Biomedical subjects

L Aziz

Publications and source records attributed to L Aziz.

10 recordsLinked to original sources

PubMed1997

The effect of priming with vecuronium and rocuronium on young and elderly patients.

UNLABELLED: The priming principle consists of administering a subparalyzing dose of nondepolarizing neuromuscular blocking drug 3-6 min before giving a second dose for tracheal intubation. This study was performed to observe the effects of priming doses of vecuronium and rocuronium on pulmonary function tests and muscular weaknesses in young (25-35 yr of age) and elderly (65-73 yr of age) patients. Ten young and 10 elderly patients were each placed in vecuronium and rocuronium groups. Oxygen saturation and train-of-four (TOF) ratio were determined, and pulmonary function tests were performed. Then 20% of the 95% effective dose (ED95) of the muscle relaxants was given intravenously. All tests were performed again 4 min after vecuronium and 3 min after rocuronium. Other signs of muscular weaknesses were also recorded. Elderly patients showed more signs of muscle weakness in both groups. The TOF ratio was 0.77 and 0.79 in the elderly rocuronium and vecuronium groups, respectively, and 0.89 and 0.90 in the young rocuronium and vecuronium groups, respectively. Dynamic spirometry revealed decreases in forced expiratory volume in 1 s and forced vital capacity in both groups, and no significant changes in peak expiratory flow rate. The expiratory reserve volume was reduced more in the elderly groups. Oxygen saturation decreased in both groups. We conclude that oxygen saturation, pulmonary function, and muscle strength decrease more in the elderly than in their younger counterparts from priming doses of vecuronium or rocuronium. IMPLICATIONS: The priming principle consists of giving a subparalyzing dose of muscle relaxant 3-6 min before giving a second dose for tracheal intubation. We found that priming doses of vecuronium and rocuronium produced greater decreases in oxygen saturation and pulmonary function in the elderly (aged 65-73 yr) than their younger (aged 25-35 yr) counterparts. Priming may not be a safe approach in elderly patients.

Adult↗

PubMed1996

[Acid base changes and muscle relaxants].

Previous publications have provided conflicting results concerning the effects of respiratory and metabolic acid base changes on the neuromuscular effects of nondepolarizing muscle relaxants. The varying results can be attributed not only to experimental design or species difference, but also to the accompanying changes in the pharmacokinetics in vivo. Using the phrenic nerve-hemidiaphragm preparation of rats, in which many variables of in vivo studies can be eliminated, respiratory and metabolic acid-base changes were induced by varying carbon dioxide (PCO2) and bicarbonate (HCO3) concentrations in the Krebs' solution and their effects on the potencies of muscle relaxants were compared. Decreasing pH by increasing Pco2 or by decreasing HCO3 increased the potencies of the monoquaternary relaxants (d-tubocurarine, vecuronium and rocuronium), while pH changes did not affect the potencies of the bisquaternary relaxants (metocurine, pancuronium and pipecuronium). Above difference between mono- and bisquaternary relaxants may reflect pH-induced changes in the ionization of the tertiary ammonium and resulting in changes in the sensitivity to the anionic nicotinic receptors. Neostigmine-induced antagonism was not affected by acid-base changes. These results in vitro were compared and correlated with the previous results in vivo.

Acid-Base Equilibrium↗

PubMed1995

The effect of isoflurane and temperature on the actions of muscle relaxants in rat in vitro.

Hypothermia and isoflurane alone increase the potencies of steroidal muscle relaxants (MRs). We studied the combined influence of isoflurane and hypothermia on MR potency. Phrenic nerve-hemidiaphragm preparations of rats were mounted in modified Krebs' solution and aerated with 5% CO2-95% O2 gas mixture at 37 degrees C and 4% CO2 at 27 degrees C to maintain the CO2 content constant. Phrenic nerves were stimulated with 0.1 Hz supramaximal impulses and elicited tension of the diaphragm was recorded. Isoflurane 1% was added after stabilization of twitch tension and MR was added 60 min later. Twitch tension was reduced by 20% +/- 2.5% at 37 degrees C and 3.5% +/- 0.7% at 27 degrees C from control with only isoflurane. The IC50 (inhibitory concentration, 50%) values of the MRs decreased significantly (P < 0.05) with isoflurane at both temperatures. The ratios of the IC50 values without and with isoflurane of the benzylisoquinolinium MRs were significantly more at both temperatures (P < 0.05) indicating the enhancement of potentiation of their action by isoflurane over steroidal MRs. When the soluble concentration of isoflurane at 27 degrees C was kept similar to that of at 37 degrees C, the ratios of all the MRs were reduced significantly from the ratios at 37 degrees C, indicating a reduction of potentiation. When the partial pressure of isoflurane was kept constant at 37 degrees C and 27 degrees C, the potentiating action of the MRs by isoflurane was similar. But when the partial pressure was decreased to keep the concentration of isoflurane constant, the potentiation was reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Effect of hypothermia on the in vitro potencies of neuromuscular blocking agents and on their antagonism by neostigmine.

The effect of temperature on the potencies of neuromuscular blocking agents remains unclear. This study was undertaken to examine the effects of different neuromuscular blocking agents at 37 and 27 degrees C at a constant carbon dioxide content (alpha stat principle). The effect of neostigmine 1 mumol litre-1 induced antagonism of these agents was also investigated. Phrenic nerve-hemidiaphragm preparations of rats were mounted in modified Krebs solution, maintained at 37 degrees C and aerated with a 5% carbon dioxide-95% oxygen gas mixture, and at 27 degrees C with 4% carbon dioxide to maintain the carbon dioxide content of the solution constant. Phrenic nerves were stimulated with 0.1-Hz supra-maximal impulses of 0.2-ms duration and the elicited tension of the diaphragm recorded. The potencies of the steroidal neuromuscular blocking agents (rocuronium, vecuronium, pancuronium and pipecuronium) increased significantly at 27 degrees C (P < 0.05), while the potencies of the benzylisoquinolinium agents (tubocurarine and dimethyltubocurarine) did not change. Neostigmine-induced antagonism of the steroidal agents did not differ significantly between each other but differed significantly from the benzylisoquinolinium agents (P < 0.05) at both temperatures. The ratios of IC50 (inhibitory concentration, 50%) with and without neostigmine at hypothermia were slightly higher for the steroidal agents, indicating slight enhancement of antagonism by neostigmine at 27 degrees C. In contrast, the ratios were significantly greater at 27 degrees C (P < 0.05) for isoquinolinium agents, implying significant enhancement of antagonism. Our results indicate that at 27 degrees C the potency of all steroidal agents increased and neostigmine-induced antagonism was slightly enhanced.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

The effect of CO2-induced acid-base changes on the potencies of muscle relaxants and antagonism of neuromuscular block by neostigmine in rat in vitro.

We investigated the influence of CO2-induced acid-base changes on the potencies of the monoquaternary relaxants (rocuronium, vecuronium, and d-tubocurarine) and bisquaternary relaxants (pancuronium, pipecuronium, and metocurine), and on the antagonism of their neuromuscular block by neostigmine. Phrenic nerve-hemidiaphragm preparations of rats were used. The pH changes were induced by changing the CO2 concentration aerating the modified Krebs solution. The potencies of the monoquaternary relaxants increased at 9% CO2 (pH 7.2) and decreased at 2.5% CO2 (pH 7.6) from those of 5% CO2 (pH 7.4) both with and without neostigmine (P < 0.05), whereas the potencies of the bisquaternary drugs did not change significantly at different pH levels from control (pH 7.4) both with and without neostigmine. The slopes of the log concentration-percent response curves of each drug were not significantly different at each pH level. The ratios of inhibitory concentrations, 50% (IC50) values with and without neostigmine at each pH value for each drug were not significantly different indicating that the neostigmine-induced antagonism for each drug was not affected by the CO2-induced acid-base changes. But the ratios of the IC50 values of the steroidal relaxants (rocuronium, vecuronium, pancuronium, and pipecuronium) were significantly lower (P < 0.05) than those of the isoquinolinium drugs (d-tubocurarine and metocurine) at each pH level, suggesting that the antagonism is enhanced at each pH level for the isoquinolinium relaxants. The difference was independent of their monoquaternary or bisquaternary nature. These results suggest that CO2 increases the potency of the monoquaternary relaxants but does not affect the bisquaternary relaxants.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗

PubMed1993

Ketamine infusion for postoperative analgesia in asthmatics: a comparison with intermittent meperidine.

Narcotics commonly used for postoperative analgesia may release histamine and cause bronchospasm in asthmatics. Ketamine, on the other hand, provides analgesia and has the additional advantage of preventing and relieving bronchospasm. We therefore delivered subanesthetic doses of ketamine in combination with midazolam (5.88-6.42 micrograms.kg-1.min-1 and 1.17-1.28 micrograms.kg-1.min-1, respectively), via an infusion for postoperative analgesia after elective abdominal hysterectomy in patients with asthma. Data were compared with those from a similar group of patients receiving conventional intramuscular meperidine. A significant degree and earlier onset of analgesia (P < 0.05) was achieved in the ketamine group. For other variables no significant difference was observed between the groups (P > 0.05). Ketamine-midazolam infusion can thus provide a safe alternative to the usual parenteral narcotic therapy in asthmatics, in terms of analgesia and patient acceptability.

Adult↗

PubMed1993

Ketamine infusion for postoperative analgesia: a prospective cohort study in asthmatics.

Ketamine, most often used as an anaesthetic agent can provide adequate post operative analgesia when delivered in the form of infusion, replacing narcotics, which can cause bronchospasm in susceptible individuals. This cohort study was undertaken to assess the feasibility of providing complete post operative analgesia in asthmatics with ketamine delivered in sub-anaesthetic doses (6.10-6.41 ugm./kg.-1/min-1). Diazepam (0.97-1.02 ugm./kg.-1/min-1) was delivered from the same infusion to eliminate the unwanted effects of ketamine. Ketamine induced little alteration in blood pressure while tachycardia was significant (P < 0.05). Respiratory functions observed, were favourable for asthmatics. Diazepam helped in reducing ketamine induced side effects, but after infusion over long periods tendency of cumulation was observed. Complications encountered were minimum with more than 93% patient acceptability for this method of analgesia.

Adult↗

PubMed1992

Splenic salvage using an absorbable mesh: feasibility, reliability and safety.

Forty-nine adults underwent surgery for splenic injury: 17 (group 1) had salvage with a splenic mesh, seven (group 2) underwent other preservation techniques, and 25 (group 3) underwent splenectomy. There were six, zero and 11 hilar lesions in groups 1, 2 and 3, respectively. Seven of 15 associated lesions involved the digestive tract. There was no significant difference in transfusion requirements, length of operation or postoperative complications. One patient died in each of groups 1 and 2, and eight in group 3. Secondary splenectomy was performed once in groups 1 and 2. The duration of hospital stay was shorter in the preservation groups (1 and 2) than in group 3. Splenic preservation was feasible in 24 of 49 adults with splenic injury requiring surgery. The splenic mesh wrap is safe and reliable, and allows splenic salvage even with hilar injury.

Adolescent↗

PubMed1988

A comparison of the vasopressin response of rats to intraperitoneal and intravenous administration of hypertonic saline, and the effect of opioid and aminergic antagonists.

The vasopressin response of rats to i.p. injection of hypertonic sodium chloride (1.5 mol/l) was compared with that following i.v. infusion of 1.05 mol sodium chloride/l. The two regimes produced a similar vasopressin response in terms of the osmotic threshold, although the slopes of the plot of plasma vasopressin levels against plasma osmolality were not identical. Pretreatment with naloxone and levallorphan increased the resting vasopressin levels and effectively potentiated vasopressin release in response to hypertonic saline by reducing the osmotic threshold for hormone release. Thus, opioid peptides appear to exert an inhibitory effect on vasopressin release under resting and stimulated conditions. The adrenoreceptor antagonists propranolol, phenyoxybenzamine and phentolamine produced a fall in resting vasopressin concentrations while propranolol and phenoxybenzamine potentiated the osmotic release of vasopressin in association with a fall in the osmotic threshold. This would suggest that noradrenergic pathways are excitatory at rest while having an inhibitory effect on the osmotic response. Metoclopramide also produced a fall in resting plasma vasopressin concentrations while increasing the osmotic response. In contrast haloperidol did not affect the vasopressin response.

Animals↗

PubMedDate not supplied

The detection of Plasmodium falciparum and P. vivax in DNA-extracted blood samples using polymerase chain reaction.

Seventeen pairs of published primer sets were compared for their relative sensitivity to detect malaria DNA extracted from blood samples, which were obtained from Pakistani patients suffering from malaria. The primer sets investigated consisted of: (i) 9 pairs of direct primers and 3 sets of nested primers for detecting Plasmodium falciparum, (ii) 2 pairs of direct primers and 2 sets of nested primers for detecting P. vivax, and (iii) 1 set of multiplex primers for detecting both P. falciparum and P. vivax, simultaneously. After a miniscreen of 9 DNA-extracted blood samples using the 17 primer sets stated above, 5 primer sets were short-listed (based on their superior sensitivity) and used for a maxi-screen of DNA extracted from 126 microscopy-positive blood samples from Pakistan, with the following results. (i) For the detection of P. falciparum, the direct primer pair 'PF1 + PF2' gave a sensitivity of 95% and the nested primer set 'RIT405 + RIT406/RIT371 + RIT372' gave a sensitivity of 97%. (ii) For the detection of P. vivax, the direct primer pair 'Forward + Reverse' and the nested primer set 'PLF + UNR/PLF + VIR' both gave a sensitivity of 94%. (iii) The nested multiplex primer set 'rPLU5 + rPLU6/rFAL1 + rFAL2 + rVIV1 + rVIV2' gave a sensitivity of 97% and 96% for P. falciparum and P. vivax, respectively. It was concluded that the nested multiplex primer set was the most optimal primer set to use for the detection of malaria DNA extracted from blood samples. Furthermore, the nested multiplex primer set has the advantage of simultaneously detecting and differentiating between P. vivax and P. falciparum.

Animals↗