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Biomedical subjects

V A Lazzell

Publications and source records attributed to V A Lazzell.

7 recordsLinked to original sources
PubMed2000

The effect of low concentrations of halothane on the cerebrovascular circulation in young children.

To determine the effect of halothane on cerebral blood flow velocity measured by transcranial Doppler, 23 healthy young children were studied during surgery. Anaesthesia was induced with thiopental, fentanyl and vecuronium, and maintained with halothane in 70% nitrous oxide in oxygen. A continuous epidural anaesthesia with 0. 25% bupivacaine was performed. End-tidal carbon dioxide pressure, temperature, heart rate and systolic blood pressure were kept constant. Three minimal alveolar concentrations (MAC; 0.5, 1.0 and 1. 5) of halothane were administered in stepwise increases. The cerebral blood flow velocity increased significantly at 1.0 (p < 0. 01) and 1.5 MAC (p < 0.001) compared with the value at 0.5 MAC. No further change in cerebral blood flow velocity was seen between 1.0 and 1.5 MAC. These data show that maximal changes in cerebral blood flow velocity are obtained at 1.0 MAC and that further increases in halothane concentration do not modify the cerebral circulation. It is suggested that young children differ from adults in that the maximal effect of halothane occurs at lower concentrations.

Anesthetics, Inhalation↗
PubMed1994

The incidence of masseter muscle rigidity after succinylcholine in infants and children.

To determine whether the incidence of masseter muscle rigidity is affected by the anaesthetic induction sequence, we prospectively studied for ten months the anaesthetic course in 5,641 infants and children who received muscle relaxation to facilitate tracheal intubation. The anaesthetic induction sequence consisted of intravenous sodium thiopentone (STP) 5 mg.kg-1 alone, halothane induction alone 1-4%, or halothane followed by STP. Inhalational inductions with halothane included nitrous oxide and oxygen. Tracheal intubation was facilitated by either intravenous succinylcholine (Sch) at least 1.5 mg.kg-1 or by a non-depolarizing muscle relaxant. The induction sequence and all episodes of MMR were recorded. Ninety percent of the patients received Sch and 10% received a non-depolarising agent. Of those who received Sch, 88% (5,064 patients) were anaesthetised with STP and 12% (607 patients) were anaesthetised with halothane alone or halothane followed by STP. Masseter muscle rigidity was defined clinically by the transient inability to distract the mandible from the maxilla such that the mouth could not be opened or could only be opened with force. No children anaesthetised with STP followed by Sch developed MMR. One child (0.9%) developed MMR after halothane and Sch and two developed MMR after halothane, STP and Sch (0.4%). The incidence of MMR after Sch was less with STP than with halothane alone or with halothane and STP (P < 0.025). The peak CPK values in the three children who developed MMR were 17,580 IU.L-1 after halothane and Sch, and 7,280 IU.-1 and 3,273 IU.-1 after halothane, STP and Sch. There was no evidence of MH reactions in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1991

Stability of the intraoperative arterial to end-tidal carbon dioxide partial pressure difference in children with congenital heart disease.

The purpose of this study was to evaluate the stability of the arterial PCO2 (PaCO2) to end-tidal PCO2 (PETCO2) partial pressure difference (Pa-ETCO2) during surgery using PETCO2 monitoring, in children with congenital heart disease (CHD). Forty children with CHD were studied: ten children with no interchamber communication and normal pulmonary blood flow (PBF) (normal group); ten acyanotic children with increased PBF (acyanotic-shunting group); ten cyanotic children with mixing type lesions and normal or increased PBF (mixing group), and ten cyanotic children with right-to-left intracardiac shunts demonstrating decreased and variable PBF (cyanotic-shunting group). Simultaneous PaCO2 recordings and PETCO2 measurements were obtained for each patient during five intraoperative events: (1) control time, arterial line placement under anaesthesia; (2) time 1, patient preparation; (3) time 2, immediately after sternotomy; (4) time 3, after heparin administration; and (5) time 4, immediately after aortic cannulation. Initially, cyanotic children demonstrated a greater Pa-ETCO2 compared with acyanotic children (P less than 0.05). There was no difference in the Pa-ETCO2 over time in the control, acyanotic-shunting, or mixing groups. The Pa-ETCO2 in the children with cyanotic-shunting lesions at times 2 and 3 was greater (P less than 0.05) than at their control times. We conclude that the Pa-ETCO2 of children with acyanotic-shunting and mixing congenital heart lesions is stable intraoperatively, although patients with mixing congenital heart lesions may demonstrate large individual variations. In children with cyanotic-shunting congenital heart lesions, the Pa-ETCO2 is not stable. The PETCO2 cannot be used during surgery to estimate reliably the PaCO2 in children with cyanotic CHD.

Adolescent↗
PubMed1988

Beneficial effect of norepinephrine in the treatment of circulatory shock caused by tricyclic antidepressant overdose.

The beneficial effect of dopamine in circulatory shock induced by tricyclic antidepressants (TCA) overdose may be decreased due to compromise of the endogenous stores of norepinephrine caused by TCA. The successful outcome of two cases of TCA overdose complicated by hypotension, unresponsive to an initial treatment with physostigmine fluid challenge and dopamine (greater than 15 micrograms/kg/min) but subsequently responsive to an infusion of norepinephrine is reported.

Antidepressive Agents, Tricyclic↗
PubMed1988

Cardiac arrest after acute hyperphosphatemia.

Symptoms of hyperphosphatemia usually relate to the associated hypocalcemia. In a 33-year-old patient accidental infusion of a bolus of potassium phosphate (5 ml intravenously) was immediately followed by cardiac arrest. During CPR, clinically important hypocalcemia or hyperkalemia was not detected, but serum phosphorus was significantly increased. Because acute phosphate load can precipitate life-threatening cardiac arrhythmias, familiarity with doses and rate of infusion of phosphate is extremely important.

Acute Disease↗
PubMed1983

Depressed macrophage functions at temperatures below 37 degrees C.

Immunobiological properties of guinea pig and human peritoneal macrophages were studied at temperatures ranging from 25 degrees C to 37 degrees C. Glass adherence, random migration, response to MIF and killing of Salmonella typhimurium and Saccharomyces cerevesiae by guinea pig macrophages were decreased with temperatures below 37 degrees C. Killing of Sacch. cerevesiae by human macrophages was also reduced at temperatures less than 37 degrees C. Acid phosphatase and beta-N-acetylglucosaminidase (NAG) activity assayed at 37 degrees C did not change when the cells were preincubated for 1 and 5 hours at various temperatures. Impaired macrophage function with subnormal temperatures may contribute to enhanced susceptibility to infection of patients with chronic diseases such as renal failure and cirrhosis.

Acetylglucosaminidase↗