34th William Fitts Jr oration: the parathyroid response to acute hemorrhage, sepsis, and multiple organ failure

Forgot calcium? Admission ionized-calcium in two civilian randomized controlled trials of prehospital plasma for traumatic hemorrhagic shock

BACKGROUND

Randomized clinical trials (RCTs) support the use of prehospital plasma in traumatic hemorrhagic shock, especially in long transports. The citrate added to plasma binds with calcium, yet most prehospital trauma protocols have no guidelines for calcium replacement. We reviewed the experience of two recent prehospital plasma RCTs regarding admission ionized-calcium (i-Ca) blood levels and its impact on survival. We hypothesized that prehospital plasma is associated with hypocalcemia, which in turn is associated with lower survival.

METHODS

We studied patients enrolled in two institutions participating in prehospital plasma RCTs (control, standard of care; experimental, plasma), with i-Ca collected before calcium supplementation. Adults with traumatic hemorrhagic shock (systolic blood pressure ≤70 mm Hg or 71-90 mm Hg + heart rate ≥108 bpm) were eligible. We use generalized linear mixed models with random intercepts and Cox proportional hazards models with robust standard errors to account for clustered data by institution. Hypocalcemia was defined as i-Ca of 1.0 mmol/L or less.

RESULTS

Of 160 subjects (76% men), 48% received prehospital plasma (median age, 40 years [interquartile range, 28-53 years]) and 71% suffered blunt trauma (median Injury Severity Score [ISS], 22 [interquartile range, 17-34]). Prehospital plasma and control patients were similar regarding age, sex, ISS, blunt mechanism, and brain injury. Prehospital plasma recipients had significantly higher rates of hypocalcemia compared with controls (53% vs. 36%; adjusted relative risk, 1.48; 95% confidence interval [CI], 1.03-2.12; p = 0.03). Severe hypocalcemia was significantly associated with decreased survival (adjusted hazard ratio, 1.07; 95% CI, 1.02-1.13; p = 0.01) and massive transfusion (adjusted relative risk, 2.70; 95% CI, 1.13-6.46; p = 0.03), after adjustment for confounders (randomization group, age, ISS, and shock index).

CONCLUSION

Prehospital plasma in civilian trauma is associated with hypocalcemia, which in turn predicts lower survival and massive transfusion. These data underscore the need for explicit calcium supplementation guidelines in prehospital hemotherapy.

LEVEL OF EVIDENCE

Therapeutic, level II.

Late association of hyperparathyroidism in septic patients with multiple organ failure

BACKGROUND

Hypocalcemia after severe shock or sepsis stimulates release of parathyroid hormone (PTH), which abates with recovery. Sustained sepsis with multiple organ failure (MOF), however, may cause a resurgent release of PTH and life-threatening hypercalcemia.

METHODS

Thirty critically ill patients with prolonged sepsis developed combined hypercalcemia with elevated serum PTH levels. The primary insult was trauma in 12 patients, peritonitis in 14, and pancreatitis in 4. MOF involved the lungs in 30 patients, kidney in 16, gut in 30, brain in 13, and a coagulopathy in 10. There were 12 deaths; hospital stay averaged 81 days.

RESULTS

Hypercalcemia with increased serum levels of PTH occurred usually 3-4 weeks after the septic insult. Bradycardia, thought to be caused by the hypercalcemia, occurred in 19 patients, was attributed to a vasovagal reaction, and was treated with atropine. When asystole resulted, epinephrine and cardiopulmonary resuscitation were administered. Five patients required placement of an intravenous pacemaker. Bradycardia was acutely lethal in 4 patients; in a 5th patient, the decision was made for comfort care alone, and he died 9 days later. Bisphosphonate was given to 7 patients with this hypercalcemic-induced bradycardia and, prophylactically, to prevent bradycardia in 9 others. Hypercalcemia corrected in all patients; bradycardia abated in 7 patients.

CONCLUSION

Hyperparathyroidism may occur with MOF secondary to sepsis. The mechanism is unclear, but the resultant bradycardia can be life threatening. Treatment with bisphosphonate corrects the hypercalcemia and bradycardia. Both the hypercalcemia and the bradycardia normalize when the MOF resolves.