Syringe pumps for vasoactive infusions have the advantages of small size and weight, portability,... more Syringe pumps for vasoactive infusions have the advantages of small size and weight, portability, and low cost of the disposable components. However, limited syringe capacity necessitates the use of high drug concentrations, and the accidental delivery of even a small volume of infusate could seriously alter the patient's hemodynamics. To determine the circumstances under which drug delivery might be delayed, or inadvertent boluses could be delivered into the manifold, two brands of commercially available clinical syringe pumps were connected to a stopcock manifold via small-bore tubing and a series of tests were performed. When the syringe pumps were operated at 3 mL/h against a closed stopcock, the pumps' occlusion alarms did not sound for 18-22 min, and when the stopcock subsequently was opened, 0.6-0.9 mL of infusate was delivered as a bolus. Elevating the syringe pump by 120 cm resulted in the delivery of up to 0.5 mL of infusate with the pump turned off. When a syringe pump operating at 6 mL/h was turned off, typically an additional 0.05 mL was delivered during the ensuing 2-3 min. Depending upon the method used to flush the tubing prior to use, delays in drug delivery of 2-3 min occurred at an infusion rate of 3 mL/h. These observations emphasize the need for careful equipment setup and proper use of the manifold stopcocks to avoid unintended drug administration or delay in drug administration.
A 58-year-old woman who was not taking beta-adrenergic block medication had a lumbar epidural cat... more A 58-year-old woman who was not taking beta-adrenergic block medication had a lumbar epidural catheter placed intravascular unintentionally. Epinephrine 15 micrograms in 3 ml saline or 2% lidocaine caused an increase in blood pressure and a decrease in heart rate. Observation of the patient for other signs of intravascular injection besides an increase in heart rate is discussed.
The question of myocardial catecholamine oxygen wasting was reexamined in a two-part study. In th... more The question of myocardial catecholamine oxygen wasting was reexamined in a two-part study. In the first phase, the effects of independently varying systolic blood pressure, heart rate, and stroke volume were observed in closed-chest, anesthetized dogs. This was achieved by cardiac pacing, phenylephrine infusion, controlled hemorrhage, and adjustment of arteriovenous shunts. Pretreatment with propranolol was used to hold contractility constant. From these results, where myocardial oxygen consumption was varied by changing preload and afterload, a new pressure-work index was devised and fitting parameters for other indexes of myocardial oxygen consumption were determined.
Intravenous medication has been the most common method of induction of general anesthesia for man... more Intravenous medication has been the most common method of induction of general anesthesia for many decades, primarily due to the speed of onset, lack of patient discomfort as unconsciousness develops, and the ability to select a drug (or drugs) and dosages tailored to the patient’s medical status. As there is no single ideal induction agent, the relative advantages and disadvantages of each agent must be understood in order to make a rational choice, especially for the older patient whose organ systems demonstrate diminished reserve with greater sensitivity and more adverse effects than their younger counterparts.
According to a 2006 statistical update published by the American Heart Association, 37.3% of all ... more According to a 2006 statistical update published by the American Heart Association, 37.3% of all deaths in the United States in 2003 were attributable to cardiovascular disease (CVD).1 About 83% of the deaths related to CVD occur in people age 65 and older. The prevalence of CVD in American men and women aged 65–74 are 68.5% and 75%, respectively. For those aged 75+, prevalence is 77.8% and 86.4%, respectively. These numbers demonstrate the strong association between adverse cardiac events and the aging process.
When subjected to total body heating and exercise, skin blood flow does not increase as much in e... more When subjected to total body heating and exercise, skin blood flow does not increase as much in elderly as in young subjects. It is not known whether this age-related decline is due to the autonomic dysfunction that develops in the elderly or to changes at the level of the blood vessels of the skin. We used local heating of the forearm to quantify the intrinsic ability of the cutaneous vasculature to dilate in seven young men (avg age 31 yr) and seven elderly men (avg age 71 yr). A water spray was used to maintain a neutral skin temperature of 32-35 degrees C for > 10 min, followed by 60 min of a 42 degrees C skin temperature to induce maximal skin blood flow. Forearm blood flow was measured by venous occlusion plethysmography with a mercury-in-Silastic circumference gauge. At the neutral skin temperature, forearm blood flows in the elderly subjects were comparable to those in the young subjects: 3.0 +/- 0.5 vs. 2.8 +/- 1.0 ml.min-1 x 100 ml-1. During the last 10 min of heating, however, blood flows were much lower in the elderly than in the young subjects: 11.1 +/- 2.7 vs. 19.9 +/- 5.2 ml.min-1 x 100 ml-1 (P = 0.002). We conclude that aging results in a reduction of the maximal conductance of the cutaneous vasculature.
Canadian Journal Of Anesthesia/journal Canadien D'anesthésie, Jul 1, 1997
Reduction in postintubation respiratory resistance by isoflurane and albuterol Purpose: This stud... more Reduction in postintubation respiratory resistance by isoflurane and albuterol Purpose: This study examined the bronchodilating effects of 0.6 MAC and I. I MAC isoflurane (ISF) on respiratory system resistance (R) following tracheal intubation and determined whether albuterol supplements that effect. Methods: Sixty-seven adult patients were anaesthetized with 2 pg-kg ~ fentanyl and 5 mg'kg ' thiopentone and their tracheas intubated following administration of I mg-kg L succinylcholine. Respiratory system resistance was measured following intubation and the patients then randomized to receive either I. I MAC ISF in oxygen or 0.6 MAC ISF in 50% nitrous oxide and oxygen. Ten minutes later, R was again measured. Patients were then further randomized to receive albuterol or a placebo using incremental doses of 2, 5, and 10 puffs (albuterol puff = 90/ag) delivered via a metered dose inhaler at ten minute intervals. Results-tsoflurane at I. I MAC decreased post-intubation R by 23 • 5% (mean • sem) whereas the decrease was only 7 • 5% for 0.6 MAC ISF (P < 0.01). Two puffs of albuterol resulted in a further decrease of 12 _+ 3% (mean _+_ sem) in R compared with a 2 _ 4% decrease in the placebo groups (P < 0.05). Additional puffs of albuterol resulted in no further changes in R~. Conclusion; We conclude that following tracheal intubation the reduction in R produced by ISF is highly concentration dependent. Albuterol results in a small further reduction in R< Objectif : I~tudier I'effet bronchodilatateur de I'isoflurane (ISF) ,~ 0,6 MAC et ,~ I, I MAC sur la r~sistance du sys-t~me respiratoire (Rrs) apr~s I'intubation trach~ale et d~terminer si I'albut&ol amplifie cet effet. M&hodes : Soixante-sept adultes anesth~si& au fentanyl 2/~g-kg ~ et au thiopentone 5 mg.kg ' ont 6t~ intub6s apr& I'administration de succinylcholine I mg-kg-~. La r&istance du syst~me respiratoire a ~t~ mesur~e apr& I'intubation et les patients ont ~t~ r~partis al~atoirement pour recevoir soit ISF I, I MAC ou ISF 0,6 MAC dans le protoxyde d'azote 50% en oxyg~ne. Dix minutes plus tard, la Rrs a ~t~ mesur6e de nouveau. Les patients ont ~t6 de nouveau r~partis al~atoirement pour recevoir de I'albut&ol ou un placebo en dose fractionn~es de 2, 5 et I 0 bouff~es (une bouff~e d'albut&ol = 90 jug) d~livr~es par un inhalateur gradu~ ~ dix minutes d'intervalles. Rb.sultats : ILisoflurane ~ I, I MAC diminue la R.rs de 23 +_ 5% (moyenne-+ sem) alors que la diminution n'~tait que de 7 + 5% avec I'isoflurane a 0,6 MAC (P < 0,01). Deux bouff~es d'albut&ol ont provocluc a une nouvetle baisse de 12 _+ 3% (moyenne +_ sem) de la R.rs comparativement ,~ 2 _+ 4% dans le groupe placebo (P < 0,05). Les bouff~es additionnelles d'albut&ol n'ont pas modifi~ davantage la RTs. Conclusion : Apr~s une intubation trach~ale, la r~duction de la R.rs produite par I'isoflurane d6pend fortement de sa concentration. I'albut&ol provoque une petite r~duction additionnelle.
onic muscle rigidity is a well-known side effect of induction of anesthesia with opioids, includ-... more onic muscle rigidity is a well-known side effect of induction of anesthesia with opioids, includ-T ing morphine (l), fentanyl, and fentanyl analogs such as sufentanil and alfentanil (2). Clonic muscle activity (myoclonus) also occurs during induction with opioids and may resemble generalized seizures (3,4). However, myoclonus resulting from fentanyl analogs is not associated with electroencephalographic evidence of seizure activity (3,5,6). The mechanism of opioid-related myoclonus is probably similar to the mechanism of opioid-related tonic rigidity, involving opioid receptors in the brainstem and basal ganglia (7-9). Although rigidity and myoclonus related to opioid administration usually have been observed during induction of anesthesia, there are also a few case reports of tonic rigidity that developed postoperatively (10-14). Naloxone terminated the rigidity in all of the patients to whom it was given, suggesting that the mechanism of rigidity was related to opioid receptors. We report a case of severe myoclonus that occurred during emergence from anesthesia with sufentanil. We also review previous case reports of postoperative, opioid-related tonic rigidity and suggest possible etiologic mechanisms. Case Report A 36-yr-old, 60-kg woman was anesthetized for breast biopsy and diagnostic pelvic laparoscopy. There was no history of seizures or other neurologic abnormalities, except for occasional migraine headaches. Anesthesia was induced intravenously (IV) with sufentanil, 60 pg, and thiopental, 150 mg. When the patient was unconscious, succinylcholine, 100 mg, was given IV to facilitate tracheal intubation. Neither rigidity nor myoclonus was noted during induction of anesthesia. After endotracheal intubation, anesthesia was maintained with isoflurane, 0.5% end-tidal concentration, in 50% oxygen. No additional opioids were given after induction. Metocurine, 3 mg, and pancuronium, 0.75 mg, were given IV for
Degradation of sevoflurane by carbon dioxide absorbents during low-flow anesthesia forms the halo... more Degradation of sevoflurane by carbon dioxide absorbents during low-flow anesthesia forms the haloalkene compound A, which causes nephrotoxicity in rats. A number of studies have shown no ill effects of compound A formation on postoperative renal function after moderate-duration (3-4 hr) low-flow sevoflurane; however, effects of longer exposure continue to be unresolved. A comparison was made of renal function after long-duration low-flow (<1 L/min) sevoflurane and isoflurane anesthesia in consenting surgical patients who had normal renal function. To maximize degradant exposure, Baralyme was used, and anesthetic concentrations were maximized (no nitrous oxide and minimal opioids). Inspired and expired compound A concentrations were quantified. Blood and urine were taken for laboratory evaluation. Sevoflurane (n = 28) and isoflurane (n = 27) groups were similar with regard to age, sex, weight, ASA status, and anesthetic duration (9.1 ± 3.0 and 8.2 ± 3.0 hr, mean ± SD) and exposure (9.2 ± 3.6 and 9.1 ± 3.7 minimum alveolar anesthetic concentration hours). Maximum inspired compound A was 25 ± 9 ppm (range, 6-49 ppm) and exposure (area under the concentration-time curve) was 165 ± 95 (35-428) ppm/hr. No marked difference existed between anesthetic groups in 24-or 72hr serum creatinine, blood urea nitrogen, creatinine clearance, or 0-to 24-hr or 48-to 72-hr urinary protein or glucose excretion. Proteinuria and glucosuria were common in both groups. No correlation existed between compound A exposure and any measure of renal function. There was no difference between anes
Syringe pumps for vasoactive infusions have the advantages of small size and weight, portability,... more Syringe pumps for vasoactive infusions have the advantages of small size and weight, portability, and low cost of the disposable components. However, limited syringe capacity necessitates the use of high drug concentrations, and the accidental delivery of even a small volume of infusate could seriously alter the patient&#39;s hemodynamics. To determine the circumstances under which drug delivery might be delayed, or inadvertent boluses could be delivered into the manifold, two brands of commercially available clinical syringe pumps were connected to a stopcock manifold via small-bore tubing and a series of tests were performed. When the syringe pumps were operated at 3 mL/h against a closed stopcock, the pumps&#39; occlusion alarms did not sound for 18-22 min, and when the stopcock subsequently was opened, 0.6-0.9 mL of infusate was delivered as a bolus. Elevating the syringe pump by 120 cm resulted in the delivery of up to 0.5 mL of infusate with the pump turned off. When a syringe pump operating at 6 mL/h was turned off, typically an additional 0.05 mL was delivered during the ensuing 2-3 min. Depending upon the method used to flush the tubing prior to use, delays in drug delivery of 2-3 min occurred at an infusion rate of 3 mL/h. These observations emphasize the need for careful equipment setup and proper use of the manifold stopcocks to avoid unintended drug administration or delay in drug administration.
A 58-year-old woman who was not taking beta-adrenergic block medication had a lumbar epidural cat... more A 58-year-old woman who was not taking beta-adrenergic block medication had a lumbar epidural catheter placed intravascular unintentionally. Epinephrine 15 micrograms in 3 ml saline or 2% lidocaine caused an increase in blood pressure and a decrease in heart rate. Observation of the patient for other signs of intravascular injection besides an increase in heart rate is discussed.
The question of myocardial catecholamine oxygen wasting was reexamined in a two-part study. In th... more The question of myocardial catecholamine oxygen wasting was reexamined in a two-part study. In the first phase, the effects of independently varying systolic blood pressure, heart rate, and stroke volume were observed in closed-chest, anesthetized dogs. This was achieved by cardiac pacing, phenylephrine infusion, controlled hemorrhage, and adjustment of arteriovenous shunts. Pretreatment with propranolol was used to hold contractility constant. From these results, where myocardial oxygen consumption was varied by changing preload and afterload, a new pressure-work index was devised and fitting parameters for other indexes of myocardial oxygen consumption were determined.
Intravenous medication has been the most common method of induction of general anesthesia for man... more Intravenous medication has been the most common method of induction of general anesthesia for many decades, primarily due to the speed of onset, lack of patient discomfort as unconsciousness develops, and the ability to select a drug (or drugs) and dosages tailored to the patient’s medical status. As there is no single ideal induction agent, the relative advantages and disadvantages of each agent must be understood in order to make a rational choice, especially for the older patient whose organ systems demonstrate diminished reserve with greater sensitivity and more adverse effects than their younger counterparts.
According to a 2006 statistical update published by the American Heart Association, 37.3% of all ... more According to a 2006 statistical update published by the American Heart Association, 37.3% of all deaths in the United States in 2003 were attributable to cardiovascular disease (CVD).1 About 83% of the deaths related to CVD occur in people age 65 and older. The prevalence of CVD in American men and women aged 65–74 are 68.5% and 75%, respectively. For those aged 75+, prevalence is 77.8% and 86.4%, respectively. These numbers demonstrate the strong association between adverse cardiac events and the aging process.
When subjected to total body heating and exercise, skin blood flow does not increase as much in e... more When subjected to total body heating and exercise, skin blood flow does not increase as much in elderly as in young subjects. It is not known whether this age-related decline is due to the autonomic dysfunction that develops in the elderly or to changes at the level of the blood vessels of the skin. We used local heating of the forearm to quantify the intrinsic ability of the cutaneous vasculature to dilate in seven young men (avg age 31 yr) and seven elderly men (avg age 71 yr). A water spray was used to maintain a neutral skin temperature of 32-35 degrees C for &gt; 10 min, followed by 60 min of a 42 degrees C skin temperature to induce maximal skin blood flow. Forearm blood flow was measured by venous occlusion plethysmography with a mercury-in-Silastic circumference gauge. At the neutral skin temperature, forearm blood flows in the elderly subjects were comparable to those in the young subjects: 3.0 +/- 0.5 vs. 2.8 +/- 1.0 ml.min-1 x 100 ml-1. During the last 10 min of heating, however, blood flows were much lower in the elderly than in the young subjects: 11.1 +/- 2.7 vs. 19.9 +/- 5.2 ml.min-1 x 100 ml-1 (P = 0.002). We conclude that aging results in a reduction of the maximal conductance of the cutaneous vasculature.
Canadian Journal Of Anesthesia/journal Canadien D'anesthésie, Jul 1, 1997
Reduction in postintubation respiratory resistance by isoflurane and albuterol Purpose: This stud... more Reduction in postintubation respiratory resistance by isoflurane and albuterol Purpose: This study examined the bronchodilating effects of 0.6 MAC and I. I MAC isoflurane (ISF) on respiratory system resistance (R) following tracheal intubation and determined whether albuterol supplements that effect. Methods: Sixty-seven adult patients were anaesthetized with 2 pg-kg ~ fentanyl and 5 mg'kg ' thiopentone and their tracheas intubated following administration of I mg-kg L succinylcholine. Respiratory system resistance was measured following intubation and the patients then randomized to receive either I. I MAC ISF in oxygen or 0.6 MAC ISF in 50% nitrous oxide and oxygen. Ten minutes later, R was again measured. Patients were then further randomized to receive albuterol or a placebo using incremental doses of 2, 5, and 10 puffs (albuterol puff = 90/ag) delivered via a metered dose inhaler at ten minute intervals. Results-tsoflurane at I. I MAC decreased post-intubation R by 23 • 5% (mean • sem) whereas the decrease was only 7 • 5% for 0.6 MAC ISF (P < 0.01). Two puffs of albuterol resulted in a further decrease of 12 _+ 3% (mean _+_ sem) in R compared with a 2 _ 4% decrease in the placebo groups (P < 0.05). Additional puffs of albuterol resulted in no further changes in R~. Conclusion; We conclude that following tracheal intubation the reduction in R produced by ISF is highly concentration dependent. Albuterol results in a small further reduction in R< Objectif : I~tudier I'effet bronchodilatateur de I'isoflurane (ISF) ,~ 0,6 MAC et ,~ I, I MAC sur la r~sistance du sys-t~me respiratoire (Rrs) apr~s I'intubation trach~ale et d~terminer si I'albut&ol amplifie cet effet. M&hodes : Soixante-sept adultes anesth~si& au fentanyl 2/~g-kg ~ et au thiopentone 5 mg.kg ' ont 6t~ intub6s apr& I'administration de succinylcholine I mg-kg-~. La r&istance du syst~me respiratoire a ~t~ mesur~e apr& I'intubation et les patients ont ~t~ r~partis al~atoirement pour recevoir soit ISF I, I MAC ou ISF 0,6 MAC dans le protoxyde d'azote 50% en oxyg~ne. Dix minutes plus tard, la Rrs a ~t~ mesur6e de nouveau. Les patients ont ~t6 de nouveau r~partis al~atoirement pour recevoir de I'albut&ol ou un placebo en dose fractionn~es de 2, 5 et I 0 bouff~es (une bouff~e d'albut&ol = 90 jug) d~livr~es par un inhalateur gradu~ ~ dix minutes d'intervalles. Rb.sultats : ILisoflurane ~ I, I MAC diminue la R.rs de 23 +_ 5% (moyenne-+ sem) alors que la diminution n'~tait que de 7 + 5% avec I'isoflurane a 0,6 MAC (P < 0,01). Deux bouff~es d'albut&ol ont provocluc a une nouvetle baisse de 12 _+ 3% (moyenne +_ sem) de la R.rs comparativement ,~ 2 _+ 4% dans le groupe placebo (P < 0,05). Les bouff~es additionnelles d'albut&ol n'ont pas modifi~ davantage la RTs. Conclusion : Apr~s une intubation trach~ale, la r~duction de la R.rs produite par I'isoflurane d6pend fortement de sa concentration. I'albut&ol provoque une petite r~duction additionnelle.
onic muscle rigidity is a well-known side effect of induction of anesthesia with opioids, includ-... more onic muscle rigidity is a well-known side effect of induction of anesthesia with opioids, includ-T ing morphine (l), fentanyl, and fentanyl analogs such as sufentanil and alfentanil (2). Clonic muscle activity (myoclonus) also occurs during induction with opioids and may resemble generalized seizures (3,4). However, myoclonus resulting from fentanyl analogs is not associated with electroencephalographic evidence of seizure activity (3,5,6). The mechanism of opioid-related myoclonus is probably similar to the mechanism of opioid-related tonic rigidity, involving opioid receptors in the brainstem and basal ganglia (7-9). Although rigidity and myoclonus related to opioid administration usually have been observed during induction of anesthesia, there are also a few case reports of tonic rigidity that developed postoperatively (10-14). Naloxone terminated the rigidity in all of the patients to whom it was given, suggesting that the mechanism of rigidity was related to opioid receptors. We report a case of severe myoclonus that occurred during emergence from anesthesia with sufentanil. We also review previous case reports of postoperative, opioid-related tonic rigidity and suggest possible etiologic mechanisms. Case Report A 36-yr-old, 60-kg woman was anesthetized for breast biopsy and diagnostic pelvic laparoscopy. There was no history of seizures or other neurologic abnormalities, except for occasional migraine headaches. Anesthesia was induced intravenously (IV) with sufentanil, 60 pg, and thiopental, 150 mg. When the patient was unconscious, succinylcholine, 100 mg, was given IV to facilitate tracheal intubation. Neither rigidity nor myoclonus was noted during induction of anesthesia. After endotracheal intubation, anesthesia was maintained with isoflurane, 0.5% end-tidal concentration, in 50% oxygen. No additional opioids were given after induction. Metocurine, 3 mg, and pancuronium, 0.75 mg, were given IV for
Degradation of sevoflurane by carbon dioxide absorbents during low-flow anesthesia forms the halo... more Degradation of sevoflurane by carbon dioxide absorbents during low-flow anesthesia forms the haloalkene compound A, which causes nephrotoxicity in rats. A number of studies have shown no ill effects of compound A formation on postoperative renal function after moderate-duration (3-4 hr) low-flow sevoflurane; however, effects of longer exposure continue to be unresolved. A comparison was made of renal function after long-duration low-flow (<1 L/min) sevoflurane and isoflurane anesthesia in consenting surgical patients who had normal renal function. To maximize degradant exposure, Baralyme was used, and anesthetic concentrations were maximized (no nitrous oxide and minimal opioids). Inspired and expired compound A concentrations were quantified. Blood and urine were taken for laboratory evaluation. Sevoflurane (n = 28) and isoflurane (n = 27) groups were similar with regard to age, sex, weight, ASA status, and anesthetic duration (9.1 ± 3.0 and 8.2 ± 3.0 hr, mean ± SD) and exposure (9.2 ± 3.6 and 9.1 ± 3.7 minimum alveolar anesthetic concentration hours). Maximum inspired compound A was 25 ± 9 ppm (range, 6-49 ppm) and exposure (area under the concentration-time curve) was 165 ± 95 (35-428) ppm/hr. No marked difference existed between anesthetic groups in 24-or 72hr serum creatinine, blood urea nitrogen, creatinine clearance, or 0-to 24-hr or 48-to 72-hr urinary protein or glucose excretion. Proteinuria and glucosuria were common in both groups. No correlation existed between compound A exposure and any measure of renal function. There was no difference between anes
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