is shown in Table 2. 

Giddiness, tension, anxiety, jitteriness, restlessness, emotional lability, excessive dreaming, insomnia, nightmares, headaches, tremor, withdrawal and depression, bursts of slow waves of elevated voltage in EEC, especially on over-ventilation, drowsiness, difficult concentration, slowness on recall, confusion, slurred speech, ataxia, generalized weakness, coma, with absence of reflexes, Cheyne-Stokes respirations, convulsions, depression of respiratory and circulatory centers, with dyspnea, cyanosis, and fall in blood pressure. 

The cough-suppressant (antitussive) effect produced by inhibition of the cough reflex is independent of the effects on nociception or respiration (antitussives codeine, noscapine). 

In another report, the acute oral LD50 for irassociated with lethal doses included those of pulmonary hyperemia and central nervous system depression including ataxia, loss of righting reflex, and depressed respiration. 

With severe intoxication by all routes, an excess of acetylcholine at the neuromuscular junctions of skeletal muscle causes weakness aggravated by exertion, involuntary twitchings, fasciculations, and eventually paralysis. The most serious consequence is paralysis of the respiratory muscles. Effects on the central nervous system include giddiness, confusion, ataxia, slurred speech, Cheyne-Stokes respiration, convulsions, coma, and loss of reflexes. The blood pressure may fall to low levels, and cardiac irregularities, including complete heart block, may occur. ... 

Enflurane (Ethrane) depresses myocardial contractility and lowers systemic vascular resistance. In contrast to halothane, it does not block sympathetic reflexes, and therefore, its administration results in tachycardia. However, the increased heart rate is not sufficient to oppose enflurane s other cardiovascular actions, so cardiac output and blood pressure fall. In addition, enflurane sensitizes the myocardium to catecholamine-induced arrhythmias, although to a lesser extent than with halothane. Enflurane depresses respiration through mechanisms similar to halothane s and requires that the patient s ventilation be assisted. 

The acute effects of depressants can include euphoria, anxiety reduction, anticonvulsant activity, sedation, ataxia, motor incoordination, impaired judgment, anesthesia, coma, and respiratory depression resulting in death. The benzodiazepines are rarely involved in lethality, but all CNS depressants enhance the effects of other depressant drugs. The physiological effects of high-dose depressants include miosis, shallow respiration, and reduction in reflex responses. 

Respiration and blood pressure are generally well maintained because of reflex stimulation and high sympathetic tone. 

The drug increases the heart rate, cardiac output and blood pressure which is due to sympathetic stimulation. Respiration is not depressed, muscle tone increases and reflexes are not abolished during anaesthesia. Ketamine has been recommended for short operations, unpleasant therapeutic and diagnostic procedures in children, operation in shocked patients and in obstetrics. 

Halothane is non-irritant and can be inhaled at high concentrations to produce rapid, smooth induction of anaesthesia. It obtunds the protec five pharyngeal and laryngeal reflexes. At deeper planes, tracheal intubation may be performed. Halothane has a pronounced bronchodilating action and this may be an advantage in patients with chronic obstructive airways disease. Both tachypnoea and slowing of respiration may be observed at deeper planes of anaesthesia. 

In the study by Hazleton Labs (1964), 1/4 rabbits exposed dermally to 3160 mg/kg under an occlusive bandage for 24 hours displayed marked depression, labored respiration, sprawling, and depressed reflexes (see Table 2-3). The other three rabbits at this dosage and at <794 mg/kg did not display any signs of toxicity. 

The nervous system is conventionally divided into the central nervous system (CNS the brain and spinal cord) and the peripheral nervous system (PNS neuronal tissues outside the CNS). The motor (efferent) portion of the nervous system can be divided into two major subdivisions autonomic and somatic. The autonomic nervous system (ANS) is largely independent (autonomous) in that its activities are not under direct conscious control. It is concerned primarily with visceral functions such as cardiac output, blood flow to various organs, and digestion, which are necessary for life. The somatic subdivision is largely concerned with consciously controlled functions such as movement, respiration, and posture. Both systems have important afferent (sensory) inputs that provide information regarding the internal and external environments and modify motor output through reflex arcs of varying size and complexity. 

The medulla is the ultimate center for regulating vegetative functions such as respiration, swallowing, heart rate, and blood pressure. Related to respiration are the coughing and vomiting reflexes also associated with this part of the brain. The medulla is a type of crossroads where various neuron bundles go into and out of the brain. The reticular activating system or RAS, a part of the diffuse group of neurons known as the reticular formation. 

The effects of morphine, codeine, and heroin in the brain are dose-related. Small doses produce drowsiness, decreased anxiety and inhibition, reduced concentration, muscle relaxation, pain relief, depressed respiration, constricted pupils, nausea, and a decreased cough reflex, which is why codeine found its way into cough suppressants. At slightly higher doses, morphine and heroin can produce a state of intense elation or euphoria. 

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