Search

The minimum and maximum sound pressure levels (Lmin, Lmax) were measured, and the energy equivalent sound pressure level (Leq) and the impulse rated Leq (LAlm) were ascertained in the surgical intensive care unit and the anaesthetic and recovery room. Frequency analyses were also made of the noise from various pieces of equipment. The LAlm was never below 60 dB(A)--the wake-up threshold in man--comprising strong narrow-band impulses with Lmax more than 100 dB(A) primarily from instrument alarms. When several instruments were alerted at the same time, a broad-band noise resulted which was based on their various spectral peaks. Whilst the maximum sound level of the technical equipment was high, it was surpassed by avoidable background noise caused by the staff (e.g. falling bucket lid: 94.7 dB(A)). No relationship was found between acoustic parameters and intended type of anaesthesia or surgery. Sound level was low in dangerous situations and high during routine work.

Although many patients undergoing general anesthesia and surgery are pretreated with beta-adrenoceptor blocking drugs, hemodynamic interactions of beta-blockers and volatile anesthetics have so far only been studied in animals. We therefore designed a clinical study to evaluate the relationship between the extent of preoperative beta-adrenoceptor blockade and the hemodynamic effects of isoflurane anesthesia. Sixty-one patients with coronary artery disease (CAD) and normal global left ventricular function scheduled for elective myocardial revascularization were studied immediately prior to surgery. One group of patients (n = 39) had been treated with beta-adrenoceptor blocking agents for at least 3 weeks up to and including the day of surgery. The degree of clinical beta-adrenoceptor blockade was quantified using the isoproterenol sensitivity test. The dose of isoproterenol required to increase heart rate by 25 beats/min was defined as the chronotropic dose 25 (CD25), representing the degree of beta-adrenoceptor blockade. Hemodynamic data were collected before and during isoflurane anesthesia (0.5%-0.6% end-tidal) plus 50% nitrous oxide. Twenty-two patients without preoperative beta-blocker therapy served as a control group. Preanesthetic values of cardiac index (CI), heart rate (HR) and mean arterial pressure (MAP) were lower in patients pretreated with beta-blocking drugs, but statistically these differences were not significant when compared to data obtained in unblocked patients. Isoflurane anesthesia caused significant reductions of CI and arterial blood pressure. However, there were no significant differences in the absolute values or the percentage changes compared to baseline data obtained in awake patients between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

A case is reported of right ventricular outflow obstruction caused by hypertrophic cardiomyopathy. The pressure gradient between the inflow tract and the outflow tract of the right ventricle was 84 mm Hg. Resection of the hypertrophic muscle bundles practically eliminated the obstruction leaving only an insignificant subvalvular gradient of 2 mm Hg. Histologic examination revealed cardiac muscle cell hypertrophy and disorganization.