Hypotension ketamine

People trying low dosages report feeling disconnected from normal, everyday realities. Blood pressure and pulse are often elevated hypotension and bradycardia have been observed. "Ketamine has a wide margin of safety, observes Parke-Davis brochure "several instances of unintentional administration of overdoses of Ketalar (up to ten times that usually required) have been followed by prolonged but complete recovery. ... 

Methods for evaluating postural hypotension were described in conscious dogs (Baum et al. 1981), conscious rabbits (Sponer et al. 1981), in rats (Lee et al. 1982) and in cynomolgus monkeys during ketamine anesthesia (Pals and Orley 1983). 

Ketamine has unique properties that make it useful for certain pediatric procedures and for anesthetizing patients who are at risk for hypotension (low blood pressure) or bronchospasm... 

The side-effects of reserpine include hypotension, bradycardia and increased gastrointestinal motility and diarrhea (Lloyd et al 1985), all resulting from decreased sympathetic tone and increased parasympathetic tone. The hypotensive effects of reserpine may take days to several weeks to occur but may persist for 1 to 6 weeks after the withdrawal of the dmg. Administration of induction agents, such as xylazine and ketamine, that produce hypotension may be fatal in horses treated with reserpine. 

In the horse, induction with thiopental usually results in a brief increase in heart rate and a decrease in cardiac output but no significant change in arterial blood pressure. Arterial blood pressure is typically lower after thiopental induction than in ketamine-based anesthetic techniques (Bennett et al 1998, Muir et al 2000). However, when horses are placed on inhalation anesthetics for maintenance of anesthesia, the hemodynamic effects of the induction agents is short lived and the hypotension and reduced cardiac output typical of inhalation anesthesia predominates (Bennett et al 1998, Wagner et al 1996). Respiratory depression is significant with an accompanying increase in Paco2 and decrease in pH. 

Chronic renal disease may also affect metabolism, not necessarily because of impaired metabolism in the kidney, but because of an indirect effect of renal failure on liver metabolism. For example, in animals with renal failure it was observed that there was a decrease in hepatic cytochromes P-450 content, and consequently zoxazolamine paralysis time and ketamine narcosis time were prolonged. Cardiac failure may also affect metabolism by altering hepatic blood flow. However even after heart attack without hypotension or cardiac failure, metabolism may be affected. For example, the plasma clearance of lidocaine is reduced in this situation. Other diseases such as those which affect hormone levels hyper- or hypo-thyroidism, lack of or excess growth hormone, and diabetes can alter the metabolism of foreign compounds. 

Ketamine (Ketalar, others) has unique properties that make it useful for anesthetizing patients at risk for hypotension and bronchospasm and for certain pediatric procednres. However, significant side effects limit its rontine nse. Ketamine rapidly produces a hypnotic state qnite distinct from that of other anesthetics. Patients have profonnd analgesia, nnresponsiveness to commands, and amnesia bnt may have their eyes open, move their limbs involnntarily, and breathe spontaneously. This cataleptic state has been termed dissociative anesthesia. 

Thiopental and propofol are the two most commonly used parenteral agents. Thiopental has a long-established track record of safety. Propofol is advantageous for procedures where rapid return to a preoperative mental status is desirable. Etomidate usually is reserved for patients at risk for hypotension and/or myocardial ischemia. Ketamine is best suited for patients with asthma or for children undergoing short, painful procedures. 

If ketamine is used as the sole anesthetic in the attempted reduction of a dislocated shoulder joint, its actions will include (A) Analgesia Bradycardia Hypotension Muscle rigidity Respiratory depression... 

A) Emesis is more likely to occur with propofol than with other agents Hypotension is the major limitation to the use of ketamine... 

Ketamine (Ketalar) Dissociative (disconnected from surroundings) anesthesia, analgesia. Less hypotension than others. T heart rate, blood pressure, myocardial O2 consumption, and cerebral blood flow. Low risk of apnea following induction. Bronchodilation (useful in asthmatic patients). 

At anesthetic or analgesic doses, ketamine has a wide margin of safety and has little impact upon cardiovascular and respiratory function even in physiologically compromised populations. Preservation, even stimulation, of blood pressure and pulse rate are seen with high doses of ketamine such changes are minimal when very low doses are given. This pattern contrasts with the hypotension and/or bradycardia often seen... 

A 26-year-old man, a known ketamine user, collapsed. He had previously had severe urinary tract dysfunction treated with antibiotics [5Z J. A CT scan of the abdomen showed bilateral hydronephrosis and cystoscopy showed a significantly reduced bladder capacity without ureteric obstruction. He was hypotensive, acidotic, and in acute renal failure and... 

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