Leonid Minkovich

Hyperchloremia after noncardiac surgery is independently associated with increased morbidity and mortality: a propensity-matched cohort study.

BACKGROUND: The use of normal saline is associated with hyperchloremic metabolic acidosis. In this study, we sought to determine the incidence of acute postoperative hyperchloremia (serum chloride >110 mEq/L) and whether this electrolyte disturbance is associated with an increase in length of hospital stay, morbidity, or 30-day postoperative mortality. METHODS: Data were retrospectively collected on consecutive adult patients (>18 years of age) who underwent inpatient, noncardiac, nontransplant surgery between January 1, 2003 and December 31, 2008. The impact of postoperative hyperchloremia on patient morbidity and length of hospital stay was examined using propensity-matched and logistic multivariable analysis. RESULTS: The dataset consisted of 22,851 surgical patients with normal preoperative serum chloride concentration and renal function. Acute postoperative hyperchloremia (serum chloride >110 mmol/L) is quite common, with an incidence of 22%. Patients were propensity-matched based on their likelihood to develop acute postoperative hyperchloremia. Of the 4955 patients with hyperchloremia after surgery, 4266 (85%) patients were matched to patients who had normal serum chloride levels after surgery. These 2 groups were well balanced with respect to all variables collected. The hyperchloremic group was at increased risk of mortality at 30 days postoperatively (3.0% vs 1.9%; odds ratio = 1.58; 95% confidence interval, 1.25–1.98) (relative risk 1.6 or risk increase of 1.1%) and had a longer hospital stay (7.0 days [interquartile range 4.1–12.3] compared with 6.3 [interquartile range 4.0–11.3]) than patients with normal postoperative serum chloride levels. Patients with postoperative hyperchloremia were more likely to have postoperative renal dysfunction. Using all preoperative variables and measured outcome variables in a logistic regression analysis, hyperchloremia remained an independent predictor of 30-day mortality with an odds ratio of 2.05 (95% confidence interval, 1.62–2.59). CONCLUSION: This retrospective cohort trial demonstrates an association between hyperchloremia and poor postoperative outcome. Additional studies are required to demonstrate a causal relationship between these variables.

Non-invasive prospective targeting of arterial P(CO2) in subjects at rest.

Accurate measurements of arterial P  CO 2 (P  a,CO 2 ) currently require blood sampling because the end‐tidal P  CO 2 (P  ET,CO 2 ) of the expired gas often does not accurately reflect the mean alveolar P  CO 2 and P  a,CO 2. Differences between P  ET,CO 2 and P  a,CO 2 result from regional inhomogeneities in perfusion and gas exchange. We hypothesized that breathing via a sequential gas delivery circuit would reduce these inhomogeneities sufficiently to allow accurate prediction of P  a,CO 2 from P  ET,CO 2. We tested this hypothesis in five healthy middle‐aged men by comparing their P  ET,CO 2 values with P  a,CO 2 values at various combinations of P  ET,CO 2 (between 35 and 50 mmHg), P  O 2 (between 70 and 300 mmHg), and breathing frequencies (f; between 6 and 24 breaths min−1). Once each individual was in a steady state, P  a,CO 2 was collected in duplicate by consecutive blood samples to assess its repeatability. The difference between P  ET,CO 2 and average P  a,CO 2 was 0.5 ± 1.7 mmHg (P= 0.53; 95% CI −2.8, 3.8 mmHg) whereas the mean difference between the two measurements of P  a,CO 2 was −0.1 ± 1.6 mmHg (95% CI −3.7, 2.6 mmHg). Repeated measures ANOVAs revealed no significant differences between P  ET,CO 2 and P  a,CO 2 over the ranges of P  O 2, f and target P  ET,CO 2. We conclude that when breathing via a sequential gas delivery circuit, P  ET,CO 2 provides as accurate a measurement of P  a,CO 2 as the actual analysis of arterial blood.

The interaction of carbon dioxide and hypoxia in the control of cerebral blood flow.

Both hypoxia and carbon dioxide increase cerebral blood flow (CBF), and their effective interaction is currently thought to be additive. Our objective was to test this hypothesis. Eight healthy subjects breathed a series of progressively hypoxic gases at three levels of carbon dioxide. Middle cerebral artery velocity, as an index of CBF; partial pressures of carbon dioxide and oxygen and concentration of oxygen in arterial blood; and mean arterial blood pressure were monitored. The product of middle cerebral artery velocity and arterial concentration of oxygen was used as an index of cerebral oxygen delivery. Two-way repeated measures analyses of variance (rmANOVA) found a significant interaction of carbon dioxide and hypoxia factors for both CBF and cerebral oxygen delivery. Regression models using sigmoidal dependence on carbon dioxide and a rectangular hyperbolic dependence on hypoxia were fitted to the data to illustrate this interaction. We concluded that carbon dioxide and hypoxia act synergistically in their control of CBF so that the delivery of oxygen to the brain is enhanced during hypoxic hypercapnia and, although reduced during normoxic hypocapnia, can be restored to normal levels with progressive hypoxia.

Accelerated recovery from sevoflurane anesthesia with isocapnic hyperpnoea.

BACKGROUND:Isocapnic hyperpnoea (IH) reduces recovery time from isoflurane anesthesia in animals and humans. We studied the effect of IH on the emergence profile of sevoflurane-anesthetized patients by comparing postoperative recovery variables in patients administered IH (IH group) to those recovered in the customary fashion (control group). METHODS:We enrolled 30 ASA I–III patients undergoing elective gynecological surgery. Induction and maintenance of anesthesia were standardized with a protocol consisting of fentanyl, propofol, rocuronium, and sevoflurane in air/O2. Patients were randomly assigned to control (C) or IH groups at the end of the surgery. We recorded time intervals from discontinuing sevoflurane to recovery milestones. RESULTS:Time to tracheal extubation was much shorter in the IH group compared with group C (6.2 ± 2.1 vs 12.3 ± 3.8 min, respectively, P < 0.01). The IH group also had shorter times to initiation of spontaneous ventilation (4.2 ± 1.7 vs 6.5 ± 3.8 min, P = 0.047), eye opening (5.5 ± 1.4 vs 13.3 ± 4.4 min, P < 0.01), bispectral index value >75 (3.9 ± 1.1 vs 8.8 ± 3.7 min, P < 0.01), leaving operating room (7.7 ± 2.0 vs 15.3 ± 3.4 min, P < 0.01), and eligibility for postanesthetic care unit discharge (67.2 ± 19.3 vs 90.6 ± 20.0 min, P < 0.01). CONCLUSION:IH accelerates recovery from sevoflurane anesthesia and shortens operating room and postanesthetic care unit stay.

Isocapnic hyperpnoea shortens postanesthetic care unit stay after isoflurane anesthesia.

BACKGROUND: We conducted a prospective controlled clinical trial of the effect of isocapnic hyperpnoea (IH) on the times-to-recovery milestones in the operating room (OR) and postanesthetic care unit (PACU) after 1.5 to 3 hours of isoflurane anesthesia. METHODS: Thirty ASA grade I–III patients undergoing elective gynecological surgery were randomized at the end of surgery to either IH or the conventional recovery (control). Six patients with duration of anesthesia of <90 minutes were excluded from the analysis. The anesthesia protocol included propofol, fentanyl, morphine, rocuronium, and isoflurane in air/O2. Unpaired t tests and analyses of variance were used to test for differences in times-to-recovery indicators between the two groups. RESULTS: The durations of anesthesia in IH and control groups were 140.8 ± 32.7 and 142 ± 55.6 minutes, respectively (P = 0.99). The time to extubation was much shorter in the IH group than in the control group (6.6 ± 1.6 (SD) vs. 13. 6 ± 3.9 minutes, respectively; P < 0.01). The IH group also had shorter times to eye opening (5.8 ± 1.3 vs. 13.7 ± 4.5 minutes; P < 0.01), eligibility for leaving the OR (8.0 ± 1.7 vs. 17.4 ± 6.1 minutes; P < 0.01), and eligibility for PACU discharge (74.0 ± 16.5 vs. 94.5 ± 14.7 minutes; P < 0.01). There were no differences in other indicators of recovery. CONCLUSION: IH accelerates recovery after 1.5 to 3 hours of isoflurane anesthesia and shortens OR and PACU stay.

Prevalence of claustrophobia and magnetic resonance imaging after coronary artery bypass graft surgery

Background The purpose of this study was to determine the prevalence of claustrophobia in patients undergoing magnetic resonance imaging (MRI) after coronary artery bypass graft (CABG) surgery. Methods After IRB approval, we conducted a substudy of a prospective randomized controlled clinical trial of 311 patients evaluating administration of tranexamic acid and early saphenous vein graft patency with MRI after conventional CABG surgery. Chest tube drainage was measured at 6, 12, and 24 hours after surgery. The rate of transfusion and the amount of red blood cells (RBC), fresh frozen plasma (FFP), and platelets transfused were recorded. Results A total of 237(76%) patients underwent MRI after surgery. 39 (14%, [95% CI, 10.2 to 18.0]) patients experienced severe anxiety caused by a fear of enclosed space in the MRI coil necessitating termination of the procedure. Patients with claustrophobia were on average 5 years younger. They were more likely to have diabetes mellitus and hypertension. Patients with claustrophobia had increased chest tube drainage during the postoperative period. The rate of blood product transfusion was similar between the two groups but patients with claustrophobia who were transfused received significantly more RBC and FFP than patients without claustrophobia. Conclusions Postoperative claustrophobia and anxiety, leading to inability to undergo MRI, may be more common than previously described.

The Effect of Nasogastric Tube Application During Cardiac Surgery on Postoperative Nausea and Vomiting—A Randomized Trial

OBJECTIVE Postoperative nausea and vomiting (PONV) are significant morbidities following cardiac surgery. The purpose of this study was to determine if application of a nasogastric (NG) tube during cardiac surgery can reduce the prevalence of postoperative PONV. DESIGN This study was a prospective randomized controlled trial. SETTING University tertiary referral center. PARTICIPANTS Two hundred two patients undergoing elective cardiac procedures. INTERVENTIONS Patients were prospectively enrolled and randomized to either receive or not receive an NG tube after induction of anesthesia. Standard anesthetic technique and postoperative care were employed in all patients. Preoperative demographic data, pain score, nausea score and incidence of vomiting were recorded early (0-8 hours) and late (8-16 hours) following extubation. Antiemetic and analgesic medications were compared between the 2 groups. MEASUREMENTS AND MAIN RESULTS One hundred three patients were randomized to no an NG tube (controls) and 99 received an NG tube as part of their perioperative management. Demographic data and surgical characteristics were similar between the 2 groups. However, the control group had more smokers. Incidence and severity of nausea, pain scores, and analgesic requirements were similar between the 2 groups. Prevalence of vomiting was more frequent in the control group (24%) than in the NG tube group (10%, p = 0.007), and was more frequent in patients who underwent valve and redo procedures. CONCLUSIONS Use of an NG tube during cardiac surgery may reduce the incidence of postoperative vomiting.

Aortic valve thrombosis after valve-sparing aortic root replacement and insertion of an extracorporeal left ventricular assist device, masked by mediastinal packing

Aortic valve (AV) or aortic root thrombus related to a left ventricular assist device (LVAD) is a relatively uncommon but potentially life-threatening complication. In the present report, we describe a complex case where echocardiographic diagnosis of AV thrombosis was obscured by the presence of mediastinal packing in a patient who underwent valve-sparing aortic root replacement and insertion of the CentriMag™ LVAD for postcardiotomy cardiogenic shock. A large AV thrombus may develop rapidly in patients with LVADs. This case highlights the importance of a careful and thorough transesophageal echocardiography examination in detecting this complication and in altering surgical management.

Erratum to: The interaction of carbon dioxide and hypoxia in the control of cerebral blood flow

The original version of this article inadvertently contained a mistake. Due to the large number of authors participating in these experiments, Dr. Anne Battisti-Charbonney was inadvertently omitted from the list of authors but should have been included. Her affiliation at the time of these experiments was: Depart

Delirium and organic brain injury after cardiac surgery

Rita Katznelson, Toronto General Hospital, University Health Network, Toronto, ON, Canada; Susan Abbey, Toronto General Hospital, University Health Network; W Scott Beattie, Toronto General Hospital, University Health Network; L Minkovich, Toronto General Hospital, University Health Network; Z Friedman, Mount Sinai Hospital, University Health Network; H Poonawala, Toronto General Hospital, University Health Network; J Karski, Toronto General Hospital, University Health Network; G Djaiani, Toronto General Hospital, University Health Network;