PubMed · 15264750
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M Westphal, C Ertmer, H Van Aken, H G Bone. 2004. Pressure or flow?. https://pubmed.ncbi.nlm.nih.gov/15264750/
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OBJECTIVE: Imbalances of pulmonary to systemic blood flow ratio (Q(p)/Q(s)) compounded with inadequate systemic oxygen delivery correlate with mortality after first-stage Norwood palliation of hypoplastic left heart syndrome. Mathematical models suggest that maximal systemic oxygen delivery occurs with Q(p)/Q(s) of less than 1. Whether this applies to clinical practice is unclear. This study evaluates the level of Q(p)/Q(s) that correlates with best hemodynamic status in the first 48 postoperative hours. METHODS: Hemodynamic data of 25 consecutive patients who underwent Norwood procedure from October 2002 to January 2005 were retrospectively analyzed. Data included, in particular, systemic venous and arterial oxygen saturation (SvO(2) and SaO(2), respectively), Q(p)/Q(s), lactate levels, and doses of required inotropes. Parameters were recorded 3 hourly. Data were assigned to three groups according to their corresponding Q(p)/Q(s): Groups 1, 2, and 3 for Q(p)/Q(s)< or =1, Q(p)/Q(s) between 1 and 2, and Q(p)/Q(s)> or =2, respectively. Thereafter, independent t-test or Fisher's exact test was used to reveal significant differences. Q(p)/Q(s) ratios and lactate levels were compared in hospital survivors and non-survivors. RESULTS: Out of 343 samples, 110, 184, and 49 were assigned to groups 1, 2, and 3, respectively. Group 1 (Q(p)/Q(s)< or =1) was characterized by lower SaO(2) (p<0.001) with similar SvO(2) (p=0.3 and p=0.5) and, therefore, higher systemic oxygen delivery (arteriovenous oxygen saturation difference, p<0.001; oxygen excess factor, p<0.001) compared to groups 2 and 3. However, lower mean arterial pressure (p=0.07 and p<0.001), higher lactate levels (p=0.009 and p=0.01), and norepinephrine doses (p=0.006 and p<0.001) highlighted worse hemodynamics. The best hemodynamic status corresponded to group 2. Q(p)/Q(s) remained above 1 in 21 survivors and was, most of the times, below 1 in four patients who died. Lactate levels were almost always above 4 mmol/l or increasing in non-survivors. CONCLUSIONS: Maximum oxygen delivery after Norwood operation occurs at Q(p)/Q(s) of less than 1. However, optimal hemodynamic status and end-organ function and higher survival correlates with Q(p)/Q(s) between 1 and 2. Thus, Q(p)/Q(s) should be targeted at 1.5 for improved course early after first-stage Norwood palliation.
Renal ultrasound is a valuable tool to measure allograft diameters and hemodynamic changes, some of which may help us to predict ongoing rejection. Longitudinal (L) and horizontal (H) diameters, and resistive index (RI) of intrarenal arteries of kidneys were measured before transplantation in the donor site, as well as 1 week after transplantation in the recipient site (7.5 MHz probe). We excluded patients with acute rejection, delayed graft function, perinephric collection, suspected allograft artery stenosis, or serum creatinine >2 mg/dL. Finally, allograft measurements were compared with the donor parameters. The mean values of L and H diameters in 32 normal allografts were: L 119 +/- 10.4 mm; H 54 +/- 8.4 mm; L/H ratio 2.25 +/- 0.27; RI 0.57 +/- 0.55. The mean values of these measurements when the kidney was in the donor body were: L 110 +/- 9.4 mm; H 44.3 +/- 5.4 mm; L/H ratio 2.97 +/- 0.25; RI 0.61 +/- 0.040. Both L and H diameters were increased significantly after transplantation, but the L/H ratio and RI were decreased significantly (P < .05). The presumed physiologic explanations for these findings in allograft are increased blood flow, decreased intrarenal arterial resistance, stress relaxation, and lack of sympathetic innervation.
PURPOSE OF REVIEW: During anesthesia and surgery oxygen is routinely administered to all patients. Inspired oxygen concentrations, however, vary between 30 and 100%, and oxygen is often administered in a seemingly random manner. During the last decade it has been shown in several randomized trials that perioperative supplemental oxygen administration might improve outcome after certain surgical procedures. The purpose of this review is to provide an overview about the benefits and risks of supplemental oxygen administration in the perioperative period. RECENT FINDINGS: Supplemental oxygen improves immune function. Furthermore, 80% inspired oxygen fraction almost doubles subcutaneous tissue oxygen tension and halves the rate of postoperative wound infections. Some studies have shown that supplemental oxygen also decreases the rate of postoperative nausea and vomiting after laparoscopic and open abdominal surgical procedures. Preconditioning with oxygen might improve organ function after liver transplantation and outcome after spinal ischemic insults. Supplemental perioperative oxygen administration is not associated with clinically important side effects. SUMMARY: Supplemental oxygen administration during the perioperative period might be a simple, inexpensive and well-tolerated treatment option to improve patient outcome. The optimal inspired oxygen concentration still needs to be evaluated.