An evaluation of fresh gas flow rates for spontaneously breathing cats and small dogs on the Humphrey ADE semi-closed breathing system.

OBJECTIVE: To evaluate the fresh gas flow (FGF) rate requirements for the Humphrey ADE semi-closed breathing system in the Mapleson A mode; to determine the FGF at which rebreathing occurs, and compare the efficiency of this system to the Bain (Mapleson D) system in spontaneously breathing cats and small dogs. STUDY DESIGN: Prospective clinical study. ANIMALS: Twenty-five healthy (ASA score I or II) client-owned cats and dogs (mean ± SD age 4.7 ± 5.0 years, and body weight 5.64 ± 3.26 kg) undergoing elective surgery or minor procedures. METHODS: Anaesthesia was maintained with isoflurane delivered via the Humphrey ADE system in the A mode using an oxygen FGF of 100 mL kg(-1) minute(-1). The FGF was then reduced incrementally by 5-10 mL kg(-1) minute(-1) at approximately five-minute intervals, until rebreathing (inspired CO(2) >5 mmHg (0.7 kPa)) was observed, after which flow rates were increased. In six animals, once the minimum FGF at which rebreathing occurred was found, the breathing system was changed to the Bain, and the effects of this FGF delivery examined, before FGF was increased. RESULTS: Rebreathing did not occur at the FGF recommended by the manufacturer for the ADE. The mean ± SD FGF that resulted in rebreathing was 60 ± 20 mL kg(-1) minute(-1). The mean minimum FGF at which rebreathing did not occur with the ADE was 87 ± 39 mL kg(-1) minute(-1). This FGF resulted in significant rebreathing (inspired CO(2) 8.8 ± 2.6 mmHg (1.2 ± 0.3 kPa)) on the Bain system. CONCLUSIONS: The FGF rates recommended for the Humphrey ADE are adequate to prevent rebreathing in spontaneously breathing cats and dogs <15 kg. CLINICAL RELEVANCE: The Humphrey ADE system used in the A mode is a more efficient alternative to the Bain system, for maintenance of gaseous anaesthesia in spontaneously breathing cats and small dogs.

Nonresponse to clozapine and premorbid functioning in treatment of refractory schizophrenia.

INTRODUCTION: It is recognized that early treatment can improve outcomes and generally improve recovery potential for those with schizophrenia. Data suggest that poor premorbid functioning has been found to be related to more severe symptoms and poor antipsychotic response; however, little is known about premorbid functioning in patients who have no response to clozapine treatment. METHODS: This study compares the premorbid functioning among patients who responded to clozapine treatment (20% decrease in total Brief Psychiatric Rating Scale [BPRS] score; n = 35) and those who did not respond (n = 50) to 8 weeks of clozapine treatment. Premorbid functioning was assessed using the Cannon-Spoor Premorbid Adjustment Scale. RESULTS: Patients who did not respond to clozapine had significantly lower total BPRS scores (P = .01) at baseline, driven primarily by lower ratings in hostility (P = .007) and activation (P = .02), compared with those who responded to clozapine. Responders and nonresponders did not differ in their age, race, level of education, marital status, age of onset, characterization of the deficit syndrome, and positive or negative symptoms. Nonresponders to clozapine did not improve in any area of symptoms or global functioning, whereas there were significant improvements in BPRS total scores (analysis of covariance) and all symptom domains in the responder groups (P < .0001). Level of functioning scores in those who responded to clozapine was significantly higher at end point (P = .02). As for premorbid functioning, there were no differences in scores between responders and nonresponders at the time of early and late adolescence; however, there was a trend toward lower premorbid functioning in the clozapine nonresponders on most childhood measures (before the age of 11 years). Clozapine nonresponders tended to be less social and more withdrawn as compared with those who responded to clozapine (P = .08), as well as tended to have poorer adaptation to school (P = .06) and fewer peer relationships (P = .08). These results did not reach significance. Work and/or school performance changed more insidiously in the nonresponders group before illness onset (P = .045). DISCUSSION: Clozapine is beneficial to many patients with treatment-resistant symptoms; however, nonresponse to this medication may represent a subtype of patients who may present differently with symptoms. These findings should encourage further examination of early childhood indicators and opportunities for appropriate and effective intervention.

Risperidone, quetiapine, and fluphenazine in the treatment of patients with therapy-refractory schizophrenia.

This 12-week, double-blind study evaluated the effectiveness of risperidone (4 mg/day), quetiapine (400 mg/day), or fluphenazine (12.5 mg/day) in a stringently defined treatment-resistant population of people with schizophrenia. No differences were noted in total Brief Psychiatric Rating Scale (BPRS) or Clinical Global Impression scores among the drug groups (n = 38). More subjects tended to complete the study on risperidone (69%) or quetiapine (58%) than those treated with fluphenazine (31%; P value not significant). Eighty-nine percent of those who discontinued on fluphenazine (8 of 9) were due to lack of efficacy. Discontinuation due to adverse effects was low, with only 2 subjects (both on quetiapine) stopping due to side effects. Three of 13 risperidone-treated subjects (23%) and 3 of 12 quetiapine-treated subjects (25%) met response criteria (decrease of 20% of total BPRS score), whereas 2 of 13 subjects (15%) responded to fluphenazine. Side effect occurrence was similar among drug groups and EPS ratings on the Simpson Angus Scale improved in all drug groups (quetiapine, 1.64; risperidone, 1.30; fluphenazine, 0.69; P value not significant). Despite the newer class of second-generation antipsychotic medications, this treatment-resistant population remains difficult to treat. Many people have only minimal to modest improvements with antipsychotic treatment and most continue to have residual psychotic symptoms. Treatment with first- and second-generation antipsychotics may demonstrate similar efficacy; however, patients treated with second-generation antipsychotics may be more likely to adhere to treatment.

Clozapine treatment in patients with prior substance abuse.

OBJECTIVE: This study examined outcomes following discharge on clozapine for treatment-resistant schizophrenia patients with and without diagnosed substance abuse histories. METHODS: Those discharged on clozapine from a research unit between April 1991 and March 1996 were followed with respect to hospitalization status. Of the treatment-resistant patients with schizophrenia, 19 were diagnosed as individuals with substance abuse, while 26 patients had no history of abuse. Patients were openly treated with clozapine and were included in the study if they were stabilized and discharged on the medication. RESULTS: Patients who had histories of abuse exhibited a better treatment response and a lower total Brief Psychiatric Rating Scale (BPRS) score at discharge, compared with the non-substance abuse group. One-year readmission rates were 21% and 23% in patients with and without prior substance abuse histories, respectively (P = ns). CONCLUSIONS: Clozapine may be a therapeutic option for the dually diagnosed population and may offer benefits to patients with schizophrenia who have a history of substance abuse.