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Biomedical subjects

A N Sibai

Publications and source records attributed to A N Sibai.

At least 19 recordsLinked to original sources

Anterior ischaemic optic neuropathy after coronary artery bypass graft: the role of anaemia in diabetics.

PURPOSE: To ascertain factors associated with anterior ischaemic optic neuropathy (AION) following coronary artery bypass graft (CABG) in a Lebanese population. METHODS: A retrospective chart review of consecutive CABG performed over a 5-year period (1995-1999) in one medical centre. A comparison of clinical characteristics was carried out between AION cases and subjects free from AION. The variables analysed included history of diabetes as well as preoperative, intraoperative, or postoperative values of haematocrit, blood sugar, oxygen saturation, and arterial blood pressure. RESULTS: A total of 1,594 persons were included. Three subjects experienced acute visual loss from AION following CABG, all had diabetes mellitus, and two suffered from severe postoperative anaemia. Among diabetics (n=484), the risk of AION was significantly higher in subjects with postoperative haematocrit falling below 22 (28.6%) than the rest (0.21%) (P=0.001). Blood transfusion was given in two subjects with prompt visual recovery. CONCLUSIONS: Severe anaemia in patients undergoing CABG appears to be a risk factor for AION, especially in diabetics, and needs prompt correction to prevent or reverse the ischaemic ocular events.

Aged↗

Nitroglycerin relieves laryngospasm.

Two young healthy non-asthmatic non-smoking patients developed partial laryngospasm directly post-anaesthesia extubation after routine varicocelectomy and perianal abscess drainage operations under general anaesthesia. Nitroglycerin was administered intravenously in a dose of 4 microg/kg for both cases. The laryngospasm was completely relieved within a minute of nitroglycerin administration in both cases and the relief was maintained thereafter. The two cases suggest that nitroglycerin can be effective in the treatment of post-extubation partial laryngospasm in ASA (class I) patients.

Adult↗

Modification of an anesthesia machine for MRI suite.

The modification of a wall mounted anesthesia machine, rendering it nonmagnetic for use in the magnetic resonance imaging suite, is described. The modified anesthesia machine functioned properly at 1.8 m distance from 1.5 tesla electromagnet without degrading its imaging.

Anesthesiology↗

Double T-piece, an injector, and Bird ventilator use in MRI suite.

The double T-piece breathing system is described. The Bird Ventilator Mark 2 is utilised as an oxygen pressure jet to drive an injector placed at the distal end of the double T-piece breathing system. An active anti-pollution assembly is employed. Both the double T-piece breathing system and the anti-pollution assembly are valveless. The injector's design is described. The ventilator functioned properly at 1.8 m distance from 1.5 tesla electromagnet without degrading its imaging. The Bird ventilator, the injector, and the double T-piece breathing system are small in size, easy to handle, and can be used for paediatric and adult patients.

Adult↗

Hazards of nitrous oxide administration in presence of venous air embolism.

Nitrous oxide administration in presence of venous air embolism results in its volume augmentation. The present case report of a 50-year old patient undergoing posterior fossa tumor excision in the sitting position demonstrates the hazards of nitrous oxide in presence of venous air embolism. Administration of 66% nitrous oxide 140 minutes after the incidence of air embolism resulted in a significant decrease of end-tidal carbon dioxide tension, moderate hypotension, and tachycardia, suggesting volume augmentation of the air embolism. The results of our case report are in contrast to that by Shapiro et al who noted that nitrogen washout following administration of 100% oxygen was complete 65 minutes after the occurrence of venous air embolism. Shapiro and colleagues suggest the use of nitrous oxide challenge as a diagnostic aid in deciding when lung excretion of intravascular air is complete. However, our case report implies that nitrogen washout was not complete 140 minutes after venous air embolism incidence. Accordingly, we recommend to stop nitrous oxide administration once air embolism is suspected and to refrain from its re-administration throughout the rest of surgery.

Anesthetics, Inhalation↗

Comparison of flumazenil with aminophylline to antagonize midazolam in elderly patients.

We have compared, in a double-blind study, the efficacy of flumazenil with that of aminophylline in antagonizing the effects of midazolam in 60 patients (ASA I-II, mean age 66 yr) undergoing transurethral resection of prostate under spinal anaesthesia. All patients received midazolam 0.075 mg kg-1 i.v. and the test drugs were given 5 min after its administration. Patients were allocated randomly to receive i.v. flumazenil 0.01 mg kg-1, aminophylline 2 mg kg-1 or placebo saline 0.1 ml kg-1. One minute after administration, aminophylline caused 42% reversal of sedation, 66% of disorientation and 73% of lack of co-operation in comparison with placebo, although there was marked individual variation. Flumazenil caused complete and rapid antagonism of sedation, disorientation and lack of cooperation.

Aged↗

Epidural meperidine for control of autonomic hyperreflexia in a quadriplegic undergoing cystoscopy.

Epidural meperidine was used to control autonomic hyperreflexia (AH) during cystoscopy and transuretheral sphincterotomy, in a quadriplegic patient who had chronic spinal cord transection at C6 level. Meperidine 100 mg diluted in 10 ml saline was injected in the epidural space at L3-L4 level. Within 10 minutes and throughout the surgical procedure, the blood pressure stabilized at 125/70-140/80 mmHg. Epidural meperidine produces selective blockade of the spinal opiate receptors and hence may block the nociceptive reflexes below the level of cord transection and prevent AH.

Autonomic Nervous System Diseases↗

Recurarisation following a suxamethonium-alcuronium sequence in patients with atypical cholinesterase.

Alcuronium 10 mg was administered to maintain muscle relaxation in two patients before recovery from suxamethonium neuromuscular blockade to facilitate tracheal intubation. This sequence resulted in a markedly prolonged block which could not be antagonised adequately by neostigmine 0.05 mg/kg; initial antagonism was followed rapidly by prolonged recurarisation. Estimation of plasma cholinesterase activity revealed that the two patients were homozygous for the atypical and silent genes. respectively.

Adult↗

Differential lung ventilation during thoracotomy.

The effect of differential lung ventilation on arterial PO2 and PCO2 was compared to that achieved during one-lung ventilation in 8 patients undergoing thoracotomy. In all patients, OLV of the dependent lung, while collapsing the nondependent lung, was associated with lowering of the arterial PO2. DLV using a special double-lumen tube adaptor was then initiated; the dependent lung was preferentially ventilated by 75-80% of the tidal volume, while the nondependent lung on the operative side was only ventilated by 20-25% of the tidal volume. DLV improved oxygenation and maintained adequate carbon dioxide elimination, with minimal inflation of the nondependent lung into the surgical field. DLV may be used to increase oxygenation whenever conventional OLV is associated with hypoxemia despite the use of 100% oxygen.

Adult↗