Pretreatment with magnesium sulphate is associated with less succinylcholine-induced fasciculation and subsequent tracheal intubation-induced hemodynamic changes than precurarization with vecuronium during rapid sequence induction

Although it has side effects, succinylcholine is still widely used in rapid sequence induction. The aim of the present study is to evaluate the effects of pretreat ment with magnesium and precurarization of vecuroni um on succinylcholine-induced fasciculation and subse quent tracheal intubation-induced hemodynamic changes during rapid sequence induction. Fifty-five patients were allocated to three groups by a blinded randomization: Group M received saline 100 ml with magnesium 40 mg x kg(-1) for 5 min at 6.5 min before induction and sub sequently administered saline 1-2 ml at 1.5 min before induction; Group V received saline 100 ml for 5 min at 6.5 min before induction and subsequently administered vecuronium 0.02 mg x kg(-1) at 1.5 min before induction; Group C received saline 100 ml for 5 min at 6.5 min before induction and then saline 1-2 ml at 1.5 min before induction. Fasciculation scores and mean percent changes of heart rate, systolic blood pressure and rate pressure product between baseline and after induction were significantly lower in group M than those in group C and group V. Pretreatment with magnesium is more effective to limit succinylcholine-induced fasciculation and subsequent tracheal intubation-induced hemody namic changes in rapid sequence induction compared with vecuronium pretreatment, although magnesium does not prevent the elevation of serum potassium con centration after induction.

Sevoflurane preconditions stunned myocardium in septic but not healthy isolated rat hearts

BACKGROUND

Recent evidence indicates that sevoflurane treatment before prolonged ischaemia reduces infarct size in normal hearts, mimicking ischaemic preconditioning. We examined whether exposure to sevoflurane before brief ischaemia, inducing a 'stunned myocardium', provided such protective effects in an isolated working heart from normal or septic rats.

METHODS

With institutional approval, 91 rats were randomly allocated into one of either caecal-ligation and perforation (CLP: n=50) or sham (Sham: n=41) procedure groups 24 h before the study. After determination of baseline measurements, including cardiac output (CO), myocardial oxygen consumption (mVO(2)) and cardiac efficiency (CE; CO x peak systolic pressure/mVO(2)), each isolated heart was perfused with or without 2% sevoflurane for 15 min before global ischaemia (pre-ischaemia). After 15 min ischaemia and 30 min reperfusion, all hearts were assessed for functional recovery of myocardium (post-reperfusion).

RESULTS

During the pre-ischaemia period, 2% sevoflurane caused a significant reduction of CO in the CLP group compared with the Sham group. During the post-reperfusion period, both CO (16.9 vs 11.0 ml min(-1)) and CE (11.2 vs 7.7 mm Hg ml(-1) ( micro l O(2))(-1)) was higher in the sevoflurane-treated vs -untreated hearts from CLP rats, and was accompanied by lower incidence of reperfusion arrhythmia compared with control hearts (8 vs 32%). In contrast, 2% sevoflurane did not provide cardioprotective effects in normal rats.

CONCLUSIONS

The current study demonstrates that pre-treatment with sevoflurane minimizes myocardial dysfunction and the incidence of reperfusion arrhythmia after brief ischaemic insults in septic hearts.

[Anesthesia for thoracotomy in a patient with severe emphysema associated with Wolff-Parkinson-White syndrome]

A 57-yr-old man with Wolff-Parkinson-White syndrome was scheduled for thoracotomy due to pneumothorax caused by severe emphysema (FEV1.0% 29%). Anesthesia was induced with propofol and fentanyl and maintained with continuous propofol infusion combined with thoracic epidural anesthesia. During mechanical ventilation, the peak inspiratory pressure was reduced to avoid overinflation or rupture of the lung. Although severe hypercapnia was observed during one lung ventilation, there was no incidence of tachyarrhythmias that we had feared. We suggest that hypercapnia is unlikely to cause tachyarrhythmias in patients with WPW syndrome if carefully managed.

Epidural anesthesia retards intestinal acidosis and reduces portal vein endotoxin concentrations during progressive hypoxia in rabbits

BACKGROUND

Because it is postulated that gut is important via bacterial translocation in the development of the systemic inflammatory response and multiple organ dysfunction, the preservation of gut integrity is a therapeutic goal for physicians who care for critically ill patients. The aim of the current study was to evaluate whether epidural anesthesia prevented gut injury and subsequent translocation of endotoxin during acute progressive hypoxia in rabbits.

METHODS

After the placement of an epidural catheter, 18 male rabbits, anesthetized with buprenorphine-midazolam, were allocated randomly to two groups: 0.5% lidocaine (group E) and saline (group C) groups. The solutions (0.4 ml/kg) were injected epidurally, followed by continuous infusion (0.1 ml x kg(-1) x h(-1)) during the study period. Portal blood flow, portal endotoxin concentrations, and intramucosal pH (pHi) of the ileum were measured at baseline and during two stages of progressive hypoxia (fraction of inspired oxygen [Fio2] = 0.15 and 0.10).

RESULTS

In both study groups, the portal blood flow was preserved to a similar extent during acute hypoxia. However, pHi was reduced to a lesser extent in group E (7.33 +/- 0.12 versus 7.22 +/- 0.12 at an Fio2 of 0.15 and 7.13 +/- 0.15 versus 7.03 +/- 0.12 at an Fio2 of 0.10; mean +/- SD, P < 0.01), concurrently with lower portal endotoxin concentrations (P < 0.05) compared with group C.

CONCLUSIONS

The current study showed that epidural anesthesia slowed the progression of intestinal ischemia during acute hypoxia, subsequently preventing translocation of endotoxin through the gut mucosa.

[Changes of vascular reactivity following esophagectomy measured by near-infrared spectroscopy]

We examined the alterations of peripheral vascular responses following ischemic insult during perioperative period of esophagectomy. Increase of palm blood flow after vascular occlusion, i.e., reactive hyperemia (RH), measured by near-infrared spectroscopy (NIRS) was employed to assess forearm vascular responses. The measurements of RH were performed in esophagectomized patients (n = 12) before induction of anesthesia and postoperatively until the next day of extubation in comparison with normal volunteers (n = 11). After esophagectomy, the RH, which was comparable with those in volunteers, was depressed by 50% on 1 POD, and did not recover until the third POD. In particular, patients receiving laparoscopy-assisted surgery showed less decrease of RH than those receiving the standard open laparotomy. These results suggest that vascular responses to increase blood flow against ischemic insult is depressed following esophagectomy.

Permissive hypercapnia during thoracic anaesthesia

BACKGROUND

While permissive hypercapnia is commonly practised in critical care, it remains unclear if the comparable manoeuvres are clinically acceptable during anaesthesia. This retrospective study aimed at describing the anaesthetic implications of hypercapnia associated with deliberate hypoventilation during thoracic surgery in patients with severe emphysema.

METHODS

Thirteen patients with emphysema who required thoracic surgery under similar anaesthesia were reviewed: 3 patients were managed to maintain normocapnia (normocapnia group) whereas 10 patients developed hypercapnia (PaCO2 >70 mmHg) as a result of restricting peak airway pressures (hypercapnia group).

RESULTS

In the normocapnia group (PaCO2: 45+/-1 mmHg, mean+/-SD), no event which required therapeutic intervention during the surgery was seen, whereas 2 of 3 patients showed postoperative air leakage which persisted over 5 days. In the hypercapnia group, the maximum PaCO2 during anaesthesia ranged between 70 mmHg and 135 mmHg (98-21 mmHg). During anaesthesia, all 10 patients required inotropic support to prevent hypotension, 4 patients required tracheal gas insufflation of oxygen to the operated lung to avoid hypoxaemia and 3 patients required lidocaine to treat ventricular arrhythmia. However, the trachea was extubated in the operation theatre in 9 of 10 patients and no organ dysfunction was observed postoperatively. Four patients showed postoperative air leak on the first postoperative day, one of which persisted over 5 days.

CONCLUSION

Although there are some limitations, this preliminary study indicates that hypercapnia around 100 mmHg during anaesthesia for thoracic surgery may not be associated with serious consequences.