Influence of body temperature, with or without sedation, on energy expenditure in severe head-injured patients

OBJECTIVE

To quantify the effect of body temperature and sepsis on energy expenditure in head-injured patients.

DESIGN

Prospective, nonrandomized, observational study.

SETTING

Neurosurgical intensive care unit.

PATIENTS

Severe head-injured patients.

INTERVENTIONS

Use of an indirect calorimeter to measure energy expenditure.

MEASUREMENTS AND MAIN RESULTS

Mean arterial pressure (MAP), heart rate (HR), body temperature, and mean hourly energy expenditure were recorded. Twenty-four patients had 1,919 hourly measures of the above parameters. The measurement periods were divided into four groups, according to the anesthetic agents used for sedation: fentanyl and midazolam (group FM); fentanyl, midazolam, and curarization (group C); thiopental (group T); and no sedation (group NS). The energy expenditure/basal energy expenditure ratio (EE/BEE) was significantly lower in group T (1.20 +/- 0.15) than in group FM (1.32 +/- 0.24) or group C (1.32 +/- 0.20) and was significantly higher in group NS (1.60 +/- 0.33). There was a significant correlation between body temperature and EE/BEE (p < .0001, r2 = .27) only in sedated patients. Using the equation of the regression line to correct energy expenditure for differences in body temperatures between groups, the difference in energy expenditure between groups with sedation disappeared. This finding suggested that the low energy expenditure under thiopental was due only to hypothermia. Sepsis significantly increased energy expenditure independently of fever. There was a weak but statistically significant correlation between energy expenditure and HR (p<.01, r2 = .13) but not between energy expenditure and MAP.

CONCLUSIONS

Sedation had a major effect on energy expenditure. In sedated patients, body temperature was the main determinant of energy expenditure; the anesthetic agent used had little influence on the level of energy expenditure. Sepsis increased energy expenditure independently of fever, probably through hormonal changes.

[Transfer hypokalemia induced by norepinephrine infusion]

We report a case of a severe hypokalaemia by intracellular shift of potassium in a sedated and ventilated head trauma patient. The kalaemia which was 3.9 mmol.L-1 at admission in the intensive care unit decreased to 1.3 mmol.L-1 during a perfusion of noradrenaline (0.3 micrograms.kg-1.min-1). Following the decrease of the noradrenaline dose, and administration of potassium, the kalaemia rapidly increased to 5.3 mmol.L-1 carrying a risk of arrhythmia. Therefore, kalaemia and ECG should be closely monitored when the noradrenaline doses are reduced. The causes of transcellular shift of potassium are reviewed.

[Lack of prognostic value of the determination of 3 serum proteins during the acute phase of brain injury]

In has been suggested that monitoring of blood levels of serum proteins could be of value in order to assess the prognosis of trauma patients. A study was set up to assess the value of albuminaemia, prealbuminaemia, transferrin and ceruleoplasmin levels in intensive care unit patients admitted after multiple trauma including head injury. This study involved 43 patients (31 men and 12 women), with a mean age of 26 years (range: 15 and 71 years). Two patients had extradural haematoma. The other patients had brain contusion associated with extradural haematoma (5 cases), subdural haematoma (1 case) and open brain wound (1 case). All these patients were sedated with penthiobarbital, paralysed with pancuronium bromide and mechanically ventilated. Serum protein levels were measured on the first and eighth days of the stay in the intensive care unit. In these patients that survived, there was a significant decrease in albuminaemia and transferrin levels, no change in prealbuminaemia and a significant increase in ceruleoplasmin levels. Ten patients died during the study. They presented a greater decrease in albuminaemia and prealbuminaemia as compared with the survivors. There was no difference in the evolution of ceruleoplasmin and transferrin levels between the two groups. Thus, whilst the difference between survivors and non-survivors was significant for the group, for the individual patient the difference was too small to be of any prognostic value.

[Pulmonary edema after laryngospasm]

A case is reported of rapidly resolving pulmonary oedema following post-extubation laryngospasm in a 23 year-old healthy man who underwent emergency resection of a rectal polyp. The laryngospasm occurred immediately after extubation and resolved after administration of curare. The patient was reintubated and auscultation disclosed bilateral coarse and moist rales. Chest X-ray displayed a right pulmonary opacity. Because of the deteriorating respiratory status, mechanical ventilation was used with positive end-expiratory pressure for 18 h. Chest examination, chest X-ray and arterial blood gas levels improved steadily and the patient was discharged 24 h later. Pulmonary oedema associated with upper airway obstruction seems to be related to hypoxic pulmonary vasoconstriction and the largely subatmospheric transpulmonary pressure gradients generated while trying to breathe against a closed glottis. In addition, this increased negative intra-alveolar pressure was responsible for significant changes in cardiovascular function: right ventricular blood volume, right ventricular ejection fraction and left ventricular after-load increased, while left ventricular ejection fraction decreased. These changes favoured a rise in left atrial and pulmonary blood volumes, with transudation of fluid from the capillaries into the alveoli. Because of the severe consequences of respiratory failure, any patient who suffers acute upper airway obstruction should be observed in the recovery room for at least 3 h in order not to miss this rarely developing, but fortunately rapidly reversible, syndrome.

[Comparative effect of halothane and isoflurane on peroperative cardiac arrhythmias]

Cardiac arrhythmias were studied in twenty ASA class 1 patients under general anesthesia using halothane or isoflurane to supplement nitrous oxide in oxygen. The study began during the maintenance period, once the expiratory MAC value had reached a stable level of 1, and stopped one hour later. Both intubation and recovery periods were excluded. The end-tidal gas concentration was measured for carbon monoxide and vapours. The ECG was recorded on a magnetic tape. The incidence of arrhythmias was higher in the halothane group when compared to the isoflurane group (p less than 0.05). The main types of arrhythmias observed were supraventricular and ventricular ectopic beats. None of the arrhythmias observed were serious; in particular the ventricular beats were all unifocal and occasional. Heart rate measured at 10 min intervals tended to be more rapid in the isoflurane group.