Equality of the in vivo and in vitro oxygen-binding capacity of haemoglobin in patients with severe respiratory disease.

The in vivo and in vitro oxygen-binding capacity of haemoglobin was determined on 10 occasions in nine patients who required mechanical ventilation. The in vitro sample was tonometered with 97% oxygen for 10 min and then with air, while the in vivo sample was obtained after 20 min of lung ventilation with pure oxygen. Subsequent laboratory procedures were identical for both samples. The mean oxygen-binding capacity of haemoglobin in vitro and in vivo samples were almost equal (1.365 +2- 0.010 and 1,366 +/- 0.007 ml per g Hb). When the measured inactive fractions of haemoglobin (carboxy- and methaemoglobin) were taken into account, these values increased to 1.392 +/- 0.005 and 1.392 +/- 0.007 ml per g Hb respectively.

Abnormal temperature control after intoxication with short-acting barbiturates.

Changes in rectal and toe temperatures were measured in 16 patients who had been intoxicated with short-acting barbiturates. The lowest temperatures observed in the group of 16 patients averaged 35.5 +/- 2.0 degrees C. In 11 patients, the interval between intoxication and admission was documented. There was a significant correlation (r = 0.83) between the time of estimated intoxication and hypothermia. Patients who were admitted soon after the ingestion of the barbiturates had the lowest rectal temperatures. These observations indicate that hypothermia is a usual clinical sign in the initial period after intoxication with a short-acting barbiturate. Except for 2 patients, rectal temperature exceeded 38 degrees C during the interval of recovery with the maximum rectal temperature averaging 39.0 +/- 0.8 degrees C. Hyperthermia was not related to infection of the airways, lungs, urinary tract, or bloodstream. In 11 patients, pathogenic organisms were recovered from the airway and/or urine, but there was no difference in the highest rectal temperature in these patients (39.0 +/- 0.9 degrees C) when compared with 5 patients from whom no pathogenic organisms were recovered (39.2 +/- 0.7 degrees C). Accordingly, there was no evidence that hyperthermia was due to infection. The skin temperatures of the ventrum of the first toe were not typically decreased during hypothermia. To the contrary, increases in skin temperatures were often observed during hypothermia. These observations provide evidence of altered thermoregulation with increased surface heat loss accounting for the hypothermia in the early course and heat conservation with hyperthermia during the later course of intoxication by short-acting barbiturates.

Amikacin treatment of Serratia septicemia in critically ill patients.

Serratia marcescens septicemia represents a serious problem in high risk critical care patients. Treatment is difficult because Serratia is usually resistant to most antibiotics. Amikacin is at present the most effective antibiotic in vitro against gentamycin-resistant Serratia, although significant loss of activity may occur in vivo in the group of compromised patients, whose ultimate prognosis may depend eventually upon other associated conditions. In this Medical ICU, 15 patients with Serratia septicemia who were treated with in vitro effective antibiotics (14 were given amikacin) had a mortality of 60%, while 5 patients who received ineffective in vitro antibiotics had a mortality of 100%. In this ICU, 80% of the Serratia isolates were resistant to gentamycin, while only 2.8% were resistant to amikacin. Because amikacin-resistant strains of Serratia have already emerged, appropriate use of this antibiotic is essential in order not to promote the selection of amikacin-resistant strains.

Effects of positive end-expiratory pressure on renal function.

The effects were studied positive end-expiratory pressure (PEEP) on renal function in eight patients with acute respiratory failure, requiring mechanical ventilation. On application of PEEP + 10 cm H2O, central venous pressure increased, systolic blood pressure decreased, urine flow and PAH-clearance were reduced, while inulin clearance remained stable. There was a marked increase in fractional sodium reabsorption and a concurrent decrease in fractional osmolal excretion. Fractional free-water clearance and the ratio UOsm/POsm did change.

Early postsurgical bacterial contamination of the airways: a study on 28 open-heart patients.

One pre- and two postoperative cultures of tracheo-bronchial secretions were obtained from 28 cardiac patients, subjected to open-heart surgery. Four patients received preoperative antibiotics, and all but one received postoperative prophylactic antibiotics. Preoperatively, only one patient had potential pathogens; after surgery (mean intubation time 4.2 h), four patients (14.3%) had organisms; and after 19 h of intubation, 28% of the patients had potential pathogens in their tracheo-bronchial secretions. Only three of the seven organisms recovered from the last sample were clearly sensitive to the antibiotics given prophylactically; and two of these organisms were Group A beta-haemolytic streptococci. The early presence of organisms in the airways after intubation, the high incidence of colonization, and the ineffectiveness of prophylactic antibiotics in preventing this contamination are pointed out. The factors that may possibly influence colonization of airways among these patients are commented on.